Cytokine Gene Expression after Subretinal Transplantation

Transplantation study of neural retina, retinal pigment epithelial (RPE), or iris pigment epithelial (IPE) cells have been performed not only in animal model but in human age-related macular degeneration, and some of the findings reported with cystoid macular edema may have been due to graft rejection. In this investigation, we examined cytokine gene expression by reverse transcriptase-polymerase chain reaction at the transplanted subretinal space. Transplantation was performed in normal Royal College of Surgeon's rats using cultured human RPE and rat IPE. They were followed without immunosupression. Gene expression for melanogenesis of transplanted human RPE was observed only in the early days after transplantation. Rat interleukin (IL)-1α, -1β, -2, -6, interferon γ, and tumor necrosis factor α (TNFα) genes were also expressed after the early days of transplantation. Cytokine expression was observed not only after cell transplantation but also after vehicle-only injection, which was considered a reaction to the surgical trauma. However, statistically significant amount of expressions of IL-1α, -1β, and -6 were observed after the early days of transplantation of human RPE or IL-1α, -1β, and TNFα of rat IPE, if we compare them to vehicle-only injection. These cytokines may play an important role for the local reaction after transplantation.