Optimal concentration of human epidermal growth factor (hEGF) for epithelial healing in experimental corneal alkali wounds

Abstract

Purpose. By using bothin vivo andin vitro (organ-cultured) systems, the optimal concentrations of hEGF to enhance epithelial healing after alkali wounds were evaluated in the rabbit cornea. Methods. Alkali-injured corneas (φ = 5.5 mm, 1 N NaOH, 60 s) were treated with 0.01, 0.1, 1.0, 10 and 100 ng/ml hEGF for thein vitro study. The healing of epithelium and endothelium was determined at 1, 2, 3, 4, and 6 days after treatment. For thein vivo experiment, the eyes were treated with 2, 5, 10, and 50 mg/ml hEGF 3 times per day. The measurement of epithelial healing rate, transmission electron microscopy and immunohistochemical observation were performed after 7 days treatment. Results. In in vitro tests, hEGF enhanced the epithelial healing rates, showing a maximum enhancement at the concentration of 1.0 ng/ml, and endothelial healing was increased at 100 ng/ml. In in vivo studies, no significant difference was observed in the rates of epithelial healing between control and each hEGF-treated group. Among the tested concentrations, 5 μg/ml hEGF induced the most active proliferation of basal cells and 50 μg/ml hEGF remarkably produced a vascular ingrowth to the central wound area. The thickness of re-surfaced epithelium was increased by hEGF in a concentration-dependent manner. Conclusions. The results of the present study indicate that a low concentration of hEGF may selectively enhance epithelial healing without affecting endothelial healing. The optimal concentration of hEGF for the stimulation of epithelial healing appears to be 5 μg/ml in rabbit corneal alkali wounds.