VEGF in Non-Murine Animal Models of Normal Physiological Processes and Disease

Angiogenesis is a dynamic process that results in the formation of new blood vessels from pre-existing vasculature. This process is regulated by a host of proand anti-angiogenic factors (Iruela-Arispe 1997). When there is an imbalance favoring pro-angiogenic stimuli, the angiogenic switch is thrown (Bergers 2003). Blood vessels dilate and become leaky, pericytes that surround and support mature blood vessels loosen their connections, and the vasculature basement membrane and extracellular matrix is degraded by proteases allowing endothelial cells to proliferate and migrate towards the angiogenic stimuli. As endothelial cells migrate through the angiogenic gradient, they adhere together in a tube structure and a lumen is formed. Pericytes then migrate and stabilize the new vessel. One of the most potent stimulators of blood vessel growth is vascular endothelial growth factor (VEGF) (Ferrara 1997).