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Sample records for hydrocarbons repairing cell

  1. Direct hydrocarbon fuel cells

    Science.gov (United States)

    Barnett, Scott A.; Lai, Tammy; Liu, Jiang

    2010-05-04

    The direct electrochemical oxidation of hydrocarbons in solid oxide fuel cells, to generate greater power densities at lower temperatures without carbon deposition. The performance obtained is comparable to that of fuel cells used for hydrogen, and is achieved by using novel anode composites at low operating temperatures. Such solid oxide fuel cells, regardless of fuel source or operation, can be configured advantageously using the structural geometries of this invention.

  2. LIQUID HYDROCARBON FUEL CELL DEVELOPMENT.

    Science.gov (United States)

    A compound anode consists of a reforming catalyst bed in direct contact with a palladium-silver fuel cell anode. The objective of this study was to...prove the feasibility of operating a compound anode fuel cell on a liquid hydrocarbon and to define the important parameters that influence cell...performance. Both reformer and fuel cell tests were conducted with various liquid hydrocarbon fuels. Included in this report is a description of the

  3. Bone repair and stem cells.

    Science.gov (United States)

    Ono, Noriaki; Kronenberg, Henry M

    2016-10-01

    Bones are an important component of vertebrates; they grow explosively in early life and maintain their strength throughout life. Bones also possess amazing capabilities to repair-the bone is like new without a scar after complete repair. In recent years, a substantial progress has been made in our understanding on mammalian bone stem cells. Mouse genetic models are powerful tools to understand the cell lineage, giving us better insights into stem cells that regulate bone growth, maintenance and repair. Recent findings about these stem cells raise new questions that require further investigations.

  4. Occupational exposure to fluorinated hydrocarbons during refrigeration repair work.

    Science.gov (United States)

    Gjølstad, Merete; Ellingsen, Dag G; Espeland, Oscar; Nordby, Karl-Christian; Evenseth, Harald; Thorud, Syvert; Skaugset, Nils Petter; Thomassen, Yngvar

    2003-04-01

    This study describes refrigeration repair workers' occupational exposures to halogenated refrigerants, focusing on difluorochloromethane (HCFC 22), tetrafluoroethane (HFC 134a) and a mixture of tri-, tetra- and pentafluoroethane (R404A) in 30 work operations. Unlike earlier reported studies, the present study includes working procedures involving welding in order to measure possible occupational exposure to decomposition products. The measurements included hydrogen fluoride (HF), hydrogen chloride (HCl), phosgene (COCl2) and volatile organic compounds (VOC). The exposures were assessed during work operations on small-scale cooling installations like refrigerators and freezers. The repair workers' occupational exposures to refrigerants were moderate, and the major part of the exposures were associated with specific working procedures lasting for relatively short periods of time (welding operations lasted only for short periods of time, HF was detected in 9 out of 15 samples when HCFC 22, HFC 134a or R404A had been used. Hydrogen chloride was detected in 3 out of 5 samples in air polluted with HCFC 22. Phosgene was not detected. A large number of VOCs in various concentrations were found during welding. Except for the applied refrigerants, halogenated compounds were only found in one sample.

  5. Cell healing: calcium, repair and regeneration

    Science.gov (United States)

    Moe, Alison; Golding, Adriana E.; Bement, William M.

    2016-01-01

    Cell repair is attracting increasing attention due to its conservation, its importance to health, and its utility as a model for cell signaling and cell polarization. However, some of the most fundamental questions concerning cell repair have yet to be answered. Here we consider three such questions: 1) How are wound holes stopped? 2) How is cell regeneration achieved after wounding? 3) How is calcium inrush linked to wound stoppage and cell regeneration? PMID:26514621

  6. Nucleotide excision repair in differentiated cells

    Energy Technology Data Exchange (ETDEWEB)

    Wees, Caroline van der [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Department of Cardiology, Leiden University Medical Center, Leiden (Netherlands); Jansen, Jacob [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Vrieling, Harry [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Laarse, Arnoud van der [Department of Cardiology, Leiden University Medical Center, Leiden (Netherlands); Zeeland, Albert van [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands); Mullenders, Leon [Department of Toxicogenetics, Leiden University Medical Center, Leiden (Netherlands)]. E-mail: l.mullenders@lumc.nl

    2007-01-03

    Nucleotide excision repair (NER) is the principal pathway for the removal of a wide range of DNA helix-distorting lesions and operates via two NER subpathways, i.e. global genome repair (GGR) and transcription-coupled repair (TCR). Although detailed information is available on expression and efficiency of NER in established mammalian cell lines, little is known about the expression of NER pathways in (terminally) differentiated cells. The majority of studies in differentiated cells have focused on repair of UV-induced cyclobutane pyrimidine dimers (CPD) and 6-4-photoproducts (6-4PP) because of the high frequency of photolesions at low level of toxicity and availability of sensitive technologies to determine photolesions in defined regions of the genome. The picture that emerges from these studies is blurred and rather complex. Fibroblasts and terminally differentiated myocytes of the rat heart display equally efficient GGR of 6-4PP but poor repair of CPD due to the absence of p48 expression. This repair phenotype is clearly different from human terminal differentiated neurons. Furthermore, both cell types were found to carry out TCR of CPD, thus mimicking the repair phenotype of established rodent cell lines. In contrast, in intact rat spermatogenic cells repair was very inefficient at the genome overall level and in transcriptionally active genes indicating that GGR and TCR are non-functional. Also, non-differentiated mouse embryonic stem (ES) cells exhibit low levels of NER after UV irradiation. However, the mechanisms that lead to low NER activity are clearly different: in differentiated spermatogenic cells differences in chromatin compaction and sequestering of NER proteins may underlie the lack of NER activity in pre-meiotic cells, whereas in non-differentiated ES cells NER is impaired by a strong apoptotic response.

  7. Schwann cells for spinal cord repair

    Directory of Open Access Journals (Sweden)

    Oudega M.

    2005-01-01

    Full Text Available The complex nature of spinal cord injury appears to demand a multifactorial repair strategy. One of the components that will likely be included is an implant that will fill the area of lost nervous tissue and provide a growth substrate for injured axons. Here we will discuss the role of Schwann cells (SCs in cell-based, surgical repair strategies of the injured adult spinal cord. We will review key studies that showed that intraspinal SC grafts limit injury-induced tissue loss and promote axonal regeneration and myelination, and that this response can be improved by adding neurotrophic factors or anti-inflammatory agents. These results will be compared with several other approaches to the repair of the spinal cord. A general concern with repair strategies is the limited functional recovery, which is in large part due to the failure of axons to grow across the scar tissue at the distal graft-spinal cord interface. Consequently, new synaptic connections with spinal neurons involved in motor function are not formed. We will highlight repair approaches that did result in growth across the scar and discuss the necessity for more studies involving larger, clinically relevant types of injuries, addressing this specific issue. Finally, this review will reflect on the prospect of SCs for repair strategies in the clinic.

  8. [DNA homologous recombination repair in mammalian cells].

    Science.gov (United States)

    Popławski, Tomasz; Błasiak, Janusz

    2006-01-01

    DNA double-strand breaks (DSBs) are the most serious DNA damage. Due to a great variety of factors causing DSBs, the efficacy of their repair is crucial for the cell's functioning and prevents DNA fragmentation, chromosomal translocation and deletion. In mammalian cells DSBs can be repaired by non-homologous end joining (NHEJ), homologous recombination (HRR) and single strand annealing (SSA). HRR can be divided into the first and second phase. The first phase is initiated by sensor proteins belonging to the MRN complex, that activate the ATM protein which target HRR proteins to obtain the second response phase--repair. HRR is precise because it utilizes a non-damaged homologous DNA fragment as a template. The key players of HRR in mammalian cells are MRN, RPA, Rad51 and its paralogs, Rad52 and Rad54.

  9. DNA repair responses in human skin cells

    Energy Technology Data Exchange (ETDEWEB)

    Hanawalt, P.C.; Liu, S.C.; Parsons, C.S.

    1981-07-01

    Sunlight and some environmental chemical agents produce lesions in the DNA of human skin cells that if unrepaired may interfere with normal functioning of these cells. The most serious outcome of such interactions may be malignancy. It is therefore important to develop an understanding of mechanisms by which the lesions may be repaired or tolerated without deleterious consequences. Our models for the molecular processing of damaged DNA have been derived largely from the study of bacterial systems. Some similarities but significant differences are revealed when human cell responses are tested against these models. It is also of importance to learn DNA repair responses of epidermal keratinocytes for comparison with the more extensive studies that have been carried out with dermal fibroblasts. Our experimental results thus far indicate similarities for the excision-repair of ultraviolet-induced pyrimidine dimers in human keratinocytes and fibroblasts. Both the monoadducts and the interstrand crosslinks produced in DNA by photoactivated 8-methoxypsoralen (PUVA) can be repaired in normal human fibroblasts but not in those from xeroderma pigmentosum patients. The monoadducts, like pyrimidine dimers, are probably the more mutagenic/carcinogenic lesions while the crosslinks are less easily repaired and probably result in more effective blocking of DNA function. It is suggested that a split-dose protocol that maximizes the production of crosslinks while minimizing the yield of monoadducts may be more effective and potentially less carcinogenic than the single ultraviolet exposure regimen in PUVA therapy for psoriasis.

  10. Titanium dioxide nanoparticles provide protection against polycyclic aromatic hydrocarbon BaP and chrysene-induced perturbation of DNA repair machinery: A computational biology approach.

    Science.gov (United States)

    Dhasmana, Anupam; Jamal, Qazi Mohd Sajid; Gupta, Richa; Siddiqui, Mohd Haris; Kesari, Kavindra Kumar; Wadhwa, Gulshan; Khan, Saif; Haque, Shafiul; Lohani, Mohtashim

    2016-07-01

    We examined the interaction of polycyclic hydrocarbons (PAHs) like benzo-α-pyrene (BaP), chrysene, and their metabolites 7,8-dihydro-7,8-dihydroxybenzo(a)pyrene,9,10-oxide (BPDE) and chrysene 1,2-diol-3,4-epoxide-2 (CDE), with the enzymes involved in DNA repair. We investigated interaction of 120 enzymes with PAHs and screened out 40 probable targets among DNA repair enzymes, on the basis of higher binding energy than positive control. Out of which, 20 enzymes lose their function in the presence of BaP, chrysene, and their metabolites, which may fetter DNA repair pathways resulting in damage accumulation and finally leading to cancer formation. We propose the use of nanoparticles as a guardian against the PAH's induced toxicity. PAHs enter the cell via aryl hydrocarbon receptor (AHR). TiO2 NP showed a much higher docking score with AHR (12,074) as compared with BaP and chrysene with AHR (4,600 and 4,186, respectively), indicating a preferential binding of TiO2 NP with the AHR. Further, docking of BaP and chrysene with the TiO2 NP bound AHR complex revealed their strong adsorption on TiO2 NP itself, and not on their original binding site (at AHR). TiO2 NPs thereby prevent the entry of PAHs into the cell via AHR and hence protect cells against the deleterious effects induced by PAHs.

  11. Mononuclear Cells and Vascular Repair in HHT

    Directory of Open Access Journals (Sweden)

    Calinda eDingenouts

    2015-03-01

    Full Text Available Hereditary hemorrhagic telangiectasia (HHT or Rendu-Osler-Weber disease is a rare genetic vascular disorder known for its endothelial dysplasia causing arteriovenous malformations and severe bleedings. HHT-1 and HHT-2 are the most prevalent variants and are caused by heterozygous mutations in endoglin and ALK1, respectively. An undervalued aspect of the disease is that HHT patients experience persistent inflammation. Although endothelial and mural cells have been the main research focus trying to unravel the mechanism behind the disease, wound healing is a process with a delicate balance between inflammatory and vascular cells. Inflammatory cells are part of the mononuclear cells (MNCs fraction, and can, next to eliciting an immune response, also have angiogenic potential. This biphasic effect of MNC can hold a promising mechanism to further elucidate treatment strategies for HHT patients. Before MNC are able to contribute to repair, they need to home to and retain in ischemic and damaged tissue. Directed migration (homing of mononuclear cells following tissue damage is regulated by the stromal cell derived factor 1 (SDF1. MNCs that express the C-X-C chemokine receptor 4 (CXCR4 migrate towards the tightly regulated gradient of SDF1. This directed migration of monocytes and lymphocytes can be inhibited by dipeptidyl peptidase 4 (DPP4. Interestingly, MNC of HHT patients express elevated levels of DPP4 and show impaired homing towards damaged tissue. Impaired homing capacity of the MNCs might therefore contribute to the impaired angiogenesis and tissue repair observed in HHT patients. This review summarizes recent studies regarding the role of MNCs in the etiology of HHT and vascular repair, and evaluates the efficacy of DPP4 inhibition in tissue integrity and repair.

  12. Stem cells and repair of lung injuries

    Directory of Open Access Journals (Sweden)

    Randell Scott H

    2004-07-01

    Full Text Available Abstract Fueled by the promise of regenerative medicine, currently there is unprecedented interest in stem cells. Furthermore, there have been revolutionary, but somewhat controversial, advances in our understanding of stem cell biology. Stem cells likely play key roles in the repair of diverse lung injuries. However, due to very low rates of cellular proliferation in vivo in the normal steady state, cellular and architectural complexity of the respiratory tract, and the lack of an intensive research effort, lung stem cells remain poorly understood compared to those in other major organ systems. In the present review, we concisely explore the conceptual framework of stem cell biology and recent advances pertinent to the lungs. We illustrate lung diseases in which manipulation of stem cells may be physiologically significant and highlight the challenges facing stem cell-related therapy in the lung.

  13. Brain repair: cell therapy in stroke

    Directory of Open Access Journals (Sweden)

    Kalladka D

    2014-02-01

    Full Text Available Dheeraj Kalladka, Keith W Muir Institute of Neuroscience and Psychology, University of Glasgow, Southern General Hospital, Glasgow, United Kingdom Abstract: Stroke affects one in every six people worldwide, and is the leading cause of adult disability. Some spontaneous recovery is usual but of limited extent, and the mechanisms of late recovery are not completely understood. Endogenous neurogenesis in humans is thought to contribute to repair, but its extent is unknown. Exogenous cell therapy is promising as a means of augmenting brain repair, with evidence in animal stroke models of cell migration, survival, and differentiation, enhanced endogenous angiogenesis and neurogenesis, immunomodulation, and the secretion of trophic factors by stem cells from a variety of sources, but the potential mechanisms of action are incompletely understood. In the animal models of stroke, both mesenchymal stem cells (MSCs and neural stem cells (NSCs improve functional recovery, and MSCs reduce the infarct volume when administered acutely, but the heterogeneity in the choice of assessment scales, publication bias, and the possible confounding effects of immunosuppressants make the comparison of effects across cell types difficult. The use of adult-derived cells avoids the ethical issues around embryonic cells but may have more restricted differentiation potential. The use of autologous cells avoids rejection risk, but the sources are restricted, and culture expansion may be necessary, delaying treatment. Allogeneic cells offer controlled cell numbers and immediate availability, which may have advantages for acute treatment. Early clinical trials of both NSCs and MSCs are ongoing, and clinical safety data are emerging from limited numbers of selected patients. Ongoing research to identify prognostic imaging markers may help to improve patient selection, and the novel imaging techniques may identify biomarkers of recovery and the mechanism of action for cell

  14. Stem cells for cardiac repair: an introduction

    Institute of Scientific and Technical Information of China (English)

    Bastiaan C du Pr(e); Pieter A Doevendans; Linda W van Laake

    2013-01-01

    Cardiovascular disease is a major cause of morbidity and mortality throughout the world. Most cardiovascular diseases, such as ischemic heart disease and cardiomyopathy, are associated with loss of functional cardiomyocytes. Unfortunately, the heart has a limited regenerative capacity and is not able to replace these cardiomyocytes once lost. In recent years, stem cells have been put forward as a potential source for cardiac regeneration. Pre-clinical studies that use stem cell-derived cardiac cells show promising results. The mechanisms, though, are not well understood, results have been variable, sometimes transient in the long term, and often without a mechanistic explanation. There are still several major hurdles to be taken. Stem cell-derived cardiac cells should resemble original cardiac cell types and be able to integrate in the damaged heart. Integration requires administration of stem cell-derived cardiac cells at the right time using the right mode of delivery. Once delivered, transplanted cells need vascularization, electrophysiological coupling with the injured heart, and prevention of immunological rejection. Finally, stem cell therapy needs to be safe, reproducible, and affordable. In this review, we will give an introduction to the principles of stem cell based cardiac repair.

  15. Induced pluripotent stem cells for cardiac repair.

    Science.gov (United States)

    Zwi-Dantsis, Limor; Gepstein, Lior

    2012-10-01

    Myocardial stem cell therapies are emerging as novel therapeutic paradigms for myocardial repair, but are hampered by the lack of sources for autologous human cardiomyocytes. An exciting development in the field of cardiovascular regenerative medicine is the ability to reprogram adult somatic cells into pluripotent stem cell lines (induced pluripotent stem cells, iPSCs) and to coax their differentiation into functional cardiomyocytes. This technology holds great promise for the emerging disciplines of personalized and regenerative medicine, because of the ability to derive patient-specific iPSCs that could potentially elude the immune system. The current review describes the latest techniques of generating iPSCs as well as the methods used to direct their differentiation towards the cardiac lineage. We then detail the unique potential as well as the possible hurdles on the road to clinical utilizing of the iPSCs derived cardiomyocytes in the emerging field of cardiovascular regenerative medicine.

  16. Airborne polycyclic aromatic hydrocarbons trigger human skin cells aging through aryl hydrocarbon receptor.

    Science.gov (United States)

    Qiao, Yuan; Li, Qiang; Du, Hong-Yang; Wang, Qiao-Wei; Huang, Ye; Liu, Wei

    2017-07-01

    Accumulating evidence suggests that polycyclic aromatic hydrocarbons (PAH) which adsorbed on the surface of ambient air particulate matters (PM), are the major toxic compound to cause cardiovascular and respiratory diseases, even cancer. However, its detrimental effects on human skin cell remain unclear. Here, we demonstrated that SRM1649b, a reference urban dust material of PAH, triggers human skin cells aging through cell cycle arrest, cell growth inhibition and apoptosis. Principally, SRM1649b facilitated Aryl hydrocarbon receptor (AhR) translocated into nucleus, subsequently activated ERK/MAPK signaling pathway, and upregulated aging-related genes expression. Most important, we found that AhR antagonist efficiently revert the aging of skin cells. Thus our novel findings firstly revealed the mechanism of skin aging under PAH contamination and provided potential strategy for clinical application. Copyright © 2017. Published by Elsevier Inc.

  17. Strategies for cell engineering in tissue repair.

    Science.gov (United States)

    Brown, R A; Smith, K D; Angus McGrouther, D

    1997-01-01

    Cellular and tissue engineering are new areas of research, currently attracting considerable interest because of the remarkable potential they have for clinical application. Some claims have indeed been dramatic, including the possibility of growing complete, artificial organs, such as the liver. However, amid such long-term aspirations there is the very real possibility that small tissues (artificial grafts) may be fabricated in the near future for use in reconstructive surgery. Logically, we should focus on how it is possible to produce modest, engineered tissues for tissue repair. It is evident that strategies to date either depend on innate information within implanted cells, to reform the target tissue or aim to provide appropriate environmental cues or guidance to direct cell behavior. It is argued here that present knowledge of tissue repair biology points us toward the latter approach, providing external cues which will direct how cells should organize the new tissue. This will be particularly true where we need to reproduce microscopic and ultrastructural features of the original tissue architecture. A number of such cues have been identified, and methods are already available, including substrate chemistry, substrate contact guidance, mechanical loading, and biochemical mediators to provide these cues. Examples of these are already being used with some success to control the formation of tissue structures.

  18. Generating cartilage repair from pluripotent stem cells.

    Science.gov (United States)

    Cheng, Aixin; Hardingham, Timothy E; Kimber, Susan J

    2014-08-01

    The treatment of degeneration and injury of articular cartilage has been very challenging for scientists and surgeons. As an avascular and hypocellular tissue, cartilage has a very limited capacity for self-repair. Chondrocytes are the only cell type in cartilage, in which they are surrounded by the extracellular matrix that they secrete and assemble. Autologous chondrocyte implantation for cartilage defects has achieved good results, but the limited resources and complexity of the procedure have hindered wider application. Stem cells form an alternative to chondrocytes as a source of chondrogenic cells due to their ability to proliferate extensively while retaining the potential for differentiation. Adult stem cells such as mesenchymal stem cells have been differentiated into chondrocytes, but the limitations in their proliferative ability and the heterogeneous cell population hinder their adoption as a prime alternative source for generating chondrocytes. Human embryonic stem cells (hESCs) are attractive as candidates for cell replacement therapy because of their unlimited self-renewal and ability for differentiation into mesodermal derivatives as well as other lineages. In this review, we focus on current protocols for chondrogenic differentiation of ESCs, in particular the chemically defined culture system developed in our lab that could potentially be adapted for clinical application.

  19. Repair and degradation systems in irradiated animal cells

    Energy Technology Data Exchange (ETDEWEB)

    Ivannik, B.P.; Proskuryakov, S.Ya.; Ryabchenko, N.I. (Akademiya Meditsinskikh Nauk SSSR, Obninsk. Nauchno-Issledovatel' skij Inst. Meditsinskoj Radiologii)

    It was shown that primary radiosensitivity of DNA depends on the rate of DNA repair. In Zajdela hepatoma cells, cycloheximide administered immediately or 2 h before irradiation of animals does not influence DNA repair. Cycloheximide administered 4 h before irradiation of rats with a dose of 30 Gy arrests DNA repair in thymocytes and Zajdela hepatoma cells. At the same time, in cells of rat lymph nodes and spleen, under similar conditions, cycloheximide does not influence DNA repair and inhibits the secondary DNA degradation.

  20. DNA repair and radiation sensitivity in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.J.C.; Stackhouse, M. [Los Alamos National Lab., NM (United States); Chen, D.S. [Rochester Univ., NY (United States). Dept. of Radiation Oncology

    1993-02-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  1. DNA repair and radiation sensitivity in mammalian cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D.J.C.; Stackhouse, M. (Los Alamos National Lab., NM (United States)); Chen, D.S. (Rochester Univ., NY (United States). Dept. of Radiation Oncology)

    1993-01-01

    Ionizing radiation induces various types of damage in mammalian cells including DNA single-strand breaks, DNA double-strand breaks (DSB), DNA-protein cross links, and altered DNA bases. Although human cells can repair many of these lesions there is little detailed knowledge of the nature of the genes and the encoded enzymes that control these repair processes. We report here on the cellular and genetic analyses of DNA double-strand break repair deficient mammalian cells. It has been well established that the DNA double-strand break is one of the major lesions induced by ionizing radiation. Utilizing rodent repair-deficient mutant, we have shown that the genes responsible for DNA double-strand break repair are also responsible for the cellular expression of radiation sensitivity. The molecular genetic analysis of DSB repair in rodent/human hybrid cells indicate that at least 6 different genes in mammalian cells are responsible for the repair of radiation-induced DNA double-strand breaks. Mapping and the prospect of cloning of human radiation repair genes are reviewed. Understanding the molecular and genetic basis of radiation sensitivity and DNA repair in man will provide a rational foundation to predict the individual risk associated with radiation exposure and to prevent radiation-induced genetic damage in the human population.

  2. 17{alpha}-Ethinylestradiol hinders nucleotide excision repair in zebrafish liver cells

    Energy Technology Data Exchange (ETDEWEB)

    Notch, Emily G. [Department of Biochemistry, Microbiology and Molecular Biology, University of Maine 5735 Hitchner Hall, Orono, ME 04469 (United States); Mayer, Gregory D., E-mail: greg.mayer@ttu.edu [The Institute of Environmental and Human Health, Texas Tech University, Box 41163, Lubbock, TX 79409-1163 (United States)

    2009-12-13

    Nucleotide excision repair (NER) is the primary mechanism that removes bulky DNA adducts such as those caused by ubiquitous environmental mutagens including benzo(a)pyrene and other polycyclic aromatic hydrocarbons. Recent data suggest that exposure to environmentally relevant concentrations of estrogen decreases hepatic mRNA abundance of several key NER genes in adult zebrafish (Danio rerio). However, the impact of decreased hepatic NER expression on NER function was not investigated in the previous study. The goal of this study was to examine the effect of the potent estrogen receptor agonist 17{alpha}-ethinylestradiol (EE{sub 2}) on rate and magnitude of bulky DNA adduct repair. Here we show that exposure of zebrafish liver (ZFL) cells to physiologically relevant concentrations of EE{sub 2} resulted in reduced ability of ZFL cells to repair damaged DNA in comparison to control cells. Co-exposure to EE{sub 2} and a complete estrogen receptor antagonist (ICI 182,780) also resulted in reduced NER capacity, whereas ICI 182,780 alone did not affect the ability of ZFL cells to repair UV damage. These results indicate that estrogen exposure can decrease cellular NER capacity and that this effect can occur in the presence of an estrogen receptor antagonist, suggesting that EE{sub 2} can affect NER processes through mechanisms other than nuclear estrogen receptor activation.

  3. Conversion of hydrocarbons in solid oxide fuel cells

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Kammer Hansen, K.

    2003-01-01

    Recently, a number of papers about direct oxidation of methane and hydrocarbon in solid oxide fuel cells (SOFC) at relatively low temperatures (about 700degreesC) have been published. Even though the conversion of almost dry CH4 at 1000degreesC on ceramic anodes was demonstrated more than 10 years...

  4. Therapeutic potential of stem cells in auditory hair cell repair

    Directory of Open Access Journals (Sweden)

    Ryuji Hata

    2009-01-01

    Full Text Available The prevalence of acquired hearing loss is very high. About 10% of the total population and more than one third of the population over 65 years suffer from debilitating hearing loss. The most common type of hearing loss in adults is idiopathic sudden sensorineural hearing loss (ISSHL. In the majority of cases, ISSHL is permanent and typically associated with loss of sensory hair cells in the organ of Corti. Following the loss of sensory hair cells, the auditory neurons undergo secondary degeneration. Sensory hair cells and auditory neurons do not regenerate throughout life, and loss of these cells is irreversible and cumulative. However, recent advances in stem cell biology have gained hope that stem cell therapy comes closer to regenerating sensory hair cells in humans. A major advance in the prospects for the use of stem cells to restore normal hearing comes with the recent discovery that hair cells can be generated ex vivo from embryonic stem (ES cells, adult inner ear stem cells and neural stem cells. Furthermore, there is increasing evidence that stem cells can promote damaged cell repair in part by secreting diffusible molecules such as growth factors. These results suggest that stem-cell-based treatment regimens can be applicable to the damaged inner ear as future clinical applications.Previously we have established an animal model of cochlear ischemia in gerbils and showed progressive hair cell loss up to 4 days after ischemia. Auditory brain stem response (ABR recordings have demonstrated that this gerbil model displays severe deafness just after cochlear ischemia and gradually recovers thereafter. These pathological findings and clinical manifestations are reminiscent of ISSHL in humans. In this study, we have shown the effectiveness of stem cell therapy by using this animal model of ISSHL.

  5. Vascular smooth muscle progenitor cells: building and repairing blood vessels.

    Science.gov (United States)

    Majesky, Mark W; Dong, Xiu Rong; Regan, Jenna N; Hoglund, Virginia J

    2011-02-04

    Molecular pathways that control the specification, migration, and number of available smooth muscle progenitor cells play key roles in determining blood vessel size and structure, capacity for tissue repair, and progression of age-related disorders. Defects in these pathways produce malformations of developing blood vessels, depletion of smooth muscle progenitor cell pools for vessel wall maintenance and repair, and aberrant activation of alternative differentiation pathways in vascular disease. A better understanding of the molecular mechanisms that uniquely specify and maintain vascular smooth muscle cell precursors is essential if we are to use advances in stem and progenitor cell biology and somatic cell reprogramming for applications directed to the vessel wall.

  6. Biomaterial and Cell Based Cartilage Repair

    NARCIS (Netherlands)

    Zhao, X

    2015-01-01

    Injuries to human native cartilage tissue are particularly troublesome because cartilage has little ability to heal or regenerate itself. The reconstruction, repair, and regeneration of cartilage tissue continue to be one of the greatest clinical challenges, especially in orthopaedic and plastic sur

  7. Biomaterial and Cell Based Cartilage Repair

    NARCIS (Netherlands)

    Zhao, X

    2015-01-01

    Injuries to human native cartilage tissue are particularly troublesome because cartilage has little ability to heal or regenerate itself. The reconstruction, repair, and regeneration of cartilage tissue continue to be one of the greatest clinical challenges, especially in orthopaedic and plastic

  8. Highly Efficient and Reproducible Nonfullerene Solar Cells from Hydrocarbon Solvents

    KAUST Repository

    Wadsworth, Andrew

    2017-06-01

    With chlorinated solvents unlikely to be permitted for use in solution-processed organic solar cells in industry, there must be a focus on developing nonchlorinated solvent systems. Here we report high-efficiency devices utilizing a low-bandgap donor polymer (PffBT4T-2DT) and a nonfullerene acceptor (EH-IDTBR) from hydrocarbon solvents and without using additives. When mesitylene was used as the solvent, rather than chlorobenzene, an improved power conversion efficiency (11.1%) was achieved without the need for pre- or post-treatments. Despite altering the processing conditions to environmentally friendly solvents and room-temperature coating, grazing incident X-ray measurements confirmed that active layers processed from hydrocarbon solvents retained the robust nanomorphology obtained with hot-processed chlorinated solvents. The main advantages of hydrocarbon solvent-processed devices, besides the improved efficiencies, were the reproducibility and storage lifetime of devices. Mesitylene devices showed better reproducibility and shelf life up to 4000 h with PCE dropping by only 8% of its initial value.

  9. Suppressed expression of non-DSB repair genes inhibits gamma-radiation-induced cytogenetic repair and cell cycle arrest.

    Science.gov (United States)

    Zhang, Ye; Rohde, Larry H; Emami, Kamal; Hammond, Dianne; Casey, Rachael; Mehta, Satish K; Jeevarajan, Antony S; Pierson, Duane L; Wu, Honglu

    2008-11-01

    Changes of gene expression profile are one of the most important biological responses in living cells after ionizing radiation (IR) exposure. Although some studies have shown that genes up-regulated by IR may play important roles in DNA damage repair, the relationship between the regulation of gene expression by IR, particularly genes not known for their roles in double-strand break (DSB) repair, and its impact on cytogenetic responses has not been well studied. The purpose of this study is to identify new roles of IR inducible genes in regulating DSB repair and cell cycle progression. In this study, the expression of 25 genes selected on the basis of their transcriptional changes in response to IR was individually knocked down by small interfering RNA in human fibroblast cells. Frequency of micronuclei (MN) formation and chromosome aberrations were measured to determine efficiency of cytogenetic repair, especially DSB repair. In response to IR, the formation of MN was significantly increased by suppressed expression of five genes: Ku70 (DSB repair pathway), XPA (nucleotide excision repair pathway), RPA1 (mismatch repair pathway), RAD17 and RBBP8 (cell cycle control). Knocked-down expression of four genes (MRE11A, RAD51 in the DSB pathway, SESN1, and SUMO1) significantly inhibited cell cycle progression, possibly because of severe impairment of DNA damage repair. Moreover, decreased XPA, p21, or MLH1 expression resulted in both significantly enhanced cell cycle progression and increased yields of chromosome aberrations, indicating that these gene products modulate both cell cycle control and DNA damage repair. Nine of these eleven genes, whose knock-down expression affected cytogenetic repair, were up-regulated in cells exposed to gamma radiation, suggesting that genes transcriptionally modulated by IR were critical to regulate IR-induced biological consequences. Furthermore, eight non-DBS repair genes showed involvement in regulating DSB repair, indicating that

  10. Bone marrow stromal cell : mediated neuroprotection for spinal cord repair

    NARCIS (Netherlands)

    Ritfeld, Gaby Jane

    2014-01-01

    Currently, there is no treatment available that restores anatomy and function after spinal cord injury. This thesis explores transplantation of bone marrow-derived mesenchymal stem cells (bone marrow stromal cells; BMSCs) as a therapeutic approach for spinal cord repair. BMSCs secrete neurotrophic f

  11. Stem cell-based biological tooth repair and regeneration.

    Science.gov (United States)

    Volponi, Ana Angelova; Pang, Yvonne; Sharpe, Paul T

    2010-12-01

    Teeth exhibit limited repair in response to damage, and dental pulp stem cells probably provide a source of cells to replace those damaged and to facilitate repair. Stem cells in other parts of the tooth, such as the periodontal ligament and growing roots, play more dynamic roles in tooth function and development. Dental stem cells can be obtained with ease, making them an attractive source of autologous stem cells for use in restoring vital pulp tissue removed because of infection, in regeneration of periodontal ligament lost in periodontal disease, and for generation of complete or partial tooth structures to form biological implants. As dental stem cells share properties with mesenchymal stem cells, there is also considerable interest in their wider potential to treat disorders involving mesenchymal (or indeed non-mesenchymal) cell derivatives, such as in Parkinson's disease.

  12. Potentials of Endogenous Neural Stem cells in Cortical Repair

    Directory of Open Access Journals (Sweden)

    Bhaskar eSaha

    2012-04-01

    Full Text Available In the last few decades great thrust has been put in the area of regenerative neurobiology research to combat brain injuries and neurodegenerative diseases. The recent discovery of neurogenic niches in the adult brain has led researchers to study how to mobilize these cells to orchestrate an endogenous repair mechanism. The brain can minimize injury-induced damage by means of an immediate glial response and by initiating repair mechanisms that involve the generation and mobilization of new neurons to the site of injury where they can integrate into the existing circuit. This review highlights the current status of research in this field. Here, we discuss the changes that take place in the neurogenic milieu following injury. We will focus, in particular, on the cellular and molecular controls that lead to increased proliferation in the Sub ventricular Zone (SVZ as well as neurogenesis. We will also concentrate on how these cellular and molecular mechanisms influence the migration of new cells to the affected area and their differentiation into neuronal/glial lineage that initiate the repair mechanism. Next, we will discuss some of the different factors that limit/retard the repair process and highlight future lines of research that can help to overcome these limitations. A clear understanding of the underlying molecular mechanisms and physiological changes following brain damage and the subsequent endogenous repair should help us develop better strategies to repair damaged brains.

  13. Induction of a mutant phenotype in human repair proficient cells after overexpression of a mutated human DNA repair gene.

    NARCIS (Netherlands)

    P.B.G.M. Belt; M.F. van Oostenrijk; H. Odijk (Hanny); J.H.J. Hoeijmakers (Jan); C.M.P. Backendorf (Claude)

    1991-01-01

    textabstractAntisense and mutated cDNA of the human excision repair gene ERCC-1 were overexpressed in repair efficient HeLa cells by means of an Epstein-Barr-virus derived CDNA expression vector. Whereas antisense RNA did not influence the survival of the transfected cells, a mutated cDNA generating

  14. Fate and degradation of petroleum hydrocarbons in stormwater bioretention cells

    Science.gov (United States)

    LeFevre, Gregory Hallett

    This dissertation describes the investigation of the fate of hydrocarbons in stormwater bioretention areas and those mechanisms that affect hydrocarbon fate in such systems. Seventy-five samples from 58 bioretention areas were collected and analyzed to measure total petroleum hydrocarbon (TPH) residual and biodegradation functional genes. TPH residual in bioretention areas was greater than background sites but low overall (biodegradation. Field soils were capable of mineralizing naphthalene, a polycyclic aromatic hydrocarbon (PAH) when incubated in the laboratory. In an additional laboratory investigation, a column study was initiated to comprehensively determine naphthalene fate in a simulated bioretention cell using a 14C-labeled tracer. Sorption to soil was the greatest sink of naphthalene in the columns, although biodegradation and vegetative uptake were also important loss mechanisms. Little leaching occurred following the first flush, and volatilization was insignificant. Significant enrichment of naphthalene degrading bacteria occurred over the course of the experiment as a result of naphthalene exposure. This was evident from enhanced naphthalene biodegradation kinetics (measured via batch tests), significant increases in naphthalene dioxygenase gene quantities, and a significant correlation observed between naphthalene residual and biodegradation functional genes. Vegetated columns outperformed the unplanted control column in terms of total naphthalene removal and biodegradation kinetics. As a result of these experiments, a final study focused on why planted systems outperform unplanted systems was conducted. Plant root exudates were harvested from hydroponic setups for three types of plants. Additionally, a solution of artificial root exudates (AREs) as prepared. Exudates were digested using soil bacteria to create metabolized exudates. Raw and metabolized exudates were characterized for dissolved organic carbon, specific UV absorbance, spectral slope

  15. Tendon repair augmented with a novel circulating stem cell population.

    Science.gov (United States)

    Daher, Robert J; Chahine, Nadeen O; Razzano, Pasquale; Patwa, Sohum A; Sgaglione, Nicholas J; Grande, Daniel A

    2011-01-01

    Tendon ruptures are common sports-related injuries that are often treated surgically by the use of sutures followed by immobilization. However, tendon repair by standard technique is associated with long healing time and often suboptimal repair. Methods to enhance tendon repair time as well as the quality of repair are currently unmet clinical needs. Our hypothesis is that the introduction of a unique stem cell population at the site of tendon transection would result in an improved rate and quality of repair. Achilles tendons of fifty-one Sprague-Dawley rats were transected and suture-repaired. In half of the rats, a biodegradable scaffold seeded with allogenic circulating stem cells was placed as an onlay to the defect site in addition to the suture repair. The other half was treated with suture alone to serve as the control group. Animals were randomized to a two-, four-, or six-week time group. At the time of necropsy, tendons were harvested and prepared for either biomechanical or histological analysis. Histological slides were evaluated in a blinded fashion with the use of a grading scale. By two weeks, the experimental group demonstrated a significant improvement in repair compared to controls with no failures. Average histological scores of 0.6 and 2.6 were observed for the experimental and control group respectively. The experimental group demonstrated complete bridging of the transection site with parallel collagen fiber arrangement. By four weeks, both groups showed a continuing trend of healing, with the scaffold group exceeding the histological quality of the tissue repaired with suture alone. Biomechanically, the experimental group had a decreasing cross-sectional area with time which was also associated with a significant increase in the ultimate tensile strength of the tendons, reaching 4.2MPa by six weeks. The experimental group also achieved a significantly higher elastic toughness by six weeks and saw an increase in the tensile modulus, reaching

  16. Bone-Marrow-Derived Mesenchymal Stem Cells for Organ Repair

    Directory of Open Access Journals (Sweden)

    Ming Li

    2013-01-01

    Full Text Available Mesenchymal stem cells (MSCs are prototypical adult stem cells with the capacity for self-renewal and differentiation with a broad tissue distribution. MSCs not only differentiate into types of cells of mesodermal lineage but also into endodermal and ectodermal lineages such as bone, fat, cartilage and cardiomyocytes, endothelial cells, lung epithelial cells, hepatocytes, neurons, and pancreatic islets. MSCs have been identified as an adherent, fibroblast-like population and can be isolated from different adult tissues, including bone marrow (BM, umbilical cord, skeletal muscle, and adipose tissue. MSCs secrete factors, including IL-6, M-CSF, IL-10, HGF, and PGE2, that promote tissue repair, stimulate proliferation and differentiation of endogenous tissue progenitors, and decrease inflammatory and immune reactions. In this paper, we focus on the role of BM-derived MSCs in organ repair.

  17. Ku80-deleted cells are defective at base excision repair

    Energy Technology Data Exchange (ETDEWEB)

    Li, Han [The University of Texas Health Science Center at San Antonio, The Institute of Biotechnology, The Department of Molecular Medicine, 15355 Lambda Drive, San Antonio, TX 78245-3207 (United States); Tumor Suppression Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029 (Spain); Marple, Teresa [The University of Texas Health Science Center at San Antonio, The Institute of Biotechnology, The Department of Molecular Medicine, 15355 Lambda Drive, San Antonio, TX 78245-3207 (United States); Hasty, Paul, E-mail: hastye@uthscsa.edu [The University of Texas Health Science Center at San Antonio, The Institute of Biotechnology, The Department of Molecular Medicine, 15355 Lambda Drive, San Antonio, TX 78245-3207 (United States); Tumor Suppression Group, Spanish National Cancer Research Centre (CNIO), Madrid 28029 (Spain)

    2013-05-15

    Graphical abstract: - Highlights: • Ku80-deleted cells are hypersensitive to ROS and alkylating agents. • Cells deleted for Ku80, but not Ku70 or Lig4, have reduced BER capacity. • OGG1 rescues hypersensitivity to H{sub 2}O{sub 2} and paraquat in Ku80-mutant cells. • Cells deleted for Ku80, but not Lig4, are defective at repairing AP sites. • Cells deleted for Ku80, but not Lig4 or Brca2 exon 27, exhibit increased PAR. - Abstract: Ku80 forms a heterodimer with Ku70, called Ku, that repairs DNA double-strand breaks (DSBs) via the nonhomologous end joining (NHEJ) pathway. As a consequence of deleting NHEJ, Ku80-mutant cells are hypersensitive to agents that cause DNA DSBs like ionizing radiation. Here we show that Ku80 deletion also decreased resistance to ROS and alkylating agents that typically cause base lesions and single-strand breaks (SSBs). This is unusual since base excision repair (BER), not NHEJ, typically repairs these types of lesions. However, we show that deletion of another NHEJ protein, DNA ligase IV (Lig4), did not cause hypersensitivity to these agents. In addition, the ROS and alkylating agents did not induce γ-H2AX foci that are diagnostic of DSBs. Furthermore, deletion of Ku80, but not Lig4 or Ku70, reduced BER capacity. Ku80 deletion also impaired BER at the initial lesion recognition/strand scission step; thus, involvement of a DSB is unlikely. Therefore, our data suggests that Ku80 deletion impairs BER via a mechanism that does not repair DSBs.

  18. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A. Jolt; Blom, Paul W.m.; Michels, Jasper J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium

  19. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A. Jolt; Blom, Paul W.m.; Michels, Jasper J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypo

  20. Repair of defects in photoactive layer of organic solar cells

    NARCIS (Netherlands)

    Oostra, A.J.; Blom, P.W.M.; Michels, J.J.

    2015-01-01

    Defects occurring during printing of the photoactive layer in organic solar cells lead to short-circuits due to direct contact between the PEDOT:PSS anode and metallic cathode. We provide a highly effective repair method where the defected zone with bare PEDOT:PSS is treated with aqueous sodium hypo

  1. Stem cell transplantation enhances endogenous brain repair after experimental stroke.

    Science.gov (United States)

    Horie, Nobutaka; Hiu, Takeshi; Nagata, Izumi

    2015-01-01

    Stem cell transplantation for stroke treatment has been a promising therapy in small and large animal models, and many clinical trials are ongoing to establish this strategy in a clinical setting. However, the mechanism underlying functional recovery after stem cell transplantation has not been fully established and there is still a need to determine the ideal subset of stem cells for such therapy. We herein reviewed the recent evidences showing the underlying mechanism of functional recovery after cell transplantation, focusing on endogenous brain repair. First, angiogenesis/neovascularization is promoted by trophic factors including vascular endothelial growth factor secreted from stem cells, and stem cells migrated to the lesion along with the vessels. Second, axonal sprouting, dendritic branching, and synaptogenesis were enhanced altogether in the both ipsilateral and contralateral hemisphere remapping the pyramidal tract across the board. Finally, endogenous neurogenesis was also enhanced although little is known how much these neurogenesis contribute to the functional recovery. Taken together, it is clear that stem cell transplantation provides functional recovery via endogenous repair enhancement from multiple ways. This is important to maximize the effect of stem cell therapy after stroke, although it is still undetermined which repair mechanism is mostly contributed.

  2. IMPLICATIONS OF MICROBIAL ADHESION TO HYDROCARBONS FOR EVALUATING CELL-SURFACE HYDROPHOBICITY .1. ZETA-POTENTIALS OF HYDROCARBON DROPLETS

    NARCIS (Netherlands)

    BUSSCHER, HJ; VANDEBELTGRITTER, B; VANDERMEI, HC

    1995-01-01

    Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. As microbial adhesion is a complicated interplay of long-range van der Waals and electrostatic forces and various short-range interactions, the above statement only holds

  3. Human embryonic stem cells for neuronal repair.

    Science.gov (United States)

    Ben-Hur, Tamir

    2006-02-01

    Human embryonic stem cells may serve as a potentially endeless source of transplantable cells to treat various neurologic disorders. Accumulating data have shown the therapeutic value of various neural precursor cell types in experimental models of neurologic diseases. Tailoring cell therapy for specific disorders requires the generation of cells that are committed to specific neural lineages. To this end, protocols were recently developed for the derivation of dopaminergic neurons, spinal motor neurons and oligodendrocytes from hESC. These protocols recapitulate normal development in culture conditions. However, a novel concept emerging from these studies is that the beneficial effect of transplanted stem cells is not only via cell replacement in damaged host tissue, but also by trophic and protective effects, as well as by an immunomodulatory effect that down-regulates detrimental brain inflammation.

  4. Activation of Type II Cells into Regenerative Stem Cell Antigen-1+ Cells during Alveolar Repair

    Science.gov (United States)

    Kumar, Varsha Suresh; Zhang, Wei; Rehman, Jalees; Malik, Asrar B.

    2015-01-01

    The alveolar epithelium is composed of two cell types: type I cells comprise 95% of the gas exchange surface area, whereas type II cells secrete surfactant, while retaining the ability to convert into type I cells to induce alveolar repair. Using lineage-tracing analyses in the mouse model of Pseudomonas aeruginosa–induced lung injury, we identified a population of stem cell antigen (Sca)-1–expressing type II cells with progenitor cell properties that mediate alveolar repair. These cells were shown to be distinct from previously reported Sca-1–expressing bronchioalveolar stem cells. Microarray and Wnt reporter studies showed that surfactant protein (Sp)-C+Sca-1+ cells expressed Wnt signaling pathway genes, and inhibiting Wnt/β-catenin signaling prevented the regenerative function of Sp-C+Sca-1+ cells in vitro. Thus, P. aeruginosa–mediated lung injury induces the generation of a Sca-1+ subset of type II cells. The progenitor phenotype of the Sp-C+Sca-1+ cells that mediates alveolar epithelial repair might involve Wnt signaling. PMID:25474582

  5. Development of direct hydrocarbon solid oxide fuel cells

    Science.gov (United States)

    McIntosh, Steven

    The focus of this dissertation is the development of a Solid Oxide Fuel Cell (SOFC) that can operate with hydrocarbon fuels without the need for pre-reforming. The design of an active SOFC anode requires the consideration of a number of factors including the catalytic activity of the electrode towards fuel oxidation and electronic conductivity. This work focuses on a novel system for anode fabrication that allows the catalytically active and electronically conducting components of the anode to be easily varied. The catalytic properties of the SOFC anode were examined and a strong link between SOFC performance and oxidation activity demonstrated. Of the rare-earth catalysts investigated ceria was found to have the highest activity leading to the highest fuel cell power density. This activity was further improved, especially for methane fuel, by doping with a precious metal. Furthermore, it was shown that the catalyst not only increased the rate of reaction but increased the cell Open-Circuit Voltage (OCV) suggesting a change in mechanism that increased the cell efficiency. The necessity for high electronic conductivity and connectivity in the electrode was elucidated by studying the impact of anode copper content on cell performance. Low copper loading led to reduced cell performance due to a lack of conductive pathways from the active electrode region to the external circuit. It was observed that additional conductivity was provided by a thermally deposited carbonaceous phase formed upon exposure to hydrocarbon fuels. The electrochemical characterization of SOFC electrodes is a non-trivial problem. Literature reports on the properties of similar electrodes are inconsistent and often contradictory. Using a combined experimental and theoretical approach, significant problems were found with common experimental procedures used to separate the losses associated the cell cathode from those of the anode. By calculating the effect of test geometry on this separation, it

  6. Stem cell death and survival in heart regeneration and repair.

    Science.gov (United States)

    Abdelwahid, Eltyeb; Kalvelyte, Audrone; Stulpinas, Aurimas; de Carvalho, Katherine Athayde Teixeira; Guarita-Souza, Luiz Cesar; Foldes, Gabor

    2016-03-01

    Cardiovascular diseases are major causes of mortality and morbidity. Cardiomyocyte apoptosis disrupts cardiac function and leads to cardiac decompensation and terminal heart failure. Delineating the regulatory signaling pathways that orchestrate cell survival in the heart has significant therapeutic implications. Cardiac tissue has limited capacity to regenerate and repair. Stem cell therapy is a successful approach for repairing and regenerating ischemic cardiac tissue; however, transplanted cells display very high death percentage, a problem that affects success of tissue regeneration. Stem cells display multipotency or pluripotency and undergo self-renewal, however these events are negatively influenced by upregulation of cell death machinery that induces the significant decrease in survival and differentiation signals upon cardiovascular injury. While efforts to identify cell types and molecular pathways that promote cardiac tissue regeneration have been productive, studies that focus on blocking the extensive cell death after transplantation are limited. The control of cell death includes multiple networks rather than one crucial pathway, which underlies the challenge of identifying the interaction between various cellular and biochemical components. This review is aimed at exploiting the molecular mechanisms by which stem cells resist death signals to develop into mature and healthy cardiac cells. Specifically, we focus on a number of factors that control death and survival of stem cells upon transplantation and ultimately affect cardiac regeneration. We also discuss potential survival enhancing strategies and how they could be meaningful in the design of targeted therapies that improve cardiac function.

  7. Stem cells for brain repair and recovery after stroke.

    Science.gov (United States)

    Gutiérrez-Fernández, María; Rodríguez-Frutos, Berta; Ramos-Cejudo, Jaime; Otero-Ortega, Laura; Fuentes, Blanca; Díez-Tejedor, Exuperio

    2013-11-01

    Stroke is a major worldwide cause of death and disability. Currently, intravenous thrombolysis and reperfusion therapies, but not the so-called neuroprotectant drugs, have been shown to be effective for acute ischemic stroke. Thus, new strategies to promote brain plasticity are necessary. Stem cell administration is an attractive future therapeutic approach. Brain protection and repair mechanisms are activated after stroke. This article is focused on the capacity of stem cell-based therapy to enhance this postinfarct brain plasticity and recovery. Future therapeutic considerations and prospects for stroke are discussed. Although cell therapy is promising in stroke treatment, mechanisms of action need to be characterized in detail. Further, the different mechanisms of axonal plasticity and remodeling involucrated in brain repair, not only in the gray but also in white matter, must be investigated through noninvasive techniques, and a multidisciplinary approach is fundamental in this.

  8. Sister chromatid gene conversion is a prominent double-strand break repair pathway in mammalian cells

    OpenAIRE

    Johnson, Roger D.; Jasin, Maria

    2000-01-01

    In mammalian cells, repair of DNA double-strand breaks (DSBs) occurs by both homologous and non-homologous mechanisms. By definition, homologous recombination requires a template with sufficient sequence identity to the damaged molecule in order to direct repair. We now show that the sister chromatid acts as a repair template in a substantial proportion of DSB repair events. The outcome of sister chromatid repair is primarily gene conversion unassociated with reciprocal exchange. This contras...

  9. Difference in Membrane Repair Capacity Between Cancer Cell Lines and a Normal Cell Line.

    Science.gov (United States)

    Frandsen, Stine Krog; McNeil, Anna K; Novak, Ivana; McNeil, Paul L; Gehl, Julie

    2016-08-01

    Electroporation-based treatments and other therapies that permeabilize the plasma membrane have been shown to be more devastating to malignant cells than to normal cells. In this study, we asked if a difference in repair capacity could explain this observed difference in sensitivity. Membrane repair was investigated by disrupting the plasma membrane using laser followed by monitoring fluorescent dye entry over time in seven cancer cell lines, an immortalized cell line, and a normal primary cell line. The kinetics of repair in living cells can be directly recorded using this technique, providing a sensitive index of repair capacity. The normal primary cell line of all tested cell lines exhibited the slowest rate of dye entry after laser disruption and lowest level of dye uptake. Significantly, more rapid dye uptake and a higher total level of dye uptake occurred in six of the seven tested cancer cell lines (p normal cell line (98 % viable cells) was higher than in the three tested cancer cell lines (81-88 % viable cells). These data suggest more effective membrane repair in normal, primary cells and supplement previous explanations why electroporation-based therapies and other therapies permeabilizing the plasma membrane are more effective on malignant cells compared to normal cells in cancer treatment.

  10. Role of neural precursor cells in promoting repair following stroke

    Institute of Scientific and Technical Information of China (English)

    Pooya DIBAJNIA; Cindi M MORSHEAD

    2013-01-01

    Stem cell-based therapies for the treatment of stroke have received considerable attention.Two broad approaches to stem cell-based therapies have been taken:the transplantation of exogenous stem cells,and the activation of endogenous neural stem and progenitor cells (together termed neural precursors).Studies examining the transplantation of exogenous cells have demonstrated that neural stem and progenitor cells lead to the most clinically promising results.Endogenous activation of neural precursors has also been explored based on the fact that resident precursor cells have the inherent capacity to proliferate,migrate and differentiate into mature neurons in the uninjured adult brain.Studies have revealed that these neural precursor cell behaviours can be activated following stroke,whereby neural precursors will expand in number,migrate to the infarct site and differentiate into neurons.However,this innate response is insufficient to lead to functional recovery,making it necessary to enhance the activation of endogenous precursors to promote tissue repair and functional recovery.Herein we will discuss the current state of the stem cell-based approaches with a focus on endogenous repair to treat the stroke injured brain.

  11. Cell lineages, growth and repair of the mouse heart.

    Science.gov (United States)

    Lescroart, Fabienne; Meilhac, Sigolène M

    2012-01-01

    The formation of the heart involves diversification of lineages which differentiate into distinct cardiac cell types or contribute to different regions such as the four cardiac chambers. The heart is the first organ to form in the embryo. However, in parallel with the growth of the organism, before or after birth, the heart has to adapt its size to maintain pumping efficiency. The adult heart has only a mild regeneration potential; thus, strategies to repair the heart after injury are based on the mobilisation of resident cardiac stem cells or the transplantation of external sources of stem cells. We discuss current knowledge on these aspects and raise questions for future research.

  12. Difference in membrane repair capacity between cancer cell lines and a normal cell line

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; McNeil, Anna K.; Novak, Ivana

    2016-01-01

    Electroporation-based treatments and other therapies that permeabilize the plasma membrane have been shown to be more devastating to malignant cells than to normal cells. In this study, we asked if a difference in repair capacity could explain this observed difference in sensitivity. Membrane...... repair was investigated by disrupting the plasma membrane using laser followed by monitoring fluorescent dye entry over time in seven cancer cell lines, an immortalized cell line, and a normal primary cell line. The kinetics of repair in living cells can be directly recorded using this technique...... cancer cell lines (p cell line (p membrane permeabilization by electroporation. Viability in the primary normal cell line (98 % viable cells) was higher...

  13. Dental stem cells for tooth regeneration and repair.

    Science.gov (United States)

    Mantesso, Andrea; Sharpe, Paul

    2009-09-01

    Mesenchymal stem cells (MSCs) resident in bone marrow are one of the most studied and clinically important populations of adult stem cells. Cells with, similar properties to these MSCs have been described in several different tooth tissues and the potential ease with which these dental MSCs could be obtained from patients has prompted great interest in these cells as a source of MSCs for cell-based therapeutics. In this review we address the current state of knowledge regarding these cells, their properties, origins, locations, functions and potential uses in tooth tissue engineering and repair. We discuss some of the key controversies and outstanding issues, not least of which whether dental stem cells actually exist.

  14. IMPLICATIONS OF MICROBIAL ADHESION TO HYDROCARBONS FOR EVALUATING CELL-SURFACE HYDROPHOBICITY .2. ADHESION MECHANISMS

    NARCIS (Netherlands)

    VANDERMEI, HC; VANDEBELTGRITTER, B; BUSSCHER, HJ

    1995-01-01

    Microbial adhesion to hydrocarbons (MATH) is generally considered to be a measure of the organisms cell surface hydrophobicity. Recent observations that the zeta potentials of hydrocarbons can be highly negative in the various solutions commonly used in MATH, have suggested that MATH may measure a

  15. Stem cells for brain repair in neonatal hypoxia-ischemia.

    Science.gov (United States)

    Chicha, L; Smith, T; Guzman, R

    2014-01-01

    Neonatal hypoxic-ischemic insults are a significant cause of pediatric encephalopathy, developmental delays, and spastic cerebral palsy. Although the developing brain's plasticity allows for remarkable self-repair, severe disruption of normal myelination and cortical development upon neonatal brain injury are likely to generate life-persisting sensory-motor and cognitive deficits in the growing child. Currently, no treatments are available that can address the long-term consequences. Thus, regenerative medicine appears as a promising avenue to help restore normal developmental processes in affected infants. Stem cell therapy has proven effective in promoting functional recovery in animal models of neonatal hypoxic-ischemic injury and therefore represents a hopeful therapy for this unmet medical condition. Neural stem cells derived from pluripotent stem cells or fetal tissues as well as umbilical cord blood and mesenchymal stem cells have all shown initial success in improving functional outcomes. However, much still remains to be understood about how those stem cells can safely be administered to infants and what their repair mechanisms in the brain are. In this review, we discuss updated research into pathophysiological mechanisms of neonatal brain injury, the types of stem cell therapies currently being tested in this context, and the potential mechanisms through which exogenous stem cells might interact with and influence the developing brain.

  16. Nuclear envelope rupture and repair during cancer cell migration

    Science.gov (United States)

    Denais, Celine M.; Gilbert, Rachel M.; Isermann, Philipp; McGregor, Alexandra L.; te Lindert, Mariska; Weigelin, Bettina; Davidson, Patricia M.; Friedl, Peter; Wolf, Katarina; Lammerding, Jan

    2016-01-01

    During cancer metastasis, tumor cells penetrate tissues through tight interstitial spaces, requiring extensive deformation of the cell and its nucleus. Here, we investigated tumor cell migration in confining microenvironments in vitro and in vivo. Nuclear deformation caused localized loss of nuclear envelope (NE) integrity, which led to the uncontrolled exchange of nucleo-cytoplasmic content, herniation of chromatin across the NE, and DNA damage. The incidence of NE rupture increased with cell confinement and with depletion of nuclear lamins, NE proteins that structurally support the nucleus. Cells restored NE integrity using components of the endosomal sorting complexes required for transport-III (ESCRT-III) machinery. Our findings indicate that cell migration incurs substantial physical stress on the NE and its content, requiring efficient NE and DNA damage repair for survival. PMID:27013428

  17. Renal tubule cell repair following acute renal injury.

    Science.gov (United States)

    Humes, H D; Lake, E W; Liu, S

    1995-01-01

    Experimental data suggests the recovery of renal function after ischemic or nephrotoxic acute renal failure is due to a replicative repair process dependent upon predominantly paracrine release of growth factors. These growth factors promote renal proximal tubule cell proliferation and a differentiation phase dependent on the interaction between tubule cells and basement membrane. These insights identify the molecular basis of renal repair and ischemic and nephrotoxic acute renal failure, and may lead to potential therapeutic modalities that accelerate renal repair and lessen the morbidity and mortality associated with these renal disease processes. In this regard, there is a prominent vasoconstrictor response of the renal vasculature during the postischemic period of developing acute renal failure. The intravenous administration of pharmacologic doses of atrial natriuretic factor (ANF) in the postischemic period have proven efficacious by altering renal vascular resistance, so that renal blood flow and glomerular filtration rate improve. ANF also appears to protect renal tubular epithelial integrity and holds significant promise as a therapeutic agent in acute renal failure. Of equal or greater promise are the therapeutic interventions targeting the proliferative reparative zone during the postischemic period. The exogenous administration of epidermal growth factor or insulin-like growth factor-1 in the postischemic period have effectively decreased the degree of renal insufficiency as measured by the peak serum creatinine and has hastened renal recovery as measured by the duration of time required to return the baseline serum creatinine values. A similarly efficacious role for hepatocyte growth factor has also been recently demonstrated.

  18. Effect of failures and repairs on multiple cell production lines

    Energy Technology Data Exchange (ETDEWEB)

    Legato, P.; Bobbio, A.; Roberti, L.

    1989-01-01

    This paper examines a production line composed of multiple stages, or cells, which are passed in sequential order to arrive to the final product. Two possible coordination disciplines are considered, namely: the classical tandem arrangement of sequential working centers with input buffer and the kanban scheme, considered the Japanese shop floor realization of the Just-In-Time (JIT) manifacturing approach. The production line is modelled and analysed by means of Stochastic Petri Nets (SPN). Finally an analysis is made of the possibility that the working cells can incur failure/repair cycles perturbing the production flow of the line and thus reduce performance indices.

  19. Performance comparison of autothermal reforming for liquid hydrocarbons, gasoline and diesel for fuel cell applications

    Science.gov (United States)

    Kang, Inyong; Bae, Joongmyeon; Bae, Gyujong

    This paper discusses the reforming of liquid hydrocarbons to produce hydrogen for fuel cell applications, focusing on gasoline and diesel due to their high hydrogen density and well-established infrastructures. Gasoline and diesel are composed of numerous hydrocarbon species including paraffins, olefins, cycloparaffins, and aromatics. We have investigated the reforming characteristics of several representative liquid hydrocarbons. In the case of paraffin reforming, H 2 yield and reforming efficiency were close to thermodynamic equilibrium status (TES), although heavier hydrocarbons required slightly higher temperatures than lighter hydrocarbons. However, the conversion efficiency was much lower for aromatics than paraffins with similar carbon number. We have also investigated the reforming performance of simulated commercial diesel and gasoline using simple synthetic diesel and gasoline compositions. Reforming performances of our formulations were in good agreement with those of commercial fuels. In addition, the reforming of gas to liquid (GTL) resulted in high H 2 yield and reforming efficiency showing promise for possible fuel cell applications.

  20. Non-DBS DNA Repair Genes Regulate Radiation-induced Cytogenetic Damage Repair and Cell Cycle Progression

    Science.gov (United States)

    Zhang, Ye; Rohde, Larry H.; Emami, Kamal; Casey, Rachael; Wu, Honglu

    2008-01-01

    Changes of gene expression profile are one of the most important biological responses in living cells after ionizing radiation (IR) exposure. Although some studies have shown that genes up-regulated by IR may play important roles in DNA damage repair, the relationship between the regulation of gene expression by IR, particularly genes not known for their roles in DSB repair, and its impact on cytogenetic responses has not been systematically studied. In the present study, the expression of 25 genes selected on the basis of their transcriptional changes in response to IR was individually knocked down by transfection with small interfering RNA in human fibroblast cells. The purpose of this study is to identify new roles of these selected genes on regulating DSB repair and cell cycle progression , as measured in the micronuclei formation and chromosome aberration. In response to IR, the formation of MN was significantly increased by suppressed expression of 5 genes: Ku70 in the DSB repair pathway, XPA in the NER pathway, RPA1 in the MMR pathway, and RAD17 and RBBP8 in cell cycle control. Knocked-down expression of 4 genes (MRE11A, RAD51 in the DSB pathway, SESN1, and SUMO1) significantly inhibited cell cycle progression, possibly because of severe impairment of DNA damage repair. Furthermore, loss of XPA, P21, or MLH1 expression resulted in both significantly enhanced cell cycle progression and increased yields of chromosome aberrations, indicating that these gene products modulate both cell cycle control and DNA damage repair. Most of the 11 genes that affected cytogenetic responses are not known to have clear roles influencing DBS repair. Nine of these 11 genes were up-regulated in cells exposed to gamma radiation, suggesting that genes transcriptionally modulated by IR were critical to regulate the biological consequences after IR.

  1. Non-DBS DNA Repair Genes Regulate Radiation-induced Cytogenetic Damage Repair and Cell Cycle Progression

    Science.gov (United States)

    Zhang, Ye; Rohde, Larry H.; Emami, Kamal; Casey, Rachael; Wu, Honglu

    2008-01-01

    Changes of gene expression profile are one of the most important biological responses in living cells after ionizing radiation (IR) exposure. Although some studies have shown that genes up-regulated by IR may play important roles in DNA damage repair, the relationship between the regulation of gene expression by IR, particularly genes not known for their roles in DSB repair, and its impact on cytogenetic responses has not been systematically studied. In the present study, the expression of 25 genes selected on the basis of their transcriptional changes in response to IR was individually knocked down by transfection with small interfering RNA in human fibroblast cells. The purpose of this study is to identify new roles of these selected genes on regulating DSB repair and cell cycle progression , as measured in the micronuclei formation and chromosome aberration. In response to IR, the formation of MN was significantly increased by suppressed expression of 5 genes: Ku70 in the DSB repair pathway, XPA in the NER pathway, RPA1 in the MMR pathway, and RAD17 and RBBP8 in cell cycle control. Knocked-down expression of 4 genes (MRE11A, RAD51 in the DSB pathway, SESN1, and SUMO1) significantly inhibited cell cycle progression, possibly because of severe impairment of DNA damage repair. Furthermore, loss of XPA, P21, or MLH1 expression resulted in both significantly enhanced cell cycle progression and increased yields of chromosome aberrations, indicating that these gene products modulate both cell cycle control and DNA damage repair. Most of the 11 genes that affected cytogenetic responses are not known to have clear roles influencing DBS repair. Nine of these 11 genes were up-regulated in cells exposed to gamma radiation, suggesting that genes transcriptionally modulated by IR were critical to regulate the biological consequences after IR.

  2. Aryl hydrocarbon receptor protects lung adenocarcinoma cells against cigarette sidestream smoke particulates-induced oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Ya-Hsin [Graduate Institute of Basic Medical Science, School of Medicine, China Medical University, Taichung 40402, Taiwan, ROC (China); Huang, Su-Chin; Lin, Chun-Ju; Cheng, Li-Chuan [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan, ROC (China); Li, Lih-Ann, E-mail: lihann@nhri.org.tw [Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Zhunan, Miaoli 35053, Taiwan, ROC (China)

    2012-03-15

    Environmental cigarette smoke has been suggested to promote lung adenocarcinoma progression through aryl hydrocarbon receptor (AhR)-signaled metabolism. However, whether AhR facilitates metabolic activation or detoxification in exposed adenocarcinoma cells remains ambiguous. To address this question, we have modified the expression level of AhR in two human lung adenocarcinoma cell lines and examined their response to an extract of cigarette sidestream smoke particulates (CSSP). We found that overexpression of AhR in the CL1-5 cell line reduced CSSP-induced ROS production and oxidative DNA damage, whereas knockdown of AhR expression increased ROS level in CSSP-exposed H1355 cells. Oxidative stress sensor Nrf2 and its target gene NQO1 were insensitive to AhR expression level and CSSP treatment in human lung adenocarcinoma cells. In contrast, induction of AhR expression concurrently increased mRNA expression of xenobiotic-metabolizing genes CYP1B1, UGT1A8, and UGT1A10 in a ligand-independent manner. It appeared that AhR accelerated xenobiotic clearing and diminished associated oxidative stress by coordinate regulation of a set of phase I and II metabolizing genes. However, the AhR-signaled protection could not shield cells from constant oxidative stress. Prolonged exposure to high concentrations of CSSP induced G0/G1 cell cycle arrest via the p53–p21–Rb1 signaling pathway. Despite no effect on DNA repair rate, AhR facilitated the recovery of cells from growth arrest when CSSP exposure ended. AhR-overexpressing lung adenocarcinoma cells exhibited an increased anchorage-dependent and independent proliferation when recovery from exposure. In summary, our data demonstrated that AhR protected lung adenocarcinoma cells against CSSP-induced oxidative stress and promoted post-exposure clonogenicity. -- Highlights: ► AhR expression level influences cigarette sidestream smoke-induced ROS production. ► AhR reduces oxidative stress by coordinate regulation of

  3. Stem Cells in Tooth Development, Growth, Repair, and Regeneration.

    Science.gov (United States)

    Yu, Tian; Volponi, Ana Angelova; Babb, Rebecca; An, Zhengwen; Sharpe, Paul T

    2015-01-01

    Human teeth contain stem cells in all their mesenchymal-derived tissues, which include the pulp, periodontal ligament, and developing roots, in addition to the support tissues such as the alveolar bone. The precise roles of these cells remain poorly understood and most likely involve tissue repair mechanisms but their relative ease of harvesting makes teeth a valuable potential source of mesenchymal stem cells (MSCs) for therapeutic use. These dental MSC populations all appear to have the same developmental origins, being derived from cranial neural crest cells, a population of embryonic stem cells with multipotential properties. In rodents, the incisor teeth grow continuously throughout life, a feature that requires populations of continuously active mesenchymal and epithelial stem cells. The discrete locations of these stem cells in the incisor have rendered them amenable for study and much is being learnt about the general properties of these stem cells for the incisor as a model system. The incisor MSCs appear to be a heterogeneous population consisting of cells from different neural crest-derived tissues. The epithelial stem cells can be traced directly back in development to a Sox10(+) population present at the time of tooth initiation. In this review, we describe the basic biology of dental stem cells, their functions, and potential clinical uses.

  4. Differential repair of UV damage in Saccharomyces cerevisiae is cell cycle dependent.

    Science.gov (United States)

    Terleth, C; Waters, R; Brouwer, J; van de Putte, P

    1990-09-01

    In the yeast Saccharomyces cerevisiae the transcriptionally active MAT alpha locus is repaired preferentially to the inactive HML alpha locus after UV irradiation. Here we analysed the repair of both loci after irradiating yeast cells at different stages of the mitotic cell cycle. In all stages repair of the active MAT alpha locus occurs at a rate of 30% removal of dimers per hour after a UV dose of 60 J/m2. The inactive HML alpha is repaired as efficiently as MAT alpha following irradiation in G2 whereas repair of HML alpha is less efficient in the other stages. Thus differential repair is observed in G1 and S but not in G2. Apparently, in G2 a chromatin structure exists in which repair does not discriminate between transcriptionally active and inactive DNA or, alternatively, an additional repair mechanism might exist which is only operational during G2.

  5. Skin appendage-derived stem cells: cell biology and potential for wound repair.

    Science.gov (United States)

    Xie, Jiangfan; Yao, Bin; Han, Yutong; Huang, Sha; Fu, Xiaobing

    2016-01-01

    Stem cells residing in the epidermis and skin appendages are imperative for skin homeostasis and regeneration. These stem cells also participate in the repair of the epidermis after injuries, inducing restoration of tissue integrity and function of damaged tissue. Unlike epidermis-derived stem cells, comprehensive knowledge about skin appendage-derived stem cells remains limited. In this review, we summarize the current knowledge of skin appendage-derived stem cells, including their fundamental characteristics, their preferentially expressed biomarkers, and their potential contribution involved in wound repair. Finally, we will also discuss current strategies, future applications, and limitations of these stem cells, attempting to provide some perspectives on optimizing the available therapy in cutaneous repair and regeneration.

  6. TRIM72 modulates caveolar endocytosis in repair of lung cells.

    Science.gov (United States)

    Nagre, Nagaraja; Wang, Shaohua; Kellett, Thomas; Kanagasabai, Ragu; Deng, Jing; Nishi, Miyuki; Shilo, Konstantin; Oeckler, Richard A; Yalowich, Jack C; Takeshima, Hiroshi; Christman, John; Hubmayr, Rolf D; Zhao, Xiaoli

    2016-03-01

    Alveolar epithelial and endothelial cell injury is a major feature of the acute respiratory distress syndrome, in particular when in conjunction with ventilation therapies. Previously we showed [Kim SC, Kellett T, Wang S, Nishi M, Nagre N, Zhou B, Flodby P, Shilo K, Ghadiali SN, Takeshima H, Hubmayr RD, Zhao X. Am J Physiol Lung Cell Mol Physiol 307: L449-L459, 2014.] that tripartite motif protein 72 (TRIM72) is essential for amending alveolar epithelial cell injury. Here, we posit that TRIM72 improves cellular integrity through its interaction with caveolin 1 (Cav1). Our data show that, in primary type I alveolar epithelial cells, lack of TRIM72 led to significant reduction of Cav1 at the plasma membrane, accompanied by marked attenuation of caveolar endocytosis. Meanwhile, lentivirus-mediated overexpression of TRIM72 selectively increases caveolar endocytosis in rat lung epithelial cells, suggesting a functional association between these two. Further coimmunoprecipitation assays show that deletion of either functional domain of TRIM72, i.e., RING, B-box, coiled-coil, or PRY-SPRY, abolishes the physical interaction between TRIM72 and Cav1, suggesting that all theoretical domains of TRIM72 are required to forge a strong interaction between these two molecules. Moreover, in vivo studies showed that injurious ventilation-induced lung cell death was significantly increased in knockout (KO) TRIM72(KO) and Cav1(KO) lungs compared with wild-type controls and was particularly pronounced in double KO mutants. Apoptosis was accompanied by accentuation of gross lung injury manifestations in the TRIM72(KO) and Cav1(KO) mice. Our data show that TRIM72 directly and indirectly modulates caveolar endocytosis, an essential process involved in repair of lung epithelial cells through removal of plasma membrane wounds. Given TRIM72's role in endomembrane trafficking and cell repair, we consider this molecule an attractive therapeutic target for patients with injured lungs.

