| Stem cell separation: A bottleneck in stem cell therapy.
December 1, 2009 at 10:49 am
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| | Stem cell separation: A bottleneck in stem cell therapy. Biotechnol J. 2009 Nov 27; Authors: Schriebl K, Lim S, Choo A, Tscheliessnig A, Jungbauer A The substantial progress in embryonic stem cell (ESC) research could lead to new possibilities in the treatment of various diseases. Currently, applications of ESC for cell therapy are impeded by the presence of potentially teratoma-forming undifferentiated ESC. Thus, a selective and quantitative removal of undifferentiated ESC from a pool of differentiated and undifferentiated cells is essential before cell therapy. We evaluated the highly selective magnetic activated cell sorting (MACS) method for the quantitative removal of undifferentiated ESC. We found that the clearance rates for undifferentiated ESC decreased with decreasing amount of undifferentiated ESC in the cell pool. Using a simplified model calculation we could predict that, assuming an initial purity of 60%, an estimated 31 steps are required to achieve less than 10(-1) cell per 10(9) cells. Thus, a log clearance rate of 10, which would be necessary for a therapeutically application, is hard to achieve. Our work clearly indicates that the current MACS technology is insufficient to meet the purification needs for cell therapy. PMID: 19946874 [PubMed - as supplied by publisher] |
| On the Effects of UV-C and pH on the Mechanical Behavior, Molecular Conformation and Cell Viability of Collagen-Based Scaffold for Vascular Tissue Engineering.
December 1, 2009 at 10:49 am
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| | On the Effects of UV-C and pH on the Mechanical Behavior, Molecular Conformation and Cell Viability of Collagen-Based Scaffold for Vascular Tissue Engineering. Macromol Biosci. 2009 Nov 27; Authors: Achilli M, Lagueux J, Mantovani D Collagen-based vascular substitutes represent in VTE a valid alternative for the replacement of diseased small-calibre blood vessels. In this study, collagen gel-based scaffolds were crosslinked combining modulation of pH and UV-C radiation. The effects on the mechanical properties, on the molecular structure and on cell viability and morphology were investigated. The mechanical response increased as a function of pH or UV-C dose and strongly depended on the test speed. Collagen molecular conformation resulted only slightly modified. While cell adhesion was not significantly altered, cell proliferation partially decreased in function of pH and UV-C. These findings suggest that UV-C treated collagen gels can represent an adequate substrate for VTE applications. PMID: 19946859 [PubMed - as supplied by publisher] |
| Effects of Culturing on the Stability of the Putative Murine Adipose Derived Stem Cells Markers.
December 1, 2009 at 10:49 am
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| | Effects of Culturing on the Stability of the Putative Murine Adipose Derived Stem Cells Markers. Open Stem Cell J. 2009 Jan 1;1:54-61 Authors: Maddox JR, Liao X, Li F, Niyibizi C Mesenchymal stem cells have generated much interest because of their potential use in regenerative medicine. The major draw back in the application of these cells is that there is no single marker or markers that have been established to identify and aid in isolating the cells from a variety of other cell types. The commonly expressed mesenchymal stem cell surface antigens include CD44, CD73, CD90.2, CD105, and CD146. In the present study we examined the stability of these surface antigens in culture and their potential application in identifying and isolating murine derived adipose derived stem cells. The data showed that the expression of these markers increased with culturing and appeared to stabilize by passage 8; the cells were sorted positively for the surface markers at this passage. Each subset was maintained in culture and evaluated for differentiation toward osteogenic lineage in vitro and in vivo. The CD73 and CD105 positive cell subsets demonstrated robust differentiation toward osteogenic lineage in vitro; the CD90.2+ cell subset exhibited the least differentiation toward osteogenic lineage. Assessment of the cell subpopulations for in vivo differentiation demonstrated that all the cell subsets exhibited potential to differentiate into osteoblasts. Taken together, these data suggest that this panel of markers although useful in identifying cells with potential to differentiate toward osteogenic lineage, cannot prospectively be used for enriching for ADSC from a variety of other cell types. PMID: 19946473 [PubMed - as supplied by publisher] |
| Nanostructured Biomaterials for Regeneration.
