ADVANTAGE OF THE PRESENCE OF LIVING DERMAL FIBROBLASTS WITHIN IN-VITRO RECONSTRUCTED SKIN FOR GRAFTING IN HUMANS

Methods for serial cultivation of human keratinocytes can provide larg e quantities of epidermal cells, which have the potential of restoring the vital barrier function of the epidermis in extensive skin defects such as bums. To investigate the value of combining an epidermis with a dermal component, fibroblasts originated from the superficial dermi s were used to seed a collagen lattice as described by E. Bell (dermal equivalent). Beginning in 1981, we grafted 18 patients (burns and gia nt nevi) using 35 grafts 10 x 10 cm in size. In the course of this wor k, the original technique was modified and improved as experience was gained. We began by using small skin biopsy samples as a source of ker atinocytes cultured on a dermal equivalent before grafting in a one-st ep procedure, but this gave poor cosmetic results, because of a nonhom ogeneous epidermalization. We then chose to cover the graft bed using a two-step procedure. The first step consisted of grafting a dermal eq uivalent to provide a dermal fibroblast-seeded substrate for subsequen t in vivo epidermalization by cultured epidermal sheets. Whatever the epidermalization technique used, a living dermal equivalent applied to the graft bed was found to reduce pain, to provide good hemostasis, a nd to improve the mechanical and cosmetic properties of the graft. A n ormal undulating dermal-epidermal junction reappeared by 3 to 4 months after grafting and elastic fibers were detectable 6 to 9 months after grafting. As a result of the biosynthesis of these products, the supp leness (e.g., elasticity) of the grafts was closer to that of normal s kin than the cicatricial skill usually obtained with epidermal sheets grafted without the presence of living dermal cells. This rapid improv ement of the mechanical properties of the graft could be attributed to the presence of fibroblasts cultured from the dermis and seeded into the collagen matrix.