Cultured human epithelium: human umbilical cord blood stem cells differentiate into keratinocytes under in vitro conditions

BACKGROUND: Stem cells have the capacity to renew or to give rise to a specialized cell types. Human umbilical cord blood (HUCB) has been explored as an alternative source of stem cells. However, its potential to differentiate into cells of other tissues is still under discussion. The aim of our study was to evaluate if HUCB stem cells could differentiate into epithelial cells under in vitro conditions. METHODS: Human keratinocytes derived from adult female skin donors, were isolated and cultured on fibrin glue/fibroblast gels-control group. In the umbilical cord blood cell group, male umbilical cord blood cells were added at a 1:10 ratio to keratinocytes and co-cultured on the fibrin glue/fibroblasts gel. After 15 days of culture, the sheets were analyzed by use of histochemistry and FISH. DNA was extracted and evaluated by use of polymerase chain reaction (PCR) for detection of Y-chromosome-specific sequences. RESULTS: In both groups a regular epithelial sheet consisting of three to four layers of cells was formed. Using PCR and FISH, in the umbilical cord blood cell group the presence of Y-chromosome-specific sequences in the cultured keratinocytes could be detected. In the control group, no Y-chromosome-specific sequences could be detected. CONCLUSION: Our findings indicate that umbilical cord blood stem cells differentiate into epithelial cells under in vitro conditions and thereby, might serve as a starting material for isolation and expansion of cells for transplantation in patients with large skin defects.