Basic, not acidic fibroblast growth factor stimulates proliferation of cultured human retinal pigment epithelial cells.

PURPOSE In this study, we evaluated a possible effect of acidic and basic fibroblast growth factor (aFGF, bFGF) on the proliferation of human retinal pigment epithelial (RPE) cells in culture. As the RPE is the primary source for bFGF in the retina, such an effect would suggest autocrinic actions of FGFs. METHODS Primary cultures of human and porcine RPE and an established human RPE cell line (D407) were subjected to aFGF and bFGF at different culture conditions. Cell proliferation was determined using the BrdU non-radioactive nucleotide analogue assay, and total protein was measured colorimetrically. The cells were subjected to aFGF and bFGF from 0.1 to 100 ng/ml for 1 to 14 days. RESULTS In the presence of 100 ng/ml bFGF, cell proliferation doubled from day 2 (143+/-12 units) to day 6 (227+/-17). This effect was neither seen without bFGF nor with aFGF at the same concentration. The stimulating effect of bFGF on cell proliferation was dose-dependent, the ED50 being around 1-10 ng/ml. The bFGF effect was markedly greater at high fetal calf serum concentration (10% vs. 1%). No bFGF effect was seen on cells of the established human RPE cell line D407 nor on primary cultures from porcine RPE. CONCLUSIONS bFGF, in contrast to its analogue aFGF, stimulates cell proliferation in cultured human RPE cells. It may act as an autocrinic agent (secretion by and action on the same cell) and thus be a specific regulator for cell proliferation in repair and replacement of the RPE cell monolayer.