Transplantation of transduced retinal pigment epithelium in rats

PURPOSE. To examine the effects of transplanting retinal pigment epithelial (RPE) cells transduced with neurotrophic factor genes into the subretinal space of rats. METHODS. RPE cells were transduced with plasmids carrying the cDNAs of Axokine (ciliary neurotrophic factor [CNTF]; Sumitomo Pharmaceuticals Co., Ltd., Tokyo, Japan), brain derived-neurotrophic factor (BDNF), and basic fibroblast growth factor (bFGF) genes. These RPE cells were transplanted into the subretinal space of rats, and the localization was examined. The expression of enhanced green fluorescent protein (eGFP)-BDNF-transduced RPE in the subretinal space was examined by real-time polymerase chain reaction (PCR) after the transplanted cells were collected by cell sorting. The expression of major histocompatibility complex (MHC) class I and -II after gene transduction was examined by real-time PCR. The ratio of CD4⁺ and CD8⁺ T cells and antibody production against transplanted cells were analyzed by flow cytometry. RESULTS. The transplant sites were not significantly different among the neurotrophic factors tested. The RPE cells expressed the BDNF gene in the subretinal region at approximately the same level as that in vitro. RPE cells transduced with Axokine stimulated MHC-I expression, and the cell transplantation changed the ratio of CD4⁺ and CD8⁺ T cells. A significant production of antibody against the Axokine-transduced RPE cells was also observed after Axokine-transduced RPE transplantation. CONCLUSIONS. RPE cells transduced with neurotrophic factors express the factors after transplantation into the subretinal space. RPE transduced with Axokine or bFGF, in contrast to RPE transduced with BDNF, stimulate an immunologic reaction of the host.