Background: Although the choroidal neovascularization (CNV) is a common pathologic feature of a number of different eye diseases, its pathological mechanisms have not been fully elucidated. We investigated the expression of vascular endothelial growth factor (VEGF) in CNV using an experimental primate model.
Method: CNV was induced by intense laser photocoagulation in four monkey eyes. Single eyes were enucleated at 1, 3, 7 or 14 days after photocoagulation and examined immunohistochemically for VEGF, macrophage antigen, von Willebrand factor and glial fibrillary acidic protein (GFAP). Expression of VEGF mRNA was examined by in situ hybridization.
Results: One day after photocoagulation, the normal structure of the outer portion of the retina and the inner portion of the choroid was destroyed. Three days after photocoagulation, choroidal vascular endothelial cells migrated into the subretinal space through the defect in Bruch's membrane. Increased expression of VEGF was detected in the accumulating macrophages, migrating retinal pigment epithelial (RPE) cells and Müller cells. Maximal expression of VEGF was observed between 3 and 7 days after wounding, and many newly formed vessels extended into the subretinal space 7-14 days after photocoagulation.
Conclusion: VEGF derived from RPE cells, macrophages and Müller cells may play a role in the formation of CNV.