  7. Human periodontal ligament stem cells repair mental nerve injury*

    Institute of Scientific and Technical Information of China (English)

    Bohan Li; Hun-Jong Jung; Soung-Min Kim; Myung-Jin Kim; Jeong Won Jahng; Jong-Ho Lee

    2013-01-01

    Human periodontal ligament stem cells are easily accessible and can differentiate into Schwann cells. We hypothesized that human periodontal ligament stem cells can be used as an alternative source for the autologous Schwann cells in promoting the regeneration of injured peripheral nerve. To validate this hypothesis, human periodontal ligament stem cells (1 × 106) were injected into the crush-injured left mental nerve in rats. Simultaneously, autologous Schwann cells (1 × 106) and PBS were also injected as controls. Real-time reverse transcriptase polymerase chain reaction showed that at 5 days after injection, mRNA expression of low affinity nerve growth factor receptor was sig-nificantaly increased in the left trigeminal ganglion of rats with mental nerve injury. Sensory tests, histomorphometric evaluation and retrograde labeling demonstrated that at 2 and 4 weeks after in-jection, sensory function was significantly improved, the numbers of retrograde labeled sensory neurons and myelinated axons were significantly increased, and human periodontal ligament stem cells and autologous Schwann cells exhibited similar therapeutic effects. These findings suggest that transplantation of human periodontal ligament stem cells show a potential value in repair of mental nerve injury.

  8. Stem cells and injectable hydrogels: Synergistic therapeutics in myocardial repair.

    Science.gov (United States)

    Sepantafar, Mohammadmajid; Maheronnaghsh, Reihan; Mohammadi, Hossein; Rajabi-Zeleti, Sareh; Annabi, Nasim; Aghdami, Nasser; Baharvand, Hossein

    2016-01-01

    One of the major problems in the treatment of cardiovascular diseases is the inability of myocardium to self-regenerate. Current therapies are unable to restore the heart's function after myocardial infarction. Myocardial tissue engineering is potentially a key approach to regenerate damaged heart muscle. Myocardial patches are applied surgically, whereas injectable hydrogels provide effective minimally invasive approaches to recover functional myocardium. These hydrogels are easily administered and can be either cell free or loaded with bioactive agents and/or cardiac stem cells, which may apply paracrine effects. The aim of this review is to investigate the advantages and disadvantages of injectable stem cell-laden hydrogels and highlight their potential applications for myocardium repair.

  9. A cell-free scaffold-based cartilage repair provides improved function hyaline-like repair at one year.

    Science.gov (United States)

    Siclari, Alberto; Mascaro, Gennaro; Gentili, Chiara; Cancedda, Ranieri; Boux, Eugenio

    2012-03-01

    Bone marrow stimulation techniques in cartilage repair such as drilling are limited by the formation of fibrous to hyaline-like repair tissue. It has been suggested such techniques can be enhanced by covering the defect with scaffolds. We present an innovative approach using a polyglycolic acid (PGA)-hyaluronan scaffold with platelet-rich-plasma (PRP) in drilling. We asked whether (1) PRP immersed in a cell-free PGA-hyaluronan scaffold improves patient-reported 1-year outcomes for the Knee injury and Osteoarthritis Score (KOOS), and (2) implantation of the scaffold in combination with bone marrow stimulation leads to the formation of hyaline-like cartilage repair tissue. We reviewed 52 patients who had arthroscopic implantation of the PGA-hyaluronan scaffold immersed with PRP in articular cartilage defects of the knee pretreated with Pridie drilling. Patients were assessed by KOOS. At 9 months followup, histologic staining was performed in specimens obtained from five patients to assess the repair tissue quality. The KOOS subscores improved for pain (55 to 91), symptoms (57 to 88), activities of daily living (69 to 86), sports and recreation (36 to 70), and quality of life (38 to 73). The histologic evaluation showed a homogeneous hyaline-like cartilage repair tissue. The cell-free PGA-hyaluronan scaffold combined with PRP leads to cartilage repair and improved patient-reported outcomes (KOOS) during 12 months of followup. Histologic sections showed morphologic features of hyaline-like repair tissue. Long-term followup is needed to determine if the cartilage repair tissue is durable. Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

  10. DNA repair by nonhomologous end joining and homologous recombination during cell cycle in human cells

    Science.gov (United States)

    Mao, Zhiyong; Bozzella, Michael; Seluanov, Andrei; Gorbunova, Vera

    2009-01-01

    DNA double-strand breaks (DSBs) are dangerous lesions that can lead to potentially oncogenic genomic rearrangements or cell death. The two major pathways for repair of DSBs are nonhomologous end joining (NHEJ) and homologous recombination (HR). NHEJ is an intrinsically error-prone pathway while HR results in accurate repair. To understand the origin of genomic instability in human cells it is important to know the contribution of each DSB repair pathway. Studies of rodent cells and human cancer cell lines have shown that the choice between NHEJ or HR pathways depends on cell cycle stage. Surprisingly, cell cycle regulation of DSB repair has not been examined in normal human cells with intact cell cycle checkpoints. Here we measured the efficiency of NHEJ and HR at different cell cycle stages in hTERT-immortalized diploid human fibroblasts. We utilized cells with chromosomally-integrated fluorescent reporter cassettes, in which a unique DSB is introduced by a rare-cutting endonuclease. We show that NHEJ is active throughout the cell cycle, and its activity increases as cells progress from G1 to G2/M (G1cell cycle stages. We conclude that human somatic cells utilize error-prone NHEJ as the major DSB repair pathway at all cell cycle stages, while HR is used, primarily, in the S phase. PMID:18769152

  11. Stem Cells for Temporomandibular Joint Repair and Regeneration.

    Science.gov (United States)

    Zhang, Shipin; Yap, Adrian U J; Toh, Wei Seong

    2015-10-01

    Temporomandibular Disorders (TMD) represent a heterogeneous group of musculoskeletal and neuromuscular conditions involving the temporomandibular joint (TMJ), masticatory muscles and/or associated structures. They are a major cause of non-dental orofacial pain. As a group, they are often multi-factorial in nature and have no common etiology or biological explanations. TMD can be broadly divided into masticatory muscle and TMJ disorders. TMJ disorders are characterized by intra-articular positional and/or structural abnormalities. The most common type of TMJ disorders involves displacement of the TMJ articular disc that precedes progressive degenerative changes of the joint leading to osteoarthritis (OA). In the past decade, progress made in the development of stem cell-based therapies and tissue engineering have provided alternative methods to attenuate the disease symptoms and even replace the diseased tissue in the treatment of TMJ disorders. Resident mesenchymal stem cells (MSCs) have been isolated from the synovia of TMJ, suggesting an important role in the repair and regeneration of TMJ. The seminal discovery of pluripotent stem cells including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have provided promising cell sources for drug discovery, transplantation as well as for tissue engineering of TMJ condylar cartilage and disc. This review discusses the most recent advances in development of stem cell-based treatments for TMJ disorders through innovative approaches of cell-based therapeutics, tissue engineering and drug discovery.

  12. Advances of stem cell based-therapeutic approaches for tendon repair

    Directory of Open Access Journals (Sweden)

    Lidi Liu

    2017-04-01

    The translational potential of this article: This paper reviews recent progress on stem cell-based therapeutic approaches for tendon repair, which highlights its translational potential and challenges.

  13. Repair at single targeted DNA double-strand breaks in pluripotent and differentiated human cells.

    Directory of Open Access Journals (Sweden)

    Hua Fung

    Full Text Available Differences in ex vivo cell culture conditions can drastically affect stem cell physiology. We sought to establish an assay for measuring the effects of chemical, environmental, and genetic manipulations on the precision of repair at a single DNA double-strand break (DSB in pluripotent and somatic human cells. DSBs in mammalian cells are primarily repaired by either homologous recombination (HR or nonhomologous end-joining (NHEJ. For the most part, previous studies of DSB repair in human cells have utilized nonspecific clastogens like ionizing radiation, which are highly nonphysiologic, or assayed repair at randomly integrated reporters. Measuring repair after random integration is potentially confounded by locus-specific effects on the efficiency and precision of repair. We show that the frequency of HR at a single DSB differs up to 20-fold between otherwise isogenic human embryonic stem cells (hESCs based on the site of the DSB within the genome. To overcome locus-specific effects on DSB repair, we used zinc finger nucleases to efficiently target a DSB repair reporter to a safe-harbor locus in hESCs and a panel of somatic human cell lines. We demonstrate that repair at a targeted DSB is highly precise in hESCs, compared to either the somatic human cells or murine embryonic stem cells. Differentiation of hESCs harboring the targeted reporter into astrocytes reduces both the efficiency and precision of repair. Thus, the phenotype of repair at a single DSB can differ based on either the site of damage within the genome or the stage of cellular differentiation. Our approach to single DSB analysis has broad utility for defining the effects of genetic and environmental modifications on repair precision in pluripotent cells and their differentiated progeny.

  14. Plasma membrane repair: the adaptable cell life-insurance.

    Science.gov (United States)

    Jimenez, Ana Joaquina; Perez, Franck

    2017-08-01

    The plasma membrane is the most basic element necessary for the cell to exist and be distinguishable from its environment. Regulated mechanisms allow tightly controlled communication between intacellular and extracellular medium allowing the maintenance of a specific biochemical environment, optimized for cellular functions. The anarchic and uncontrolled opening of a hole in the PM induces a change in the concentration of ions and oxidizing agents perturbing homeostasis. Fortunately, the cell possesses mechanisms that are capable of reacting to sudden extracellular medium entry and to block the leakage locally. Here we summarize the known mechanisms of membrane repair and how the size of the wound and the resulting calcium entry activates preferentially one or another mechanism adapted to the magnitude of the injury. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Potential of cardiac stem/progenitor cells and induced pluripotent stem cells for cardiac repair in ischaemic heart disease

    OpenAIRE

    Wang, Wei Eric; Chen, Xiongwen; Houser, Steven R.; Zeng, Chunyu

    2013-01-01

    Stem cell therapy has emerged as a promising strategy for cardiac and vascular repair. The ultimate goal is to rebuild functional myocardium by transplanting exogenous stem cells or by activating native stem cells to induce endogenous repair. CS/PCs (cardiac stem/progenitor cells) are one type of adult stem cell with the potential to differentiate into cardiac lineages (cardiomyocytes, smooth muscle cells and endothelial cells). iPSCs (induced pluripotent stem cells) also ha...

  16. Progenitor Cells for Arterial Repair: Incremental Advancements towards Therapeutic Reality

    Science.gov (United States)

    Simard, Trevor; Jung, Richard G.; Motazedian, Pouya; Di Santo, Pietro; Ramirez, F. Daniel; Russo, Juan J.; Labinaz, Alisha; Yousef, Altayyeb; Anantharam, Brijesh; Pourdjabbar, Ali

    2017-01-01

    Coronary revascularization remains the standard treatment for obstructive coronary artery disease and can be accomplished by either percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery. Considerable advances have rendered PCI the most common form of revascularization and improved clinical outcomes. However, numerous challenges to modern PCI remain, namely, in-stent restenosis and stent thrombosis, underscoring the importance of understanding the vessel wall response to injury to identify targets for intervention. Among recent promising discoveries, endothelial progenitor cells (EPCs) have garnered considerable interest given an increasing appreciation of their role in vascular homeostasis and their ability to promote vascular repair after stent placement. Circulating EPC numbers have been inversely correlated with cardiovascular risk, while administration of EPCs in humans has demonstrated improved clinical outcomes. Despite these encouraging results, however, advancing EPCs as a therapeutic modality has been hampered by a fundamental roadblock: what constitutes an EPC? We review current definitions and sources of EPCs as well as the proposed mechanisms of EPC-mediated vascular repair. Additionally, we discuss the current state of EPCs as therapeutic agents, focusing on endogenous augmentation and transplantation. PMID:28232850

  17. Repair of DNA damage induced by anthanthrene, a polycyclic aromatic hydrocarbon (PAH) without bay or fjord regions

    DEFF Research Database (Denmark)

    Madsen, Claus Desler; Johannessen, Christian; Rasmussen, Lene Juel

    2009-01-01

    Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants, formed during incomplete burning of coal, oil and gas. Several PAHs have carcinogenic and mutagenic potencies, but these compounds must be activated in order to exert their mutagenic effects. One of the principal pathways...

  18. DNA repair in human cells: from genetic complementation to isolation of genes.

    NARCIS (Netherlands)

    D. Bootsma (Dirk); A. Westerveld (Andries); J.H.J. Hoeijmakers (Jan)

    1988-01-01

    textabstractThe genetic disease xeroderma pigmentosum (XP) demonstrates the association between defective repair of DNA lesions and cancer. Complementation analysis performed on XP cell strains and on repair deficient rodent cell lines has revealed that at least nine and possibly more than 13 genes

  19. DNA repair in human cells: from genetic complementation to isolation of genes.

    NARCIS (Netherlands)

    D. Bootsma (Dirk); A. Westerveld (Andries); J.H.J. Hoeijmakers (Jan)

    1988-01-01

    textabstractThe genetic disease xeroderma pigmentosum (XP) demonstrates the association between defective repair of DNA lesions and cancer. Complementation analysis performed on XP cell strains and on repair deficient rodent cell lines has revealed that at least nine and possibly more than 13 genes

  20. Satellite Cells Contribution to Exercise Mediated Muscle Hypertrophy and Repair

    Science.gov (United States)

    Bazgir, Behzad; Fathi, Rouhollah; Rezazadeh Valojerdi, Mojtaba; Mozdziak, Paul; Asgari, Alireza

    2017-01-01

    Satellite cells (SCs) are the most abundant skeletal muscle stem cells. They are widely recognized for their contributions to maintenance of muscle mass, regeneration and hypertrophy during the human life span. These cells are good candidates for cell therapy due to their self-renewal capabilities and presence in an undifferentiated form. Presently, a significant gap exists between our knowledge of SCs behavior and their application as a means for human skeletal muscle tissue repair and regeneration. Both physiological and pathological stimuli potentially affect SCs activation, proliferation, and terminal differentiation the former category being the focus of this article. Activation of SCs occurs following exercise, post-training micro-injuries, and electrical stimulation. Exercise, as a potent and natural stimulus, is at the center of numerous studies on SC activation and relevant fields. According to research, different exercise modalities end with various effects. This review article attempts to picture the state of the art of the SCs life span and their engagement in muscle regeneration and hypertrophy in exercise. PMID:28042532

  1. Satellite Cells Contribution to Exercise Mediated Muscle Hypertrophy and Repair

    Directory of Open Access Journals (Sweden)

    Behzad Bazgir

    2016-10-01

    Full Text Available Satellite cells (SCs are the most abundant skeletal muscle stem cells. They are widely recognized for their contributions to maintenance of muscle mass, regeneration and hypertrophy during the human life span. These cells are good candidates for cell therapy due to their self-renewal capabilities and presence in an undifferentiated form. Presently, a significant gap exists between our knowledge of SCs behavior and their application as a means for human skeletal muscle tissue repair and regeneration. Both physiological and pathological stimuli potentially affect SCs activation, proliferation, and terminal differentiation - the former category being the focus of this article. Activation of SCs occurs following exercise, post-training micro-injuries, and electrical stimulation. Exercise, as a potent and natural stimulus, is at the center of numerous studies on SC activation and relevant fields. According to research, different exercise modalities end with various effects. This review article attempts to picture the state of the art of the SCs life span and their engagement in muscle regeneration and hypertrophy in exercise.

  2. Microplasma reforming of hydrocarbons for fuel cell power

    Science.gov (United States)

    Besser, R. S.; Lindner, P. J.

    The implementation of a microplasma approach for small scale reforming processes is explored as an alternative to more standard catalyst-based processes. Plasmas are a known approach to activating a chemical reaction in place of catalysts, and microplasmas are particularly attractive owing to their extremely high electron and power densities. Their inherent compactness gives them appeal for portable applications, but their modularity leads to scalability for higher capacity. We describe the realization of experimental microplasma reactors based on the microhollow cathode discharge (MHCD) structure by silicon micromachining for device fabrication. Experiments were carried out with model hydrocarbons methane and butane in the reactors within a microfluidic flow and analytical setup. We observe several key phenomena, including the ability to liberate hydrogen from the hydrocarbons at temperatures near ambient and sub-Watt input power levels, the tendency toward hydrocarbon decomposition rather than oxidation even in the presence of oxygen, and the need for a neutral carrier to obtain conversion. Mass and energy balances on these experiments revealed conversions up to nearly 50%, but the conversion of electrical power input to chemical reaction enthalpy was only on the order of 1%. These initial, exploratory results were recorded with devices and at process settings without optimization, and are hence promising for an emerging, catalyst-free reforming approach.

  3. DNA Repair in Human Pluripotent Stem Cells Is Distinct from That in Non-Pluripotent Human Cells

    Science.gov (United States)

    Luo, Li Z.; Park, Sang-Won; Bates, Steven E.; Zeng, Xianmin; Iverson, Linda E.; O'Connor, Timothy R.

    2012-01-01

    The potential for human disease treatment using human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells (iPSCs), also carries the risk of added genomic instability. Genomic instability is most often linked to DNA repair deficiencies, which indicates that screening/characterization of possible repair deficiencies in pluripotent human stem cells should be a necessary step prior to their clinical and research use. In this study, a comparison of DNA repair pathways in pluripotent cells, as compared to those in non-pluripotent cells, demonstrated that DNA repair capacities of pluripotent cell lines were more heterogeneous than those of differentiated lines examined and were generally greater. Although pluripotent cells had high DNA repair capacities for nucleotide excision repair, we show that ultraviolet radiation at low fluxes induced an apoptotic response in these cells, while differentiated cells lacked response to this stimulus, and note that pluripotent cells had a similar apoptotic response to alkylating agent damage. This sensitivity of pluripotent cells to damage is notable since viable pluripotent cells exhibit less ultraviolet light-induced DNA damage than do differentiated cells that receive the same flux. In addition, the importance of screening pluripotent cells for DNA repair defects was highlighted by an iPSC line that demonstrated a normal spectral karyotype, but showed both microsatellite instability and reduced DNA repair capacities in three out of four DNA repair pathways examined. Together, these results demonstrate a need to evaluate DNA repair capacities in pluripotent cell lines, in order to characterize their genomic stability, prior to their pre-clinical and clinical use. PMID:22412831

  4. Flow cytometry detection of planktonic cells with polycyclic aromatic hydrocarbons sorbed to cell surfaces

    KAUST Repository

    Cerezo, Maria I.

    2017-02-17

    Polycyclic aromatic hydrocarbons are very important components of oil pollution. These pollutants tend to sorb to cell surfaces, exerting toxic effects on organisms. Our study developed a flow cytometric method for the detection of PAHs sorbed to phytoplankton by exploiting their spectral characteristics. We discriminated between cells with PAHs from cells free of PAHs. Clear discrimination was observed with flow cytometer provided with 375 or 405nm lasers in addition to the standard 488nm laser necessary to identify phytoplankton. Using this method, we measured the relationship between the percentages of phytoplankton organisms with PAHs, with the decrease in the growth rate. Moreover, the development of this method could be extended to facilitate the study of PAHs impact on cell cultures from a large variety of organisms.

  5. MICROBIAL CELL-SURFACE HYDROPHOBICITY - THE INVOLVEMENT OF ELECTROSTATIC INTERACTIONS IN MICROBIAL ADHESION TO HYDROCARBONS (MATH)

    NARCIS (Netherlands)

    GEERTSEMADOORNBUSCH, GI; VANDERMEI, HC; BUSSCHER, HJ

    Microbial adhesion to hydrocarbons (MATH) is the most commonly used method to determine microbial cell surface hydrophobicity. Since, however, the assay is based on adhesion, it is questionable whether the results reflect only the cell surface hydrophobicity or an interplay of hydrophobicity and

  6. Stem cells for cardiac repair: problems and possibilities.

    Science.gov (United States)

    Henning, Robert J

    2013-11-01

    Ischemic heart disease is a major cause of death throughout the world. In order to limit myocardial damage and possibly generate new myocardium, stem cells are currently being injected into patients with ischemic heart disease. Three major patient investigations, The LateTIME, the TIME and the Swiss Myocardial Infarction trials, have recently addressed the questions of whether progenitor cells from unfractionated bone marrow mononuclear cells limit myocardial damage and what the optimal time to inject these cells after acute myocardial infarctions (AMIs) is. In each of these trials, there were no significant differences between treated and control patients when bone marrow cells were administered 5-7 days or 2-3 weeks after AMIs. Nevertheless, these investigations provide important information regarding clinical trial designs. Patients with AMIs in these trials were treated with percutaneous coronary intervention within a median of 4-5 h after the onset of chest pain. Thereafter, all patients received guideline-guided optimal medical therapy. Consequently, the sizes of AMIs were significantly limited. In patients with small AMIs and near-normal left ventricular ejection fractions, progenitor cells are least effective. However, these trials do question whether autologous bone marrow mononuclear cells are the optimal cells for myocardial repair owing to low numbers of progenitor cells in bone marrow aspirates and the significant variability in potency and efficacy of these cells in patients with chronic multisystem diseases. In contrast, the SCIPIO and the CAUDUCEUS trials examined cardiac progenitor cells in patients with ischemic cardiomyopathies. These trials reported over 1-2 years that cardiac progenitor cells produced significant improvements in left ventricular contractility due to 12-24 g decreases in myocardial scars and 18-23 g increases in viable myocardial muscle. However, caution must be exercised in the interpretation of these studies due to the small

  7. Myosin II does not contribute to wound repair in Dictyostelium cells

    Directory of Open Access Journals (Sweden)

    Shigehiko Yumura

    2014-09-01

    Full Text Available Cells are always subjected to mechanical stresses, resulting in wounds of the cell membrane, but cells are able to repair and reseal their wounded membrane. Previous reports have shown that actin and myosin II accumulate around the wound and that the constriction of this purse-string closes the membrane pore. Here, we developed a microsurgical wound assay to assess wound repair in Dictyostelium cells. Fluorescent dye that had been incorporated into the cells leaked out for only 2–3 sec after wounding, and a GFP-derived, fluorescent Ca2+ sensor showed that intracellular Ca2+ transiently increased immediately after wounding. In the absence of external Ca2+, the cell failed to repair itself. During the repair process, actin accumulated at the wounded sites but myosin II did not. The wounds were repaired even in myosin II null cells to a comparable degree as the wild-type cells, suggesting that myosin II does not contribute to wound repair. Thus, the actomyosin purse-string constriction model is not a common mechanism for wound repair in eukaryotic cells, and this discrepancy may arise from the difference in cell size.

  8. Stem/progenitor cells: a potential source of retina-specific cells for retinal repair.

    Science.gov (United States)

    Bi, Yong-Yan; Feng, Dong-Fu; Pan, Dong-Chao

    2009-11-01

    Retinal injury generally results in permanent visual disturbance or even blindness. Any effort to restore vision in such condition would require replacement of the highly specialized retinal cells. Stem/progenitor cells have been proposed as a potential source of new retina-specific cells to replace those lost due to retina injury. Evidence to date suggests that continued development of stem cell therapies may ultimately lead to viable treatment options for retina injury. A wide range of stem/progenitor cells from various sources is currently being investigated for the treatment of retinal injury. This article reviews the recent achievements about stem/progenitor cell source for retinal repair.

  9. Polymeric scaffolds as stem cell carriers in bone repair.

    Science.gov (United States)

    Rossi, Filippo; Santoro, Marco; Perale, Giuseppe

    2015-10-01

    Although bone has a high potential to regenerate itself after damage and injury, the efficacious repair of large bone defects resulting from resection, trauma or non-union fractures still requires the implantation of bone grafts. Materials science, in conjunction with biotechnology, can satisfy these needs by developing artificial bones, synthetic substitutes and organ implants. In particular, recent advances in polymer science have provided several innovations, underlying the increasing importance of macromolecules in this field. To address the increasing need for improved bone substitutes, tissue engineering seeks to create synthetic, three-dimensional scaffolds made from polymeric materials, incorporating stem cells and growth factors, to induce new bone tissue formation. Polymeric materials have shown a great affinity for cell transplantation and differentiation and, moreover, their structure can be tuned in order to maintain an adequate mechanical resistance and contemporarily be fully bioresorbable. This review emphasizes recent progress in polymer science that allows relaible polymeric scaffolds to be synthesized for stem cell growth in bone regeneration.

  10. OPERATION OF SOLID OXIDE FUEL CELL ANODES WITH PRACTICAL HYDROCARBON FUELS

    Energy Technology Data Exchange (ETDEWEB)

    Scott A. Barnett; Jiang Liu; Yuanbo Lin

    2004-07-30

    This work was carried out to achieve a better understanding of how SOFC anodes work with real fuels. The motivation was to improve the fuel flexibility of SOFC anodes, thereby allowing simplification and cost reduction of SOFC power plants. The work was based on prior results indicating that Ni-YSZ anode-supported SOFCs can be operated directly on methane and natural gas, while SOFCs with novel anode compositions can work with higher hydrocarbons. While these results were promising, more work was clearly needed to establish the feasibility of these direct-hydrocarbon SOFCs. Basic information on hydrocarbon-anode reactions should be broadly useful because reformate fuel gas can contain residual hydrocarbons, especially methane. In the Phase I project, we have studied the reaction mechanisms of various hydrocarbons--including methane, natural gas, and higher hydrocarbons--on two kinds of Ni-containing anodes: conventional Ni-YSZ anodes and a novel ceramic-based anode composition that avoid problems with coking. The effect of sulfur impurities was also studied. The program was aimed both at achieving an understanding of the interactions between real fuels and SOFC anodes, and providing enough information to establish the feasibility of operating SOFC stacks directly on hydrocarbon fuels. A combination of techniques was used to provide insight into the hydrocarbon reactions at these anodes during SOFC operation. Differentially-pumped mass spectrometry was be used for product-gas analysis both with and without cell operation. Impedance spectroscopy was used in order to understand electrochemical rate-limiting steps. Open-circuit voltages measurements under a range of conditions was used to help determine anode electrochemical reactions. Life tests over a wide range of conditions were used to establish the conditions for stable operation of anode-supported SOFC stacks directly on methane. Redox cycling was carried out on ceramic-based anodes. Tests on sulfur tolerance of

  11. Cell resistance to the Cytolethal Distending Toxin involves an association of DNA repair mechanisms

    Science.gov (United States)

    Bezine, Elisabeth; Malaisé, Yann; Loeuillet, Aurore; Chevalier, Marianne; Boutet-Robinet, Elisa; Salles, Bernard; Mirey, Gladys; Vignard, Julien

    2016-01-01

    The Cytolethal Distending Toxin (CDT), produced by many bacteria, has been associated with various diseases including cancer. CDT induces DNA double-strand breaks (DSBs), leading to cell death or mutagenesis if misrepaired. At low doses of CDT, other DNA lesions precede replication-dependent DSB formation, implying that non-DSB repair mechanisms may contribute to CDT cell resistance. To address this question, we developed a proliferation assay using human cell lines specifically depleted in each of the main DNA repair pathways. Here, we validate the involvement of the two major DSB repair mechanisms, Homologous Recombination and Non Homologous End Joining, in the management of CDT-induced lesions. We show that impairment of single-strand break repair (SSBR), but not nucleotide excision repair, sensitizes cells to CDT, and we explore the interplay of SSBR with the DSB repair mechanisms. Finally, we document the role of the replicative stress response and demonstrate the involvement of the Fanconi Anemia repair pathway in response to CDT. In conclusion, our work indicates that cellular survival to CDT-induced DNA damage involves different repair pathways, in particular SSBR. This reinforces a model where CDT-related genotoxicity primarily involves SSBs rather than DSBs, underlining the importance of cell proliferation during CDT intoxication and pathogenicity. PMID:27775089

  12. Macrophages: supportive cells for tissue repair and regeneration.

    Science.gov (United States)

    Chazaud, Bénédicte

    2014-03-01

    Macrophages, and more broadly inflammation, have been considered for a long time as bad markers of tissue homeostasis. However, if it is indisputable that macrophages are associated with many diseases in a deleterious way, new roles have emerged, showing beneficial properties of macrophages during tissue repair and regeneration. This discrepancy is likely due to the high plasticity of macrophages, which may exhibit a wide range of phenotypes and functions depending on their environment. Therefore, regardless of their role in immunity, macrophages play a myriad of roles in the maintenance and recovery of tissue homeostasis. They take a major part in the resolution of inflammation. They also exert various effects of parenchymal cells, including stem and progenitor cell, of which they regulate the fate. In the present review, few examples from various tissues are presented to illustrate that, beyond their specific properties in a given tissue, common features have been described that sustain a role of macrophages in the recovery and maintenance of tissue homeostasis.

  13. Electrode Design for Low Temperature Direct-Hydrocarbon Solid Oxide Fuel Cells

    Science.gov (United States)

    Chen, Fanglin (Inventor); Zhao, Fei (Inventor); Liu, Qiang (Inventor)

    2015-01-01

    In certain embodiments of the present disclosure, a solid oxide fuel cell is described. The solid oxide fuel cell includes a hierarchically porous cathode support having an impregnated cobaltite cathode deposited thereon, an electrolyte, and an anode support. The anode support includes hydrocarbon oxidation catalyst deposited thereon, wherein the cathode support, electrolyte, and anode support are joined together and wherein the solid oxide fuel cell operates a temperature of 600.degree. C. or less.

  14. Studies on bleomycin-induced repair DNA synthesis in permeable mouse ascites sarcoma cells.

    Directory of Open Access Journals (Sweden)

    Mori,Shigeru

    1989-04-01

    Full Text Available To study the mechanism of DNA excision repair, a DNA repair system employing permeable mouse sarcoma (SR-C3H/He cells was established and characterized. SR-C3H/He cells were permeabilized with a 0.0175% Triton X-100 solution. The permeable cells were treated with 1 mM ATP and 0.11 mM bleomycin, and then washed thoroughly to remove ATP and bleomycin. Repair DNA synthesis occurred in the bleomycin-damaged, permeable SR-C3H/He cells when incubated with ATP and four deoxyribonucleoside triphosphates. The repair nature of the DNA synthesis was confirmed by the BrdUMP density shift technique, and by the reduced sensitivity of the newly synthesized DNA to Escherichia coli exonuclease III. The DNA synthesis was optimally enhanced by addition of 0.08 M NaCl. Studies using selective inhibitors of DNA synthesis showed that aphidicolin-sensitive DNA polymerase (DNA polymerase alpha and/or delta and DNA polymerase beta were involved in the repair process. The present DNA repair system is thought to be useful to study nuclear DNA damage by bleomycin, removal of the damaged ends by an exonuclease, repair DNA synthesis by DNA polymerases and repair patch ligation by DNA ligase(s.

  15. The indirect effect of radiation reduces the repair fidelity of NHEJ as verified in repair deficient CHO cell lines exposed to different radiation qualities and potassium bromate

    Energy Technology Data Exchange (ETDEWEB)

    Bajinskis, Ainars, E-mail: ainars.bajinskis@gmt.su.se [Centre for Radiation Protection Research, Department of Genetics, Microbiology and Toxicology, Stockholm University, S-10691 Stockholm (Sweden); Olsson, Gunilla; Harms-Ringdahl, Mats [Centre for Radiation Protection Research, Department of Genetics, Microbiology and Toxicology, Stockholm University, S-10691 Stockholm (Sweden)

    2012-03-01

    The complexity of DNA lesions induced by ionizing radiation is mainly dependent on radiation quality, where the indirect action of radiation may contribute to different extent depending on the type of radiation under study. The effect of indirect action of radiation can be investigated by using agents that induce oxidative DNA damage or by applying free radical scavengers. The aim of this study was to investigate the role of the indirect effect of radiation for the repair fidelity of non-homologous end-joining (NHEJ), homologous recombination repair (HRR) and base excision repair (BER) when DNA damage of different complexity was induced by gamma radiation, alpha particles or from base damages (8-oxo-dG) induced by potassium bromate (KBrO{sub 3}). CHO cells lines deficient in XRCC3 (HRR) irs1SF, XRCC7 (NHEJ) V3-3 and XRCC1 (BER) EM9 were irradiated in the absence or presence of the free radical scavenger dimethyl sulfoxide (DMSO). The endpoints investigated included rate of cell proliferation by the DRAG assay, clonogenic cell survival and the level of primary DNA damage by the comet assay. The results revealed that the indirect effect of low-LET radiation significantly reduced the repair fidelity of both NHEJ and HRR pathways. For high-LET radiation the indirect effect of radiation also significantly reduced the repair fidelity for the repair deficient cell lines. The results suggest further that the repair fidelity of the error prone NHEJ repair pathway is more impaired by the indirect effect of high-LET radiation relative to the other repair pathways studied. The response to bromate observed for the two DSB repair deficient cell lines strongly support earlier studies that bromate induces complex DNA damages. The significantly reduced repair fidelity of irs1SF and V3-3 suggests that NHEJ as well as HRR are needed for the repair, and that complex DSBs are formed after bromate exposure.

  16. Aryl hydrocarbon receptor ligand effects in RBL2H3 cells

    DEFF Research Database (Denmark)

    Maaetoft-Udsen, Kristina; Shimoda, Lori M. N.; Frøkiær, Hanne;

    2012-01-01

    The aryl hydrocarbon receptor (AHR) mediates toxic effects of dioxin and xenobiotic metabolism. AHR has an emerging role in the immune system, but its physiological ligands and functional role in immunocytes remain poorly understood. Mast cells are immunocytes that are central to inflammatory...

  17. The aryl hydrocarbon receptor:a regulator of Th17 and Treg cell development in disease

    Institute of Scientific and Technical Information of China (English)

    Peggy P Ho; Lawrence Steinman

    2008-01-01

    @@ The aryl hydrocarbon receptor (AhR)was discovered almost 30 years ago as a specific binding site for the halogenated polycyclic aromatic hydrocarbon,2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD),an environmental toxin (as reviewed in [1]).Within the last decade,AhR was found to have a basic helixloop-helix and function as a ligand-activated transcription factor.Located in the cytoplasm of most cells,AhR forms a receptor complex with several proteins including the chaperone protein hsp90 (a 90kDa heat shock protein).

  18. Horizontal arrangement of anodes of microbial fuel cells enhances remediation of petroleum hydrocarbon-contaminated soil.

    Science.gov (United States)

    Zhang, Yueyong; Wang, Xin; Li, Xiaojing; Cheng, Lijuan; Wan, Lili; Zhou, Qixing

    2015-02-01

    With the aim of in situ bioremediation of soil contaminated by hydrocarbons, anodes arranged with two different ways (horizontal or vertical) were compared in microbial fuel cells (MFCs). Charge outputs as high as 833 and 762C were achieved in reactors with anodes horizontally arranged (HA) and vertically arranged (VA). Up to 12.5 % of the total petroleum hydrocarbon (TPH) was removed in HA after 135 days, which was 50.6 % higher than that in VA (8.3 %) and 95.3 % higher than that in the disconnected control (6.4 %). Hydrocarbon fingerprint analysis showed that the degradation rates of both alkanes and polycyclic aromatic hydrocarbons (PAHs) in HA were higher than those in VA. Lower mass transport resistance in the HA than that of the VA seems to result in more power and more TPH degradation. Soil pH was increased from 8.26 to 9.12 in HA and from 8.26 to 8.64 in VA, whereas the conductivity was decreased from 1.99 to 1.54 mS/cm in HA and from 1.99 to 1.46 mS/cm in VA accompanied with the removal of TPH. Considering both enhanced biodegradation of hydrocarbon and generation of charge in HA, the MFC with anodes horizontally arranged is a promising configuration for future applications.

  19. Integration of direct carbon and hydrogen fuel cells for highly efficient power generation from hydrocarbon fuels

    Energy Technology Data Exchange (ETDEWEB)

    Muradov, Nazim; Choi, Pyoungho; Smith, Franklyn; Bokerman, Gary [Florida Solar Energy Center, University of Central Florida, 1679 Clearlake Road, Cocoa, FL 32922-5703 (United States)

    2010-02-15

    In view of impending depletion of hydrocarbon fuel resources and their negative environmental impact, it is imperative to significantly increase the energy conversion efficiency of hydrocarbon-based power generation systems. The combination of a hydrocarbon decomposition reactor with a direct carbon and hydrogen fuel cells (FC) as a means for a significant increase in chemical-to-electrical energy conversion efficiency is discussed in this paper. The data on development and operation of a thermocatalytic hydrocarbon decomposition reactor and its coupling with a proton exchange membrane FC are presented. The analysis of the integrated power generating system including a hydrocarbon decomposition reactor, direct carbon and hydrogen FC using natural gas and propane as fuels is conducted. It was estimated that overall chemical-to-electrical energy conversion efficiency of the integrated system varied in the range of 49.4-82.5%, depending on the type of fuel and FC used, and CO{sub 2} emission per kW{sub el}h produced is less than half of that from conventional power generation sources. (author)

  20. DSB (Im)mobility and DNA repair compartmentalization in mammalian cells.

    Science.gov (United States)

    Lemaître, Charlène; Soutoglou, Evi

    2015-02-13

    Chromosomal translocations are considered as causal in approximately 20% of cancers. Therefore, understanding their mechanisms of formation is crucial in the prevention of carcinogenesis. The first step of translocation formation is the concomitant occurrence of double-strand DNA breaks (DSBs) in two different chromosomes. DSBs can be repaired by different repair mechanisms, including error-free homologous recombination (HR), potentially error-prone non-homologous end joining (NHEJ) and the highly mutagenic alternative end joining (alt-EJ) pathways. Regulation of DNA repair pathway choice is crucial to avoid genomic instability. In yeast, DSBs are mobile and can scan the entire nucleus to be repaired in specialized DNA repair centers or if they are persistent, in order to associate with the nuclear pores or the nuclear envelope where they can be repaired by specialized repair pathways. DSB mobility is limited in mammals; therefore, raising the question of whether the position at which a DSB occurs influences its repair. Here, we review the recent literature addressing this question. We first present the reports describing the extent of DSB mobility in mammalian cells. In a second part, we discuss the consequences of non-random gene positioning on chromosomal translocations formation. In the third part, we discuss the mobility of heterochromatic DSBs in light of our recent data on DSB repair at the nuclear lamina, and finally, we show that DSB repair compartmentalization at the nuclear periphery is conserved from yeast to mammals, further pointing to a role for gene positioning in the outcome of DSB repair. When regarded as a whole, the different studies reviewed here demonstrate the importance of nuclear architecture on DSB repair and reveal gene positioning as an important parameter in the study of tumorigenesis.

  1. Complement activation in the context of stem cells and tissue repair

    Institute of Scientific and Technical Information of China (English)

    Ingrid; U; Schraufstatter; Sophia; K; Khaldoyanidi; Richard; G; DiScipio

    2015-01-01

    The complement pathway is best known for its role in immune surveillance and inflammation. However,its ability of opsonizing and removing not only pathogens,but also necrotic and apoptotic cells,is a phylogenetically ancient means of initiating tissue repair. The means and mechanisms of complement-mediated tissue repair are discussed in this review. There is increasing evidence that complement activation contributes to tissue repair at several levels. These range from the chemo-attraction of stem and progenitor cells to areas of complement activation,to increased survival of various cell types in the presence of split products of complement,and to the production of trophic factors by cells activated by the anaphylatoxins C3 a and C5 a. This repair aspect of complement biology has not found sufficient appreciation until recently. The following will examine this aspect of complement biology with an emphasis on the anaphylatoxins C3 a and C5 a.

  2. ATM prevents DSB formation by coordinating SSB repair and cell cycle progression.

    Science.gov (United States)

    Khoronenkova, Svetlana V; Dianov, Grigory L

    2015-03-31

    DNA single-strand breaks (SSBs) arise as a consequence of spontaneous DNA instability and are also formed as DNA repair intermediates. Their repair is critical because they otherwise terminate gene transcription and generate toxic DNA double-strand breaks (DSBs) on replication. To prevent the formation of DSBs, SSB repair must be completed before DNA replication. To accomplish this, cells should be able to detect unrepaired SSBs, and then delay cell cycle progression to allow more time for repair; however, to date there is no evidence supporting the coordination of SSB repair and replication in human cells. Here we report that ataxia-telangiectasia mutated kinase (ATM) plays a major role in restricting the replication of SSB-containing DNA and thus prevents DSB formation. We show that ATM is activated by SSBs and coordinates their repair with DNA replication. SSB-mediated ATM activation is followed by a G1 cell cycle delay that allows more time for repair and thus prevents the replication of damaged DNA and DSB accrual. These findings establish an unanticipated role for ATM in the signaling of DNA SSBs and provide important insight into the molecular defects leading to genetic instability in patients with ataxia-telangiectasia.

  3. Recent progress with the DNA repair mutants of Chinese hamster ovary cells

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, L.H.; Salazar, E.P.; Brookman, K.W.; Collins, C.C.; Stewart, S.A.; Busch, D.B.; Weber, C.A.

    1986-04-02

    Repair deficient mutants of Chinese hamster ovary (CHO) cells are being used to identify human genes that correct the repair defects and to study mechanisms of DNA repair and mutagenesis. Five independent tertiary DNA transformants were obtained from the EM9 mutant. In these clones a human DNA sequence was identified that correlated with the resistance of the cells to CldUrd. After Eco RI digestion, Southern transfer, and hybridization of transformant DNAs with the BLUR-8 Alu family sequence, a common fragment of 25 to 30 kb was present. 37 refs., 4 figs., 3 tabs.

  4. Age and gender effects on DNA strand break repair in peripheral blood mononuclear cells

    DEFF Research Database (Denmark)

    Garm, Christian; Moreno-Villanueva, Maria; Bürkle, Alexander;

    2013-01-01

    single-strand breaks (SSBs) and double-strand breaks (DSBs) in human peripheral blood mononuclear cells (PBMCs). Of these lesions, DSBs are the least frequent but the most dangerous for cells. We have measured the level of endogenous SSBs, SSB repair capacity, γ-H2AX response, and DSB repair capacity...... in a study population consisting of 216 individuals from a population-based sample of twins aged 40-77 years. Age in this range did not seem to have any effect on the SSB parameters. However, γ-H2AX response and DSB repair capacity decreased with increasing age, although the associations did not reach...

  5. Modeling the induced mutation process in bacterial cells with defects in excision repair system

    Science.gov (United States)

    Bugay, A. N.; Vasilyeva, M. A.; Krasavin, E. A.; Parkhomenko, A. Yu.

    2015-12-01

    A mathematical model of the UV-induced mutation process in Escherichia coli cells with defects in the uvrA and polA genes has been developed. The model describes in detail the reaction kinetics for the excision repair system. The number of mismatches as a result of translesion synthesis is calculated for both wild-type and mutant cells. The effect of temporal modulation of the number of single-stranded DNA during postreplication repair has been predicted. A comparison of effectiveness of different repair systems has been conducted.

  6. Formaldehyde catabolism is essential in cells deficient for the Fanconi anemia DNA-repair pathway.

    Science.gov (United States)

    Rosado, Ivan V; Langevin, Frédéric; Crossan, Gerry P; Takata, Minoru; Patel, Ketan J

    2011-11-13

    Metabolism is predicted to generate formaldehyde, a toxic, simple, reactive aldehyde that can damage DNA. Here we report a synthetic lethal interaction in avian cells between ADH5, encoding the main formaldehyde-detoxifying enzyme, and the Fanconi anemia (FA) DNA-repair pathway. These results define a fundamental role for the combined action of formaldehyde catabolism and DNA cross-link repair in vertebrate cell survival.

  7. Facile Synthesis of Highly Active and Robust Ni-Mo Bimetallic Electrocatalyst for Hydrocarbon Oxidation in Solid Oxide Fuel Cells

    NARCIS (Netherlands)

    Hua, B.; Li, M.; Zhang, Y.-Q.; Chen, J.; Sun, Y.-F.; Yan, N.; Li, J.; Luo, J.L.

    2016-01-01

    We report a novel Ni–Mo bimetallic alloy decorated with multimicrocrystals as an efficient anode catalyst for hydrocarbon-fueled solid oxide fuel cells (SOFCs). We show that these Ni–Mo bimetallic alloys are highly active, thermally stable, and sulfur/coke tolerant electrocatalysts for hydrocarbon o

  8. Biochemical DSB-repair model for mammalian cells in G1 and early S phases of the cell cycle.

    Science.gov (United States)

    Taleei, Reza; Nikjoo, Hooshang

    2013-08-30

    The paper presents a model of double strand breaks (DSB) repair in G1 and early S phases of the cell cycle. The model is based on a plethora of published information on biochemical modification of DSB induced by ionizing radiation. So far, three main DSB repair pathways have been identified, including nonhomologous end-joining (NHEJ), homologous recombination (HR), and microhomology-mediated end-joining (MMEJ). During G1 and early S phases of the cell cycle, NHEJ and MMEJ repair pathways are activated dependent on the type of double strand breaks. Simple DSB are a substrate for NHEJ, while complex DSB and DSB in heterochromatin require further end processing. Repair of all DSB start with NHEJ presynaptic processes, and depending on the type of DSB pursue simple ligation, further end processing prior to ligation, or resection. Using law of mass action the model is translated into a mathematical formalism. The solution of the formalism provides the step by step and overall repair kinetics. The overall repair kinetics are compared with the published experimental measurements. Our calculations are in agreement with the experimental results and show that the complex types of DSBs are repaired with slow repair kinetics. The G1 and early S phase model could be employed to predict the kinetics of DSB repair for damage induced by high LET radiation.

  9. Bioaccumulation and cancer risk of polycyclic aromatic hydrocarbons in leafy vegetables grown in soils within automobile repair complex and environ in Uyo, Nigeria.

    Science.gov (United States)

    Inam, Edu; Ibanga, Felicia; Essien, Joseph

    2016-12-01

    Using gas chromatography-mass spectrometry and an incremental lifetime cancer risks (ILCRs) assessment model, the bioaccumulation and cancer risk of 16 USEPA priority polycyclic aromatic hydrocarbons (PAHs) in leafy vegetables (Vernonia amygdalina and Lasianthera africanum) grown in soils within an automobile repair complex environment in Uyo, Nigeria was studied. The total PAHs concentrations recorded for soils ranged from 0.02 to 1.77 mg/kg. The highest level of 1.77 mg/kg was recorded for soils from the main automobile repair complex (site 1). Low molecular weight (LMW) PAHs were predominant although some high molecular weight (HMW) PAHs suites (0.04 mg/kg of chrysene and 0.04 of benzo[k]fluoranthene) were also found in site 1. The leafy vegetables accumulated PAHs were mostly LMW. Accumulation levels were similar but the extent of PAH uptake in vegetables was species dependent as V. amygdalina accumulated more (0.81 mg/kg). The bioaccumulation factors (BaFs) calculated ranged from 0.22 to 0.63 for L. africanum, and 0.18 to 0.55 for V. amygdalina in site 1 where high PAH levels were recorded in soil. Pearson correlation coefficient analysis revealed a strong positive relation between the PAH content of soil and the amount accumulated by L. africanum (r = 0.5) and V. amygdalina (r = 0.8) at p = 0.05. The vegetable's potential to bioaccumulate PAHs is indicative of their use as good bioindicators for PAH contamination in soil. Only two of the USEPA possible human carcinogenic PAHs were detected, and carcinogenic risk assessment based on occupational exposures to soil particles by adults revealed that the total risk level (7.17 × 10(-5)) contribution from incidental soil ingestion, dermal contact, and soil particle dust inhalation slightly exceed the USEPA acceptable limits (automobile repair complexes across Nigeria.

  10. Cell transformation and mutability of different genetic loci in mammalian cells by metabolically activated carcinogenic polycylic hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Huberman, E.

    1977-01-01

    Treatment of experimental animals with chemical carcinogens, including some polycyclic hydrocarbons, can result in the formation of malignant tumors. The process whereby some chemicals induce malignancy is as yet unknown. However, in a model system using mammalian cells in culture, it was possible to show that the chemical carcinogens induce malignant transformation rather than select for pre-existing tumor cells. In the process of the in vitro cell transformation, the normal cells, which have an oriented pattern of cell growth, a limited life-span in vitro, and are not tumorigenic, are converted into cells that have a hereditary random pattern of cell growth, the ability to grow continuously in culture, and the ability to form tumors in vivo. This stable heritable phenotype of the transformed cells is similar to that of cells derived from spontaneous or experimentally induced tumors. Such stable heritable phenotype changes may arise from alteration in gene expression due to a somatic mutation after interaction of the carcinogen with cellular DNA. In the present experiments we have shown that metabolically activated carcinogenic polycyclic hydrocarbons which have been shown to bind to cellular DNA induce somatic mutations at different genetic loci in mammalian cells and that there is a relationship between the degree of mutant induction and the degree of carcinogenicity of the different hydrocarbons tested.

  11. Self-potential and Complex Conductivity Monitoring of In Situ Hydrocarbon Remediation in Microbial Fuel Cell

    Science.gov (United States)

    Zhang, C.; Revil, A.; Ren, Z.; Karaoulis, M.; Mendonca, C. A.

    2013-12-01

    Petroleum hydrocarbon contamination of soil and groundwater in both non-aqueous phase liquid and dissolved forms generated from spills and leaks is a wide spread environmental issue. Traditional cleanup of hydrocarbon contamination in soils and ground water using physical, chemical, and biological remedial techniques is often expensive and ineffective. Recent studies show that the microbial fuel cell (MFC) can simultaneously enhance biodegradation of hydrocarbons in soil and groundwater and yield electricity. Non-invasive geophysical techniques such as self-potential (SP) and complex conductivity (induced polarization) have shown the potential to detect and characterize the nature of electron transport mechanism of in situ bioremediation of organic contamination plumes. In this study, we deployed both SP and complex conductivity in lab scale MFCs to monitor time-laps geophysical response of degradation of hydrocarbons by MFC. Two different sizes of MFC reactors were used in this study (DI=15 cm cylinder reactor and 94.5cm x 43.5 cm rectangle reactor), and the initial hydrocarbon concentration is 15 g diesel/kg soil. SP and complex conductivity measurements were measured using non-polarizing Ag/AgCl electrodes. Sensitivity study was also performed using COMSOL Multiphysics to test different electrode configurations. The SP measurements showed stronger anomalies adjacent to the MFC than locations afar, and both real and imaginary parts of complex conductivity are greater in areas close to MFC than areas further away and control samples without MFC. The joint use of SP and complex conductivity could in situ evaluate the dynamic changes of electrochemical parameters during this bioremediation process at spatiotemporal scales unachievable with traditional sampling methods. The joint inversion of these two methods to evaluate the efficiency of MFC enhanced hydrocarbon remediation in the subsurface.

  12. Mechanisms of renal cell repair and regeneration after acute renal failure.

    Science.gov (United States)

    Nony, Paul A; Schnellmann, Rick G

    2003-03-01

    In many cases, acute renal failure (ARF) is the result of proximal tubular cell injury and death and can arise in a variety of clinical situations, especially following renal ischemia and drug or toxicant exposure. Although much research has focused on the cellular events leading to ARF, less emphasis has been placed on the mechanisms of renal cell repair and regeneration, although ARF is reversed in over half of those who acquire it. Studies using in vivo and in vitro models have demonstrated the importance of proliferation, migration, and repair of physiological functions of injured renal proximal tubular cells (RPTC) in the reversal of ARF. Growth factors have been shown to produce migration and proliferation of injured RPTC, although the specific mechanisms through which growth factors promote renal regeneration in vivo are unclear. Recently, interactions between integrins and extracellular matrix proteins such as collagen IV were shown to promote the repair of physiological functions in injured RPTC. Specifically, collagen IV synthesis and deposition following cellular injury restored integrin polarity and promoted repair of mitochondrial function and active Na(+) transport. Furthermore, exogenous collagen IV, but not collagen I, fibronectin, or laminin, promoted the repair of physiological functions without stimulating proliferation. These findings suggest the importance of establishing and/or maintaining collagen IV-integrin interactions in the stimulation of repair of physiological functions following sublethal cellular injury. Furthermore, the pathway that stimulates repair is distinct from that of proliferation and migration and may be a viable target for pharmacological intervention.

  13. New patterns of bulk DNA repair in ultraviolet irradiated mouse embryo carcinoma cells following differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Rasko, I.; Georgieva, M.; Farkas, G.; Santhan, M.; Burg, K. (Genetics Institute, Szeged (Hungary)); Coates, J.; Johnson, R.T. (Univ. of Cambridge (United Kingdom)); Mitchell, D.L. (M.D. Anderson Cancer Center, Smithville, TX (United States))

    1993-05-01

    Mouse embryocarcinoma stem cells differentiate in culture, given the appropriate induction. The authors examined whether these cells could provide information about the regulation of nucleotide excision repair in relation to differentiation by measuring the rate-limiting incision step, the removal of cyclobutane dimers and (6-4) photoproducts from the genome as a whole and the effect of the bacteriophage T4 endonuclease (denV) gene on repair in differentiated cells. It was found that differentiation is accompanied by a marked decline in the early incision ability after UV irradiation (sixfold for P19, fourfold for PCC7 and twofold for F9), and the authors measured, in parallel, the loss of two common UV photoproducts [cyclobutane dimers and (6-4) photoproducts] from P19 cells. After differentiation, the excellent overall cyclobutane dimer repair capacity of proliferating cells (84% removal in 24 h) is lost (no removal in 24 h), while removal of (6-4) photoproducts, although normal at 24 h (94%), is much slower than in undifferentiated P19 at 3 h (no removal versus 64%). The presence of the denV gene greatly stimulates the repair of cyclobutane dimers in undifferentiated P19 cells (94% removal at 3 h vs. no removal) and also in differentiated cells (50% removal at 24 h vs. no removal). The denV gene also stimulates the early repair of (6-4) photoproducts in both differentiated and undifferentiated cells.

  14. Enhancement of DNA repair capacity of mammalian cells by carcinogen treatment

    Energy Technology Data Exchange (ETDEWEB)

    Protic, M.; Roilides, E.; Levine, A.S.; Dixon, K.

    1988-07-01

    To determine whether DNA excision repair is enhanced in mammalian cells in response to DNA damage, as it is in bacteria as part of the SOS response, we used an expression vector-host cell reactivation assay to measure cellular DNA repair capacity. When UV-damaged chloramphenicol acetyltransferase (CAT) vector DNA was introduced into monkey cells (CV-1), the level of CAT activity was inversely related to the UV fluence due to inhibition of CAT gene expression by UV photoproducts. When CV-1 cells were treated with either UV radiation or mitomycin C, 24-48 h before transfection, CAT expression from the UV-irradiated plasmid was increased. This increase also occurred in a line of normal human cells, but not in repair-deficient human xeroderma pigmentosum cells. We confirmed that this increase in CAT expression was due to repair, and not to production of damage-free templates by recombination; the frequency of generation of supF+ recombinants after transfection with UV-irradiated pZ189 vectors carrying different point mutations in the supF gene did not significantly increase in carcinogen-treated CV-1 cells. From these results we conclude that carcinogen treatment enhances the excision-repair capacity of normal mammalian cells.

  15. Solid Oxide Fuel Cell Operating on Hydrocarbon Fuel Project

    Data.gov (United States)

    National Aeronautics and Space Administration — One objective is to make structural and compositional changes to the largest electrical resistance element of the cell, the electrolyte. And the second objective is...

  16. The aryl hydrocarbon receptor-dependent deregulation of cell cycle control induced by polycyclic aromatic hydrocarbons in rat liver epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Andrysik, Zdenek [Laboratory of Cytokinetics, Institute of Biophysics, 612 65 Brno (Czech Republic); Department of Chemistry and Toxicology, Veterinary Research Institute, 621 32 Brno (Czech Republic); Vondracek, Jan [Laboratory of Cytokinetics, Institute of Biophysics, 612 65 Brno (Czech Republic) and Department of Chemistry and Toxicology, Veterinary Research Institute, 621 32 Brno (Czech Republic)]. E-mail: vondracek@ibp.cz; Machala, Miroslav [Department of Chemistry and Toxicology, Veterinary Research Institute, 621 32 Brno (Czech Republic); Krcmar, Pavel [Department of Chemistry and Toxicology, Veterinary Research Institute, 621 32 Brno (Czech Republic); Svihalkova-Sindlerova, Lenka [Laboratory of Cytokinetics, Institute of Biophysics, 612 65 Brno (Czech Republic); Kranz, Anne [Institute of Toxicology, Johannes Gutenberg-University, 55131 Mainz (Germany); Weiss, Carsten [Institute of Toxicology, Johannes Gutenberg-University, 55131 Mainz (Germany); Faust, Dagmar [Institute of Toxicology, Johannes Gutenberg-University, 55131 Mainz (Germany); Kozubik, Alois [Laboratory of Cytokinetics, Institute of Biophysics, 612 65 Brno (Czech Republic); Dietrich, Cornelia [Institute of Toxicology, Johannes Gutenberg-University, 55131 Mainz (Germany)

    2007-02-03

    Disruption of cell proliferation control by polycyclic aromatic hydrocarbons (PAHs) may contribute to their carcinogenicity. We investigated role of the aryl hydrocarbon receptor (AhR) in disruption of contact inhibition in rat liver epithelial WB-F344 'stem-like' cells, induced by the weakly mutagenic benz[a]anthracene (BaA), benzo[b]fluoranthene (BbF) and by the strongly mutagenic benzo[a]pyrene (BaP). There were significant differences between the effects of BaA and BbF, and those of the strongly genotoxic BaP. Both BaA and BbF increased percentage of cells entering S-phase and cell numbers, associated with an increased expression of Cyclin A and Cyclin A/cdk2 complex activity. Their effects were significantly reduced in cells expressing a dominant-negative AhR mutant (dnAhR). Roscovitine, a chemical inhibitor of cdk2, abolished the induction of cell proliferation by BbF. However, neither BaA nor BbF modulated expression of the principal cdk inhibitor involved in maintenance of contact inhibition, p27{sup Kip1}, or pRb phosphorylation. The strongly mutagenic BaP induced apoptosis, a decrease in total cell numbers and significantly higher percentage of cells entering S-phase than either BaA or BbF. Given that BaP induced high levels of Cyclin A/cdk2 activity, downregulation of p27{sup Kip1} and hyperphosphorylation of pRb, the accumulation of cells in S-phase was probably due to cell proliferation, although S-phase arrest due to blocked replication forks can not be excluded. Both types of effects of BaP were significantly attenuated in dnAhR cells. Transfection of WB-F344 cells with siRNA targeted against AhR decreased induction of Cyclin A induced by BbF or BaP, further supporting the role of AhR in proliferative effects of PAHs. This suggest that activation of AhR plays a significant role both in disruption of contact inhibition by weakly mutagenic PAHs and in genotoxic effects of BaP possibly leading to enhanced cell proliferation. Thus, PAHs may

  17. Docosahexaenoic acid regulates gene expression in HUVEC cells treated with polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Gdula-Argasińska, Joanna; Czepiel, Jacek; Totoń-Żurańska, Justyna; Jurczyszyn, Artur; Perucki, William; Wołkow, Paweł

    2015-07-16

    The molecular mechanism of inflammation and carcinogenesis induced by exposure of polycyclic aromatic hydrocarbons (PAHs) is not clearly understood. Our study was undertaken due to the strong pro-carcinogenic potential and reactivity of PAH-metabolites, as well as the susceptibility of polyunsaturated fatty acids to oxidation. The aim of this study was to evaluate the pro- or anti-inflammatory impact of n-3 docosahexaenoic acid on human primary umbilical vein endothelial cells (HUVEC) exposed to polycyclic aromatic hydrocarbons. We analysed the influence of docosahexaenoic acid (DHA) and/or PAHs supplementation on the fatty acid profile of cell membranes, on cyclooxygenase-2 (COX-2), aryl hydrocarbon receptor (AHR), and glutathione S transferase Mu1 (GSTM1) protein expression as well as on the prostaglandin synthase 2 (PTGS2), AHR, GSTM1, PLA2G4A, and cytochrome P450 CYP1A1 gene expression. We observed that COX-2 and AHR protein expression was increased while GSTM1 expression was decreased in cells exposed to DHA and PAHs. Docosahexaenoic acid down-regulated CYP1A1 and up-regulated the AHR and PTGS2 genes. Our findings suggested that DHA contributes significantly to alleviate the harmful effects caused by PAHs in endothelial cells. Moreover, these results suggest that a diet rich in n-3 fatty acids is helpful to reduce the harmful effects of PAHs exposure on human living in heavily polluted areas.

  18. Intrinsic repair protects cells from pore-forming toxins by microvesicle shedding.

    Science.gov (United States)

    Romero, Matthew; Keyel, Michelle; Shi, Guilan; Bhattacharjee, Pushpak; Roth, Robyn; Heuser, John E; Keyel, Peter A

    2017-02-10

    Pore-forming toxins (PFTs) are used by both the immune system and by pathogens to disrupt cell membranes. Cells attempt to repair this disruption in various ways, but the exact mechanism(s) that cells use are not fully understood, nor agreed upon. Current models for membrane repair include (1) patch formation (e.g., fusion of internal vesicles with plasma membrane defects), (2) endocytosis of the pores, and (3) shedding of the pores by blebbing from the cell membrane. In this study, we sought to determine the specific mechanism(s) that cells use to resist three different cholesterol-dependent PFTs: Streptolysin O, Perfringolysin O, and Intermedilysin. We found that all three toxins were shed from cells by blebbing from the cell membrane on extracellular microvesicles (MVs). Unique among the cells studied, we found that macrophages were 10 times more resistant to the toxins, yet they shed significantly smaller vesicles than the other cells. To examine the mechanism of shedding, we tested whether toxins with engineered defects in pore formation or oligomerization were shed. We found that oligomerization was necessary and sufficient for membrane shedding, suggesting that calcium influx and patch formation were not required for shedding. However, pore formation enhanced shedding, suggesting that calcium influx and patch formation enhance repair. In contrast, monomeric toxins were endocytosed. These data indicate that cells use two interrelated mechanisms of membrane repair: lipid-dependent MV shedding, which we term 'intrinsic repair', and patch formation by intracellular organelles. Endocytosis may act after membrane repair is complete by removing inactivated and monomeric toxins from the cell surface.Cell Death and Differentiation advance online publication, 10 February 2017; doi:10.1038/cdd.2017.11.

  19. Repair of DNA lesions induced by ultraviolet irradiation and aromatic amines in normal and repair-deficient human lymphoblastoid cell lines

    DEFF Research Database (Denmark)

    Stevnsner, Tinna; Frandsen, Henrik; Autrup, Herman

    1995-01-01

    A host cell reactivation (HCR) assay was employed to study the capacity of a normal and three repair-deficient human lymphoblastoid cell lines to repair DNA damage induced by UV irradiation and the aromatic amines 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and N-acetyl-2-aminofluorene....... In the XP-D cell line, which had practically no DNA repair capacity, AAF adducts had a more potent inhibitory effect on gene expression than UV and PhIP adducts. When corrected for this inhibitory effect, the wild-type, XP-C and CS-B cell lines repaired low levels of AAF and UV adducts with similar...

  20. Half-cell potential mapping to assess repair work on RC structures

    Energy Technology Data Exchange (ETDEWEB)

    Elsener, B. [Cagliari Univ., Dept. of Materials Science (Italy)

    2000-07-01

    Results on the successful use and on the limitations of half-cell potential mapping as an assessment technique after completion of repair work on a concrete structure are reviewed. Examples of repair discussed include traditional repair, electrochemical chloride removal, electrochemical realkalization and the application of surface applied corrosion inhibitors. Results indicate that half-cell potential measurements after traditional repair work or electrochemical chloride removal provide direct evidence of repassivation of the rebars when performed several weeks after the repair work (readings during the first few days after repair tend to show very negative potentials). Special attention must be given to the use of polymer-modified mortars when used in surface treatment of rebars; half-cell potential could remain permanently negative due to restricted oxygen access. Half-cell potential measurements are not considered effective in measuring the efficiency and durability of surface applied corrosion inhibitors due to pore solution pH and composition, and the mostly unknown mechanism of action of inhibitor blends. 18 refs., 8 figs.

  1. Genetic characterization of cells of homocystinuria patients with disrupted DNA repair system

    Energy Technology Data Exchange (ETDEWEB)

    Sinel' shchikova, T.A.; L' vova, G.N.; Shoniya, N.N.; Zasukhina, G.D.

    1986-08-01

    Fibroblasts obtained from biopsy material and lymphocytes of patients with homocystinuria were investigated for repair activity according to the following criteria: rejoined DNA breaks, induced by 4-nitroquinoline-1-oxide and ..gamma..-radiation; indices of reactivation and induced mutagenesis of smallpox vaccine virus treated with these mutagens. In lymphocytes a defect of DNA repair was observed according to all criteria investigated. During passage of fibroblast cultures, inhibition of repair activity of cells was preserved according to ..gamma..-type. Increase in the number of spontaneous and ..gamma..-induced mutations of virus was noted according to degree of passage of fibroblasts.

  2. Nrf2 facilitates repair of radiation induced DNA damage through homologous recombination repair pathway in a ROS independent manner in cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, Sundarraj; Pal, Debojyoti; Sandur, Santosh K., E-mail: sskumar@barc.gov.in

    2015-09-15

    Highlights: • Nrf2 inhibition in A549 cells led to attenuated DNA repair and radiosensitization. • Influence of Nrf2 on DNA repair is not linked to its antioxidant function. • Nrf2 influences DNA repair through homologous recombination (HR) repair pathway. • Many genes involved in HR pathway show ARE sequences in their upstream region. - Abstract: Nrf2 is a redox sensitive transcription factor that is involved in the co-ordinated transcription of genes involved in redox homeostasis. But the role of Nrf2 in DNA repair is not investigated in detail. We have employed A549 and MCF7 cells to study the role of Nrf2 on DNA repair by inhibiting Nrf2 using all-trans retinoic acid (ATRA) or by knock down approach prior to radiation exposure (4 Gy). DNA damage and repair analysis was studied by γH2AX foci formation and comet assay. Results suggested that the inhibition of Nrf2 in A549 or MCF7 cells led to significant slowdown in DNA repair as compared to respective radiation controls. The persistence of residual DNA damage even in the presence of free radical scavenger N-acetyl cysteine, suggested that the influence of Nrf2 on DNA repair was not linked to its antioxidant functions. Further, its influence on non-homologous end joining repair pathway was studied by inhibiting both Nrf2 and DNA-PK together. This led to synergistic reduction of survival fraction, indicating that Nrf2 may not be influencing the NHEJ pathway. To investigate the role of homologous recombination repair (HR) pathway, RAD51 foci formation was monitored. There was a significant reduction in the foci formation in cells treated with ATRA or shRNA against Nrf2 as compared to their respective radiation controls. Further, Nrf2 inhibition led to significant reduction in mRNA levels of RAD51. BLAST analysis was also performed on upstream regions of DNA repair genes to identify antioxidant response element and found that many repair genes that are involved in HR pathway may be regulated by Nrf2

  3. Bone marrow-derived cells in renal repair

    NARCIS (Netherlands)

    Broekema, Martine

    2007-01-01

    The kidney can recover after acute renal injury due to its highly effective endogenous regenerative capacity. However, under certain conditions the balance between injury and repair can get disturbed. This can ultimately lead to chronic renal failure, which is an increasing problem in the clinical s

  4. Cell specific effects of PCB 126 on aryl hydrocarbone receptors in follicular cells of porcine ovaries

    Energy Technology Data Exchange (ETDEWEB)

    Wojtowicz, A.; Augustowska, K.; Gregoraszczuk, E. [Lab. of Physiology and Toxicology of Reproduction, Dept. of Animal Physiology, Inst. of Zoology, Jagiellonian Univ., Krakow (Poland)

    2004-09-15

    Polychlorinated biphenyles (PCBs) like other endocrine disrupters could interfere with natural hormones by binding to their receptors and thus mimicking the cellular response to them. They are known to possess either estrogenic or antiestrogenic properties. In our previous papers we demonstrated that PCBs are able to disrupt ovarian steroidogenesis. We found that the coplanar PCB 126 caused the decrease in estradiol secretion in whole cultured pig ovarian follicles. PCB 126 congener is structurally related to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Since TCDD effects are known to be mediated by aryl hydrocarbone receptors (AhRs), we decided to determine if PCB 126 affects signal transduction pathway activated by these receptors. It has been reported that the functional AhR is present in ovary including oocytes, granulosa and theca cells of rat, mouse, rhesus monkey and human ovary. Moreover, the expression of AhR in the rat ovary appeared to be estrous cycle-dependent, thus suggesting that AhR expression may be regulated by fluctuating hormone levels. This study was designed to investigate the effects of the non-ortho-substituted 3,3',4,4',5-pentachlorobiphenyl (PCB126) on the AhR activation, localization and protein level in pig ovarian follicle cells.

  5. Exposure to runoff from coal-tar-sealed pavement induces genotoxicity and impairment of DNA repair capacity in the RTL-W1 fish liver cell line

    Science.gov (United States)

    Kienzler, Aude; Mahler, Barbara J.; Van Metre, Peter C.; Schweigert, Nathalie; Devaux, Alain; Bony, Sylvie

    2015-01-01

    Coal-tar-based (CTB) sealcoat, frequently applied to parking lots and driveways in North America, contains elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) and related compounds. The RTL-W1 fish liver cell line was used to investigate two endpoints (genotoxicity and DNA-repair-capacity impairment) associated with exposure to runoff from asphalt pavement with CTB sealcoat or with an asphalt-based sealcoat hypothesized to contain about 7% CTB sealcoat (AS-blend). Genotoxic potential was assessed by the Formamido pyrimidine glycosylase (Fpg)-modified comet assay for 1:10 and 1:100 dilutions of runoff samples collected from 5 h to 36 d following sealcoat application. DNA-repair capacity was assessed by the base excision repair comet assay for 1:10 dilution of samples collected 26 h and 36 d following application. Both assays were run with and without co-exposure to ultraviolet-A radiation (UVA). With co-exposure to UVA, genotoxic effects were significant for both dilutions of CTB runoff for three of four sample times, and for some samples of AS-blend runoff. Base excision repair was significantly impaired for CTB runoff both with and without UVA exposure, and for AS-blend runoff only in the absence of UVA. This study is the first to investigate the effects of exposure to the complex mixture of chemicals in coal tar on DNA repair capacity. The results indicate that co-exposure to runoff from CT-sealcoated pavement and UVA as much as a month after sealcoat application has the potential to cause genotoxicity and impair DNA repair capacity.

  6. Effect of Delayed Peripheral Nerve Repair on Nerve Regeneration, Schwann Cell Function and Target Muscle Recovery

    Science.gov (United States)

    Jonsson, Samuel; Wiberg, Rebecca; McGrath, Aleksandra M.; Novikov, Lev N.; Wiberg, Mikael; Novikova, Liudmila N.; Kingham, Paul J.

    2013-01-01

    Despite advances in surgical techniques for peripheral nerve repair, functional restitution remains incomplete. The timing of surgery is one factor influencing the extent of recovery but it is not yet clearly defined how long a delay may be tolerated before repair becomes futile. In this study, rats underwent sciatic nerve transection before immediate (0) or 1, 3, or 6 months delayed repair with a nerve graft. Regeneration of spinal motoneurons, 13 weeks after nerve repair, was assessed using retrograde labeling. Nerve tissue was also collected from the proximal and distal stumps and from the nerve graft, together with the medial gastrocnemius (MG) muscles. A dramatic decline in the number of regenerating motoneurons and myelinated axons in the distal nerve stump was observed in the 3- and 6-months delayed groups. After 3 months delay, the axonal number in the proximal stump increased 2–3 folds, accompanied by a smaller axonal area. RT-PCR of distal nerve segments revealed a decline in Schwann cells (SC) markers, most notably in the 3 and 6 month delayed repair samples. There was also a progressive increase in fibrosis and proteoglycan scar markers in the distal nerve with increased delayed repair time. The yield of SC isolated from the distal nerve segments progressively fell with increased delay in repair time but cultured SC from all groups proliferated at similar rates. MG muscle at 3- and 6-months delay repair showed a significant decline in weight (61% and 27% compared with contra-lateral side). Muscle fiber atrophy and changes to neuromuscular junctions were observed with increased delayed repair time suggestive of progressively impaired reinnervation. This study demonstrates that one of the main limiting factors for nerve regeneration after delayed repair is the distal stump. The critical time point after which the outcome of regeneration becomes too poor appears to be 3-months. PMID:23409189

  7. Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair.

    Science.gov (United States)

    Gustafsson, Ann-Sofie; Abramenkovs, Andris; Stenerlöw, Bo

    2014-11-01

    Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80-95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure which is uncoupled from its essential function in DSB repair. This could have implications for the development of therapeutic strategies aiming to radiosensitize tumors by affecting the DNA-PKcs function.

  8. Exome-wide somatic microsatellite variation is altered in cells with DNA repair deficiencies.

    Directory of Open Access Journals (Sweden)

    Zalman Vaksman

    Full Text Available Microsatellites (MST, tandem repeats of 1-6 nucleotide motifs, are mutational hot-spots with a bias for insertions and deletions (INDELs rather than single nucleotide polymorphisms (SNPs. The majority of MST instability studies are limited to a small number of loci, the Bethesda markers, which are only informative for a subset of colorectal cancers. In this paper we evaluate non-haplotype alleles present within next-gen sequencing data to evaluate somatic MST variation (SMV within DNA repair proficient and DNA repair defective cell lines. We confirm that alleles present within next-gen data that do not contribute to the haplotype can be reliably quantified and utilized to evaluate the SMV without requiring comparisons of matched samples. We observed that SMV patterns found in DNA repair proficient cell lines without DNA repair defects, MCF10A, HEK293 and PD20 RV:D2, had consistent patterns among samples. Further, we were able to confirm that changes in SMV patterns in cell lines lacking functional BRCA2, FANCD2 and mismatch repair were consistent with the different pathways perturbed. Using this new exome sequencing analysis approach we show that DNA instability can be identified in a sample and that patterns of instability vary depending on the impaired DNA repair mechanism, and that genes harboring minor alleles are strongly associated with cancer pathways. The MST Minor Allele Caller used for this study is available at https://github.com/zalmanv/MST_minor_allele_caller.

