الفهرس | Only 14 pages are availabe for public view |
Abstract The process of new blood vessel formation is crucial in normal physiologic development and wound healing as well as in disease pathogenesis Angiogenesis is a multistep process which requires four basic steps. First endothelial precursor cells, which are likely derived from hematopoietic stem cells must be recruited to the site of vessel formation. Second, preexisting blood vessel walls and extracellular matrix must be broken down or modified to allow budding of vessels. Third , endothelial cells must be able to proliferate and migrate into the new vascular network. Finally, the new vessels must mature through addition of other cell types such as pericytes. This series of events is controlled by the proangiogenic actions of a number of diffusible extracellular matrix proteins, membrane receptors, and intracellular signal transduction molecules Vascular endothelial growth factor (VEGF) has emerged as one of the most important players in angiogenesis. There is actually a family of VEGF proteins including VEGF – A VEGF – B VEGF – C VEGF – E and placental growth factor. The main isoform involved in angiogenesis is VEGF- A Angiogenesis and vascular leakage in the eye are major pathogenic causes of visual loss and blindness in the western world. The two most important forms of ocular angiogenesis, is retinal, and subretinal (or choroidal) neovascularization In ophthalmology. a large number of VEGF antagonists is in clinical development such as bevacizumab (Avastin), ranibizumab (Lucentis) pegaptanib (Macugen). |