560 Isolation of an “early” transit amplifying keratinocyte population in interfollicular human epidermis: a role for CD271 receptor

In the interfollicular epidermis stem cells (KSC) generate transit amplifying (TA) that, after symmetric divisions, produce differentiating daughters. We isolated and characterized highly proliferative epidermal basal cell population “early” TA (ETA) cells, based on its capacity to adhere type IV collagen. Proliferation colony forming efficiency in ETA are lower than KSC, but higher “late” (LTA). Stem differentiation markers confirmed that display a unique phenotype. Skin reconstructs derived from present different features (epidermal thickness, Ki67 survivin expression), as compared skin equivalents generated either KSC or LTA cells. The low affinity neurotrophin receptor CD271, regulates transition human through an on/off switch control mechanism, is predominantly expressed siRNA CD271 more less differentiated phenotype, mock-derived reconstructs. Consistently, overexpression generates equivalent mock Finally, expression declines with ageing cellular senescence. addition, overexpressing show p16ink4a levels during replicative senescence also appears delay comparison conclude represent first progenitor exclusive features. identifies modulates thus participating early regenerative of epidermis.