Application of Tissue–Engineered Corneal Epithelial Cell Sheet Transplantation to Excimer Laser Keratectomy in Rabbit

Abstract

Abstract: : Purpose: Excimer laser photorefractive keratectomy (PRK) is widely used to correct refractive error. However, postoperative corneal haze is still the major problem to be resolved. In the present study, we applied our newly developed approach using tissue–engineered cell sheet transplantation to PRK in rabbits and assessed the inhibitory effect on the corneal haze. Methods: A section of limbal biopsy (5X5mm) was obtained from one eye of each rabbit. Epithelial cells were prepared and cultured on temperature–responsive culture surfaces for 2 weeks for the fabrication of a multilayered tissue–engineered epithelial cell sheet. At the time of surgery, PRK (7.0mm ablation zone and 160µm depth) was performed in the contralateral eye. Immediately after PRK, the autologous tissue–engineered cell sheet was transplanted to the corneal site receiving PRK (n=17). The 19 eyes undergoing PRK alone without cell sheet transplantation was served as control. We assessed the eyes by slit–lamp and histological examination. The corneal haze was scored in a masked fashion according to the Fantes’ grading scale by three corneal specialists. Results: The tissue–engineered cell sheets were stably attached on the laser–irradiation site during surgery and maintained, resulting in an epithelialization immediately after surgery. In contrast, epithelialization was completed for 3 to 5 days in the control group. At 1 and 2 months after surgery, corneal haze was significantly suppressed in the transplantation group compared to the control group. Histological analyses showed that number of keratocytes undergoing apoptosis was decreased in the transplantation group at 3 days after surgery, and that the accumulation of collagen type III and the number of the cells expressing α–smooth muscle actin were diminished in the transplantation group at 1 to 3 months after transplantation. Conclusions: Tissue–engineered corneal epithelial cell sheet transplantation is an effective method to suppress corneal haze after PRK.

Keywords: refractive surgery • transplantation • cornea: stroma and keratocytes