December 1, 2009 at 10:49 am
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| | Nanostructured Biomaterials for Regeneration. Adv Funct Mater. 2008 Nov 24;18(22):3566-3582 Authors: Wei G, Ma PX Biomaterials play a pivotal role in regenerative medicine, which aims to regenerate and replace lost/dysfunctional tissues or organs. Biomaterials (scaffolds) serve as temporary 3D substrates to guide neo tissue formation and organization. It is often beneficial for a scaffolding material to mimic the characteristics of extracellular matrix (ECM) at the nanometer scale and to induce certain natural developmental or/and wound healing processes for tissue regeneration applications. This article reviews the fabrication and modification technologies for nanofibrous, nanocomposite, and nanostructured drug-delivering scaffolds. ECM-mimicking nanostructured biomaterials have been shown to actively regulate cellular responses including attachment, proliferation, differentiation and matrix deposition. Nano-scaled drug delivery systems can be successfully incorporated into a porous 3D scaffold to enhance the tissue regeneration capacity. In conclusion, nano-structured biomateials are a very exciting and rapidly expanding research area, and are providing new enabling technologies for regenerative medicine. PMID: 19946357 [PubMed - as supplied by publisher] |
| Nongenetic method for purifying stem cell-derived cardiomyocytes.
December 1, 2009 at 10:49 am
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| | Nongenetic method for purifying stem cell-derived cardiomyocytes. Nat Methods. 2009 Nov 29; Authors: Hattori F, Chen H, Yamashita H, Tohyama S, Satoh YS, Yuasa S, Li W, Yamakawa H, Tanaka T, Onitsuka T, Shimoji K, Ohno Y, Egashira T, Kaneda R, Murata M, Hidaka K, Morisaki T, Sasaki E, Suzuki T, Sano M, Makino S, Oikawa S, Fukuda K Several applications of pluripotent stem cell (PSC)-derived cardiomyocytes require elimination of undifferentiated cells. A major limitation for cardiomyocyte purification is the lack of easy and specific cell marking techniques. We found that a fluorescent dye that labels mitochondria, tetramethylrhodamine methyl ester perchlorate, could be used to selectively mark embryonic and neonatal rat cardiomyocytes, as well as mouse, marmoset and human PSC-derived cardiomyocytes, and that the cells could subsequently be enriched (>99% purity) by fluorescence-activated cell sorting. Purified cardiomyocytes transplanted into testes did not induce teratoma formation. Moreover, aggregate formation of PSC-derived cardiomyocytes through homophilic cell-cell adhesion improved their survival in the immunodeficient mouse heart. Our approaches will aid in the future success of using PSC-derived cardiomyocytes for basic and clinical applications. PMID: 19946277 [PubMed - as supplied by publisher] |
| Stem cells in cardiac repair in an inflammatory microenvironment.
December 1, 2009 at 10:49 am
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| | Stem cells in cardiac repair in an inflammatory microenvironment. Minerva Cardioangiol. 2009 Nov 30; Authors: Rameshwar P, Qiu H, Vatner SF Despite advances in clinical interventions, drug therapy and preventative strategies for cardiovascular disease, heart disease remains the number one cause of death in the United States. A major cause of heart failure leading to death is myocardial ischemic disease. Terminal heart failure can be salvaged in some cases by cardiac transplants, but this therapeutic approach is limited by lack of supply, high cost, and problems with immunosuppression. An attractive alternative approach proposed over the last 1-2 decades is the replacement of myocardium at the level of the myocyte, which has focused on stem cell therapy. This form of therapy has been successful for hematopoietic replacement. Similar therapy has been proposed to treat hearts ravaged by ischemic necrosis and apoptosis. However, the experimental studies have not been effectively translated to patients with myocardial infarction or heart failure. This review discusses the current literature and points out key studies that are required for future directions, focusing on key roles for microenvironmental factors, such as cytokines, in stem cells responses when placed at sites of cardiac injuries. In the case of mesenchymal stem cells (MSCs), they exert both immune- enhancer and -suppressor functions, which are referred to as immune plasticity. This type of immune properties by MSCs is significant to therapeutic outcomes. Thus, the plasticity of MSCs, with regards to immune responses, has to be considered carefully in tissue repair and replacement and in gene delivery systems. The route by which cytokines are delivered as adjuvant to cell therapy, or as methods to mobilize stem cells, will show varied results, depending on the degree of injury, underlying clinical disorders and other diverse parameters, such as ethnicity, age and genomic profile. In addition to MSCs, roles exist for other stem cells, such as those from placenta, cord blood, hematopoietic stem/progenitor cells and cardiac stem cells. PMID: 19946252 [PubMed - as supplied by publisher] |
| Sex steroid-mediated reprogramming of vascular smooth muscle cells to stem cells and neurons: Possible utilization of sex steroid combinations for regenerative treatment without utilization of in vitro developed stem cells.
