Effect of the Rho-Associated Kinase Inhibitor Eye Drop (Ripasudil) on Corneal Endothelial Wound Healing.

PURPOSE Ripasudil (Glanatec), a selective rho-associated coiled coil-containing protein kinase (ROCK) inhibitor, was approved as a glaucoma and ocular hypertension treatment in Japan in 2014. The purpose of this study was to investigate the feasibility of using ripasudil eye drops to treat corneal endothelial injuries. METHODS Cultured human corneal endothelial cells (HCECs) were treated with ripasudil, and 5-bromo-2'-deoxyuridine (BrdU) incorporation was evaluated by ELISA. A rabbit corneal endothelial damage model was also created by mechanically scraping the corneal endothelium, followed by topical ripasudil eye drop application for 2 weeks. The anterior segment was evaluated by slit-lamp microscopy, and central corneal thickness was measured by ultrasound pachymetry. Corneal specimens were evaluated by phalloidin staining and immunohistochemical analysis using antibodies against Ki67, N-cadherin, and Na+/K+-ATPase. RESULTS Many more BrdU-positive cells were observed among the HCECs treated with ripasudil (0.3-30 μM) than among the control HCECs. Ripasudil-treated eyes in a rabbit model showed 91.5 ± 2.0% Ki67-positive cells after 48 hours, whereas control eyes showed 52.6 ± 1.3%. Five of six corneas became transparent in ripasudil-treated eyes, whereas zero of six corneas became transparent in the control eyes. Regenerated cell densities were higher in the eyes treated with ripasudil than in eyes treated with vehicle. Eyes treated with ripasudil expressed N-cadherin and Na+/K+-ATPase in almost all CECs, whereas this expression was decreased in control eyes. CONCLUSIONS Ripasudil promoted corneal endothelial wound healing, supporting its development as eye drops for treating acute corneal endothelial damage due to eye surgeries, especially cataract surgery.