  9. A novel method for monitoring functional lesion-specific recruitment of repair proteins in live cells

    Energy Technology Data Exchange (ETDEWEB)

    Woodrick, Jordan; Gupta, Suhani; Khatkar, Pooja; Dave, Kalpana; Levashova, Darya; Choudhury, Sujata; Elias, Hadi; Saha, Tapas; Mueller, Susette; Roy, Rabindra, E-mail: rr228@georgetown.edu

    2015-05-15

    Highlights: • A method of monitoring lesion-specific recruitment of proteins in vivo is described. • Recruitment of repair enzymes to abasic sites is monitored by co-localization. • Repair protein recruitment is consistent with known protein–protein relationships. • Cells demonstrated complete repair of abasic sites by 90 min. - Abstract: DNA–protein relationships have been studied by numerous methods, but a particular gap in methodology lies in the study of DNA adduct-specific interactions with proteins in vivo, which particularly affects the field of DNA repair. Using the repair of a well-characterized and ubiquitous adduct, the abasic (AP) site, as a model, we have developed a comprehensive method of monitoring DNA lesion-specific recruitment of proteins in vivo over time. We utilized a surrogate system in which a Cy3-labeled plasmid containing a single AP-site was transfected into cells, and the interaction of the labeled DNA with BER enzymes, including APE1, Polβ, LIG1, and FEN1, was monitored by immunofluorescent staining of the enzymes by Alexafluor-488-conjugated secondary antibody. The recruitment of enzymes was characterized by quantification of Cy3-Alexafluor-488 co-localization. To validate the microscopy-based method, repair of the transfected AP-site DNA was also quantified at various time points post-transfection using a real time PCR-based method. Notably, the recruitment time kinetics for each enzyme were consistent with AP-site repair time kinetics. This microscopy-based methodology is reliable in detecting the recruitment of proteins to specific DNA substrates and can be extended to study other in vivo DNA–protein relationships in any DNA sequence and in the context of any DNA structure in transfectable proliferating or quiescent cells. The method may be applied to a variety of disciplines of nucleic acid transaction pathways, including repair, replication, transcription, and recombination.

  10. BLM has early and late functions in homologous recombination repair in mouse embryonic stem cells

    DEFF Research Database (Denmark)

    Chu, W K; Hanada, K; Kanaar, R;

    2010-01-01

    function of BLM remains unclear. Multiple roles have been proposed for BLM in the homologous recombination (HR) repair pathway, including 'early' functions, such as the stimulation of resection of DNA double-strand break ends or displacement of the invading strand of DNA displacement loops, and 'late...... in Rad54(-/-) cells rescued their mitomycin C (MMC) sensitivity, and decreased both the level of DNA damage and cell cycle perturbation induced by MMC, suggesting an early role for Blm. Our data are consistent with Blm having at least two roles in HR repair in mammalian cells....

  11. Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair

    Energy Technology Data Exchange (ETDEWEB)

    Gustafsson, Ann-Sofie, E-mail: ann-sofie.gustafsson@bms.uu.se; Abramenkovs, Andris; Stenerlöw, Bo

    2014-11-15

    Highlights: • We reduced the level of DNA-PKcs with siRNA and examined cells after γ-irradiation. • Low DNA-PKcs levels lead to radiosensitivity but did not affect repair of DSB. • Low DNA-PKcs levels may block progression of mitosis. • DNA-PKcs role in mitotic progression is independent of its role in DSB repair. • We suggest different mechanisms by which loss of DNA-PKcs function sensitize cells. - Abstract: Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80–95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure

  12. Adipose, Bone Marrow and Synovial Joint-Derived Mesenchymal Stem Cells for Cartilage Repair

    Science.gov (United States)

    Fellows, Christopher R.; Matta, Csaba; Zakany, Roza; Khan, Ilyas M.; Mobasheri, Ali

    2016-01-01

    Current cell-based repair strategies have proven unsuccessful for treating cartilage defects and osteoarthritic lesions, consequently advances in innovative therapeutics are required and mesenchymal stem cell-based (MSC) therapies are an expanding area of investigation. MSCs are capable of differentiating into multiple cell lineages and exerting paracrine effects. Due to their easy isolation, expansion, and low immunogenicity, MSCs are an attractive option for regenerative medicine for joint repair. Recent studies have identified several MSC tissue reservoirs including in adipose tissue, bone marrow, cartilage, periosteum, and muscle. MSCs isolated from these discrete tissue niches exhibit distinct biological activities, and have enhanced regenerative potentials for different tissue types. Each MSC type has advantages and disadvantages for cartilage repair and their use in a clinical setting is a balance between expediency and effectiveness. In this review we explore the challenges associated with cartilage repair and regeneration using MSC-based cell therapies and provide an overview of phenotype, biological activities, and functional properties for each MSC population. This paper also specifically explores the therapeutic potential of each type of MSC, particularly focusing on which cells are capable of producing stratified hyaline-like articular cartilage regeneration. Finally we highlight areas for future investigation. Given that patients present with a variety of problems it is unlikely that cartilage regeneration will be a simple “one size fits all,” but more likely an array of solutions that need to be applied systematically to achieve regeneration of a biomechanically competent repair tissue. PMID:28066501

  13. Repair of tracheal epithelium by basal cells after chlorine-induced injury

    Directory of Open Access Journals (Sweden)

    Musah Sadiatu

    2012-11-01

    Full Text Available Abstract Background Chlorine is a widely used toxic compound that is considered a chemical threat agent. Chlorine inhalation injures airway epithelial cells, leading to pulmonary abnormalities. Efficient repair of injured epithelium is necessary to restore normal lung structure and function. The objective of the current study was to characterize repair of the tracheal epithelium after acute chlorine injury. Methods C57BL/6 mice were exposed to chlorine and injected with 5-ethynyl-2′-deoxyuridine (EdU to label proliferating cells prior to sacrifice and collection of tracheas on days 2, 4, 7, and 10 after exposure. Airway repair and restoration of a differentiated epithelium were examined by co-localization of EdU labeling with markers for the three major tracheal epithelial cell types [keratin 5 (K5 and keratin 14 (K14 for basal cells, Clara cell secretory protein (CCSP for Clara cells, and acetylated tubulin (AcTub for ciliated cells]. Morphometric analysis was used to measure proliferation and restoration of a pseudostratified epithelium. Results Epithelial repair was fastest and most extensive in proximal trachea compared with middle and distal trachea. In unexposed mice, cell proliferation was minimal, all basal cells expressed K5, and K14-expressing basal cells were absent from most sections. Chlorine exposure resulted in the sloughing of Clara and ciliated cells from the tracheal epithelium. Two to four days after chlorine exposure, cell proliferation occurred in K5- and K14-expressing basal cells, and the number of K14 cells was dramatically increased. In the period of peak cell proliferation, few if any ciliated or Clara cells were detected in repairing trachea. Expression of ciliated and Clara cell markers was detected at later times (days 7–10, but cell proliferation was not detected in areas in which these differentiated markers were re-expressed. Fibrotic lesions were observed at days 7–10 primarily in distal trachea. Conclusion

  14. Signaling factors in stem cell-mediated repair of infarcted myocardium

    NARCIS (Netherlands)

    Vandervelde, S; van Luyn, MJA; Tio, RA; Harmsen, MC

    2005-01-01

    Myocardial infarction leads to scar formation and subsequent reduced cardiac performance. The ultimate therapy after myocardial infarction would pursue stem cell-based regeneration. The aim of stem cell-mediated cardiac repair embodies restoration of cardiac function by regeneration of healthy myoca

  15. Insulin-like growth factor-1 sustains stem cell mediated renal repair.

    NARCIS (Netherlands)

    Imberti, B.; Morigi, M.; Tomasoni, S.; Rota, C.; Corna, D.; Longaretti, L.; Rottoli, D.; Valsecchi, F.; Benigni, A.; Wang, J.; Abbate, M.; Zoja, C.; Remuzzi, G.

    2007-01-01

    In mice with cisplatin-induced acute kidney injury, administration of bone marrow-derived mesenchymal stem cells (MSC) restores renal tubular structure and improves renal function, but the underlying mechanism is unclear. Here, we examined the process of kidney cell repair in co-culture experiments

  16. Human embryonic stem cells have enhanced repair of multiple forms of DNA damage

    DEFF Research Database (Denmark)

    Maynard, Scott; Swistowska, Anna Maria; Lee, Jae Wan

    2008-01-01

    fibroblasts (WI-38, hs27) and, with the exception of UV-C damage, HeLa cells. Microarray gene expression analysis showed that mRNA levels of several DNA repair genes are elevated in human embryonic stem cells compared with their differentiated forms (embryoid bodies). These data suggest that genomic...

  17. Neural stem cell transplantation in the repair of spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Neural stem cells are a pronising candidate for neural transplantation aimed at neural cell replacement and repair of the damaged host central nervous system (CNS). Recent studies using neural stem cells have shown that implanted neural stem cells can effectively incorporate into the damaged CNS and differentiate into neurons, astrocytes, and oligodendrocytes. The recent explosion in the field of neural stem cell research has provided insight into the inductive factors influencing neural stem cell differentiation and may yield potential therapies for several neurological disorders, including spinal cord injury. In this review, we summarize recent studies involving neural stem cell biology in both rodents and humans. We also discuss unique advantages and possible mechanisms of using neural stem cell trans plantation in the repair of spinal cord injury.

  18. Modification of cell surface properties of Pseudomonas alcaligenes S22 during hydrocarbon biodegradation.

    Science.gov (United States)

    Kaczorek, Ewa; Moszyńska, Sylwia; Olszanowski, Andrzej

    2011-04-01

    Biodegradation of water insoluble hydrocarbons can be significantly increased by the addition of natural surfactants one. Very promising option is the use of saponins. The obtained results indicated that in this system, after 21 days, 92% biodegradation of diesel oil could be achieved using Pseudomonas alcaligenes. No positive effect on the biodegradation process was observed using synthetic surfactant Triton X-100. The kind of carbon source influences the cell surface properties of microorganisms. Modification of the surface cell could be observed by control of the sedimentation profile. This analytical method is a new approach in microbiological analysis.

  19. Potentially lethal damage repair by total and quiescent tumor cells following various DNA-damaging treatments

    Energy Technology Data Exchange (ETDEWEB)

    Masunaga, Shin-ichiro; Ono, Koji; Suzuki, Minoru; Kinashi, Yuko; Takagaki, Masao [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Hori, Hitoshi; Kasai, Soko; Nagasawa, Hideko; Uto, Yoshihiro

    1999-08-01

    After continuous labeling of proliferating (P) cells with 5-bromo-2'-deoxyuridine (BrdU) for 5 days, SCC VII tumor-bearing mice received various kinds of DNA-damaging treatments: gamma-ray irradiation, tirapazamine (TPZ, hypoxia-specific cytotoxin) administration, or cisplatin injection. From 0.5 to 72 hr after treatment, tumors were excised, minced, and trypsinized. Single tumor cell suspensions were incubated for 48 hr with a cytokinesis-blocker, cytochalasin-B. Then, the micronucleus (MN) frequency for BrdU-unlabeled cells, quiescent (Q) cells at treatment, was determined using immunofluorescence staining for BrdU. The MN frequency for total (P+Q) cells was obtained from tumors that were not pretreated with BrdU labeling. The sensitivity to each DNA-damaging treatment was evaluated in terms of the frequency of induced micronuclei in binuclear tumor cells (MN frequency). Treatment with gamma-rays or cisplatin resulted in a larger MN frequency in total cells than in Q cells. In contrast, TPZ treatment produced a smaller MN frequency in total cells than in Q cells. Regardless of the treatment used, Q cells showed greater repair capacities than total cells. However, TPZ caused much smaller repair capacity in both total and Q cells, compared with gamma-rays or cisplatin. Gamma-rays and cisplatin produced similar repair patterns. Differences in sensitivity between total and Q cells and repair patterns of the two cell populations were thought to depend on differences between the two cell populations in the toxicity of the DNA-damaging treatment and distribution pattern of the anticancer agent. (author)

  20. Human POLD1 modulates cell cycle progression and DNA damage repair

    OpenAIRE

    Song, Jing; Hong, Ping; Liu, Chengeng; Zhang, Yueqi; Wang, Jinling; Wang, Peichang

    2015-01-01

    Background The activity of eukaryotic DNA polymerase delta (Pol ?) plays an essential role in genome stability through its effects on DNA replication and repair. The p125 catalytic subunit of Pol ? is encoded by POLD1 gene in human cells. To clarify biological functions of POLD1, we investigated the effects of POLD1 overexpression or downregulation on cell proliferation, cell cycle progression, DNA synthesis and oxidative DNA damage induced by H2O2. Methods HEK293 cells were transfected with ...

  1. Cells Resistant to Toxic Concentrations of Manganese Have Increased Ability to Repair DNA.

    Science.gov (United States)

    Zakharcheva, K A; Gening, L V; Kazachenko, K Yu; Tarantul, V Z

    2017-01-01

    Manganese (Mn) is crucially important for vital activity of cells and has many biological functions. Nevertheless, high doses of Mn taken up by an organism over a long period may cause neurodegenerative diseases such as manganism and Parkinsonism. The molecular mechanisms of this Mn toxicity are still poorly studied. It is now believed that Mn-induced pathophysiological neural processes are multifaceted and affect several metabolic pathways. In particular, Mn ions might affect the processes of DNA replication and repair. To test this possibility, we obtained an SKOV-3 cell line resistant to the toxic action of Mn ions. We found that these cells are characterized by the activation of poly(ADP-ribose)polymerase, which leads to increased ability to repair DNA. Thus, the model used here supports the suggestion that at least one cause of Mn cytotoxicity might be disorders of the processes involved in DNA replication and repair.

  2. Prospect of Induced Pluripotent Stem Cell Genetic Repair to Cure Genetic Diseases

    Directory of Open Access Journals (Sweden)

    Jeanne Adiwinata Pawitan

    2012-01-01

    Full Text Available In genetic diseases, where the cells are already damaged, the damaged cells can be replaced by new normal cells, which can be differentiated from iPSC. To avoid immune rejection, iPSC from the patient’s own cell can be developed. However, iPSC from the patients’s cell harbors the same genetic aberration. Therefore, before differentiating the iPSCs into required cells, genetic repair should be done. This review discusses the various technologies to repair the genetic aberration in patient-derived iPSC, or to prevent the genetic aberration to cause further damage in the iPSC-derived cells, such as Zn finger and TALE nuclease genetic editing, RNA interference technology, exon skipping, and gene transfer method. In addition, the challenges in using the iPSC and the strategies to manage the hurdles are addressed.

  3. Inflammation and the Intestinal Barrier: Leukocyte–Epithelial Cell Interactions, Cell Junction Remodeling, and Mucosal Repair

    Science.gov (United States)

    Luissint, Anny-Claude; Parkos, Charles A.; Nusrat, Asma

    2017-01-01

    The intestinal tract is lined by a single layer of columnar epithelial cells that forms a dynamic, permeable barrier allowing for selective absorption of nutrients, while restricting access to pathogens and food-borne antigens. Precise regulation of epithelial barrier function is therefore required for maintaining mucosal homeostasis and depends, in part, on barrier-forming elements within the epithelium and a balance between pro- and anti-inflammatory factors in the mucosa. Pathologic states, such as inflammatory bowel disease, are associated with a leaky epithelial barrier, resulting in excessive exposure to microbial antigens, recruitment of leukocytes, release of soluble mediators, and ultimately mucosal damage. An inflammatory microenvironment affects epithelial barrier properties and mucosal homeostasis by altering the structure and function of epithelial intercellular junctions through direct and indirect mechanisms. We review our current understanding of complex interactions between the intestinal epithelium and immune cells, with a focus on pathologic mucosal inflammation and mechanisms of epithelial repair. We discuss leukocyte–epithelial interactions, as well as inflammatory mediators that affect the epithelial barrier and mucosal repair. Increased knowledge of communication networks between the epithelium and immune system will lead to tissue-specific strategies for treating pathologic intestinal inflammation. PMID:27436072

  4. HELQ promotes RAD51 paralogue-dependent repair to avert germ cell loss and tumorigenesis

    DEFF Research Database (Denmark)

    Adelman, Carrie A.; Lolo, Rafal L.; Birkbak, Nicolai Juul

    2013-01-01

    helicase HELQ in ICL repair in Drosophila melanogaster (MUS301 (ref. 3)) and Caenorhabditis elegans (HELQ-1 (ref. 4)). Although in vitro analysis suggests that HELQ preferentially unwinds synthetic replication fork substrates with 3' single-stranded DNA overhangs and also disrupts protein-DNA interactions...... while translocating along DNA, little is known regarding its functions in mammalian organisms. Here we report that HELQ helicase-deficient mice exhibit subfertility, germ cell attrition, ICL sensitivity and tumour predisposition, with Helq heterozygous mice exhibiting a similar, albeit less severe...... role for HELQ in replication-coupled DNA repair, germ cell maintenance and tumour suppression in mammals....

  5. Discovery of Novel Small Molecules that Activate Satellite Cell Proliferation and Enhance Repair of Damaged Muscle.

    Science.gov (United States)

    Billin, Andrew N; Bantscheff, Marcus; Drewes, Gerard; Ghidelli-Disse, Sonja; Holt, Jason A; Kramer, Henning F; McDougal, Alan J; Smalley, Terry L; Wells, Carrow I; Zuercher, William J; Henke, Brad R

    2016-02-19

    Skeletal muscle progenitor stem cells (referred to as satellite cells) represent the primary pool of stem cells in adult skeletal muscle responsible for the generation of new skeletal muscle in response to injury. Satellite cells derived from aged muscle display a significant reduction in regenerative capacity to form functional muscle. This decrease in functional recovery has been attributed to a decrease in proliferative capacity of satellite cells. Hence, agents that enhance the proliferative abilities of satellite cells may hold promise as therapies for a variety of pathological settings, including repair of injured muscle and age- or disease-associated muscle wasting. Through phenotypic screening of isolated murine satellite cells, we identified a series of 2,4-diaminopyrimidines (e.g., 2) that increased satellite cell proliferation. Importantly, compound 2 was effective in accelerating repair of damaged skeletal muscle in an in vivo mouse model of skeletal muscle injury. While these compounds were originally prepared as c-Jun N-terminal kinase 1 (JNK-1) inhibitors, structure-activity analyses indicated JNK-1 inhibition does not correlate with satellite cell activity. Screening against a broad panel of kinases did not result in identification of an obvious molecular target, so we conducted cell-based proteomics experiments in an attempt to identify the molecular target(s) responsible for the potentiation of the satellite cell proliferation. These data provide the foundation for future efforts to design improved small molecules as potential therapeutics for muscle repair and regeneration.

  6. Effect of heat shock on poly(ADP-ribose) synthetase and DNA repair in Drosophila cells

    Energy Technology Data Exchange (ETDEWEB)

    Nolan, N.L.; Kidwell, W.R.

    1982-04-01

    Poly(ADP-ribose) synthetase, a chromatin-bound enzyme which attaches polyanionic chains of ADP-ribose to nuclear proteins, was found to be temperature sensitive in intact Drosophila melanogaster cells. The synthetase was completely inactivated by heat-shocking the cells at 37/sup 0/C for 5 min, a condition which had no appreciable effect on the subsequent growth of Drosophila cells at their physiological temperature. The heat-shock effect on synthetase was reversible; enzyme activity began to reappear about 2 hr post heat shock. During the 2-hr interval when poly(ADP-ribose) synthetase was absent, the cells were competent in repair of ..gamma..-ray-induced DNA strand breaks as shown by DNA sedimentation studies on alkaline sucrose gradients. It is thus concluded that poly(ADP-ribose) synthesis is unnecessary for repair of DNA strand breaks introduced by irradiation. The same conclusion was reached from the fact that two inhibitors of poly(ADP-ribose) synthetase 3-aminobenzamide and 5-methylnicotinamide, failed to block repair of ..gamma..-ray-induced DNA chain breaks even though both inhibitors reduced the amount of poly(ADP-ribose) synthesized in cells by 50-75%. Although it was found that the repair of DNA strand breaks is independent of poly(ADP-ribose) synthesis, irradiation does activate the synthetase in control cells, as shown by radioimmunoassay of poly(ADP-ribose) levels.

  7. Aryl hydrocarbon receptor (AhR) agonists suppress interleukin-6 expression by bone marrow stromal cells: an immunotoxicology study

    OpenAIRE

    2003-01-01

    Abstract Background Bone marrow stromal cells produce cytokines required for the normal growth and development of all eight hematopoietic cell lineages. Aberrant cytokine production by stromal cells contributes to blood cell dyscrasias. Consequently, factors that alter stromal cell cytokine production may significantly compromise the development of normal blood cells. We have shown that environmental chemicals, such as aromatic hydrocarbon receptor (AhR) agonists, suppress B lymphopoiesis by ...

  8. Telocytes as a Source of Progenitor Cells in Regeneration and Repair Through Granulation Tissue.

    Science.gov (United States)

    Díaz-Flores, Lucio; Gutiérrez, Ricardo; Pino García, Maria; González, Miriam; Díaz-Flores, Lucio; Francisco Madrid, Juan

    2016-01-01

    This review outlines the role of CD34+ stromal cells/telocytes (CD34+ SC/TCs) in repair and considers the following issues. Firstly, the conceptual aspects of repair, including regeneration and repair through granulation tissue (RTGT) as two types of repair, RTGT stages (inflammatory, proliferative, and remodeling), and tissue in repair as a substrate to assess the in vivo behavior of activated CD34+ SC/TCs. Subsequently, current knowledge of CD34+ SC/TCs, such as identification, characteristics, and functions, as well as possible stages (quiescent and activated) are taken into account. We then consider the role in regeneration of quiescent CD34+ SC/TCs (in unperturbed physiological conditions) as a nurse of stem cells (e.g., in the heart, skin, respiratory tree, gastrointestinal tract, liver, eye, and choroid plexus). Special attention is paid to the characteristics of activated CD34+ SC/TCs and the overlapping steps of activation with and without loss of CD34 expression and with and without gain of αSMA expression. With this contribution, we establish the role of CD34+ SC/TCs as progenitor cells and as a source of fibroblasts and myofibroblasts in repair through granulation tissue, fibrosis, and tumor stroma. Activated CD34+ SC/TCs in encapsulation and other processes (e.g., Reinke's edema, cutaneous myxoid cyst, mixomatous mitral valve degeneration, and fibrous papula of the face) are also outlined. Finally, similarities between modifications of CD34+ SC/TCs during in vivo activation and of multipotent mesenchymal stromal/stem cells in culture are examined in order to correlate the growing literature on CD34+ SC/TCs and the exponential research in cultured mesenchymal stromal/stem cells.

  9. Polymorphisms in human DNA repair genes and head and neck squamous cell carcinoma

    Indian Academy of Sciences (India)

    Rim Khlifi; Ahmed Rebai; Amel Hamza-Chaffai

    2012-12-01

    Genetic polymorphisms in some DNA repair proteins are associated with a number of malignant transformations like head and neck squamous cell carcinoma (HNSCC). Xeroderma pigmentosum group D (XPD) and X-ray repair cross-complementing proteins 1 (XRCC1) and 3 (XRCC3) genes are involved in DNA repair and were found to be associated with HNSCC in numerous studies. To establish our overall understanding of possible relationships between DNA repair gene polymorphisms and development of HNSCC, we surveyed the literature on epidemiological studies that assessed potential associations with HNSCC risk in terms of gene–environment interactions, genotype-induced functional defects in enzyme activity and/or protein expression, and the influence of ethnic origin on these associations.We conclude that large, well-designed studies of common polymorphisms in DNA repair genes are needed. Such studies may benefit from analysis of multiple genes or polymorphisms and from the consideration of relevant exposures that may influence the likelihood of HNSCC when DNA repair capacity is reduced.

  10. A selective aryl hydrocarbon receptor modulator 3,3'-Diindolylmethane inhibits gastric cancer cell growth

    Directory of Open Access Journals (Sweden)

    Yin Xiao-Fei

    2012-05-01

    Full Text Available Abstract Background Aryl hydrocarbon receptor (AhR is a ligand-activated transcription factor associated with gastric carcinogenesis. 3,3'-Diindolylmethane (DIM is a relatively non-toxic selective AhR modulator. This study was to detect the effects of DIM on gastric cancer cell growth. Methods Gastric cancer cell SGC7901 was treated with DIM at different concentrations (0,10,20,30,40,50 μmol/L with or without an AhR antagonist, resveratrol. The expression of AhR and Cytochrome P4501A1 (CYP1A1, a classic target gene of AhR pathway, were detected by RT-PCR and Western blot; cell viability was measured by MTT assay, and the changes in cell cycle and apoptosis were analyzed by flow cytometry. Results RT-PCR and western-blot showed that with the increase of the concentration of DIM, AhR protein gradually decreased and CYP1A1 expression increased, suggesting that DIM activated the AhR pathway and caused the translocation of AhR from cytoplasm to nucleus. MTT assay indicated that the viability of SGC7901 cells was significantly decreased in a concentration- and time-dependent manner after DIM treatment and this could be partially reversed by resveratrol. Flow cytometry analysis showed that DIM arrested cell cycle in G1 phase and induced cell apoptosis. Conclusion Selective aryl hydrocarbon receptor modulator 3,3'-Diindolylmethane inhibits SGC7901 cell proliferation by inducing apoptosis and delaying cell cycle progression. AhR may be a potential therapeutic target for gastric cancer treatment.

  11. Human amniotic epithelial cells combined with silk ifbroin scaffold in the repair of spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    Ting-gang Wang; Jie Xu; Ai-hua Zhu; Hua Lu; Zong-ning Miao; Peng Zhao; Guo-zhen Hui; Wei-jiangWu

    2016-01-01

    Treatment and functional reconstruction atfer central nervous system injury is a major medical and social challenge. An increasing number of researchers are attempting to use neural stem cells combined with artiifcial scaffold materials, such as ifbroin, for nerve repair. However, such approaches are challenged by ethical and practical issues. Amniotic tissue, a clinical waste product, is abundant, and amniotic epithe-lial cells are pluripotent, have low immunogenicity, and are not the subject of ethical debate. We hypothesized that amniotic epithelial cells combined with silk ifbroin scaffolds would be conducive to the repair of spinal cord injury. To test this, we isolated and cultured amniotic epithelial cells, and constructed complexes of these cells and silk ifbroin scaffolds. Implantation of the cell-scaffold complex into a rat model of spinal cord injury resulted in a smaller glial scar in the damaged cord tissue than in model rats that received a blank scaffold, or amniotic epithelial cells alone. In addition to a milder local immunological reaction, the rats showed less inlfammatory cell inifltration at the trans-plant site, milder host-versus-gratf reaction, and a marked improvement in motor function. hTese ifndings conifrm that the transplantation of amniotic epithelial cells combined with silk ifbroin scaffold can promote the repair of spinal cord injury. Silk ifbroin scaffold can provide a good nerve regeneration microenvironment for amniotic epithelial cells.

  12. Exposure to runoff from coal-tar-sealed pavement induces genotoxicity and impairment of DNA repair capacity in the RTL-W1 fish liver cell line

    Energy Technology Data Exchange (ETDEWEB)

    Kienzler, Aude, E-mail: aude.kienzler@entpe.fr [Université de Lyon, UMR LEHNA 5023, USC INRA, ENTPE, rue Maurice Audin, Vaulx-en-Velin F-69518 (France); Mahler, Barbara J., E-mail: bjmahler@usgs.gov [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Van Metre, Peter C., E-mail: pcvanmet@usgs.gov [U.S. Geological Survey, 1505 Ferguson Lane, Austin, TX 78754 (United States); Schweigert, Nathalie [Université de Lyon, UMR LEHNA 5023, USC INRA, ENTPE, rue Maurice Audin, Vaulx-en-Velin F-69518 (France); Devaux, Alain, E-mail: alain.devaux@entpe.fr [Université de Lyon, UMR LEHNA 5023, USC INRA, ENTPE, rue Maurice Audin, Vaulx-en-Velin F-69518 (France); Bony, Sylvie, E-mail: bony@entpe.fr [Université de Lyon, UMR LEHNA 5023, USC INRA, ENTPE, rue Maurice Audin, Vaulx-en-Velin F-69518 (France)

    2015-07-01

    Coal-tar-based (CTB) sealcoat, frequently applied to parking lots and driveways in North America, contains elevated concentrations of polycyclic aromatic hydrocarbons (PAHs) and related compounds. The RTL-W1 fish liver cell line was used to investigate two endpoints (genotoxicity and DNA-repair-capacity impairment) associated with exposure to runoff from asphalt pavement with CTB sealcoat or with an asphalt-based sealcoat hypothesized to contain about 7% CTB sealcoat (AS-blend). Genotoxic potential was assessed by the Formamido pyrimidine glycosylase (Fpg)-modified comet assay for 1:10 and 1:100 dilutions of runoff samples collected from 5 h to 36 d following sealcoat application. DNA-repair capacity was assessed by the base excision repair comet assay for 1:10 dilution of samples collected 26 h and 36 d following application. Both assays were run with and without co-exposure to ultraviolet-A radiation (UVA). With co-exposure to UVA, genotoxic effects were significant for both dilutions of CTB runoff for three of four sample times, and for some samples of AS-blend runoff. Base excision repair was significantly impaired for CTB runoff both with and without UVA exposure, and for AS-blend runoff only in the absence of UVA. This study is the first to investigate the effects of exposure to the complex mixture of chemicals in coal tar on DNA repair capacity. The results indicate that co-exposure to runoff from CT-sealcoated pavement and UVA as much as a month after sealcoat application has the potential to cause genotoxicity and impair DNA repair capacity. - Highlights: • Co-exposure to runoff from coal-tar-sealcoated pavement and UVA caused DNA damage. • Significant genotoxicity occurred with a 1:100 dilution of runoff. • Runoff collected up to 36 d following coal-tar-sealcoat application was genotoxic. • Exposure to runoff from sealed pavement impaired an important DNA repair pathway. • Repair capacity was impaired with a 1:10 dilution of runoff (1:100 not

  13. An endogenous aryl hydrocarbon receptor ligand inhibits proliferation and migration of human ovarian cancer cells.

    Science.gov (United States)

    Wang, Kai; Li, Yan; Jiang, Yi-Zhou; Dai, Cai-Feng; Patankar, Manish S; Song, Jia-Sheng; Zheng, Jing

    2013-10-28

    The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor mediates many biological processes. Herein, we investigated if 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE, an endogenous AhR ligand) regulated proliferation and migration of human ovarian cancer cells via AhR. We found that AhR was widely present in many histotypes of ovarian cancer tissues. ITE suppressed OVCAR-3 cell proliferation and SKOV-3 cell migration in vitro, which were blocked by AhR knockdown. ITE also suppressed OVCAR-3 cell growth in mice. These data suggest that the ITE might potentially be used for therapeutic intervention for at least a subset of human ovarian cancer.

  14. Potential of cardiac stem/progenitor cells and induced pluripotent stem cells for cardiac repair in ischaemic heart disease.

    Science.gov (United States)

    Wang, Wei Eric; Chen, Xiongwen; Houser, Steven R; Zeng, Chunyu

    2013-10-01

    Stem cell therapy has emerged as a promising strategy for cardiac and vascular repair. The ultimate goal is to rebuild functional myocardium by transplanting exogenous stem cells or by activating native stem cells to induce endogenous repair. CS/PCs (cardiac stem/progenitor cells) are one type of adult stem cell with the potential to differentiate into cardiac lineages (cardiomyocytes, smooth muscle cells and endothelial cells). iPSCs (induced pluripotent stem cells) also have the capacity to differentiate into necessary cells to rebuild injured cardiac tissue. Both types of stem cells have brought promise for cardiac repair. The present review summarizes recent advances in cardiac cell therapy based on these two cell sources and discusses the advantages and limitations of each candidate. We conclude that, although both types of stem cells can be considered for autologous transplantation with promising outcomes in animal models, CS/PCs have advanced more in their clinical application because iPSCs and their derivatives possess inherent obstacles for clinical use. Further studies are needed to move cell therapy forward for the treatment of heart disease.

  15. Base excision repair activities differ in human lung cancer cells and corresponding normal controls

    DEFF Research Database (Denmark)

    Karahalil, Bensu; Bohr, Vilhelm A; De Souza-Pinto, Nadja C

    2010-01-01

    Oxidative damage to DNA is thought to play a role in carcinogenesis by causing mutations, and indeed accumulation of oxidized DNA bases has been observed in samples obtained from tumors but not from surrounding tissue within the same patient. Base excision repair (BER) is the main pathway...... for the repair of oxidized modifications both in nuclear and mitochondrial DNA. In order to ascertain whether diminished BER capacity might account for increased levels of oxidative DNA damage in cancer cells, the activities of BER enzymes in three different lung cancer cell lines and their non......-cancerous counterparts were measured using oligonucleotide substrates with single DNA lesions to assess specific BER enzymes. The activities of four BER enzymes, OGG1, NTH1, UDG and APE1, were compared in mitochondrial and nuclear extracts. For each specific lesion, the repair activities were similar among the three...

  16. Distinctions in sensitivity and repair of cells of children with some hereditary diseases

    Energy Technology Data Exchange (ETDEWEB)

    Zasukhina, G.D.; Barashnev, Yu.I.; Vasil' eva, I.M.; Sdirkova, N.I.; Semyachkina, A.N. (AN SSSR, Moscow. Inst. Obshchej Genetiki)

    A study was made of blood cell sensitivity of children with some hereditary diseases, to ..gamma..-radiation and 4-nitro-quinoline-1-oxide. Using the host cell reactivation and chromatographic methods we revealed the increase in the sensitivity to the above mentioned agents and inhibition of the repair function in cells of patients with the following diseases: Marfan's disease, histidinemia, osteogenesis imperfecta, Sylvere-Russelle, Laurence, Franchescetti, and Losch-Nychane syndromes.

  17. Fluorometric analysis of the formation and repair of DNA breaks in irradiated cells

    Energy Technology Data Exchange (ETDEWEB)

    Ryabchenko, N.I.; Proskuryakov, S.Ya.; Ivannik, B.P.; Kutmin, A.I. (Akademiya Meditsinskikh Nauk SSSR, Obninsk. Nauchno-Issledovatel' skij Inst. Meditsinskoj Radiologii)

    A study was made of the dependence of the fluorescence of ethidium bromide upon NaOH concentration after staining of single- and double-strand DNA in cell lysates was demonstrated. The method of fluorometry was used to study the dose dependence of a change in the share of double-stranded DNA in the irradiated thymocytes and Ehrlich ascites carcinoma cells which permitted to determine the appearance and repair of DNA breaks in these cells.

  18. Uninduced adipose-derived stem cells repair the defect of full-thickness hyaline cartilage.

    Science.gov (United States)

    Zhang, Hai-Ning; Li, Lei; Leng, Ping; Wang, Ying-Zhen; Lv, Cheng-Yu

    2009-04-01

    To testify the effect of the stem cells derived from the widely distributed fat tissue on repairing full-thickness hyaline cartilage defects. Adipose-derived stem cells (ADSCs) were derived from adipose tissue and cultured in vitro. Twenty-seven New Zealand white rabbits were divided into three groups randomly. The cultured ADSCs mixed with calcium alginate gel were used to fill the full-thickness hyaline cartilage defects created at the patellafemoral joint, and the defects repaired with gel or without treatment served as control groups. After 4, 8 and 12 weeks, the reconstructed tissue was evaluated macroscopically and microscopically. Histological analysis and qualitative scoring were also performed to detect the outcome. Full thickness hyaline cartilage defects were repaired completely with ADSCs-derived tissue. The result was better in ADSCs group than the control ones. The microstructure of reconstructed tissue with ADSCs was similar to that of hyaline cartilage and contained more cells and regular matrix fibers, being better than other groups. Plenty of collagen fibers around cells could be seen under transmission electron microscopy. Statistical analysis revealed a significant difference in comparison with other groups at each time point (t equal to 4.360, P less than 0.01). These results indicate that stem cells derived from mature adipose without induction possess the ability to repair cartilage defects.

  19. Uninduced adipose-derived stem cells repair the defect of full-thickness hyaline cartilage

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-ning; LI Lei; LENG Ping; WANG Ying-zhen; Lü Cheng-yu

    2009-01-01

    Objective: To testify the effect of the stem cells derived from the widely distributed fat tissue on repairing full-thickness hyaline cartilage defects.Methods: Adipose-derived stem cells (ADSCs) were derived from adipose tissue and cultured in vitro.Twentyseven New Zealand white rabbits were divided into three groups randomly.The cultured ADSCs mixed with calcium alginate gel were used to fill the full-thickness hyaline cartilage defects created at the patellafemoral joint,and the defects repaired with gel or without treatment served as control groups.After 4,8 and 12 weeks,the reconstructed tissue was evaluated macroscopically and microscopically.Histological analysis and qualitative scoring were also performed to detect the outcome.Results: Full thickness hyaline cartilage defects were repaired completely with ADSCs-derived dssue.The result was better in ADSCs group than the control ones.The microstructure of reconstructed tissue with ADSCs was similar to that of hvaline cartilage and contained more cells and regular matrix fibers,being better than other groups.Plenty of collagen fibers around cells could be seen under transmission electron microscopy.Statistical analysis revealed a significant difference in comparison with other groups at each time point(t=4.360,P<0.01).Conclusion: Thcse results indicate that stem cells derived from mature adipose without induction possess the ability to repair cartilage defects

  20. Heterogeneous Stem Cells in Skin Homeostatis and Wound Repair

    OpenAIRE

    Anna Meilana; Nurrani Mustika Dewi; Andi Wijaya

    2015-01-01

    BACKGROUND: The skin protects mammals from insults, infection and dehydration and enables thermoregulation and sensory perception. Various skin-resident cells carry out these diverse functions. Constant turnover of cells and healing upon injury necessitate multiple reservoirs of stem cells. The skin is a complex organ harboring several distinct populations of stem cells and a rich array of cell types. Advances in genetic and imaging tools have brought new findings about the lineage relationsh...

  1. Cell- and gene-therapy approaches to inner ear repair

    OpenAIRE

    Conde de Felipe, Magnolia; Feijoo-Redondo, Ana; García-Sancho, Javier; Schimmang, Thomas; Durán, Mercedes

    2011-01-01

    Sensorineural hearing loss is the most common sensory disorder in humans. It is primarily due to the degeneration of highly specialised mechanosensory cells in the cochlea, the so-called hair cells. Hearing problems can also be caused or further aggravated by the death of auditory sensory neurons that convey the information from the hair cells to the brain stem. Despite the discovery of stem/progenitor cells in the mammalian cochlea, no regeneration of either damaged hair cells or auditory ne...

  2. Types, Causes, Detection and Repair of DNA Fragmentation in Animal and Human Sperm Cells

    Directory of Open Access Journals (Sweden)

    Rosa Roy

    2012-10-01

    Full Text Available Concentration, motility and morphology are parameters commonly used to determine the fertilization potential of an ejaculate. These parameters give a general view on the quality of sperm but do not provide information about one of the most important components of the reproductive outcome: DNA. Either single or double DNA strand breaks can set the difference between fertile and infertile males. Sperm DNA fragmentation can be caused by intrinsic factors like abortive apoptosis, deficiencies in recombination, protamine imbalances or oxidative stress. Damage can also occur due to extrinsic factors such as storage temperatures, extenders, handling conditions, time after ejaculation, infections and reaction to medicines or post-testicular oxidative stress, among others. Two singular characteristics differentiate sperm from somatic cells: Protamination and absence of DNA repair. DNA repair in sperm is terminated as transcription and translation stops post-spermiogenesis, so these cells have no mechanism to repair the damage occurred during their transit through the epididymis and post-ejaculation. Oocytes and early embryos have been shown to repair sperm DNA damage, so the effect of sperm DNA fragmentation depends on the combined effects of sperm chromatin damage and the capacity of the oocyte to repair it. In this contribution we review some of these issues.

  3. Types, Causes, Detection and Repair of DNA Fragmentation in Animal and Human Sperm Cells

    Science.gov (United States)

    González-Marín, Clara; Gosálvez, Jaime; Roy, Rosa

    2012-01-01

    Concentration, motility and morphology are parameters commonly used to determine the fertilization potential of an ejaculate. These parameters give a general view on the quality of sperm but do not provide information about one of the most important components of the reproductive outcome: DNA. Either single or double DNA strand breaks can set the difference between fertile and infertile males. Sperm DNA fragmentation can be caused by intrinsic factors like abortive apoptosis, deficiencies in recombination, protamine imbalances or oxidative stress. Damage can also occur due to extrinsic factors such as storage temperatures, extenders, handling conditions, time after ejaculation, infections and reaction to medicines or post-testicular oxidative stress, among others. Two singular characteristics differentiate sperm from somatic cells: Protamination and absence of DNA repair. DNA repair in sperm is terminated as transcription and translation stops post-spermiogenesis, so these cells have no mechanism to repair the damage occurred during their transit through the epididymis and post-ejaculation. Oocytes and early embryos have been shown to repair sperm DNA damage, so the effect of sperm DNA fragmentation depends on the combined effects of sperm chromatin damage and the capacity of the oocyte to repair it. In this contribution we review some of these issues. PMID:23203048

  4. Hypothermia postpones DNA damage repair in irradiated cells and protects against cell killing

    Energy Technology Data Exchange (ETDEWEB)

    Baird, Brandon J.; Dickey, Jennifer S.; Nakamura, Asako J.; Redon, Christophe E.; Parekh, Palak [Laboratory of Molecular Pharmacology, CCR, NCI, Bethesda, MD 20892 (United States); Griko, Yuri V. [Radiation and Space Biotechnology Branch, NASA Ames Research Center, Moffett Field, CA 94035 (United States); Aziz, Khaled; Georgakilas, Alexandros G. [Biology Department, East Carolina University, Greenville, NC 27858 (United States); Bonner, William M. [Laboratory of Molecular Pharmacology, CCR, NCI, Bethesda, MD 20892 (United States); Martin, Olga A., E-mail: sedelnio@mail.nih.gov [Laboratory of Molecular Pharmacology, CCR, NCI, Bethesda, MD 20892 (United States)

    2011-06-03

    Hibernation is an established strategy used by some homeothermic organisms to survive cold environments. In true hibernation, the core body temperature of an animal may drop to below 0 {sup o}C and metabolic activity almost cease. The phenomenon of hibernation in humans is receiving renewed interest since several cases of victims exhibiting core body temperatures as low as 13.7 {sup o}C have been revived with minimal lasting deficits. In addition, local cooling during radiotherapy has resulted in normal tissue protection. The experiments described in this paper were prompted by the results of a very limited pilot study, which showed a suppressed DNA repair response of mouse lymphocytes collected from animals subjected to 7-Gy total body irradiation under hypothermic (13 {sup o}C) conditions, compared to normothermic controls. Here we report that human BJ-hTERT cells exhibited a pronounced radioprotective effect on clonogenic survival when cooled to 13 {sup o}C during and 12 h after irradiation. Mild hypothermia at 20 and 30 {sup o}C also resulted in some radioprotection. The neutral comet assay revealed an apparent lack on double strand break (DSB) rejoining at 13 {sup o}C. Extension of the mouse lymphocyte study to ex vivo-irradiated human lymphocytes confirmed lower levels of induced phosphorylated H2AX ({gamma}-H2AX) and persistence of the lesions at hypothermia compared to the normal temperature. Parallel studies of radiation-induced oxidatively clustered DNA lesions (OCDLs) revealed partial repair at 13 {sup o}C compared to the rapid repair at 37 {sup o}C. For both {gamma}-H2AX foci and OCDLs, the return of lymphocytes to 37 {sup o}C resulted in the resumption of normal repair kinetics. These results, as well as observations made by others and reviewed in this study, have implications for understanding the radiobiology and protective mechanisms underlying hypothermia and potential opportunities for exploitation in terms of protecting normal tissues against

  5. Signalling pathways that inhibit the capacity of precursor cells for myelin repair.

    Science.gov (United States)

    Sabo, Jennifer K; Cate, Holly S

    2013-01-07

    In demyelinating disorders such as Multiple Sclerosis (MS), targets of injury are myelin and oligodendrocytes, leading to severe neurological dysfunction. Regenerative therapies aimed at promoting oligodendrocyte maturation and remyelination are promising strategies for treatment in demyelinating disorders. Endogenous precursor cells or exogenous transplanted cells are potential sources for remyelinating oligodendrocytes in the central nervous system (CNS). Several signalling pathways have been implicated in regulating the capacity of these cell populations for myelin repair. Here, we review neural precursor cells and oligodendrocyte progenitor cells as potential sources for remyelinating oligodendrocytes and evidence for the functional role of key signalling pathways in inhibiting regeneration from these precursor cell populations.

  6. Signalling Pathways that Inhibit the Capacity of Precursor Cells for Myelin Repair

    Directory of Open Access Journals (Sweden)

    Jennifer K. Sabo

    2013-01-01

    Full Text Available In demyelinating disorders such as Multiple Sclerosis (MS, targets of injury are myelin and oligodendrocytes, leading to severe neurological dysfunction. Regenerative therapies aimed at promoting oligodendrocyte maturation and remyelination are promising strategies for treatment in demyelinating disorders. Endogenous precursor cells or exogenous transplanted cells are potential sources for remyelinating oligodendrocytes in the central nervous system (CNS. Several signalling pathways have been implicated in regulating the capacity of these cell populations for myelin repair. Here, we review neural precursor cells and oligodendrocyte progenitor cells as potential sources for remyelinating oligodendrocytes and evidence for the functional role of key signalling pathways in inhibiting regeneration from these precursor cell populations.

  7. The Role of Cell Plasticity in Tissue Repair: Adaptive Cellular Reprogramming.

    Science.gov (United States)

    Jessen, Kristjan R; Mirsky, Rhona; Arthur-Farraj, Peter

    2015-09-28

    It is becoming clear that a radical change of cell identity of differentiated cells in vivo, triggered by injury or other adversity, provides an essential route to recovery for many different mammalian tissues. This process, which we term adaptive cellular reprogramming, promotes regeneration in one of two ways: by providing a transient class of repair cells or by directly replacing cells lost during tissue damage. Controlling adaptive changes in cell fate in vivo in order to promote the body's own cell therapy, particularly by pharmacology rather than genetics, is likely to become an increasingly active area of future work. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Hydrocarbon pneumonia

    Science.gov (United States)

    Pneumonia - hydrocarbon ... Coughing Fever Shortness of breath Smell of a hydrocarbon product on the breath Stupor (decreased level of ... Most children who drink or inhale hydrocarbon products and develop ... hydrocarbons may lead to rapid respiratory failure and death.

  9. Alteration in cell surface properties of Burkholderia spp. during surfactant-aided biodegradation of petroleum hydrocarbons

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Sagarika; Mukherji, Suparna [Indian Institute of Technology Bombay, Mumbai (India). Centre for Environmental Science and Engineering (CESE)

    2012-04-15

    Chemical surfactants may impact microbial cell surface properties, i.e., cell surface hydrophobicity (CSH) and cell surface charge, and may thus affect the uptake of components from non-aqueous phase liquids (NAPLs). This work explored the impact of Triton X-100, Igepal CA 630, and Tween 80 (at twice the critical micelle concentration, CMC) on the cell surface characteristics of Burkholderia cultures, Burkholderia cepacia (ES1, aliphatic degrader) and Burkholderia multivorans (NG1, aromatic degrader), when grown on a six-component model NAPL. In the presence of Triton X-100, NAPL biodegradation was enhanced from 21% to 60% in B. cepacia and from 18% to 53% in B. multivorans. CSH based on water contact angle (50-52 ) was in the same range for both strains while zeta potential at neutral pH was -38 and -31 mV for B. cepacia and B. multivorans, respectively. In the presence of Triton X-100, their CSH increased to greater than 75 and the zeta potential decreased. This induced a change in the mode of uptake and initiated aliphatic hydrocarbon degradation by B. multivorans and increased the rate of aliphatic hydrocarbon degradation in B. cepacia. Igepal CA 630 and Tween 80 also altered the cell surface properties. For B. cepacia grown in the presence of Triton X-100 at two and five times its CMC, CSH increased significantly in the log growth phase. Growth in the presence of the chemical surfactants also affected the abundance of chemical functional groups on the cell surface. Cell surface changes had maximum impact on NAPL degradation in the presence of emulsifying surfactants, Triton X-100 and Igepal CA630.

  10. Repair of Ischemic Injury by Pluripotent Stem Cell Based Cell Therapy without Teratoma through Selective Photosensitivity.

    Science.gov (United States)

    Cho, Seung-Ju; Kim, So-Yeon; Jeong, Ho-Chang; Cheong, Hyeonsik; Kim, Doseok; Park, Soon-Jung; Choi, Jong-Jin; Kim, Hyongbum; Chung, Hyung-Min; Moon, Sung-Hwan; Cha, Hyuk-Jin

    2015-12-01

    Stem-toxic small molecules have been developed to induce selective cell death of pluripotent stem cells (PSCs) to lower the risk of teratoma formation. However, despite their high efficacies, chemical-based approaches may carry unexpected toxicities on specific differentiated cell types. Herein, we took advantage of KillerRed (KR) as a suicide gene, to selectively induce phototoxicity using visible light via the production of reactive oxygen species. PSCs in an undifferentiated state that exclusively expressed KR (KR-PSCs) were eliminated by a single exposure to visible light. This highly selective cell death in KR-PSCs was exploited to successfully inhibit teratoma formation. In particular, endothelial cells from KR-mPSCs remained fully functional in vitro and sufficient to repair ischemic injury in vivo regardless of light exposure, suggesting that a genetic approach in which KR is expressed in a tightly controlled manner would be a viable strategy to inhibit teratoma formation for future safe PSC-based therapies.

  11. Repair of Ischemic Injury by Pluripotent Stem Cell Based Cell Therapy without Teratoma through Selective Photosensitivity

    Directory of Open Access Journals (Sweden)

    Seung-Ju Cho

    2015-12-01

    Full Text Available Stem-toxic small molecules have been developed to induce selective cell death of pluripotent stem cells (PSCs to lower the risk of teratoma formation. However, despite their high efficacies, chemical-based approaches may carry unexpected toxicities on specific differentiated cell types. Herein, we took advantage of KillerRed (KR as a suicide gene, to selectively induce phototoxicity using visible light via the production of reactive oxygen species. PSCs in an undifferentiated state that exclusively expressed KR (KR-PSCs were eliminated by a single exposure to visible light. This highly selective cell death in KR-PSCs was exploited to successfully inhibit teratoma formation. In particular, endothelial cells from KR-mPSCs remained fully functional in vitro and sufficient to repair ischemic injury in vivo regardless of light exposure, suggesting that a genetic approach in which KR is expressed in a tightly controlled manner would be a viable strategy to inhibit teratoma formation for future safe PSC-based therapies.

  12. Propofol promotes spinal cord injury repair by bone marrow mesenchymal stem cell transplantation

    Directory of Open Access Journals (Sweden)

    Ya-jing Zhou

    2015-01-01

    Full Text Available Propofol is a neuroprotective anesthetic. Whether propofol can promote spinal cord injury repair by bone marrow mesenchymal stem cells remains poorly understood. We used rats to investigate spinal cord injury repair using bone marrow mesenchymal stem cell transplantation combined with propofol administration via the tail vein. Rat spinal cord injury was clearly alleviated; a large number of newborn non-myelinated and myelinated nerve fibers appeared in the spinal cord, the numbers of CM-Dil-labeled bone marrow mesenchymal stem cells and fluorogold-labeled nerve fibers were increased and hindlimb motor function of spinal cord-injured rats was markedly improved. These improvements were more prominent in rats subjected to bone marrow mesenchymal cell transplantation combined with propofol administration than in rats receiving monotherapy. These results indicate that propofol can enhance the therapeutic effects of bone marrow mesenchymal stem cell transplantation on spinal cord injury in rats.

  13. Propofol promotes spinal cord injury repair by bone marrow mesenchymal stem cell transplantation

    Institute of Scientific and Technical Information of China (English)

    Ya-jing Zhou; Jian-min Liu; Shu-ming Wei; Yun-hao Zhang; Zhen-hua Qu; Shu-bo Chen

    2015-01-01

    Propofol is a neuroprotective anesthetic. Whether propofol can promote spinal cord injury repair by bone marrow mesenchymal stem cells remains poorly understood. We used rats to investigate spinal cord injury repair using bone marrow mesenchymal stem cell transplantation combined with propofol administrationvia the tail vein. Rat spinal cord injury was clearly alleviated; a large number of newborn non-myelinated and myelinated nerve ifbers appeared in the spinal cord, the numbers of CM-Dil-labeled bone marrow mesenchymal stem cells and lfuorogold-labeled nerve ifbers were increased and hindlimb motor function of spinal cord-injured rats was mark-edly improved. These improvements were more prominent in rats subjected to bone marrow mesenchymal cell transplantation combined with propofol administration than in rats receiving monotherapy. These results indicate that propofol can enhance the therapeutic effects of bone marrow mesenchymal stem cell transplantation on spinal cord injury in rats.

  14. Future dentistry: cell therapy meets tooth and periodontal repair and regeneration.

    Science.gov (United States)

    Catón, Javier; Bostanci, Nagihan; Remboutsika, Eumorphia; De Bari, Cosimo; Mitsiadis, Thimios A

    2011-05-01

    Cell-based tissue repair of the tooth and - tooth-supporting - periodontal ligament (PDL) is a new attractive approach that complements traditional restorative or surgical techniques for replacement of injured or pathologically damaged tissues. In such therapeutic approaches, stem cells and/or progenitor cells are manipulated in vitro and administered to patients as living and dynamic biological agents. In this review, we discuss the clonogenic potential of human dental and periodontal tissues such as the dental pulp and the PDL and their potential for tooth and periodontal repair and/or regeneration. We propose novel therapeutic approaches using stem cells or progenitor cells, which are targeted to regenerate the lost dental or periodontal tissue.

  15. The radioresistance kinase TLK1B protects the cells by promoting repair of double strand breaks

    Directory of Open Access Journals (Sweden)

    De Benedetti Arrigo

    2005-09-01

    Full Text Available Abstract Background The mammalian protein kinase TLK1 is a homologue of Tousled, a gene involved in flower development in Arabidopsis thaliana. The function of TLK1 is not well known, although knockout of the gene in Drosophila or expression of a dominant negative mutant in mouse cells causes loss of nuclear divisions and missegregation of chromosomes probably, due to alterations in chromatin remodeling capacity. Overexpression of TLK1B, a spliced variant of the TLK1 mRNA, in a model mouse cell line increases it's resistance to ionizing radiation (IR or the radiomimetic drug doxorubicin, also likely due to changes in chromatin remodeling. TLK1B is translationally regulated by the availability of the translation factor eIF4E, and its synthesis is activated by IR. The reason for this mechanism of regulation is likely to provide a rapid means of promoting repair of DSBs. TLK1B specifically phosphorylates histone H3 and Asf1, likely resulting in changes in chromatin structure, particularly at double strand breaks (DSB sites. Results In this work, we provide several lines of evidence that TLK1B protects the cells from IR by facilitating the repair of DSBs. First, the pattern of phosphorylation and dephosphorylation of H2AX and H3 indicated that cells overexpressing TLK1B return to pre-IR steady state much more rapidly than controls. Second, the repair of episomes damaged with DSBs was much more rapid in cells overexpressing TLK1B. This was also true for repair of genomic damage. Lastly, we demonstrate with an in vitro repair system that the addition of recombinant TLK1B promotes repair of a linearized plasmid incubated with nuclear extract. In addition, TLK1B in this in vitro system promotes the assembly of chromatin as shown by the formation of more highly supercoiled topomers of the plasmid. Conclusion In this work, we provide evidence that TLK1B promotes the repair of DSBs, likely as a consequence of a change in chromatin remodeling capacity that

  16. Nucleotide excision repair in intact cells contrasts with high dual incision activity in vitro

    NARCIS (Netherlands)

    Jansen, J.; Olsen, A.K.; Wiger, R.; Naegeli, H.; Boer, de P.; Hoeven, van der F.; Holme, J.A.; Brunborg, G.; Mullenders, L.

    2001-01-01

    The acquisition of genotoxin-induced mutations in the mammalian germline is detrimental to the stable transfer of genomic information. In somatic cells, nucleotide excision repair (NER) is a major pathway to counteract the mutagenic effects of DNA damage. Two NER subpathways have been identified, gl

  17. Noncanonical mismatch repair as a source of genomic instability in human cells

    DEFF Research Database (Denmark)

    Pena Diaz, Javier; Bregenhorn, Stephanie; Ghodgaonkar, Medini;

    2012-01-01

    Mismatch repair (MMR) is a key antimutagenic process that increases the fidelity of DNA replication and recombination. Yet genetic experiments showed that MMR is required for antibody maturation, a process during which the immunoglobulin loci of antigen-stimulated B cells undergo extensive mutage...

  18. The cell-cycle checkpoint kinase Chk1 is required for mammalian homologous recombination repair

    DEFF Research Database (Denmark)

    Sørensen, Claus Storgaard; Hansen, Lasse Tengbjerg; Dziegielewski, Jaroslaw

    2005-01-01

    The essential checkpoint kinase Chk1 is required for cell-cycle delays after DNA damage or blocked DNA replication. However, it is unclear whether Chk1 is involved in the repair of damaged DNA. Here we establish that Chk1 is a key regulator of genome maintenance by the homologous recombination...

  19. DNA double strand breaks repair pathways in mouse male germ cells

    NARCIS (Netherlands)

    Ahmed, E.A.

    2009-01-01

    DNA double strand breaks (DSBs) are induced by ionizing radiation, and during meiotic recombination. DSBs are repaired via two main pathways, homologous recombination (HR) and non homologous end-joining (NHEJ). There are three main types of male germ cells, spermatogonia, spermatocytes and spermatid

  20. Role of endogenous Schwann cells in tissue repair after spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    Shu-xin Zhang; Fengfa Huang; Mary Gates; Eric G. Holmberg

    2013-01-01

    Schwann cells are glial cells of peripheral nervous system, responsible for axonal myelination and ensheathing, as well as tissue repair following a peripheral nervous system injury. They are one of several cell types that are widely studied and most commonly used for cell transplantation to treat spinal cord injury, due to their intrinsic characteristics including the ability to secrete a variety of neurotrophic factors. This mini review summarizes the recent findings of endogenous Schwann cells after spinal cord injury and discusses their role in tissue repair and axonal regeneration. After spinal cord injury, numerous endogenous Schwann cells migrate into the lesion site from the nerve roots, involving in the construction of newly formed repaired tissue and axonal myelination. These invading Schwann cells also can move a long distance away from the injury site both rostrally and caudally. In addition, Schwann cells can be induced to migrate by minimal insults (such as scar ablation) within the spinal cord and integrate with astrocytes under certain circumstances. More importantly, the host Schwann cells can be induced to migrate into spinal cord by transplantation of different cell types, such as exogenous Schwann cells, olfactory ensheathing cells, and bone marrow-derived stromal stem cells. Migration of endogenous Schwann cells following spinal cord injury is a common natural phenomenon found both in animal and human, and the myelination by Schwann cells has been examined effective in signal conduction electrophysiologically. Therefore, if the inherent properties of endogenous Schwann cells could be developed and utilized, it would offer a new avenue for the restoration of injured spinal cord.

  1. Circulating osteogenic cells: implications for injury, repair, and regeneration

    DEFF Research Database (Denmark)

    Pignolo, Robert J; Kassem, Moustapha

    2011-01-01

    The aim of this review is to provide a critical reading of recent literature pertaining to the presence of circulating, fluid-phase osteoblastic cells and their possible contribution to bone formation. We have termed this group of cells collectively as circulating osteogenic precursor (COP) cells...

  2. Potential of human dental stem cells in repairing the complete transection of rat spinal cord

    Science.gov (United States)

    Yang, Chao; Li, Xinghan; Sun, Liang; Guo, Weihua; Tian, Weidong

    2017-04-01

    Objective. The adult spinal cord of mammals contains a certain amount of neural precursor cells, but these endogenous cells have a limited capacity for replacement of lost cells after spinal cord injury. The exogenous stem cells transplantation has become a therapeutic strategy for spinal cord repairing because of their immunomodulatory and differentiation capacity. In addition, dental stem cells originating from the cranial neural crest might be candidate cell sources for neural engineering. Approach. Human dental follicle stem cells (DFSCs), stem cells from apical papilla (SCAPs) and dental pulp stem cells (DPSCs) were isolated and identified in vitro, then green GFP-labeled stem cells with pellets were transplanted into completely transected spinal cord. The functional recovery of rats and multiple neuro-regenerative mechanisms were explored. Main results. The dental stem cells, especially DFSCs, demonstrated the potential in repairing the completely transected spinal cord and promote functional recovery after injury. The major involved mechanisms were speculated below: First, dental stem cells inhibited the expression of interleukin-1β to reduce the inflammatory response; second, they inhibited the expression of ras homolog gene family member A (RhoA) to promote neurite regeneration; third, they inhibited the sulfonylurea receptor1 (SUR-1) expression to reduce progressive hemorrhagic necrosis; lastly, parts of the transplanted cells survived and differentiated into mature neurons and oligodendrocytes but not astrocyte, which is beneficial for promoting axons growth. Significance. Dental stem cells presented remarkable tissue regenerative capability after spinal cord injury through immunomodulatory, differentiation and protection capacity.

  3. Efficacy of a mesenchymal stem cell loaded surgical mesh for tendon repair in rats

    OpenAIRE

    Schon, Lew C.; Gill, Nicholas; Thorpe, Margaret; Davis, Joel; Nadaud, Joshua; Kim, Jooyoung; Molligan, Jeremy; Zhang, Zijun

    2014-01-01

    Objectives The purpose of this study was to investigate the efficacy of a composite surgical mesh for delivery of mesenchymal stem cells (MSCs) in tendon repair. Methods The MSC-loaded mesh composed of a piece of conventional surgical mesh and a layer of scaffold, which supported MSC-embedded alginate gel. A 3-mm defect was surgically created at the Achilles tendon-gastrocnemius/soleus junction in 30 rats. The tendon defects were repaired with either 1) MSC-loaded mesh; or 2) surgical mesh on...

  4. Presence of base excision repair enzymes in the wheat aleurone and their activation in cells undergoing programmed cell death.

    Science.gov (United States)

    Bissenbaev, Amangeldy K; Ishchenko, Alexander A; Taipakova, Sabira M; Saparbaev, Murat K

    2011-10-01

    Cereal aleurone cells are specialized endosperm cells that produce enzymes to hydrolyze the starchy endosperm during germination. Aleurone cells can undergo programmed cell death (PCD) when incubated in the presence of gibberellic acid (GA) in contrast to abscisic acid (ABA) which inhibits the process. The progression of PCD in aleurone layer cells of wheat grain is accompanied by an increase in deoxyribonuclease (DNase) activities and the internucleosomal degradation of nuclear DNA. Reactive oxygen species (ROS) are increased during PCD in the aleurone cells owing to the β-oxidation of triglycerides and inhibition of the antioxidant enzymes possibly leading to extensive oxidative damage to DNA. ROS generate mainly non-bulky DNA base lesions which are removed in the base excision repair (BER) pathway, initiated by the DNA glycosylases. At present, very little is known about oxidative DNA damage repair in cereals. Here, we study DNA repair in the cell-free extracts of wheat aleurone layer incubated or not with phytohormones. We show, for the first time, the presence of 8-oxoguanine-DNA and ethenoadenine-DNA glycosylase activities in wheat aleurone cells. Interestingly, the DNA glycosylase and AP endonuclease activities are strongly induced in the presence of GA. Based on these data we propose that GA in addition to activation of nuclear DNases also induces the DNA repair activities which remove oxidized DNA bases in the BER pathway. Potential roles of the wheat DNA glycosylases in GA-induced oligonucleosomal fragmentation of DNA and metabolic activation of aleurone layer cells via repair of transcribed regions are discussed.

  5. Current Stem Cell Delivery Methods for Myocardial Repair

    Directory of Open Access Journals (Sweden)

    Calvin C. Sheng

    2013-01-01

    Full Text Available Heart failure commonly results from an irreparable damage due to cardiovascular diseases (CVDs, the leading cause of morbidity and mortality in the United States. In recent years, the rapid advancements in stem cell research have garnered much praise for paving the way to novel therapies in reversing myocardial injuries. Cell types currently investigated for cellular delivery include embryonic stem cells (ESCs, induced pluripotent stem cells (iPSCs, and adult stem cell lineages such as skeletal myoblasts, bone-marrow-derived stem cells (BMSCs, mesenchymal stem cells (MSCs, and cardiac stem cells (CSCs. To engraft these cells into patients’ damaged myocardium, a variety of approaches (intramyocardial, transendocardial, transcoronary, venous, intravenous, intracoronary artery and retrograde venous administrations and bioengineered tissue transplantation have been developed and explored. In this paper, we will discuss the pros and cons of these delivery modalities, the current state of their therapeutic potentials, and a multifaceted evaluation of their reported clinical feasibility, safety, and efficacy. While the issues of optimal delivery approach, the best progenitor stem cell type, the most effective dose, and timing of administration remain to be addressed, we are highly optimistic that stem cell therapy will provide a clinically viable option for myocardial regeneration.

  6. Current stem cell delivery methods for myocardial repair.

    Science.gov (United States)

    Sheng, Calvin C; Zhou, Li; Hao, Jijun

    2013-01-01

    Heart failure commonly results from an irreparable damage due to cardiovascular diseases (CVDs), the leading cause of morbidity and mortality in the United States. In recent years, the rapid advancements in stem cell research have garnered much praise for paving the way to novel therapies in reversing myocardial injuries. Cell types currently investigated for cellular delivery include embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and adult stem cell lineages such as skeletal myoblasts, bone-marrow-derived stem cells (BMSCs), mesenchymal stem cells (MSCs), and cardiac stem cells (CSCs). To engraft these cells into patients' damaged myocardium, a variety of approaches (intramyocardial, transendocardial, transcoronary, venous, intravenous, intracoronary artery and retrograde venous administrations and bioengineered tissue transplantation) have been developed and explored. In this paper, we will discuss the pros and cons of these delivery modalities, the current state of their therapeutic potentials, and a multifaceted evaluation of their reported clinical feasibility, safety, and efficacy. While the issues of optimal delivery approach, the best progenitor stem cell type, the most effective dose, and timing of administration remain to be addressed, we are highly optimistic that stem cell therapy will provide a clinically viable option for myocardial regeneration.

  7. Cell-based and biomaterial approaches to connective tissue repair

    Science.gov (United States)

    Stalling, Simone Suzette

    Connective tissue injuries of skin, tendon and ligament, heal by a reparative process in adults, filling the wound site with fibrotic, disorganized scar tissue that poorly reflects normal tissue architecture or function. Conversely, fetal skin and tendon have been shown to heal scarlessly. Complete regeneration is not intrinsically ubiquitous to all fetal tissues; fetal diaphragmatic and gastrointestinal injuries form scars. In vivo studies suggest that the presence of fetal fibroblasts is essential for scarless healing. In the orthopaedic setting, adult anterior cruciate ligament (ACL) heals poorly; however, little is known about the regenerative capacity of fetal ACL or fetal ACL fibroblasts. We characterized in vitro wound healing properties of fetal and adult ACL fibroblasts demonstrating that fetal ACL fibroblasts migrate faster and elaborate greater quantities of type I collagen, suggesting the healing potential of the fetal ACL may not be intrinsically poor. Similar to fetal ACL fibroblasts, fetal dermal fibroblasts also exhibit robust cellular properties. We investigated the age-dependent effects of dermal fibroblasts on tendon-to-bone healing in rat supraspinatus tendon injuries, a reparative injury model. We hypothesized delivery of fetal dermal fibroblasts would increase tissue organization and mechanical properties in comparison to adult dermal fibroblasts. However, at 1 and 8 weeks, the presence of dermal fibroblasts, either adult or fetal, had no significant effect on tissue histology or mechanical properties. There was a decreasing trend in cross-sectional area of repaired tendons treated with fetal dermal fibroblasts in comparison to adult, but this finding was not significant in comparison to controls. Finally, we synthesized a novel polysaccharide, methacrylated methylcellulose (MA-MC), and fabricated hydrogels using a well-established photopolymerization technique. We characterized the physical and mechanical properties of MA-MC hydrogels in

  8. Dexamethasone inhibits repair of human airway epithelial cells mediated by glucocorticoid-induced leucine zipper (GILZ.

    Directory of Open Access Journals (Sweden)

    Jingyue Liu

    Full Text Available BACKGROUND: Glucocorticoids (GCs are a first-line treatment for asthma for their anti-inflammatory effects, but they also hinder the repair of airway epithelial injury. The anti-inflammatory protein GC-induced leucine zipper (GILZ is reported to inhibit the activation of the mitogen-activated protein kinase (MAPK-extracellular-signal-regulated kinase (ERK signaling pathway, which promotes the repair of airway epithelial cells around the damaged areas. We investigated whether the inhibition of airway epithelial repair imposed by the GC dexamethasone (DEX is mediated by GILZ. METHODS: We tested the effect of DEX on the expressions of GILZ mRNA and GILZ protein and the MAPK-ERK signaling pathway in human airway epithelial cells, via RT-PCR and Western blot. We further evaluated the role of GILZ in mediating the effect of DEX on the MAPK-ERK signaling pathway and in airway epithelium repair by utilizing small-interfering RNAs, MTT, CFSE labeling, wound-healing and cell migration assays. RESULTS: DEX increased GILZ mRNA and GILZ protein levels in a human airway epithelial cell line. Furthermore, DEX inhibited the phosphorylation of Raf-1, Mek1/2, Erk1/2 (components of the MAPK-ERK signaling pathway, proliferation and migration. However, the inhibitory effect of DEX was mitigated in cells when the GILZ gene was silenced. CONCLUSIONS: The inhibition of epithelial injury repair by DEX is mediated in part by activation of GILZ, which suppressed activation of the MAPK-ERK signaling pathway, proliferation and migration. Our study implicates the involvement of DEX in this process, and furthers our understanding of the dual role of GCs.

  9. Repair-dependent cell radiation survival and transformation: an integrated theory.

    Science.gov (United States)

    Sutherland, John C

    2014-09-07

    The repair-dependent model of cell radiation survival is extended to include radiation-induced transformations. The probability of transformation is presumed to scale with the number of potentially lethal damages that are repaired in a surviving cell or the interactions of such damages. The theory predicts that at doses corresponding to high survival, the transformation frequency is the sum of simple polynomial functions of dose; linear, quadratic, etc, essentially as described in widely used linear-quadratic expressions. At high doses, corresponding to low survival, the ratio of transformed to surviving cells asymptotically approaches an upper limit. The low dose fundamental- and high dose plateau domains are separated by a downwardly concave transition region. Published transformation data for mammalian cells show the high-dose plateaus predicted by the repair-dependent model for both ultraviolet and ionizing radiation. For the neoplastic transformation experiments that were analyzed, the data can be fit with only the repair-dependent quadratic function. At low doses, the transformation frequency is strictly quadratic, but becomes sigmodial over a wider range of doses. Inclusion of data from the transition region in a traditional linear-quadratic analysis of neoplastic transformation frequency data can exaggerate the magnitude of, or create the appearance of, a linear component. Quantitative analysis of survival and transformation data shows good agreement for ultraviolet radiation; the shapes of the transformation components can be predicted from survival data. For ionizing radiations, both neutrons and x-rays, survival data overestimate the transforming ability for low to moderate doses. The presumed cause of this difference is that, unlike UV photons, a single x-ray or neutron may generate more than one lethal damage in a cell, so the distribution of such damages in the population is not accurately described by Poisson statistics. However, the complete

  10. Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells

    Science.gov (United States)

    Suzuki, Tetsuya; Yasui, Manabu

    2016-01-01

    Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Cells with a loss of heterozygosity (LOH) due to homologous recombination (HR) or nonhomologous end joining (NHEJ) can be restored with or without site-directed DSB induction. BLM cells exhibited a high frequency of spontaneous interallelic HR with crossover, but noncrossover events with long-tract gene conversions also occurred. Despite the highly interallelic HR events, BLM cells predominantly produced hemizygous LOH by spontaneous deletion. These phenotypes manifested during repair of DSBs. Both NHEJ and HR appropriately repaired DSBs in BLM cells, resulting in hemizygous and homozygous LOHs, respectively. However, the magnitude of the LOH was exacerbated in BLM cells, as evidenced by large deletions and long-tract gene conversions with crossover. BLM helicase suppresses the elongation of branch migration and crossover of double Holliday junctions (HJs) during HR repair, and a deficiency in this enzyme causes collapse, abnormal elongation, and/or preferable resolution to crossover of double HJs, resulting in a large-scale LOH. This mechanism underlies the predisposition for cancer in BS. PMID:27601585

  11. Mutator Phenotype and DNA Double-Strand Break Repair in BLM Helicase-Deficient Human Cells.

    Science.gov (United States)

    Suzuki, Tetsuya; Yasui, Manabu; Honma, Masamitsu

    2016-12-01

    Bloom syndrome (BS), an autosomal recessive disorder of the BLM gene, predisposes sufferers to various cancers. To investigate the mutator phenotype and genetic consequences of DNA double-strand breaks (DSBs) in BS cells, we developed BLM helicase-deficient human cells by disrupting the BLM gene. Cells with a loss of heterozygosity (LOH) due to homologous recombination (HR) or nonhomologous end joining (NHEJ) can be restored with or without site-directed DSB induction. BLM cells exhibited a high frequency of spontaneous interallelic HR with crossover, but noncrossover events with long-tract gene conversions also occurred. Despite the highly interallelic HR events, BLM cells predominantly produced hemizygous LOH by spontaneous deletion. These phenotypes manifested during repair of DSBs. Both NHEJ and HR appropriately repaired DSBs in BLM cells, resulting in hemizygous and homozygous LOHs, respectively. However, the magnitude of the LOH was exacerbated in BLM cells, as evidenced by large deletions and long-tract gene conversions with crossover. BLM helicase suppresses the elongation of branch migration and crossover of double Holliday junctions (HJs) during HR repair, and a deficiency in this enzyme causes collapse, abnormal elongation, and/or preferable resolution to crossover of double HJs, resulting in a large-scale LOH. This mechanism underlies the predisposition for cancer in BS. Copyright © 2016 Suzuki et al.

