Autologous Transplantation of RPE with Partial-Thickness Choroid after Mechanical Debridement of Bruch Membrane in the Rabbit

Abstract

An improved translocation technique for autologous retinal pigment epithelium (RPE) transplantation is presented. The graft consists of a sheet of a partial-thickness choroid with RPE attached. Twenty-seven pigmented rabbits were used in this study. After mechanical debridement of Bruch membrane, partial-thickness RPE-choroid sheets were transplanted onto the subretinal space in 25 rabbits. The animals were examined by fundus photographs and fluorescein angiographs and were killed postoperatively at 1, 2, 4, 12, and 24 weeks. Eyecups containing the grafts were examined by light microscopy and immunohistochemistry. In addition, two partial-thickness RPE-choroid sheets were analyzed by transmission electron microscopy (TEM). TEM revealed that the partial-thickness RPE-choroid graft consisted of retinal pigment epithelial cells, Bruch membrane, choriocapillaris, and ruptured middle vessels. The thickness of the graft was approximately 50 to 60 microm. Fluorescein angiography revealed neither fluorescein leakage nor staining in the graft at early or late phase. Light microscopy revealed that in 17 experiments in which the graft survived, the neural retina remained intact; however, in eight experiments with unsuccessful grafts, the neural retina degenerated. The surviving graft showed revascularization and monolayered retinal pigment epithelial cells. Furthermore, in sections in which the neural retina over the graft remained intact, all retinal pigment epithelial cells in the graft and rhodopsin in photoreceptor outer segments were positively labeled with anticellular retinaldehyde-binding protein antibodies and anti-opsin antibodies, respectively. A partial-thickness RPE-choroid graft showed improved integration with the host choroid and photoreceptors. This technique has the potential to be a treatment for age-related macular degeneration.