December 1, 2009 at 10:49 am
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| | Sex steroid-mediated reprogramming of vascular smooth muscle cells to stem cells and neurons: Possible utilization of sex steroid combinations for regenerative treatment without utilization of in vitro developed stem cells. Cell Cycle. 2009 Dec 21;8(24) Authors: Bukovsky A Previous work from our laboratory demonstrated that sex steroid combinations, but not individual sex steroids alone, cause transdifferentiation of ovarian epithelial cells-ovarian surface epithelium (OSE) and follicular granulosa cells-into neural stem cells (NSC) and differentiating neurons. In the present study we have chosen primary culture of human vascular smooth muscle cells (SMC), a non-epithelial mesenchymal cells in order to test them as a control cell type regarding their morphology and expression of NSC and neuronal markers. Utilization of estradiol (E2), progesterone (PG) or testosterone (TS) alone did not induce the emergence of neurons from the vascular SMC. However, the treatment with sex steroid combinations (PG + TS or E2 + PG + TS) caused transdifferentiation into neural/neuronal type cells. By immunohistochemistry, these cells exhibited strong expression of stem cell markers and neural/neuronal glycoconjugates SSEA-1, SSEA-4, Thy-1, NeuN and NCAM. In the Neurobasal/B27 medium both, the OSE and vascular SMC also transdifferentiated into neuronal cells. Western blot analysis has shown significant increase of NeuN 48-kDa species after E2 + PG or PG + TS treatment. Secretion of E2 increased significantly in vascular SMC cultures pretreated with TS, PG or TS + PG. Unlike OSE cells, the vascular SMC accompany as pericytes all vessels, including CNS microvasculature. We also observed that sex steroid combinations could produce SMC stem type cells which differentiated within a few days back to mature vascular SMC. This is of potential interest for the vascular regenerative medicine. Altogether, our observations suggest that sex steroid combinations could induce in vivo improvement of neurodegenerative, traumatic and ischemic neurological disorders and vascular diseases via their effect on resident pluripotent vascular SMC, i.e., without a need of in vitro developed stem cells. PMID: 19946214 [PubMed - as supplied by publisher] |
| Fluoride-containing bioactive glasses inhibit pentose phosphate oxidative pathway and glucose 6-phosphate dehydrogenase activity in human osteoblasts.
