Corneal endothelial dysfunction accompanied by visual disturbance is a primary indication for corneal transplantation. We previously reported that the adhesion of corneal endothelial cells (CECs) to a substrate was enhanced by the selective ROCK inhibitor Y-27632. It is hypothesized that the inhibition of ROCK signaling may manipulate cell adhesion properties, thus enabling the transplantation of cultivated CECs as a form of regenerative medicine. In the present study, using a rabbit corneal endothelial dysfunction model, the transplantation of CECs in combination with Y-27632 successfully achieved the recovery of corneal transparency. Complications related to cell injection therapy, such as the abnormal deposition of the injected cells as well as the elevation of intraocular pressure, were not observed. Reconstructed corneal endothelium with Y-27632 exhibited a monolayer hexagonal cell shape with a normal expression of function-related markers, such as ZO-1, and Na(+)/K(+)-ATPase, whereas reconstruction without Y-27632 exhibited a stratified fibroblastic phenotype without the expression of markers. Moreover, transplantation of CECs in primates in the presence of the ROCK inhibitor also achieved the recovery of long-term corneal transparency with a monolayer hexagonal cell phenotype at a high cell density. Taken together, these results suggest that the selective ROCK inhibitor Y-27632 enables cultivated CEC-based therapy and that the modulation of Rho-ROCK signaling activity serves to enhance cell engraftment for cell-based regenerative medicine.

The inhibition of Rho/ROCK signaling by specific ROCK inhibitor Y-27632 promoted the adhesion of MCECs, inhibited apoptosis, and increased the number of proliferating cells. These results suggest that the ROCK inhibitor may serve as a new tool for cultivating HCECs for transplantation.

Citation: Okumura N, Koizumi N, Kay EP, et al. The ROCK inhibitor eye drop accelerates corneal endothelium wound healing. Invest Ophthalmol Vis Sci. 2013;54:243954: -250254: . DOI:10. 1167 PURPOSE. To evaluate the effect of Rho kinase (ROCK)-inhibitor eye drops on a corneal endothelial dysfunction primate model and human clinical case series of corneal endothelial dysfunction.METHODS. As a corneal-endothelial partially injured model, the corneal endothelium of seven cynomolgus monkeys was damaged by transcorneal freezing; 10 mM of ROCK inhibitor Y-27632 was then applied topically 6 times daily. The phenotype of the reconstructed corneal endothelium was evaluated by immunohistochemical analysis and noncontact specular microscopy. For clinical study, the effect of Y-27632 eye drops after transcorneal freezing was evaluated in eight corneal endothelial dysfunction patients: four central corneal edema patients and four diffuse corneal edema patients.RESULTS. Slit-lamp microscopy revealed that both Y-27632-treated and -nontreated corneas became hazy after transcorneal freezing, and then recovered their transparency within 4 weeks. ROCK inhibitor Y-27632 promoted recovery of corneal endothelial cell density and wound healing in terms of both morphology and function. The percentage of ZO-1 and Na þ / K þ -ATPase positive cells in the regenerated area in the Y-27632 group was significantly higher than in the controls. Noncontact specular microscopy revealed that corneal endothelial cell density was significantly higher in the Y-27632 group compared with the controls at 4 weeks; cell density reached approximately 3000 cells/mm 2 , as opposed to 1500 cells/mm 2 in the control group. In addition to the animal study findings, the clinical study findings showed that Y-27632 eye drops effectively improved corneal edema of corneal endothelial dysfunction patients with central edema. 2 However, several severe problems can arise associated with corneal transplantation, including allograft rejection, primary graft failure, and severe loss of cell density. To the best of our knowledge, no clinically practical medical therapy has been developed to effectively treat corneal endothelial dysfunction.As an alternative to corneal transplantation, regenerative medical procedures might be a plausible path of therapy for treating severe corneal endothelial dysfunction. Several research groups, including ours, have reported transplantations of cultivated CECs in an animal model to establish a new clinical intervention for corneal endothelial dysfunction. [3][4][5][6][7][8][9] We recently reported the use of cell therapy to successfully achieve the recovery of corneal transparency in both rabbit and primate corneal endothelial dysfunction models. 9 However, in cases of early-stage corneal endothelial dysfunction, in which stem cells or progenitor cells are still maintained in the tissue, drug therapy may provide a less-invasive or antiprogression treatment. Our group, as well as several other groups, reported that pharmaceutical agents such...

A model of cultivated corneal endothelial transplantation for corneal endothelial dysfunction was established in primates whose corneal endothelial cells have less proliferative capacity in vivo. Our results suggest that this is a useful model for long-term observation in advance of the future clinical application of cultivated corneal endothelial transplantation.

The corneal endothelium maintains corneal transparency; consequently, its dysfunction causes severe vision loss. Tissue engineering-based therapy, as an alternative to conventional donor corneal transplantation, is anticipated to provide a less invasive and more effective therapeutic modality. We conducted a preclinical study for cell-based therapy in a primate model and demonstrated regeneration of the corneal endothelium following injection of cultured monkey corneal endothelial cells (MCECs) or human CECs (HCECs), in combination with a Rho kinase (ROCK) inhibitor, Y-27632, into the anterior chamber. We also evaluated the safety and efficacy of Good Manufacturing Practice (GMP)-grade HCECs, similar to those planned for use as transplant material for human patients in a clinical trial, and we showed that the corneal endothelium was regenerated without adverse effect. We also showed that CEC engraftment is impaired by limited substrate adhesion, which is due to actomyosin contraction induced by dissociation-induced activation of ROCK/MLC signaling. Inclusion of a ROCK inhibitor improves efficiency of engraftment of CECs and enables cell-based therapy for treating corneal endothelial dysfunction as a clinically relevant therapy.