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Query: UNIPROT:P10721 (c-kit)
 6,575 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activation and proliferation of human liver progenitor cells has been observed during acute and chronic liver diseases. Our goal was to investigate the presence of these putative progenitors in the liver of patients who underwent lobectomy for various reasons but did not show any hepatic insufficiency. Hepatic lesions were evaluated by histological analysis. Nonparenchymal epithelial (NPE) cells were isolated from samples of human liver resections located at a distance from the lesion that motivated the operation and were cultured and characterized. These cells exhibited a marked proliferative potential. They did not express the classic set of stem cell/progenitor markers (Oct-4, Rex-1, alpha-fetoprotein, CD90, c-kit, and CD34) and were faintly positive for albumin. When cultured at confluence in the presence of hepatocyte growth factor and either epidermal growth factor or fibroblast growth factor-4, they entered a differentiation process toward hepatocytes. Their phenotype was quantitatively compared with that of mature human hepatocytes in primary culture. Differentiated NPE cells expressed albumin; alpha1-antitrypsin; fibrinogen; hepatobiliary markers such as cytokeratins 7, 19, and 8/18; liver-enriched transcription factors; and genes characterized by either a fetal (cytochrome P4503A7 and glutathione S-transferase pi) or a mature (tyrosine aminotransferase, tryptophan 2,3-dioxygenase, glutathione S-transferase alpha, and cytochrome P4503A4) expression pattern. NPE cells could be isolated from the liver of several patients, irrespective of the absence or presence of lesions, and differentiated toward hepatocyte-like cells with an intermediate hepatobiliary and mature/immature phenotype. These cells are likely to represent a resident progenitor population of the adult human liver, even in the absence of hepatic failure. Disclosure of potential conflicts of interest is found at the end of this article.
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PMID:Isolation, characterization, and differentiation to hepatocyte-like cells of nonparenchymal epithelial cells from adult human liver. 1741 93

Stem cells of fetal origin lie between embryonic and adult stem cells in terms of potentiality. Because of the ethical controversy surrounding embryonic stem cells and the relatively inferior quality of adult stem cells, the use of fetal stem cells would be an attractive option in future therapeutic applications. Here, we have investigated primitive characteristics of human umbilical-cord-derived fetal mesenchymal stem cells (UC fMSCs) during extensive expansion. We have successfully isolated and cultured UC fMSCs from all UC samples, but with two early fungal contaminations. UC fMSCs proliferated without significant evidence of morphological changes, and the average cumulative population-doubling level was over 25 for about 3 months. UC fMSCs showed the positive expression of several CD markers, known to be related to MSCs, including CD73 (SH-3, 4), CD90 (Thy-1), CD105 (SH-2), CD117 (c-kit), and CD166 (ALCAM). They demonstrated primitive properties throughout the expansion period: multilineage differentiation potentials examined by functional assays, a variety of pluripotent stem cell markers including Nanog, Oct-4, Sox-2, Rex-1, SSEA-3, SSEA-4, Tra-1-60, and Tra-1-81, minimal evidence of senescence as shown by beta-galactosidase staining, and the consistent expression of telomerase activity. These results suggest that UC fMSCs have more primitive properties than adult MSCs, which might make them a useful source of MSCs for clinical applications.
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PMID:Fetal mesenchymal stem cells derived from human umbilical cord sustain primitive characteristics during extensive expansion. 1894 82

Adult tissues contain stem cells that can transdifferentiate into other cell lineages besides forming differentiated cells of their own tissue of origin. However, human adult skin-derived stem cells have a very low efficiency. Here we established a novel culture system involving bone morphogenetic protein-4 and a floating culture system with sphere-producing medium that can enrich adult stem-cell populations in vitro. Adult stem cells were isolated from useless human scar tissue. Like mesenchymal stem cells, cultured human scar tissue-derived stem cells (hSTSCs) altered their morphology and significantly increased the number of Nestin-positive cells in proportion to the alkaline phosphatase-positive cell ratio. Moreover, the expression of the pluripotency regulator Oct-4 and its target transcripts, Sox-2, c-kit, and Rex-1, was also stimulated by this culture system. Differentiation of neurogenic progenitor cells using basic fibroblast growth factor and Neurogen 2 was successfully performed in vitro more rapidly than previous reports. Neuronal differentiation results showed that our hSTSCs expressed marker of neurogenic genes, such as glial fibrillary acid protein, neural cell adhesion molecules, neuron filament-M, and microtubule-associated protein 2. These results suggest that bone morphogenetic protein-4 and the floating culture system with sphere-producing medium induced significant proliferation of hSTSCs and mediated reprogramming of the cells from adult somatic tissue into precursor state to some degree. It is thought that this new culture system might be a simple, effective, and easily manageable process for regenerative tissue repair and autotransplantation.
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PMID:Skin-derived stem cells in human scar tissues: a novel isolation and proliferation technique and their differentiation potential to neurogenic progenitor cells. 1976 87