A preexisting microvascular network benefits in vivo revascularization of a microvascularized tissue-engineered skin substitute.

Delayed or absence of vascularization is one of the major reasons for skin engraftment failure in patients with extensive burns. For such trauma victims, the best alternative to a split-thickness graft would be wound coverage with an autologous in vitro reconstructed skin (RS) combining dermis and epidermis with an appropriate microvascularization. We have developed an endothelialized RS based on our self-assembly approach, which is generated from autologous cultured cells without any exogenous angiogenic growth factor or scaffold. After transplantation in athymic mice, an early inosculation between the graft and host vasculatures occurred within 4 days. We also concurrently detected an active invasion of the dermis by host capillaries sprouting from the wound bed. Thus, the microvascular network constructed in vitro within our three-dimensional skin substitute did not only develop functional anastomoses with the host's blood vessels but also promoted a rapid, complete, and optimal vascularization of the implanted tissues by exerting an angiogenic effect compared with control RS. Our model may bring about interesting possibilities for regenerative medicine by leading to faster vascularization in clinical applications. In addition, the endothelialized RS can be a useful in vitro angiogenesis model.