Distribution of growth factors in subfoveal neovascular membranes in age-related macular degeneration and presumed ocular histoplasmosis syndrome.

PURPOSE: We performed a histopathologic and immunohistologic study to determine the macromolecular and cellular components of subfoveal neovascular membranes removed at the time of submacular surgery.

METHODS

Subfoveal neovascular membranes were surgically removed from ten patients (seven with age-related macular degeneration and three with presumed ocular histoplasmosis syndrome). Tissues obtained were examined by light and electron microscopy to identify structural components. Immunohistochemical staining was then performed with monoclonal antibodies to various growth factors, including transforming growth factor-beta 1, basic fibroblast growth factor, platelet-derived growth factor, and epidermal growth factor, as well as antibodies against procollagen 1 and phosphotyrosine residues.

RESULTS

Most cells in subfoveal neovascular membranes are retinal pigment epithelial cells and cells resembling fibroblasts, with some vascular endothelial cells, lymphocytes, and macrophages. Basic fibroblasts growth factor was found in the extracellular matrix and in endothelial cells. Transforming growth factor-beta 1 was found in endothelial cells, fibroblasts, and retinal pigment epithelial cells. Procollagen 1 was found in protein-synthesizing fibroblasts, and phosphotyrosine residues were detected within fibroblasts, endothelial cells, and retinal pigment epithelial cells.

CONCLUSIONS

Subfoveal neovascular membranes are neovascular complexes composed of retinal pigment epithelial cells, fibroblasts, vascular endothelial cells, and chronic inflammatory cells. Furthermore, transforming growth factor-beta 1 and basic fibroblast growth factor are present within the major cell types, which suggests a possible pathogenic role in the development of the neovascular complex.