Vascular endothelial growth factor, or VEGF, is a molecule which is involved in the formation of blood vessels. It stimulates cells to divide and change, and is important in blood vessel development in the embryo, wound repair, muscle formation and bypassing of vessel blockages. Sometimes vascular endothelial growth factor becomes involved in abnormal blood vessel development, which occurs during the growth of cancers. Abnormal blood vessel growth is associated with a number of diseases including macular degeneration, where sight can be lost. Understanding of factors such as VEGF, and the creation of drugs which affect their actions, may help to treat such illnesses.
VEGF is what is referred to as an angiogenic growth factor. Angiology is the study of blood vessels, and the process by which new ones are created is known as angiogenesis, so an angiogenic substance is something which encourages blood vessels to form. When angiogenesis occurs in association with existing blood vessels, angiogenic growth factors such as VEGF attach themselves to special receptors on the cells that line blood vessels. They stimulate the cells to produce enzymes that dissolve the membrane to which they are fixed, creating openings. The cells then divide and move through these openings to form a new branch of the blood vessel, while different enzymes break down the tissue surrounding it, making space for its growth.
When blood vessel formation goes out of control, there may be a lack of angiogenic growth factor, leading to a deficiency of blood vessels and insufficient blood supply to tissues, causing cells to die. This occurs in conditions such as stroke and heart disease. Too much angiogenic growth factor causes an overgrowth of vessels, which may supply diseased tissues while damaging healthy ones. Excessive blood vessel formation is found in diseases including psoriasis, hyperthyroidism, cancer, diabetic eye disease and macular degeneration.
VEGF has been used to treat macular degeneration, a disease where the blood vessels in the eye grow abnormally, eventually destroying a person's sight. Cells in the retina become starved of oxygen, so vascular endothelial growth factor causes new blood vessels to grow, but these are defective and the area of central vision ends up scarred and unable to function. Drugs have been developed which are injected into the eye and which stop vascular endothelial growth factor from attaching to the receptors on blood vessels, where it would normally stimulate growth.
A number of diseases can be treated by making use of the properties of vascular endothelial growth factor. It may be used directly, to increase blood vessel formation and the blood supply to damaged tissues found in wounds or heart disease. Alternatively, drugs can be targeted against it, inhibiting its function and suppressing blood vessel growth in diseases such as cancer.
