Hyaluronan-induced stimulation of corneal wound healing is a pure pharmacological effect

The aim of this study was to evaluate whether corneal reparative activity of hyaluronan is a concentration-dependent phenomenon. Corneal blocks from rabbit eyes were cultured for 20 hours with hyaluronan in different concentrations and molecular weight ranges. In another experiment, the corneal epithelium was denuded and hyaluronan was administered as eye drops. Distances of epithelial migration increased over exposed stroma proportionally to concentration, when hyaluronan was added with a molecular weight of 800-1,400 kD. Maximum effect was observed with 0.2% hyaluronan concentration. No difference was seen when corneal blocks were cultured with hyaluronan 0.2% in different molecular weight ranges (800-1,400, 1,400-2,000, and 2,000-2,600 kD). When hyaluronan (molecular weight, 800-1,400 kD) eye drops were administered after corneal epithelial denudation in rabbits, it was found to have faster wound reparation. This effect was concentration-dependent. The 2 highest concentrations (0.2% and 0.4%) were not different for the time needed to complete wound healing. In conclusion, hyaluronan-induced stimulation of corneal wound healing fulfills standards for being considered as a pharmacological effect.