[In vitro cutaneous organogenesis (application to skin grafts)]

The culture of cutaneous fibroblasts in an environment of collagen results in a resistant, three-dimensional culture in which fibroblasts are differentiated. This dermal sheet can be covered with an epidermal cell layer which will allow to rebuild an in vitro human skin equivalent. This in vitro organogenesis technique was used since 1983 to treat burns and children suffering from severe cutaneous malformations (giant naevi). The results which were obtained after 33 grafts on 16 patients show that, if the epidermal graft is essential to preserve patients' lives the dermal constituent is also important in the long-term since it induces the synthesis, 3 to 6 months later, of numerous elastic fibers which give to the graft mechanical properties close to that of the normal skin as well as the recovery of a normal micro relief. These cutaneous reconstructions can be completed in one or, even better, two stages which enable the successive graft of reconstructed dermis and epidermal sheets, the latter obtained in great quantity thank's to Grenn's method. The conditions of preparation of these living biomaterials require rigorous quality controls. Their further development is of great interest since it will improve skin replacement and will be a very interesting tool for gene therapy.