  12. The green microalga Tetraselmis suecica reduces oxidative stress and induces repairing mechanisms in human cells

    Science.gov (United States)

    Sansone, Clementina; Galasso, Christian; Orefice, Ida; Nuzzo, Genoveffa; Luongo, Elvira; Cutignano, Adele; Romano, Giovanna; Brunet, Christophe; Fontana, Angelo; Esposito, Francesco; Ianora, Adrianna

    2017-01-01

    Green microalgae contain many active pigments such as carotenoids having antioxidant and protective activity on human cells. Here we investigate the biological activity of an ethanol/water extract of the marine green microalga Tetraselmis suecica containing high levels of carotenoids such as the xanthophylls lutein, violaxanthin, neoxanthin, antheraxanthin and loroxanthin esters. This extract has a strong antioxidant and repairing activity in the human lung cancer cell line (A549) as shown by the increased expression of dehydrocholesterol reductase-24 (DHCR24) and prostaglandin reductase 1 (PTGR1) genes and proteins. The extract also reduces prostaglandin E2 (PGE2) levels in cells damaged by H2O2 and has tissue repairing effects on reconstructed human epidermal tissue cells (EpiDermTM) indicating a potential cosmeceutical activity of this microalgal species. PMID:28117410

  13. Establishment of the DNA repair-defective mutants in DT40 cells.

    Science.gov (United States)

    Ishiai, Masamichi; Uchida, Emi; Takata, Minoru

    2012-01-01

    The chicken B cell line DT40 has been widely used as a model system for reverse genetics studies in higher eukaryotes, because of its advantages including efficient gene targeting and ease of chromosome manipulation. Although the genetic approach using the RNA interference technique has become the standard method particularly in human cells, DT40 still remains a powerful tool to investigate the regulation and function of genes and proteins in a vertebrate system, because of feasibility of easy, rapid, and clear genetic experiments. The use of DT40 cells for DNA repair research has several advantages. In addition to canonical assays for DNA repair, such as measurement of the sensitivities toward DNA damage reagents, it is possible to measure homologous recombination and translesion synthesis activities using activation-induced deaminase (AID)-induced diversification of the immunoglobulin locus. In this chapter, we would describe a detailed protocol for gene disruption experiments in DT40 cells.

  14. The green microalga Tetraselmis suecica reduces oxidative stress and induces repairing mechanisms in human cells.

    Science.gov (United States)

    Sansone, Clementina; Galasso, Christian; Orefice, Ida; Nuzzo, Genoveffa; Luongo, Elvira; Cutignano, Adele; Romano, Giovanna; Brunet, Christophe; Fontana, Angelo; Esposito, Francesco; Ianora, Adrianna

    2017-01-24

    Green microalgae contain many active pigments such as carotenoids having antioxidant and protective activity on human cells. Here we investigate the biological activity of an ethanol/water extract of the marine green microalga Tetraselmis suecica containing high levels of carotenoids such as the xanthophylls lutein, violaxanthin, neoxanthin, antheraxanthin and loroxanthin esters. This extract has a strong antioxidant and repairing activity in the human lung cancer cell line (A549) as shown by the increased expression of dehydrocholesterol reductase-24 (DHCR24) and prostaglandin reductase 1 (PTGR1) genes and proteins. The extract also reduces prostaglandin E2 (PGE2) levels in cells damaged by H2O2 and has tissue repairing effects on reconstructed human epidermal tissue cells (EpiDerm(TM)) indicating a potential cosmeceutical activity of this microalgal species.

  15. Current focus of stem cell application in retinal repair

    Institute of Scientific and Technical Information of China (English)

    Maria L Alonso-Alonso; Girish Kumar Srivastava

    2015-01-01

    The relevance of retinal diseases, both in society'seconomy and in the quality of people's life who suffer withthem, has made stem cell therapy an interesting topic forresearch. Embryonic stem cells (ESCs), induced pluripotentstem cells (iPSCs) and adipose derived mesenchymal stemcells (ADMSCs) are the focus in current endeavors as asource of different retinal cells, such as photoreceptorsand retinal pigment epithelial cells. The aim is to applythem for cell replacement as an option for treating retinaldiseases which so far are untreatable in their advancedstage. ESCs, despite the great potential for differentiation,have the dangerous risk of teratoma formation as wellas ethical issues, which must be resolved before startinga clinical trial. iPSCs, like ESCs, are able to differentiatein to several types of retinal cells. However, the processto get them for personalized cell therapy has a high costin terms of time and money. Researchers are working toresolve this since iPSCs seem to be a realistic option fortreating retinal diseases. ADMSCs have the advantagethat the procedures to obtain them are easier. Despiteadvancements in stem cell application, there are stillseveral challenges that need to be overcome beforetransferring the research results to clinical application.This paper reviews recent research achievements of theapplications of these three types of stem cells as well asclinical trials currently based on them.

  16. Human endothelial stem/progenitor cells, angiogenic factors and vascular repair

    OpenAIRE

    Watt, Suzanne M.; Athanassopoulos, Athanasios; Harris, Adrian L.; Tsaknakis, Grigorios

    2010-01-01

    Neovascularization or new blood vessel formation is of utmost importance not only for tissue and organ development and for tissue repair and regeneration, but also for pathological processes, such as tumour development. Despite this, the endothelial lineage, its origin, and the regulation of endothelial development and function either intrinsically from stem cells or extrinsically by proangiogenic supporting cells and other elements within local and specific microenvironmental niches are stil...

  17. Homologous recombination preferentially repairs heat-induced DNA double-strand breaks in mammalian cells.

    Science.gov (United States)

    Takahashi, Akihisa; Mori, Eiichiro; Nakagawa, Yosuke; Kajihara, Atsuhisa; Kirita, Tadaaki; Pittman, Douglas L; Hasegawa, Masatoshi; Ohnishi, Takeo

    2016-11-13

    Heat shock induces DNA double-strand breaks (DSBs), but the precise mechanism of repairing heat-induced damage is unclear. Here, we investigated the DNA repair pathways involved in cell death induced by heat shock. B02, a specific inhibitor of human RAD51 (homologous recombination; HR), and NU7026, a specific inhibitor of DNA-PK (non-homologous end-joining; NHEJ), were used for survival assays of human cancer cell lines with different p53-gene status. Mouse embryonic fibroblasts (MEFs) lacking Lig4 (NHEJ) and/or Rad54 (HR) were used for survival assays and a phosphorylated histone H2AX at Ser139 (γH2AX) assay. MEFs lacking Rad51d (HR) were used for survival assays. SPD8 cells were used to measure HR frequency after heat shock. Human cancer cells were more sensitive to heat shock in the presence of B02 despite their p53-gene status, and the effect of B02 on heat sensitivity was specific to the G2 phase. Rad54-deficient MEFs were sensitive to heat shock and showed prolonged γH2AX signals following heat shock. Rad51d-deficient MEFs were also sensitive to heat shock. Moreover, heat shock-stimulated cells had increased HR. The HR pathway plays an important role in the survival of mammalian cells against death induced by heat shock via the repair of heat-induced DNA DSBs.

  18. Skin-resident T cells sense ultraviolet radiation-induced injury and contribute to DNA repair.

    Science.gov (United States)

    MacLeod, Amanda S; Rudolph, Ross; Corriden, Ross; Ye, Ivan; Garijo, Olivia; Havran, Wendy L

    2014-06-15

    Skin-resident T cells have been shown to play important roles in tissue homeostasis and wound repair, but their role in UV radiation (UVR)-mediated skin injury and subsequent tissue regeneration is less clear. In this study, we demonstrate that acute UVR rapidly activates skin-resident T cells in humans and dendritic epidermal γδ T cells (DETCs) in mice through mechanisms involving the release of ATP from keratinocytes. Following UVR, extracellular ATP leads to an increase in CD69 expression, proliferation, and IL-17 production, and to changes in DETC morphology. Furthermore, we find that the purinergic receptor P2X7 and caspase-1 are necessary for UVR-induced IL-1 production in keratinocytes, which increases IL-17 secretion by DETCs. IL-17, in turn, induces epidermal TNF-related weak inducer of apoptosis and growth arrest and DNA damage-associated gene 45, two molecules linked to the DNA repair response. Finally, we demonstrate that DETCs and human skin-resident T cells limit DNA damage in keratinocytes. Taken together, our findings establish a novel role for skin-resident T cells in the UVR-associated DNA repair response and underscore the importance of skin-resident T cells to overall skin regeneration.

  19. Heterogeneous Stem Cells in Skin Homeostatis and Wound Repair

    Directory of Open Access Journals (Sweden)

    Anna Meilana

    2015-08-01

    Full Text Available BACKGROUND: The skin protects mammals from insults, infection and dehydration and enables thermoregulation and sensory perception. Various skin-resident cells carry out these diverse functions. Constant turnover of cells and healing upon injury necessitate multiple reservoirs of stem cells. The skin is a complex organ harboring several distinct populations of stem cells and a rich array of cell types. Advances in genetic and imaging tools have brought new findings about the lineage relationships between skin stem cells and their progeny. Such knowledge may offer novel avenues for therapeutics and regenerative medicine. CONTENT: In the past years, our view of the mechanisms that govern skin homeostasis and regeneration have markedly changed. New populations of stem cells have been identified that behave spatio-temporally differently in healthy tissues and in situations of damage, indicating that a great level of stem cell heterogeneity is present in the skin. There are believed to be distinct populations of stem cells in different locations. The lineages that they feed are normally constrained by signals from their local environment, but they can give rise to all epidermal lineages in response to appropriate stimuli. Given the richness of structures such as blood vessels, subcutaneous fat, innervation and the accumulation of fibroblasts under the upper parts of the rete ridges (in the case of human skin, it is reasonable to speculate that the microenvironment might be essential for interfollicular epidermal homeostasis. The bloodstream is probably the main source of long-range signals reaching the skin, and cues provided by the vascular niche might be essential for skin homeostasis. SUMMARY: A key function of the interfollicular epidermis is to act as a protective interface between the body and the external environment, and it contains several architectural elements that enable it to fulfill this function. All elements of the epidermis play

  20. A novel layered perovskite as symmetric electrode for direct hydrocarbon solid oxide fuel cells

    Science.gov (United States)

    Zhao, Ling; Chen, Kongfa; Liu, Yuanxu; He, Beibei

    2017-02-01

    Layered perovskite oxides are well known to possess significant electronic, magnetic and electrochemical properties. Herein, we highlight a novel layered perovskite PrBaMn1.5Fe0.5O5+δ (PBMFO) as electrodes of symmetrical solid oxide fuel cells (SSOFCs). The layered PBMFO shows high electrical conductivity of 112.5 and 7.4 S cm-1 at 800 °C in air and 5% H2/Ar, respectively. The single cell with PBMFO symmetric electrodes achieves peak power density of 0.54 W cm-2 at 800 °C using humidified hydrogen as fuel. Moreover, PBMFO electrodes demonstrate good redox stability and high coking tolerance against hydrocarbon fuel.

  1. Axonal outgrowth is associated with increased ERK 1/2 activation but decreased caspase 3 linked cell death in Schwann cells after immediate nerve repair in rats

    Directory of Open Access Journals (Sweden)

    Kanje Martin

    2011-01-01

    Full Text Available Abstract Background Extracellular-signal regulated kinase (ERK1/2 is activated by nerve damage and its activation precedes survival and proliferation of Schwann cells. In contrast, activation of caspase 3, a cysteine protease, is considered as a marker for apoptosis in Schwann cells. In the present study, axonal outgrowth, activation of ERK1/2 by phosphorylation (p-ERK 1/2 and immunoreactivity of cleaved caspase 3 were examined after immediate, delayed, or no repair of transected rat sciatic nerves. Results Axonal outgrowth, detected by neurofilament staining, was longer after immediate repair than after either the delayed or no repair conditions. Immediate repair also showed a higher expression of p-ERK 1/2 and a lower number of cleaved caspase 3 stained Schwann cells than after delayed nerve repair. If the transected nerve was not repaired a lower level of p-ERK 1/2 was found than in either the immediate or delayed repair conditions. Axonal outgrowth correlated to p-ERK 1/2, but not clearly with cleaved caspase 3. Contact with regenerating axons affected Schwann cells with respect to p-ERK 1/2 and cleaved caspase 3 after immediate nerve repair only. Conclusion The decreased regenerative capacity that has historically been observed after delayed nerve repair may be related to impaired activation of Schwann cells and increased Schwann cell death. Outgrowing axons influence ERK 1/2 activation and apoptosis of Schwann cells.

  2. Stem cells in stroke repair: current success and future prospects.

    Science.gov (United States)

    Gopurappilly, Renjitha; Pal, Rajarshi; Mamidi, Murali Krishna; Dey, Sovan; Bhonde, Ramesh; Das, Anjan Kumar

    2011-09-01

    Stroke causes a devastating insult to the brain resulting in severe neurological deficits because of a massive loss of different neurons and glia. In the United States, stroke is the third leading cause of death. Stroke remains a significant clinical unmet condition, with only 3% of the ischemic patient population benefiting from current treatment modalities, such as the use of thrombolytic agents, which are often limited by a narrow therapeutic time window. However, regeneration of the brain after ischemic damage is still active days and even weeks after stroke occurs, which might provide a second window for treatment. Neurorestorative processes like neurogenesis, angiogenesis and synaptic plasticity lead to functional improvement after stroke. Stem cells derived from various tissues have the potential to perform all of the aforementioned processes, thus facilitating functional recovery. Indeed, transplantation of stem cells or their derivatives in animal models of cerebral ischemia can improve function by replacing the lost neurons and glial cells and by mediating remyelination, and modulation of inflammation as confirmed by various studies worldwide. While initially stem cells seemed to work by a 'cell replacement' mechanism, recent research suggests that cell therapy works mostly by providing trophic support to the injured tissue and brain, fostering both neurogenesis and angiogenesis. Moreover, ongoing human trials have encouraged hopes for this new method of restorative therapy after stroke. This review describes up-to-date progress in cell-based therapy for the treatment of stroke. Further, as we discuss here, significant hurdles remain to be addressed before these findings can be responsibly translated to novel therapies. In particular, we need a better understanding of the mechanisms of action of stem cells after transplantation, the therapeutic time window for cell transplantation, the optimal route of cell delivery to the ischemic brain, the most

  3. Assessment of okadaic acid effects on cytotoxicity, DNA damage and DNA repair in human cells.

    Science.gov (United States)

    Valdiglesias, Vanessa; Méndez, Josefina; Pásaro, Eduardo; Cemeli, Eduardo; Anderson, Diana; Laffon, Blanca

    2010-07-07

    Okadaic acid (OA) is a phycotoxin produced by several types of dinoflagellates causing diarrheic shellfish poisoning (DSP) in humans. Symptoms induced by DSP toxins are mainly gastrointestinal, but the intoxication does not appear to be fatal. Despite this, this toxin presents a potential threat to human health even at concentrations too low to induce acute toxicity, since previous animal studies have shown that OA has very potent tumour promoting activity. However, its concrete action mechanism has not been described yet and the results reported with regard to OA cytotoxicity and genotoxicity are often contradictory. In the present study, the genotoxic and cytotoxic effects of OA on three different types of human cells (peripheral blood leukocytes, HepG2 hepatoma cells, and SHSY5Y neuroblastoma cells) were evaluated. Cells were treated with a range of OA concentrations in the presence and absence of S9 fraction, and MTT test and Comet assay were performed in order to evaluate cytotoxicity and genotoxicity, respectively. The possible effects of OA on DNA repair were also studied by means of the DNA repair competence assay, using bleomycin as DNA damage inductor. Treatment with OA in absence of S9 fraction induced not statistically significant decrease in cell viability and significant increase in DNA damage in all cell types at the highest concentrations investigated. However, only SHSY5Y cells showed OA induced genotoxic and cytotoxic effects in presence of S9 fraction. Furthermore, we found that OA can induce modulations in DNA repair processes when exposure was performed prior to BLM treatment, in co-exposure, or during the subsequent DNA repair process. Copyright 2010 Elsevier B.V. All rights reserved.

  4. Aryl hydrocarbon receptor inhibition promotes hematolymphoid development from human pluripotent stem cells.

    Science.gov (United States)

    Angelos, Mathew G; Ruh, Paige N; Webber, Beau R; Blum, Robert H; Ryan, Caitlin D; Bendzick, Laura; Shim, Seonhui; Yingst, Ashley M; Tufa, Dejene M; Verneris, Michael R; Kaufman, Dan S

    2017-06-29

    The aryl hydrocarbon receptor (AHR) plays an important physiological role in hematopoiesis. AHR is highly expressed in hematopoietic stem and progenitor cells (HSPCs) and inhibition of AHR results in a marked expansion of human umbilical cord blood-derived HSPCs following cytokine stimulation. It is unknown whether AHR also contributes earlier in human hematopoietic development. To model hematopoiesis, human embryonic stem cells (hESCs) were allowed to differentiate in defined conditions in the presence of the AHR antagonist StemReginin-1 (SR-1) or the AHR agonist 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We demonstrate a significant increase in CD34(+)CD31(+) hematoendothelial cells in SR-1-treated hESCs, as well as a twofold expansion of CD34(+)CD45(+) hematopoietic progenitor cells. Hematopoietic progenitor cells were also significantly increased by SR-1 as quantified by standard hematopoietic colony-forming assays. Using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)-engineered hESC-RUNX1c-tdTomato reporter cell line with AHR deletion, we further demonstrate a marked enhancement of hematopoietic differentiation relative to wild-type hESCs. We also evaluated whether AHR antagonism could promote innate lymphoid cell differentiation from hESCs. SR-1 increased conventional natural killer (cNK) cell differentiation, whereas TCDD treatment blocked cNK development and supported group 3 innate lymphoid cell (ILC3) differentiation. Collectively, these results demonstrate that AHR regulates early human hematolymphoid cell development and may be targeted to enhance production of specific cell populations derived from human pluripotent stem cells. © 2017 by The American Society of Hematology.

  5. DNA lesions, inducible DNA repair, and cell division: Three key factors in mutagenesis and carcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Ames, B.N.; Shigenaga, M.K. [Univ. of California, Berkeley, CA (United States); Gold, L.S. [Lawrence Berkeley National Lab., CA (United States)

    1993-12-01

    DNA lesions that escape repair have a certain probability of giving rise to mutations when the cell divides. Endogenous DNA damage is high: 10{sup 6} oxidative lesions are present per rat cell. An exogenous mutagen produces an increment in lesions over the background rate of endogenous lesions. The effectiveness of a particular lesion depends on whether it is excised by a DNA repair system and the probability that it gives rise to a mutation when the cell divides. When the cell divides, an unrepaired DNA lesion has a certain probability of giving rise to a mutation. Thus, an important factor in the mutagenic effect of an exogenous agent whether it is genotoxic or non-genotoxic, is the increment it causes over the background cell division rate (mitogenesis) in cells that appear to matter most in cancer, the stem cells, which are not on their way to being discarded. Increasing their cell division rate increases by high doses of chemicals. If both the rate of DNA lesions and cell division are increased, then there will be a multiplicative effect on mutagenesis (and carcinogenesis), for example, by high doses of a mutagen that also increases mitogenesis through cell killing. The defense system against reactive electrophilic mutagens, such as the glutathione transferases, are also almost all inducible and buffer cells against increments in active forms of chemicals that can cause DNA lesions. A variety of DNA repair defense systems, almost all inducible, buffer the cell against any increment in DNA lesions. Therefore, the effect of a particular chemical insult depends on the level of each defense, which in turn depends on the past history of exposure. Exogenous agents can influence the induction and effectiveness of these defenses. Defenses can be partially disabled by lack of particular micronutrients in the diet (e.g., antioxidants).

  6. Changes in gene expression induced by polycyclic aromatic hydrocarbons in the human cell lines HepG2 and A549.

    Science.gov (United States)

    Castorena-Torres, Fabiola; Bermúdez de León, Mario; Cisneros, Bulmaro; Zapata-Pérez, Omar; Salinas, Juan E; Albores, Arnulfo

    2008-03-01

    Polycyclic aromatic hydrocarbons (PAH) are the main components of emissions generated by coke oven factories and many of these chemicals are carcinogenic. The goal of this study was to examine changes in gene expression in two human cell lines, HepG2 and A549, induced by exposure to a soil extract containing PAH using microarry technology. Soil samples were obtained from the vicinity of a coke oven factory in northeastern Mexico. For comparison, the gene expression pattern induced by Benz[a]pyrene (BaP) was also analyzed. The number of altered genes by both treatments was 2-fold higher in hepatic than in pulmonary cells. Differentially-modulated genes in the two cell lines were identified and grouped by biological function using genomic databases. A group of nine genes up- and down-regulated by either the PAH extract or BaP were selected for validation by real-time PCR. The cellular functions of these PAH-responsive genes included: xenobiotic metabolism (CYP1A1 and CYP1B1), DNA repair (ERCC5), oxidative stress response and cell proliferation (FTH1 and PRDX1), protein degradation (PSMD7), ion transport (FXYD3), steroid biosynthesis (FDFT1), and signaling pathways (PTGER3). The real-time PCR analysis confirmed most of the microarray data with significant correlation. Additional studies are required to determine the mechanisms involved in the PAH-mediated modulation of these genes and to associate these changes with human health.

  7. How do resident stem cells repair the damagedmyocardium?

    Institute of Scientific and Technical Information of China (English)

    Emiko Hayashi; Toru Hosoda

    2015-01-01

    It has been a decade since the monumental discoveryof resident stem cells in the mammalian heart, and thefollowing studies witnessed the continuous turnoverof cardiomyocytes and vascular cells, maintaining thehomeostasis of the organ. Recently, the autologousadministration of c-kit-positive cardiac stem cells inpatients with ischemic heart failure has led to an incredibleoutcome; the left ventricular ejection fraction of the celltreatedgroup improved from 30% at the baseline to 38%after one year and to 42% after two years of cell injection.The potential underlying mechanisms, before and aftercell infusion, are explored and discussed in this article.Some of them are related to the intrinsic property of theresident stem cells, such as direct differentiation, paracrineaction, and immunomodulatory function, whereas othersinvolve environmental factors, leading to cellular reverseremodeling and to the natural selection of "juvenile" cells.It has now been demonstrated that cardiac stem cells fortherapeutic purposes can be prepared from tiny biopsiedspecimens of the failing heart as well as from frozentissues, which may remarkably expand the repertoireof the strategy against various cardiovascular disorders,including non-ischemic cardiomyopathy and congenitalheart diseases. Further translational investigations areneeded to explore these possibilities.

  8. Human POLD1 modulates cell cycle progression and DNA damage repair

    OpenAIRE

    Song, Jing; Hong, Ping; Liu, Chengeng; Zhang, Yueqi; Wang, Jinling; Wang, Peichang

    2015-01-01

    Background The activity of eukaryotic DNA polymerase delta (Pol δ) plays an essential role in genome stability through its effects on DNA replication and repair. The p125 catalytic subunit of Pol δ is encoded by POLD1 gene in human cells. To clarify biological functions of POLD1, we investigated the effects of POLD1 overexpression or downregulation on cell proliferation, cell cycle progression, DNA synthesis and oxidative DNA damage induced by H2O2. Methods HEK293 cells were transfected with ...

  9. Potential use of mesenchymal stem cells in human meniscal repair: current insights

    Science.gov (United States)

    Pak, Jaewoo; Lee, Jung Hun; Park, Kwang Seung; Jeon, Jeong Ho; Lee, Sang Hee

    2017-01-01

    The menisci of the human knee play an important role in maintaining normal functions to provide stability and nutrition to the articular cartilage, and to absorb shock. Once injured, these important structures have very limited natural healing potential. Unfortunately, the traditional arthroscopic meniscectomy performed on these damaged menisci may predispose the joint toward early development of osteoarthritis. Although a very limited number of studies are available, mesenchymal stem cells (MSCs) have been investigated as an alternative therapeutic modality to repair human knee meniscal tears. This review summarizes the results of published applications of MSCs in human patients, which showed that the patients who received MSCs (autologous adipose tissue-derived stem cells or culture-expanded bone marrow-derived stem cells) presented symptomatic improvements, along with magnetic resonance imaging evidences of the meniscal repair. PMID:28356779

  10. Age-associated changes in regenerative capabilities of mesenchymal stem cell: impact on chronic wounds repair.

    Science.gov (United States)

    Yao, Bin; Huang, Sha; Gao, Dongyun; Xie, Jiangfan; Liu, Nanbo; Fu, Xiaobing

    2016-12-01

    Mesenchymal stem cells (MSCs) represent an ideal source of autologous cell-based therapy for chronic wounds. Functional characteristics of MSCs may benefit wound healing by exerting their multi-regenerative potential. However, cell ageing resulting from chronic degenerative diseases or donor age could cause inevitable effects on the regenerative abilities of MSCs. A variety of studies have shown the relationship between MSC ageing and age-related dysfunction, but few associate these age-related impacts on MSCs with their ability of repairing chronic wounds, which are common in the elderly population. Here, we discuss the age-associated changes of MSCs and describe the potential impacts on MSC-based therapy for chronic wounds. Furthermore, critical evaluation of the current literatures is necessary for understanding the underlying mechanisms of MSC ageing and raising the corresponding concerns on considering their possible use for chronic wound repair. © 2015 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  11. In Vivo Reprogramming for CNS Repair: Regenerating Neurons from Endogenous Glial Cells

    Science.gov (United States)

    Li, Hedong; Chen, Gong

    2017-01-01

    Neuroregeneration in the central nervous system (CNS) has proven to be difficult despite decades of research. The old dogma that CNS neurons cannot be regenerated in the adult mammalian brain has been overturned; however, endogenous adult neurogenesis appears to be insufficient for brain repair. Stem cell therapy once held promise for generating large quantities of neurons in the CNS, but immunorejection and long-term functional integration remain major hurdles. In this perspective, we discuss the use of in vivo reprogramming as an emerging technology to regenerate functional neurons from endogenous glial cells inside the brain and spinal cord. Besides the CNS, in vivo reprogramming has been demonstrated successfully in the pancreas, heart and liver, and may be adopted in other organs. Although challenges remain for translating this technology into clinical therapies, we anticipate that in vivo reprogramming may revolutionize regenerative medicine by using a patient’s own internal cells for tissue repair. PMID:27537482

  12. Parthenogenetic stem cells for tissue-engineered heart repair

    NARCIS (Netherlands)

    Didie, Michael; Christalla, Peter; Rubart, Michael; Muppala, Vijayakumar; Doeker, Stephan; Unsoeld, Bernhard; El-Armouche, Ali; Rau, Thomas; Eschenhagen, Thomas; Schwoerer, Alexander P.; Ehmke, Heimo; Schumacher, Udo; Fuchs, Sigrid; Lange, Claudia; Becker, Alexander; Tao, Wen; Scherschel, John A.; Soonpaa, Mark H.; Yang, Tao; Lin, Qiong; Zenke, Martin; Han, Dong-Wook; Schoeler, Hans R.; Rudolph, Cornelia; Steinemann, Doris; Schlegelberger, Brigitte; Kattman, Steve; Witty, Alec; Keller, Gordon; Field, Loren J.; Zimmermann, Wolfram-Hubertus

    2013-01-01

    Uniparental parthenotes are considered an unwanted byproduct of in vitro fertilization. In utero parthenote development is severely compromised by defective organogenesis and in particular by defective cardiogenesis. Although developmentally compromised, apparently pluripotent stem cells can be deri

  13. "Second-generation" stem cells for cardiac repair

    Institute of Scientific and Technical Information of China (English)

    Alberto Nú?ez García; Ricardo Sanz-Ruiz; María Eugenia Fernández Santos; Francisco Fernández-Avilés

    2015-01-01

    Over the last years, stem cell therapy has emerged asan inspiring alternative to restore cardiac function aftermyocardial infarction. A large body of evidence has beenobtained in this field but there is no conclusive data onthe efficacy of these treatments. Preclinical studies andearly reports in humans have been encouraging andhave fostered a rapid clinical translation, but positiveresults have not been uniformly observed and whenpresent, they have been modest. Several types ofstem cells, manufacturing methods and delivery routeshave been tested in different clinical settings but directcomparison between them is challenging and hindersfurther research. Despite enormous achievements,major barriers have been found and many fundamentalissues remain to be resolved. A better knowledgeof the molecular mechanisms implicated in cardiacdevelopment and myocardial regeneration is criticallyneeded to overcome some of these hurdles. Genetic andpharmacological priming together with the discovery ofnew sources of cells have led to a "second generation"of cell products that holds an encouraging promise incardiovascular regenerative medicine. In this report,we review recent advances in this field focusing on thenew types of stem cells that are currently being testedin human beings and on the novel strategies employedto boost cell performance in order to improve cardiacfunction and outcomes after myocardial infarction.

  14. The Polycomb Group Protein EZH2 Impairs DNA Repair in Breast Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Michael Zeidler

    2005-11-01

    Full Text Available The Polycomb group protein EZH2 is a transcriptional repressor involved in controlling cellular memory and has been linked to aggressive and metastatic breast cancer. Here we report that EZH2 decreased the expression of five RAD51 paralog proteins involved in homologous recombination (HR repair of DNA doublestrand breaks (RAD51B/RAD51L1, RAD51C/RAD51L2, RAD51D/RAD51L3, XRCC2, and XRCC3, but did not affect the levels of DMC1, a gene that only functions in meiosis. EZH2 overexpression impaired the formation of RAD51 repair foci at sites of DNA breaks. Overexpression of EZH2 resulted in decreased cell survival and clonogenic capacity following DNA damage induced independently by etoposide and ionizing radiation. We suggest that EZH2 may contribute to breast tumorigenesis by specific downregulation of RAD51-like proteins and by impairment of HR repair. We provide mechanistic insights into the function of EZH2 in mammalian cells and uncover a link between EZH2, a regulator of homeotic gene expression, and HR DNA repair. Our study paves the way for exploring the blockade of EZH2 overexpression as a novel approach for the prevention and treatment of breast cancer.

  15. Iron oxide labelling of human mesenchymal stem cells in collagen hydrogels for articular cartilage repair.

    Science.gov (United States)

    Heymer, Andrea; Haddad, Daniel; Weber, Meike; Gbureck, Uwe; Jakob, Peter M; Eulert, Jochen; Nöth, Ulrich

    2008-04-01

    For the development of new therapeutical cell-based strategies for articular cartilage repair, a reliable cell monitoring technique is required to track the cells in vivo non-invasively and repeatedly. We present a systematic and detailed study on the performance and biological impact of a simple and efficient labelling protocol for human mesenchymal stem cells (hMSCs). Commercially available very small superparamagnetic iron oxide particles (VSOPs) were used as magnetic resonance (MR) contrast agent. Iron uptake via endocytosis was confirmed histologically with prussian blue staining and quantified by mass spectrometry. Compared with unlabelled cells, VSOP-labelling did neither influence the viability nor the proliferation potential of hMSCs. Furthermore, iron incorporation did not affect hMSCs in undergoing adipogenic, osteogenic or chondrogenic differentiation, as demonstrated histologically and by gene expression analyses. The efficiency of the labelling protocol was assessed with high-resolution MR imaging at 11.7T. VSOP-labelled hMSCs were visualised in a collagen type I hydrogel, which is in clinical use for matrix-based articular cartilage repair. The presence of VSOP-labelled hMSCs was indicated by distinct hypointense spots in the MR images, as a result of iron specific loss of signal intensity. In summary, this labelling technique has great potential to visualise hMSCs and track their migration after transplantation for articular cartilage repair with MR imaging.

  16. Extracellular calpains increase tubular epithelial cell mobility. Implications for kidney repair after ischemia.

    Science.gov (United States)

    Frangié, Carlos; Zhang, Wenhui; Perez, Joëlle; Dubois, Yi-Chun Xu; Haymann, Jean-Philippe; Baud, Laurent

    2006-09-08

    Calpains are intracellular Ca2+-dependent cysteine proteases that are released in the extracellular milieu by tubular epithelial cells following renal ischemia. Here we show that externalized calpains increase epithelial cell mobility and thus are critical for tubule repair. In vitro, exposure of human tubular epithelial cells (HK-2 cells) to mu-calpain limited their adhesion to extracellular matrix and increased their mobility. Calpains acted primarily by promoting the cleavage of fibronectin, thus preventing fibronectin binding to the integrin alphavbeta3. Analyzing downstream integrin effects, we found that the cyclic AMP-dependent protein kinase A pathway was activated in response to alphavbeta3 disengagement and was essential for calpain-mediated increase in HK-2 cell mobility. In a murine model of ischemic acute renal failure, injection of a fragment of calpastatin, which specifically blocked calpain activity in extracellular milieu, markedly delayed tubule repair, increasing functional and histological lesions after 24 and 48 h of reperfusion. These findings suggest that externalized calpains are critical for tubule repair process in acute renal failure.

  17. Omeprazole Inhibits Pancreatic Cancer Cell Invasion through a Nongenomic Aryl Hydrocarbon Receptor Pathway.

    Science.gov (United States)

    Jin, Un-Ho; Kim, Sang-Bae; Safe, Stephen

    2015-05-18

    Omeprazole and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are aryl hydrocarbon receptor (AhR) agonists that inhibit the invasion of breast cancer cells through inhibition of CXCR4 transcription. Treatment of highly invasive Panc1 pancreatic cancer cells with TCDD, omeprazole, and seven other AhR-active pharmaceuticals showed that only omeprazole and tranilast, but not TCDD, inhibited invasion in a Boyden chamber assay. Similar results were observed in MiaPaCa2 cells, another quasimensenchymal pancreatic ductal adenocarcinoma (QM-PDA) pancreatic cancer cell line, whereas invasion was not observed with BxPC3 or L3.6pL cells, which are classified as classical (less invasive) pancreatic cancer cells. It was also observed in QM-PDA cells that TCDD, omeprazole, and tranilast did not induce CYP1A1 or CXCR4 and that treatment with these compounds did not result in nuclear uptake of AhR. In contrast, treatment of BxPC3 and L3.6pL cells with these AhR ligands resulted in induction of CYP1A1 (by TCDD) and nuclear uptake of AhR, which was similar to that observed for Ah-responsive MDA-MB-468 breast and HepG2 liver cancer cell lines. Results of AhR and AhR nuclear translocator (Arnt) knockdown experiments in Panc1 and MiaPaCa2 cells demonstrated that omeprazole- and tranilast-mediated inhibition of invasion was AhR-dependent but Arnt-independent. These results demonstrate that in the most highly invasive subtype of pancreatic cancer cells (QM-PDA) the selective AhR modulators omeprazole and tranilast inhibit invasion through a nongenomic AhR pathway.

  18. Wound repair and anti-oxidative capacity is regulated by ITGB4 in airway epithelial cells.

    Science.gov (United States)

    Liu, Chi; Liu, Hui-jun; Xiang, Yang; Tan, Yu-rong; Zhu, Xiao-lin; Qin, Xiao-qun

    2010-08-01

    Integrin beta 4 (ITGB4) is a structural adhesion molecule which engages in maintaining the integrity of airway epithelial cells. Its specific cytomembrane structural feature strongly indicates that ITGB4 may engage in many signaling pathways and physiologic processes. However, in addition to adhesion, the specific biologic significance of ITGB4 in airway epithelial cells is almost unknown. In this article, we investigated the expression and functional properties of ITGB4 in airway epithelial cells in vivo and in vitro. Human bronchial epithelial cell line (16HBE14O-cells) and primary rat tracheal epithelial cells (RTE cells) were used to determine ITGB4 expression under ozone tress or mechanical damage, respectively. An ovalbumin (OVA)-challenged asthma model was used to investigate ITGB4 expression after antigen exposure in vivo. In addition, an ITGB4 overexpression vector and ITGB4 silence virus vector were constructed and transfected into RTE cells. Then, wound repair ability and anti-oxidation capacity was evaluated. Our results demonstrated that, on the edge of mechanically wounded cell areas, ITGB4 expression was increased after mechanical injury. After ozone stress, upregulation expression of ITGB4 was also detected. In the OVA-challenged asthma model, ITGB4 expression was decreased on airway epithelial cells accompanying with structural disruption and damage of anti-oxidation capacity. Besides, our study revealed that upregulation of ITGB4 promotes wound repair ability and anti-oxidative ability, while such abilities were blocked when ITGB4 was silenced. Taken together, these results showed that ITGB4 was a new interesting molecule involved in the regulation of wound repair and anti-oxidation processes for airway epithelial cells.

  19. The emerging role of aryl hydrocarbon receptor in the activation and differentiation of Th17 cells.

    Science.gov (United States)

    Baricza, Eszter; Tamási, Viola; Marton, Nikolett; Buzás, Edit I; Nagy, György

    2016-01-01

    The aryl hydrocarbon receptor (AHR) is a cytoplasmic transcription factor, which plays an essential role in the xenobiotic metabolism in a wide variety of cells. The AHR gene is evolutionarily conserved and it has a central role not only in the differentiation and maturation of many tissues, but also in the toxicological metabolism of the cell by the activation of metabolizing enzymes. Several lines of evidence support that both AHR agonists and antagonists have profound immunological effects; and recently, the AHR has been implicated in antibacterial host defense. According to recent studies, the AHR is essential for the differentiation and activation of T helper 17 (Th17) cells. It is well known that Th17 cells have a central role in the development of inflammation, which is crucial in the defense against pathogens. In addition, Th17 cells play a major role in the pathogenesis of several autoimmune diseases such as rheumatoid arthritis. Therefore, the AHR may provide connection between the environmental chemicals, the immune regulation, and autoimmunity. In the present review, we summarize the role of the AHR in the Th17 cell functions.

  20. Petroleum Diesel and Biodiesel Fuels Used in a Direct Hydrocarbon Phosphoric Acid Fuel Cell

    Directory of Open Access Journals (Sweden)

    Yuanchen Zhu

    2015-01-01

    Full Text Available The performance of a direct hydrocarbon phosphoric acid fuel cell, PAFC, was investigated using petroleum diesel, biodiesel, and n-hexadecane as the fuels. We believe this is the first study of a fuel cell being operated with petroleum diesel as the fuel at the anode. Degradation in fuel cell performance was observed prior to reaching steady state. The degradation was attributed to a carbonaceous material forming on the surface of the anode. Regardless of the initial degradation, a steady-state operation was achieved with each of the diesel fuels. After treating the anode with water the fuel cell performance recovered. However, the fuel cell performance degraded again prior to obtaining another steady-state operation. There were several observations that were consistent with the suggestion that the carbonaceous material formed from the diesel fuels might be a reaction intermediate necessary for steady-state operation. Finally, the experiments indicated that water in the phosphoric acid electrolyte could be used as the water required for the anodic reaction. The water formed at the cathode could provide the replacement water for the electrolyte, thereby eliminating the need to provide a water feed system for the fuel cell.

  1. Pluripotency factors and Polycomb Group proteins repress aryl hydrocarbon receptor expression in murine embryonic stem cells

    Directory of Open Access Journals (Sweden)

    Chia-I Ko

    2014-01-01

    Full Text Available The aryl hydrocarbon receptor (AHR is a transcription factor and environmental sensor that regulates expression of genes involved in drug-metabolism and cell cycle regulation. Chromatin immunoprecipitation analyses, Ahr ablation in mice and studies with orthologous genes in invertebrates suggest that AHR may also play a significant role in embryonic development. To address this hypothesis, we studied the regulation of Ahr expression in mouse embryonic stem cells and their differentiated progeny. In ES cells, interactions between OCT3/4, NANOG, SOX2 and Polycomb Group proteins at the Ahr promoter repress AHR expression, which can also be repressed by ectopic expression of reprogramming factors in hepatoma cells. In ES cells, unproductive RNA polymerase II binds at the Ahr transcription start site and drives the synthesis of short abortive transcripts. Activation of Ahr expression during differentiation follows from reversal of repressive marks in Ahr promoter chromatin, release of pluripotency factors and PcG proteins, binding of Sp factors, establishment of histone marks of open chromatin, and engagement of active RNAPII to drive full-length RNA transcript elongation. Our results suggest that reversible Ahr repression in ES cells holds the gene poised for expression and allows for a quick switch to activation during embryonic development.

  2. Pluripotency factors and Polycomb Group proteins repress aryl hydrocarbon receptor expression in murine embryonic stem cells.

    Science.gov (United States)

    Ko, Chia-I; Wang, Qin; Fan, Yunxia; Xia, Ying; Puga, Alvaro

    2014-01-01

    The aryl hydrocarbon receptor (AHR) is a transcription factor and environmental sensor that regulates expression of genes involved in drug-metabolism and cell cycle regulation. Chromatin immunoprecipitation analyses, Ahr ablation in mice and studies with orthologous genes in invertebrates suggest that AHR may also play a significant role in embryonic development. To address this hypothesis, we studied the regulation of Ahr expression in mouse embryonic stem cells and their differentiated progeny. In ES cells, interactions between OCT3/4, NANOG, SOX2 and Polycomb Group proteins at the Ahr promoter repress AHR expression, which can also be repressed by ectopic expression of reprogramming factors in hepatoma cells. In ES cells, unproductive RNA polymerase II binds at the Ahr transcription start site and drives the synthesis of short abortive transcripts. Activation of Ahr expression during differentiation follows from reversal of repressive marks in Ahr promoter chromatin, release of pluripotency factors and PcG proteins, binding of Sp factors, establishment of histone marks of open chromatin, and engagement of active RNAPII to drive full-length RNA transcript elongation. Our results suggest that reversible Ahr repression in ES cells holds the gene poised for expression and allows for a quick switch to activation during embryonic development.

  3. Helicobacter pylori Disrupts Host Cell Membranes, Initiating a Repair Response and Cell Proliferation

    Directory of Open Access Journals (Sweden)

    Hsueh-Fen Juan

    2012-08-01

    Full Text Available Helicobacter pylori (H. pylori, the human stomach pathogen, lives on the inner surface of the stomach and causes chronic gastritis, peptic ulcer, and gastric cancer. Plasma membrane repair response is a matter of life and death for human cells against physical and biological damage. We here test the hypothesis that H. pylori also causes plasma membrane disruption injury, and that not only a membrane repair response but also a cell proliferation response are thereby activated. Vacuolating cytotoxin A (VacA and cytotoxin-associated gene A (CagA have been considered to be major H. pylori virulence factors. Gastric cancer cells were infected with H. pylori wild type (vacA+/cagA+, single mutant (ΔvacA or ΔcagA or double mutant (ΔvacA/ΔcagA strains and plasma membrane disruption events and consequent activation of membrane repair components monitored. H. pylori disrupts the host cell plasma membrane, allowing localized dye and extracellular Ca2+ influx. Ca2+-triggered members of the annexin family, A1 and A4, translocate, in response to injury, to the plasma membrane, and cell surface expression of an exocytotic maker of repair, LAMP-2, increases. Additional forms of plasma membrane disruption, unrelated to H. pylori exposure, also promote host cell proliferation. We propose that H. pylori activation of a plasma membrane repair is pro-proliferative. This study might therefore provide new insight into potential mechanisms of H. pylori-induced gastric carcinogenesis.

  4. Transcription-coupled nucleotide excision repair in mammalian cells: molecular mechanisms and biological effects

    Institute of Scientific and Technical Information of China (English)

    Mafia Fousteri; Leon HF Mullenders

    2008-01-01

    The encounter of elongating RNA polymerase Ⅱ (RNAPIIo) with DNA lesions has severe consequences for the cell as this event provides a strong signal for P53-dependent apoptosis and cell cycle arrest. To counteract prolonged blockage of transcription, the cell removes the RNAPllo-hlocking DNA lesions by transcription-coupled repair (TC-NER), a specialized subpathway of nucleotide excision repair (NER). Exposure of mice to UVB light or chemicals has elucidated that TC-NER is a critical survival pathway protecting against acute toxic and long-term effects (cancer) of genotoxic exposure. Deficiency in TC-NER is associated with mutations in the CSA and CSB genes giving rise to the rare hu-man disorder Cockayne syndrome (CS). Recent data suggest that CSA and CSB play differential roles in mammalian TC-NER: CSB as a repair coupling factor to attract NER proteins, chromatin remodellers and the CSA- E3-ubiquitin iigase complex to the stalled RNAPI io. CSA is dispensable for attraction of NER proteins, yet in cooperation with CSB is required to recruit XAB2, the nucleosomal binding protein HMGNl and TFIIS. The emerging picture of TC-NER is complex: repair of transcription-blocking lesions occurs without displacement of the DNA damage-stalled RNAPIIo, and requires at least two essential assembly factors (CSA and CSB), the core NER factors (except for XPC-RAD23B), and TC-NER specific factors. These and yet unidentified proteins will accomplish not only efficient repair of transcrip-tion-blocking lesions, but are also likely to contribute to DNA damage signalling events.

  5. 5. MUTAGEN SENSITIVITY AND DNA REPAIR CAPACITY (DRC) AS RISK FACTORS FOR NON-SMALL CELL LUNG CANCER

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@An alkaline single cell gel electrophoresis assay has been standardised by which mutagen sensitivity and DNA repair capacity (DRC) can be measured in cryopreserved peripheral blood lymphocytes following induction and repair of DNA damage induced by bleomycin. In an ongoing case-control study, we have applied this assay to Caucasian

  6. Exposure of Human Lung Cells to Tobacco Smoke Condensate Inhibits the Nucleotide Excision Repair Pathway.

    Directory of Open Access Journals (Sweden)

    Nathaniel Holcomb

    Full Text Available Exposure to tobacco smoke is the number one risk factor for lung cancer. Although the DNA damaging properties of tobacco smoke have been well documented, relatively few studies have examined its effect on DNA repair pathways. This is especially true for the nucleotide excision repair (NER pathway which recognizes and removes many structurally diverse DNA lesions, including those introduced by chemical carcinogens present in tobacco smoke. The aim of the present study was to investigate the effect of tobacco smoke on NER in human lung cells. We studied the effect of cigarette smoke condensate (CSC, a surrogate for tobacco smoke, on the NER pathway in two different human lung cell lines; IMR-90 lung fibroblasts and BEAS-2B bronchial epithelial cells. To measure NER, we employed a slot-blot assay to quantify the introduction and removal of UV light-induced 6-4 photoproducts and cyclobutane pyrimidine dimers. We find a dose-dependent inhibition of 6-4 photoproduct repair in both cell lines treated with CSC. Additionally, the impact of CSC on the abundance of various NER proteins and their respective RNAs was investigated. The abundance of XPC protein, which is required for functional NER, is significantly reduced by treatment with CSC while the abundance of XPA protein, also required for NER, is unaffected. Both XPC and XPA RNA levels are modestly reduced by CSC treatment. Finally, treatment of cells with MG-132 abrogates the reduction in the abundance of XPC protein produced by treatment with CSC, suggesting that CSC enhances proteasome-dependent turnover of the protein that is mediated by ubiquitination. Together, these findings indicate that tobacco smoke can inhibit the same DNA repair pathway that is also essential for the removal of some of the carcinogenic DNA damage introduced by smoke itself, increasing the DNA damage burden of cells exposed to tobacco smoke.

  7. The effect of aging on the DNA damage and repair capacity in 2BS cells undergoing oxidative stress.

    Science.gov (United States)

    Wang, Jin-Ling; Wang, Pei-Chang

    2012-01-01

    Aging is associated with a reduction in the DNA repair capacity under oxidative stress. However, whether the DNA damage and repair capacity can be a biomarker of aging remains controversial. In this study, we demonstrated two cause-and-effect relationships, the one is between the DNA damage and repair capacity and the cellular age, another is between DNA damage and repair capacity and the level of oxidative stress in human embryonic lung fibroblasts (2BS) exposed to different doses of hydrogen peroxide (H2O2). To clarify the mechanisms of the age-related reduction in DNA damage and repair capacity, we preliminarily evaluated the expressions of six kinds of pivotal enzymes involved in the two classical DNA repair pathways. The DNA repair capacity was observed in human fibroblasts cells using the comet assay; the age-related DNA repair enzymes were selected by RT-PCR and then verified by Western blot in vitro. Results showed that the DNA repair capacity was negatively and linearly correlated with (i) cumulative population doubling (PD) levels only in the group of low concentration of hydrogen peroxide treatment, (ii) with the level of oxidative stress only in the group of young PD cells. The mRNA expression of DNA polymerase δ1 decreased substantially in senescent cells and showed negative linear-correlation with PD levels; the protein expression level was well consistent with the mRNA level. Taken together, DNA damage and repair capacity can be a biomarker of aging. Reduced expression of DNA polymerase δ1 may be responsible for the decrease of DNA repair capacity in senescent cells.

  8. Dental pulp stem cells and their potential roles in central nervous system regeneration and repair.

    Science.gov (United States)

    Young, Fraser; Sloan, Alastair; Song, Bing

    2013-11-01

    Functional recovery from injuries to the brain or spinal cord represents a major clinical challenge. The transplantation of stem cells, traditionally isolated from embryonic tissue, may help to reduce damage following such events and promote regeneration and repair through both direct cell replacement and neurotrophic mechanisms. However, the therapeutic potential of using embryonic stem/progenitor cells is significantly restricted by the availability of embryonic tissues and associated ethical issues. Populations of stem cells reside within the dental pulp, representing an alternative source of cells that can be isolated with minimal invasiveness, and thus should illicit fewer moral objections, as a replacement for embryonic/fetal-derived stem cells. Here we discuss the similarities between dental pulp stem cells (DPSCs) and the endogenous stem cells of the central nervous system (CNS) and their ability to differentiate into neuronal cell types. We also consider in vitro and in vivo studies demonstrating the ability of DPSCs to help protect against and repair neuronal damage, suggesting that dental pulp may provide a viable alternative source of stem cells for replacement therapy following CNS damage.

  9. Proteomics and transcriptomics of peripheral nerve tissue and cells unravel new aspects of the human Schwann cell repair phenotype.

    Science.gov (United States)

    Weiss, Tamara; Taschner-Mandl, Sabine; Bileck, Andrea; Slany, Astrid; Kromp, Florian; Rifatbegovic, Fikret; Frech, Christian; Windhager, Reinhard; Kitzinger, Hugo; Tzou, Chieh-Han; Ambros, Peter F; Gerner, Christopher; Ambros, Inge M

    2016-12-01

    The remarkable feature of Schwann cells (SCs) to transform into a repair phenotype turned the spotlight on this powerful cell type. SCs provide the regenerative environment for axonal re-growth after peripheral nerve injury (PNI) and play a vital role in differentiation of neuroblastic tumors into a benign subtype of neuroblastoma, a tumor originating from neural crest-derived neuroblasts. Hence, understanding their mode-of-action is of utmost interest for new approaches in regenerative medicine, but also for neuroblastoma therapy. However, literature on human SCs is scarce and it is unknown to which extent human SC cultures reflect the SC repair phenotype developing after PNI in patients. We performed high-resolution proteome profiling and RNA-sequencing on highly enriched human SC and fibroblast cultures, control and ex vivo degenerated nerve explants to identify novel molecules and functional processes active in repair SCs. In fact, we found cultured SCs and degenerated nerves to share a similar repair SC-associated expression signature, including the upregulation of JUN, as well as two prominent functions, i.e., myelin debris clearance and antigen presentation via MHCII. In addition to myelin degradation, cultured SCs were capable of actively taking up cell-extrinsic components in functional phagocytosis and co-cultivation assays. Moreover, in cultured SCs and degenerated nerve tissue MHCII was upregulated at the cellular level along with high expression of chemoattractants and co-inhibitory rather than -stimulatory molecules. These results demonstrate human SC cultures to execute an inherent program of nerve repair and support two novel repair SC functions, debris clearance via phagocytosis-related mechanisms and type II immune-regulation. GLIA 2016;64:2133-2153. © 2016 The Authors. Glia Published by Wiley Periodicals, Inc.

  10. Dicarboxylic acids with limited numbers of hydrocarbons stabilize cell membrane and increase osmotic resistance in rat erythrocytes.

    Science.gov (United States)

    Mineo, Hitoshi; Amita, Nozomi; Kawawake, Megumi; Higuchi, Ayaka

    2013-11-01

    We examined the effect of dicarboxylic acids having 0 to 6 hydrocarbons and their corresponding monocarboxylic or tricarboxylic acids in changing the osmotic fragility (OF) in rat red blood cells (RBCs). Malonic, succinic, glutaric and adipic acids, which are dicarboxylic acids with 1, 2, 3 and 4 straight hydrocarbons located between two carboxylic groups, decreased the OF in a concentration-dependent manner. Other long-chain dicarboxylic acids did not change the OF in rat RBCs. The benzoic acid derivatives, isophthalic and terephthalic acids, but not phthalic acid, decreased the OF in a concentration-dependent manner. Benzene-1,2,3-tricarboxylic acid, but not benzene-1,3,5-tricarboxylic acid, also decreased the OF in rat RBCs. On the other hand, monocarboxylic acids possessing 2 to 7 straight hydrocarbons and benzoic acid increased the OF in rat RBCs. In short-chain dicarboxylic acids, a limited number of hydrocarbons between the two carboxylic groups are thought to form a V- or U-shaped structure and interact with phospholipids in the RBC membrane. In benzene dicarboxylic and tricarboxylic acids, a part of benzene nucleus between the two carboxylic groups is thought to enter the plasma membrane and act on acyl-chain in phospholipids in the RBC membrane. For dicarboxylic and tricarboxylic acids, limited numbers of hydrocarbons in molecules are speculated to enter the RBC membrane with the hydrophilic carboxylic groups remaining outside, stabilizing the structure of the cell membrane and resulting in an increase in osmotic resistance in rat RBCs.

  11. Aryl hydrocarbon receptor-independent up-regulation of intracellular calcium concentration by environmental polycyclic aromatic hydrocarbons in human endothelial HMEC-1 cells.

    Science.gov (United States)

    Mayati, Abdullah; Le Ferrec, Eric; Lagadic-Gossmann, Dominique; Fardel, Olivier

    2012-09-01

    Polycyclic aromatic hydrocarbons (PAHs) such as benzo(a)pyrene (B(a)P) constitute a major family of widely-distributed environmental toxic contaminants, known as potent ligands of the aryl hydrocarbon receptor (AhR). B(a)P has been recently shown to trigger an early and transient increase of intracellular calcium concentration ([Ca(2+)](i)), involved in AhR-related up-regulation of target genes by B(a)P. This study was designed to determine whether AhR may play a role in [Ca(2+)](i) induction provoked by B(a)P. We demonstrated that, in addition to B(a)P, various PAHs, including pyrene and benzo(e)pyrene, known to not or only very poorly interact with AhR, similarly up-regulated [Ca(2+)](i) in human endothelial HMEC-1 cells. Moreover, α-naphthoflavone, a flavonoïd antagonist of AhR, was also able to induce [Ca(2+)](i). Knocking-down AhR expression in HMEC-1 cells through transfection of siRNAs, was finally demonstrated to not prevent B(a)P-mediated induction of [Ca(2+)](i), whereas it efficiently counteracted B(a)P-mediated induction of the referent AhR target gene cytochrome P-450 1B1. Taken together, these data demonstrate that environmental PAHs trigger [Ca(2+)](i) induction in an AhR-independent manner.

  12. Oriented cell division: new roles in guiding skin wound repair and regeneration.

    Science.gov (United States)

    Yang, Shaowei; Ma, Kui; Geng, Zhijun; Sun, Xiaoyan; Fu, Xiaobing

    2015-11-18

    Tissue morphogenesis depends on precise regulation and timely co-ordination of cell division and also on the control of the direction of cell division. Establishment of polarity division axis, correct alignment of the mitotic spindle, segregation of fate determinants equally or unequally between daughter cells, are essential for the realization of oriented cell division. Furthermore, oriented cell division is regulated by intrinsic cues, extrinsic cues and other cues, such as cell geometry and polarity. However, dysregulation of cell division orientation could lead to abnormal tissue development and function. In the present study, we review recent studies on the molecular mechanism of cell division orientation and explain their new roles in skin repair and regeneration. © 2015 Authors.

  13. Stem cells of the suture mesenchyme in craniofacial bone development, repair and regeneration.

    Science.gov (United States)

    Maruyama, Takamitsu; Jeong, Jaeim; Sheu, Tzong-Jen; Hsu, Wei

    2016-02-01

    The suture mesenchyme serves as a growth centre for calvarial morphogenesis and has been postulated to act as the niche for skeletal stem cells. Aberrant gene regulation causes suture dysmorphogenesis resulting in craniosynostosis, one of the most common craniofacial deformities. Owing to various limitations, especially the lack of suture stem cell isolation, reconstruction of large craniofacial bone defects remains highly challenging. Here we provide the first evidence for an Axin2-expressing stem cell population with long-term self-renewing, clonal expanding and differentiating abilities during calvarial development and homeostastic maintenance. These cells, which reside in the suture midline, contribute directly to injury repair and skeletal regeneration in a cell autonomous fashion. Our findings demonstrate their true identity as skeletal stem cells with innate capacities to replace the damaged skeleton in cell-based therapy, and permit further elucidation of the stem cell-mediated craniofacial skeletogenesis, leading to revealing the complex nature of congenital disease and regenerative medicine.

  14. CELL THERAPY FOR INTERVERTEBRAL DISC REPAIR: ADVANCING CELL THERAPY FROM BENCH TO CLINICS

    Science.gov (United States)

    Benneker, L.M.; Andersson, G.; Iatridis, J.C.; Sakai, D.; Härtl, R.; Ito, K.; Grad, S.

    2016-01-01

    Intervertebral disc (IVD) degeneration is a major cause of pain and disability; yet therapeutic options are limited and treatment often remains unsatisfactory. In recent years, research activities have intensified in tissue engineering and regenerative medicine, and pre-clinical studies have demonstrated encourageing results. Nonetheless, the translation of new biological therapies into clinical practice faces substantial barriers. During the symposium “Where Science meets Clinics”, sponsored by the AO Foundation and held in Davos, Switzerland, from September 5–7, 2013, hurdles for translation were outlined, and ways to overcome them were discussed. With respect to cell therapy for IVD repair, it is obvious that regenerative treatment is indicated at early stages of disc degeneration, before structural changes have occurred. It is envisaged that in the near future, screening techniques and non-invasive imageing methods will be available to detect early degenerative changes. The promises of cell therapy include a sustained effect on matrix synthesis, inflammation control, and prevention of angio- and neurogenesis. Discogenic pain, originating from “black discs” or annular injury, prevention of adjacent segment disease, and prevention of post-discectomy syndrome were identified as prospective indications for cell therapy. Before such therapy can safely and effectively be introduced into clinics, the identification of the patient population and proper standardisation of diagnostic parameters and outcome measurements are indispensable. Furthermore, open questions regarding the optimal cell type and delivery method need to be resolved in outline order to overcome the safety concerns implied with certain procedures. Finally, appropriate large animal models and well-designed clinical studies will be required, particularly addressing safety aspects. PMID:24802611

  15. Cell therapy for intervertebral disc repair: advancing cell therapy from bench to clinics

    Directory of Open Access Journals (Sweden)

    LM Benneker

    2014-05-01

    Full Text Available Intervertebral disc (IVD degeneration is a major cause of pain and disability; yet therapeutic options are limited and treatment often remains unsatisfactory. In recent years, research activities have intensified in tissue engineering and regenerative medicine, and pre-clinical studies have demonstrated encouraging results. Nonetheless, the translation of new biological therapies into clinical practice faces substantial barriers. During the symposium "Where Science meets Clinics", sponsored by the AO Foundation and held in Davos, Switzerland, from September 5-7, 2013, hurdles for translation were outlined, and ways to overcome them were discussed. With respect to cell therapy for IVD repair, it is obvious that regenerative treatment is indicated at early stages of disc degeneration, before structural changes have occurred. It is envisaged that in the near future, screening techniques and non-invasive imaging methods will be available to detect early degenerative changes. The promises of cell therapy include a sustained effect on matrix synthesis, inflammation control, and prevention of angio- and neuro-genesis. Discogenic pain, originating from "black discs" or annular injury, prevention of adjacent segment disease, and prevention of post-discectomy syndrome were identified as prospective indications for cell therapy. Before such therapy can safely and effectively be introduced into clinics, the identification of the patient population and proper standardisation of diagnostic parameters and outcome measurements are indispensable. Furthermore, open questions regarding the optimal cell type and delivery method need to be resolved in order to overcome the safety concerns implied with certain procedures. Finally, appropriate large animal models and well-designed clinical studies will be required, particularly addressing safety aspects.

  16. Mesenchymal stem cells promote incision wound repair in a mouse ...

    African Journals Online (AJOL)

    Full-thickness cutaneous wounds (4 × 2 cm) were made by incision on the dorsal side of the mice. The wound was then ..... on age as well as the type and size of injury. In .... stem cells favour healing of the cutaneous radiation syndrome in a ...

  17. Mesenchymal Stem Cells: Application for Immunomodulation and Tissue Repair

    DEFF Research Database (Denmark)

    Horwood, Nicole J.; Dazzi, Francesco; Zaher, Walid

    2012-01-01

    for differentiation and/or providing bystander support for resident stromal cells. This chapter discusses the cellular and molecular properties of MSC, the mechanisms by which they can modulate immune responses and the clinical applications of MSC in disorders such as graft-versus-host disease and aplastic anaemia...

  18. Therapeutic potential of stem cells in skin repair and regeneration

    Institute of Scientific and Technical Information of China (English)

    ZHANG Cui-ping; FU Xiao-bing

    2008-01-01

    @@ Stem cells are defined by their capacity of self-renewal and multilineage differentiation, which make them uniquely situated to treat a broad spectrum of human diseases. Based on a series of remarkable studies in several fields of regen-erative medicine, their application is not too far from the clinical practice.

  19. More efficient repair of DNA double-strand breaks in skeletal muscle stem cells compared to their committed progeny

    Directory of Open Access Journals (Sweden)

    Leyla Vahidi Ferdousi

    2014-11-01

    Full Text Available The loss of genome integrity in adult stem cells results in accelerated tissue aging and is possibly cancerogenic. Adult stem cells in different tissues appear to react robustly to DNA damage. We report that adult skeletal stem (satellite cells do not primarily respond to radiation-induced DNA double-strand breaks (DSBs via differentiation and exhibit less apoptosis compared to other myogenic cells. Satellite cells repair these DNA lesions more efficiently than their committed progeny. Importantly, non-proliferating satellite cells and post-mitotic nuclei in the fiber exhibit dramatically distinct repair efficiencies. Altogether, reduction of the repair capacity appears to be more a function of differentiation than of the proliferation status of the muscle cell. Notably, satellite cells retain a high efficiency of DSB repair also when isolated from the natural niche. Finally, we show that repair of DSB substrates is not only very efficient but, surprisingly, also very accurate in satellite cells and that accurate repair depends on the key non-homologous end-joining factor DNA-PKcs.

  20. Relationship of DNA repair processes to mutagenesis and carcinogenesis in mammalian cells. Progress report, August 1, 1977-October 31, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Evans, H.H.

    1980-10-01

    The objective of this research is to determine the role of DNA repair in mutagenesis and carcinogenesis in mammalian cells. More specifically, mutant strains will be selected which are deficient in various DNA repair pathways. These strains will be studied with regard to (1) the nature of the defect in repair, and (2) the mutability and transformability of the defective cells by various agents as compared to the wild type parental cells. The results to date include progress in the following areas: (1) determination of optimum conditions for growth and maintenance of cells and for quantitative measurement of various cellular parameters; (2) investigation of the effect of holding mutagenized cells for various periods in a density inhibited state on survival and on mutation and transformation frequencies; (3) examination of the repair capabilities of BHK cells, as compared to repair-proficient and repair-deficient human cells and excision-deficient mouse cells, as measured by the reactivation of Herpes simplex virus (HSV) treated with radiation and ethylmethane sulfonate (EMS); (4) initiation of host cell reactivation viral sucide enrichment and screening of survivors of the enrichment for sensitivity to ionizing radiation; and (5) investigation of the toxicity, mutagenicity, and carcinogenicity of various metabolites of 4-nitroquinoline-1-oxide (4-NQO). (ERB)

  1. Satellite-like cells contribute to pax7-dependent skeletal muscle repair in adult zebrafish.

    Science.gov (United States)

    Berberoglu, Michael A; Gallagher, Thomas L; Morrow, Zachary T; Talbot, Jared C; Hromowyk, Kimberly J; Tenente, Inês M; Langenau, David M; Amacher, Sharon L

    2017-04-15

    Satellite cells, also known as muscle stem cells, are responsible for skeletal muscle growth and repair in mammals. Pax7 and Pax3 transcription factors are established satellite cell markers required for muscle development and regeneration, and there is great interest in identifying additional factors that regulate satellite cell proliferation, differentiation, and/or skeletal muscle regeneration. Due to the powerful regenerative capacity of many zebrafish tissues, even in adults, we are exploring the regenerative potential of adult zebrafish skeletal muscle. Here, we show that adult zebrafish skeletal muscle contains cells similar to mammalian satellite cells. Adult zebrafish satellite-like cells have dense heterochromatin, express Pax7 and Pax3, proliferate in response to injury, and show peak myogenic responses 4-5 days post-injury (dpi). Furthermore, using a pax7a-driven GFP reporter, we present evidence implicating satellite-like cells as a possible source of new muscle. In lieu of central nucleation, which distinguishes regenerating myofibers in mammals, we describe several characteristics that robustly identify newly-forming myofibers from surrounding fibers in injured adult zebrafish muscle. These characteristics include partially overlapping expression in satellite-like cells and regenerating myofibers of two RNA-binding proteins Rbfox2 and Rbfoxl1, known to regulate embryonic muscle development and function. Finally, by analyzing pax7a; pax7b double mutant zebrafish, we show that Pax7 is required for adult skeletal muscle repair, as it is in the mouse.

  2. DNA Damage Follows Repair Factor Depletion and Portends Genome Variation in Cancer Cells after Pore Migration.

    Science.gov (United States)

    Irianto, Jerome; Xia, Yuntao; Pfeifer, Charlotte R; Athirasala, Avathamsa; Ji, Jiazheng; Alvey, Cory; Tewari, Manu; Bennett, Rachel R; Harding, Shane M; Liu, Andrea J; Greenberg, Roger A; Discher, Dennis E

    2017-01-23

    Migration through micron-size constrictions has been seen to rupture the nucleus, release nuclear-localized GFP, and cause localized accumulations of ectopic 53BP1-a DNA repair protein. Here, constricted migration of two human cancer cell types and primary mesenchymal stem cells (MSCs) increases DNA breaks throughout the nucleoplasm as assessed by endogenous damage markers and by electrophoretic "comet" measurements. Migration also causes multiple DNA repair proteins to segregate away from DNA, with cytoplasmic mis-localization sustained for many hours as is relevant to delayed repair. Partial knockdown of repair factors that also regulate chromosome copy numbers is seen to increase DNA breaks in U2OS osteosarcoma cells without affecting migration and with nucleoplasmic patterns of damage similar to constricted migration. Such depletion also causes aberrant levels of DNA. Migration-induced nuclear damage is nonetheless reversible for wild-type and sub-cloned U2OS cells, except for lasting genomic differences between stable clones as revealed by DNA arrays and sequencing. Gains and losses of hundreds of megabases in many chromosomes are typical of the changes and heterogeneity in bone cancer. Phenotypic differences that arise from constricted migration of U2OS clones are further illustrated by a clone with a highly elongated and stable MSC-like shape that depends on microtubule assembly downstream of the transcription factor GATA4. Such changes are consistent with reversion to a more stem-like state upstream of cancerous osteoblastic cells. Migration-induced genomic instability can thus associate with heritable changes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. The Aryl Hydrocarbon Receptor Governs Epithelial Cell Invasion during Oropharyngeal Candidiasis

    Science.gov (United States)

    Solis, Norma V.; Swidergall, Marc; Bruno, Vincent M.; Gaffen, Sarah L.

    2017-01-01

    ABSTRACT Oropharyngeal candidiasis (OPC), caused predominantly by Candida albicans, is a prevalent infection in patients with advanced AIDS, defects in Th17 immunity, and head and neck cancer. A characteristic feature of OPC is fungal invasion of the oral epithelial cells. One mechanism by which C. albicans hyphae can invade oral epithelial cells is by expressing the Als3 and Ssa1 invasins that interact with the epidermal growth factor receptor (EGFR) on epithelial cells and stimulate endocytosis of the organism. However, the signaling pathways that function downstream of EGFR and mediate C. albicans endocytosis are poorly defined. Here, we report that C. albicans infection activates the aryl hydrocarbon receptor (AhR), leading to activation of Src family kinases (SFKs), which in turn phosphorylate EGFR and induce endocytosis of the fungus. Furthermore, treatment of oral epithelial cells with interferon gamma inhibits fungal endocytosis by inducing the synthesis of kynurenines, which cause prolonged activation of AhR and SFKs, thereby interfering with C. albicans-induced EGFR signaling. Treatment of both immunosuppressed and immunocompetent mice with an AhR inhibitor decreases phosphorylation of SFKs and EGFR in the oral mucosa, reduces fungal invasion, and lessens the severity of OPC. Thus, our data indicate that AhR plays a central role in governing the pathogenic interactions of C. albicans with oral epithelial cells during OPC and suggest that this receptor is a potential therapeutic target. PMID:28325761

  4. Sternal Repair with Bone Grafts Engineered from Amniotic Mesenchymal Stem Cells

    Science.gov (United States)

    Steigman, Shaun A.; Ahmed, Azra; Shanti, Rabie M.; Tuan, Rocky S.; Valim, Clarissa; Fauza, Dario O.

    2013-01-01

    Background We aimed at determining whether osseous grafts engineered from amniotic mesenchymal stem cells (aMSCs) could be employed in postnatal sternal repair. Methods Leporine aMSCs were isolated, identified, transfected with green fluorescent protein (GFP), expanded, and seeded onto biodegradable electrospun nanofibrous scaffolds (n=6). Constructs were dynamically maintained in an osteogenic medium and equally divided into two groups with respect to time in vitro, namely 14.6 or 33.9 weeks. They were then used to repair full thickness sternal defects spanning 2–3 intercostal spaces in allogeneic kits (n=6). Grafts were submitted to multiple analyses 2 months thereafter. Results Chest roentgenograms showed defect closure in all animals, confirmed at necropsy. Graft density as assessed by micro-CT scans increased significantly in vivo, yet there were no differences in mineralization by extracellular calcium measurements pre- and post-implantation. There was a borderline increase in alkaline phosphatase activity in vivo, suggesting ongoing graft remodeling. Histologically, implants contained GFP-positive cells and few mononuclear infiltrates. There were no differences between the two construct groups in any comparison. Conclusions Engineered osseous grafts derived from amniotic mesenchymal stem cells may become a viable alternative for sternal repair. The amniotic fluid can be a practical cell source for engineered chest wall reconstruction. PMID:19524727

  5. Transcription inhibition by DRB potentiates recombinational repair of UV lesions in mammalian cells.

    Directory of Open Access Journals (Sweden)

    Ivaylo Stoimenov

    Full Text Available Homologous recombination (HR is intricately associated with replication, transcription and DNA repair in all organisms studied. However, the interplay between all these processes occurring simultaneously on the same DNA molecule is still poorly understood. Here, we study the interplay between transcription and HR during ultraviolet light (UV-induced DNA damage in mammalian cells. Our results show that inhibition of transcription with 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB increases the number of UV-induced DNA lesions (γH2AX, 53BP1 foci formation, which correlates with a decrease in the survival of wild type or nucleotide excision repair defective cells. Furthermore, we observe an increase in RAD51 foci formation, suggesting HR is triggered in response to an increase in UV-induced DSBs, while inhibiting transcription. Unexpectedly, we observe that DRB fails to sensitise HR defective cells to UV treatment. Thus, increased RAD51 foci formation correlates with increased cell death, suggesting the existence of a futile HR repair of UV-induced DSBs which is linked to transcription inhibition.

  6. Induced pluripotent stem (iPS) cells repair and regenerate infarcted myocardium.

    Science.gov (United States)

    Singla, Dinender K; Long, Xilin; Glass, Carley; Singla, Reetu D; Yan, Binbin

    2011-10-03

    Cardiac myocyte differentiation reported thus far is from iPS cells generated from mouse and human fibroblasts. However, there is no article on the generation of iPS cells from cardiac ventricular specific cell types such as H9c2 cells. Therefore, whether transduced H9c2 cells, originally isolated from embryonic cardiac ventricular tissue, will be able to generate iPS cells and have the potential to repair and regenerate infarcted myocardium remains completely elusive. We transduced H9c2 cells with four stemness factors, Oct3/4, Sox2, Klf4, and c-Myc, and successfully reprogrammed them into iPS cells. These iPS cells were able to differentiate into beating cardiac myocytes and positively stained for cardiac specific sarcomeric α-actin and myosin heavy chain proteins. Following transplantation in the infarcted myocardium, there were newly differentiated cardiac myocytes and formation of gap junction proteins at 2 weeks post-myocardial infarction (MI), suggesting newly formed cardiac myocytes were integrated into the native myocardium. Furthermore, transplanted iPS cells significantly (p cell groups. Moreover, our iPS cell derived cardiac myocyte differentiation in vitro and in vivo was comparable to embryonic stem cells in the present study. In conclusion we report for the first time that we have H9c2 cell-derived iPS cells which contain the potential to differentiate into cardiac myocytes in the cell culture system and repair and regenerate infarcted myocardium with improved cardiac function in vivo.

