The Role of EG-VEGF in the Regulation of Angiogenesis in Endocrine Glands

The cardiovascular system is the first organ system todevelop and reach a functional state in an embryo(Hamilton et al. 1962). The initial steps in blood vesseldevelopment consist of vasculogenesis, the differentiation of endothelial cell precursors, the angioblasts, fromthe hemangioblasts (Risau and Flamme 1995). The juvenile vascular system evolves from the primary capillaryplexus by subsequent pruning and reorganization of endothelial cells in a process called angiogenesis (Risau1997). More recent evidence suggests that incorporationof bone-marrow-derived endothelial precursor cells contributes to the growing vessels, complementing thesprouting of resident endothelial cells (Asahara et al.1997; Rafii et al. 2002). The development of a vascularsupply is also essential in the adult for wound healing andreproductive functions (Folkman 1995). In addition, angiogenesis is implicated in the pathogenesis of a varietyof proliferative disorders: age-related macular degeneration, proliferative retinopathies, tumors, rheumatoidarthritis, and psoriasis (Garner 1994; Folkman 1995). Theprocess of angiogenesis has therefore become the focusof a variety of strategies to increase or create new vascular supply, reduce vascular damage, or compromise in order to preserve functional tissue in ischemic disease, butalso, conversely, to develop means of inhibiting angiogenesis in other pathological conditions associated withinappropriate growth, including cancer...