[Pluripotency and induced nuclear reprogramming in vertebrates: new perspectives].

Pluripotency is a transitory state during vertebrate development. A pluripotent cell can theoretically acquire all cell fates of the organism. During ontogenetic dynamics, loss of pluripotency is associated with a progressive acquisition of a specific genetic program, which is determined both by instructions received and by cell position in the whole organism. Pluripotent embryonic stem cells can be isolated and cultured in vitro indefinitely. Using mammalian embryonic stem cells (ESCs), it has been possible to identify the factors involved in the establishment and maintenance of pluripotency state. In this review, we will describe recent scientific advances in the understanding of pluripotency, the molecular actors involved in such a regulation and their functional conservation during evolution. We shall focus on new concepts, obtained from the study of vertebrate model organisms, to shed light on the cell transition from pluripotency to differentiated state, and shall recapitulate fundamental and clinical applications of pluripotent cells, of "somatic cell nuclear transfer" (SCNT), of induced nuclear reprogramming in vitro and future perspectives of in vivo applications. Our results, in the xenopus, concerning the first in vivo induced nuclear reprogramming might open new perspectives about the understanding of cell plasticity in an integrated context. Our analyses sought to encourage new and alternative clinical approaches to achieve in situ tissue regeneration.