  7. Assessment of the aryl hydrocarbon receptor-mediated activities of polycyclic aromatic hydrocarbons in a human cell-based reporter gene assay.

    Science.gov (United States)

    Vondráček, Jan; Pěnčíková, Kateřina; Neča, Jiří; Ciganek, Miroslav; Grycová, Aneta; Dvořák, Zdeněk; Machala, Miroslav

    2017-01-01

    Activation of the aryl hydrocarbon receptor (AhR)-mediated activity is one of key events in toxicity of polycyclic aromatic hydrocarbons (PAHs). Although various classes of AhR ligands may differentially activate human and rodent AhR, there is presently a lack of data on the human AhR-inducing relative potencies (REPs) of PAHs. Here, we focused on estimation of the AhR-mediated activities of a large set of environmental PAHs in human gene reporter AZ-AhR cell line, with an aim to develop the human AhR-based REP values with potential implications for risk assessment of PAHs. The previously identified weakly active PAHs mostly failed to activate the AhR in human cells. The order for REPs of individual PAHs in human cells largely corresponded with the available data from rodent-based experimental systems; nevertheless, we identified differences up to one order of magnitude in REP values of PAHs between human and rodent cells. Higher REP values were found in human cells for some important environmental contaminants or suspected carcinogens, such as indeno[1,2,3-cd]pyrene, benz[a]anthracene or benzo[b]fluoranthene, while lower REP values were determined for methyl-substituted PAHs. Our results also indicate that a different rate of metabolism for individual PAHs in human vs. rodent cells may affect estimation of REP values in human cell-based assay, and potentially alter toxicity of some compounds, such as benzofluoranthenes, in humans. We applied the AZ-AhR assay to evaluation of the AhR-mediated activity of complex mixtures of organic compounds associated with diesel exhaust particles, and we identified the polar compounds present in these mixtures as being particularly highly active in human cells, as compared with rodent cells. The present data suggest that differences may exist between the AhR-mediated potencies of PAHs in human and rodent cells, and that the AhR-mediated effects of polar PAH derivatives and metabolites in human cell models deserve further

  8. Prolonged particulate chromate exposure does not inhibit homologous recombination repair in North Atlantic right whale (Eubalaena glacialis) lung cells.

    Science.gov (United States)

    Browning, Cynthia L; Wise, Catherine F; Wise, John Pierce

    2017-09-15

    Chromosome instability is a common feature of cancers that forms due to the misrepair of DNA double strand breaks. Homologous recombination (HR) repair is a high fidelity DNA repair pathway that utilizes a homologous DNA sequence to accurately repair such damage and protect the genome. Prolonged exposure (>72h) to the human lung carcinogen, particulate hexavalent chromium (Cr(VI)), inhibits HR repair, resulting in increased chromosome instability in human cells. Comparative studies have shown acute Cr(VI) exposure induces less chromosome damage in whale cells than human cells, suggesting investigating the effect of this carcinogen in other species may inform efforts to prevent Cr(VI)-induced chromosome instability. Thus, the goal of this study was to determine the effect of prolonged Cr(VI) exposure on HR repair and clastogenesis in North Atlantic right whale (Eubalaena glacialis) lung cells. We show particulate Cr(VI) induces HR repair activity after both acute (24h) and prolonged (120h) exposure in North Atlantic right whale cells. Although the RAD51 response was lower following prolonged Cr(VI) exposure compared to acute exposure, the response was sufficient for HR repair to occur. In accordance with active HR repair, no increase in Cr(VI)-induced clastogenesis was observed with increased exposure time. These results suggest prolonged Cr(VI) exposure affects HR repair and genomic stability differently in whale and human lung cells. Future investigation of the differences in how human and whale cells respond to chemical carcinogens may provide valuable insight into mechanisms of preventing chemical carcinogenesis. Copyright © 2017. Published by Elsevier Inc.

  9. The battle of the bulge: re-evaluating hair follicle stem cells in wound repair.

    Science.gov (United States)

    Garcin, Clare L; Ansell, David M

    2017-02-01

    The hair follicle has an established role in wound re-epithelialisation, a phenomenon that has been appreciated since at least the first half of the last century. The bulge niche, one location of hair follicle epithelial stem cells has been of particular interest to researchers over recent years, with numerous studies showing its ability to directly contribute to epidermal repair. However, recent work has highlighted other progenitor regions of the hair follicle that appear to act as stem cells during epidermal repair. In addition, several studies within the last 12 months have questioned the importance of the bulge during re-epithelialisation, producing conflicting literature. Here we provide a new model to demonstrate how several important differences in experimental design between studies could account for these seemingly opposing findings, which may have implications for how future studies are conducted.

  10. Human Cardiac Tissue Engineering: From Pluripotent Stem Cells to Heart Repair

    Science.gov (United States)

    Jackman, Christopher P.; Shadrin, Ilya Y.; Carlson, Aaron L.; Bursac, Nenad

    2014-01-01

    Engineered cardiac tissues hold great promise for use in drug and toxicology screening, in vitro studies of human physiology and disease, and as transplantable tissue grafts for myocardial repair. In this review, we discuss recent progress in cell-based therapy and functional tissue engineering using pluripotent stem cell-derived cardiomyocytes and we describe methods for delivery of cells into the injured heart. While significant hurdles remain, notable advances have been made in the methods to derive large numbers of pure human cardiomyocytes, mature their phenotype, and produce and implant functional cardiac tissues, bringing the field a step closer to widespread in vitro and in vivo applications. PMID:25599018

  11. Role of bone marrow mesenchymal stem cells in repair of neural cell injury induced by okadaic acid

    Directory of Open Access Journals (Sweden)

    Jia-jing LIU

    2017-06-01

    Full Text Available Objective To study whether the human bone marrow mesenchymal stem cells (HBMSCs can repair damaged neural cells induced by okadaic acid (OA. Methods Neuroblastoma cell line SH-SY5Y cells were used to incubate with 20nmol/L okadaic acid for 24h, establishing Alzheimer's Disease cell model; Three groups were set up: normal group, okadaic acid -damaged (OA-damaged group, hBMSCs -treatment group. The cells were injured for 24h with 20nmol/L OA in OA-damaged group, and treated with conditioned medium obtaining hBMSCs for 24h after 24h OA injury in the treatment group. Then CCK-8 was used for detecting cell vitality, immune fluorescence dyed microtubules and microfilaments for determining the dendritic cell length and fluorescence intensity, in addition, Western blotting for analyzing the protein level of phosphorylated tau and total tau proteins. Results Okadaic acid damaged SH-SY5Y cells, contributed to shrinkage, collapse, cavitation of the SH-SY5Y cell body, dendritic shortening and fracture, and irregular arrangement of microtubule microfilaments; while BMSCs conditioned medium made SH- SY5Y cell body become round and longer, dendrites restored, and microtubules and microfilaments arranged regularly, fluorescence intensity enhanced. Meanwhile,it also down-regulated the level of OA-induced tau phosphorylation. Conclusion hBMSCs have repair effects on the neural cell damage induced by okadaic acid. DOI: 10.11855/j.issn.0577-7402.2017.05.04

  12. Enhanced infarct myocardium repair mediated by thermosensitive copolymer hydrogel-based stem cell transplantation

    OpenAIRE

    Xia, Yu; Zhu, Kai; Lai, Hao; Lang, Meidong; Xiao, Yan; Lian, Sheng; Guo, Changfa; Wang, Chunsheng

    2015-01-01

    Mesenchymal stem cell (MSC) transplantation by intramyocardial injection has been proposed as a promising therapy strategy for cardiac repair after myocardium infarction. However, low retention and survival of grafted MSCs hinder its further application. In this study, copolymer with N-isopropylacrylamide/acrylic acid/2-hydroxylethyl methacrylate-poly(ɛ-caprolactone) ratio of 88:9.6:2.4 was bioconjugated with type I collagen to construct a novel injectable thermosensitive hydrogel. The inject...

  13. Modulation of Wound Healing and Scar Formation by MG53 Protein-mediated Cell Membrane Repair*

    Science.gov (United States)

    Li, Haichang; Duann, Pu; Lin, Pei-Hui; Zhao, Li; Fan, Zhaobo; Tan, Tao; Zhou, Xinyu; Sun, Mingzhai; Fu, Minghuan; Orange, Matthew; Sermersheim, Matthew; Ma, Hanley; He, Duofen; Steinberg, Steven M.; Higgins, Robert; Zhu, Hua; John, Elizabeth; Zeng, Chunyu; Guan, Jianjun; Ma, Jianjie

    2015-01-01

    Cell membrane repair is an important aspect of physiology, and disruption of this process can result in pathophysiology in a number of different tissues, including wound healing, chronic ulcer and scarring. We have previously identified a novel tripartite motif family protein, MG53, as an essential component of the cell membrane repair machinery. Here we report the functional role of MG53 in the modulation of wound healing and scarring. Although MG53 is absent from keratinocytes and fibroblasts, remarkable defects in skin architecture and collagen overproduction are observed in mg53−/− mice, and these animals display delayed wound healing and abnormal scarring. Recombinant human MG53 (rhMG53) protein, encapsulated in a hydrogel formulation, facilitates wound healing and prevents scarring in rodent models of dermal injuries. An in vitro study shows that rhMG53 protects against acute injury to keratinocytes and facilitates the migration of fibroblasts in response to scratch wounding. During fibrotic remodeling, rhMG53 interferes with TGF-β-dependent activation of myofibroblast differentiation. The resulting down-regulation of α smooth muscle actin and extracellular matrix proteins contributes to reduced scarring. Overall, these studies establish a trifunctional role for MG53 as a facilitator of rapid injury repair, a mediator of cell migration, and a modulator of myofibroblast differentiation during wound healing. Targeting the functional interaction between MG53 and TGF-β signaling may present a potentially effective means for promoting scarless wound healing. PMID:26306047

  14. Analysis of DNA Double-strand Break (DSB) Repair in Mammalian Cells

    Science.gov (United States)

    Seluanov, Andrei; Mao, Zhiyong; Gorbunova, Vera

    2010-01-01

    DNA double-strand breaks are the most dangerous DNA lesions that may lead to massive loss of genetic information and cell death. Cells repair DSBs using two major pathways: nonhomologous end joining (NHEJ) and homologous recombination (HR). Perturbations of NHEJ and HR are often associated with premature aging and tumorigenesis, hence it is important to have a quantitative way of measuring each DSB repair pathway. Our laboratory has developed fluorescent reporter constructs that allow sensitive and quantitative measurement of NHEJ and HR. The constructs are based on an engineered GFP gene containing recognition sites for a rare-cutting I-SceI endonuclease for induction of DSBs. The starting constructs are GFP negative as the GFP gene is inactivated by an additional exon, or by mutations. Successful repair of the I-SceI-induced breaks by NHEJ or HR restores the functional GFP gene. The number of GFP positive cells counted by flow cytometry provides quantitative measure of NHEJ or HR efficiency. PMID:20864925

  15. Analysis of DNA double-strand break (DSB) repair in mammalian cells.

    Science.gov (United States)

    Seluanov, Andrei; Mao, Zhiyong; Gorbunova, Vera

    2010-09-08

    DNA double-strand breaks are the most dangerous DNA lesions that may lead to massive loss of genetic information and cell death. Cells repair DSBs using two major pathways: nonhomologous end joining (NHEJ) and homologous recombination (HR). Perturbations of NHEJ and HR are often associated with premature aging and tumorigenesis, hence it is important to have a quantitative way of measuring each DSB repair pathway. Our laboratory has developed fluorescent reporter constructs that allow sensitive and quantitative measurement of NHEJ and HR. The constructs are based on an engineered GFP gene containing recognition sites for a rare-cutting I-SceI endonuclease for induction of DSBs. The starting constructs are GFP negative as the GFP gene is inactivated by an additional exon, or by mutations. Successful repair of the I-SceI-induced breaks by NHEJ or HR restores the functional GFP gene. The number of GFP positive cells counted by flow cytometry provides quantitative measure of NHEJ or HR efficiency.

  16. Hydrocarbon fuel processing of micro solid oxide fuel cell systems[Dissertation 17455

    Energy Technology Data Exchange (ETDEWEB)

    Stutz, M. J.

    2007-07-01

    The scope of this thesis is the numerical and experimental investigation of the fuel processing of a micro solid oxide fuel cell (SOFC) running on hydrocarbon fuel. The goal is to enhance the overall system efficiency by optimization of the reforming process in the steady state and the improvement of the start-up process. Micro SOFC are a potential alternative to the currently used batteries in portable devices. Liquid butane in a cartridge could be the energy source. This dissertation is focused on the fuel processing of the system, namely the reforming and post-combusting processes. The reformer converts the hydrocarbon fuel to a hydrogen rich gas that can be utilized by the SOFC. The post-combustor depletes the toxic and/or explosive gases before leaving the exhaust. Chapter One presents a short introduction to the field of hydrocarbon fuel processing in micro solid oxide fuel cell systems, the next three chapters deal with computational modeling of the transport phenomena inside a micro-reformer, which leads to a better understanding of the chemistry and the physics therein, hence progress in the design and operation parameters. The experimental part (i.e. Chapter Five) of this thesis focuses on the feasibility of a novel hybrid start-up method of a fuel cell system that employs existing components as an additional heat source. In Chapter Two the effect of wall heat conduction on the syngas (hydrogen and carbon monoxide) production of a micro-reformer, representing micro-fabricated channels or monoliths, is investigated. Methane is used as a model hydrocarbon fuel since its heterogeneous reaction path on rhodium is known and validated. The simulations demonstrate that the axial wall conduction strongly influences the performance of the micro-reformer and should not be neglected without a careful a priori investigation of its impact. Methane conversion and hydrogen yield are strongly dependent of the wall inner surface temperature, which is influenced by the

  17. Hydrocarbon fuel processing of micro solid oxide fuel cell systems[Dissertation 17455

    Energy Technology Data Exchange (ETDEWEB)

    Stutz, M. J.

    2007-07-01

    The scope of this thesis is the numerical and experimental investigation of the fuel processing of a micro solid oxide fuel cell (SOFC) running on hydrocarbon fuel. The goal is to enhance the overall system efficiency by optimization of the reforming process in the steady state and the improvement of the start-up process. Micro SOFC are a potential alternative to the currently used batteries in portable devices. Liquid butane in a cartridge could be the energy source. This dissertation is focused on the fuel processing of the system, namely the reforming and post-combusting processes. The reformer converts the hydrocarbon fuel to a hydrogen rich gas that can be utilized by the SOFC. The post-combustor depletes the toxic and/or explosive gases before leaving the exhaust. Chapter One presents a short introduction to the field of hydrocarbon fuel processing in micro solid oxide fuel cell systems, the next three chapters deal with computational modeling of the transport phenomena inside a micro-reformer, which leads to a better understanding of the chemistry and the physics therein, hence progress in the design and operation parameters. The experimental part (i.e. Chapter Five) of this thesis focuses on the feasibility of a novel hybrid start-up method of a fuel cell system that employs existing components as an additional heat source. In Chapter Two the effect of wall heat conduction on the syngas (hydrogen and carbon monoxide) production of a micro-reformer, representing micro-fabricated channels or monoliths, is investigated. Methane is used as a model hydrocarbon fuel since its heterogeneous reaction path on rhodium is known and validated. The simulations demonstrate that the axial wall conduction strongly influences the performance of the micro-reformer and should not be neglected without a careful a priori investigation of its impact. Methane conversion and hydrogen yield are strongly dependent of the wall inner surface temperature, which is influenced by the

  18. A mutation-promotive role of nucleotide excision repair in cell cycle-arrested cell populations following UV irradiation.

    Science.gov (United States)

    Heidenreich, Erich; Eisler, Herfried; Lengheimer, Theresia; Dorninger, Petra; Steinboeck, Ferdinand

    2010-01-01

    Growing attention is paid to the concept that mutations arising in stationary, non-proliferating cell populations considerably contribute to evolution, aging, and pathogenesis. If such mutations are beneficial to the affected cell, in the sense of allowing a restart of proliferation, they are called adaptive mutations. In order to identify cellular processes responsible for adaptive mutagenesis in eukaryotes, we study frameshift mutations occurring during auxotrophy-caused cell cycle arrest in the model organism Saccharomyces cerevisiae. Previous work has shown that an exposure of cells to UV irradiation during prolonged cell cycle arrest resulted in an increased incidence of mutations. In the present work, we determined the influence of defects in the nucleotide excision repair (NER) pathway on the incidence of UV-induced adaptive mutations in stationary cells. The mutation frequency was decreased in Rad16-deficient cells and further decreased in Rad16/Rad26 double-deficient cells. A knockout of the RAD14 gene, the ortholog of the human XPA gene, even resulted in a nearly complete abolishment of UV-induced mutagenesis in cell cycle-arrested cells. Thus, the NER pathway, responsible for a normally accurate repair of UV-induced DNA damage, paradoxically is required for the generation and/or fixation of UV-induced frameshift mutations specifically in non-replicating cells.

  19. Proceedings of the workshop on hydrocarbon processing mixing and scale-up problems. [Fuels processing for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gabor, J. D. [ed.

    1978-01-01

    A workshop was convened by the Division of Fossil Fuel Utilization of the US Department of Energy in cooperation with the Particulate and Multiphase Process Program of the National Science Foundation to identify needs for fundamental engineering support for the design of chemical reactors for processing heavy hydrocarbon liquids. The problems associated with dispersing liquid hydrocarbons in a reacting gas and mixing within the gas phase are of primary concern. The transactions of the workshop begin with an introduction to the immediate goals of the Department of Energy. Fuel cell systems and current research and development are reviewed. Modeling of combustion and the problems of soot formation and deposits in hydrocarbon fuels are next considered. The fluid mechanics of turbulent mixing and its effect on chemical reactions are then presented. Current experimental work and process development provide an update on the present state-of-the-art.

  20. Insulin like growth factor 2 regulation of aryl hydrocarbon receptor in MCF-7 breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Tomblin, Justin K.; Salisbury, Travis B., E-mail: salisburyt@marshall.edu

    2014-01-17

    Highlights: •IGF-2 stimulates concurrent increases in AHR and CCND1 expression. •IGF-2 promotes the binding of AHR to the endogenous cyclin D1 promoter. •AHR knockdown inhibits IGF-2 stimulated increases in CCND1 mRNA and protein. •AHR knockdown inhibits IGF-2 stimulated increases in MCF-7 proliferation. -- Abstract: Insulin like growth factor (IGF)-1 and IGF-2 stimulate normal growth, development and breast cancer cell proliferation. Cyclin D1 (CCND1) promotes cell cycle by inhibiting retinoblastoma protein (RB1). The aryl hydrocarbon receptor (AHR) is a major xenobiotic receptor that also regulates cell cycle. The purpose of this study was to investigate whether IGF-2 promotes MCF-7 breast cancer proliferation by inducing AHR. Western blot and quantitative real time PCR (Q-PCR) analysis revealed that IGF-2 induced an approximately 2-fold increase (P < .001) in the expression of AHR and CCND1. Chromatin immunoprecipitation (ChIP), followed by Q-PCR indicated that IGF-2 promoted (P < .001) a 7-fold increase in AHR binding on the CCND1 promoter. AHR knockdown significantly (P < .001) inhibited IGF-2 stimulated increases in CCND1 mRNA and protein. AHR knockdown cells were less (P < .001) responsive to the proliferative effects of IGF-2 than control cells. Collectively, our findings have revealed a new regulatory mechanism by which IGF-2 induction of AHR promotes the expression of CCND1 and the proliferation of MCF-7 cells. This previously uncharacterized pathway could be important for the proliferation of IGF responsive cancer cells that also express AHR.

  1. Altered Gene Expressions and Cytogenetic Repair Efficiency in Cells with Suppressed Expression of XPA after Proton Exposure

    Science.gov (United States)

    Zhang, Ye; Rohde, Larry H.; Gridley, Daila S.; Mehta, Satish K.; Pierson, Duane L.; Wu, Honglu

    2009-01-01

    Cellular responses to damages from ionizing radiation (IR) exposure are influenced not only by the genes involved in DNA double strand break (DSB) repair, but also by non- DSB repair genes. We demonstrated previously that suppressed expression of several non-DSB repair genes, such as XPA, elevated IR-induced cytogenetic damages. In the present study, we exposed human fibroblasts that were treated with control or XPA targeting siRNA to 250 MeV protons (0 to 4 Gy), and analyzed chromosome aberrations and expressions of genes involved in DNA repair. As expected, after proton irradiation, cells with suppressed expression of XPA showed a significantly elevated frequency of chromosome aberrations compared with control siRNA treated (CS) cells. Protons caused more severe DNA damages in XPA knock-down cells, as 36% cells contained multiple aberrations compared to 25% in CS cells after 4Gy proton irradiation. Comparison of gene expressions using the real-time PCR array technique revealed that expressions of p53 and its regulated genes in irradiated XPA suppressed cells were altered similarly as in CS cells, suggesting that the impairment of IR induced DNA repair in XPA suppressed cells is p53-independent. Except for XPA, which was more than 2 fold down regulated in XPA suppressed cells, several other DNA damage sensing and repair genes (GTSE1, RBBP8, RAD51, UNG and XRCC2) were shown a more than 1.5 fold difference between XPA knock-down cells and CS cells after proton exposure. The possible involvement of these genes in the impairment of DNA repair in XPA suppressed cells will be further investigated.

  2. Radiosensitivity and capacity for radiation-induced sublethal damage repair of canine transitional cell carcinoma (TCC) cell lines.

    Science.gov (United States)

    Parfitt, S L; Milner, R J; Salute, M E; Hintenlang, D E; Farese, J P; Bacon, N J; Bova, F J; Rajon, D A; Lurie, D M

    2011-09-01

    Understanding the inherent radiosensitivity and repair capacity of canine transitional cell carcinoma (TCC) can aid in optimizing radiation protocols to treat this disease. The objective of this study was to evaluate the parameters surviving fraction at 2 Gy (SF(2) ), α/β ratio and capacity for sublethal damage repair (SLDR) in response to radiation. Dose-response and split-dose studies were performed using the clonogenic assay. The mean SF(2) for three established TCC cell lines was high at 0.61. All the three cell lines exhibited a low to moderate α/β ratio, with the mean being 3.27. Two cell lines exhibited statistically increased survival at 4 and 24 h in the dose-response assay. Overall, our results indicate that the cell lines are moderately radioresistant, have a high repair capacity and behave similarly to a late-responding normal tissue. These findings indicate that the radiation protocols utilizing higher doses with less fractionation may be more effective for treating TCC.

  3. Modeling nucleotide excision repair and its impact on UV-induced mutagenesis during SOS-response in bacterial cells.

    Science.gov (United States)

    Bugay, Aleksandr N; Krasavin, Evgeny A; Parkhomenko, Aleksandr Yu; Vasilyeva, Maria A

    2015-01-01

    A model of the UV-induced mutation process in Escherichia coli bacteria has been developed taking into account the whole sequence of molecular events starting from initial photo-damage and finishing with the fixation of point mutations. The wild-type phenotype bacterial cells are compared with UV-sensitive repair-deficient mutant cells. Attention is mainly paid to excision repair system functioning as regards induced mutagenesis.

  4. Early steps in the DNA base excision/single-strand interruption repair pathway in mammalian cells

    Institute of Scientific and Technical Information of China (English)

    Muralidhar L Hegde; Tapas K Hazra; Sankar Mitra

    2008-01-01

    Base excision repair (BER) is an evolutionarily conserved process for maintaining genomic integrity by eliminating several dozen damaged (oxidized or alkylated) or inappropriate bases that are generated endogenously or induced by genotoxicants, predominantly, reactive oxygen species (ROS). BER involves 4-5 steps starting with base excision by a DNA glycosylase, followed by a common pathway usually involving an AP-endonuclease (APE) to generate 3' OH terminus at the damage site, followed by repair synthesis with a DNA polymerase and nick sealing by a DNA ligase. This pathway is also responsible for repairing DNA single-strand breaks with blocked termini directly generated by ROS. Nearly all glycosylases, far fewer than their substrate lesions particularly for oxidized bases, have broad and overlapping substrate range, and could serve as back-up enzymes in vivo. In contrast, mammalian cells encode only one APE, APEl, unlike two APEs in lower organisms. In spite of overall similarity, BER with distinct subpathways in the mammals is more complex than in E.coli. The glycosylases form complexes with downstream proteins to carry out efficient repair via distinct subpathways one of which, responsible for repair of strand breaks with 3' phosphate ter-mini generated by the NEIL family glycosylases or by ROS, requires the phosphatase activity of polynucleotide kinase instead of APEl. Different complexes may utilize distinct DNA polymerases and ligases. Mammalian glycosylases have nonconserved extensions at one of the termini, dispensable for enzymatic activity but needed for interaction with other BER and non-BER proteins for complex formation and organelle targeting. The mammalian enzymes are sometimes covalently modified which may affect activity and complex formation. The focus of this review is on the early steps in mammalian BER for oxidized damage.

  5. DNA Repair Gene Polymorphisms in Relation to Non-Small Cell Lung Cancer Survival

    Directory of Open Access Journals (Sweden)

    Yuliang Su

    2015-07-01

    Full Text Available Background: Single nucleotide polymorphisms (SNPs in the DNA repair genes are suspected to be related to the survival of lung cancer patients due to their possible influence on DNA repair capacity (DRC. However, the study results are inconsistent. Methods: A follow-up study of 610 non-small cell lung cancer (NSCLC patients was conducted to investigate genetic polymorphisms associated with the DNA repair genes in relation to NSCLC survival; 6 SNPs were genotyped, including XRCC1 (rs25487 G>A, hOGG1 (rs1052133 C>G, MUTYH (rs3219489 G>C, XPA (rs1800975 G>A, ERCC2 (rs1799793 G>A and XRCC3 (rs861539 C>T. Kaplan-Meier survival curve and Cox proportional hazards regression analyses were performed. SNP-SNP interaction was also examined using the survival tree analysis. Results: Advanced disease stage and older age at diagnosis were associated with poor prognosis of NSCLC. Patients with the variant ‘G' allele of hOGG1 rs1052133 had poor overall survival compared with those with the homozygous wild ‘CC' genotype, especially in female patients, adenocarcinoma histology, early stage, light smokers and without family history of cancer. For never smoking female lung cancer patients, individuals carrying homozygous variant ‘AA' genotype of XPA had shorter survival time compared to those with wild ‘G' alleles. Furthermore, females carrying homozygous variant XPA and hOGG1 genotypes simultaneously had 2.78-fold increased risk for death. Among all 6 polymorphisms, the homozygous variant ‘AA' of XPA carriers had poor prognosis compared to the carriers of wild ‘G' alleles of XPA together with other base excision repair (BER polymorphisms. Conclusions: Besides disease stage and age, the study found DNA repair gene polymorphisms were associated with lung cancer survival.

  6. Cell-autonomous progeroid changes in conditional mouse models for repair endonuclease XPG deficiency.

    Directory of Open Access Journals (Sweden)

    Sander Barnhoorn

    2014-10-01

    Full Text Available As part of the Nucleotide Excision Repair (NER process, the endonuclease XPG is involved in repair of helix-distorting DNA lesions, but the protein has also been implicated in several other DNA repair systems, complicating genotype-phenotype relationship in XPG patients. Defects in XPG can cause either the cancer-prone condition xeroderma pigmentosum (XP alone, or XP combined with the severe neurodevelopmental disorder Cockayne Syndrome (CS, or the infantile lethal cerebro-oculo-facio-skeletal (COFS syndrome, characterized by dramatic growth failure, progressive neurodevelopmental abnormalities and greatly reduced life expectancy. Here, we present a novel (conditional Xpg-/- mouse model which -in a C57BL6/FVB F1 hybrid genetic background- displays many progeroid features, including cessation of growth, loss of subcutaneous fat, kyphosis, osteoporosis, retinal photoreceptor loss, liver aging, extensive neurodegeneration, and a short lifespan of 4-5 months. We show that deletion of XPG specifically in the liver reproduces the progeroid features in the liver, yet abolishes the effect on growth or lifespan. In addition, specific XPG deletion in neurons and glia of the forebrain creates a progressive neurodegenerative phenotype that shows many characteristics of human XPG deficiency. Our findings therefore exclude that both the liver as well as the neurological phenotype are a secondary consequence of derailment in other cell types, organs or tissues (e.g. vascular abnormalities and support a cell-autonomous origin caused by the DNA repair defect itself. In addition they allow the dissection of the complex aging process in tissue- and cell-type-specific components. Moreover, our data highlight the critical importance of genetic background in mouse aging studies, establish the Xpg-/- mouse as a valid model for the severe form of human XPG patients and segmental accelerated aging, and strengthen the link between DNA damage and aging.

  7. Cell-autonomous progeroid changes in conditional mouse models for repair endonuclease XPG deficiency.

    Directory of Open Access Journals (Sweden)

    Sander Barnhoorn

    2014-10-01

    Full Text Available As part of the Nucleotide Excision Repair (NER process, the endonuclease XPG is involved in repair of helix-distorting DNA lesions, but the protein has also been implicated in several other DNA repair systems, complicating genotype-phenotype relationship in XPG patients. Defects in XPG can cause either the cancer-prone condition xeroderma pigmentosum (XP alone, or XP combined with the severe neurodevelopmental disorder Cockayne Syndrome (CS, or the infantile lethal cerebro-oculo-facio-skeletal (COFS syndrome, characterized by dramatic growth failure, progressive neurodevelopmental abnormalities and greatly reduced life expectancy. Here, we present a novel (conditional Xpg-/- mouse model which -in a C57BL6/FVB F1 hybrid genetic background- displays many progeroid features, including cessation of growth, loss of subcutaneous fat, kyphosis, osteoporosis, retinal photoreceptor loss, liver aging, extensive neurodegeneration, and a short lifespan of 4-5 months. We show that deletion of XPG specifically in the liver reproduces the progeroid features in the liver, yet abolishes the effect on growth or lifespan. In addition, specific XPG deletion in neurons and glia of the forebrain creates a progressive neurodegenerative phenotype that shows many characteristics of human XPG deficiency. Our findings therefore exclude that both the liver as well as the neurological phenotype are a secondary consequence of derailment in other cell types, organs or tissues (e.g. vascular abnormalities and support a cell-autonomous origin caused by the DNA repair defect itself. In addition they allow the dissection of the complex aging process in tissue- and cell-type-specific components. Moreover, our data highlight the critical importance of genetic background in mouse aging studies, establish the Xpg-/- mouse as a valid model for the severe form of human XPG patients and segmental accelerated aging, and strengthen the link between DNA damage and aging.

  8. The mechanism of nucleotide excision repair-mediated UV-induced mutagenesis in nonproliferating cells.

    Science.gov (United States)

    Kozmin, Stanislav G; Jinks-Robertson, Sue

    2013-03-01

    Following the irradiation of nondividing yeast cells with ultraviolet (UV) light, most induced mutations are inherited by both daughter cells, indicating that complementary changes are introduced into both strands of duplex DNA prior to replication. Early analyses demonstrated that such two-strand mutations depend on functional nucleotide excision repair (NER), but the molecular mechanism of this unique type of mutagenesis has not been further explored. In the experiments reported here, an ade2 adeX colony-color system was used to examine the genetic control of UV-induced mutagenesis in nondividing cultures of Saccharomyces cerevisiae. We confirmed a strong suppression of two-strand mutagenesis in NER-deficient backgrounds and demonstrated that neither mismatch repair nor interstrand crosslink repair affects the production of these mutations. By contrast, proteins involved in the error-prone bypass of DNA damage (Rev3, Rev1, PCNA, Rad18, Pol32, and Rad5) and in the early steps of the DNA-damage checkpoint response (Rad17, Mec3, Ddc1, Mec1, and Rad9) were required for the production of two-strand mutations. There was no involvement, however, for the Pol η translesion synthesis DNA polymerase, the Mms2-Ubc13 postreplication repair complex, downstream DNA-damage checkpoint factors (Rad53, Chk1, and Dun1), or the Exo1 exonuclease. Our data support models in which UV-induced mutagenesis in nondividing cells occurs during the Pol ζ-dependent filling of lesion-containing, NER-generated gaps. The requirement for specific DNA-damage checkpoint proteins suggests roles in recruiting and/or activating factors required to fill such gaps.

  9. Nanoparticles carrying neurotrophin-3-modified Schwann cells promote repair of sciatic nerve defects

    Institute of Scientific and Technical Information of China (English)

    Haibin Zong; Hongxing Zhao; Yilei Zhao; Jingling Jia; Libin Yang; Chao Ma; Yang Zhang; Yuzhen Dong

    2013-01-01

    Schwann cells and neurotrophin-3 play an important role in neural regeneration, but the secretion of neurotrophin-3 from Schwann cells is limited, and exogenous neurotrophin-3 is inactived easily in vivo. In this study, we have transfected neurotrophin-3 into Schwann cells cultured in vitro using nanoparticle liposomes. Results showed that neurotrophin-3 was successfully transfected into Schwann cells, where it was expressed effectively and steadily. A composite of Schwann cells transfected with neurotrophin-3 and poly(lactic-co-glycolic acid) biodegradable conduits was transplanted into rats to repair 10-mm sciatic nerve defects. Transplantation of the composite scaffold could restore the myoelectricity and wave amplitude of the sciatic nerve by electrophysiological examination, promote nerve axonal and myelin regeneration, and delay apoptosis of spinal motor neurons. Experimental findings indicate that neurotrophin-3 transfected Schwann cells combined with bridge grafting can promote neural regeneration and functional recovery after nerve injury.

  10. Epithelial cell senescence impairs repair process and exacerbates inflammation after airway injury

    Directory of Open Access Journals (Sweden)

    Nagai Atsushi

    2011-06-01

    Full Text Available Abstract Background Genotoxic stress, such as by exposure to bromodeoxyuridine (BrdU and cigarette smoke, induces premature cell senescence. Recent evidence indicates that cellular senescence of various types of cells is accelerated in COPD patients. However, whether the senescence of airway epithelial cells contributes to the development of airway diseases is unknown. The present study was designed to test the hypothesis that premature senescence of airway epithelial cells (Clara cells impairs repair processes and exacerbates inflammation after airway injury. Methods C57/BL6J mice were injected with the Clara-cell-specific toxicant naphthalene (NA on days 0, 7, and 14, and each NA injection was followed by a daily dose of BrdU on each of the following 3 days, during which regenerating cells were allowed to incorporate BrdU into their DNA and to senesce. The p38 MAPK inhibitor SB202190 was injected 30 minutes before each BrdU dose. Mice were sacrificed at different times until day 28 and lungs of mice were obtained to investigate whether Clara cell senescence impairs airway epithelial regeneration and exacerbates airway inflammation. NCI-H441 cells were induced to senesce by exposure to BrdU or the telomerase inhibitor MST-312. Human lung tissue samples were obtained from COPD patients, asymptomatic smokers, and nonsmokers to investigate whether Clara cell senescence is accelerated in the airways of COPD patients, and if so, whether it is accompanied by p38 MAPK activation. Results BrdU did not alter the intensity of the airway epithelial injury or inflammation after a single NA exposure. However, after repeated NA exposure, BrdU induced epithelial cell (Clara cell senescence, as demonstrated by a DNA damage response, p21 overexpression, increased senescence-associated β-galactosidase activity, and growth arrest, which resulted in impaired epithelial regeneration. The epithelial senescence was accompanied by p38 MAPK-dependent airway

  11. DNA Repair by Homologous Recombination, But Not by Nonhomologous End Joining, Is Elevated in Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Zhiyong Mao

    2009-07-01

    Full Text Available Aberrant double-stranded break (DSB repair leads to genomic instability, which is a hallmark of malignant cells. Double-stranded breaks are repaired by two pathways: homologous recombination (HR and nonhomologous DNA end joining (NHEJ. It is not known whether these repair pathways are affected in sporadic breast tumors. Here, we examined the efficiency of HR and NHEJ repair in a panel of sporadic breast cancer cell lines and tested whether the efficiency of HR or NHEJ correlates with radioresistance. Homologous recombination and NHEJ in breast cancer cells were analyzed using in vivo fluorescent assays. Unexpectedly, our analysis revealed that the efficiency of HR is significantly elevated in breast cancer cells compared with normal mammary epithelial cells. In contrast, the efficiency of NHEJ in breast cancer cells is not different from normal cells. Overall, breast cancer cells were more sensitive to radiation than normal cells, but the levels of resistance did not correlate with either HR or NHEJ efficiency. Thus, we demonstrate that sporadic breast cancers are not associated with a deficiency in DSB repair, but rather with upregulation of the HR pathway. Our finding of elevated HR in sporadic breast cancer cell lines suggests that therapies directed against the components of HR will be highly tumor-specific.

  12. DNA Repair by Homologous Recombination, But Not by Nonhomologous End Joining, Is Elevated in Breast Cancer Cells12

    Science.gov (United States)

    Mao, Zhiyong; Jiang, Ying; Liu, Xiang; Seluanov, Andrei; Gorbunova, Vera

    2009-01-01

    Aberrant double-stranded break (DSB) repair leads to genomic instability, which is a hallmark of malignant cells. Double-stranded breaks are repaired by two pathways: homologous recombination (HR) and nonhomologous DNA end joining (NHEJ). It is not known whether these repair pathways are affected in sporadic breast tumors. Here, we examined the efficiency of HR and NHEJ repair in a panel of sporadic breast cancer cell lines and tested whether the efficiency of HR or NHEJ correlates with radioresistance. Homologous recombination and NHEJ in breast cancer cells were analyzed using in vivo fluorescent assays. Unexpectedly, our analysis revealed that the efficiency of HR is significantly elevated in breast cancer cells compared with normal mammary epithelial cells. In contrast, the efficiency of NHEJ in breast cancer cells is not different from normal cells. Overall, breast cancer cells were more sensitive to radiation than normal cells, but the levels of resistance did not correlate with either HR or NHEJ efficiency. Thus, we demonstrate that sporadic breast cancers are not associated with a deficiency in DSB repair, but rather with upregulation of the HR pathway. Our finding of elevated HR in sporadic breast cancer cell lines suggests that therapies directed against the components of HR will be highly tumor-specific. PMID:19568413

  13. Activation of the aryl hydrocarbon receptor reduces the number of precursor and effector T cells, but preserves thymic CD4(+)CD25(+)Foxp3(+) regulatory T cells

    NARCIS (Netherlands)

    Schulz, V.J.; Smit, J.J.; Bol-Schoenmakers, M.; van Duursen, M.B.M.; van den Berg, M.; Pieters, R.H.H.

    2012-01-01

    Aryl hydrocarbon receptor (AhR) activation suppresses immune responses, including allergic sensitization, by increasing the percentage of regulatory (Treg) cells. Furthermore, AhR activation is known to affect thymic precursor T cells. However, the effect of AhR activation on intrathymic CD4(+)CD25(

  14. Adult stem cells in neural repair: Current options, limitations and perspectives.

    Science.gov (United States)

    Mariano, Eric Domingos; Teixeira, Manoel Jacobsen; Marie, Suely Kazue Nagahashi; Lepski, Guilherme

    2015-03-26

    Stem cells represent a promising step for the future of regenerative medicine. As they are able to differentiate into any cell type, tissue or organ, these cells are great candidates for treatments against the worst diseases that defy doctors and researchers around the world. Stem cells can be divided into three main groups: (1) embryonic stem cells; (2) fetal stem cells; and (3) adult stem cells. In terms of their capacity for proliferation, stem cells are also classified as totipotent, pluripotent or multipotent. Adult stem cells, also known as somatic cells, are found in various regions of the adult organism, such as bone marrow, skin, eyes, viscera and brain. They can differentiate into unipotent cells of the residing tissue, generally for the purpose of repair. These cells represent an excellent choice in regenerative medicine, every patient can be a donor of adult stem cells to provide a more customized and efficient therapy against various diseases, in other words, they allow the opportunity of autologous transplantation. But in order to start clinical trials and achieve great results, we need to understand how these cells interact with the host tissue, how they can manipulate or be manipulated by the microenvironment where they will be transplanted and for how long they can maintain their multipotent state to provide a full regeneration.

  15. Identification of novel radiosensitizers in a high-throughput, cell-based screen for DSB repair inhibitors.

    Science.gov (United States)

    Goglia, Alexander G; Delsite, Robert; Luz, Antonio N; Shahbazian, David; Salem, Ahmed F; Sundaram, Ranjini K; Chiaravalli, Jeanne; Hendrikx, Petrus J; Wilshire, Jennifer A; Jasin, Maria; Kluger, Harriet M; Glickman, J Fraser; Powell, Simon N; Bindra, Ranjit S

    2015-02-01

    Most cancer therapies involve a component of treatment that inflicts DNA damage in tumor cells, such as double-strand breaks (DSBs), which are considered the most serious threat to genomic integrity. Complex systems have evolved to repair these lesions, and successful DSB repair is essential for tumor cell survival after exposure to ionizing radiation (IR) and other DNA-damaging agents. As such, inhibition of DNA repair is a potentially efficacious strategy for chemo- and radiosensitization. Homologous recombination (HR) and nonhomologous end-joining (NHEJ) represent the two major pathways by which DSBs are repaired in mammalian cells. Here, we report the design and execution of a high-throughput, cell-based small molecule screen for novel DSB repair inhibitors. We miniaturized our recently developed dual NHEJ and HR reporter system into a 384-well plate-based format and interrogated a diverse library of 20,000 compounds for molecules that selectively modulate NHEJ and HR repair in tumor cells. We identified a collection of novel hits that potently inhibit DSB repair, and we have validated their functional activity in a comprehensive panel of orthogonal secondary assays. A selection of these inhibitors was found to radiosensitize cancer cell lines in vitro, which suggests that they may be useful as novel chemo- and radio sensitizers. Surprisingly, we identified several FDA-approved drugs, including the calcium channel blocker mibefradil dihydrochloride, that demonstrated activity as DSB repair inhibitors and radiosensitizers. These findings suggest the possibility for repurposing them as tumor cell radiosensitizers in the future. Accordingly, we recently initiated a phase I clinical trial testing mibefradil as a glioma radiosensitizer.

  16. Defects in Base Excision Repair Sensitize Cells to Manganese in S. cerevisiae

    Directory of Open Access Journals (Sweden)

    Adrienne P. Stephenson

    2013-01-01

    Full Text Available Manganese (Mn is essential for normal physiologic functioning; therefore, deficiencies and excess intake of manganese can result in disease. In humans, prolonged exposure to manganese causes neurotoxicity characterized by Parkinson-like symptoms. Mn2+ has been shown to mediate DNA damage possibly through the generation of reactive oxygen species. In a recent publication, we showed that Mn induced oxidative DNA damage and caused lesions in thymines. This study further investigates the mechanisms by which cells process Mn2+-mediated DNA damage using the yeast S. cerevisiae. The strains most sensitive to Mn2+ were those defective in base excision repair, glutathione synthesis, and superoxide dismutase mutants. Mn2+ caused a dose-dependent increase in the accumulation of mutations using the CAN1 and lys2-10A mutator assays. The spectrum of CAN1 mutants indicates that exposure to Mn results in accumulation of base substitutions and frameshift mutations. The sensitivity of cells to Mn2+ as well as its mutagenic effect was reduced by N-acetylcysteine, glutathione, and Mg2+. These data suggest that Mn2+ causes oxidative DNA damage that requires base excision repair for processing and that Mn interferes with polymerase fidelity. The status of base excision repair may provide a biomarker for the sensitivity of individuals to manganese.

  17. Identification of Drugs that Regulate Dermal Stem Cells and Enhance Skin Repair

    Science.gov (United States)

    Naska, Sibel; Yuzwa, Scott A.; Johnston, Adam P.W.; Paul, Smitha; Smith, Kristen M.; Paris, Maryline; Sefton, Michael V.; Datti, Alessandro; Miller, Freda D.; Kaplan, David R.

    2015-01-01

    Summary Here, we asked whether we could identify pharmacological agents that enhance endogenous stem cell function to promote skin repair, focusing on skin-derived precursors (SKPs), a dermal precursor cell population. Libraries of compounds already used in humans were screened for their ability to enhance the self-renewal of human and rodent SKPs. We identified and validated five such compounds, and showed that two of them, alprostadil and trimebutine maleate, enhanced the repair of full thickness skin wounds in middle-aged mice. Moreover, SKPs isolated from drug-treated skin displayed long-term increases in self-renewal when cultured in basal growth medium without drugs. Both alprostadil and trimebutine maleate likely mediated increases in SKP self-renewal by moderate hyperactivation of the MEK-ERK pathway. These findings identify candidates for potential clinical use in human skin repair, and provide support for the idea that pharmacological activation of endogenous tissue precursors represents a viable therapeutic strategy. PMID:26724904

  18. Identification of Drugs that Regulate Dermal Stem Cells and Enhance Skin Repair

    Directory of Open Access Journals (Sweden)

    Sibel Naska

    2016-01-01

    Full Text Available Here, we asked whether we could identify pharmacological agents that enhance endogenous stem cell function to promote skin repair, focusing on skin-derived precursors (SKPs, a dermal precursor cell population. Libraries of compounds already used in humans were screened for their ability to enhance the self-renewal of human and rodent SKPs. We identified and validated five such compounds, and showed that two of them, alprostadil and trimebutine maleate, enhanced the repair of full thickness skin wounds in middle-aged mice. Moreover, SKPs isolated from drug-treated skin displayed long-term increases in self-renewal when cultured in basal growth medium without drugs. Both alprostadil and trimebutine maleate likely mediated increases in SKP self-renewal by moderate hyperactivation of the MEK-ERK pathway. These findings identify candidates for potential clinical use in human skin repair, and provide support for the idea that pharmacological activation of endogenous tissue precursors represents a viable therapeutic strategy.

  19. DNA repair. [UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Setlow, R.

    1978-01-01

    Some topics discussed are as follows: difficulty in extrapolating data from E. coli to mammalian systems; mutations caused by UV-induced changes in DNA; mutants deficient in excision repair; other postreplication mechanisms; kinds of excision repair systems; detection of repair by biochemical or biophysical means; human mutants deficient in repair; mutagenic effects of UV on XP cells; and detection of UV-repair defects among XP individuals. (HLW)

  20. Head and neck squamous-cell cancer and its association with polymorphic enzymes of xenobiotic metabolism and repair.

    Science.gov (United States)

    Harth, Volker; Schafer, Martin; Abel, Josef; Maintz, Laura; Neuhaus, Thomas; Besuden, Mette; Primke, Robert; Wilkesmann, Anja; Thier, Ricarda; Vetter, Hans; Ko, Yon-Dschun; Bruning, Thomas; Bolt, Hermann M; Ickstadt, Katja

    2008-01-01

    Tobacco smoking, alcohol drinking, and occupational exposures to polycyclic aromatic hydrocarbons are the major proven risk factors for human head and neck squamous-cell cancer (HNSCC). Major research focus on gene-environment interactions concerning HNSCC has been on genes encoding enzymes of metabolism for tobacco smoke constituents and repair enzymes. To investigate the role of genetically determined individual predispositions in enzymes of xenobiotic metabolism and in repair enzymes under the exogenous risk factor tobacco smoke in the carcinogenesis of HNSCC, we conducted a case-control study on 312 cases and 300 noncancer controls. We focused on the impact of 22 sequence variations in CYP1A1, CYP1B1, CYP2E1, ERCC2/XPD, GSTM1, GSTP1, GSTT1, NAT2, NQO1, and XRCC1. To assess relevant main and interactive effects of polymorphic genes on the susceptibility to HNSCC we used statistical models such as logic regression and a Bayesian version of logic regression. In subgroup analysis of nonsmokers, main effects in ERCC2 (Lys751Gln) C/C genotype and combined ERCC2 (Arg156Arg) C/A and A/A genotypes were predominant. When stratifying for smokers, the data revealed main effects on combined CYP1B1 (Leu432Val) C/G and G/G genotypes, followed by CYP1B1 (Leu432Val) G/G genotype and CYP2E1 (-70G>T) G/T genotype. When fitting logistic regression models including relevant main effects and interactions in smokers, we found relevant associations of CYP1B1 (Leu432Val) C/G genotype and CYP2E1 (-70G>T) G/T genotype (OR, 10.84; 95% CI, 1.64-71.53) as well as CYP1B1 (Leu432Val) G/G genotype and GSTM1 null/null genotype (OR, 11.79; 95% CI, 2.18-63.77) with HNSCC. The findings underline the relevance of genotypes of polymorphic CYP1B1 combined with exposures to tobacco smoke.

  1. Track-event theory of cell survival with second-order repair.

    Science.gov (United States)

    Besserer, Jürgen; Schneider, Uwe

    2015-05-01

    When fractionation schemes for hypofractionation and stereotactic body radiotherapy are considered, a reliable cell survival model at high dose is needed for calculating doses of similar biological effectiveness. In this work, a simple model for cell survival which is valid also at high dose is developed from Poisson statistics. It is assumed that a cell is killed by an event that is defined by two double-strand breaks on the same or different chromosomes. Two different mechanisms can produce events. A one-track event is always represented by two simultaneous double-strand breaks. A two-track event results in one double-strand break. Therefore, at least two two-track events on the same or different chromosomes are necessary to produce an event. It is assumed that two double-strand breaks can be repaired with a certain repair probability. Both the one-track events and the two-track events are statistically independent. From the stochastic nature of cell killing which is described by the Poisson distribution, the cell survival probability was derived. The model was fitted to experimental data. It was shown that a solution based on Poisson statistics exists for cell survival. It exhibits exponential cell survival at high dose and a finite gradient of cell survival at vanishing dose, which is in agreement with experimental cell studies. The model fits the experimental data as well as the LQ model and is based on two free parameters. It was shown that cell survival can be described with a simple analytical formula on the basis of Poisson statistics. This solution represents in the limit of large dose the typical exponential behavior and predicts cell survival as well as the LQ model.

  2. Increasing Melanoma—Too Many Skin Cell Damages or Too Few Repairs?

    Directory of Open Access Journals (Sweden)

    Örjan Hallberg

    2013-02-01

    Full Text Available Skin melanoma rates have been increasing for a long time in many Western countries. The object of this study was to apply modern problem-solving theory normally used to clear industrial problems to search for roots and causes of this medical question. Increasing cancer rates can be due to too many cell damage incidents or to too few repairs. So far, it has been assumed that the melanoma epidemic mainly is caused by increasing sun tanning habits. In order to explore this problem in more detail, we used cancer statistics from several countries over time and space. Detailed analysis of data obtained and a model study to evaluate the effects from increased damages or decreased repairs clearly indicate that the main reason behind the melanoma problem is a disturbed immune system. The possibility to introduce efficient corrective actions is apparent.

  3. Whole ovary immunohistochemistry for monitoring cell proliferation and ovulatory wound repair in the mouse

    Directory of Open Access Journals (Sweden)

    Singavarapu Rajasekhar

    2010-08-01

    Full Text Available Abstract Background Ovarian surface epithelial cells are thought to be a precursor cell type for ovarian carcinoma. It has been proposed that an increased rate of ovarian surface epithelial cell proliferation during ovulatory wound repair contributes to the accumulation of genetic changes and cell transformation. The proliferation of ovarian surface epithelial cells during ovulatory wound repair has been studied primarily using immunohistochemical staining of paraffin-embedded ovary sections. However, such analyses require complex reconstruction from serially-cut ovary sections for the visualization and quantification of the cells on the ovarian surface. In order to directly visualize the proliferation and organization of the ovarian surface epithelial cells, we developed a technique for immunohistochemical staining of whole mouse ovaries. Using this method, we analyzed cell proliferation and morphologic changes in mouse ovarian surface epithelial cells during follicle growth and ovulatory wound repair. Methods Three-week old FVB/N female mice were superovulated by sequential administration of pregnant mare's serum gonadotropin (PMSG and human chorionic gonadotropin (hCG. Ten hours after hCG administration, mice were given 5-bromo-2-deoxyuridine (BrdU and euthanized two hours after BrdU administration for ovary isolation. The levels of incorporated BrdU in the ovarian surface epithelial cells were measured by staining paraffin-embedded ovary sections and whole ovaries with the BrdU antibody. Re-epithelialization of the ovarian surface after ovulatory rupture was visualized by immunohistochemical staining with E-cadherin and Keratin 8 in paraffin-embedded ovary sections and whole ovaries. Results We determined that active proliferation of ovarian epithelial surface cells primarily occurs during antral follicle formation and, to a lesser extent, in response to an ovulatory wound. We also demonstrated that ovarian surface epithelial cells exhibit a

  4. Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair

    DEFF Research Database (Denmark)

    Akbari, Mansour; Keijzers, Guido; Maynard, Scott

    2014-01-01

    slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I...... by rotenone. Our results suggest that the amount of DNA ligase III in mitochondria may be critical for cell survival following prolonged oxidative stress, and demonstrate a functional link between mitochondrial DNA damage and repair, cell survival upon oxidative stress, and removal of dysfunctional......Base excision repair (BER) is the most prominent DNA repair pathway in human mitochondria. BER also results in a temporary generation of AP-sites, single-strand breaks and nucleotide gaps. Thus, incomplete BER can result in the generation of DNA repair intermediates that can disrupt mitochondrial...

  5. The role of stem cells in airway repair: implications for the origins of lung cancer

    Institute of Scientific and Technical Information of China (English)

    Michael S.Mulvihill; Johannes R.Kratz; Patrick Pham; David M.Jablons; Biao He

    2013-01-01

    Lung cancer is the leading cause of cancer-related deaths worldwide.Recently,advancements in our ability to identify and study stem cell populations in the lung have helped researchers to elucidate the central role that cells with stem cell-like properties may have in lung tumorigenesis.Much of this research has focused on the use of the airway repair model to study response to injury.In this review,we discuss the primary evidence of the role that cancer stem cells play in lung cancer development.The implications of a stem cell origin of lung cancer are reviewed,and the importance of ongoing research to identify novel therapeutic and prognostic targets is reiterated.

  6. Endogenous ligands of the aryl hydrocarbon receptor regulate lung dendritic cell function.

    Science.gov (United States)

    Thatcher, Thomas H; Williams, Marc A; Pollock, Stephen J; McCarthy, Claire E; Lacy, Shannon H; Phipps, Richard P; Sime, Patricia J

    2016-01-01

    The aryl hydrocarbon receptor (AhR) is a transcription factor that has been extensively studied as a regulator of toxicant metabolism. However, recent evidence indicates that the AhR also plays an important role in immunity. We hypothesized that the AhR is a novel, immune regulator of T helper type 2 (Th2) -mediated allergic airway disease. Here, we report that AhR-deficient mice develop increased allergic responses to the model allergen ovalbumin (OVA), which are driven in part by increased dendritic cell (DC) functional activation. AhR knockout (AhR(-/-) ) mice sensitized and challenged with OVA develop an increased inflammatory response in the lung compared with wild-type controls, with greater numbers of inflammatory eosinophils and neutrophils, greater T-cell proliferation, greater production of Th2 cytokines, and higher levels of OVA-specific IgE and IgG1. Lung DCs from AhR(-/-) mice stimulated antigen-specific proliferation and Th2 cytokine production by naive T cells in vitro. Additionally, AhR(-/-) DCs produced higher levels of tumour necrosis factor-α and interleukin-6, which promote Th2 differentiation, and expressed higher cell surface levels of stimulatory MHC Class II and CD86 molecules. Overall, loss of the AhR was associated with enhanced T-cell activation by pulmonary DCs and heightened pro-inflammatory allergic responses. This suggests that endogenous AhR ligands are involved in the normal regulation of Th2-mediated immunity in the lung via a DC-dependent mechanism. Therefore, the AhR may represent an important target for therapeutic intervention in allergic airways inflammation.

  7. Dietary phytochemicals, HDAC inhibition, and DNA damage/repair defects in cancer cells

    Directory of Open Access Journals (Sweden)

    Rajendran Praveen

    2011-10-01

    Full Text Available Abstract Genomic instability is a common feature of cancer etiology. This provides an avenue for therapeutic intervention, since cancer cells are more susceptible than normal cells to DNA damaging agents. However, there is growing evidence that the epigenetic mechanisms that impact DNA methylation and histone status also contribute to genomic instability. The DNA damage response, for example, is modulated by the acetylation status of histone and non-histone proteins, and by the opposing activities of histone acetyltransferase and histone deacetylase (HDAC enzymes. Many HDACs overexpressed in cancer cells have been implicated in protecting such cells from genotoxic insults. Thus, HDAC inhibitors, in addition to unsilencing tumor suppressor genes, also can silence DNA repair pathways, inactivate non-histone proteins that are required for DNA stability, and induce reactive oxygen species and DNA double-strand breaks. This review summarizes how dietary phytochemicals that affect the epigenome also can trigger DNA damage and repair mechanisms. Where such data is available, examples are cited from studies in vitro and in vivo of polyphenols, organosulfur/organoselenium compounds, indoles, sesquiterpene lactones, and miscellaneous agents such as anacardic acid. Finally, by virtue of their genetic and epigenetic mechanisms, cancer chemopreventive agents are being redefined as chemo- or radio-sensitizers. A sustained DNA damage response coupled with insufficient repair may be a pivotal mechanism for apoptosis induction in cancer cells exposed to dietary phytochemicals. Future research, including appropriate clinical investigation, should clarify these emerging concepts in the context of both genetic and epigenetic mechanisms dysregulated in cancer, and the pros and cons of specific dietary intervention strategies.

  8. A modified fluorimetric host cell reactivation assay to determine the repair capacity of primary keratinocytes, melanocytes and fibroblasts

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    Gebhard Daniel

    2010-06-01

    Full Text Available Abstract Background The Host Cell Reactivation Assay (HCRA is widely used to identify circumstances and substances affecting the repair capacity of cells, however, it is restricted by the transfection procedure used and the sensitivity of the detection method. Primary skin cells are particularly difficult to transfect, and therefore sensitive methods are needed to detect any variations due to the cell-type or inter-individual differences or changes induced by diverse substances. A sensitive and repeatable method to detect the repair capacity of skin cells would be useful in two different aspects: On the one hand, to identify substances influencing the repair capacity in a positive manner (these substances could be promising ingredients for cosmetic products and on the other hand, to exclude the negative effects of substances on the repair capacity (this could serve as one step further towards replacing or at least reducing animal testing. Results In this paper, we present a rapid and sensitive assay to determine the repair capacity of primary keratinocytes, melanocytes and fibroblasts based on two wave-length Green Fluorescent Protein (GFP and DsRed reporter technology in order to test different substances and their potential to influence the DNA repair capacity. For the detection of plasmid restoration, we used FACS technology, which, in comparison to luminometer technology, is highly sensitive and allows single cell based analysis. The usefulness of this assay and studying the repair capacity is demonstrated by the evidence that DNA repair is repressed by Cyclosporin A in fibroblasts. Conclusions The methodology described in this paper determines the DNA repair capacity in different types of human skin cells. The described transfection protocol is suitable for the transfection of melanocytes, keratinocytes and fibroblasts, reaching efficacies suitable for the detection of the restored plasmids by FACS technology. Therefore the repair capacity

  9. Development of an assay to measure mutagenic non-homologous end-joining repair activity in mammalian cells.

    Science.gov (United States)

    Bindra, Ranjit S; Goglia, Alexander G; Jasin, Maria; Powell, Simon N

    2013-06-01

    Double-strand break (DSB) repair pathways are critical for the maintenance of genomic integrity and the prevention of tumorigenesis in mammalian cells. Here, we present the development and validation of a novel assay to measure mutagenic non-homologous end-joining (NHEJ) repair in living cells, which is inversely related to canonical NHEJ and is based on the sequence-altering repair of a single site-specific DSB at an intrachromosomal locus. We have combined this mutagenic NHEJ assay with an established homologous recombination (HR) assay such that both pathways can be monitored simultaneously. In addition, we report the development of a ligand-responsive I-SceI protein, in which the timing and kinetics of DSB induction can be precisely controlled by regulating protein stability and cellular localization in cells. Using this system, we report that mutagenic NHEJ repair is suppressed in growth-arrested and serum-deprived cells, suggesting that end-joining activity in proliferating cells is more likely to be mutagenic. Collectively, the novel DSB repair assay and inducible I-SceI will be useful tools to further elucidate the complexities of NHEJ and HR repair.

  10. DNA repair efficiency in germ cells and early mouse embryos and consequences for radiation-induced transgenerational genomic damage

    Energy Technology Data Exchange (ETDEWEB)

    Marchetti, Francesco; Wyrobek, Andrew J.

    2009-01-18

    Exposure to ionizing radiation and other environmental agents can affect the genomic integrity of germ cells and induce adverse health effects in the progeny. Efficient DNA repair during gametogenesis and the early embryonic cycles after fertilization is critical for preventing transmission of DNA damage to the progeny and relies on maternal factors stored in the egg before fertilization. The ability of the maternal repair machinery to repair DNA damage in both parental genomes in the fertilizing egg is especially crucial for the fertilizing male genome that has not experienced a DNA repair-competent cellular environment for several weeks prior to fertilization. During the DNA repair-deficient period of spermatogenesis, DNA lesions may accumulate in sperm and be carried into the egg where, if not properly repaired, could result in the formation of heritable chromosomal aberrations or mutations and associated birth defects. Studies with female mice deficient in specific DNA repair genes have shown that: (i) cell cycle checkpoints are activated in the fertilized egg by DNA damage carried by the sperm; and (ii) the maternal genotype plays a major role in determining the efficiency of repairing genomic lesions in the fertilizing sperm and directly affect the risk for abnormal reproductive outcomes. There is also growing evidence that implicates DNA damage carried by the fertilizing gamete as a mediator of postfertilization processes that contribute to genomic instability in subsequent generations. Transgenerational genomic instability most likely involves epigenetic mechanisms or error-prone DNA repair processes in the early embryo. Maternal and embryonic DNA repair processes during the early phases of mammalian embryonic development can have far reaching consequences for the genomic integrity and health of subsequent generations.

  11. In vivo importance of homologous recombination DNA repair for mouse neural stem and progenitor cells.

    Directory of Open Access Journals (Sweden)

    Laure Rousseau

    Full Text Available We characterized the in vivo importance of the homologous recombination factor RAD54 for the developing mouse brain cortex in normal conditions or after ionizing radiation exposure. Contrary to numerous homologous recombination genes, Rad54 disruption did not impact the cortical development without exogenous stress, but it dramatically enhanced the radiation sensitivity of neural stem and progenitor cells. This resulted in the death of all cells irradiated during S or G2, whereas the viability of cells irradiated in G1 or G0 was not affected by Rad54 disruption. Apoptosis occurred after long arrests at intra-S and G2/M checkpoints. This concerned every type of neural stem and progenitor cells, showing that the importance of Rad54 for radiation response was linked to the cell cycle phase at the time of irradiation and not to the differentiation state. In the developing brain, RAD54-dependent homologous recombination appeared absolutely required for the repair of damages induced by ionizing radiation during S and G2 phases, but not for the repair of endogenous damages in normal conditions. Altogether our data support the existence of RAD54-dependent and -independent homologous recombination pathways.

  12. Topical Delivery of Mesenchymal Stem Cells “Secretomes” in Wound Repair

    Directory of Open Access Journals (Sweden)

    Indah Julianto

    2016-11-01

    Full Text Available Wound healing requires a coordinated interplay among cells, growth factors, and extracellular matrix proteins. Central to this process is the endogenous mesenchymal stem cell (MSC, which coordinates the repair response by recruiting other host cells and secreting growth factors and matrix proteins. MSCs are self-renewing multipotent stem cells that can differentiate into various lineages of mesenchymal origin such as bone, cartilage, tendon, and fat. In addition to multilineage differentiation capacity, MSCs regulate immune response and inflammation and possess powerful tissue protective and reparative mechanisms, making these cells attractive for treatment of different diseases. The beneficial effect of exogenous MSCs on wound healing was observed in a variety of animal models and in reported clinical cases. Specifically, they have been successfully used to treat chronic wounds and stimulate stalled healing processes. Recent studies revealed that human placental membranes are a rich source of MSCs for tissue regeneration and repair. This review provides a concise summary of current knowledge of biological properties of MSCs and describes the use of MSCs for wound healing. In particular, the scope of this review focuses on the role MSCs have in each phase of the wound-healing process, and clinical reports transplatation MSCs – secretomes in chronical ulcer.

  13. Methotrexate induces DNA damage and inhibits homologous recombination repair in choriocarcinoma cells

    Directory of Open Access Journals (Sweden)

    Xie L

    2016-11-01

    Full Text Available Lisha Xie,1,* Tiancen Zhao,1,2,* Jing Cai,1 You Su,1 Zehua Wang,1 Weihong Dong1 1Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 2Department of Obstetrics and Gynecology, Central Hospital of Wuhan, Wuhan, China *These authors contributed equally to this work Objective: The objective of this study was to investigate the mechanism of sensitivity to methotrexate (MTX in human choriocarcinoma cells regarding DNA damage response. Methods: Two choriocarcinoma cancer cell lines, JAR and JEG-3, were utilized in this study. An MTX-sensitive osteosarcoma cell line MG63, an MTX-resistant epithelial ovarian cancer cell line A2780 and an MTX-resistant cervical adenocarcinoma cell line Hela served as controls. Cell viability assay was carried out to assess MTX sensitivity of cell lines. MTX-induced DNA damage was evaluated by comet assay. Quantitative reverse transcription polymerase chain reaction was used to detect the mRNA levels of BRCA1, BRCA2, RAD51 and RAD52. The protein levels of γH2AX, RAD 51 and p53 were analyzed by Western blot. Results: Remarkable DNA strand breaks were observed in MTX-sensitive cell lines (JAR, JEG-3 and MG63 but not in MTX-resistant cancer cells (A2780 and Hela after 48 h of MTX treatment. Only in the choriocarcinoma cells, the expression of homologous recombination (HR repair gene RAD51 was dramatically suppressed by MTX in a dose- and time-dependent manner, accompanied with the increase in p53. Conclusion: The MTX-induced DNA strand breaks accompanied by deficiencies in HR repair may contribute to the hypersensitivity to chemotherapy in choriocarcinoma. Keywords: choriocarcinoma, chemotherapy hypersensitivity, DNA double-strand break, RAD51, p53

  14. Rotator cuff repair using cell sheets derived from human rotator cuff in a rat model.

    Science.gov (United States)

    Harada, Yoshifumi; Mifune, Yutaka; Inui, Atsuyuki; Sakata, Ryosuke; Muto, Tomoyuki; Takase, Fumiaki; Ueda, Yasuhiro; Kataoka, Takeshi; Kokubu, Takeshi; Kuroda, Ryosuke; Kurosaka, Masahiro

    2017-02-01

    To achieve biological regeneration of tendon-bone junctions, cell sheets of human rotator-cuff derived cells were used in a rat rotator cuff injury model. Human rotator-cuff derived cells were isolated, and cell sheets were made using temperature-responsive culture plates. Infraspinatus tendons in immunodeficient rats were resected bilaterally at the enthesis. In right shoulders, infraspinatus tendons were repaired by the transosseous method and covered with the cell sheet (sheet group), whereas the left infraspinatus tendons were repaired in the same way without the cell sheet (control group). Histological examinations (safranin-O and fast green staining, isolectin B4, type II collagen, and human-specific CD31) and mRNA expression (vascular endothelial growth factor; VEGF, type II collagen; Col2, and tenomodulin; TeM) were analyzed 4 weeks after surgery. Biomechanical tests were performed at 8 weeks. In the sheet group, proteoglycan at the enthesis with more type II collagen and isolectin B4 positive cells were seen compared with in the control group. Human specific CD31-positive cells were detected only in the sheet group. VEGF and Col2 gene expressions were higher and TeM gene expression was lower in the sheet group than in the control group. In mechanical testing, the sheet group showed a significantly higher ultimate failure load than the control group at 8 weeks. Our results indicated that the rotator-cuff derived cell sheet could promote cartilage regeneration and angiogenesis at the enthesis, with superior mechanical strength compared with the control. Treatment for rotator cuff injury using cell sheets could be a promising strategy for enthesis of tendon tissue engineering. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:289-296, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  15. Muscle repair and regeneration: stem cells, scaffolds, and the contributions of skeletal muscle to amphibian limb regeneration.

    Science.gov (United States)

    Milner, Derek J; Cameron, Jo Ann

    2013-01-01

    Skeletal muscle possesses a robust innate capability for repair of tissue damage. Natural repair of muscle damage is a stepwise process that requires the coordinated activity of a number of cell types, including infiltrating macrophages, resident myogenic and non-myogenic stem cells, and connective tissue fibroblasts. Despite the proficiency of this intrinsic repair capability, severe injuries that result in significant loss of muscle tissue overwhelm the innate repair process and require intervention if muscle function is to be restored. Recent advances in stem cell biology, regenerative medicine, and materials science have led to attempts at developing tissue engineering-based methods for repairing severe muscle defects. Muscle tissue also plays a role in the ability of tailed amphibians to regenerate amputated limbs through epimorphic regeneration. Muscle contributes adult stem cells to the amphibian regeneration blastema, but it can also contribute blastemal cells through the dedifferentiation of multinucleate myofibers into mononuclear precursors. This fascinating plasticity and its contributions to limb regeneration have prompted researchers to investigate the potential for mammalian muscle to undergo dedifferentiation. Several works have shown that mammalian myotubes can be fragmented into mononuclear cells and induced to re-enter the cell cycle, but mature myofibers are resistant to fragmentation. However, recent works suggest that there may be a path to inducing fragmentation of mature myofibers into proliferative multipotent cells with the potential for use in muscle tissue engineering and regenerative therapies.

  16. Combustion products of 1,3-butadiene inhibit catalase activity and induce expression of oxidative DNA damage repair enzymes in human bronchial epithelial cells.

    Science.gov (United States)

    Kennedy, Christopher H; Catallo, W James; Wilson, Vincent L; Mitchell, James B

    2009-10-01

    1,3-Butadiene, an important petrochemical, is commonly burned off when excess amounts need to be destroyed. This combustion process produces butadiene soot (BDS), which is composed of a complex mixture of polycyclic aromatic hydrocarbons in particulates ranging in size from DNA damage in NHBE cells. Thus, our aims were to determine the effect of butadiene soot ethanol extract (BSEE) on both enzyme activity and the expression of proteins involved in the repair of oxidative DNA damage. Catalase was found to be sensitive to BDS as catalase activity was potently diminished in the presence of BSEE. Using Western analysis, both the alpha isoform of human 8-oxoguanine DNA glycosylase (alpha-hOGG1) and human apurinic/apyrimidinic endonuclease (APE-1) were shown to be significantly overexpressed as compared to untreated controls after exposure of NHBE cells to BSEE. Our results indicate that BSEE is capable of effectively inactivating the antioxidant enzyme catalase, presumably via oxidation of protein amino acids. The presence of oxidized biomolecules may partially explain the extranuclear fluorescence that is detected when NHBE cells are treated with an organic extract of BDS. Overexpression of both alpha-hOGG1 and APE-1 proteins following treatment of NHBE cells with BSEE suggests that this mixture causes oxidative DNA damage.

  17. Aryl hydrocarbon receptor downregulates MYCN expression and promotes cell differentiation of neuroblastoma.

    Directory of Open Access Journals (Sweden)

    Pei-Yi Wu

    Full Text Available Neuroblastoma (NB is the most common malignant disease of infancy. MYCN amplification is a prognostic factor for NB and is a sign of highly malignant disease and poor patient prognosis. In this study, we aimed to investigate novel MYCN-related genes and assess how they affect NB cell behavior. The different gene expression found in 10 MYCN amplification NB tumors and 10 tumors with normal MYCN copy number were analyzed using tissue oligonucleotide microarrays. Ingenuity Pathway Analysis was subsequently performed to identify the potential genes involved in MYCN regulation pathways. Aryl hydrocarbon receptor (AHR, a receptor for dioxin-like compounds, was found to be inversely correlated with MYCN expression in NB tissues. This correlation was confirmed in a further 14 human NB samples. Moreover, AHR expression in NB tumors was found to correlate highly with histological grade of differentiation. In vitro studies revealed that AHR overexpression in NB cells induced spontaneous cell differentiation. In addition, it was found that ectopic expression of AHR suppressed MYCN promoter activity resulting in downregulation of MYCN expression. The suppression effect of AHR on the transcription of MYCN was compensated for by E2F1 overexpression, indicating that E2F1 is involved in the AHR-regulating MYCN pathway. Furthermore, AHR shRNA promotes the expression of E2F1 and MYCN in NB cells. These findings suggest that AHR is one of the upstream regulators of MYCN. Through the modulation of E2F1, AHR regulates MYCN gene expression, which may in turn affect NB differentiation.

  18. Cell and biomolecule delivery for tissue repair and regeneration in the central nervous system.

    Science.gov (United States)

    Elliott Donaghue, Irja; Tam, Roger; Sefton, Michael V; Shoichet, Molly S

    2014-09-28

    Tissue engineering frequently involves cells and scaffolds to replace damaged or diseased tissue. It originated, in part, as a means of effecting the delivery of biomolecules such as insulin or neurotrophic factors, given that cells are constitutive producers of such therapeutic agents. Thus cell delivery is intrinsic to tissue engineering. Controlled release of biomolecules is also an important tool for enabling cell delivery since the biomolecules can enable cell engraftment, modulate inflammatory response or otherwise benefit the behavior of the delivered cells. We describe advances in cell and biomolecule delivery for tissue regeneration, with emphasis on the central nervous system (CNS). In the first section, the focus is on encapsulated cell therapy. In the second section, the focus is on biomolecule delivery in polymeric nano/microspheres and hydrogels for the nerve regeneration and endogenous cell stimulation. In the third section, the focus is on combination strategies of neural stem/progenitor cell or mesenchymal stem cell and biomolecule delivery for tissue regeneration and repair. In each section, the challenges and potential solutions associated with delivery to the CNS are highlighted.

