Because of its constant renewal and high propensity for repair, the epidermis is, together with the gut and the hematopoietic
system, a tissue of choice to explore stem cell biology. Previous research over many years has revealed the complexity of
the epidermis: the heterogeneity of the stem cell compartment, with its rare, slowly cycling, multipotent, hair-follicle,
“bulge” stem cells and the more restricted interfollicular, follicle-matrix, and sebaceous-gland stem cells, which in turn
generate the large pool of transit-amplifying progeny. Stem cell activity has been used for some considerable time to repair
skin injuries, but ex-vivo keratinocyte amplification has its limitations, and grafted skin homeostasis is not totally satisfactory.
Human embryonic stem cells raise the hope that the understanding of the developmental steps leading to the generation of epidermal
stem cells and the characterization of the key signaling pathways involved in skin morphogenesis (such as p63) will be translated
into therapeutic benefit. Our recent results suggest the feasibility not only of identifying but also of amplifying human
ES cells, early ectodermal progenitors with an intact multipotent potential that might improve the quality and functionality
of grafts, provided that preclinical in vivo studies confirm our expectations from in vitro analysis.
Keywords Epidermal stem cells - Embryonic stem cells - p63 - Multipotency - Skin
The work described here was supported by funds from the Sixth EEC Framework Program under the EPISTEM project, l’Agence Nationale
pour la Recherche (ANR projets blancs), INSERM, and the Institut National Contre le Cancer (INCa).