December 1, 2009 at 10:49 am
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| | Fluoride-containing bioactive glasses inhibit pentose phosphate oxidative pathway and glucose 6-phosphate dehydrogenase activity in human osteoblasts. Chem Biol Interact. 2009 Nov 26; Authors: Bergandi L, Aina V, Garetto S, Malavasi G, Aldieri E, Laurenti E, Matera L, Morterra C, Ghigo D Bioactive glasses such as Hench's 45S5 (Bioglass((R))) have applications to tissue engineering as well as bone repair, and the insertion of fluoride in their composition has been proposed to enhance their bioactivity. In view of a potential clinical application, we investigated whether fluoride-containing glasses exert toxic effects on human MG-63 osteoblasts, and whether and how fluoride, which is released in the cell culture medium, might play a role in such cytotoxicity. A 24h incubation with 50mug/ml (12.5mug/cm(2)) of fluoride-containing bioactive glasses termed HCaCaF(2) (F content: 5, 10 and 15% mol) caused the release of lactate dehydrogenase in the extracellular medium (index of cytotoxicity), the accumulation of intracellular malonyldialdehyde (index of lipoperoxidation), and the increase of glutathione consumption. Furthermore, fluoride-containing glasses inhibited the pentose phosphate oxidative pathway and the glucose 6-phosphate dehydrogenase activity. These effects are ascribable to the fluoride content/release of glass powders, since they were mimicked by NaF solutions and were prevented by dimethyl sulfoxide and tempol (two radical scavengers), by superoxide dismutase (a superoxide scavenger), and by glutathione (the most important intracellular antioxidant molecule), but not by apocynin (an inhibitor of NADPH oxidase). The presence of fluoride-containing glasses and NaF caused also the generation of reactive oxygen species, which was prevented by superoxide dismutase and catalase. The data suggest that fluoride released from glasses is the cause of MG-63 cell oxidative damage and is independent of NADPH oxidase activation. Our data provide a new mechanism to explain F(-) ions toxicity: fluoride could trigger, at least in part, an oxidative stress via inhibition of the pentose phosphate oxidative pathway and, in particular, through the oxidative inhibition of glucose 6-phosphate dehydrogenase. PMID: 19945446 [PubMed - as supplied by publisher] |
| Isolation of multipotent stem cells in human periodontal ligament using stage-specific embryonic antigen-4.
December 1, 2009 at 10:49 am
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| | Isolation of multipotent stem cells in human periodontal ligament using stage-specific embryonic antigen-4. Differentiation. 2009 Nov 26; Authors: Kawanabe N, Murata S, Murakami K, Ishihara Y, Hayano S, Kurosaka H, Kamioka H, Takano-Yamamoto T, Yamashiro T The periodontal ligament (PDL) comprises adult stem cells, which are responsible for periodontal tissue regeneration. In the present study, we investigated the specific profile of the stem cells in the human PDL. Microscopic analysis demonstrated that PDL cells showed a fibroblastic appearance, forming flat and loose aggregates. PDL cells expressed embryonic stem cell-associated antigens (SSEA-1, SSEA-3, SSEA-4, TRA-1-60, TRA-1-81, OCT4, NANOG, SOX2, and REX1, and alkaline phosphatase activity), as well as conventional mesenchymal stem cell markers. When PDL cells were cultured in the presence of all-trans-retinoic acid, the numbers of SSEA-3+ and SSEA-4+ PDL cells were significantly decreased, while that of SSEA-1+ was increased. SSEA-4+ PDL cells showed a greater telomere length and growth rate. SSEA-4+ PDL cells exhibited the potential to generate specialized cells derived from three embryonic germ layers: mesodermal (adipocytes, osteoblasts, and chondrocytes), ectodermal (neurons), and endodermal (hepatocytes) lineages. Our findings demonstrated that SSEA-4, a major antigen to distinguish human embryonic stem cells, could also be used to identify multipotent stem cells in the PDL. Hence, SSEA-4+ human PDL cells appear to be a promising source of stem cells for regenerative medicine. PMID: 19945209 [PubMed - as supplied by publisher] |
| Scientific investments continue to fuel improvements in oral health (may 2000-present).
December 1, 2009 at 10:49 am
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| | Scientific investments continue to fuel improvements in oral health (may 2000-present). Acad Pediatr. 2009 Nov-Dec;9(6):383-5 Authors: Slayton RL, Slavkin HC The release of Oral Health in America: A Report of the Surgeon General in May 2000 raised national, state, and local awareness, for the first time ever, of the impact of oral disease in America. The report emphasized oral health's link to general health and well-being, and called for a national effort among individuals, communities, and health care providers to improve oral health among all Americans. One of the objectives from the Surgeon General's Report On Oral Health was to "advance the science base and translate into practice." Our objective here is to address how the science base has progressed in 3 main areas that have significant potential to impact oral health: sequencing of the human genome, tissue engineering, and saliva diagnostics. A secondary objective is to comment on progress in our understanding of dental caries and its impact on young children. PMID: 19945072 [PubMed - in process] |
| Hepatitis B virus induced coupling of deadhesion and migration of HepG2 cells on thermo-responsive polymer.