  19. 14-3-3σ confers cisplatin resistance in esophageal squamous cell carcinoma cells via regulating DNA repair molecules.

    Science.gov (United States)

    Lai, Kenneth K Y; Chan, Kin Tak; Choi, Mei Yuk; Wang, Hector K; Fung, Eva Y M; Lam, Ho Yu; Tan, Winnie; Tung, Lai Nar; Tong, Daniel K H; Sun, Raymond W Y; Lee, Nikki P; Law, Simon

    2016-02-01

    Esophageal squamous cell carcinoma (ESCC) is the predominant type of esophageal cancer in Asia. Cisplatin is commonly used in chemoradiation for unresectable ESCC patients. However, the treatment efficacy is diminished in patients with established cisplatin resistance. To understand the mechanism leading to the development of cisplatin resistance in ESCC, we compared the proteomes from a cisplatin-resistant HKESC-2R cell line with its parental-sensitive counterpart HKESC-2 to identify key molecule involved in this process. Mass spectrometry analysis detected 14-3-3σ as the most abundant molecule expressed exclusively in HKESC-2R cells, while western blot result further validated it to be highly expressed in HKESC-2R cells when compared to HKESC-2 cells. Ectopic expression of 14-3-3σ increased cisplatin resistance in HKESC-2 cells, while its suppression sensitized SLMT-1 cells to cisplatin. Among the molecules involved in drug detoxification, drug transportation, and DNA repair, the examined DNA repair molecules HMGB1 and XPA were found to be highly expressed in HKESC-2R cells with high 14-3-3σ expression. Subsequent manipulation of 14-3-3σ by both overexpression and knockdown approaches concurrently altered the expression of HMGB1 and XPA. 14-3-3σ, HMGB1, and XPA were preferentially expressed in cisplatin-resistant SLMT-1 cells when compared to those more sensitive to cisplatin. In ESCC patients with poor response to cisplatin-based chemoradiation, their pre-treatment tumors expressed higher expression of HMGB1 than those with response to such treatment. In summary, our results demonstrate that 14-3-3σ induces cisplatin resistance in ESCC cells and that 14-3-3σ-mediated cisplatin resistance involves DNA repair molecules HMGB1 and XPA. Results from this study provide evidences for further work in researching the potential use of 14-3-3σ and DNA repair molecules HMGB1 and XPA as biomarkers and therapeutic targets for ESCC.

  20. Repair of spinal cord injury by neural stem cells modified with BDNF gene in rats

    Institute of Scientific and Technical Information of China (English)

    Wei LI; Wen-Qin CAI; Cheng-Ren LI

    2006-01-01

    Objective To explore repair of spinal cord injury by neural stem cells (NSCs) modified with brain derived neurotrophic factor (BDNF) gene (BDNF-NSCs) in rats. Methods Neural stem cells modified with BDNF gene were transplanted into the complete transection site of spinal cord at the lumbar 4 (L4) level in rats. Motor function of rats'hind limbs was observed and HE and X-gal immunocytochemical staining, in situ hybridization, and retrograde HRP tracing were also performed. Results BDNF-NSCs survived and integrated well with host spinal cord. In the transplant group, some X-gal positive, NF-200 positive, GFAP positive, BDNF positive, and BDNF mRNA positive cells, and many NF-200 positive nerve fibers were observed in the injury site. Retrograde HRP tracing through sciatic nerve showed some HRP positive cells and nerve fibers near the rostral side of the injury one month after transplant and with time, they increased in number. Examinations on rats' motor function and behavior demonstrated that motor function of rats' hind limbs improved better in the transplant group than the injury group. Conclusion BDNF-NSCs can survive, differentiate,and partially integrate with host spinal cord, and they significantly ameliorate rats ' motor function of hind limbs, indicating their promising role in repairing spinal cord injury.

  1. Autologous tendon-derived cell-seeded nanofibrous scaffolds improve rotator cuff repair in an age-dependent fashion.

    Science.gov (United States)

    Huegel, Julianne; Kim, Dong Hwa; Cirone, James M; Pardes, Adam M; Morris, Tyler R; Nuss, Courtney A; Mauck, Robert L; Soslowsky, Louis J; Kuntz, Andrew F

    2017-06-01

    Rotator cuff tendon tears are one of the most common shoulder pathologies, especially in the aging population. Due to a poor healing response and degenerative changes associated with aging, rotator cuff repair failure remains common. Although cell-based therapies to augment rotator cuff repair appear promising, it is unknown whether the success of such a therapy is age-dependent. We hypothesized that autologous cell therapy would improve tendon-to-bone healing across age groups, with autologous juvenile cells realizing the greatest benefit. In this study, juvenile, adult, and aged rats underwent bilateral supraspinatus tendon repair with augmentation of one shoulder with autologous tendon-derived cell-seeded polycaprolactone scaffolds. At 8 weeks, shoulders treated with cells in both juvenile and aged animals exhibited increased cellularity, increased collagen organization, and improved mechanical properties. No changes between treated and control limbs were seen in adult rats. These findings suggest that cell delivery during supraspinatus repair initiates earlier matrix remodeling in juvenile and aged animals. This may be due to the relative "equilibrium" of adult tendon tissue with regards to catabolic and anabolic processes, contrasted with actively growing juvenile tendons and degenerative aged tendons. This study demonstrates the potential for autologous cell-seeded scaffolds to improve repairs in both the juvenile and aged population. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:1250-1257, 2017. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  2. Reversing and Repairing Microstructure Degradation in Solid Oxide Cells During Operation

    DEFF Research Database (Denmark)

    Graves, Christopher R.

    2013-01-01

    The elevated operating temperature of solid oxide electrochemical cells (SOCs) can lead to long-term degradation of cell components due to instability of materials and microstructures. However, this unique possibility for microstructural changes to occur can also be advantageously exploited...... to counteract performance loss, by careful control of operating parameters and cell design. This paper describes four recently discovered methods of in situ reversal or repair of microstructure degradation: (1) The newest method is the elimination of severe electrolysis-induced degradation at high current...... density by reversible battery-like operation, cycling between electrolysis mode and fuel-cell mode. Also reported are new examples of beneficial effects of (2) redox cycling, (3) exsolution of nano-catalysts, and (4) high cathodic polarization, all of which can be used to maintain or even improve...

  3. Schwann Cells Transplantation Promoted and the Repair of Brain Stem Injury in Rats

    Institute of Scientific and Technical Information of China (English)

    HONG WAN; YI-HUA AN; MEI-ZHEN SUN; YA-ZHUO ZHANG; ZHONG-CHENG WANG

    2003-01-01

    To explore the possibility of Schwann cells transplantation to promote the repair of injured brain stem reticular structure in rats. Methods Schwann cells originated from sciatic nerves of 1 to 2-day-old rats were expanded and labelled by BrdU in vitro, transplanted into rat brain stem reticular structure that was pre-injured by electric needle stimulus. Immunohistochemistry and myelin-staining were used to investigate the expression of BrdU, GAP-43 and new myelination respectively. Results BrdU positive cells could be identified for up to 8 months and their number increased by about 23%, which mainly migrated toward injured ipsilateral cortex. The GAP-43expression reached its peak in 1 month after transplantation and was significantly higher than that in the control group. New myelination could be seen in destructed brain stem areas. Conclusion The transplantation of Schwann cells can promote the restoration of injured brain stem reticular structure.

  4. DNA damage and repair in white blood cells at occupational exposure

    Energy Technology Data Exchange (ETDEWEB)

    Georgieva, R T; Zaharieva, E K; Rupova, I M; Acheva, A R; Nikolov, V N [Department of Radiobiology, National Center of Radiobiology and Radiation Protection, Sofia, 1756 (Bulgaria)], E-mail: r.georgieva@ncrrp.org

    2008-02-01

    : The present work was aimed at finding appropriate biomarkers applicable in molecular epidemiological surveys of occupationally exposed individuals and/or population in order to prove low dose effects. Blood samples were taken from NPP workers, in the 'strict regimen' area (exposed group) and from the administration staff (control group). The spontaneous and induced (exposed to a challenge dose of 2,0 Gy gamma irradiation) DNA repair synthesis in leucocytes, the level of DNA damage by single cell gel-electrophoresis in lymphocytes and the concentration of malonedialdehyde in blood serum, were analyzed. A significant decrease of potentially lethal damage in leucocytes as well as reduction of DNA double strand breaks level in lymphocytes of persons with 'mean annual dose' lower or equal to 5 mSv/a was found, compared to the control group. A higher repair capacity corresponding to elevated protein synthesis after a challenging dose of 2,0 Gy gamma rays and a significant decrease in the level of oxidative stress in the blood plasma were established in persons from the same group. The present investigation showed that annual doses not higher than twice the natural radiation background exert positive effects on DNA damage and repair, increase cellular resistance and decrease oxidative stress.

  5. Mutation mismatch repair gene deletions in diffuse large B-cell lymphoma.

    Science.gov (United States)

    Couronné, Lucile; Ruminy, Philippe; Waultier-Rascalou, Agathe; Rainville, Vinciane; Cornic, Marie; Picquenot, Jean-Michel; Figeac, Martin; Bastard, Christian; Tilly, Hervé; Jardin, Fabrice

    2013-05-01

    To further unravel the molecular pathogenesis of diffuse large B-cell lymphoma (DLBCL), we performed high-resolution comparative genomic hybridization on lymph node biopsies from 70 patients. With this strategy, we identified microdeletions of genes involved in the mutation mismatch repair (MMR) pathway in two samples. The first patient presented with a homozygous deletion of MSH2-MSH6 due to duplication of an unbalanced pericentric inversion of chromosome 2. The other case showed a PMS2 heterozygous deletion. PMS2 and MSH2-MSH6 abnormalities, respectively, resulted in a decrease and complete loss of gene expression. However, unlike tumors associated with the hereditary non-polyposis colorectal cancer syndrome or immunodeficiency-related lymphomas, no microsatellite instability was detected. Mutational profiles revealed especially in one patient an aberrant hypermutation without a clear activation-induced cytidine deaminase signature, indicating a breakdown of the high-fidelity repair in favor of the error-prone repair pathway. Our findings suggest that in a rare subset of patients, inactivation of the genes of the MMR pathway is likely an important step in the molecular pathogenesis of DLBCL and does not involve the same molecular mechanisms as other common neoplasms with MMR deficiency.

  6. CtIP-BRCA1 modulates the choice of DNA double-strand break repair pathway throughout the cell cycle

    OpenAIRE

    Yun, Maximina H.; Hiom, Kevin

    2009-01-01

    The repair of DNA double-strand breaks (DSB) is tightly regulated during the cell cycle. In G1 phase, the absence of a sister chromatid means that repair of DSB occurs through non-homologous end-joining (NHEJ) or microhomology-mediated end-joining (MMEJ)1. These pathways often involve loss of DNA sequences at the break site and are therefore error-prone. In late S and G2 phases, even though DNA end-joining pathways remain functional2, there is an increase in repair of DSB by homologous recomb...

  7. Tissue engineering and the use of stem/progenitor cells for airway epithelium repair

    Directory of Open Access Journals (Sweden)

    GM Roomans

    2010-06-01

    Full Text Available Stem/progenitor cells can be used to repair defects in the airway wall, resulting from e.g., tumors, trauma, tissue reactions following long-time intubations, or diseases that are associated with epithelial damage. Several potential sources of cells for airway epithelium have been identified. These can be divided into two groups. The first group consists of endogenous progenitor cells present in the respiratory tract. This group can be subdivided according to location into (a a ductal cell type in the submucosal glands of the proximal trachea, (b basal cells in the intercartilaginous zones of the lower trachea and bronchi, (c variant Clara cells (Clarav-cells in the bronchioles and (d at the junctions between the bronchioles and the alveolar ducts, and (e alveolar type II cells. This classification of progenitor cell niches is, however, controversial. The second group consists of exogenous stem cells derived from other tissues in the body. This second group can be subdivided into: (a embryonic stem (ES cells, induced pluripotent stem (iPS cells, or amniotic fluid stem cells, (b side-population cells from bone marrow or epithelial stem cells present in bone marrow or circulation and (c fat-derived mesenchymal cells. Airway epithelial cells can be co-cultured in a system that includes a basal lamina equivalent, extracellular factors from mesenchymal fibroblasts, and in an air-liquid interface system. Recently, spheroid-based culture systems have been developed. Several clinical applications have been suggested: cystic fibrosis, acute respiratory distress syndrome, chronic obstructive lung disease, pulmonary fibrosis, pulmonary edema, and pulmonary hypertension. Clinical applications so far are few, but include subglottic stenosis, tracheomalacia, bronchiomalacia, and emphysema.

  8. HORSE SPECIES SYMPOSIUM: Use of mesenchymal stem cells in fracture repair in horses.

    Science.gov (United States)

    Govoni, K E

    2015-03-01

    Equine bone fractures are often catastrophic, potentially fatal, and costly to repair. Traditional methods of healing fractures have limited success, long recovery periods, and a high rate of reinjury. Current research in the equine industry has demonstrated that stem cell therapy is a promising novel therapy to improve fracture healing and reduce the incidence of reinjury; however, reports of success in horses have been variable and limited. Stem cells can be derived from embryonic, fetal, and adult tissue. Based on the ease of collection, opportunity for autologous cells, and proven success in other models, adipose- or bone marrow-derived mesenchymal stem cells (MSC) are often used in equine therapies. Methods for isolation, proliferation, and differentiation of MSC are well established in rodent and human models but are not well characterized in horses. There is recent evidence that equine bone marrow MSC are able to proliferate in culture for several passages in the presence of autologous and fetal bovine serum, which is important for expansion of cells. Mesenchymal stem cells have the capacity to differentiate into osteoblasts, the bone forming cells, and this complex process is regulated by a number of transcription factors including runt-related transcription factor 2 (Runx2) and osterix (Osx). However, it has not been well established if equine MSC are regulated in a similar manner. The data presented in this review support the view that equine bone marrow MSC are regulated by the same transcription factors that control the differentiation of rodent and human MSC into osteoblasts. Although stem cell therapy is promising in equine bone repair, additional research is needed to identify optimal methods for reintroduction and potential manipulations to improve their ability to form new bone.

  9. Strategies to stimulate mobilization and homing of endogenous stem and progenitor cells for bone tissue repair

    Directory of Open Access Journals (Sweden)

    Marietta eHerrmann

    2015-06-01

    Full Text Available The gold standard for the treatment of critical sized bone defects is autologous or allogenic bone graft. This has several limitations including donor site morbidity and the restricted supply of graft material. Cell-based tissue engineering strategies represent an alternative approach. Mesenchymal stem cells (MSCs have been considered as a source of osteoprogenitor cells. More recently, focus has been placed on the use of endothelial progenitor cells (EPCs, since vascularization is a critical step in bone healing. Although many of these approaches have demonstrated effectiveness for bone regeneration, cell-based therapies require time consuming and cost expensive in vitro cell expansion procedures. Accordingly, research is becoming increasingly focused on the homing and stimulation of native cells. The stromal cell-derived factor 1 (SDF-1 – CXCR4 axis has been shown to be critical for the recruitment of MSCs and EPCs. Vascular endothelial growth factor (VEGF is a key factor in angiogenesis and has been targeted in many studies. Here, we present an overview of the different approaches for delivering homing factors to the defect site by absorption or incorporation to biomaterials, gene therapy or via genetically manipulated cells. We further review strategies focusing on the stimulation of endogenous cells to support bone repair. Finally, we discuss the major challenges in the treatment of critical size bone defects and fracture non-unions.

  10. Recombination-dependent deletion formation in mammalian cells deficient in the nucleotide excision repair gene ERCC1

    OpenAIRE

    Sargent, R. Geoffrey; Rolig, Rhonda L.; Kilburn, April E.; Adair, Gerald M.; Wilson, John H.; Nairn, Rodney S.

    1997-01-01

    Nucleotide excision repair proteins have been implicated in genetic recombination by experiments in Saccharomyces cerevisiae and Drosophila melanogaster, but their role, if any, in mammalian cells is undefined. To investigate the role of the nucleotide excision repair gene ERCC1, the hamster homologue to the S. cerevisiae RAD10 gene, we disabled the gene by targeted knockout. Partial tandem duplications of the adenine phosphoribosyltransferase (APRT) gene then were constructed at the endogeno...

  11. Detection of abnormalities in the superficial zone of cartilage repaired using a tissue engineered construct derived from synovial stem cells

    OpenAIRE

    Ando, W.; FUJIE, H; Moriguchi, Y.; Nansai, R.; Shimomura, K.; DA Hart; Yoshikawa, H; Nakamura, N.

    2012-01-01

    The present study investigated the surface structure and mechanical properties of repair cartilage generated from a tissue engineered construct (TEC) derived from synovial mesenchymal stem cells at six months post-implantation compared to those of uninjured cartilage. TEC-mediated repair tissue was cartilaginous with Safranin O staining, and had comparable macro-scale compressive properties with uninjured cartilage. However, morphological assessments revealed that the superficial zone of TEC-...

  12. Synthetic lethal targeting of DNA double strand break repair deficient cells by human apurinic/apyrimidinic endonuclease (APE1) inhibitors

    OpenAIRE

    Sultana, Rebeka; McNeill, Daniel R.; Abbotts, Rachel; Mohammed, Mohammed Z.; Zdzienicka, Małgorzata Z.; Qutob, Haitham; Seedhouse, Claire; Charles A. Laughton; Fischer, Peter M.; Patel, Poulam M.; Wilson, David M.; Madhusudan, Srinivasan

    2012-01-01

    An apurinic/apyrimidinic (AP) site is an obligatory cytotoxic intermediate in DNA Base Excision Repair (BER) that is processed by human AP endonuclease 1 (APE1). APE1 is essential for BER and an emerging drug target in cancer. We have isolated novel small molecule inhibitors of APE1. In the current study we have investigated the ability of APE1 inhibitors to induce synthetic lethality in a panel of DNA double strand break (DSB) repair deficient and proficient cells; a) Chine...

  13. Lifespan differences in hematopoietic stem cells are due to imperfect repair and unstable mean-reversion.

    Directory of Open Access Journals (Sweden)

    Hans B Sieburg

    2013-04-01

    Full Text Available The life-long supply of blood cells depends on the long-term function of hematopoietic stem cells (HSCs. HSCs are functionally defined by their multi-potency and self-renewal capacity. Because of their self-renewal capacity, HSCs were thought to have indefinite lifespans. However, there is increasing evidence that genetically identical HSCs differ in lifespan and that the lifespan of a HSC is predetermined and HSC-intrinsic. Lifespan is here defined as the time a HSC gives rise to all mature blood cells. This raises the intriguing question: what controls the lifespan of HSCs within the same animal, exposed to the same environment? We present here a new model based on reliability theory to account for the diversity of lifespans of HSCs. Using clonal repopulation experiments and computational-mathematical modeling, we tested how small-scale, molecular level, failures are dissipated at the HSC population level. We found that the best fit of the experimental data is provided by a model, where the repopulation failure kinetics of each HSC are largely anti-persistent, or mean-reverting, processes. Thus, failure rates repeatedly increase during population-wide division events and are counteracted and decreased by repair processes. In the long-run, a crossover from anti-persistent to persistent behavior occurs. The cross-over is due to a slow increase in the mean failure rate of self-renewal and leads to rapid clonal extinction. This suggests that the repair capacity of HSCs is self-limiting. Furthermore, we show that the lifespan of each HSC depends on the amplitudes and frequencies of fluctuations in the failure rate kinetics. Shorter and longer lived HSCs differ significantly in their pre-programmed ability to dissipate perturbations. A likely interpretation of these findings is that the lifespan of HSCs is determined by preprogrammed differences in repair capacity.

  14. Modulation of wound healing and scar formation by MG53 protein-mediated cell membrane repair.

    Science.gov (United States)

    Li, Haichang; Duann, Pu; Lin, Pei-Hui; Zhao, Li; Fan, Zhaobo; Tan, Tao; Zhou, Xinyu; Sun, Mingzhai; Fu, Minghuan; Orange, Matthew; Sermersheim, Matthew; Ma, Hanley; He, Duofen; Steinberg, Steven M; Higgins, Robert; Zhu, Hua; John, Elizabeth; Zeng, Chunyu; Guan, Jianjun; Ma, Jianjie

    2015-10-02

    Cell membrane repair is an important aspect of physiology, and disruption of this process can result in pathophysiology in a number of different tissues, including wound healing, chronic ulcer and scarring. We have previously identified a novel tripartite motif family protein, MG53, as an essential component of the cell membrane repair machinery. Here we report the functional role of MG53 in the modulation of wound healing and scarring. Although MG53 is absent from keratinocytes and fibroblasts, remarkable defects in skin architecture and collagen overproduction are observed in mg53(-/-) mice, and these animals display delayed wound healing and abnormal scarring. Recombinant human MG53 (rhMG53) protein, encapsulated in a hydrogel formulation, facilitates wound healing and prevents scarring in rodent models of dermal injuries. An in vitro study shows that rhMG53 protects against acute injury to keratinocytes and facilitates the migration of fibroblasts in response to scratch wounding. During fibrotic remodeling, rhMG53 interferes with TGF-β-dependent activation of myofibroblast differentiation. The resulting down-regulation of α smooth muscle actin and extracellular matrix proteins contributes to reduced scarring. Overall, these studies establish a trifunctional role for MG53 as a facilitator of rapid injury repair, a mediator of cell migration, and a modulator of myofibroblast differentiation during wound healing. Targeting the functional interaction between MG53 and TGF-β signaling may present a potentially effective means for promoting scarless wound healing. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Specific targeted gene repair using single-stranded DNA oligonucleotides at an endogenous locus in mammalian cells uses homologous recombination.

    Science.gov (United States)

    McLachlan, Jennifer; Fernandez, Serena; Helleday, Thomas; Bryant, Helen E

    2009-12-03

    The feasibility of introducing point mutations in vivo using single-stranded DNA oligonucleotides (ssON) has been demonstrated but the efficiency and mechanism remain elusive and potential side effects have not been fully evaluated. Understanding the mechanism behind this potential therapy may help its development. Here, we demonstrate the specific repair of an endogenous non-functional hprt gene by a ssON in mammalian cells, and show that the frequency of such an event is enhanced when cells are in S-phase of the cell cycle. A potential barrier in using ssONs as gene therapy could be non-targeted mutations or gene rearrangements triggered by the ssON. Both the non-specific mutation frequencies and the frequency of gene rearrangements were largely unaffected by ssONs. Furthermore, we find that the introduction of a mutation causing the loss of a functional endogenous hprt gene by a ssON occurred at a similarly low but statistically significant frequency in wild type cells and in cells deficient in single strand break repair, nucleotide excision repair and mismatch repair. However, this mutation was not induced in XRCC3 mutant cells deficient in homologous recombination. Thus, our data suggest ssON-mediated targeted gene repair is more efficient in S-phase and involves homologous recombination.

  16. Macrophage Recruitment and Epithelial Repair Following Hair Cell Injury in the Mouse Utricle

    Directory of Open Access Journals (Sweden)

    Tejbeer eKaur

    2015-04-01

    Full Text Available The sensory organs of the inner ear possess resident populations of macrophages, but the function of those cells is poorly understood. In many tissues, macrophages participate in the removal of cellular debris after injury and can also promote tissue repair. The present study examined injury-evoked macrophage activity in the mouse utricle. Experiments used transgenic mice in which the gene for the human diphtheria toxin receptor (huDTR was inserted under regulation of the Pou4f3 promoter. Hair cells in such mice can be selectively lesioned by systemic treatment with diphtheria toxin (DT. In order to visualize macrophages, Pou4f3-huDTR mice were crossed with a second transgenic line, in which one or both copies of the gene for the fractalkine receptor CX3CR1 were replaced with a gene for GFP. Such mice expressed GFP in all macrophages, and mice that were CX3CR1GFP/GFP lacked the necessary receptor for fractalkine signaling. Treatment with DT resulted in the death of ~70% of utricular hair cells within seven days, which was accompanied by increased numbers of macrophages within the utricular sensory epithelium. Many of these macrophages appeared to be actively engulfing hair cell debris, indicating that macrophages participate in the process of ‘corpse removal’ in the mammalian vestibular organs. However, we observed no apparent differences in injury-evoked macrophage numbers in the utricles of CX3CR1+/GFP mice vs. CX3CR1GFP/GFP mice, suggesting that fractalkine signaling is not necessary for macrophage recruitment in these sensory organs. Finally, we found that repair of sensory epithelia at short times after DT-induced hair cell lesions was mediated by relatively thin cables of F-actin. After 56 days recovery, however, all cell-cell junctions were characterized by very thick actin cables.

  17. Strategies for endogenous spinal cord repair: HPMA hydrogel to recruit migrating endogenous stem cells.

    Science.gov (United States)

    Espinosa-Jeffrey, Araceli; Oregel, Karlos; Wiggins, Laurent; Valera, Remelyn; Bosnoyan, Kathrin; Agbo, Chioma; Awosika, Oluwole; Zhao, Paul M; de Vellis, Jean; Woerly, Stéphane

    2012-01-01

    Injury to the spinal cord disrupts ascending and descending axonal pathways and causes tissue damage with a subsequent limited cellular regeneration. Successful treatment would encompass the restoration of the cytoarchitecture, homeostasis and function all in dear need. Transplantation-based treatments using exogenous cells are the most favoured approach. Yet, with the advent of the stem cell concept and continuous progress in the field it became clear that the endogenous potential for repair is greater than previously thought. As an alternative to neural grafting, we and other researchers have aimed at understanding what are the elements needed for a successful repair with self progenitors that would give rise to the cell types needed to restore function of the central nervous system. Some studies involve both scaffolds and cell grafts. Here we describe studies on spinal cord repair using what we call "endogenous tissue engineering for regenerative medicine". The approach involves a hydrogel that mimics the natural milieu where endogenous pre-existing and newly formed cells populate the gel progressively allowing for the integration of CNS self populations leading to a successful recovery of function. Highlight aspects learned from this type of studies are that: Endogenous reconstruction of the injured spinal cord is possible by using the adequate support. The contribution of nestin-expressing progenitors to spinal cord regeneration is continuous and substantial both, in the reconstructed segment as well as, along the distal and caudal segments of the reconstructed spinal cord. Most of these cells appear to have been in a quiescent state until the injury occurred and only a small fraction of these neural progenitors was produced via cell proliferation. The hydrogel combined with exercise was necessary and sufficient to restore locomotor function in cats that underwent spinal transaction followed by reconstructive surgery. This recovery of function was first seen

  18. Using sediment microbial fuel cells (SMFCs) for bioremediation of polycyclic aromatic hydrocarbons (PAHs).

    Science.gov (United States)

    Sherafatmand, Mohammad; Ng, How Yong

    2015-11-01

    In this study, a sediment microbial fuel cell (SMFC) was explored to bioremediate polycyclic aromatic hydrocarbons (PAHs) in water originated from soil. The results showed consistent power generations of 6.02±0.34 and 3.63±0.37 mW/m(2) under an external resistance of 1500 Ω by the aerobic and anaerobic SMFC, respectively. Although the power generations were low, they had relatively low internal resistances (i.e., 436.6±69.4 and 522.1±1.8 Ω for the aerobic and anaerobic SMFC, respectively) in comparison with the literature. Nevertheless, the significant benefit of this system was its bioremediation capabilities, achieving 41.7%, 31.4% and 36.2% removal of naphthalene, acenaphthene and phenanthrene, respectively, in the aerobic environment and 76.9%, 52.5% and 36.8%, respectively, in the anaerobic environment. These results demonstrated the ability of SMFCs in stimulating microorganisms for bioremediation of complex and recalcitrant PAHs.

  19. Role of DNA repair machinery and p53 in the testicular germ cell cancer: a review.

    Science.gov (United States)

    Romano, Francesco Jacopo; Rossetti, Sabrina; Conteduca, Vincenza; Schepisi, Giuseppe; Cavaliere, Carla; Di Franco, Rossella; La Mantia, Elvira; Castaldo, Luigi; Nocerino, Flavia; Ametrano, Gianluca; Cappuccio, Francesca; Malzone, Gabriella; Montanari, Micaela; Vanacore, Daniela; Quagliariello, Vincenzo; Piscitelli, Raffaele; Pepe, Maria Filomena; Berretta, Massimiliano; D'Aniello, Carmine; Perdonà, Sisto; Muto, Paolo; Botti, Gerardo; Ciliberto, Gennaro; Veneziani, Bianca Maria; De Falco, Francesco; Maiolino, Piera; Caraglia, Michele; Montella, Maurizio; De Giorgi, Ugo; Facchini, Gaetano

    2016-12-20

    Notwithstanding the peculiar sensitivity to cisplatin-based treatment, resulting in a very high percentage of cures even in advanced stages of the disease, still we do not know the biological mechanisms that make Testicular Germ Cell Tumor (TGCT) "unique" in the oncology scene. p53 and MDM2 seem to play a pivotal role, according to several in vitro observations, but no correlation has been found between their mutational or expression status in tissue samples and patients clinical outcome. Furthermore, other players seem to be on stage: DNA Damage Repair Machinery (DDR) , especially Homologous Recombination (HR) proteins, above all Ataxia Telangiectasia Mutated (ATM), cooperates with p53 in response to DNA damage, activating apoptotic cascade and contributing to cell "fate". Homologous Recombination deficiency has been assumed to be a Germ Cell Tumor characteristic underlying platinum-sensitivity, whereby Poly(ADP-ribose) polymerase (PARP), an enzyme involved in HR DNA repair, is an intriguing target: PARP inhibitors have already entered in clinical practice of other malignancies and trials are recruiting TGCT patients in order to validate their role in this disease. This paper aims to summarize evidence, trying to outline an overview of DDR implications not only in TGCT curability, but also in resistance to chemotherapy.

  20. Transcriptional and post-transcriptional regulation of nucleotide excision repair genes in human cells

    Energy Technology Data Exchange (ETDEWEB)

    Lefkofsky, Hailey B. [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Veloso, Artur [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Bioinformatics Program, Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI (United States); Ljungman, Mats, E-mail: ljungman@umich.edu [Translational Oncology Program, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI (United States); Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, MI (United States)

    2015-06-15

    Nucleotide excision repair (NER) removes DNA helix-distorting lesions induced by UV light and various chemotherapeutic agents such as cisplatin. These lesions efficiently block the elongation of transcription and need to be rapidly removed by transcription-coupled NER (TC-NER) to avoid the induction of apoptosis. Twenty-nine genes have been classified to code for proteins participating in nucleotide excision repair (NER) in human cells. Here we explored the transcriptional and post-transcriptional regulation of these NER genes across 13 human cell lines using Bru-seq and BruChase-seq, respectively. Many NER genes are relatively large in size and therefore will be easily inactivated by UV-induced transcription-blocking lesions. Furthermore, many of these genes produce transcripts that are rather unstable. Thus, these genes are expected to rapidly lose expression leading to a diminished function of NER. One such gene is ERCC6 that codes for the CSB protein critical for TC-NER. Due to its large gene size and high RNA turnover rate, the ERCC6 gene may act as dosimeter of DNA damage so that at high levels of damage, ERCC6 RNA levels would be diminished leading to the loss of CSB expression, inhibition of TC-NER and the promotion of cell death.

  1. Combination of edaravone and neural stem cell transplantation repairs injured spinal cord in rats.

    Science.gov (United States)

    Song, Y Y; Peng, C G; Ye, X B

    2015-12-29

    This study sought to observe the effect of the combination of edaravone and neural stem cell (NSC) transplantation on the repair of complete spinal cord transection in rats. Eighty adult female Sprague-Dawley (SD) rats were used to establish the injury model of complete spinal cord transection at T9. Animals were divided randomly into four groups (N = 20 each): control, edaravone, transplantation, and edaravone + transplantation. The recovery of spinal function was evaluated with the Basso, Beattie, Bresnahan (BBB) rating scale on days 1, 3, and 7 each week after the surgery. After 8 weeks, the BBB scores of the control, edaravone, transplantation, and combination groups were 4.21 ± 0.11, 8.46 ± 0.1, 8.54 ± 0.13, and 11.21 ± 0.14, respectively. At 8 weeks after surgery, the spinal cord was collected; the survival and transportation of transplanted cells were observed with PKH-26 labeling, and the regeneration and distribution of spinal nerve fibers with fluorescent-gold (FG) retrograde tracing. Five rats died due to the injury. PKH-26-labeled NSCs had migrated into the spinal cord. A few intact nerve fibers and pyramidal neurons passed the injured area in the transplantation and combination groups. The numbers of PKH-26-labeled cells and FG-labeled nerve fibers were in the order: combination group > edaravone group and transplantation group > control group (P injured areas; edaravone with NSC transplantation can improve the effectiveness of spinal cord injury repair in rats.

  2. DNA repair and replication links to pluripotency and differentiation capacity of pig iPS cells

    Science.gov (United States)

    Song, Lipu; Fan, Anran; Zhang, Sheng; Wang, Jianyu; Fan, Nana; Liu, Na; Ye, Xiaoying; Fu, Haifeng; Zhou, Zhongcheng; Wang, Yong; Wei, Hong; Liu, Zhonghua; Li, Ziyi; Lai, Liangxue; Wang, Xumin; Liu, Lin

    2017-01-01

    Pigs are proposed to be suitable large animal models for test of the efficacy and safety of induced pluripotent stem cells (iPSCs) for stem cell therapy, but authentic pig ES/iPS cell lines with germline competence are rarely produced. The pathways or signaling underlying the defective competent pig iPSCs remain poorly understood. By improving induction conditions using various small chemicals, we generated pig iPSCs that exhibited high pluripotency and differentiation capacity that can contribute to chimeras. However, their potency was reduced with increasing passages by teratoma formation test, and correlated with declined expression levels of Rex1, an important marker for naïve state. By RNA-sequencing analysis, genes related to WNT signaling were upregulated and MAPK signaling and TGFβ pathways downregulated in pig iPSCs compared to fibroblasts, but they were abnormally expressed during passages. Notably, pathways involving in DNA repair and replication were upregulated at early passage, but downregulated in iPSCs during prolonged passage in cluster with fibroblasts. Our data suggests that reduced DNA repair and replication capacity links to the instability of pig iPSCs. Targeting these pathways may facilitate generation of truly pluripotent pig iPSCs, with implication in translational studies. PMID:28253351

  3. The recombination protein RAD52 cooperates with the excision repair protein OGG1 for the repair of oxidative lesions in mammalian cells

    DEFF Research Database (Denmark)

    de Souza-Pinto, Nadja C; Maynard, Scott; Hashiguchi, Kazunari;

    2009-01-01

    activities and RAD52 stimulates OGG1 incision activity, likely increasing its turnover rate. RAD52 colocalizes with OGG1 after oxidative stress to cultured cells, but not after the direct induction of double-strand breaks by ionizing radiation. Human cells depleted of RAD52 via small interfering RNA...... to repair oxidative DNA damage and enhances the cellular resistance to oxidative stress. Our observations suggest a coordinated action between these proteins that may be relevant when oxidative lesions positioned close to strand breaks impose a hindrance to RAD52 catalytic activities....

  4. Stem cells for liver tissue repair:Current knowledge and perspectives

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Stem cells from extra- or intrahepatic sources have been recently characterized and their usefulness for the generation of hepatocyte-like lineages has been demonstrated.Therefore,they are being increasingly considered for future applications in liver cell therapy.In that field,liver cell transplantation is currently regarded as a possible alternative to whole organ transplantation,while stem cells possess theoretical advantages on hepatocytes as they display higher in vitro culture performances and could be used in autologous transplant procedures.However,the current research on the hepatic fate of stem cells is still facing difficulties to demonstrate the acquisition of a full mature hepatocyte phenotype,both in vitro and in vivo.Furthermore,the lack of obvious demonstration of in vivo hepatocyte-like cell functionality remains associated to low repopulation rates obtained after current transplantation procedures.The present review focuses on the current knowledge of the stern cell potential for liver therapy.We discuss the characteristics of the principal cell candidates and the methods to demonstrate their hepatic potential in vitro and in vivo.We finally address the question of the future clinical applications of stem cells for liver tissue repair and the technical aspects that remain to be investigated.

  5. Repair of injured spinal cord using biomaterial scaffolds and stem cells.

    Science.gov (United States)

    Shrestha, Bikesh; Coykendall, Katherine; Li, Yongchao; Moon, Alex; Priyadarshani, Priyanka; Yao, Li

    2014-08-01

    The loss of neurons and degeneration of axons after spinal cord injury result in the loss of sensory and motor functions. A bridging biomaterial construct that allows the axons to grow through has been investigated for the repair of injured spinal cord. Due to the hostility of the microenvironment in the lesion, multiple conditions need to be fulfilled to achieve improved functional recovery. A scaffold has been applied to bridge the gap of the lesion as contact guidance for axonal growth and to act as a vehicle to deliver stem cells in order to modify the microenvironment. Stem cells may improve functional recovery of the injured spinal cord by providing trophic support or directly replacing neurons and their support cells. Neural stem cells and mesenchymal stem cells have been seeded into biomaterial scaffolds and investigated for spinal cord regeneration. Both natural and synthetic biomaterials have increased stem cell survival in vivo by providing the cells with a controlled microenvironment in which cell growth and differentiation are facilitated. This optimal multi‒disciplinary approach of combining biomaterials, stem cells, and biomolecules offers a promising treatment for the injured spinal cord.

  6. Erythropoietin responsive cardiomyogenic cells contribute to heart repair post myocardial infarction.

    Science.gov (United States)

    Zafiriou, Maria Patapia; Noack, Claudia; Unsöld, Bernhard; Didie, Michael; Pavlova, Elena; Fischer, Henrike J; Reichardt, Holger M; Bergmann, Martin W; El-Armouche, Ali; Zimmermann, Wolfram-Hubertus; Zelarayan, Laura Cecilia

    2014-09-01

    The role of erythropoietin (Epo) in myocardial repair after infarction remains inconclusive. We observed high Epo receptor (EPOR) expression in cardiac progenitor cells (CPCs). Therefore, we aimed to characterize these cells and elucidate their contribution to myocardial regeneration on Epo stimulation. High EPOR expression was detected during murine embryonic heart development followed by a marked decrease until adulthood. EPOR-positive cells in the adult heart were identified in a CPC-enriched cell population and showed coexpression of stem, mesenchymal, endothelial, and cardiomyogenic cell markers. We focused on the population coexpressing early (TBX5, NKX2.5) and definitive (myosin heavy chain [MHC], cardiac Troponin T [cTNT]) cardiomyocyte markers. Epo increased their proliferation and thus were designated as Epo-responsive MHC expressing cells (EMCs). In vitro, EMCs proliferated and partially differentiated toward cardiomyocyte-like cells. Repetitive Epo administration in mice with myocardial infarction (cumulative dose 4 IU/g) resulted in an increase in cardiac EMCs and cTNT-positive cells in the infarcted area. This was further accompanied by a significant preservation of cardiac function when compared with control mice. Our study characterized an EPO-responsive MHC-expressing cell population in the adult heart. Repetitive, moderate-dose Epo treatment enhanced the proliferation of EMCs resulting in preservation of post-ischemic cardiac function.

  7. EGF receptor signaling blocks aryl hydrocarbon receptor-mediated transcription and cell differentiation in human epidermal keratinocytes

    OpenAIRE

    Sutter, Carrie Hayes; Yin, Hong; Li, Yunbo; Mammen, Jennifer S.; Bodreddigari, Sridevi; Stevens, Gaylene; Cole, Judith A; Sutter, Thomas R.

    2009-01-01

    Dioxin is an extremely potent carcinogen. In highly exposed people, the most commonly observed toxicity is chloracne, a pathological response of the skin. Most of the effects of dioxin are attributed to its activation of the aryl hydrocarbon receptor (AHR), a transcription factor that binds to the Ah receptor nuclear translocator (ARNT) to regulate the transcription of numerous genes, including CYP1A1 and CYP1B1. In cultures of normal human epidermal keratinocytes dioxin accelerates cell diff...

  8. Enhanced infarct myocardium repair mediated by thermosensitive copolymer hydrogel-based stem cell transplantation.

    Science.gov (United States)

    Xia, Yu; Zhu, Kai; Lai, Hao; Lang, Meidong; Xiao, Yan; Lian, Sheng; Guo, Changfa; Wang, Chunsheng

    2015-05-01

    Mesenchymal stem cell (MSC) transplantation by intramyocardial injection has been proposed as a promising therapy strategy for cardiac repair after myocardium infarction. However, low retention and survival of grafted MSCs hinder its further application. In this study, copolymer with N-isopropylacrylamide/acrylic acid/2-hydroxylethyl methacrylate-poly(ɛ-caprolactone) ratio of 88:9.6:2.4 was bioconjugated with type I collagen to construct a novel injectable thermosensitive hydrogel. The injectable and biocompatible hydrogel-mediated MSC transplantation could enhance the grafted cell survival in the myocardium, which contributed to the increased neovascularization, decreased interstitial fibrosis, and ultimately improved heart function to a significantly greater degree than regular MSC transplantation. We suggest that this novel hydrogel has the potential for future stem cell transplantation.

  9. Transplanted Human Umbilical Cord Mesenchymal Stem Cells Facilitate Lesion Repair in B6.Fas Mice

    Directory of Open Access Journals (Sweden)

    Guang-ping Ruan

    2014-01-01

    Full Text Available Background. Systemic lupus erythematosus (SLE is a multisystem disease that is characterized by the appearance of serum autoantibodies. No effective treatment for SLE currently exists. Methods. We used human umbilical cord mesenchymal stem cell (H-UC-MSC transplantation to treat B6.Fas mice. Results. After four rounds of cell transplantation, we observed a statistically significant decrease in the levels of mouse anti-nuclear, anti-histone, and anti-double-stranded DNA antibodies in transplanted mice compared with controls. The percentage of CD4+CD25+Foxp3+ T cells in mouse peripheral blood significantly increased after H-UC-MSC transplantation. Conclusions. The results showed that H-UC-MSCs could repair lesions in B6.Fas mice such that all of the relevant disease indicators in B6.Fas mice were restored to the levels observed in normal C57BL/6 mice.

  10. Enhanced infarct myocardium repair mediated by thermosensitive copolymer hydrogel-based stem cell transplantation

    Science.gov (United States)

    Xia, Yu; Zhu, Kai; Lai, Hao; Lang, Meidong; Xiao, Yan; Lian, Sheng

    2015-01-01

    Mesenchymal stem cell (MSC) transplantation by intramyocardial injection has been proposed as a promising therapy strategy for cardiac repair after myocardium infarction. However, low retention and survival of grafted MSCs hinder its further application. In this study, copolymer with N-isopropylacrylamide/acrylic acid/2-hydroxylethyl methacrylate-poly(ɛ-caprolactone) ratio of 88:9.6:2.4 was bioconjugated with type I collagen to construct a novel injectable thermosensitive hydrogel. The injectable and biocompatible hydrogel-mediated MSC transplantation could enhance the grafted cell survival in the myocardium, which contributed to the increased neovascularization, decreased interstitial fibrosis, and ultimately improved heart function to a significantly greater degree than regular MSC transplantation. We suggest that this novel hydrogel has the potential for future stem cell transplantation. PMID:25432986

  11. Mesenchymal stem cell therapy in osteoarthritis: advanced tissue repair or intervention with smouldering synovial activation?

    Science.gov (United States)

    van Lent, Peter L E M; van den Berg, Wim B

    2013-03-20

    Although it is generally accepted that osteoarthritis is a degenerative condition of the cartilage, other tissues such as synovium in which immunological and inflammatory reactions occur contribute to the development of joint pathology. This sheds new light on the potential mechanism of action of mesenchymal stem cell therapy in osteoarthritis. Rather than tissue repair due to local transformation of injected mesenchymal stem cells to chondrocytes and filling defects in cartilage, such treatment might suppress synovial activation and indirectly ameliorate cartilage damage. Desando and co-workers report in Arthritis Research & Therapy that intra-articular delivery of adipose-derived stem cells attenuates progression of synovial activation and joint destruction in osteoarthritis in an experimental rabbit model. Clinical studies are warranted to see whether this approach might be a novel way to combat development of joint destruction in inflammatory subtypes of osteoarthritis.

  12. Inflammatory cytokines regulate endothelial cell survival and tissue repair functions via NF-κB signaling

    Directory of Open Access Journals (Sweden)

    Kanaji N

    2011-09-01

    Full Text Available Nobuhiro Kanaji1, Tadashi Sato2, Amy Nelson3, Xingqi Wang3, YingJi Li4, Miok Kim5, Masanori Nakanishi6, Hesham Basma3, Joel Michalski3, Maha Farid3, Michael Chandler3, William Pease3, Amol Patil3, Stephen I Rennard3, Xiangde Liu31Division of Hematology, Rheumatology and Respiratory Medicine, Kagawa University, Kagawa, Japan; 2Department of Respiratory Medicine, Juntendo University School of Medicine, Tokyo, Japan; 3Pulmonary and Critical Care Medicine, University of Nebraska Medical Center, Omaha, Nebraska; 4Department of Hygiene and Public Health, Nippon Medical School, Tokyo, Japan; 5Third Department of Internal Medicine, Wakayama Medical University School of Medicine, Wakayama, Japan; 6Department of Internal Medicine, Jeju Medical College, Jeju, Republic of KoreaAbstract: Inflammation contributes to the development of fibrotic and malignant diseases. We assessed the ability of inflammatory cytokines to modulate endothelial cell survival and functions related to tissue repair/remodeling. Treatment with interleukin (IL-1ß or tumor necrosis factor (TNF-α (2 ng/mL led to human pulmonary artery endothelial cells becoming spindle-shaped fibroblast-like cells. However, immunoblot and DNA microarray showed no change in most endothelial and mesenchymal markers. In the presence of IL-1ß or TNF-α, cells were resistant to apoptosis induced by deprivation of serum and growth factor, and were more migratory. In addition, cells treated with IL-1ß or TNF-α contracted collagen gels more robustly. In contrast, transforming growth factor-ß1 did not induce these responses. RNA interference targeting nuclear factor (NF- κB p65 blocked the effects of IL-1ß or TNF-α on cell morphologic change, survival, migration, and collagen gel contraction. These results suggest that endothelial cells may contribute to tissue repair/remodeling via the NF-κB signaling in a milieu of airway inflammation.Keywords: NF-κB, IL-1ß, TNF-α, apoptosis, tissue repair

  13. Autologous, allogeneic, induced pluripotent stem cell or a combination stem cell therapy? Where are we headed in cartilage repair and why: a concise review

    NARCIS (Netherlands)

    Vonk, L.A.; Windt, de T.S.; Slaper-Cortenbach, Ineke C.M.; Saris, D.B.F.

    2015-01-01

    The evolution of articular cartilage repair procedures has resulted in a variety of cell-based therapies that use both autologous and allogeneic mesenchymal stromal cells (MSCs). As these cells are increasingly available and show promising results both in vitro and in vivo, cell-based strategies, wh

  14. Radiosensitisation by pharmacological ascorbate in glioblastoma multiforme cells, human glial cells, and HUVECs depends on their antioxidant and DNA repair capabilities and is not cancer specific.

    Science.gov (United States)

    Castro, M Leticia; McConnell, Melanie J; Herst, Patries M

    2014-09-01

    We previously showed that 5 mM ascorbate radiosensitized early passage radioresistant glioblastoma multiforme (GBM) cells derived from one patient tumor. Here we investigate the sensitivity of a panel of cell lines to 5 mM ascorbate and 6 Gy ionizing radiation, made up of three primary human GBM cells, three GBM cell lines, a human glial cell line, and primary human vascular endothelial cells. The response of different cells lines to ascorbate and/or radiation was determined by measuring viability, colony-forming ability, generation and repair of double-stranded DNA breaks (DSBs), cell cycle progression, antioxidant capacity and generation of reactive oxygen species. Individually, radiation and ascorbate both decreased viability and clonogenicity by inducing DNA damage, but had differential effects on cell cycle progression. Radiation led to G2/M arrest in most cells whereas ascorbate caused accumulation in S phase, which was moderately associated with poor DSB repair. While high dose ascorbate radiosensitized all cell lines in clonogenic assays, the sensitivity to radiation, high dose ascorbate, and combined treatment varied between cell lines. Normal glial cells were similar to GBM cells with respect to free radical scavenging potential and effect of treatment on DNA damage and repair, viability, and clonogenicity. Both GBM cells and normal cells coped equally poorly with oxidative stress caused by radiation and/or high dose ascorbate, dependent primarily on their antioxidant and DSB repair capacity.

  15. Dynamic dependence on ATR and ATM for double-strand break repair in human embryonic stem cells and neural descendants.

    Directory of Open Access Journals (Sweden)

    Bret R Adams

    Full Text Available The DNA double-strand break (DSB is the most toxic form of DNA damage. Studies aimed at characterizing DNA repair during development suggest that homologous recombination repair (HRR is more critical in pluripotent cells compared to differentiated somatic cells in which nonhomologous end joining (NHEJ is dominant. We have characterized the DNA damage response (DDR and quality of DNA double-strand break (DSB repair in human embryonic stem cells (hESCs, and in vitro-derived neural cells. Resolution of ionizing radiation-induced foci (IRIF was used as a surrogate for DSB repair. The resolution of gamma-H2AX foci occurred at a slower rate in hESCs compared to neural progenitors (NPs and astrocytes perhaps reflective of more complex DSB repair in hESCs. In addition, the resolution of RAD51 foci, indicative of active homologous recombination repair (HRR, showed that hESCs as well as NPs have high capacity for HRR, whereas astrocytes do not. Importantly, the ATM kinase was shown to be critical for foci formation in astrocytes, but not in hESCs, suggesting that the DDR is different in these cells. Blocking the ATM kinase in astrocytes not only prevented the formation but also completely disassembled preformed repair foci. The ability of hESCs to form IRIF was abrogated with caffeine and siRNAs targeted against ATR, implicating that hESCs rely on ATR, rather than ATM for regulating DSB repair. This relationship dynamically changed as cells differentiated. Interestingly, while the inhibition of the DNA-PKcs kinase (and presumably non-homologous endjoining [NHEJ] in astrocytes slowed IRIF resolution it did not in hESCs, suggesting that repair in hESCs does not utilize DNA-PKcs. Altogether, our results show that hESCs have efficient DSB repair that is largely ATR-dependent HRR, whereas astrocytes critically depend on ATM for NHEJ, which, in part, is DNA-PKcs-independent.

  16. Production and in vitro evaluation of macroporous, cell-encapsulating alginate fibres for nerve repair.

    Science.gov (United States)

    Lin, Sharon Chien-Yu; Wang, Yiwei; Wertheim, David F; Coombes, Allan G A

    2017-04-01

    The prospects for successful peripheral nerve repair using fibre guides are considered to be enhanced by the use of a scaffold material, which promotes attachment and proliferation of glial cells and axonal regeneration. Macroporous alginate fibres were produced by extraction of gelatin particle porogens from wet spun fibres produced using a suspension of gelatin particles in 1.5% w/v alginate solution. Gelatin loading of the starting suspension of 40.0, 57.0, and 62.5% w/w resulted in gelatin loading of the dried alginate fibres of 16, 21, and 24% w/w respectively. Between 45 and 60% of the gelatin content of hydrated fibres was released in 1h in distilled water at 37°C, leading to rapid formation of a macroporous structure. Confocal laser scanning microscopy (CLSM) and image processing provided qualitative and quantitative analysis of mean equivalent macropore diameter (48-69μm), pore size distribution, estimates of maximum porosity (14.6%) and pore connectivity. CLSM also revealed that gelatin residues lined the macropore cavities and infiltrated into the body of the alginate scaffolds, thus, providing cell adhesion molecules, which are potentially advantageous for promoting growth of glial cells and axonal extension. Macroporous alginate fibres encapsulating nerve cells [primary rat dorsal root ganglia (DRGs)] were produced by wet spinning alginate solution containing dispersed gelatin particles and DRGs. Marked outgrowth was evident over a distance of 150μm at day 11 in cell culture, indicating that pores and channels created within the alginate hydrogel were providing a favourable environment for neurite development. These findings indicate that macroporous alginate fibres encapsulating nerve cells may provide the basis of a useful strategy for nerve repair. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Pim-3 contributes to radioresistance through regulation of the cell cycle and DNA damage repair in pancreatic cancer cells

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    Chen, Xiang-Yuan; Wang, Zhen [Cancer Research Institute, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Li, Bei [Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Zhang, Ying-Jian, E-mail: yjzhang111@aliyun.com [Department of Nuclear Medicine, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China); Li, Ying-Yi, E-mail: liyingyi@fudan.edu.cn [Cancer Research Institute, Fudan University Shanghai Cancer Center, Department of Oncology, Shanghai Medical College, Fudan University, Shanghai (China)

    2016-04-22

    Resistance of cancer cells to chemoradiotherapy is a major clinical problem in pancreatic cancer treatment. Therefore, understanding the molecular basis of cellular resistance and identifying novel targets are essential for improving treatment efficacy for pancreatic cancer patients. Previous studies have demonstrated a significant role for Pim-3 in pancreatic cancer survival against gemcitabine-induced genotoxic stress. Here, we observed that radiation treatment enhanced Pim-3 expression in human pancreatic cancer cells in vitro. Stable overexpression of Pim-3 in pancreatic cancer cells significantly protected cells against radiation treatment by attenuating G2/M phase cell cycle arrest and DNA damage response. Silencing of Pim-3 expression significantly elevated the phosphorylation of histone variant H2AX, a marker of DNA double strand breaks, and decreased the activation of ataxia-telangiectasia-mutated (ATM) kinase, along with its downstream targets, eventually enhancing the radiosensitivity of human pancreatic cancer cells in vitro and in vivo. Hence, we demonstrated a novel function for Pim-3 in human pancreatic cancer cell survival against radiation. Targeting Pim-3 may be a promising way to improve treatment efficacy in combination with radiotherapy in human pancreatic cancer. - Highlights: • This is first study to demonstrate that Pim-3 is endogenously induced by ionizing radiation in pancreatic cancer cells, and Pim-3 overexpression enhanced radioresistance of pancreatic cancer cells both in vitro and in vivo. • This is first study to provide evidence that radioresistance induced by Pim-3 is mainly attributed to Pim-3 induces activation of ATM, which subsequently activates checkpoint 1, leading to amplification of DNA repair through cell cycle arrest and DNA repair pathways. • This is first study to indicate that targeting Pim-3 may be a promising strategy to provide better treatment efficacy in combination with radiotherapy in human pancreatic

  18. Association between polymorphisms in the aryl hydrocarbon receptor repressor gene and disseminated testicular germ cell cancer

    Directory of Open Access Journals (Sweden)

    Leon J. S. Brokken

    2013-02-01

    Full Text Available In the Western world, testicular germ cell cancer (TGCC is the most common malignancy of young men. The malignant transformation of germ cells is thought to be caused by developmental and hormonal disturbances, probably related to environmental and lifestyle factors because of rapidly increasing incidence of TGCC in some countries. Additionally, there is a strong genetic component that affects susceptibility. However, genetic polymorphisms that have been identified so far only partially explain the risk of TGCC. Many of the persistent environmental pollutants act through the aryl hydrocarbon receptor (AHR. AHR signalling pathway is known to interfere with reproductive hormone signalling, which is supposed to play a role in the pathogenesis and invasive progression of TGCC. The aim of the present study was to identify whether AHR-related polymorphisms were associated with risk as well as histological and clinical features of TGCC in 367 patients and 537 controls. Haplotype-tagging single nucleotide polymorphisms (SNPs were genotyped in genes encoding AHR and AHR repressor (AHRR. Binary logistic regression was used to calculate the risk of TGCC, nonseminoma versus seminoma, and metastasis versus localised disease.Four SNPs in AHRR demonstrated a significant allele association with risk to develop metastases (rs2466287: OR = 0.43, 95% CI 0.21-0.90; rs2672725: OR = 0.49, 95% CI: 0.25-0.94; rs6879758: OR = 0.27, 95% CI: 0.08-0.92; rs6896163: OR = 0.34, 95% CI: 0.12-0.98.This finding supports the hypothesis that compounds acting through AHR may play a role in the invasive progression of TGCC, either directly or through modification of reproductive hormone action.

  19. Aryl hydrocarbon receptors in osteoclast lineage cells are a negative regulator of bone mass.

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    Tai-yong Yu

    Full Text Available Aryl hydrocarbon receptors (AhRs play a critical role in various pathological and physiological processes. Although recent research has identified AhRs as a key contributor to bone metabolism following studies in systemic AhR knockout (KO or transgenic mice, the cellular and molecular mechanism(s in this process remain unclear. In this study, we explored the function of AhR in bone metabolism using AhR(RANKΔOc/ΔOc (RANK(Cre/+;AhR(flox/flox mice. We observed enhanced bone mass together with decreased resorption in both male and female 12 and 24-week-old AhR(RANKΔOc/ΔOc mice. Control mice treated with 3-methylcholanthrene (3MC, an AhR agonist, exhibited decreased bone mass and increased bone resorption, whereas AhR(CtskΔOc/ΔOc (Ctsk(Cre/+;AhR(flox/flox mice injected with 3MC appeared to have a normal bone phenotype. In vitro, bone marrow-derived macrophages (BMDMs from AhR(RANKΔOc/ΔOc mice exhibited impaired osteoclastogenesis and repressed differentiation with downregulated expression of B lymphocyte-induced maturation protein 1 (Blimp1, and cytochrome P450 genes Cyp1b1 and Cyp1a2. Collectively, our results not only demonstrated that AhR in osteoclast lineage cells is a physiologically relevant regulator of bone resorption, but also highlighted the need for further studies on the skeletal actions of AhR inhibitors in osteoclast lineage cells commonly associated with bone diseases, especially diseases linked to environmental pollutants known to induce bone loss.

  20. Survival and SOS response induction in ultraviolet B irradiated Escherichia coli cells with defective repair mechanisms.

    Science.gov (United States)

    Prada Medina, Cesar Augusto; Aristizabal Tessmer, Elke Tatjana; Quintero Ruiz, Nathalia; Serment-Guerrero, Jorge; Fuentes, Jorge Luis

    2016-06-01

    Purpose In this paper, the contribution of different genes involved in DNA repair for both survival and SOS induction in Escherichia coli mutants exposed to ultraviolet B radiation (UVB, [wavelength range 280-315 nm]) was evaluated. Materials and methods E. coli strains defective in uvrA, oxyR, recO, recN, recJ, exoX, recB, recD or xonA genes were used to determine cell survival. All strains also had the genetic sulA::lacZ fusion, which allowed for the quantification of SOS induction through the SOS Chromotest. Results Five gene products were particularly important for survival, as follows: UvrA > RecB > RecO > RecJ > XonA. Strains defective in uvrA and recJ genes showed elevated SOS induction compared with the wild type, which remained stable for up to 240 min after UVB-irradiation. In addition, E. coli strains carrying the recO or recN mutation showed no SOS induction. Conclusions The nucleotide excision and DNA recombination pathways were equally used to repair UVB-induced DNA damage in E. coli cells. The sulA gene was not turned off in strains defective in UvrA and RecJ. RecO protein was essential for processing DNA damage prior to SOS induction. In this study, the roles of DNA repair proteins and their contributions to the mechanisms that induce SOS genes in E. coli are proposed.

  1. DNA damage repair is unaffected by mimicked heterozygous levels of BRCA2 in HT-29 cells

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    Brian Tannenbaum, Tobechukwu Mofunanya, Alan R. Schoenfeld

    2007-01-01

    Full Text Available Functional loss of both alleles of the breast cancer susceptibility gene, BRCA2, facilitates tumorigenesis. However, the direct effects of BRCA2 heterozygosity remain unclear. Here, BRCA2 heterozygosity was mimicked in HT-29 colon cells by reducing levels of BRCA2 through stable RNA interference. No difference in RAD51 subcellular localization and focus formation was observed between control and mimicked heterozygous cell lines. DNA repair ability, as measured by colony survival following mitomycin C treatment and ultraviolet radiation exposure, was also unaffected by reduced levels of BRCA2. Interestingly, the growth rate of the mimicked BRCA2 heterozygous cell line was significantly lower than that of control cells. Increased expression of p53 in the mimicked heterozygous cells was observed, perhaps in response to BRCA2 deficiency. Levels of p27 were also found to be slightly increased in cells with reduced BRCA2, perhaps contributing to the slower growth rate. Overall, these results suggest that tumors are unlikely to arise directly from BRCA2 heterozygous cells without other genetic events such as loss of the wild-type BRCA2 allele and/or loss of p53 function or other cell cycle inhibitors.

  2. Aging and photo-aging DNA repair phenotype of skin cells-Evidence toward an effect of chronic sun-exposure

    Energy Technology Data Exchange (ETDEWEB)

    Prunier, Chloe; Masson-Genteuil, Gwenaeelle [Laboratoire Lesions des Acides Nucleiques, CEA, DSM, INAC, SCIB, UMR-E CEA/UJF-Grenoble 1, 17 Rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Ugolin, Nicolas [Laboratoire de Cancerologie Experimentale, CEA, DSV, IRCM, SREIT, BP6, Fontenay-aux-Roses Cedex F-92265 (France); Sarrazy, Fanny [Laboratoire Lesions des Acides Nucleiques, CEA, DSM, INAC, SCIB, UMR-E CEA/UJF-Grenoble 1, 17 Rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Sauvaigo, Sylvie, E-mail: sylvie.sauvaigo@cea.fr [Laboratoire Lesions des Acides Nucleiques, CEA, DSM, INAC, SCIB, UMR-E CEA/UJF-Grenoble 1, 17 Rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

    2012-08-01

    Several studies have demonstrated the deleterious effect of aging on the capacity of cells to repair their DNA. However, current existing assays aimed at measuring DNA repair address only a specific repair step dedicated to the correction of a specific DNA lesion type. Consequently they provide no information regarding the repair pathways that handle other types of lesions. In addition to aging, consequences of photo-exposure on these repair processes remain elusive. In this study we evaluated the consequence of aging and of chronic and/or acute photo-exposure on DNA repair in human skin fibroblasts using a multiplexed approach, which provided detailed information on several repair pathways at the same time. The resulting data were analyzed with adapted statistics/bioinformatics tools. We showed that, irrespective of the repair pathway considered, excision/synthesis was less efficient in non-exposed cells from elderly compared to cells from young adults and that photo-exposure disrupted this very clear pattern. Moreover, it was evidenced that chronic sun-exposure induced changes in DNA repair properties. Finally, the identification of a specific signature at the level of the NER pathway in cells repeatedly exposed to sun revealed a cumulative effect of UVB exposure and chronic sun irradiation. The uses of bioinformatics tools in this study was essential to fully take advantage of the large sum of data obtained with our multiplexed DNA repair assay and unravel the effects of environmental exposure on DNA repair pathways.

  3. Cell cycle phase dependent role of DNA polymerase beta in DNA repair and survival after ionizing radiation.

    NARCIS (Netherlands)

    Vermeulen, C.; Verwijs-Janssen, M.; Begg, A.C.; Vens, C.

    2008-01-01

    PURPOSE: The purpose of the present study was to determine the role of DNA polymerase beta in repair and response after ionizing radiation in different phases of the cell cycle. METHODS AND MATERIALS: Synchronized cells deficient and proficient in DNA polymerase beta were irradiated in different pha

  4. The effect of a DNA repair gene on cellular invasiveness: XRCC3 over-expression in breast cancer cells.

    Directory of Open Access Journals (Sweden)

    Veronica L Martinez-Marignac

    Full Text Available Over-expression of DNA repair genes has been associated with resistance to radiation and DNA-damage induced by chemotherapeutic agents such as cisplatin. More recently, based on the analysis of genome expression profiling, it was proposed that over-expression of DNA repair genes enhances the invasive behaviour of tumour cells. In this study we present experimental evidence utilizing functional assays to test this hypothesis. We assessed the effect of the DNA repair proteins known as X-ray complementing protein 3 (XRCC3 and RAD51, to the invasive behavior of the MCF-7 luminal epithelial-like and BT20 basal-like triple negative human breast cancer cell lines. We report that stable or transient over-expression of XRCC3 but not RAD51 increased invasiveness in both cell lines in vitro. Moreover, XRCC3 over-expressing MCF-7 cells also showed a higher tumorigenesis in vivo and this phenotype was associated with increased activity of the metalloproteinase MMP-9 and the expression of known modulators of cell-cell adhesion and metastasis such as CD44, ID-1, DDR1 and TFF1. Our results suggest that in addition to its' role in facilitating repair of DNA damage, XRCC3 affects invasiveness of breast cancer cell lines and the expression of genes associated with cell adhesion and invasion.

  5. REPAIR OF LARGE SKULL BASE DEFECT FOLLOWING EXCISION OF BASALOID SQUAMOUS CELL CARCINOMA OF MAXILLO - ETHMOID REGION : A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Monoj Mukherjee

    2015-02-01

    Full Text Available AIM: To present a case of basaloid squamous cell carcinoma of maxillo - ethmoid region with intracranial extradural extention and its surgical management including repair of the skull base defect. MATERIAL : A 30 year female presented with progressive bilateral nasal obstruction, facial deformity for 5 years duration. She developed blindness in last 6 months. Recent CT s can showed large heterogeneous enhancing soft tissue mass in right maxillary sinus, nasal cavity and right ethmoid sinus invading the skull base . INTERVENTION : She underwent excision of the mass by modified weber ferguson incision and repair of skull base defect with temporalis muscle flap. Skin defect over the face and nose was repaired by median forehead flap. RESULT : There was total tumor clearance and no CSF leakage following surgery. CONCLUSION : Sinonasal malignancy with intracranial extradural extenti on is not a contraindication for successful surgical management. Resultant skull base defect can be repaired by a temporalis muscle flap to prevent CSF leak and intracranial infection

  6. Immunopharmacological intervention for successful neural stem cell therapy: New perspectives in CNS neurogenesis and repair.

    Science.gov (United States)

    Dooley, Dearbhaile; Vidal, Pia; Hendrix, Sven

    2014-01-01

    The pharmacological support and stimulation of endogenous and transplanted neural stem cells (NSCs) is a major challenge in brain repair. Trauma to the central nervous system (CNS) results in a distinct inflammatory response caused by local and infiltrating immune cells. This makes NSC-supported regeneration difficult due to the presence of inhibitory immune factors which are upregulated around the lesion site. The continual and dual role of the neuroinflammatory response leaves it difficult to decipher upon a single modulatory strategy. Therefore, understanding the influence of cytokines upon regulation of NSC self-renewal, proliferation and differentiation is crucial when designing therapies for CNS repair. There is a plethora of partially conflicting data in vitro and in vivo on the role of cytokines in modulating the stem cell niche and the milieu around NSC transplants. This is mainly due to the pleiotropic role of many factors. In order for cell-based therapy to thrive, treatment must be phase-specific to the injury and also be personalized for each patient, i.e. taking age, sex, neuroimmune and endocrine status as well as other key parameters into consideration. In this review, we will summarize the most relevant information concerning interleukin (IL)-1, IL-4, IL-10, IL-15, IFN-γ, the neuropoietic cytokine family and TNF-α in order to extract promising therapeutic approaches for further research. We will focus on the consequences of neuroinflammation on endogenous brain stem cells and the transplantation environment, the effects of the above cytokines on NSCs, as well as immunopharmacological manipulation of the microenvironment for potential therapeutic use.

  7. Peripheral Blood Mononuclear Cells Enhance Cartilage Repair in in vivo Osteochondral Defect Model.

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    Niina Hopper

    Full Text Available This study characterized peripheral blood mononuclear cells (PBMC in terms of their potential in cartilage repair and investigated their ability to improve the healing in a pre-clinical large animal model. Human PBMCs were isolated with gradient centrifugation and adherent PBMC's were evaluated for their ability to differentiate into adipogenic, chondrogenic and osteogenic lineages and also for their expression of musculoskeletal genes. The phenotype of the PBMCs was evaluated using Stro-1, CD34, CD44, CD45, CD90, CD106, CD105, CD146 and CD166 cell surface markers. Osteochondral defects were created in the medial femoral condyle (MFC of 24 Welsh mountain sheep and evaluated at a six month time point. Four cell treatment groups were evaluated in combination with collagen-GAG-scaffold: (1 MSC alone; (2 MSCs and PBMCs at a ratio of 20:1; (3 MSCs and PBMC at a ratio of 2:1 and (4 PBMCs alone. Samples from the surgical site were evaluated for mechanical properties, ICRS score and histological repair. Fresh PBMC samples were 90% positive for hematopoietic cell surface markers and negative for the MSC antibody panel (<1%, p = 0.006. However, the adherent PBMC population expressed mesenchymal stem cell markers in hypoxic culture and lacked CD34/45 positive cells (<0.2%. This finding demonstrated that the adherent cells had acquired an MSC-like phenotype and transformed in hypoxia from their original hematopoietic lineage. Four key genes in muskuloskeletal biology were significantly upregulated in adherent PBMCs by hypoxia: BMP2 4.2-fold (p = 0.0007, BMP6 10.7-fold (p = 0.0004, GDF5 2.0-fold (p = 0.002 and COL1 5.0-fold (p = 0.046. The monolayer multilineage analysis confirmed the trilineage mesenchymal potential of the adherent PBMCs. PBMC cell therapy was equally good as bone marrow MSC therapy for defects in the ovine large animal model. Our results show that PBMCs support cartilage healing and oxygen tension of the environment was found to have a key

  8. Tousled kinase activator, gallic acid, promotes homologous recombinational repair and suppresses radiation cytotoxicity in salivary gland cells.

    Science.gov (United States)

    Timiri Shanmugam, Prakash Srinivasan; Nair, Renjith Parameshwaran; De Benedetti, Arrigo; Caldito, Gloria; Abreo, Fleurette; Sunavala-Dossabhoy, Gulshan

    2016-04-01

    Accidental or medical radiation exposure of the salivary glands can gravely impact oral health. Previous studies have shown the importance of Tousled-like kinase 1 (TLK1) and its alternate start variant TLK1B in cell survival against genotoxic stresses. Through a high-throughput library screening of natural compounds, the phenolic phytochemical, gallic acid (GA), was identified as a modulator of TLK1/1B. This small molecule possesses anti-oxidant and free radical scavenging properties, but in this study, we report that in vitro it promotes survival of human salivary acinar cells, NS-SV-AC, through repair of ionizing radiation damage. Irradiated cells treated with GA show improved clonogenic survival compared to untreated controls. And, analyses of DNA repair kinetics by alkaline single-cell gel electrophoresis and γ-H2AX foci immunofluorescence indicate rapid resolution of DNA breaks in drug-treated cells. Study of DR-GFP transgene repair indicates GA facilitates homologous recombinational repair to establish a functional GFP gene. In contrast, inactivation of TLK1 or its shRNA knockdown suppressed resolution of radiation-induced DNA tails in NS-SV-AC, and homology directed repair in DR-GFP cells. Consistent with our results in culture, animals treated with GA after exposure to fractionated radiation showed better preservation of salivary function compared to saline-treated animals. Our results suggest that GA-mediated transient modulation of TLK1 activity promotes DNA repair and suppresses radiation cytoxicity in salivary gland cells.

  9. Moving stem cells to the clinic: potential and limitations for brain repair.

    Science.gov (United States)

    Steinbeck, Julius A; Studer, Lorenz

    2015-04-08

    Stem cell-based therapies hold considerable promise for many currently devastating neurological disorders. Substantial progress has been made in the derivation of disease-relevant human donor cell populations. Behavioral data in relevant animal models of disease have demonstrated therapeutic efficacy for several cell-based approaches. Consequently, cGMP grade cell products are currently being developed for first in human clinical trials in select disorders. Despite the therapeutic promise, the presumed mechanism of action of donor cell populations often remains insufficiently validated. It depends greatly on the properties of the transplanted cell type and the underlying host pathology. Several new technologies have become available to probe mechanisms of action in real time and to manipulate in vivo cell function and integration to enhance therapeutic efficacy. Results from such studies generate crucial insight into the nature of brain repair that can be achieved today and push the boundaries of what may be possible in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Myelin repair and functional recovery mediated by neural cell transplantation in a mouse model of multiple sclerosis

    Institute of Scientific and Technical Information of China (English)

    Lianhua Bai; Jordan Hecker; Amber Kerstetter; Robert H.Miller

    2013-01-01

    Cellular therapies are becoming a major focus for the treatment of demyelinating diseases such as multiple sclerosis (MS),therefore it is important to identify the most effective cell types that promote myelin repair.Several components contribute to the relative benefits of specific cell types including the overall efficacy of the cell therapy,the reproducibility of treatment,the mechanisms of action of distinct cell types and the ease of isolation and generation of therapeutic populations.A range of distinct cell populations promote functional recovery in animal models of MS including neural stem cells and mesenchymal stem cells derived from different tissues.Each of these cell populations has advantages and disadvantages and likely works through distinct mechanisms.The relevance of such mechanisms to myelin repair in the adult central nervous system is unclear since the therapeutic cells are generally derived from developing animals.Here we describe the isolation and characterization of a population of neural cells from the adult spinal cord that are characterized by the expression of the cell surface glycoprotein NG2.In functional studies,injection of adult NG2+ cells into mice with ongoing MOG35-55-induced experimental autoimmune encephalomyelitis (EAE) enhanced remyelination in the CNS while the number of CD3+ T cells in areas of spinal cord demyelination was reduced approximately three-fold.In vivo studies indicated that in EAE,NG2+ cells stimulated endogenous repair while in vitro they responded to signals in areas of induced inflammation by differentiating into oligodendrocytes.These results suggested that adult NG2+ cells represent a useful cell population for promoting neural repair in a variety of different conditions including demyelinating diseases such as MS.

