Vascular endothelial growth factor (VEGF) is a signal protein required for the formation of new blood vessels. Proteins from this family play important roles in various bodily process such as inflammation and wound healing, as well as contributing to disease processes when they are overexpressed.
Some of the roles played by VEGF are described below:
- One of the main functions of VEGF is to form new blood vessels as a baby grows and develops within the womb. This protein also stimulates the growth of new blood vessels after injury and the growth of muscle after exercise has been performed.
- In cases where blood vessels are obstructed, VEGF also promotes the creation of new blood vessels to bypass the blocked vessels
- The overexpression or underexpression of VEGF is a contributing factor to the development of disease. For example, solid tumors require an increased blood supply if they are to continue growing beyond a certain size and tumors that express VEGF are able to continue growing because they can develop this enhanced blood supply, a process referred to as angiogenesis. Cancers that express VEGF are therefore able to grow and spread (metastasize) to other organs and regions of the body.
- In rheumatoid arthritis, VEGF is released in response to the presence of TNF-α. This increases inflammation, endothelial permeability and angiogenesis.
- VEGF plays a role in the development of diabetic retinopathy. Poor circulation in the tiny retinal blood vessels can lead to ischemia, which causes increased expression of the pro-angiogenic form of VEGF. This leads to the formation of new blood vessels in the retina which can cause visual disturbances.
- VEGF is also a contributing factors in the wet form of age-related macular degeneration (AMD), a major cause of blindness in elderly people. The pathology is similar to that seen with diabetic retinopathy.
- A decreased level of VEGF in the pulmonary arteries has been associated with the condition pulmonary emphysema.
- The overexpression of VEGF in the kidney has been found to cause glomerular hypertrophy, which is associated with excess protein in the urine (proteinuria).
- Changes in levels of VEGF have also been associated with the onset of pre-eclampsia in pregnancy.
Two drugs that have been successful at slowing the progression of disease due to VEGF are monoclonal antibodies bevacizumab and ranibizumab.