Topical Rho kinase inhibitor rescues TRPV4 deficiency-induced an impairment of corneal epithelial wound healing by enhancing limbal stem cell proliferation

PURPOSE: Transient receptor potential vanilloid 4 (TRPV4), a mechanosensitive cation channel, is essential for cell proliferation in peripheral cornea during epithelial repair. We examined whether topical administration of a Rho kinase inhibitor, Y-27632, rescues impaired epithelial healing in TRPV4 knockout (KO) mice. METHODS: TRPV4 KO mice underwent 2 mm corneal epithelial debridement and were topically treated every 6 h with Y-27632 or PBS. Epithelial closure was monitored by fluorescein staining. Cell proliferation was evaluated by BrdU incorporation. Corneal sensitivity was assessed with a Cochet-Bonnet aesthesiometer. TKE2 cells were cultured with TRPV4 inhibitor HC-067047, with or without Y-27632, and proliferation was measured by Alamar Blue assay. RESULTS: Topical Y-27632 significantly accelerated wound closure in TRPV4 KO mice at 24 h post-debridement. The number of BrdU-positive cells was significantly more frequently observed in the peripheral, but not central, cornea of Y-27632-treated mice as compared with control mice. Corneal surface sensitivity was unchanged by topical Y-27632. Supplementation of Y-27632 upregulated TKE2 proliferation under TRPV4 inhibition-condition. CONCLUSIONS: Topical Y-27632 rescues TRPV4 deficiency-induced impairment of epithelial repair by promoting proliferation of cells in peripheral epithelium, presumably epithelial stem cells. ROCK inhibition may represent a novel therapeutic options for refractory corneal epithelial disorders.