  11. Assessing adsorption of polycyclic aromatic hydrocarbons on Rhizopus oryzae cell wall components with water-methanol cosolvent model.

    Science.gov (United States)

    Ma, Bin; Lv, Xiaofei; He, Yan; Xu, Jianming

    2016-03-01

    The contribution of different fungal cell wall components in adsorption of polycyclic aromatic hydrocarbons (PAHs) is still unclear. We isolated Rhizopus oryzae cell walls components with sequential extraction, characterized functional groups with NEXAFS spectra, and determined partition coefficients of PAHs on cell walls and cell wall components with cosolvent model. Spectra of NEXAFS indicated that isolated cell walls components were featured with peaks at ~532.7 and ~534.5eV energy. The lipid cosolvent partition coefficients were approximately one order of magnitude higher than the corresponding carbohydrate cosolvent partition coefficients. The partition coefficients for four tested carbohydrates varied at approximate 0.5 logarithmic units. Partition coefficients between biosorbents and water calculated based cosolvent models ranged from 0.8 to 4.2. The present study proved the importance of fungal cell wall components in adsorption of PAHs, and consequently the role of fungi in PAHs bioremediation.

  12. Manipulation of cell cycle progression can counteract the apparent loss of correction frequency following oligonucleotide-directed gene repair

    Directory of Open Access Journals (Sweden)

    Kmiec Eric B

    2007-02-01

    Full Text Available Abstract Background Single-stranded oligonucleotides (ssODN are used routinely to direct specific base alterations within mammalian genomes that result in the restoration of a functional gene. Despite success with the technique, recent studies have revealed that following repair events, correction frequencies decrease as a function of time, possibly due to a sustained activation of damage response signals in corrected cells that lead to a selective stalling. In this study, we use thymidine to slow down the replication rate to enhance repair frequency and to maintain substantial levels of correction over time. Results First, we utilized thymidine to arrest cells in G1 and released the cells into S phase, at which point specific ssODNs direct the highest level of correction. Next, we devised a protocol in which cells are maintained in thymidine following the repair reaction, in which the replication is slowed in both corrected and non-corrected cells and the initial correction frequency is retained. We also present evidence that cells enter a senescence state upon prolonged treatment with thymidine but this passage can be avoided by removing thymidine at 48 hours. Conclusion Taken together, we believe that thymidine may be used in a therapeutic fashion to enable the maintenance of high levels of treated cells bearing repaired genes.

  13. Electrical Stimulation Elicit Neural Stem Cells Activation:New Perspectives in CNS Repair

    Directory of Open Access Journals (Sweden)

    Ratrel eHuang

    2015-10-01

    Full Text Available Researchers are enthusiastically concerned about neural stem cell (NSC therapy in a wide array of diseases, including stroke, neurodegenerative disease, spinal cord injury (SCI and depression. Although enormous evidences have demonstrated that neurobehavioral improvement may benefit from NSC-supporting regeneration in animal models, approaches to endogenous and transplanted NSCs are blocked by hurdles of migration, proliferation, maturation and integration of NSCs. Electrical stimulation (ES may be a selective nondrug approach for mobilizing NSCs in the central nervous system (CNS. This technique is suitable for clinic application, because it is well established and its potential complications are manageable. Here, we provide a comprehensive review of the emerging positive role of different electrical cues in regulating NSC biology in vitro and in vivo, as well as biomaterial-based and chemical stimulation of NSCs. In the future, ES combined with stem cell therapy or other cues probably becomes an approach for promoting brain repair.

  14. Neural crest stem cell population in craniomaxillofacial development and tissue repair

    Directory of Open Access Journals (Sweden)

    M La Noce

    2014-10-01

    Full Text Available Neural crest cells, delaminating from the neural tube during migration, undergo an epithelial-mesenchymal transition and differentiate into several cell types strongly reinforcing the mesoderm of the craniofacial body area – giving rise to bone, cartilage and other tissues and cells of this human body area. Recent studies on craniomaxillofacial neural crest-derived cells have provided evidence for the tremendous plasticity of these cells. Actually, neural crest cells can respond and adapt to the environment in which they migrate and the cranial mesoderm plays an important role toward patterning the identity of the migrating neural crest cells. In our experience, neural crest-derived stem cells, such as dental pulp stem cells, can actively proliferate, repair bone and give rise to other tissues and cytotypes, including blood vessels, smooth muscle, adipocytes and melanocytes, highlighting that their use in tissue engineering is successful. In this review, we provide an overview of the main pathways involved in neural crest formation, delamination, migration and differentiation; and, in particular, we concentrate our attention on the translatability of the latest scientific progress. Here we try to suggest new ideas and strategies that are needed to fully develop the clinical use of these cells. This effort should involve both researchers/clinicians and improvements in good manufacturing practice procedures. It is important to address studies towards clinical application or take into consideration that studies must have an effective therapeutic prospect for humans. New approaches and ideas must be concentrated also toward stem cell recruitment and activation within the human body, overcoming the classical grafting.

  15. Regulation of estrogen sulfotransferase expression by confluence of MCF10A breast epithelial cells: role of the aryl hydrocarbon receptor.

    Science.gov (United States)

    Fu, Jiaqi; Fang, Hailin; Paulsen, Michelle; Ljungman, Mats; Kocarek, Thomas A; Runge-Morris, Melissa

    2011-11-01

    Estrogen sulfotransferase (SULT1E1) catalyzes the sulfonation of estrogens, which limits estrogen mitogenicity. We recently reported that SULT1E1 expression is low in preconfluent MCF10A human breast epithelial cells but increases when the cells become confluent. Pulse-chase labeling experiments with 5-bromouridine demonstrated that the confluence-mediated increase in SULT1E1 expression was due to increased mRNA synthesis. Because aryl hydrocarbon receptor (AhR) activation has been shown to suppress SULT1E1 expression and loss of cell-cell contact has been shown to activate the AhR in other cell types, we tested whether the confluence-associated changes in SULT1E1 expression were mediated by the AhR. Relative to confluent MCF10A cells, preconfluent cells had higher levels of CYP1A1 mRNA and greater activation of an AhR-responsive luciferase reporter, demonstrating that the AhR was active in the preconfluent cells. AhR and aryl hydrocarbon receptor nuclear translocator mRNA and protein levels were also higher in preconfluent than in confluent cultures. Treatment of preconfluent cells with the AhR antagonist, 3'-methoxy-4'-nitroflavone (MNF), or AhR knockdown significantly increased SULT1E1 expression. MCF10A cells stably transfected with a luciferase reporter containing ∼7 kilobases of the SULT1E1 5'-flanking region showed both MNF- and confluence-inducible luciferase expression. Preconfluent cells transiently transfected with the reporter showed both MNF treatment- and AhR knockdown-mediated luciferase induction, but mutation of a computationally predicted dioxin response element (DRE) at nucleotide (nt) -3476 did not attenuate these effects. These results demonstrate that SULT1E1 expression in MCF10A cells is transcriptionally regulated by confluence through a suppressive action of the AhR, which is not mediated through a DRE at nt -3476.

  16. The Fanconi anemia pathway: Repairing the link between DNA damage and squamous cell carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Romick-Rosendale, Lindsey E. [Division of Oncology, Cancer and Blood Diseases Institute, Cincinnati Children' s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229 (United States); Lui, Vivian W.Y.; Grandis, Jennifer R. [Department of Otolaryngology, University of Pittsburgh School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213 (United States); Wells, Susanne I., E-mail: Susanne.Wells@cchmc.org [Division of Oncology, Cancer and Blood Diseases Institute, Cincinnati Children' s Hospital Medical Center, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45229 (United States)

    2013-03-15

    Fanconi anemia (FA) is a rare inherited recessive disease caused by mutations in one of fifteen genes known to encode FA pathway components. In response to DNA damage, nuclear FA proteins associate into high molecular weight complexes through a cascade of post-translational modifications and physical interactions, followed by the repair of damaged DNA. Hematopoietic cells are particularly sensitive to the loss of these interactions, and bone marrow failure occurs almost universally in FA patients. FA as a disease is further characterized by cancer susceptibility, which highlights the importance of the FA pathway in tumor suppression, and will be the focus of this review. Acute myeloid leukemia is the most common cancer type, often subsequent to bone marrow failure. However, FA patients are also at an extreme risk of squamous cell carcinoma (SCC) of the head and neck and gynecological tract, with an even greater incidence in those individuals who have received a bone marrow transplant and recovered from hematopoietic disease. FA tumor suppression in hematopoietic versus epithelial compartments could be mechanistically similar or distinct. Definition of compartment specific FA activities is now critical to assess the effects of today's bone marrow failure treatments on tomorrow's solid tumor development. It is our hope that current therapies can then be optimized to decrease the risk of malignant transformation in both hematopoietic and epithelial cells. Here we review our current understanding of the mechanisms of action of the Fanconi anemia pathway as it contributes to stress responses, DNA repair and squamous cell carcinoma susceptibility.

  17. DSB repair model for mammalian cells in early S and G1 phases of the cell cycle: application to damage induced by ionizing radiation of different quality.

    Science.gov (United States)

    Taleei, Reza; Girard, Peter M; Nikjoo, Hooshang

    2015-02-01

    The purpose of this work is to test the hypothesis that kinetics of double strand breaks (DSB) repair is governed by complexity of DSB. To test the hypothesis we used our recent published mechanistic mathematical model of DSB repair for DSB induced by selected protons, deuterons, and helium ions of different energies representing radiations of different qualities. In light of recent advances in experimental and computational techniques, the most appropriate method to study cellular responses in radiation therapy, and exposures to low doses of ionizing radiations is using mechanistic approaches. To this end, we proposed a 'bottom-up' approach to study cellular response that starts with the DNA damage. Monte Carlo track structure method was employed to simulate initial damage induced in the genomic DNA by direct and indirect effects. Among the different types of DNA damage, DSB are known to be induced in simple and complex forms. The DSB repair model in G1 and early S phases of the cell cycle was employed to calculate the repair kinetics. The model considers the repair of simple and complex DSB, and the DSB produced in the heterochromatin. The inverse sampling method was used to calculate the repair kinetics for each individual DSB. The overall repair kinetics for 500 DSB induced by single tracks of the radiation under test were compared with experimental results. The results show that the model is capable of predicting the repair kinetics for the DSB induced by radiations of different qualities within an accepted range of uncertainty.

  18. Loss of DNA mismatch repair imparts a selective advantage in planarian adult stem cells.

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    Jessica P Hollenbach

    Full Text Available Lynch syndrome (LS leads to an increased risk of early-onset colorectal and other types of cancer and is caused by germline mutations in DNA mismatch repair (MMR genes. Loss of MMR function results in a mutator phenotype that likely underlies its role in tumorigenesis. However, loss of MMR also results in the elimination of a DNA damage-induced checkpoint/apoptosis activation barrier that may allow damaged cells to grow unchecked. A fundamental question is whether loss of MMR provides pre-cancerous stem cells an immediate selective advantage in addition to establishing a mutator phenotype. To test this hypothesis in an in vivo system, we utilized the planarian Schmidtea mediterranea which contains a significant population of identifiable adult stem cells. We identified a planarian homolog of human MSH2, a MMR gene which is mutated in 38% of LS cases. The planarian Smed-msh2 is expressed in stem cells and some progeny. We depleted Smed-msh2 mRNA levels by RNA-interference and found a striking survival advantage in these animals treated with a cytotoxic DNA alkylating agent compared to control animals. We demonstrated that this tolerance to DNA damage is due to the survival of mitotically active, MMR-deficient stem cells. Our results suggest that loss of MMR provides an in vivo survival advantage to the stem cell population in the presence of DNA damage that may have implications for tumorigenesis.

  19. Loss of DNA mismatch repair imparts a selective advantage in planarian adult stem cells.

    Science.gov (United States)

    Hollenbach, Jessica P; Resch, Alissa M; Palakodeti, Dasaradhi; Graveley, Brenton R; Heinen, Christopher D

    2011-01-01

    Lynch syndrome (LS) leads to an increased risk of early-onset colorectal and other types of cancer and is caused by germline mutations in DNA mismatch repair (MMR) genes. Loss of MMR function results in a mutator phenotype that likely underlies its role in tumorigenesis. However, loss of MMR also results in the elimination of a DNA damage-induced checkpoint/apoptosis activation barrier that may allow damaged cells to grow unchecked. A fundamental question is whether loss of MMR provides pre-cancerous stem cells an immediate selective advantage in addition to establishing a mutator phenotype. To test this hypothesis in an in vivo system, we utilized the planarian Schmidtea mediterranea which contains a significant population of identifiable adult stem cells. We identified a planarian homolog of human MSH2, a MMR gene which is mutated in 38% of LS cases. The planarian Smed-msh2 is expressed in stem cells and some progeny. We depleted Smed-msh2 mRNA levels by RNA-interference and found a striking survival advantage in these animals treated with a cytotoxic DNA alkylating agent compared to control animals. We demonstrated that this tolerance to DNA damage is due to the survival of mitotically active, MMR-deficient stem cells. Our results suggest that loss of MMR provides an in vivo survival advantage to the stem cell population in the presence of DNA damage that may have implications for tumorigenesis.

  20. DNA Repair Cofactors ATMIN and NBS1 Are Required to Suppress T Cell Activation.

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    Jana Prochazkova

    2015-11-01

    Full Text Available Proper development of the immune system is an intricate process dependent on many factors, including an intact DNA damage response. The DNA double-strand break signaling kinase ATM and its cofactor NBS1 are required during T cell development and for the maintenance of genomic stability. The role of a second ATM cofactor, ATMIN (also known as ASCIZ in T cells is much less clear, and whether ATMIN and NBS1 function in synergy in T cells is unknown. Here, we investigate the roles of ATMIN and NBS1, either alone or in combination, using murine models. We show loss of NBS1 led to a developmental block at the double-positive stage of T cell development, as well as reduced TCRα recombination, that was unexpectedly neither exacerbated nor alleviated by concomitant loss of ATMIN. In contrast, loss of both ATMIN and NBS1 enhanced DNA damage that drove spontaneous peripheral T cell hyperactivation, proliferation as well as excessive production of proinflammatory cytokines and chemokines, leading to a highly inflammatory environment. Intriguingly, the disease causing T cells were largely proficient for both ATMIN and NBS1. In vivo this resulted in severe intestinal inflammation, colitis and premature death. Our findings reveal a novel model for an intestinal bowel disease phenotype that occurs upon combined loss of the DNA repair cofactors ATMIN and NBS1.

  1. DNA Repair Cofactors ATMIN and NBS1 Are Required to Suppress T Cell Activation.

    Science.gov (United States)

    Prochazkova, Jana; Sakaguchi, Shinya; Owusu, Michel; Mazouzi, Abdelghani; Wiedner, Marc; Velimezi, Georgia; Moder, Martin; Turchinovich, Gleb; Hladik, Anastasiya; Gurnhofer, Elisabeth; Hayday, Adrian; Behrens, Axel; Knapp, Sylvia; Kenner, Lukas; Ellmeier, Wilfried; Loizou, Joanna I

    2015-11-01

    Proper development of the immune system is an intricate process dependent on many factors, including an intact DNA damage response. The DNA double-strand break signaling kinase ATM and its cofactor NBS1 are required during T cell development and for the maintenance of genomic stability. The role of a second ATM cofactor, ATMIN (also known as ASCIZ) in T cells is much less clear, and whether ATMIN and NBS1 function in synergy in T cells is unknown. Here, we investigate the roles of ATMIN and NBS1, either alone or in combination, using murine models. We show loss of NBS1 led to a developmental block at the double-positive stage of T cell development, as well as reduced TCRα recombination, that was unexpectedly neither exacerbated nor alleviated by concomitant loss of ATMIN. In contrast, loss of both ATMIN and NBS1 enhanced DNA damage that drove spontaneous peripheral T cell hyperactivation, proliferation as well as excessive production of proinflammatory cytokines and chemokines, leading to a highly inflammatory environment. Intriguingly, the disease causing T cells were largely proficient for both ATMIN and NBS1. In vivo this resulted in severe intestinal inflammation, colitis and premature death. Our findings reveal a novel model for an intestinal bowel disease phenotype that occurs upon combined loss of the DNA repair cofactors ATMIN and NBS1.

  2. Paracrine Engineering of Human Explant-Derived Cardiac Stem Cells to Over-Express Stromal-Cell Derived Factor 1α Enhances Myocardial Repair.

    Science.gov (United States)

    Tilokee, Everad L; Latham, Nicholas; Jackson, Robyn; Mayfield, Audrey E; Ye, Bin; Mount, Seth; Lam, Buu-Khanh; Suuronen, Erik J; Ruel, Marc; Stewart, Duncan J; Davis, Darryl R

    2016-07-01

    First generation cardiac stem cell products provide indirect cardiac repair but variably produce key cardioprotective cytokines, such as stromal-cell derived factor 1α, which opens the prospect of maximizing up-front paracrine-mediated repair. The mesenchymal subpopulation within explant derived human cardiac stem cells underwent lentiviral mediated gene transfer of stromal-cell derived factor 1α. Unlike previous unsuccessful attempts to increase efficacy by boosting the paracrine signature of cardiac stem cells, cytokine profiling revealed that stromal-cell derived factor 1α over-expression prevented lv-mediated "loss of cytokines" through autocrine stimulation of CXCR4+ cardiac stem cells. Stromal-cell derived factor 1α enhanced angiogenesis and stem cell recruitment while priming cardiac stem cells to readily adopt a cardiac identity. As compared to injection with unmodified cardiac stem cells, transplant of stromal-cell derived factor 1α enhanced cells into immunodeficient mice improved myocardial function and angiogenesis while reducing scarring. Increases in myocardial stromal-cell derived factor 1α content paralleled reductions in myocyte apoptosis but did not influence long-term engraftment or the fate of transplanted cells. Transplantation of stromal-cell derived factor 1α transduced cardiac stem cells increased the generation of new myocytes, recruitment of bone marrow cells, new myocyte/vessel formation and the salvage of reversibly damaged myocardium to enhance cardiac repair after experimental infarction. Stem Cells 2016;34:1826-1835.

  3. Repair of osteochondral defects with in vitro engineered cartilage based on autologous bone marrow stromal cells in a swine model

    Science.gov (United States)

    He, Aijuan; Liu, Lina; Luo, Xusong; Liu, Yu; Liu, Yi; Liu, Fangjun; Wang, Xiaoyun; Zhang, Zhiyong; Zhang, Wenjie; Liu, Wei; Cao, Yilin; Zhou, Guangdong

    2017-01-01

    Functional reconstruction of large osteochondral defects is always a major challenge in articular surgery. Some studies have reported the feasibility of repairing articular osteochondral defects using bone marrow stromal cells (BMSCs) and biodegradable scaffolds. However, no significant breakthroughs have been achieved in clinical translation due to the instability of in vivo cartilage regeneration based on direct cell-scaffold construct implantation. To overcome the disadvantages of direct cell-scaffold construct implantation, the current study proposed an in vitro cartilage regeneration strategy, providing relatively mature cartilage-like tissue with superior mechanical properties. Our strategy involved in vitro cartilage engineering, repair of osteochondral defects, and evaluation of in vivo repair efficacy. The results demonstrated that BMSC engineered cartilage in vitro (BEC-vitro) presented a time-depended maturation process. The implantation of BEC-vitro alone could successfully realize tissue-specific repair of osteochondral defects with both cartilage and subchondral bone. Furthermore, the maturity level of BEC-vitro had significant influence on the repaired results. These results indicated that in vitro cartilage regeneration using BMSCs is a promising strategy for functional reconstruction of osteochondral defect, thus promoting the clinical translation of cartilage regeneration techniques incorporating BMSCs. PMID:28084417

  4. Lung Basal Stem Cells Rapidly Repair DNA Damage Using the Error-Prone Nonhomologous End-Joining Pathway.

    Science.gov (United States)

    Weeden, Clare E; Chen, Yunshun; Ma, Stephen B; Hu, Yifang; Ramm, Georg; Sutherland, Kate D; Smyth, Gordon K; Asselin-Labat, Marie-Liesse

    2017-01-01

    Lung squamous cell carcinoma (SqCC), the second most common subtype of lung cancer, is strongly associated with tobacco smoking and exhibits genomic instability. The cellular origins and molecular processes that contribute to SqCC formation are largely unexplored. Here we show that human basal stem cells (BSCs) isolated from heavy smokers proliferate extensively, whereas their alveolar progenitor cell counterparts have limited colony-forming capacity. We demonstrate that this difference arises in part because of the ability of BSCs to repair their DNA more efficiently than alveolar cells following ionizing radiation or chemical-induced DNA damage. Analysis of mice harbouring a mutation in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a key enzyme in DNA damage repair by nonhomologous end joining (NHEJ), indicated that BSCs preferentially repair their DNA by this error-prone process. Interestingly, polyploidy, a phenomenon associated with genetically unstable cells, was only observed in the human BSC subset. Expression signature analysis indicated that BSCs are the likely cells of origin of human SqCC and that high levels of NHEJ genes in SqCC are correlated with increasing genomic instability. Hence, our results favour a model in which heavy smoking promotes proliferation of BSCs, and their predilection for error-prone NHEJ could lead to the high mutagenic burden that culminates in SqCC. Targeting DNA repair processes may therefore have a role in the prevention and therapy of SqCC.

  5. Transplantation of erythropoietin gene-modified neural stem cells improves the repair of injured spinal cord

    Directory of Open Access Journals (Sweden)

    Min-fei Wu

    2015-01-01

    cells into the subarachnoid cavity to help repair spinal cord injury and promote the recovery of spinal cord function better than neural stem cell transplantation alone. These findings may lead to significant improvements in the clinical treatment of spinal cord injuries.

  6. Transplantation of erythropoietin gene-modified neural stem cells improves the repair of injured spinal cord.

    Science.gov (United States)

    Wu, Min-Fei; Zhang, Shu-Quan; Gu, Rui; Liu, Jia-Bei; Li, Ye; Zhu, Qing-San

    2015-09-01

    subarachnoid cavity to help repair spinal cord injury and promote the recovery of spinal cord function better than neural stem cell transplantation alone. These findings may lead to significant improvements in the clinical treatment of spinal cord injuries.

  7. Transplantation of erythropoietin gene-modiifed neural stem cells improves the repair of injured spinal cord

    Institute of Scientific and Technical Information of China (English)

    Min-fei Wu; Shu-quan Zhang; Rui Gu; Jia-bei Liu; Ye Li; Qing-san Zhu

    2015-01-01

    subarachnoid cavity to help repair spinal cord injury and promote the recovery of spinal cord function better than neural stem cell transplantation alone. These ifndings may lead to signiifcant improvements in the clinical treatment of spinal cord injuries.

  8. A cell-free system for studying a priming factor involved in repair of bleomycin-damaged DNA.

    Directory of Open Access Journals (Sweden)

    Seki,Shuji

    1989-04-01

    Full Text Available A simple cell-free system for studying a priming factor involved in the repair of bleomycin-damaged DNA was established. The template-primer used for the repair DNA synthesis was prepared by treating the closed circular, superhelical form of pUC19 plasmid DNA with 2.2 microM bleomycin and 20 microM ferrous ions. Single-strand breaks were introduced into pUC19 DNA by the bleomycin treatment, and the DNA was consequently converted largely into the open circular form. A system for repair of this bleomycin-damaged DNA was constructed with a priming factor, DNA polymerase (DNA polymerase beta or Klenow fragment of DNA polymerase I, ATP, T4 DNA ligase and four deoxynucleoside triphosphates. After incubation, the conformation of the DNA was analyzed by agarose gel electrophoresis and electron microscopy. The open circular DNA was largely converted to the closed circular DNA, indicating that the single-strand breaks of DNA were repaired. When the priming factor was omitted, DNA repair did not occur. The present system seemed to be applicable to the study of priming factors involved in the repair of DNA with single-strand breaks caused not only by bleomycin but also by ionizing radiation or active oxygen.

  9. Human induced pluripotent cells resemble embryonic stem cells demonstrating enhanced levels of DNA repair and efficacy of nonhomologous end-joining

    Energy Technology Data Exchange (ETDEWEB)

    Fan Jinshui; Robert, Carine [Department of Radiation Oncology, University of Maryland School of Medicine, 655 West Baltimore Street, BRB 7-023A, Baltimore, MD 21201 (United States); Jang, Yoon-Young; Liu Hua; Sharkis, Saul; Baylin, Stephen Bruce [Johns Hopkins University School of Medicine, Department of Oncology, Baltimore, MD 21231-1000 (United States); Rassool, Feyruz Virgilia, E-mail: frassool@som.umaryland.edu [Department of Radiation Oncology, University of Maryland School of Medicine, 655 West Baltimore Street, BRB 7-023A, Baltimore, MD 21201 (United States)

    2011-08-01

    Highlights: {yields} iPSC and hESC demonstrate a similar cell cycle profile, with increased S phase cells and decreased G0/G1. {yields} iPSC and hESC increased ROS and decreased DSBs, compared with differentiated parental cells. {yields} iPSC and hESC demonstrate elevated DSB repair activity, including nonhomologous end-joining, compared with differentiated parental cells. {yields} iPSC however show a partial apoptotic response to DNA damage, compared to hESC. {yields} DNA damage responses may constitute important markers for the efficacy of iPSC reprogramming. - Abstract: To maintain the integrity of the organism, embryonic stem cells (ESC) need to maintain their genomic integrity in response to DNA damage. DNA double strand breaks (DSBs) are one of the most lethal forms of DNA damage and can have disastrous consequences if not repaired correctly, leading to cell death, genomic instability and cancer. How human ESC (hESC) maintain genomic integrity in response to agents that cause DSBs is relatively unclear. Adult somatic cells can be induced to 'dedifferentiate' into induced pluripotent stem cells (iPSC) and reprogram into cells of all three germ layers. Whether iPSC have reprogrammed the DNA damage response is a critical question in regenerative medicine. Here, we show that hESC demonstrate high levels of endogenous reactive oxygen species (ROS) which can contribute to DNA damage and may arise from high levels of metabolic activity. To potentially counter genomic instability caused by DNA damage, we find that hESC employ two strategies: First, these cells have enhanced levels of DNA repair proteins, including those involved in repair of DSBs, and they demonstrate elevated nonhomologous end-joining (NHEJ) activity and repair efficacy, one of the main pathways for repairing DSBs. Second, they are hypersensitive to DNA damaging agents, as evidenced by a high level of apoptosis upon irradiation. Importantly, iPSC, unlike the parent cells they are derived

  10. Site-specific regulation of cell cycle and DNA repair in post-mitotic GABA cells in schizophrenic versus bipolars.

    Science.gov (United States)

    Benes, Francine M; Lim, Benjamin; Subburaju, Sivan

    2009-07-14

    GABA cell dysfunction in both schizophrenia (SZ) and bipolar disorder (BD) involves decreased GAD(67) expression, although this change involves fundamentally different networks of genes in the 2 disorders. One gene that is common to these 2 networks is cyclin D2, a key component of cell cycle regulation that shows increased expression in SZ, but decreased expression in BD. Because of the importance of cell cycle regulation in maintaining functional differentiation and DNA repair, the current study has examined the genes involved in the G(1) and G(2) checkpoints to generate new hypotheses regarding the regulation of the GABA cell phenotype in the hippocampus of SZ and BD. The results have demonstrated significant changes in cell cycle regulation in both SZ and BD and these changes include the transcriptional complex (TC) that controls the expression of E2F/DP-1 target genes critical for progression to G(2)/M. The methyl-CpG binding domain protein (MBD4) that is pivotal for DNA repair, is significantly up-regulated in the stratum oriens (SO) of CA3/2 and CA1 in SZs and BDs. However, other genes associated with the TC, and the G(1) and G(2) checkpoints, show complex changes in expression in the SO of CA3/2 and CA1 of both SZs and BDS. Overall, the patterns of expression observed have suggested that the regulation of functional differentiation and/or genomic integrity of hippocampal GABA cells varies according to diagnosis and their location within the trisynaptic pathway.

  11. Efficacy of Schwann cell transplantation for spinal cord repair is improved with combinatorial strategies.

    Science.gov (United States)

    Bunge, Mary Bartlett

    2016-07-01

    When cells (including Schwann cells; SCs) of the peripheral nervous system (PNS) could be purified and expanded in number in tissue culture, Richard Bunge in 1975 envisioned that the SCs could be introduced to repair the central nervous system (CNS), as SCs enable axons to regenerate after PNS injury. Importantly, autologous human SCs could be transplanted into injured human spinal cord. Availability of the new culture systems to study interactions between sensory neurons, SCs and fibroblasts increased our knowledge of SC biology in the 1970s and '80s. Joining the Miami Project to Cure Paralysis in 1989 brought the opportunity to use this knowledge to initiate spinal cord repair studies. Development of a rat complete spinal cord transection/SC bridge model allowed the demonstration that axons regenerate into the SC bridge. Together with study of contused rat spinal cord, it was concluded that implanted SCs reduce cavitation, protect tissue around the lesion, support axon regeneration and form myelin. SC transplantation efficacy was improved when combined with neurotrophins, elevation of cyclic AMP levels, olfactory ensheathing cells, a steroid or chondroitinase. Increased efficacy meant higher numbers of axons, particularly from the brainstem, and more SC-myelinated axons in the implants and improvement in hindlimb movements. Human SCs support axon regeneration as do rat SCs. Astrocytes at the SC bridge-host spinal cord interfaces play a key role in determining whether axons enter the SC milieu. The SC work described here contributed to gaining approval from the FDA for an initial autologous human SC clinical trial (at the Miami Project) that has been completed and found to be safe.

  12. The sulfated polysaccharide fucoidan rescues senescence of endothelial colony-forming cells for ischemic repair.

    Science.gov (United States)

    Lee, Jun Hee; Lee, Sang Hun; Choi, Sung Hyun; Asahara, Takayuki; Kwon, Sang-Mo

    2015-06-01

    The efficacy of cell therapy using endothelial colony-forming cells (ECFCs) in the treatment of ischemia is limited by the replicative senescence of isolated ECFCs in vitro. Such senescence must therefore be overcome in order for such cell therapies to be clinically applicable. This study aimed to investigate the potential of sulfated polysaccharide fucoidan to rescue ECFCs from cellular senescence and to improve in vivo vascular repair by ECFCs. Fucoidan-preconditioning of senescent ECFCs was shown by flow cytometry to restore the expression of functional ECFC surface markers (CD34, c-Kit, VEGFR2, and CXCR4) and stimulate the in vitro tube formation capacity of ECFCs. Fucoidan also promoted the expression of cell cycle-associated proteins (cyclin E, Cdk2, cyclin D1, and Cdk4) in senescent ECFCs, significantly reversed cellular senescence, and increased the proliferation of ECFCs via the FAK, Akt, and ERK signaling pathways. Fucoidan was found to enhance the survival, proliferation, incorporation, and endothelial differentiation of senescent ECFCs transplanted in ischemic tissues in a murine hind limb ischemia model. Moreover, ECFC-induced functional recovery and limb salvage were markedly improved by fucoidan pretreatment of ECFCs. To our knowledge, the findings of our study are the first to demonstrate that fucoidan enhances the neovasculogenic potential of ECFCs by rescuing them from replicative cellular senescence. Pretreatment of ECFCs with fucoidan may thus provide a novel strategy for the application of senescent stem cells to therapeutic neovascularization.

  13. Human umbilical cord mesenchymal stem cells promote peripheral nerve repair via paracrine mechanisms

    Directory of Open Access Journals (Sweden)

    Zhi-yuan Guo

    2015-01-01

    Full Text Available Human umbilical cord-derived mesenchymal stem cells (hUCMSCs represent a promising young-state stem cell source for cell-based therapy. hUCMSC transplantation into the transected sciatic nerve promotes axonal regeneration and functional recovery. To further clarify the paracrine effects of hUCMSCs on nerve regeneration, we performed human cytokine antibody array analysis, which revealed that hUCMSCs express 14 important neurotrophic factors. Enzyme-linked immunosorbent assay and immunohistochemistry showed that brain-derived neurotrophic factor, glial-derived neurotrophic factor, hepatocyte growth factor, neurotrophin-3, basic fibroblast growth factor, type I collagen, fibronectin and laminin were highly expressed. Treatment with hUCMSC-conditioned medium enhanced Schwann cell viability and proliferation, increased nerve growth factor and brain-derived neurotrophic factor expression in Schwann cells, and enhanced neurite growth from dorsal root ganglion explants. These findings suggest that paracrine action may be a key mechanism underlying the effects of hUCMSCs in peripheral nerve repair.

  14. Gypenosides causes DNA damage and inhibits expression of DNA repair genes of human oral cancer SAS cells.

    Science.gov (United States)

    Lu, Kung-Wen; Chen, Jung-Chou; Lai, Tung-Yuan; Yang, Jai-Sing; Weng, Shu-Wen; Ma, Yi-Shih; Tang, Nou-Ying; Lu, Pei-Jung; Weng, Jing-Ru; Chung, Jing-Gung

    2010-01-01

    Gypenosides (Gyp) are the major components of Gynostemma pentaphyllum Makino, a Chinese medical plant. Recently, Gyp has been shown to induce cell cycle arrest and apoptosis in many human cancer cell lines. However, there is no available information to address the effects of Gyp on DNA damage and DNA repair-associated gene expression in human oral cancer cells. Therefore, we investigated whether Gyp induced DNA damage and DNA repair gene expression in human oral cancer SAS cells. The results from flow cytometric assay indicated that Gyp-induced cytotoxic effects led to a decrease in the percentage of viable SAS cells. The results from comet assay revealed that the incubation of SAS cells with Gyp led to a longer DNA migration smear (comet tail) when compared with control and this effect was dose-dependent. The results from real-time PCR analysis indicated that treatment of SAS cells with 180 mug/ml of Gyp for 24 h led to a decrease in 14-3-3sigma, DNA-dependent serine/threonine protein kinase (DNAPK), p53, ataxia telangiectasia mutated (ATM), ataxia-telangiectasia and Rad3-related (ATR) and breast cancer gene 1 (BRCA1) mRNA expression. These observations may explain the cell death caused by Gyp in SAS cells. Taken together, Gyp induced DNA damage and inhibited DNA repair-associated gene expressions in human oral cancer SAS cells in vitro.

  15. Repair activity of oxidatively damaged DNA and telomere length in human lung epithelial cells after exposure to multi-walled carbon nanotubes

    DEFF Research Database (Denmark)

    Borghini, Andrea; Roursgaard, Martin; Andreassi, Maria Grazia;

    2017-01-01

    the cells toward replicative senescence, assessed by attrition of telomeres. To investigate this, H2O2 and KBrO3 were used to induce DNA damage in the cells and the effect of pre-exposure to MWCNT tested for a change in repair activity inside the cells or in the extract of treated cells. The effect of MWCNT...... exposure on telomere length was investigated for concentration and time response. We report a significantly increased repair activity in A549 cells exposed to MWCNTs compared to non-exposed cells, suggesting that DNA repair activity may be influenced by exposure to MWCNTs. The telomere length was decreased...

  16. Fuel supply of direct carbon fuel cells via thermal decomposition of hydrocarbons inside a porous Ni anode

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Hak Gyu; Li, Cheng Guo; Jalalabadi, Tahereh; Lee, Dong Geun [School of Mechanical Engineering, Pusan National University, Busan (Korea, Republic of)

    2015-06-15

    This study offers a novel method for improving the physical contact between the anode and fuel in a direct carbon fuel cell (DCFC): a direct generation of carbon in a porous Ni anode through the thermal decomposition of gaseous hydrocarbons. Three kinds of alkane hydrocarbons with different carbon numbers (CH4, C2H6, and C3H8) are tested. From electron microscope observations of the carbon particles generated from each hydrocarbon, we confirm that more carbon spheres (CS), carbon nanotubes (CNT), and carbon nanofibers (CNF) were identified with increasing carbon number. Raman scattering results revealed that the carbon samples became less crystalline and more flexible with increasing carbon number. DCFC performance was measured at 700 degree Celsius with the anode fueled by the same mass of each carbon sample. One-dimensional carbon fuels of CNT and CNF more actively produced and had power densities 148 and 210 times higher than that of the CS, respectively. This difference is partly attributed to the findings that the less-crystalline CNT and CNF have much lower charge transfer resistances than the CS.

  17. Dioxin exposure blocks lactation through a direct effect on mammary epithelial cells mediated by the aryl hydrocarbon receptor repressor.

    Science.gov (United States)

    Basham, Kaitlin J; Leonard, Christopher J; Kieffer, Collin; Shelton, Dawne N; McDowell, Maria E; Bhonde, Vasudev R; Looper, Ryan E; Welm, Bryan E

    2015-01-01

    In mammals, lactation is a rich source of nutrients and antibodies for newborn animals. However, millions of mothers each year experience an inability to breastfeed. Exposure to several environmental toxicants, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), has been strongly implicated in impaired mammary differentiation and lactation. TCDD and related polyhalogenated aromatic hydrocarbons are widespread industrial pollutants that activate the aryl hydrocarbon receptor (AHR). Despite many epidemiological and animal studies, the molecular mechanism through which AHR signaling blocks lactation remains unclear. We employed in vitro models of mammary differentiation to recapitulate lactogenesis in the presence of toxicants. We demonstrate AHR agonists directly block milk production in isolated mammary epithelial cells. Moreover, we define a novel role for the aryl hydrocarbon receptor repressor (AHRR) in mediating this response. Our mechanistic studies suggest AHRR is sufficient to block transcription of the milk gene β-casein. As TCDD is a prevalent environmental pollutant that affects women worldwide, our results have important public health implications for newborn nutrition.

  18. Platelet-rich plasma-induced bone marrow mesenchymal stem cells versus autologous nerve grafting for sciatic nerve repair

    Institute of Scientific and Technical Information of China (English)

    Changsuo Xia; Yajuan Li; Wen Cao; Zhaohua Yu

    2010-01-01

    Autologous nerve grafting is the gold standard of peripheral nerve repair.We previously showed that autologous platelet-rich plasma(PRP)contains high concentrations of growth factors and can induce in vitro cultured bone marrow mesenchymal stem cells(BMSCs)to differentiate into Schwann cells.Here we used PRP-induced BMSCs combined with chemically extracted acellular nerves to repair sciatic nerve defects and compared the effect with autologous nerve grafting.The BMSCs and chemically extracted acellular nerve promoted target muscle wet weight restoration,motor nerve conduction velocity,and axonal and myelin sheath regeneration,with similar effectiveness to autologous nerve grafting.This finding suggests that PRP induced BMSCs can be used to repair peripheral nerve defects.

  19. The self-construction and -repair of a foraging organism by explicitly specified development from a single cell.

    Science.gov (United States)

    Roth, Fabian; Siegelmann, Hava; Douglas, Rodney J

    2007-01-01

    As man-made systems become more complex and autonomous, there is a growing need for novel engineering methods that offer self-construction, adaptation to the environment, and self-repair. In a step towards developing such methods, we demonstrate how a simple model multicellular organism can assemble itself by replication from a single cell and finally express a fundamental behavior: foraging. Previous studies have employed evolutionary approaches to this problem. Instead, we aim at explicit design of self-constructing and -repairing systems by hierarchical specification of elementary intracellular mechanisms via a kind of genetic code. The interplay between individual cells and the gradually increasing self-created complexity of the local structure that surrounds them causes the serial unfolding of the final functional organism. The developed structure continuously feeds back to the development process, and so the system is also capable of self-repair.

  20. Synergistic decrease of DNA single-strand break repair rates in mouse neural cells lacking both Tdp1 and aprataxin

    Science.gov (United States)

    El-Khamisy, Sherif F.; Katyal, Sachin; Patel, Poorvi; Ju, Limei; McKinnon, Peter J.; Caldecott, Keith W.

    2009-01-01

    Ataxia oculomotor apraxia-1 (AOA1) is an autosomal recessive neurodegenerative disease that results from mutations of aprataxin (APTX). APTX associates with the DNA single- and double-strand break repair machinery and is able to remove AMP from 5′-termini at DNA strand breaks in vitro. However, attempts to establish a DNA strand break repair defect in APTX-defective cells have proved conflicting and unclear. We reasoned that this may reflect that DNA strand breaks with 5′-AMP represent only a minor subset of breaks induced in cells, and/or the availability of alternative mechanisms for removing AMP from 5′-termini. Here, we have attempted to increase the dependency of chromosomal single- and double-strand break repair on aprataxin activity by slowing the rate of repair of 3′-termini in aprataxin-defective neural cells, thereby increasing the likelihood that the 5′-termini at such breaks become adenylated and/or block alternative repair mechanisms. To do this, we generated a mouse model in which APTX is deleted together with tyrosyl DNA phosphodiesterase (TDP1), an enzyme that repairs 3′-termini at a subset of single-strand breaks (SSBs), including those with 3′-topoisomerase-1 (Top1) peptide. Notably, the global rate of repair of oxidative and alkylation-induced SSBs was significantly slower in Tdp1−/−/Aptx−/− double knockout quiescent mouse astrocytes compared with Tdp1−/− or Aptx−/− single knockouts. In contrast, camptothecin-induced Top1-SSBs accumulated to similar levels in Tdp1−/− and Tdp1−/−/Aptx−/− double knockout astrocytes. Finally, we failed to identify a measurable defect in double-strand break repair in Tdp1−/−, Aptx−/− or Tdp1−/−/Aptx−/− astrocytes. These data provide direct evidence for a requirement for aprataxin during chromosomal single-strand break repair in primary neural cells lacking Tdp1. PMID:19303373

  1. Aromatic Hydrocarbon Receptor Suppresses Prostate Cancer Bone Metastasis Cells-Induced Vasculogenesis of Endothelial Progenitor Cells under Hypoxia

    Directory of Open Access Journals (Sweden)

    Shuai Huang

    2016-07-01

    Full Text Available Background/Aims: Hypoxia leads to the development of neovascularization in solid tumor by regulating VEGF expression. Aromatic hydrocarbon receptor (AHR, a receptor for dioxin-like compounds, functions as a transcription factor through dimerization with hypoxia-inducible factors 1β (HIF-1β and inhibits the secretion of vascular endothelial growth factor (VEGF. The purpose of this study was to explore whether AHR can suppress hypoxia-induced VEGF production in prostate bone metastasis cells and repress neovascularization in endothelial progenitor cells (EPCs, and, if so, through what mechanisms. Methods: PC-3 or LNCaP cells induced angiogenesis was detected by Matrigel-based tube formation assay, mRNA expression levels was measured by qRT-PCR, VEGF secretion level was determined by ELISA assay, respectively. Results: AHR activation inhibits hypoxia-induced adhesiveness and vasculogenesis of EPCs induced by PC-3 or LNCaP cells under hypoxia. Moreover, AHR activation suppressed hypoxia-induced VEGF production in PC-3 and LNCaP cells (48 ± 14% in PC-3, p = 0.000; 41 ± 14% in LNCaP, p = 0.000 by attenuating HIF-1α and HIF-1β level that in turn diminished the angiogenic ability of EPCs in vitro. Furthermore, we found the mRNA level of hypoxia-inducible factors 1α (HIF-1α (1.54 ± 0.13 fold in PC-3, p = 0.002, 1.62 ± 0.12 fold in LNCaP, p = 0.001 and HIF-1β (1.67 ± 0.23 fold in PC-3, p = 0.007; 1.75 ± 0.26 fold in LNCaP, p=0.008 were upregulated in prostate cancer bone metastasis PC-3 and LNCaP cell lines in response to hypoxia, and revealed that the regulation of VEGF by HIF-1α and HIF-1β was possibly mediated by the activation of phosphatidylinositol 3-kinase pathway. Conclusion: By providing a mechanistic insight into the modulation of neovascularization by AHR ligand, we suggest that AHR ligand has a strong potential of being a new therapeutic agent with applications in the field of bone metastatic prostate cancer.

  2. Expression of various growth factors for cell proliferation and cytodifferentiation during fracture repair of bone

    Directory of Open Access Journals (Sweden)

    M Fukuda

    2009-12-01

    Full Text Available We examined immunohistochemically the fracture repair process in rat tibial bone using antibodies to PCNA, BMP2, TGF-b 1,-2,-3, TGF-b R1,- R2, bFGF, bFGFR, PDGF, VEGF, and S-100. The peak level of cell proliferation as revealed by PCNA labelling appeared first in primitive mesenchymal cells and inflammatory cells at the fracture edges and neighboring periosteum at 2-days after fracture, followed by the peaks of periosteal primitive fibroblasts and chondroblasts, which appeared at fracture edges at 3- and 4-days after fracture, respectively. BMP2 was weakly positive in primitive mesenchymal cells, osteoblasts and chondroblasts. At 3-days post-fracture, periosteal osteoblasts produced osteoid tissue and callus with marrow spaces lined by osteoblasts and osteoclasts, and all primitive mesenchymal cells and osteoblasts were positive for TGF-b 1,-2,-3, and TGF-b R1,-R2. They were also positive for vascular growth factors bFGF, FGFR and PDGF, but negative for VEGF, and the peak of PCNA labelling of vascular endothelial cells in the marrow space was delayed to 4-days after fracture. Chondroblasts at fracture edges produced hypertrophic chondrocytes at 5-days after fracture and they were positive for TGF-b 1,-2,-3, and TGF-b R1,-R2. Primitive chondroblasts were positive for vascular growth factors VEGF as well as bFGF, FGFR, and the peak of PCNA labelling of vascular endothelial cells in the cartilage was at 5-days after fracture. Hypertrophic chondrocytes were also positive for these growth factors but negative for bFGF and bFGFR. S-100 protein-induced calcification was only positive on chondroblasts and hypertrophic chondrocytes. At 7-days after fracture, bone began to be formed from the cartilage at fracture edges, by a process similar to bone formation in the growth plate. Enchondral ossification established a bridge between both fracture edges and periosteal membranous ossification encompassed the fracture site like a sheath at 14- day after

  3. Identification of small molecule inhibitors of ERCC1-XPF that inhibit DNA repair and potentiate cisplatin efficacy in cancer cells.

    Science.gov (United States)

    Arora, Sanjeevani; Heyza, Joshua; Zhang, Hao; Kalman-Maltese, Vivian; Tillison, Kristin; Floyd, Ashley M; Chalfin, Elaine M; Bepler, Gerold; Patrick, Steve M

    2016-11-15

    ERCC1-XPF heterodimer is a 5'-3' structure-specific endonuclease which is essential in multiple DNA repair pathways in mammalian cells. ERCC1-XPF (ERCC1-ERCC4) repairs cisplatin-DNA intrastrand adducts and interstrand crosslinks and its specific inhibition has been shown to enhance cisplatin cytotoxicity in cancer cells. In this study, we describe a high throughput screen (HTS) used to identify small molecules that inhibit the endonuclease activity of ERCC1-XPF. Primary screens identified two compounds that inhibit ERCC1-XPF activity in the nanomolar range. These compounds were validated in secondary screens against two other non-related endonucleases to ensure specificity. Results from these screens were validated using an in vitro gel-based nuclease assay. Electrophoretic mobility shift assays (EMSAs) further show that these compounds do not inhibit the binding of purified ERCC1-XPF to DNA. Next, in lung cancer cells these compounds potentiated cisplatin cytotoxicity and inhibited DNA repair. Structure activity relationship (SAR) studies identified related compounds for one of the original Hits, which also potentiated cisplatin cytotoxicity in cancer cells. Excitingly, dosing with NSC16168 compound potentiated cisplatin antitumor activity in a lung cancer xenograft model. Further development of ERCC1-XPF DNA repair inhibitors is expected to sensitize cancer cells to DNA damage-based chemotherapy.

  4. Ndrg3 gene regulates DSB repair during meiosis through modulation the ERK signal pathway in the male germ cells

    Science.gov (United States)

    Pan, Hongjie; Zhang, Xuan; Jiang, Hanwei; Jiang, Xiaohua; Wang, Liu; Qi, Qi; Bi, Yuan; Wang, Jian; Shi, Qinghua; Li, Runsheng

    2017-01-01

    The N-myc downstream regulated gene (NDRG) family consists of 4 members, NDRG-1, -2, -3, -4. Physiologically, we found Ndrg3, a critical gene which led to homologous lethality in the early embryo development, regulated the male meiosis in mouse. The expression of Ndrg3 was enhanced specifically in germ cells, and reached its peak level in the pachytene stage spermatocyte. Haplo-insufficiency of Ndrg3 gene led to sub-infertility during the male early maturation. In the Ndrg3+/− germ cells, some meiosis events such as DSB repair and synaptonemal complex formation were impaired. Disturbances on meiotic prophase progression and spermatogenesis were observed. In mechanism, the attenuation of pERK1/2 signaling was detected in the heterozygous testis. With our primary spermatocyte culture system, we found that lactate promoted DSB repair via ERK1/2 signaling in the male mouse germ cells in vitro. Deficiency of Ndrg3 gene attenuated the activation of ERK which further led to the aberrancy of DSB repair in the male germ cells in mouse. Taken together, we reported that Ndrg3 gene modulated the lactate induced ERK pathway to facilitate DSB repair in male germ cells, which further regulated meiosis and subsequently fertility in male mouse. PMID:28290521

  5. Ndrg3 gene regulates DSB repair during meiosis through modulation the ERK signal pathway in the male germ cells.

    Science.gov (United States)

    Pan, Hongjie; Zhang, Xuan; Jiang, Hanwei; Jiang, Xiaohua; Wang, Liu; Qi, Qi; Bi, Yuan; Wang, Jian; Shi, Qinghua; Li, Runsheng

    2017-03-14

    The N-myc downstream regulated gene (NDRG) family consists of 4 members, NDRG-1, -2, -3, -4. Physiologically, we found Ndrg3, a critical gene which led to homologous lethality in the early embryo development, regulated the male meiosis in mouse. The expression of Ndrg3 was enhanced specifically in germ cells, and reached its peak level in the pachytene stage spermatocyte. Haplo-insufficiency of Ndrg3 gene led to sub-infertility during the male early maturation. In the Ndrg3(+/-) germ cells, some meiosis events such as DSB repair and synaptonemal complex formation were impaired. Disturbances on meiotic prophase progression and spermatogenesis were observed. In mechanism, the attenuation of pERK1/2 signaling was detected in the heterozygous testis. With our primary spermatocyte culture system, we found that lactate promoted DSB repair via ERK1/2 signaling in the male mouse germ cells in vitro. Deficiency of Ndrg3 gene attenuated the activation of ERK which further led to the aberrancy of DSB repair in the male germ cells in mouse. Taken together, we reported that Ndrg3 gene modulated the lactate induced ERK pathway to facilitate DSB repair in male germ cells, which further regulated meiosis and subsequently fertility in male mouse.

  6. An inverse switch in DNA base excision and strand break repair contributes to melphalan resistance in multiple myeloma cells.

    Directory of Open Access Journals (Sweden)

    Mirta M L Sousa

    Full Text Available Alterations in checkpoint and DNA repair pathways may provide adaptive mechanisms contributing to acquired drug resistance. Here, we investigated the levels of proteins mediating DNA damage signaling and -repair in RPMI8226 multiple myeloma cells and its Melphalan-resistant derivative 8226-LR5. We observed markedly reduced steady-state levels of DNA glycosylases UNG2, NEIL1 and MPG in the resistant cells and cross-resistance to agents inducing their respective DNA base lesions. Conversely, repair of alkali-labile sites was apparently enhanced in the resistant cells, as substantiated by alkaline comet assay, autoribosylation of PARP-1, and increased sensitivity to PARP-1 inhibition by 4-AN or KU58684. Reduced base-excision and enhanced single-strand break repair would both contribute to the observed reduction in genomic alkali-labile sites, which could jeopardize productive processing of the more cytotoxic Melphalan-induced interstrand DNA crosslinks (ICLs. Furthermore, we found a marked upregulation of proteins in the non-homologous end-joining (NHEJ pathway of double-strand break (DSB repair, likely contributing to the observed increase in DSB repair kinetics in the resistant cells. Finally, we observed apparent upregulation of ATR-signaling and downregulation of ATM-signaling in the resistant cells. This was accompanied by markedly increased sensitivity towards Melphalan in the presence of ATR-, DNA-PK, or CHK1/2 inhibitors whereas no sensitizing effect was observed subsequent to ATM inhibition, suggesting that replication blocking lesions are primary triggers of the DNA damage response in the Melphalan resistant cells. In conclusion, Melphalan resistance is apparently contributed by modulation of the DNA damage response at multiple levels, including downregulation of specific repair pathways to avoid repair intermediates that could impair efficient processing of cytotoxic ICLs and ICL-induced DSBs. This study has revealed several novel

  7. Positive regulation of DNA double strand break repair activity during differentiation of long life span cells: the example of adipogenesis.

    Directory of Open Access Journals (Sweden)

    Aline Meulle

    Full Text Available Little information is available on the ability of terminally differentiated cells to efficiently repair DNA double strand breaks (DSBs, and one might reasonably speculate that efficient DNA repair of these threatening DNA lesions, is needed in cells of long life span with no or limited regeneration from precursor. Few tissues are available besides neurons that allow the study of DNA DSBs repair activity in very long-lived cells. Adipocytes represent a suitable model since it is generally admitted that there is a very slow turnover of adipocytes in adult. Using both Pulse Field Gel Electrophoresis (PFGE and the disappearance of the phosphorylated form of the histone variant H2AX, we demonstrated that the ability to repair DSBs is increased during adipocyte differentiation using the murine pre-adipocyte cell line, 3T3F442A. In mammalian cells, DSBs are mainly repaired by the non-homologous end-joining pathway (NHEJ that relies on the DNA dependent protein kinase (DNA-PK activity. During the first 24 h following the commitment into adipogenesis, we show an increase in the expression and activity of the catalytic sub-unit of the DNA-PK complex, DNA-PKcs. The increased in DNA DSBs repair activity observed in adipocytes was due to the increase in DNA-PK activity as shown by the use of DNA-PK inhibitor or sub-clones of 3T3F442A deficient in DNA-PKcs using long term RNA interference. Interestingly, the up-regulation of DNA-PK does not regulate the differentiation program itself. Finally, similar positive regulation of DNA-PKcs expression and activity was observed during differentiation of primary culture of pre-adipocytes isolated from human sub-cutaneous adipose tissue. Our results show that DNA DSBs repair activity is up regulated during the early commitment into adipogenesis due to an up-regulation of DNA-PK expression and activity. In opposition to the general view that DNA DSBs repair is decreased during differentiation, our results demonstrate

  8. Role of Endothelial Differentiated Adipose-derived Stem Cells in Repairing Calvarial Critical Size Defects in the Laboratory Rat (Rattus norvegicus)

    Science.gov (United States)

    2014-07-16

    Differentiated Adipose-derived Stem Cells in Repairing Calvarial Critical Size Defects in the Laboratory Rat (Rattus norvegicus) PRINCIPAL INVESTIGATOR...SUBTITLE FDG20110033A "Role of Endothelial Differentiated Adipose-derived Stem Cells in Repairing Calvarial Critical Size Defects in the Laboratory Rat (Rattus

  9. Tumor cell death mediated by peptides that recognize branched intermediates of DNA replication and repair.

    Directory of Open Access Journals (Sweden)

    Mamon Dey

    Full Text Available Effective treatments for cancer are still needed, both for cancers that do not respond well to current therapeutics and for cancers that become resistant to available treatments. Herein we investigated the effect of a structure-selective d-amino acid peptide wrwycr that binds replication fork mimics and Holliday Junction (HJs intermediates of homologous recombination (HR in vitro, and inhibits their resolution by HJ-processing enzymes. We predicted that treating cells with HJ-binding compounds would lead to accumulation of DNA damage. As cells repair endogenous or exogenous DNA damage, collapsed replication forks and HJ intermediates will accumulate and serve as targets for the HJ-binding peptides. Inhibiting junction resolution will lead to further accumulation of DNA breaks, eventually resulting in amplification of the damage and causing cell death. Both peptide wrwycr and the related wrwyrggrywrw entered cancer cells and reduced cell survival in a dose- and time-dependent manner. Early markers for DNA damage, γH2AX foci and 53BP1 foci, increased with dose and/or time exposure to the peptides. DNA breaks persisted at least 48 h, and both checkpoint proteins Chk1 and Chk2 were activated. The passage of the cells from S to G2/M was blocked even after 72 h. Apoptosis, however, was not induced in either HeLa or PC3 cells. Based on colony-forming assays, about 35% peptide-induced cytotoxicity was irreversible. Finally, sublethal doses of peptide wrwycr (50-100 µM in conjunction with sublethal doses of several DNA damaging agents (etoposide, doxorubicin, and HU reduced cell survival at least additively and sometimes synergistically. Taken together, the results suggest that the peptides merit further investigation as proof-of-principle molecules for a new class of anti-cancer therapeutics, in particular in combination with other DNA damaging therapies.

  10. Tumor cell death mediated by peptides that recognize branched intermediates of DNA replication and repair.

    Science.gov (United States)

    Dey, Mamon; Patra, Sukanya; Su, Leo Y; Segall, Anca M

    2013-01-01

    Effective treatments for cancer are still needed, both for cancers that do not respond well to current therapeutics and for cancers that become resistant to available treatments. Herein we investigated the effect of a structure-selective d-amino acid peptide wrwycr that binds replication fork mimics and Holliday Junction (HJs) intermediates of homologous recombination (HR) in vitro, and inhibits their resolution by HJ-processing enzymes. We predicted that treating cells with HJ-binding compounds would lead to accumulation of DNA damage. As cells repair endogenous or exogenous DNA damage, collapsed replication forks and HJ intermediates will accumulate and serve as targets for the HJ-binding peptides. Inhibiting junction resolution will lead to further accumulation of DNA breaks, eventually resulting in amplification of the damage and causing cell death. Both peptide wrwycr and the related wrwyrggrywrw entered cancer cells and reduced cell survival in a dose- and time-dependent manner. Early markers for DNA damage, γH2AX foci and 53BP1 foci, increased with dose and/or time exposure to the peptides. DNA breaks persisted at least 48 h, and both checkpoint proteins Chk1 and Chk2 were activated. The passage of the cells from S to G2/M was blocked even after 72 h. Apoptosis, however, was not induced in either HeLa or PC3 cells. Based on colony-forming assays, about 35% peptide-induced cytotoxicity was irreversible. Finally, sublethal doses of peptide wrwycr (50-100 µM) in conjunction with sublethal doses of several DNA damaging agents (etoposide, doxorubicin, and HU) reduced cell survival at least additively and sometimes synergistically. Taken together, the results suggest that the peptides merit further investigation as proof-of-principle molecules for a new class of anti-cancer therapeutics, in particular in combination with other DNA damaging therapies.

  11. Characterization of environmental chemicals with potential for DNA damage using isogenic DNA repair-deficient chicken DT40 cell lines.

    Science.gov (United States)

    Yamamoto, Kimiyo N; Hirota, Kouji; Kono, Koichi; Takeda, Shunichi; Sakamuru, Srilatha; Xia, Menghang; Huang, Ruili; Austin, Christopher P; Witt, Kristine L; Tice, Raymond R

    2011-08-01

    Included among the quantitative high throughput screens (qHTS) conducted in support of the US Tox21 program are those being evaluated for the detection of genotoxic compounds. One such screen is based on the induction of increased cytotoxicity in seven isogenic chicken DT40 cell lines deficient in DNA repair pathways compared to the parental DNA repair-proficient cell line. To characterize the utility of this approach for detecting genotoxic compounds and identifying the type(s) of DNA damage induced, we evaluated nine of 42 compounds identified as positive for differential cytotoxicity in qHTS (actinomycin D, adriamycin, alachlor, benzotrichloride, diglycidyl resorcinol ether, lovastatin, melphalan, trans-1,4-dichloro-2-butene, tris(2,3-epoxypropyl)isocyanurate) and one non-cytotoxic genotoxic compound (2-aminothiamine) for (1) clastogenicity in mutant and wild-type cells; (2) the comparative induction of γH2AX positive foci by melphalan; (3) the extent to which a 72-hr exposure duration increased assay sensitivity or specificity; (4) the use of 10 additional DT40 DNA repair-deficient cell lines to better analyze the type(s) of DNA damage induced; and (5) the involvement of reactive oxygen species in the induction of DNA damage. All compounds but lovastatin and 2-aminothiamine were more clastogenic in at least one DNA repair-deficient cell line than the wild-type cells. The differential responses across the various DNA repair-deficient cell lines provided information on the type(s) of DNA damage induced. The results demonstrate the utility of this DT40 screen for detecting genotoxic compounds, for characterizing the nature of the DNA damage, and potentially for analyzing mechanisms of mutagenesis.

  12. Bisdemethoxycurcumin induces DNA damage and inhibits DNA repair associated protein expressions in NCI-H460 human lung cancer cells.

    Science.gov (United States)

    Yu, Chien-Chih; Yang, Su-Tso; Huang, Wen-Wen; Peng, Shu-Fen; Huang, An-Cheng; Tang, Nou-Ying; Liu, Hsin-Chung; Yang, Mei-Due; Lai, Kuang-Chi; Chung, Jing-Gung

    2016-12-01

    Nonsmall cell lung carcinoma (NSCLC) is a devastating primary lung tumor resistant to conventional therapies. Bisdemethoxycurcumin (BDMC) is one of curcumin derivate from Turmeric and has been shown to induce NSCLC cell death. Although there is one report to show BDMC induced DNA double strand breaks, however, no available information to show BDMC induced DNA damage action with inhibited DNA repair protein in lung cancer cells in detail. In this study, we tested BDMC-induced DNA damage and condensation in NCI-H460 cells by using Comet assay and DAPI staining examinations, respectively and we found BDMC induced DNA damage and condension. Western blotting was used to examine the effects of BDMC on protein expression associated with DNA damage and repair and results indicated that BDMC suppressed the protein levels associated with DNA damage and repair, such as 14-3-3σ (an important checkpoint keeper of DDR), O6-methylguanine-DNA methyltransferase, DNA repair proteins breast cancer 1, early onset, mediator of DNA damage checkpoint 1 but activate phosphorylated p53 and p-H2A.X (phospho Ser140) in NCI-H460 cells. Confocal laser systems microscopy was used for examining the protein translocation and results show that BDMC increased the translocation of p-p53 and p-H2A.X (phospho Ser140) from cytosol to nuclei in NCI-H460 cells. In conclusion, BDMC induced DNA damage and condension and affect DNA repair proteins in NCI-H460 cells in vitro. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1859-1868, 2016. © 2015 Wiley Periodicals, Inc.

  13. The MET Receptor Tyrosine Kinase Confers Repair of Murine Pancreatic Acinar Cells following Acute and Chronic Injury

    Science.gov (United States)

    Gaziova, Ivana; Jackson, Daniel; Boor, Paul J.; Carter, Dwayne; Cruz-Monserrate, Zobeida; Elferink, Cornelis J.; Joshi, Aditya D.; Kaphalia, Bhupendra; Logsdon, Craig D.; Pereira de Castro, Karen; Soong, Lynn; Tao, Xinrong; Qiu, Suimin; Elferink, Lisa A.

    2016-01-01

    Acinar cells represent the primary target in necroinflammatory diseases of the pancreas, including pancreatitis. The signaling pathways guiding acinar cell repair and regeneration following injury remain poorly understood. The purpose of this study was to determine the importance of Hepatocyte Growth Factor Receptor/MET signaling as an intrinsic repair mechanism for acinar cells following acute damage and chronic alcohol-associated injury. Here, we generated mice with targeted deletion of MET in adult acinar cells (MET-/-). Acute and repetitive pancreatic injury was induced in MET-/- and control mice with cerulein, and chronic injury by feeding mice Lieber-DeCarli diets containing alcohol with or without enhancement of repetitive pancreatic injury. We examined the exocrine pancreas of these mice histologically for acinar death, edema, inflammation and collagen deposition and changes in the transcriptional program. We show that MET expression is relatively low in normal adult pancreas. However, MET levels were elevated in ductal and acinar cells in human pancreatitis specimens, consistent with a role for MET in an adaptive repair mechanism. We report that genetic deletion of MET in adult murine acinar cells was linked to increased acinar cell death, chronic inflammation and delayed recovery (regeneration) of pancreatic exocrine tissue. Notably, increased pancreatic collagen deposition was detected in MET knockout mice following repetitive injury as well alcohol-associated injury. Finally, we identified specific alterations of the pancreatic transcriptome associated with MET signaling during injury, involved in tissue repair, inflammation and endoplasmic reticulum stress. Together, these data demonstrate the importance of MET signaling for acinar repair and regeneration, a novel finding that could attenuate the symptomology of pancreatic injury. PMID:27798657

  14. A sensitive test for the detection of specific DSB repair defects in primary cells from breast cancer specimens.

    Science.gov (United States)

    Keimling, Marlen; Kaur, Jatinder; Bagadi, Sarangadhara Appala Raju; Kreienberg, Rolf; Wiesmüller, Lisa; Ralhan, Ranju

    2008-08-01

    Increasing evidence indicates that breast cancer pathogenesis is linked with DNA double-strand break (DSB) repair dysfunction. This conclusion is based on advances in the study of functions of breast cancer susceptibility genes such as BRCA1 and BRCA2, on the identification of breast cancer-associated changes regarding the genetics, expression, and localization of multiple DSB repair factors, and on observations indicating enhanced radiation-induced chromosomal damage in cells from predisposed individuals and sporadic breast cancer patients. In this pilot study, we describe a sensitive method for the analysis of DSB repair functions in mammary carcinomas. Using this method we firstly document alterations in pathway-specific DSB repair activities in primary cells originating from familial as well as sporadic breast cancer. In particular, we identified increases in the mutagenic nonhomologous end joining and single-strand annealing mechanisms in sporadic breast cancers with wild-type BRCA1 and BRCA2, and, thus, similar phenotypes to tumors with mutant alleles of BRCA1 and BRCA2. This suggests that detection of error-prone DSB repair activities may be useful to extend the limits of genotypic characterization of high-risk susceptibility genes. This method may, therefore, serve as a marker for breast cancer risk assessment and, even more importantly, for the prediction of responsiveness to targeted therapies such as to inhibitors of poly(ADP-ribose)polymerase (PARP1).

  15. Alzheimer’s Disease-Associated Neurotoxic Peptide Amyloid-Β Impairs Base Excision Repair in Human Neuroblastoma Cells

    Directory of Open Access Journals (Sweden)

    Anne Forestier

    2012-11-01

    Full Text Available Alzheimer’s disease (AD is the leading cause of dementia in developed countries. It is characterized by two major pathological hallmarks, one of which is the extracellular aggregation of the neurotoxic peptide amyloid-β (Aβ, which is known to generate oxidative stress. In this study, we showed that the presence of Aβ in a neuroblastoma cell line led to an increase in both nuclear and mitochondrial DNA damage. Unexpectedly, a concomitant decrease in basal level of base excision repair, a major route for repairing oxidative DNA damage, was observed at the levels of both gene expression and protein activity. Moreover, the addition of copper sulfate or hydrogen peroxide, used to mimic the oxidative stress observed in AD-affected brains, potentiates Aβ-mediated perturbation of DNA damage/repair systems in the “Aβ cell line”. Taken together, these findings indicate that Aβ could act as double-edged sword by both increasing oxidative nuclear/mitochondrial damage and preventing its repair. The synergistic effects of increased ROS production, accumulated DNA damage and impaired DNA repair could participate in, and partly explain, the massive loss of neurons observed in Alzheimer’s disease since both oxidative stress and DNA damage can trigger apoptosis.

  16. Combination of CD34-positive cell subsets with infarcted myocardium-like matrix stiffness: a potential solution to cell-based cardiac repair.

    Science.gov (United States)

    Zhang, Shuning; Ma, Xin; Yao, Kang; Zhu, Hong; Huang, Zheyong; Shen, Li; Qian, Juying; Zou, Yunzeng; Sun, Aijun; Ge, Junbo

    2014-06-01

    Detection of the optimal cell transplantation strategy for myocardial infarction (MI) has attracted a great deal of attention. Commitment of engrafted cells to angiogenesis within damaged myocardium is regarded as one of the major targets in cell-based cardiac repair. Bone marrow-derived CD34-positive cells, a well-characterized population of stem cells, might represent highly functional endothelial progenitor cells and result in the formation of new blood vessels. Recently, physical microenvironment (extracellular matrix stiffness) around the engrafted cells was found to exert an essential impact on their fate. Stem cells are able to feel and respond to the tissue-like matrix stiffness to commit to a relevant lineage. Notably, the infarct area after MI experiences a time-dependent stiffness change from flexible to rigid. Our previous observations demonstrated myocardial stiffness-dependent differentiation of the unselected bone marrow-derived mononuclear cells (BMMNCs) along endothelial lineage cells. Myocardial stiffness (~42 kPa) within the optimal time domain of cell engraftment (at week 1 to 2) after MI provided a more favourable physical microenvironment for cell specification and cell-based cardiac repair. However, the difference in tissue stiffness-dependent cell differentiation between the specific cell subsets expressing and no expressing CD34 phenotype remains uncertain. We presumed that CD34-positive cell subsets facilitated angiogenesis and subsequently resulted in cardiac repair under induction of infarcted myocardium-like matrix stiffness compared with CD34-negative cells. If the hypothesis were true, it would contribute greatly to detect the optimal cell subsets for cell therapy and to establish an optimized therapy strategy for cell-based cardiac repair.

  17. Chondroitinase ABC plus bone marrow mesenchymal stem cells for repair of spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    Chun Zhang; Xijing He; Haopeng Li; Guoyu Wang

    2013-01-01

    As chondroitinase ABC can improve the hostile microenvironment and cell transplantation is proven to be effective after spinal cord injury, we hypothesized that their combination would be a more effective treatment option. At 5 days after T8 spinal cord crush injury, rats were injected with bone marrow mesenchymal stem cell suspension or chondroitinase ABC 1 mm from the edge of spinal cord damage zone. Chondroitinase ABC was first injected, and bone marrow mesenchymal stem cell suspension was injected on the next day in the combination group. At 14 days, the mean Basso, Beattie and Bresnahan score of the rats in the combination group was higher than other groups. Hematoxylin-eosin staining showed that the necrotic area was significantly reduced in the combination group compared with other groups. Glial fibrillary acidic protein-chondroitin sulfate proteoglycan double staining showed that the damage zone of astrocytic scars was significantly reduced without the cavity in the combination group. Glial fibrillary acidic protein/growth associated protein-43 double immunostaining revealed that positive fibers traversed the damage zone in the combination group. These results suggest that the combination of chondroitinase ABC and bone marrow mesenchymal stem cell transplantation contributes to the repair of spinal cord injury.

  18. A synergistic approach for neural repair: cell transplantation and induction of endogenous precursor cell activity.

    Science.gov (United States)

    Madhavan, Lalitha; Collier, Timothy J

    2010-05-01

    Stem cell research offers enormous potential for treating many diseases of the nervous system. At present, therapeutic strategies in stem cell research segregate into two approaches: cell transplantation or endogenous cell stimulation. Realistically, future cell therapies will most likely involve a combination of these two approaches, a theme of our current research. Here, we propose that there exists a 'synergy' between exogenous (transplanted) and endogenous stem cell actions that can be utilized to achieve therapeutic ends. Elucidating mechanisms underlying this exogenous-endogenous stem cell synergism may lead to the development of optimal cell therapies for neural disorders. Copyright 2009 Elsevier Ltd. All rights reserved.

  19. The combined use of mesenchymal stromal cells and scaffolds for bone repair.

    Science.gov (United States)

    Ciapetti, Gabriela; Granchi, Donatella; Baldini, Nicola

    2012-01-01

    A general principle of stem cell therapy is to exploit the natural ability of the human body to heal through the process of regeneration. Here, we review the current status of cell therapy based on adult mesenchymal stem cells (MSC) with emphasis on therapeutic application in bone-related diseases. The main issues for an effective bone engineering strategy include: - A sufficient number of bone-forming cells, where cell yield, separation, expansion, commitment, as well as patient age, are all variables to be considered; - An ECM-like scaffold conductive for and informative to cells, where structural/physico-chemical/mechanical parameters, administration form (injectable or free-form), and degradation rate have to be tuned according to the clinical application; - Biochemical signals, such as growth factors/cytokines to induce osteogenic differentiation, where the choice between autogenous or exogenous sourcing, dose, timing, etc. are critical; - An adequate blood supply, provided by angiogenetic factors, pre-vascularization, pre-implant co-culture of vessel and bone progenitors. We also discuss the safety and efficacy of different approaches, as well as bottlenecks hampering rapid translation of adult MSC therapy from the laboratories to the clinics. A central paradigm for the effective regeneration of bone tissue is the re-creation at the site of injury of a microenvironment as close as possible to the natural MSC repository in the body. This would allow adult MSC to serve as cellular factories, i.e. to express paracrine activity in situ by secretion of inflammatory and reparative cytokines and to cooperate with other cells. The results from a wide array of in vitro and in vivo studies, as well as from some clinical trials, are expanding the range of clinical protocols for bone repair, that is the ultimate goal of orthopaedics.

  20. Novel mechanism of regulation of the DNA repair enzyme OGG1 in tuberin-deficient cells

    Science.gov (United States)

    Habib, Samy L.; Bhandari, Besant K.; Sadek, Nahed; Abboud-Werner, Sherry L.; Abboud, Hanna E.

