Experimental transplantation of autologous iris pigment epithelial cells to the subretinal space

Purpose: To investigate the cellular morphology in the subretinal space fol lowing transplantation of iris pigment epithelial (IPE) cells from the same eye. Methods: Following an iridectomy, fresh IPE cells were prepared and no cult uring performed. After pars plana vitrectomy, a suspension of autologous IP E cells was injected into the subretinal space in 37 rabbits. The grafts we re monitored by ophthalmoscopy and colour fundus photography. Rabbits were sacrificed at 1, 2, 3 and 6 months, respectively, and the eyes examined wit h fight and electron microscopy. Results: The grafted area retained the same configuration over 6 months but then appeared less pigmented. At 1-3 months, the IPE formed one or more co ntiguous layers on top of native RPE. At 6 months, cells compatible with gr afted IPE were present in the subretinal space, often forming monolayer-lik e chains integrating with the native RPE. Depigmented cells of presumed IPE origin were seen and frequently in association with abundant melanin granu les located in the apical portion of adjacent RPE cells. In such areas, lar ge macrophage-like cells were observed. Conclusion: Transplanted IPE cells survived for up to 6 months in the subre tinal space. Our observations suggest a scenario of remodelling of the cell ular layers in the subretinal space over time where grafted IPE cells forme d a compound layer with the native RPE. Transplantation of autologous IPE c ells may have a potential as a treatment modality in selected cases of age- related macular degeneration.