EX VIVO EXPANSION OF RPE CELLS FOR TRANSPLANTATION

Retinal pigment epithelial cells (RPE) play a pivotal role in maintaining retinal function. Dysfunction of RPE contributes to the pathogenesis of age-related macular degeneration (ARMD), which accounts for the major cause of permanent visual loss after age 55 years in Western countries. Conventional treatment such as laser photocoagulation has a limited success and photodynamic treatment remains palliative. One exciting and potentially curative treatment is subretinal transplantation of healthy RPE. Our preliminary studies showed that growth and proper differentiation of rabbit RPE can be promoted by cryopreserved human amniotic membrane (AM) in culture. Thus we envision to establish new RPE transplantation by including Step 1: Transvitreal Biopsy to Harvest Autologous RPE; Step 2: Ex Vivo Expansion of Harvested RPE on AM; and Step 3: Subretinal Transplantation of Expanded RPE with AM. In the Phase I SBIR, we propose to resolve key elements of these three steps. Aim 1: In Step 2, we would like to establish a reproducible protocol for culturing rabbit RPE on human AM by determining the minimal seeding density needed to maintain normal morphology and phenotype during ex vivo expansion. Aim 2: In Step 1, we would like to establish a reproducible protocol for performing transvitreal biopsy so that sufficient numbers of RPE can be obtained to match the seeding density established in Aim 1. Aim 3: In Step 3, we would like to establish a reproducible procedure of implanting human AM with RPE into the subretinal space in rabbits. Completion of these three Aims will allow us to launch a pre-clinical study in rabbits to demonstrate the safety and eficacy of transplanting such ex vivo expanded autologous RPE together with AM to the rabbit's subretinal space and maintaining normal RPE morphology and functions after transplantation during Phase II SBIR. Success in accomplishing these goals will allow us to engineer this new tissue-based "Biologies" to restore sights in patients suffering ARMD or other retinal diseases in which RPE is dysfunctional.