Evidence of the presence of a specific vascular endothelial growth factor in fetal bovine retina.

The presence of a vascular endothelial cell growth factor (VEGF) in the retina was reported in a previous study. The present experiments show that VEGF exhibits a pronounced synergism with the serum-derived factor and the vascular endothelium (VE) effectors in stimulating the proliferation of vascular VE cells. VEGF shows a chromatographic multiplicity with the 25,000-D component as the smallest subunit. Mg2+ is the specific divalent cation that retains the VEGF molecule in the aggregated form and enhances the activity, both total and specific. In addition, VEGF is highly specific for endothelial cells and is distinctly different from FGF, EGF, and insulin in terms of molecular weight (MW) and cell specificity. Under our assay conditions, VEGF has no stimulatory effect on other cell lines examined, including lens epithelial cells, corneal epithelial cells, corneal keratocytes, Walker 256 carcinoma, and fibroblasts. These findings indicate that VEGF possesses characteristic properties not reported for other growth factors, and that VEGF is distinctly different from the growth factors isolated from the retina in other laboratories. The present study suggests that VEGF in the retina represents a new type of growth factor. The need to employ a highly defined assay condition could have eluded the detection of this factor in other laboratories.