Purpose. Previously we have shown that bovine choroidal microvascular endothelial cells exhibit in vitro expression of FGF-5 at the mRNA and protein levels. The purpose of this study was to investigate the possible biological roles of FGF-5 for cell types involved in the process of choroidal neovascularization. Methods. The mitogenic activity of commercially obtained human recombinant FGF-5 was examined using a cell counting-based proliferation assay. A variety of cell types including bovine choroidal microvascular endothelial, fetal bovine heart endothelial, bovine aortic endothelial, human umbilical vein endothelial, Balb/c3T3 fibroblasts, and human retinal pigment epithelial (RPE) cells were tested. Balb/c3T3 cells were used as a cell line which is known to respond mitogenically to the commercial preparation of FGF-5. Basic FGF served as a positive mitogenic control for all cell lines. Results. Balb/c3T3 fibroblasts exhibited a mitogenic response to FGF-5 with an approximate ED50 of 1.8-3.7 nM which is within the range reported by the manufacturer using a similar embryonic fibroblast cell line. FGF-5 was also found to stimulate proliferation of RPE cells. Basic FGF displayed mitogenic activity for all cell lines tested with ED50's ranging from 2-100 pM. Human recombinant FGF-5 was not mitogenic for any of the endothelial cell lines tested. Conclusions. Human recombinant FGF-5 does not appear to be a mitogen for endothelial cells in vitro. This commercially prepared FGF-5 lacks carbohydrate modification found in the protein produced by eukaryotic cells. Our current studies are focused on the role which glycosylation may play in stabilizing FGF-5 and thus the biological activity of this protein. We are also investigating the possibility that FGF-5 is chemotactic in vitro without being mitogenic for these cells. FGF-5 could also be serving a strictly paracrine role in the stimulation of fibroblasts and/or RPE cells during the formation of choroidal neovascular membranes.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
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