Skin-resident stem cells and wound healing.

CD271 is common stem cell marker for the epidermis and dermis. We assessed a kinetic movement of epidermal and dermal CD271+ cells in the wound healing process to elucidate the possible involvement with chronic skin ulcers. Epidermal CD271+ cells were proliferated and migrated from 3 days after wounding. Purified epidermal CD271+ cells expressed higher TGFβ2 and VEGFα transcripts than CD271- cells. Delayed wound healing was observed in the aged mice compared with young mice. During the wound healing process, the peak of dermal CD271+ cell accumulation was delayed in aged mice compared with young mice. The expression levels of collagen-1, -3, -5, F4-80, EGF, FGF2, TGFβ1, and IL-1α were significantly increased in young mice compared with aged mice. Furthermore, purified dermal CD271+ cells expressed higher FGF2, EGF, PDGFB, and TGFβ1 gene transcripts than CD271- cells. These results suggested that epidermal and dermal CD271+ cells were closely associated with wound healing process by producing various growth factors. Epidermal and dermal CD271+ cells in chronic skin ulcer patients were significantly reduced compared with healthy controls. Thus, both epidermal and dermal stem cells can play an important role in wound healing process.