Protective Effect of Hyaluronic Acid on the Corneal Endothelial Function Against Free-Radical Damage

ABSTRACT

PURPOSE: To investigate the protective effects of hyaluronic acid with glutathione and ascorbic acid on corneal endothelial function against free-radical damage. METHODS: bovine corneal endothelial(BCEN) cells were treated with a flux of chemically generated superoxide anion produced by the combination of 1 mM hypoxanthine and 0.06 U/ml xanthine oxidase(HX-XO) for 10 minutes, and rabbit corneas were mounted in the dual-chamber specular microscope and perfused with bicarbonate Ringer(BR) solution for one hour and their endothelial surface was exposed to HX-XO for five minutes, and then perfused with glutathione, hyaluronic acid, or ascorbic acid in BR solution for three hours. BCEN cells was observed using MTT assay and rabbit corneal thickness was measured every 15 minutes and corneal swelling rates were calculated by linear regression analysis. Also, corneal endothelial permeability was measured using carboxyfluorescein and fluorometer. RESULTS: MTT assay showed less cytotoxicity in the cells treated with glutathione, hyaluronic acid, or ascorbic acid compared to HX-XO alone. Glutathione, hyaluronic acid, or ascorbic acid reduced the rabbit corneal swelling caused by HX-XO. Corneal endothelial permeability(Pac) increased in corneas perfused with HX-XO(7.88 x 10 cm/min) while those with BR had Pac of 4.54 x 10 cm/min. Following treatment with glutathione, hyaluronic acid, or ascorbic acid, Pac decreased to 4.96, 6.81, and 5.25 respectively(p<0.05). CONCLUSIONS: In conclusion, these data suggest that hyaluronic acid scavenges HX-XO-generated oxyradicals as well as glutathione and less likely ascorbic acid.