الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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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).