Recombinant human epidermal growth factor and corneal neovascularization.

With a view toward possible future clinical application, we investigated whether recombinant human epidermal growth factor (hEGF) could induce corneal neovascularization. Ethylene-vinyl-acetate copolymer slow-release pellets containing either 250 ng, 500 ng or 1 microgram of hEGF or 250 ng of bovine serum albumin (BSA) were implanted into rabbit corneal stroma, and the corneas were examined by slitlamp biomicroscope for 3 weeks. The results indicated that less than 1 microgram of hEGF per pellet did not induce neovascularization in the cornea. However, when pellets containing 250 ng of basic fibroblast growth factor (bFGF) were implanted, corneal neovascularization toward these pellets occurred within 10 days. The same phenomenon occurred toward the 250 ng hEGF pellets embedded in the ipsilateral or contralateral cornea of the same animal, but was significantly less severe. When a pellet containing 250 ng bFGF was intramuscularly implanted in the animal's back, similar neovascularization was observed toward the pellets containing hEGF implanted in the same animal's cornea, but not toward implanted pellets containing BSA. These results suggest that less than 1 microgram of hEGF cannot initiate corneal angiogenesis, but can promote new vessel formation if the limbal vasculature is activated by a sprouting signal from a certain substance as trace amounts of bFGF.