Human umbilical cord blood cells form epidermis in the skin equivalent model.

Recently, human embryonic stem cells have been differentiated in vitro into functional epidermal keratinocytes. Here, we demonstrated that these cells can be generated also from non-embryonic, human umbilical cord blood (hUCB) cells that have the potential to differentiate into cells of non-hematopoietic lineage. Human UCB mono-nucleated cells were cultivated in monolayer and in three-dimensional skin equivalent cultures and assayed for the presence of phenotype-specific markers. Our results determined that after one month of culturing in serum containing medium, the hUCB cells produced morphologically homogeneous colonies of epithelial cells expressing keratinocyte-specific markers. They also formed stratified epidermis in organ cultures that contained sporadic CD1a-positive cells within the accurate strata. We concluded that hUCB cells have the capacity to differentiate into functional epidermal keratinocytes and may serve as a source of high-quality keratinocytes for clinical applications.