Purpose: To determine whether vascular endothelial growth factor and basic fibroblast growth factor, which may be critical mitogens for neovascularization, are present together in human retinal and choroidal neovascular membranes.
Methods: Light microscopic immunocytochemistry using antibodies against vascular endothelial growth factor, basic fibroblast growth factor, and several cellular "marker" proteins on frozen sections from three choroidal neovascular membranes from patients with age-related macular degeneration, seven surgically excised epiretinal membranes from patients with proliferative diabetic retinopathy, and six epiretinal membranes from patients with nonischemic proliferative retinopathies.
Results: All three choroidal neovascular membranes and all seven epiretinal membranes stained positive for vascular endothelial growth factor. Two choroidal neovascular membranes and six of the epiretinal membranes were positive for basic fibroblast growth factor. The same cells were often positive for both antigens. None of the epiretinal membranes from patients with nonischemic proliferative retinopathies were positive for either growth factor. Many of the cells that demonstrated growth factors were glial cells, vascular endothelial cells, and retinal pigment epithelial cells.
Conclusions: Colocalization of two growth factors in the same cells of ocular neovascular membranes suggests that more than one growth factor may contribute to pathologic angiogenesis. Growth factors in neovascular tissues are not localized exclusively in the vascular endothelium. Because expression of some growth factors is stimulated by hypoxia, their localization within choroidal neovascular membranes suggests that hypoxia may be an etiologic factor for choroidal as well as for retinal neovascularization.