cells • Tissue regeneration • Skin grafts

Vascularization is the cornerstone of wound healing. We introduced human blood outgrowth endothelial cells (hBOEC) in a self-assembled human dermal fibroblast sheet (hDFS), intended as a tissue-engineered dermal substitute with inherent vascular potential. hBOEC were functionally and molecularly different from early endothelial progenitor cells and human umbilical vein endothelial cells (HUVEC). hBOEC alone, unlike HUVEC, efficiently revascularized and re-oxygenated the wound bed, both by active incorpo-ration into new vessels and by trophic stimulation of host angiogenesis in a dose-dependent manner. Furthermore, hBOEC alone, but not HUVEC, accelerated epithelial cov-erage and matrix organization of the wound bed. In addi-tion, integration of hBOEC in hDFS not only further improved vascularization, epithelial coverage and matrix organization but also prevented excessive wound contrac-tion. In vitro analyses with hBOEC, fibroblasts and kerati-nocytes revealed that these effects were both due to growth factor crosstalk and to short cutting hypoxia. Among multi-ple growth factors secreted by hBOEC, placental growth factor mediated at least in part the beneficial effects on ke-ratinocyte migration and proliferation. Overall, this com-bined tissue engineering approach paves the way for clinical development of a fully autologous vascularized der-mal substitute for patients with large skin defects that do not heal properly. STEM CELLS 2010;28:1165–1177 Disclosure of potential conflicts of interest is found at the end of this article