    2010-01-01

    Tuberin (protein encodes by tuberous sclerosis complex 2, Tsc2) deficiency is associated with the decrease in the DNA repair enzyme 8-oxoG-DNA glycosylase (OGG1) in tumour kidney of tuberous sclerosis complex (TSC) patients. The purpose of this study was to elucidate the mechanisms by which tuberin regulates OGG1. The partial deficiency in tuberin expression that occurs in the renal proximal tubular cells and kidney cortex of the Eker rat is associated with decreased activator protein 4 (AP4) and OGG1 expression. A complete deficiency in tuberin is associated with loss of AP4 and OGG1 expression in kidney tumour from Eker rats and the accumulation of significant levels of 8-oxo-deoxyguanosine. Knockdown of tuberin expression in human renal epithelial cells (HEK293) with small interfering RNA (siRNA) also resulted in a marked decrease in the expression of AP4 and OGG1. In contrast, overexpression of tuberin in HEK293 cells increased the expression of AP4 and OGG1 proteins. Downregulation of AP4 expression using siRNA resulted in a significant decrease in the protein expression of OGG1. Immunoprecipitation studies show that AP4 is associated with tuberin in cells. Gel shift analysis and chromatin immunoprecipitation identified the transcription factor AP4 as a positive regulator of the OGG1 promoter. AP4 DNA-binding activity is significantly reduced in Tsc2−/− as compared with Tsc2+/+ cells. Transcriptional activity of the OGG1 promoter is also decreased in tuberin-null cells compared with wild-type cells. These data indicate a novel role for tuberin in the regulation of OGG1 through the transcription factor AP4. This regulation may be important in the pathogenesis of kidney tumours in patients with TSC disease. PMID:20837600

  1. Repair Effect of Seaweed Polysaccharides with Different Contents of Sulfate Group and Molecular Weights on Damaged HK-2 Cells

    Directory of Open Access Journals (Sweden)

    Poonam Bhadja

    2016-05-01

    Full Text Available The structure–activity relationships and repair mechanism of six low-molecular-weight seaweed polysaccharides (SPSs on oxalate-induced damaged human kidney proximal tubular epithelial cells (HK-2 were investigated. These SPSs included Laminaria japonica polysaccharide, degraded Porphyra yezoensis polysaccharide, degraded Gracilaria lemaneiformis polysaccharide, degraded Sargassum fusiforme polysaccharide, Eucheuma gelatinae polysaccharide, and degraded Undaria pinnatifida polysaccharide. These SPSs have a narrow difference of molecular weight (from 1968 to 4020 Da after degradation by controlling H2O2 concentration. The sulfate group (–SO3H content of the six SPSs was 21.7%, 17.9%, 13.3%, 8.2%, 7.0%, and 5.5%, respectively, and the –COOH contents varied between 1.0% to 1.7%. After degradation, no significant difference was observed in the contents of characteristic –SO3H and –COOH groups of polysaccharides. The repair effect of polysaccharides was determined using cell-viability test by CCK-8 assay and cell-morphology test by hematoxylin-eosin staining. The results revealed that these SPSs within 0.1–100 μg/mL did not express cytotoxicity in HK-2 cells, and each polysaccharide had a repair effect on oxalate-induced damaged HK-2 cells. Simultaneously, the content of polysaccharide –SO3H was positively correlated with repair ability. Furthermore, the low-molecular-weight degraded polysaccharides showed better repair activity on damaged HK-2 cells than their undegraded counterpart. Our results can provide reference for inhibiting the formation of kidney stones and for developing original anti-stone polysaccharide drugs.

  2. Early passage bone marrow stromal cells express genes involved in nervous system development supporting their relevance for neural repair

    NARCIS (Netherlands)

    Nandoe, R.D.S.; Bossers, K.; Ritfeld, G.J.; Blits, B.; Grotenhuis, J.A.; Verhaagen, J.; Oudega, M.

    2011-01-01

    PURPOSE: The assessment of the capacity of bone marrow stromal cells (BMSC) to repair the nervous system using gene expression profiling. The evaluation of effects of long-term culturing on the gene expression profile of BMSC. METHODS: Fourty four k whole genome rat microarrays were used to study

  3. Overexpression of DNA ligase III in mitochondria protects cells against oxidative stress and improves mitochondrial DNA base excision repair.

    Science.gov (United States)

    Akbari, Mansour; Keijzers, Guido; Maynard, Scott; Scheibye-Knudsen, Morten; Desler, Claus; Hickson, Ian D; Bohr, Vilhelm A

    2014-04-01

    Base excision repair (BER) is the most prominent DNA repair pathway in human mitochondria. BER also results in a temporary generation of AP-sites, single-strand breaks and nucleotide gaps. Thus, incomplete BER can result in the generation of DNA repair intermediates that can disrupt mitochondrial DNA replication and transcription and generate mutations. We carried out BER analysis in highly purified mitochondrial extracts from human cell lines U2OS and HeLa, and mouse brain using a circular DNA substrate containing a lesion at a specific position. We found that DNA ligation is significantly slower than the preceding mitochondrial BER steps. Overexpression of DNA ligase III in mitochondria improved the rate of overall BER, increased cell survival after menadione induced oxidative stress and reduced autophagy following the inhibition of the mitochondrial electron transport chain complex I by rotenone. Our results suggest that the amount of DNA ligase III in mitochondria may be critical for cell survival following prolonged oxidative stress, and demonstrate a functional link between mitochondrial DNA damage and repair, cell survival upon oxidative stress, and removal of dysfunctional mitochondria by autophagy.

  4. Evaluation of Cartilage Repair by Mesenchymal Stem Cells Seeded on a PEOT/PBT Scaffold in an Osteochondral Defect

    NARCIS (Netherlands)

    Barron, V.; Merghani, K.; Shaw, G.; Coleman, C. M.; Hayes, J. S.; Ansboro, S.; Manian, A.; O’Malley, G.; Connolly, E.; Nandakumar, A.; van Blitterswijk, C. A.; Habibovic, P.; Moroni, L.; Shannon, F.; Murphy, J. M.; Barry, F.

    2015-01-01

    The main objective of this study was to evaluate the effectiveness of a mesenchymal stem cell (MSC)-seeded polyethylene-oxide-terephthalate/polybutylene-terephthalate (PEOT/PBT) scaffold for cartilage tissue repair in an osteochondral defect using a rabbit model. Material characterisation using scan

  5. Repair of osteochondral defects with biodegradable hydrogel composites encapsulating marrow mesenchymal stem cells in a rabbit model.

    NARCIS (Netherlands)

    Guo, X.; Park, H.; Young, S.; Kretlow, J.D.; Beucken, J.J.J.P. van den; Baggett, L.S.; Tabata, Y.; Kasper, F.K.; Mikos, A.G.; Jansen, J.A.

    2010-01-01

    This work investigated the delivery of marrow mesenchymal stem cells (MSCs), with or without the growth factor transforming growth factor-beta1 (TGF-beta1), from biodegradable hydrogel composites on the repair of osteochondral defects in a rabbit model. Three formulations of oligo(poly(ethylene glyc

  6. Molecular constituents of the extracellular matrix in rat liver mounting a hepatic progenitor cell response for tissue repair

    DEFF Research Database (Denmark)

    Vestentoft, Peter Siig; Jelnes, Peter; Andersen, Jesper Bøje

    2013-01-01

    Tissue repair in the adult mammalian liver occurs in two distinct processes, referred to as the first and second tiers of defense. We undertook to characterize the changes in molecular constituents of the extracellular matrix when hepatic progenitor cells (HPCs) respond in a second tier of defense...

  7. Nrf1 CNC-bZIP protein promotes cell survival and nucleotide excision repair through maintaining glutathione homeostasis.

    Science.gov (United States)

    Han, Weinong; Ming, Mei; Zhao, Rui; Pi, Jingbo; Wu, Chunli; He, Yu-Ying

    2012-05-25

    Skin cancer is the most common cancer in the United States. Its major environmental risk factor is UVB radiation in sunlight. In response to UVB damage, epidermal keratinocytes activate a specific repair pathway, i.e. nucleotide excision repair, to remove UVB-induced DNA lesions. However, the regulation of UVB response is not fully understood. Here we show that the long isoform of the nuclear factor erythroid 2-related factor 1 (Nrf1, also called NFE2L1), a cytoprotective transcription factor critical for the expression of multiple antioxidant response element-dependent genes, plays an important role in the response of keratinocytes to UVB. Nrf1 loss sensitized keratinocytes to UVB-induced apoptosis by up-regulating the expression of the proapoptotic Bcl-2 family member Bik through reducing glutathione levels. Knocking down Bik reduced UVB-induced apoptosis in Nrf1-inhibited cells. In UVB-irradiated surviving cells, however, disruption of Nrf1 impaired nucleotide excision repair through suppressing the transcription of xeroderma pigmentosum C (XPC), a factor essential for initiating the global genome nucleotide excision repair by recognizing the DNA lesion and recruiting downstream factors. Nrf1 enhanced XPC expression by increasing glutathione availability but was independent of the transcription repressor of XPC. Adding XPC or glutathione restored the DNA repair capacity in Nrf1-inhibited cells. Finally, we demonstrate that Nrf1 levels are significantly reduced by UVB radiation in mouse skin and are lower in human skin tumors than in normal skin. These results indicate a novel role of Nrf1 in UVB-induced DNA damage repair and suggest Nrf1 as a tumor suppressor in the skin.

  8. DNA Repair Domain Modeling Can Predict Cell Death and Mutation Frequency for Wide Range Spectrum of Radiation

    Science.gov (United States)

    Viger, Louise; Ponomarev, Artem L.; Plante, Ianik; Evain, Trevor; Penninckx, Sebastien; Blattnig, Steve R.; Costes, Sylvain V.

    2017-01-01

    Exploration missions to Mars and other destinations raise many questions about the health of astronauts. The continuous exposure of astronauts to galactic cosmic rays is one of the main concerns for long-term missions. Cosmic ionizing radiations are composed of different ions of various charges and energies notably, highly charged energy (HZE) particles. The HZE particles have been shown to be more carcinogenic than low-LET radiation, suggesting the severity of chromosomal aberrations induced by HZE particles is one possible explanation. However, most mathematical models predicting cell death and mutation frequency are based on directly fitting various HZE dose response and are in essence empirical approaches. In this work, we assume a simple biological mechanism to model DNA repair and use it to simultaneously explain the low- and high-LET response using the exact same fitting parameters. Our work shows that the geometrical position of DNA repair along tracks of heavy ions are sufficient to explain why high-LET particles can induce more death and mutations. Our model is based on assuming DNA double strand breaks (DSBs) are repaired within repair domain, and that any DSBs located within the same repair domain cluster into one repair unit, facilitating chromosomal rearrangements and increasing the probability of cell death. We introduced this model in 2014 using simplified microdosimetry profiles to predict cell death. In this work, we collaborated with NASA Johnson Space Center to generate more accurate microdosimetry profiles derived by Monte Carlo techniques, taking into account track structure of HZE particles and simulating DSBs in realistic cell geometry. We simulated 224 data points (D, A, Z, E) with the BDSTRACKS model, leading to a large coverage of LET from 10 to 2,400 keV/µm. This model was used to generate theoretical RBE for various particles and energies for both cell death and mutation frequencies. The RBE LET dependence is in agreement with

  9. Aryl Hydrocarbon Receptor Activation in Hematopoietic Stem/Progenitor Cells Alters Cell Function and Pathway-Specific Gene Modulation Reflecting Changes in Cellular Trafficking and MigrationS⃞

    OpenAIRE

    Casado, Fanny L.; Singh, Kameshwar P.; Gasiewicz, Thomas A.

    2011-01-01

    The aryl hydrocarbon receptor (AhR) is a transcription factor belonging to the Per-ARNT-Sim family of proteins. These proteins sense molecules and stimuli from the cellular/tissue environment and initiate signaling cascades to elicit appropriate cellular responses. Recent literature reports suggest an important function of AhR in hematopoietic stem cell (HSC) biology. However, the molecular mechanisms by which AhR signaling regulates HSC functions are unknown. In previous studies, we and othe...

  10. Optimality in DNA repair.

    Science.gov (United States)

    Richard, Morgiane; Fryett, Matthew; Miller, Samantha; Booth, Ian; Grebogi, Celso; Moura, Alessandro

    2012-01-07

    DNA within cells is subject to damage from various sources. Organisms have evolved a number of mechanisms to repair DNA damage. The activity of repair enzymes carries its own risk, however, because the repair of two nearby lesions may lead to the breakup of DNA and result in cell death. We propose a mathematical theory of the damage and repair process in the important scenario where lesions are caused in bursts. We use this model to show that there is an optimum level of repair enzymes within cells which optimises the cell's response to damage. This optimal level is explained as the best trade-off between fast repair and a low probability of causing double-stranded breaks. We derive our results analytically and test them using stochastic simulations, and compare our predictions with current biological knowledge.

  11. Systemic neutrophil depletion modulates the migration and fate of transplanted human neural stem cells to rescue functional repair.

    Science.gov (United States)

    Nguyen, Hal X; Hooshmand, Mitra J; Saiwai, Hirokazu; Maddox, Jake; Salehi, Arjang; Lakatos, Anita; Nishi, Rebecca; Salazar, Desiree; Uchida, Nobuko; Anderson, Aileen J

    2017-08-28

    The interaction of transplanted stem cells with local cellular and molecular cues in the host central nervous system (CNS) microenvironment may affect the potential for repair by therapeutic cell populations. In this regard, spinal cord injury (SCI), Alzheimer's disease, and other neurological injuries and diseases all exhibit dramatic and dynamic changes to the host microenvironment over time. Previously, we reported that delayed transplantation of CNS-derived human neural stem cells (hCNS-SCns) at 9 or 30 days post-SCI (dpi) resulted in extensive donor cell migration, predominantly neuronal and oligodendrocytic donor cell differentiation, and functional locomotor improvements. Here, we report that acute transplantation of hCNS-SCns at 0 dpi resulted in localized astroglial differentiation of donor cells near the lesion epicenter, and failure to produce functional improvement in an all-female immunodeficient mouse model. Critically, specific immunodepletion of neutrophils (polymorphonuclear leukocytes, PMN) blocked hCNS-SCns astroglial differentiation near the lesion epicenter and rescued the capacity of these cells to restore function. These data represent novel evidence that a host immune cell population can block the potential for functional repair derived from a therapeutic donor cell population, and support targeting the inflammatory microenvironment in combination with cell transplantation after SCI.SIGNIFICANCE STATEMENTThe interaction of transplanted cells with local cellular and molecular cues in the host microenvironment is a key variable that may shape the translation of neurotransplantation research to the clinical SCI human population, and few studies have investigated these events. We show that the specific immunodepletion of PMN neutrophils using anti-Ly6G inhibits donor cell astrogliosis and rescues the capacity of a donor cell population to promote locomotor improvement after SCI. Critically, our data demonstrate novel evidence that a specific

  12. Inflammatory and repair pathways induced in human bronchoalveolar lavage cells with ozone inhalation.

    Directory of Open Access Journals (Sweden)

    Pascale Leroy

    Full Text Available Inhalation of ambient levels of ozone causes airway inflammation and epithelial injury.To examine the responses of airway cells to ozone-induced oxidative injury, 19 subjects (7 with asthma were exposed to clean air (0ppb, medium (100ppb, and high (200ppb ambient levels of ozone for 4h on three separate occasions in a climate-controlled chamber followed by bronchoscopy with bronchoalveolar lavage (BAL 24h later. BAL cell mRNA expression was examined using Affymetrix GeneChip Microarray. The role of a differentially expressed gene (DEG in epithelial injury was evaluated in an in vitro model of injury [16HBE14o- cell line scratch assay].Ozone exposure caused a dose-dependent up-regulation of several biologic pathways involved in inflammation and repair including chemokine and cytokine secretion, activity, and receptor binding; metalloproteinase and endopeptidase activity; adhesion, locomotion, and migration; and cell growth and tumorigenesis regulation. Asthmatic subjects had 1.7- to 3.8-fold higher expression of many DEGs suggestive of increased proinflammatory and matrix degradation and remodeling signals. The most highly up-regulated gene was osteopontin, the protein level of which in BAL fluid increased in a dose-dependent manner after ozone exposure. Asthmatic subjects had a disproportionate increase in non-polymerized osteopontin with increasing exposure to ozone. Treatment with polymeric, but not monomeric, osteopontin enhanced the migration of epithelial cells and wound closure in an α9β1 integrin-dependent manner.Expression profiling of BAL cells after ozone exposure reveals potential regulatory genes and pathways activated by oxidative stress. One DEG, osteopontin, promotes epithelial wound healing in an in vitro model of injury.

  13. Regenerative repair of damaged meniscus with autologous adipose tissue-derived stem cells.

    Science.gov (United States)

    Pak, Jaewoo; Lee, Jung Hun; Lee, Sang Hee

    2014-01-01

    Mesenchymal stem cells (MSCs) are defined as pluripotent cells found in numerous human tissues, including bone marrow and adipose tissue. Such MSCs, isolated from bone marrow and adipose tissue, have been shown to differentiate into bone and cartilage, along with other types of tissues. Therefore, MSCs represent a promising new therapy in regenerative medicine. The initial treatment of meniscus tear of the knee is managed conservatively with nonsteroidal anti-inflammatory drugs and physical therapy. When such conservative treatment fails, an arthroscopic resection of the meniscus is necessary. However, the major drawback of the meniscectomy is an early onset of osteoarthritis. Therefore, an effective and noninvasive treatment for patients with continuous knee pain due to damaged meniscus has been sought. Here, we present a review, highlighting the possible regenerative mechanisms of damaged meniscus with MSCs (especially adipose tissue-derived stem cells (ASCs)), along with a case of successful repair of torn meniscus with significant reduction of knee pain by percutaneous injection of autologous ASCs into an adult human knee.

  14. Titanium dioxide nanoparticles exhibit genotoxicity and impair DNA repair activity in A549 cells.

    Science.gov (United States)

    Jugan, Mary-Line; Barillet, Sabrina; Simon-Deckers, Angelique; Herlin-Boime, Nathalie; Sauvaigo, Sylvie; Douki, Thierry; Carriere, Marie

    2012-08-01

    Titanium dioxide nanoparticles (TiO(2)-NPs) are produced in large quantities, raising concerns about their impact for human health. The aim of this study was to deeply characterize TiO(2)-NPs genotoxic potential to lung cells, and to link genotoxicity to physicochemical characteristics, e.g., size, specific surface area, crystalline phase. A549 cells were exposed to a panel of TiO(2)-NPs with diameters ranging from 12 to 140 nm, either anatase or rutile. A set of complementary techniques (comet and micronucleus assays, gamma-H2AX immunostaining, 8-oxoGuanine analysis, H2-DCFDA, glutathione content, antioxidant enzymes activities) allowed us to demonstrate that small and spherical TiO(2)-NPs, both anatase and rutile, induce single-strand breaks and oxidative lesions to DNA, together with a general oxidative stress. Additionally we show that these NPs impair cell ability to repair DNA, by inactivation of both NER and BER pathways. This study thus confirms the genotoxic potential of TiO(2)-NPs, which may preclude their mutagenicity and carcinogenicity.

  15. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography.

    Science.gov (United States)

    Thompson, Larry H

    2012-01-01

    The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.

  16. Evaluation of radioinduced damage and repair capacity in human breast cancer cells, MCDF-7 and T4-D

    Energy Technology Data Exchange (ETDEWEB)

    Valgode, F.G.S.; Soares, C.R.J.; Bartolini, P.; Okazaki, K. [Instituto de Pesquisas Energeticas e Nucleares IPEN/CNEN-SP, Sao Paulo, SP (Brazil)]. E-mail: kokazaki@ipen.br

    2007-07-01

    Ionizing radiation is an established etiologic agent for breast cancer, but on the other hand it is a therapeutic modality used in cancer treatment. Accumulation of DNA damage and deficient DNA repair are considered as factors of susceptibility that predispose individuals to breast cancer development. In the present study, genetic damage induced by gamma radiation and repair capacity in the target cells, i.e. cells originating of breast cancer, were analyzed using micronucleus test and comet assay (single-cell alkaline gel electrophoresis). So, two breast tumor cell line, MCF-7 and T-47D were irradiated in a {sup 60}Co source (0.722 Gy/min) with various doses (0.5; 1.0; 2.0; 4.0 and 5.0 Gy). Cytogenetic data showed similar spontaneous damage of two cell lines, the radioinduced damage, however, was higher in T-47D, starting from 2 Gy, with a more accelerated proliferation rate than MCF- 7 at all doses analyzed. Both tumor cell lines were capable to repair a considerable part of radioinduced damage within 1 hour after exposure, indicating a relative radioresistance of theses cell lines to the genotoxic action of ionizing radiation. (author)

  17. More Than Tiny Sacks: Stem Cell Exosomes as Cell-Free Modality for Cardiac Repair.

    Science.gov (United States)

    Kishore, Raj; Khan, Mohsin

    2016-01-22

    Stem cell therapy provides immense hope for regenerating the pathological heart, yet has been marred by issues surrounding the effectiveness, unclear mechanisms, and survival of the donated cell population in the ischemic myocardial milieu. Poor survival and engraftment coupled to inadequate cardiac commitment of the adoptively transferred stem cells compromises the improvement in cardiac function. Various alternative approaches to enhance the efficacy of stem cell therapies and to overcome issues with cell therapy have been used with varied success. Cell-free components, such as exosomes enriched in proteins, messenger RNAs, and miRs characteristic of parental stem cells, represent a potential approach for treating cardiovascular diseases. Recently, exosomes from different kinds of stem cells have been effectively used to promote cardiac function in the pathological heart. The aim of this review is to summarize current research efforts on stem cell exosomes, including their potential benefits and limitations to develop a potentially viable therapy for cardiovascular problems.

  18. Importance of the cell cycle phase for the choice of the appropriate DSB repair pathway, for genome stability maintenance: the trans-S double-strand break repair model.

    Science.gov (United States)

    Delacôte, Fabien; Lopez, Bernard S

    2008-01-01

    A DNA double-strand break (DSB) is a highly harmful lesion that can lead to genome rearrangements. Two main pathways compete for DSB repair: homologous recombination (HR) and nonhomologous end-joining (NHEJ). Depending on the cell cycle phase, the choice of one DSB repair pathway over the other will secure genome stability maintenance or in contrast will increase the risk of genetic instability. HR with the sister chromatid is an efficient way to maintain genome stability, for damage occurring at a post-replication stage. However, in G(1) checkpoint-defective cells, DSBs produced in the G(1) phase and not repaired by NHEJ, can progress through S phase and be processed by HR in late S/G(2) phase. We propose the "trans-S DSB repair" model to account for these data. In this situation HR cannot use the sister chromatid (which is also broken at the same locus) and is thus forced to use ectopic homologous sequences dispersed through the genome, increasing the risk of genetic instability. This shows that the two DSB repair pathways can compete through the cell cycle and underlines the importance of the association between the cell cycle checkpoint and the appropriate DNA repair pathway for genome stability maintenance.

  19. Lineage plasticity and cell biology of fibrocartilage and hyaline cartilage: Its significance in cartilage repair and replacement

    Energy Technology Data Exchange (ETDEWEB)

    Freemont, Anthony J. [Regenerative Medicine Research Group, University of Manchester, England (United Kingdom)]. E-mail: Tony.freemont@man.ac.uk; Hoyland, Judith [Regenerative Medicine Research Group, University of Manchester, England (United Kingdom)

    2006-01-15

    Cartilage repair is a major goal of modern tissue engineering. To produce novel engineered implants requires a knowledge of the basic biology of the tissues that are to be replaced or reproduced. Hyaline articular cartilage and meniscal fibrocartilage are two tissues that have excited attention because of the frequency with which they are damaged. A basic strategy is to re-engineer these tissues ex vivo by stimulating stem cells to differentiate into the cells of the mature tissue capable of producing an intact functional matrix. In this brief review, the sources of cells for tissue engineering cartilage and the culture conditions that have promoted differentiation are discussed within the context of natural cartilage repair. In particular, the role of cell density, cytokines, load, matrices and oxygen tension are discussed.

  20. Transplantation of neurotrophin-3-transfected bone marrow mesenchymal stem cells for the repair of spinal cord injur y

    Institute of Scientific and Technical Information of China (English)

    Yuzhen Dong; Libin Yang; Lin Yang; Hongxing Zhao; Chao Zhang; Dapeng Wu

    2014-01-01

    Bone marrow mesenchymal stem cell transplantation has been shown to be therapeutic in the repair of spinal cord injury. However, the low survival rate of transplanted bone marrow mesen-chymal stem cells in vivo remains a problem. Neurotrophin-3 promotes motor neuron survival and it is hypothesized that its transfection can enhance the therapeutic effect. We show that in vitro transfection of neurotrophin-3 gene increases the number of bone marrow mesenchymal stem cells in the region of spinal cord injury. These results indicate that neurotrophin-3 can promote the survival of bone marrow mesenchymal stem cells transplanted into the region of spinal cord injury and potentially enhance the therapeutic effect in the repair of spinal cord injury.

  1. Electrospun Poly(l-lactide)/Poly(ethylene glycol) Scaffolds Seeded with Human Amniotic Mesenchymal Stem Cells for Urethral Epithelium Repair

    Science.gov (United States)

    Lv, Xiaokui; Guo, Qianping; Han, Fengxuan; Chen, Chunyang; Ling, Christopher; Chen, Weiguo; Li, Bin

    2016-01-01

    Tissue engineering-based urethral replacement holds potential for repairing large segmental urethral defects, which remains a great challenge at present. This study aims to explore the potential of combining biodegradable poly(l-lactide) (PLLA)/poly(ethylene glycol) (PEG) scaffolds and human amniotic mesenchymal cells (hAMSCs) for repairing urethral defects. PLLA/PEG fibrous scaffolds with various PEG fractions were fabricated via electrospinning. The scaffolds were then seeded with hAMSCs prior to implantation in New Zealand male rabbits that had 2.0 cm-long defects in the urethras. The rabbits were randomly divided into three groups. In group A, hAMSCs were grown on PLLA/PEG scaffolds for two days and then implanted to the urethral defects. In group B, only the PLLA/PEG scaffolds were used to rebuild the rabbit urethral defect. In group C, the urethral defect was reconstructed using a regular urethral reparation technique. The repair efficacy was compared among the three groups by examining the urethral morphology, tissue reconstruction, luminal patency, and complication incidence (including calculus formation, urinary fistula, and urethral stricture) using histological evaluation and urethral radiography methods. Findings from this study indicate that hAMSCs-loaded PLLA/PEG scaffolds resulted in the best urethral defect repair in rabbits, which predicts the promising application of a tissue engineering approach for urethral repair. PMID:27517902

  2. Electrospun Poly(l-lactide/Poly(ethylene glycol Scaffolds Seeded with Human Amniotic Mesenchymal Stem Cells for Urethral Epithelium Repair

    Directory of Open Access Journals (Sweden)

    Xiaokui Lv

    2016-08-01

    Full Text Available Tissue engineering-based urethral replacement holds potential for repairing large segmental urethral defects, which remains a great challenge at present. This study aims to explore the potential of combining biodegradable poly(l-lactide (PLLA/poly(ethylene glycol (PEG scaffolds and human amniotic mesenchymal cells (hAMSCs for repairing urethral defects. PLLA/PEG fibrous scaffolds with various PEG fractions were fabricated via electrospinning. The scaffolds were then seeded with hAMSCs prior to implantation in New Zealand male rabbits that had 2.0 cm-long defects in the urethras. The rabbits were randomly divided into three groups. In group A, hAMSCs were grown on PLLA/PEG scaffolds for two days and then implanted to the urethral defects. In group B, only the PLLA/PEG scaffolds were used to rebuild the rabbit urethral defect. In group C, the urethral defect was reconstructed using a regular urethral reparation technique. The repair efficacy was compared among the three groups by examining the urethral morphology, tissue reconstruction, luminal patency, and complication incidence (including calculus formation, urinary fistula, and urethral stricture using histological evaluation and urethral radiography methods. Findings from this study indicate that hAMSCs-loaded PLLA/PEG scaffolds resulted in the best urethral defect repair in rabbits, which predicts the promising application of a tissue engineering approach for urethral repair.

  3. Electrospun Poly(l-lactide)/Poly(ethylene glycol) Scaffolds Seeded with Human Amniotic Mesenchymal Stem Cells for Urethral Epithelium Repair.

    Science.gov (United States)

    Lv, Xiaokui; Guo, Qianping; Han, Fengxuan; Chen, Chunyang; Ling, Christopher; Chen, Weiguo; Li, Bin

    2016-08-09

    Tissue engineering-based urethral replacement holds potential for repairing large segmental urethral defects, which remains a great challenge at present. This study aims to explore the potential of combining biodegradable poly(l-lactide) (PLLA)/poly(ethylene glycol) (PEG) scaffolds and human amniotic mesenchymal cells (hAMSCs) for repairing urethral defects. PLLA/PEG fibrous scaffolds with various PEG fractions were fabricated via electrospinning. The scaffolds were then seeded with hAMSCs prior to implantation in New Zealand male rabbits that had 2.0 cm-long defects in the urethras. The rabbits were randomly divided into three groups. In group A, hAMSCs were grown on PLLA/PEG scaffolds for two days and then implanted to the urethral defects. In group B, only the PLLA/PEG scaffolds were used to rebuild the rabbit urethral defect. In group C, the urethral defect was reconstructed using a regular urethral reparation technique. The repair efficacy was compared among the three groups by examining the urethral morphology, tissue reconstruction, luminal patency, and complication incidence (including calculus formation, urinary fistula, and urethral stricture) using histological evaluation and urethral radiography methods. Findings from this study indicate that hAMSCs-loaded PLLA/PEG scaffolds resulted in the best urethral defect repair in rabbits, which predicts the promising application of a tissue engineering approach for urethral repair.

  4. Hippocampal Adult Neurogenesis Is Maintained by Neil3-Dependent Repair of Oxidative DNA Lesions in Neural Progenitor Cells

    Directory of Open Access Journals (Sweden)

    Christine Elisabeth Regnell

    2012-09-01

    Full Text Available Accumulation of oxidative DNA damage has been proposed as a potential cause of age-related cognitive decline. The major pathway for removal of oxidative DNA base lesions is base excision repair, which is initiated by DNA glycosylases. In mice, Neil3 is the main DNA glycosylase for repair of hydantoin lesions in single-stranded DNA of neural stem/progenitor cells, promoting neurogenesis. Adult neurogenesis is crucial for maintenance of hippocampus-dependent functions involved in behavior. Herein, behavioral studies reveal learning and memory deficits and reduced anxiety-like behavior in Neil3−/− mice. Neural stem/progenitor cells from aged Neil3−/− mice show impaired proliferative capacity and reduced DNA repair activity. Furthermore, hippocampal neurons in Neil3−/− mice display synaptic irregularities. It appears that Neil3-dependent repair of oxidative DNA damage in neural stem/progenitor cells is required for maintenance of adult neurogenesis to counteract the age-associated deterioration of cognitive performance.

  5. Cadmium sulfate and CdTe-quantum dots alter DNA repair in zebrafish (Danio rerio) liver cells

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Song; Cai, Qingsong [The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416 (United States); Chibli, Hicham [Department of Biomedical Engineering, McGill University, Montréal, QC H3A 2B4 (Canada); Allagadda, Vinay [The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416 (United States); Nadeau, Jay L. [Department of Biomedical Engineering, McGill University, Montréal, QC H3A 2B4 (Canada); Mayer, Gregory D., E-mail: greg.mayer@ttu.edu [The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416 (United States)

    2013-10-15

    Increasing use of quantum dots (QDs) makes it necessary to evaluate their toxicological impacts on aquatic organisms, since their contamination of surface water is inevitable. This study compares the genotoxic effects of ionic Cd versus CdTe nanocrystals in zebrafish hepatocytes. After 24 h of CdSO{sub 4} or CdTe QD exposure, zebrafish liver (ZFL) cells showed a decreased number of viable cells, an accumulation of Cd, an increased formation of reactive oxygen species (ROS), and an induction of DNA strand breaks. Measured levels of stress defense and DNA repair genes were elevated in both cases. However, removal of bulky DNA adducts by nucleotide excision repair (NER) was inhibited with CdSO{sub 4} but not with CdTe QDs. The adverse effects caused by acute exposure of CdTe QDs might be mediated through differing mechanisms than those resulting from ionic cadmium toxicity, and studying the effects of metallic components may be not enough to explain QD toxicities in aquatic organisms. - Highlights: • Both CdSO{sub 4} and CdTe QDs lead to cell death and Cd accumulation. • Both CdSO{sub 4} and CdTe QDs induce cellular ROS generation and DNA strand breaks. • Both CdSO{sub 4} and CdTe QDs induce the expressions of stress defense and DNA repair genes. • NER repair capacity was inhibited with CdSO{sub 4} but not with CdTe QDs.

  6. Enhancement of the genotoxicity of benzo[a]pyrene by arecoline through suppression of DNA repair in HEp-2 cells.

    Science.gov (United States)

    Huang, J L; Lu, H H; Lu, Y N; Hung, P S; Lin, Y J; Lin, C C; Yang, C C; Wong, T Y; Lu, S Y; Lin, C S

    2016-06-01

    The International Agency for Research on Cancer lists the principal component of betel quid (BQ), the areca nut, and that of cigarette smoke, benzo[a]pyrene (BaP), as Group 1 carcinogens. Epidemiological studies have shown that coexposure of BQ and cigarette smoke markedly increases the risk of cancer. We previously demonstrated that arecoline, the most abundant alkaloid in the areca nut, inhibits nucleotide excision repair through the repression of p53 activity. To investigate the combined potency of arecoline and BaP in carcinogenesis, we treated human epithelial HEp-2 cells with subcytotoxic doses of arecoline and BaP, alone or in combination, and examined the effects on DNA damage and repair. When exposed for 24h, BaP enhanced DNA repair and p53 transactivation activity. However, these enhancements were suppressed through concurrent treatment of the cells with arecoline. Using a Comet assay, we found that extended exposure to arecoline and BaP caused moderate-to-severe DNA damage in 60% of the cells. Expression of the XPD helicase was transcriptionally suppressed by 1 week of treatment with BaP. Our studies have revealed potential targets in the DNA repair pathway that are affected by BQ and tobacco components, as well as the effect of these components on carcinogenesis. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Adipose tissue-derived mesenchymal stem cells repair germinal cells of seminiferous tubules of busulfan-induced azoospermic rats

    Directory of Open Access Journals (Sweden)

    Davood Mehrabani

    2015-01-01

    Full Text Available Context: Adipose tissue-derived mesenchymal stem cells (AT-MSCs are less invasive than bone marrow mesenchymal stem cells to obtain for cell therapy. Aims: The aims of this study were to evaluate the germinal cells characteristics and repairs in seminiferous tubules of busulfan-induced azoospermic rats after AT-MSCs transplantation. Settings and Design: Experimental case-control study. Materials and Methods: In the present experimental study, donors AT-MSCs were isolated from subcutaneous adipose tissue of two Sprague-Dawley rats. The recipients (n = 5 were received two doses of 10 mg/kg of busulfan with 21 days interval to stop endogenous spermatogenesis. After induction of azoospermia by busulfan, rats were injected with the AT-MSCs into the efferent duct of right testes. After 60 days, the right testes were injected AT-MSCs were compared to left azoospermic testes. Five untreated male rats served as negative control. Statistical Analysis Used: Stereological indices were analyzed by one-way ANOVA and LSD post-hoc test. The spermatogenesis index was compared using Mann-Whitney U test. Results: After stereological analyses, the seminiferous tubules treated with AT-MSCs had normal morphology. The untreated seminiferous tubules were empty. Spermatogenesis was observed in most cell-treated seminiferous tubules. Conclusions: The testis of busulfan-induced azoospermic rats accepted transplanted AT-MSCs. The transplanted AT-MSCs could induce spermatogenesis in seminiferous tubules of the rat.

  8. Resident adult neural stem cells in Parkinson's disease--the brain's own repair system?

    Science.gov (United States)

    van den Berge, Simone A; van Strien, Miriam E; Hol, Elly M

    2013-11-05

    One important pathological process in the brain of Parkinson disease (PD) patients is the degeneration of the dopaminergic neurons in the substantia nigra, which leads to a decline in striatal dopamine levels and motor dysfunction. A major clinical problem is that this degenerative process currently cannot be stopped or reversed. Expectations from the restorative capacity of neural stem cells (NSCs) are high, as these cells can potentially replace the degenerating neurons. The discovery of the presence of NSCs in the adult human brain has instigated research into the potential of these cells as a resource to promote brain repair in neurodegenerative diseases. Neural stem and progenitor cells reside in the subventricular zone (SVZ), which is closely situated to the striatum, which is affected in PD. Therefore, restoring the dopamine levels in the striatum of PD patients through stimulating endogenous NSCs in the nearby SVZ to migrate into the striatum and differentiate into dopaminergic neurons might thus be an attractive future therapeutic approach. We will review the reported changes in NSCs in the SVZ of PD animal models and PD patients, which are due to a lack of striatal dopamine. Furthermore, we will summarise the reports that describe efforts to stimulate NSCs to replace dopaminergic cells in the SN and restore striatal dopamine levels. In our opinion, mobilizing the endogenous SVZ NSCs to replenish striatal dopamine is an attractive approach to alleviate the motor symptoms in PD patients, without the ethical and immunological challenges of transplantation of NSCs and foetal brain tissue. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Repair of traumatic plasmalemmal damage to neurons and other eukar yotic cells

    Institute of Scientific and Technical Information of China (English)

    George D. Bittner; Christopher S. Spaeth§; Andrew D. Poon; Zachary S. Burgess; Christopher H. McGill

    2016-01-01

    The repair (sealing) of plasmalemmal damage, consisting of small holes to complete transections, is criti-cal for cell survival, especially for neurons that rarely regenerate cell bodies. We ifrst describe and evaluate different measures of cell sealing. Some measures, including morphological/ultra-structural observations, membrane potential, and input resistance, provide very ambiguous assessments of plasmalemmal sealing. In contrast, measures of ionic current lfow and dye barriers can, if appropriately used, provide more ac-curate assessments. We describe the effects of various substances (calcium, calpains, cytoskeletal proteins, ESCRT proteins, mUNC-13, NSF, PEG) and biochemical pathways (PKA, PKC, PLC, Epac, cytosolic ox-idation) on plasmalemmal sealing probability, and suggest that substances, pathways, and cellular events associated with plasmalemmal sealing have undergone a very conservative evolution. During sealing, calcium ion inlfux mobilizes vesicles and other membranous structures (lysosomes, mitochondria, etc.) in a continuous fashion to form a vesicular plug that gradually restricts diffusion of increasingly smaller molecules and ions over a period of seconds to minutes. Furthermore, we find no direct evidence that sealing occurs through the collapse and fusion of severed plasmalemmal lealfets, or in a single step involv-ing the fusion of one large wound vesicle with the nearby, undamaged plasmalemma. We describe how increases in perikaryal calcium levels following axonal transection account for observations that cell body survival decreases the closer an axon is transected to the perikaryon. Finally, we speculate on relationships between plasmalemmal sealing, Wallerian degeneration, and the ability of polyethylene glycol (PEG) to seal cell membranes and rejoin severed axonal ends–an important consideration for the future treatment of trauma to peripheral nerves. A better knowledge of biochemical pathways and cytoplasmic structures in-volved in

  10. Repair of traumatic plasmalemmal damage to neurons and other eukaryotic cells

    Directory of Open Access Journals (Sweden)

    George D Bittner

    2016-01-01

    Full Text Available The repair (sealing of plasmalemmal damage, consisting of small holes to complete transections, is critical for cell survival, especially for neurons that rarely regenerate cell bodies. We first describe and evaluate different measures of cell sealing. Some measures, including morphological/ultra-structural observations, membrane potential, and input resistance, provide very ambiguous assessments of plasmalemmal sealing. In contrast, measures of ionic current flow and dye barriers can, if appropriately used, provide more accurate assessments. We describe the effects of various substances (calcium, calpains, cytoskeletal proteins, ESCRT proteins, mUNC-13, NSF, PEG and biochemical pathways (PKA, PKC, PLC, Epac, cytosolic oxidation on plasmalemmal sealing probability, and suggest that substances, pathways, and cellular events associated with plasmalemmal sealing have undergone a very conservative evolution. During sealing, calcium ion influx mobilizes vesicles and other membranous structures (lysosomes, mitochondria, etc. in a continuous fashion to form a vesicular plug that gradually restricts diffusion of increasingly smaller molecules and ions over a period of seconds to minutes. Furthermore, we find no direct evidence that sealing occurs through the collapse and fusion of severed plasmalemmal leaflets, or in a single step involving the fusion of one large wound vesicle with the nearby, undamaged plasmalemma. We describe how increases in perikaryal calcium levels following axonal transection account for observations that cell body survival decreases the closer an axon is transected to the perikaryon. Finally, we speculate on relationships between plasmalemmal sealing, Wallerian degeneration, and the ability of polyethylene glycol (PEG to seal cell membranes and rejoin severed axonal ends – an important consideration for the future treatment of trauma to peripheral nerves. A better knowledge of biochemical pathways and cytoplasmic structures

  11. Effect of 2-deoxy-D-glucose on DNA double strand break repair, cell survival and energy metabolism in euoxic Ehrlich ascites tumour cells

    Energy Technology Data Exchange (ETDEWEB)

    Jha, B.; Pohlit, W. (L.N. Mithila Univ., Darbhanga (India). Botany Dept.)

    1992-10-01

    Effects of 2-deoxy-D-glucose (2-DG) on DNA double strand break (dsb) repair, cell survival and on the energy metabolism were investigated in exponentially growing Ehrlich ascites tumour (EAT) cells. Cells in suspension were exposed to 40 Gy of X-rays and allowed to repair (up to 4h) with or without 2-DG at 37[sup o]C. DNA dsb rejoining was measured by means of clamped homogeneous electric field (CHEF), a pulsed field gel electrophoresis technique. The fraction of activity released (FAR) during electrophoresis (DNA associated [sup 14]C-thymidine) was used as a parameter to determine the number of dsb present in the DNA. Biphasic kinetics for dsb repair were observed. The presence of 2-DG significantly inhibited the slow component of dsb repair. The presence of 2-DG also enhanced radiation-induced cell killing. ATP content of cells was measured by a bioluminescence method. ATP content in exponentially growing cells was about 4 pg per cell. The level of ATP was reduced by 50% in presence of 2-DG (C[sub 2-DG]/C[sub G] = 1.0). (author).

  12. Nucleotide Excision Repair and Transcription-coupled DNA Repair Abrogate the Impact of DNA Damage on Transcription.

    Science.gov (United States)

    Nadkarni, Aditi; Burns, John A; Gandolfi, Alberto; Chowdhury, Moinuddin A; Cartularo, Laura; Berens, Christian; Geacintov, Nicholas E; Scicchitano, David A

    2016-01-01

    DNA adducts derived from carcinogenic polycyclic aromatic hydrocarbons like benzo[a]pyrene (B[a]P) and benzo[c]phenanthrene (B[c]Ph) impede replication and transcription, resulting in aberrant cell division and gene expression. Global nucleotide excision repair (NER) and transcription-coupled DNA repair (TCR) are among the DNA repair pathways that evolved to maintain genome integrity by removing DNA damage. The interplay between global NER and TCR in repairing the polycyclic aromatic hydrocarbon-derived DNA adducts (+)-trans-anti-B[a]P-N(6)-dA, which is subject to NER and blocks transcription in vitro, and (+)-trans-anti-B[c]Ph-N(6)-dA, which is a poor substrate for NER but also blocks transcription in vitro, was tested. The results show that both adducts inhibit transcription in human cells that lack both NER and TCR. The (+)-trans-anti-B[a]P-N(6)-dA lesion exhibited no detectable effect on transcription in cells proficient in NER but lacking TCR, indicating that NER can remove the lesion in the absence of TCR, which is consistent with in vitro data. In primary human cells lacking NER, (+)-trans-anti-B[a]P-N(6)-dA exhibited a deleterious effect on transcription that was less severe than in cells lacking both pathways, suggesting that TCR can repair the adduct but not as effectively as global NER. In contrast, (+)-trans-anti-B[c]Ph-N(6)-dA dramatically reduces transcript production in cells proficient in global NER but lacking TCR, indicating that TCR is necessary for the removal of this adduct, which is consistent with in vitro data showing that it is a poor substrate for NER. Hence, both global NER and TCR enhance the recovery of gene expression following DNA damage, and TCR plays an important role in removing DNA damage that is refractory to NER.

  13. Defining a role for non-satellite stem cells in the regulation of muscle repair following exercise

    Directory of Open Access Journals (Sweden)

    Marni D. Boppart

    2013-11-01

    Full Text Available Skeletal muscle repair is essential for effective remodeling, tissue maintenance, and initiation of beneficial adaptations post-eccentric exercise. A series of well characterized events, such as recruitment of immune cells and activation of satellite cells, constitute the basis for muscle regeneration. However, details regarding the fine-tuned regulation of this process in response to different types of injury are open for investigation. Muscle-resident non-myogenic, non-satellite stem cells expressing conventional mesenchymal stem cell (MSC markers, have the potential to significantly contribute to regeneration given the role for bone marrow-derived MSCs in whole body tissue repair in response to injury and disease. The purpose of this mini-review is to highlight a regulatory role for non-satellite stem cells in the process of skeletal muscle healing post-eccentric exercise. The non-myogenic, non-satellite stem cell fraction will be defined, its role in tissue repair will be briefly reviewed, and recent studies demonstrating a contribution to eccentric exercise-induced regeneration will be presented.  

  14. Generation of human secondary cardiospheres as a potent cell processing strategy for cell-based cardiac repair.

    Science.gov (United States)

    Cho, Hyun-Jai; Lee, Ho-Jae; Chung, Yeon-Ju; Kim, Ju-Young; Cho, Hyun-Ju; Yang, Han-Mo; Kwon, Yoo-Wook; Lee, Hae-Young; Oh, Byung-Hee; Park, Young-Bae; Kim, Hyo-Soo

    2013-01-01

    Cell therapy is a promising approach for repairing damaged heart. However, there are large rooms to be improved in therapeutic efficacy. We cultured a small quantity (5-10 mg) of heart biopsy tissues from 16 patients who received heart transplantation. We produced primary and secondary cardiospheres (CSs) using repeated three-dimensional culture strategy and characterized the cells. Approximately 5000 secondary CSs were acquired after 45 days. Genetic analysis confirmed that the progenitor cells in the secondary CSs originated from the innate heart, but not from extra-cardiac organs. The expressions of Oct4 and Nanog were significantly induced in secondary CSs compared with adherent cells derived from primary CSs. Those expressions in secondary CSs were higher in a cytokine-deprived medium than in a cytokine-supplemented one, suggesting that formation of the three-dimensional structure was important to enhance stemness whereas supplementation with various cytokines was not essential. Signal blocking experiments showed that the ERK and VEGF pathways are indispensable for sphere formation. To optimize cell processing, we compared four different methods of generating spheres. Method based on the hanging-drop or AggreWell™ was superior to that based on the poly-d-lysine-coated dish or Petri dish with respect to homogeneity of the product, cellular potency and overall simplicity of the process. When transplanted into the ischemic myocardium of immunocompromised mice, human secondary CSs differentiated into cardiomyocytes and endothelial cells. These results demonstrate that generation of secondary CSs from a small quantity of adult human cardiac tissue is a feasible and effective cell processing strategy to improve the therapeutic efficacy of cell therapy.

  15. Aryl hydrocarbon receptor nuclear translocator (ARNT) isoforms control lymphoid cancer cell proliferation through differentially regulating tumor suppressor p53 activity.

    Science.gov (United States)

    Gardella, Kacie A; Muro, Israel; Fang, Gloria; Sarkar, Krishnakali; Mendez, Omayra; Wright, Casey W

    2016-03-01

    The aryl hydrocarbon receptor nuclear translocator (ARNT) is involved in xenobiotic and hypoxic responses, and we previously showed that ARNT also regulates nuclear factor-κB (NF-κB) signaling by altering the DNA binding activity of the RelB subunit. However, our initial study of ARNT-mediated RelB modulation was based on simultaneous suppression of the two ARNT isoforms, isoform 1 and 3, and precluded the examination of their individual functions. We find here that while normal lymphocytes harbor equal levels of isoform 1 and 3, lymphoid malignancies exhibit a shift to higher levels of ARNT isoform 1. These elevated levels of ARNT isoform 1 are critical to the proliferation of these cancerous cells, as suppression of isoform 1 in a human multiple myeloma (MM) cell line, and an anaplastic large cell lymphoma (ALCL) cell line, triggered S-phase cell cycle arrest, spontaneous apoptosis, and sensitized cells to doxorubicin treatment. Furthermore, co-suppression of RelB or p53 with ARNT isoform 1 prevented cell cycle arrest and blocked doxorubicin induced apoptosis. Together our findings reveal that certain blood cancers rely on ARNT isoform 1 to potentiate proliferation by antagonizing RelB and p53-dependent cell cycle arrest and apoptosis. Significantly, our results identify ARNT isoform 1 as a potential target for anticancer therapies.

  16. Recombination-dependent deletion formation in mammalian cells deficient in the nucleotide excision repair gene ERCC1.

    Science.gov (United States)

    Sargent, R G; Rolig, R L; Kilburn, A E; Adair, G M; Wilson, J H; Nairn, R S

    1997-11-25

    Nucleotide excision repair proteins have been implicated in genetic recombination by experiments in Saccharomyces cerevisiae and Drosophila melanogaster, but their role, if any, in mammalian cells is undefined. To investigate the role of the nucleotide excision repair gene ERCC1, the hamster homologue to the S. cerevisiae RADIO gene, we disabled the gene by targeted knockout. Partial tandem duplications of the adenine phosphoribosyltransferase (APRT) gene then were constructed at the endogenous APRT locus in ERCC1- and ERCC1+ cells. To detect the full spectrum of gene-altering events, we used a loss-of-function assay in which the parental APRT+ tandem duplication could give rise to APRT- cells by homologous recombination, gene rearrangement, or point mutation. Measurement of rates and analysis of individual APRT- products indicated that gene rearrangements (principally deletions) were increased at least 50-fold, whereas homologous recombination was affected little. The formation of deletions is not caused by a general effect of the ERCC1 deficiency on gene stability, because ERCC1- cell lines with a single wild-type copy of the APRT gene yielded no increase in deletions. Thus, deletion formation is dependent on the tandem duplication, and presumably the process of homologous recombination. Recombination-dependent deletion formation in ERCC1- cells is supported by a significant decrease in a particular class of crossover products that are thought to arise by repair of a heteroduplex intermediate in recombination. We suggest that the ERCC1 gene product in mammalian cells is involved in the processing of heteroduplex intermediates in recombination and that the misprocessed intermediates in ERCC1- cells are repaired by illegitimate recombination.

  17. Breast cancer stem-like cells are inhibited by a non-toxic aryl hydrocarbon receptor agonist.

    Directory of Open Access Journals (Sweden)

    Gérald J Prud'homme

    Full Text Available BACKGROUND: Cancer stem cells (CSCs have increased resistance to cancer chemotherapy. They can be enriched as drug-surviving CSCs (D-CSCs by growth with chemotherapeutic drugs, and/or by sorting of cells expressing CSC markers such as aldehyde dehydrogenase-1 (ALDH. CSCs form colonies in agar, mammospheres in low-adherence cultures, and tumors following xenotransplantation in Scid mice. We hypothesized that tranilast, a non-toxic orally active drug with anti-cancer activities, would inhibit breast CSCs. METHODOLOGY/FINDINGS: We examined breast cancer cell lines or D-CSCs generated by growth of these cells with mitoxantrone. Tranilast inhibited colony formation, mammosphere formation and stem cell marker expression. Mitoxantrone-selected cells were enriched for CSCs expressing stem cell markers ALDH, c-kit, Oct-4, and ABCG2, and efficient at forming mammospheres. Tranilast markedly inhibited mammosphere formation by D-CSCs and dissociated formed mammospheres, at pharmacologically relevant concentrations. It was effective against D-CSCs of both HER-2+ and triple-negative cell lines. Tranilast was also effective in vivo, since it prevented lung metastasis in mice injected i.v. with triple-negative (MDA-MB-231 mitoxantrone-selected cells. The molecular targets of tranilast in cancer have been unknown, but here we demonstrate it is an aryl hydrocarbon receptor (AHR agonist and this plays a key role. AHR is a transcription factor activated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, polycyclic aromatic hydrocarbons and other ligands. Tranilast induced translocation of the AHR to the nucleus and stimulated CYP1A1 expression (a marker of AHR activation. It inhibited binding of the AHR to CDK4, which has been linked to cell-cycle arrest. D-CSCs expressed higher levels of the AHR than other cells. Knockdown of the AHR with siRNA, or blockade with an AHR antagonist, entirely abrogated the anti-proliferative and anti-mammosphere activity of tranilast

  18. Cell and protein compatible 3D bioprinting of mechanically strong constructs for bone repair.

    Science.gov (United States)

    Sawkins, M J; Mistry, P; Brown, B N; Shakesheff, K M; Bonassar, L J; Yang, J

    2015-07-02

    Rapid prototyping of bone tissue engineering constructs often utilizes elevated temperatures, organic solvents and/or UV light for materials processing. These harsh conditions may prevent the incorporation of cells and therapeutic proteins in the fabrication processes. Here we developed a method for using bioprinting to produce constructs from a thermoresponsive microparticulate material based on poly(lactic-co-glycolic acid) at ambient conditions. These constructs could be engineered with yield stresses of up to 1.22 MPa and Young's moduli of up to 57.3 MPa which are within the range of properties of human cancellous bone. Further study showed that protein-releasing microspheres could be incorporated into the bioprinted constructs. The release of the model protein lysozyme from bioprinted constructs was sustainted for a period of 15 days and a high degree of protein activity could be measured up to day 9. This work suggests that bioprinting is a viable route to the production of mechanically strong constructs for bone repair under mild conditions which allow the inclusion of viable cells and active proteins.

  19. Cell and gene therapy for arrhythmias: Repair of cardiac conduction damage

    Institute of Scientific and Technical Information of China (English)

    Yong-Fu Xiao

    2011-01-01

    Action potentials generated in the sinoatrial node(SAN)dominate the rhythm and rate of a healthy human heart.Subsequently,these action potentials propagate to the whole heart via its conduction system .Abnormalities of impulse generation and/or propagation in a heart can cause arrhythmias.For example,SAN dysfunction or conduction block of the atrioventricular node can lead to serious bradycardia which is currently treated with an implanted electronic pacemaker.On the other hand conduction damage may cause reentrant tachyarrhythmias which are primarily treated pharmacologically or by medical device-based therapies,including defibrillation and tissue ablation.However,drug therapies sometimes may not be effective or are associated with serious side effects.Device-based therapies for cardiac arrhythmias,even with well developed technology,still face inadequacies,limitations,hardware complications,and other challenges.Therefore,scientists are actively seeking other alternatives for antiarrhythmic therapy.In particular,cells and genes used for repairing cardiac conduction damage/defect have been investigated in various studies both in vitro and in vivo.Despite the complexities of the excitation and conduction systems of the heart,cell and gene-based strategies provide novel alternatives for treatment or cure of cardiac anhythmias.This review summarizes some highlights of recent research progress in this field.

  20. A human esophageal epithelial cell model for study of radiation induced cancer and DNA repair

    Science.gov (United States)

    Huff, Janice; Patel, Zarana; Hada, Megumi; Cucinotta, Francis A.

    For cancer risk assessment in astronauts and for countermeasure development, it is essential to understand the molecular mechanisms of radiation carcinogenesis and how these mechanisms are influenced by exposure to the types of radiation found in space. We are developing an in vitro model system for the study of radiation-induced initiation and progression of esophageal carcinoma. Development of squamous cell carcinoma of the esophagus is associated with radiation exposure, as revealed by the significant enhanced in incidence rates for this type of cancer in the survivors of the atomic bomb detonations in Japan. It is also associated with poor nutritional status and micronutrient deficiencies, which are also important issues for long duration spaceflight. The possible synergies between nutritional issues and radiation exposure are unknown. Here we present the results of preliminary characterization of both normal and hTERT-immortalized esophageal epithelial cells grown in 2-dimensional culture. We analyzed DNA repair capacity by measuring the kinetics of formation and loss of gamma-H2AX foci following radiation exposure. Additionally, we analyzed induction of chromosomal aberrations using 3-color fluorescence in situ hybridization (FISH). Data were generated using both low LET (gamma rays) and high LET ions (1000 MeV/nucleon iron.

  1. The role of biologically active peptides in tissue repair using umbilical cord mesenchymal stem cells.

    Science.gov (United States)

    Cabrera, Carlos; Carriquiry, Gabriela; Pierinelli, Chiara; Reinoso, Nancy; Arias-Stella, Javier; Paino, Javier

    2012-10-01

    The role of bioactive compounds in wound repair is critical. The preliminary work described herein includes the study of the effects of second degree burns in a Rex rabbit model and the action of human umbilical cord cells on the regulation and secretion of bioactive compounds. When applied on blood scaffolds as heterograft matrices, fibroblasts proliferate from these primary cultures and release biologically active peptides under tight control. Our work in progress indicates that mesenchymal stem cell (MSC)-mediated therapy provides better quality and more efficient burn reepithelialization of injured tissues by controlling the release of these peptides. Improvement of wound aesthetics is achieved in less time than without MSC-mediated therapy. Well-organized epidermal regeneration and overall better quality of reepithelialization, with no rejection, can be demonstrated consistently with periodic biopsies. Our studies indicate that MSCs have the capacity to produce, regulate, and deliver biologically active peptides that result in superior regeneration, compared with conventional treatments. © 2012 New York Academy of Sciences.

  2. Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

    Science.gov (United States)

    Huang, Brian J.; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2016-01-01

    One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of review articles on the paradigm of biomaterials, signals, and cells, it is reported that 90% of new drugs that advance past animal studies fail clinical trials (1). The intent of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by fully understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products. PMID:27177218

  3. AKT-modified autologous intracoronary mesenchymal stem cells prevent remodeling and repair in swine infarcted myocardium

    Institute of Scientific and Technical Information of China (English)

    YU Yun-sheng; SHEN Zhen-ya; YE Wen-xue; HUANG Hao-yue; HUA Fei; CHEN Yi-huan; CHEN Ke; LAO Wei-jie; TAO Li

    2010-01-01

    Background Transplantation of adult bone marrow-derived mesenchymal stem cells (MSCs) has been proposed as a strategy for cardiac repair following myocardial damage. However cell transplantation strategies to replace lost myocardium are limited by the inability to deliver large numbers of cells that resist peritransplantation graft cell death. Accordingly, we set out to isolate and expand adult swine bone marrow-derived MSCs, and to engineer these cells to overexpress AKT1 (protein kinase B), to test the hypothesis that AKT1 -engineered MSCs are more resistant to apoptosis and can enhance cardiac repair after transplantation into the ischemic swine heart.Methods The CDS (regulation domain of AKT1) AKT1-cDNA fragment was amplified, and MSCs were transfected following synthesis with a pCDH1-AKT1 shuttling plasmid. Western blotting analysis and real-time reverse transcription-polymerase chain reaction (RT-PCR) was performed. Myocardial infarction (Ml) models were constructed in Meishan pigs, and cardiac function was evaluated by magnetic resonance imaging (MRI) measurements and echocardiography 4 weeks later. All pigs were assigned to four groups: control (A), DMEM (B), MSC (C), and AKT-transfected (D). MSCs were transfected with the AKT1 gene, and autologous BrdU-labeled stem cells (1 × 107/5 ml) were injected into left anterior descending coronary atery (LAD) of the infarct heart in groups C and D. In group B, DMEM was injected using the same approach. In group A, there was no injection following LAD occlusion. After 4 weeks, cardiac function and regional perfusion measurements were repeated by MRI and echocardiography, and histological characteristics of the hearts were assessed. Connecxin-43 (CX-43), BrdU, and von Willebrand factor (VWF) immunoreactivity was tested using enzyme linked immunosorbent assay (ELISA). Vascular endothelial growth factor (VEGF), transforming growth factor-(31 (TGF-p1) were analyzed at the same time.Results AKT1-cDNA was cloned into p

  4. Stem cells in the hair follicle bulge contribute to wound repair but not to homeostasis of the epidermis.

    Science.gov (United States)

    Ito, Mayumi; Liu, Yaping; Yang, Zaixin; Nguyen, Jane; Liang, Fan; Morris, Rebecca J; Cotsarelis, George

    2005-12-01

    The discovery of long-lived epithelial stem cells in the bulge region of the hair follicle led to the hypothesis that epidermal renewal and epidermal repair after wounding both depend on these cells. To determine whether bulge cells are necessary for epidermal renewal, here we have ablated these cells by targeting them with a suicide gene encoding herpes simplex virus thymidine kinase (HSV-TK) using a Keratin 1-15 (Krt1-15) promoter. We show that ablation leads to complete loss of hair follicles but survival of the epidermis. Through fate-mapping experiments, we find that stem cells in the hair follicle bulge do not normally contribute cells to the epidermis which is organized into epidermal proliferative units, as previously predicted. After epidermal injury, however, cells from the bulge are recruited into the epidermis and migrate in a linear manner toward the center of the wound, ultimately forming a marked radial pattern. Notably, although the bulge-derived cells acquire an epidermal phenotype, most are eliminated from the epidermis over several weeks, indicating that bulge stem cells respond rapidly to epidermal wounding by generating short-lived 'transient amplifying' cells responsible for acute wound repair. Our findings have implications for both gene therapy and developing treatments for wounds because it will be necessary to consider epidermal and hair follicle stem cells as distinct populations.

  5. Regulation of DNA repair mechanism in human glioma xenograft cells both in vitro and in vivo in nude mice.

    Directory of Open Access Journals (Sweden)

    Shivani Ponnala

    Full Text Available BACKGROUND: Glioblastoma Multiforme (GBM is the most lethal form of brain tumor. Efficient DNA repair and anti-apoptotic mechanisms are making glioma treatment difficult. Proteases such as MMP9, cathepsin B and urokinase plasminogen activator receptor (uPAR are over expressed in gliomas and contribute to enhanced cancer cell proliferation. Non-homologous end joining (NHEJ repair mechanism plays a major role in double strand break (DSB repair in mammalian cells. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that silencing MMP9 in combination with uPAR/cathepsin B effects NHEJ repair machinery. Expression of DNA PKcs and Ku70/80 at both mRNA and protein levels in MMP9-uPAR (pMU and MMP9-cathepsin B (pMC shRNA-treated glioma xenograft cells were reduced. FACS analysis showed an increase in apoptotic peak and proliferation assays revealed a significant reduction in the cell population in pMU- and pMC-treated cells compared to untreated cells. We hypothesized that reduced NHEJ repair led to DSBs accumulation in pMU- and pMC-treated cells, thereby initiating cell death. This hypothesis was confirmed by reduced Ku70/Ku80 protein binding to DSB, increased comet tail length and elevated γH2AX expression in treated cells compared to control. Immunoprecipitation analysis showed that EGFR-mediated lowered DNA PK activity in treated cells compared to controls. Treatment with pMU and pMC shRNA reduced the expression of DNA PKcs and ATM, and elevated γH2AX levels in xenograft implanted nude mice. Glioma cells exposed to hypoxia and irradiation showed DSB accumulation and apoptosis after pMU and pMC treatments compared to respective controls. CONCLUSION/SIGNIFICANCE: Our results suggest that pMU and pMC shRNA reduce glioma proliferation by DSB accumulation and increase apoptosis under normoxia, hypoxia and in combination with irradiation. Considering the radio- and chemo-resistant cancers favored by hypoxia, our study provides important therapeutic potential

  6. Adsorption of polycyclic aromatic hydrocarbons (PAHs) on Rhizopus oryzae cell walls: application of cosolvent models for validating the cell wall-water partition coefficient.

    Science.gov (United States)

    Ma, Bin; Xu, Minmin; Wang, Jiaojiao; Chen, Huaihai; He, Yan; Wu, Laosheng; Wang, Haizhen; Xu, Jianming

    2011-11-01

    The cell wall-cosolvent partition coefficients (Km) of polycyclic aromatic hydrocarbons (PAHs) were determined for Rhizopus oryzae cell walls by controlling the volume fraction of methanol (f) ranging from 0.1 to 0.5. Five cosolvent models were employed for extrapolating the cell wall-water partition coefficients (Kw) in pure water. The extrapolated Kw values of four PAHs on R. oryzae cell walls were ranged from 2.9 to 5.1. Comparison of various Kw values of pyrene generated from extrapolation and the QSPR model, together with predicted different (PD), mean percentage deviations (MPD), and root mean square errors (RSE), revealed that the performance of the LL and Bayesian models were the best among all five tested cosolvent models. This study suggests that R. oryzae cell walls play an important role in the partitioning of PAHs during bioremediation because of the high Kw of fungal cell walls.

  7. Sinomenine induces the generation of intestinal Treg cells and attenuates arthritis via activation of aryl hydrocarbon receptor.

    Science.gov (United States)

    Tong, Bei; Yuan, Xusheng; Dou, Yannong; Wu, Xin; Wang, Yuhui; Xia, Yufeng; Dai, Yue

    2016-10-01

    Sinomenine (SIN), an anti-arthritis drug, has previously been proven to exert immunomodulatory activity in rats by inducing intestinal regulatory T-cells (Treg cells). Here, we assessed the effect of SIN on the generation and function of Treg cells in autoimmune arthritis, and the underlying mechanisms in view of aryl hydrocarbon receptor (AhR). The proportions of Treg cells and IL-17-producing T-cells (Th17 cells) differentiated from naive T-cells were analyzed by flow cytometric analysis. The AhR agonistic effect of SIN was tested by analyzing the activation of downstream signaling pathways and target genes. The dependence of intestinal Treg cell induction and arthritis alleviation by SIN on AhR activation was confirmed in a mouse collagen-induced arthritis (CIA) model. SIN promoted the differentiation and function of intestinal Treg cells in vitro. It induced the expression and activity of AhR target gene, promoted AhR/Hsp90 dissociation and AhR nuclear translocation, induced XRE reporter activity, and facilitated AhR/XRE binding in vitro, displaying the potential to be an agonist of AhR. In CIA mice, SIN induced the generation of intestinal Treg cells, and facilitated the immunosuppressive function of these Treg cells as shown by an adoptive transfer test. In addition, the induction of intestinal Treg cells and the anti-arthritic effect of SIN in CIA mice could be largely diminished by the AhR antagonist resveratrol. SIN attenuates arthritis by promoting the generation and function of Treg cells in an AhR-dependent manner.

  8. Fibrin patch-based insulin-like growth factor-1 gene-modified stem cell transplantation repairs ischemic myocardium

    Science.gov (United States)

    Li, Jun; Zhu, Kai; Yang, Shan; Wang, Yulin; Guo, Changfa; Yin, Kanhua; Wang, Chunsheng

    2015-01-01

    Bone marrow mesenchymal stem cells (BMSCs), tissue-engineered cardiac patch, and therapeutic gene have all been proposed as promising therapy strategies for cardiac repair after myocardial infarction. In our study, BMSCs were modified with insulin-like growth factor-1 (IGF-1) gene, loaded into a fibrin patch, and then transplanted into a porcine model of ischemia/reperfusion (I/R) myocardium injury. The results demonstrated that IGF-1 gene overexpression could promote proliferation of endothelial cells and cardiomyocyte-like differentiation of BMSCs in vitro. Four weeks after transplantation of fibrin patch loaded with gene-modified BMSCs, IGF-1 overexpression could successfully promote angiogenesis, inhibit remodeling, increase grafted cell survival and reduce apoptosis. In conclusion, the integrated strategy, which combined fibrin patch with IGF-1 gene modified BMSCs, could promote the histological cardiac repair for a clinically relevant porcine model of I/R myocardium injury. PMID:25767192

  9. Cartilage repair by human umbilical cord blood-derived mesenchymal stem cells with different hydrogels in a rat model.

    Science.gov (United States)

    Park, Yong-Beom; Song, Minjung; Lee, Choong-Hee; Kim, Jin-A; Ha, Chul-Won

    2015-11-01

    This study was carried out to assess the feasibility of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) in articular cartilage repair and to further determine a suitable delivering hydrogel in a rat model. Critical sized full thickness cartilage defects were created. The hUCB-MSCs and three different hydrogel composites (hydrogel A; 4% hyaluronic acid/30% pluronic (1:1, v/v), hydrogel B; 4% hyaluronic acid, and hydrogel C; 4% hyaluronic acid/30% pluronic/chitosan (1:1:2, v/v)) were implanted into the experimental knee (right knee) and hydrogels without hUCB-MSCs were implanted into the control knee (left knee). Defects were evaluated after 8 weeks. The hUCB-MSCs with hydrogels composites resulted in a better repair as seen by gross and histological evaluation compared with hydrogels without hUCB-MSCs. Among the three different hydrogels, the 4% hyaluronic acid hydrogel composite (hydrogel B) showed the best result in cartilage repair as seen by the histological evaluation compared with the other hydrogel composites (hydrogel A and C). The results of this study suggest that hUCB-MSCs may be a promising cell source in combination with 4% hyaluronic acid hydrogels in the in vivo repair of cartilage defects.

  10. Increased repair of {gamma}-induced DNA double-strand breaks at lower dose-rate in CHO cells

    Energy Technology Data Exchange (ETDEWEB)

    Boucher, D.; Hindo, J.; Averbeck, D. [Centre Universitaire d' Orsay, Inst. Curie-Section de Recherche, Orsay CEDEX (France)]. E-mail: dietrich.averbeck@curie.u-psud.fr

    2004-02-01

    DNA double-strand breaks (DSBs) are highly cell damaging. We asked whether for a given dose a longer irradiation time would be advantageous for the repair of DSBs. Varying the {gamma}-irradiation dose and its delivery time (0.05 Gy/min low dose-rate (LDR) compared with 3.5 Gy/min high dose-rate), confluent Chinese hamster ovary cells (CHO-K1) and Ku80 mutant cells (xrs-6) deficient in nonhomologous end-joining (NHEJ) were irradiated in agarose plugs at room temperature using a cesium-137 {gamma}-ray source. We used pulsed-field gel electrophoresis (PFGE) to measure DSBs in terms of the fraction of activity released (FAR). At LDR, one third of DSBs were repaired in CHO-K1 but not in xrs-6 cells, indicating the involvement of NHEJ in the repair of {gamma}-induced DSBs at a prolonged irradiation incubation time. To improve DSB measurements, we introduced in our PFGE protocol an antioxidant at the cell lysis step, thus avoiding free-radical side reactions on DNA and spurious DSBs. Addition of the metal chelator deferoxamine (DFO) decreased more efficiently the basal DSB level than did reduced glutathione (GSH), showing that measuring DSBs in the absence of DFO reduces precision and underestimates the role of NHEJ in the dose-rate effect on DSB yield. (author)

  11. The effect of salinity, redox mediators and temperature on anaerobic biodegradation of petroleum hydrocarbons in microbial fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Adelaja, Oluwaseun, E-mail: o.adelaja@my.westminster.ac.uk; Keshavarz, Tajalli, E-mail: t.keshavarz@westminster.ac.uk; Kyazze, Godfrey, E-mail: g.kyazze@westminster.ac.uk

    2015-02-11

    Highlights: • Effective degradation of petroleum hydrocarbon mixtures was achieved using MFC. • Adapted anaerobic microbial consortium was used as inoculum. • Bio-electricity generation was enhanced by 30-fold when riboflavin, was added. • Optimum MFC performance was obtained at mesophilic and moderately saline conditions. • Stable MFC performance was obtained during prolonged fed-batch MFC operation. - Abstract: Microbial fuel cells (MFCs) need to be robust if they are to be applied in the field for bioremediation. This study investigated the effect of temperature (20–50 °C), salinity (0.5–2.5% (w/v) as sodium chloride), the use of redox mediators (riboflavin and anthraquinone-2-sulphonate, AQS) and prolonged fed-batch operation (60 days) on biodegradation of a petroleum hydrocarbon mix (i.e. phenanthrene and benzene) in MFCs. The performance criteria were degradation efficiency, % COD removal and electrochemical performance. Good electrochemical and degradation performance were maintained up to a salinity of 1.5% (w/v) but deteriorated by 35-fold and 4-fold respectively as salinity was raised to 2.5%w/v. Degradation rates and maximum power density were both improved by approximately 2-fold at 40 °C compared to MFC performance at 30 °C but decreased sharply by 4-fold when operating temperature was raised to 50 °C. The optimum reactor performance obtained at 40 °C was 1.15 mW/m{sup 2} maximum power density, 89.1% COD removal and a degradation efficiency of 97.10%; at moderately saline (1% w/v) conditions the maximum power density was 1.06 mW/m{sup 2}, 79.1% COD removal and 91.6% degradation efficiency. This work suggests the possible application of MFC technology in the effective treatment of petroleum hydrocarbons contaminated site and refinery effluents.

  12. The SULFs, extracellular sulfatases for heparan sulfate, promote the migration of corneal epithelial cells during wound repair.

    Directory of Open Access Journals (Sweden)

    Inna Maltseva

    Full Text Available Corneal epithelial wound repair involves the migration of epithelial cells to cover the defect followed by the proliferation of the cells to restore thickness. Heparan sulfate proteoglycans (HSPGs are ubiquitous extracellular molecules that bind to a plethora of growth factors, cytokines, and morphogens and thereby regulate their signaling functions. Ligand binding by HS chains depends on the pattern of four sulfation modifications, one o