December 1, 2009 at 10:49 am
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| | Hepatitis B virus induced coupling of deadhesion and migration of HepG2 cells on thermo-responsive polymer. Biomaterials. 2009 Nov 25; Authors: Li X, Feng H, Chen WN, Chan V The unique physical property of thermo-responsive polymer (TRP) has recently prompted its increasing applications in tissue engineering. On the other hand, TRP has not been exploited for potential applications in quantitative cell screening against external stimulations. In this study, TRP is applied as a model system for elucidating the effect of HBV replication on the biophysical responses of HepG2 cells transfected by wild type HBV genome. Moreover, mutant HBV genome is designed to assess the specific activity of the SH3-binding domain of HBx during HBV replication. The adhesion contact recession and geometry transformation of HepG2 cells transfected with empty vector (pcDNA3.1 cells), wild type HBV (wtHBV cells) and mutant HBV genome (mHBV cells) are probed during the thermal transformation across lower solution critical temperature of TRP. In comparison with pcDNA3.1 cells and mHBV cells, the initial rate of reduction in degree of deformation and average adhesion energy for wtHBV cells is significantly increased. Interestingly, migration speed and persistence time of cells are found to be correlated with the cell deadhesion kinetics. Immuno-fluorescence microscopy demonstrates that HBV replication reduces the actin concentration and focal adhesions at cell periphery during the initial 30 min cell deadhesion. The results strongly suggested that HBV infection triggers the dynamic responses of HepG2 cells through the cytoskeleton remodeling and subsequent mechanochemical transduction. Overall, it is shown that TRP provides a convenient platform for quantifying biological stimulations on adherent cells. PMID: 19944459 [PubMed - as supplied by publisher] |
| Tumor risk by tissue engineering: cartilaginous differentiation of mesenchymal stem cells reduces tumor growth.
December 1, 2009 at 10:49 am
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| | Tumor risk by tissue engineering: cartilaginous differentiation of mesenchymal stem cells reduces tumor growth. Osteoarthritis Cartilage. 2009 Nov 24; Authors: Akay I, Oxmann D, Helfenstein A, Mentlein R, Schünke M, Hassenpflug J, Kurz B OBJECTIVE: Implantation of autologous chondrocytes (AC) is a promising option for the treatment of cartilage defects, but problems with cell harvesting, dedifferentiation, or the donor age limit the clinical outcome. Mesenchymal stem cells (MSC) gain much interest because of their simple isolation and multipotential differentiation capacity along with their immunosuppressive properties. The latter might introduce tumor manifestation. The influence of undifferentiated and chondrogenically differentiated MSC or AC on tumor growth and metastasis formation was investigated in a murine melanoma model. METHODS: Allogeneic melanoma cells and either syngeneic MSC (C3H10T1/2, transduced with enhanced green fluorescent protein gene) or AC were co-injected at a distance of 3cm into the contra lateral groins of five mice/group, and evaluated macroscopically and histologically after 4 weeks. RESULTS: Undifferentiated MSC migrated to the tumor site and induced strong tumor growth and metastasis formation. Even avital MSC promoted tumor growth and spreading, but insignificantly without detectable MSC at the tumor site. Chondrogenically differentiated MSC did not migrate and had a significantly lower impact on tumor growth and spreading; AC had no measurable influence on melanoma cells. CONCLUSIONS: Our data suggest that differentiation of MSC reduces MSC-dependent promotion of latent tumors and that native AC do not introduce any increased risk of tumor growth. The question of how far MSC should be differentiated prior to clinical application should be addressed in further studies. PMID: 19944200 [PubMed - as supplied by publisher] |
| The effect of ethylene-oxide, glow-discharge and electron-beam on the surface characteristics of poly(L-lactide-co-caprolactone) and the corresponding cellular response of adipose stem cells.
