In vitro transdifferentiation of corneal epithelial-like cells from human skin-derived precursor cells

The damage of human corneal cells encounter with the problem of availability of corneal cells for replacement. Limitation of the source of corneal cells has been realized. An attempt of development of corneal epithelial-like cells from the human skin-derived precursor (hSKPs) has been made in this study. Combination of three essential growth factors: epidermal growth factor (EGF), keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF) could demonstrate successfully induction of hSKPs to differentiation into corneal cells.The induced cells expressed the appearance of markers of corneal epithelial cells as shown by the presence of keratin 3 (K3) by antibody label and Western blot assay. The K3 gene expression of induced hSKPs cells as shown by reverse transcription-polymerase chain reaction (RT-PCR) technology was also demonstrated. The presence of these markers at both gene and protein levels could lead to our conclusion that the directional transdifferentiation of hSKPs cells into corneal epithelial cells was successfully done under this cell induction protocol. The finding shows a newly available stem cell source can be obtained from easily available skin. Cells from autologous human skin might be used for corneal disorder treatment in future clinical application.

Epithelial cells with hepatobiliary phenotype:Is it another stem cell candidate for healthy adult human liver?

AIM： To investigate the presence and role of liver epithelial cells in the healthy human adult liver. METHODS： Fifteen days after human hepatocyte primary culture, epithelial like cells emerged and started proliferating. Cell colonies were isolated and sub- cultured for more than 160 d under specific culture conditions. Cells were analyzed for each passage using immunofluorescence, flow cytometry and reverse transcription-polymerase chain reaction （RT-PCR）. RESULTS： Flow cytometry analysis demonstrated that liver epithelial cells expressed common markers for hepatic and stem cells such as CD90, CD44 and CD29 but were negative for CD34 and CDl17. Using immunofluorescence we demonstrated that liver epithelial cells expressed not only immature （α-fetoprotein） but also differentiated hepatocyte （albumin and CK-18） and biliary markers （CK-7 and 19）, whereas they were negative for OV-6. RT-PCR analysis confirmed immunofluorescence data and revealed that liver epithelial cells did not express mature hepatocyte markers such as CYP2B6, CYP3A4 and tyrosine amino-transferase. Purified liver epithelial cells were transplanted into SCID mice. One month after transplantation, albumin positive cell foci were detected in the recipient mouse parenchyma. CONCLUSION： According to their immature and bipotential phenotype, liver epithelial cells might represent a pool of precursors in the healthy human adult liver other than oval cells.