Autologous subretinal transplantation of cultured porcine iris pigment epithelium (IPE)

Background: Subretinal transplantation of pigment epithelium may be a thera peutic option for surgical treatment of age-related macular degeneration (A MD), Various experimental data have demonstrated that homologous transplant ation of retinal pigment epithelium (RPE) can prevent photoreceptor deterio ration. However, most investigators experienced immunogenic graft rejection when using homologous pigmented cells for grafting. Autologous cells were soon considered as an alternative for subretinal grafting. Particularly iri s pigment epithelium (IPE) appeared suitable to replace homologous RPE for its embryogenetic similarity and its simple availability. Recent studies ha ve shown, that IPE is capable of taking over functions of RPE in maintainin g retinal metabolism. The purpose of this study was to evaluate if autologo us IPE-cells would survive when being transplanted subretinally. In additio n, immunogenic responses to the presence of "foreign" iris pigment cells ne eded to be excluded. Materials and Methods: Iris tissue was obtained by peripheral iridectomy in the anesthetized pig. Sheets of pigmented iris epithelium were separated f rom the specimens and transferred into tissue culture. After the cells had been grown to confluency, cell suspensions were injected into the subretina l space of the donor animal's fellow eye. After 4 weeks, the grafted eye wa s enucleated and examined histologically. Results: The histological exam revealed that the grafted cells had survived in the subretinal space. No evidence of immunogenic rejection was observed . Conclusions: Autologous IPE-cells can survive in the host's subretinal spac e without creating inflammatory reactions. Transplanted IPE appears to inte ract with photoreceptor outer segments.