VEGF (vascular endothelial growth factor) is a signal protein that promotes the growth of new blood vessels. VEGF forms part of the system that restores the blood supply to cells and tissues when they are deprived of oxygenated blood due to compromised blood circulation.
VEGF proteins form a particular sub-family of growth factors referred to as the platelet-derived growth factor family of cystine-knot growth factors. They are key signalling proteins involved in two different types of blood vessel formation, namely vasculogenesis and angiogenesis. Vasculogenesis refers to the de novo formationof vessels in the development of the embryo’s circulatory system, while angiogenesis describes the formation of blood vessels from vasculature that already exists.
The most important member of the VEGF family is VEGF-A. Other factors in the family include VEGF-B, VEGF-C, VEGF-D and placenta growth factor (PlGF). Other VEGF related proteins include VEGF-E encoded by viruses and VEGF-F found in the venom of some snakes.
The different roles of the various VEGF proteins are described below:
- VEGF-A – VEGF-A is required for angiogenesis, specifically for the creation of the blood vessel lumen and fenestrations; for promoting the migration and mitosis of endothelial cells, and stimulating matrix metalloproteinase and αvβ3 activity. This protein is also chemotactic for granulocytes and macrophages and stimulates vasodilation through the release of nitric oxide.
- VEGF-B – This protein is required for blood vessel formation in the embryo (embryonic angiogenesis).
- VEGF-C – This protein is key to the formation of new lymphatic vessels from those already existing.
- VEGF-D – This form of VEGF is required for the development of lymphatic vessels that surround the bronchioles or air passages within the lungs.
- PlGF – This form of VEGF is required for vasculogenesis and angiogenesis.