[Transplantation of iris pigment epithelium]

Transplantation of iris pigment epithelial (IPE) cells to the subretinal space has been attempted as a therapeutic modality for the treatment of age-related macular degeneration (AMD). IPE cells are used because autologous cells are readily available and because IPE and RPE cells share a common embryonic origin, possess the capacity of transdifferentiation into other ocular cells, and share common morphological and functional characteristics. Once the technique of IPE cell transplantation was established in an animal mode, several clinical studies analyzed the behavior of IPE cell suspensions transplanted to the subretinal space of patients with AMD following surgical membrane extraction. In our experience, as well as that of other investigators, transplantation of IPE cells to the subretinal space of AMD patients prevents the recurrence of the subretinal neovascularization and stabilizes but does not improve visual acuity. Since IPE cells transplanted as a cell suspension do not appear to form a cell monolayer in the subretinal space, the transplantation of preformed IPE or RPE cell monolayers is being investigated as the development of an functional cell monolayer is mandatory if functional success, i.e., recovery of vision in AMD patients, is the ultimate goal of IPE cell transplantation.