[Physiological angiogenesis]

Physiological angiogenesis occurs during embryonic development but also in adults, during the female reproductive cycle (in the endometrium, corpus luteum and placenta), exercise or in wound-healing processes. Regulation of angiogenesis is classically understood as a dynamic balance between activators and inhibitors. It requires the combined activities of numbers of growth factors such as VEGF and angiopoietins. VEGF is essential from the earliest stages of vascular formation. It induces endothelial cell differentiation, migration and proliferation. Angiopoietins participate in maturation and stabilization of blood vessels and, in some conditions, in vascular regression. Comprehension of the molecular and cellular mechanisms that regulate physiological angiogenesis contributes to advances in understanding of tumoural vascularization and to the identification of potential new therapeutic targets.