VEGF contributes to postnatal neovascularization by mobilizing bone marrow-derived endothelial progenitor cells

Vascular endothelial growth factor (VEGF) has been shown to promote neovasc ularization in animal models and, more recently, in human subjects. This fe ature has been assumed to result exclusively from its direct effects on ful ly differentiated endothelial cells, i.e. angiogenesis. Given its regulator y role in both angiogenesis and vasculogenesis during fetal development, we investigated the hypothesis that VEGF may modulate endothelial progenitor cell (EPC) kinetics for postnatal neovascularization, Indeed, we observed a n increase in circulating EPCs following VEGF administration in vivo. VEGF- induced mobilization of bone marrow-derived EPCs resulted in increased diff erentiated EPCs irt vitro and augmented corneal neovascularization in vivo. These findings thus establish a novel role for VEGF in postnatal neovascul arization which complements its known impact on angiogenesis.