IN-VITRO RECONSTRUCTION OF A HUMAN CAPILLARY-LIKE NETWORK IN A TISSUE-ENGINEERED SKIN EQUIVALENT

For patients with extensive burns, wound coverage with an autologous i n vitro reconstructed skin made of both dermis and epidermis should be the best alternative to split-thickness graft. Unfortunately, various obstacles have delayed the widespread use of composite skin substitut es. Insufficient vascularization has been proposed as the most likely reason for their unreliable survival. Our purpose was to develop a vas cular-like network inside tissue-engineered skin in order to improve g raft vascularization. To reach this aim, we fabricated a collagen biop olymer in which three human cell types-keratinocytes, dermal fibroblas ts, and umbilical vein endothelial cells-were cocultured. We demonstra ted that the endothelialized skin equivalent (ESE) promoted spontaneou s formation of capillary-like structures in a highly differentiated ex tracellular matrix. Immunohistochemical analysis and transmission elec tron microscopy of the ESE showed characteristics associated with the microvasculature in vivo (von Willebrand factor, Weibel-Palade bodies, basement membrane material, and intercellular junctions). We have dev eloped the first endothelialized human tissue-engineered skin in which a network of capillary-like tubes is formed. The transplantation of t his ESE on human should accelerate graft revascularization by inoscula tion of its preexisting capillary-like network with the patient's own blood vessels, as it is observed with autografts. In addition, the ESE turns out to be a promising in vitro angiogenesis model.