December 1, 2009 at 10:49 am
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| | The effect of ethylene-oxide, glow-discharge and electron-beam on the surface characteristics of poly(L-lactide-co-caprolactone) and the corresponding cellular response of adipose stem cells. Acta Biomater. 2009 Nov 24; Authors: Kroeze RJ, Helder MN, Roos WH, Wuite GJ, Bank RA, Smit TH Bioabsorbable polymers are increasingly being used in tissue engineering strategies. Despite the knowledge that some sterilization techniques may affect the physical properties of these polymers, this aspect is often overlooked. We speculate that the type of sterilization method used may influence the cellular responses by altering the surface characteristics. We cultured adipose stem cells onto bioabsorbable poly(L-lactide-co-caprolactone) (PLCL) sheets, sterilized using either ethylene-oxide (EO), argon glow-discharge (aGD), or electron-beam (E-beam). Significant higher values in surface roughness corresponding to EO>aGD>E-beam and significant differences in contact angles (EO>E-beam>aGD) and surface energies (aGD>E-beam>EO) were observed. Increased cell-attachment and proliferation rates were observed with lower contact angles. The alkaline-phosphatase activity was significantly higher for the ethylene-oxide sterilized PLCL sheet. In conclusion, the type of sterilization for bioabsorbable polymers should be considered in the design of new scaffolds, since it might affect, or can be used to enhance, the outcome of the tissue engineered construct. PMID: 19944190 [PubMed - as supplied by publisher] |
| RGMb controls aggregation and migration of Neogenin-positive cells in vitro and in vivo.
December 1, 2009 at 10:49 am
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| | RGMb controls aggregation and migration of Neogenin-positive cells in vitro and in vivo. Mol Cell Neurosci. 2009 Nov 24; Authors: Conrad S, Stimpfle F, Montazeri S, Oldekamp J, Seid K, Alvarez-Bolado G, Skutella T The proliferation, migration and differentiation of dentate gyrus stem and precursor cells have aroused keen interest. Neogenin and RGMb are expressed in non-overlapping compartments of the developing dentate gyrus. While Neogenin is expressed in migrating and proliferating dentate precursors, RGMb is localized in structures bordering the developing dentate, such as cornus ammonis cells and Cajal Retzius cells in the marginal zone including the hippocampal fissure. Co-immunoprecipitation and binding assays indicate a strong physical interaction. In vitro and in vivo migration of dentate neuroepithelial cells is abolished by RGMb, and cell adhesion is reduced when cells expressing Neogenin come into contact with cells expressing RGMb. Ectopic expression of RGMb in organotypic slice cultures and after in utero electroporation in the hippocampus modifies precursor cell migration. Our results imply that Neogenin-RGMb interaction might be involved in neuronal migration in the dentate gyrus. PMID: 19944164 [PubMed - as supplied by publisher] |
| Neurotrophic regulation of fibroblast dedifferentiation during limb skeletal regeneration in the axolotl (Ambystoma mexicanum).
December 1, 2009 at 10:49 am
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| | Neurotrophic regulation of fibroblast dedifferentiation during limb skeletal regeneration in the axolotl (Ambystoma mexicanum). Dev Biol. 2009 Nov 24; Authors: Satoh A, Cummings GM, Bryant SV, Gardiner DM The ability of animals to repair tissue damage is widespread and impressive. Among tissues, the repair and remodeling of bone occurs during growth and in response to injury; however, loss of bone above a threshold amount is not regenerated, resulting in a "critical-size defect" (CSD). The development of therapies to replace or regenerate a CSD is a major focus of research in regenerative medicine and tissue engineering. Adult urodeles (salamanders) are unique in their ability to regenerate complex tissues perfectly, yet like mammals do not regenerate a CSD. We report on an experimental model for the regeneration of a CSD in the axolotl (the Excisional Regeneration Model) that allows for the identification of signals to induce fibroblast dedifferentiation and skeletal regeneration. This regenerative response is mediated in part by BMP signaling, as is the case in mammals; however, a complete regenerative response requires the induction of a population of undifferentiated, regeneration-competent cells. These cells can be induced by signaling from limb amputation to generate blastema cells that can be grafted to the wound, as well as by signaling from a nerve and a wound epithelium to induce blastema cells from fibroblasts within the wound environment. (195 words). PMID: 19944088 [PubMed - as supplied by publisher] | | | 
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