Protection of Photoreceptor Cells from Phototoxicity by Subretinal Transplantation of Iris Pigment Epithelial Cells Transduced with Adeno–associate Virus–mediated Brain–derived Neurotrophic Factor Gene

Abstract

Abstract: : Purpose:To evaluate the effect of subretinal transplantation of iris pigment epithelial (IPE) cells transduced with adeno–associated virus (AAV2)–mediated brain–derived neurotrophic factor (BDNF) gene against phototoxicity. Methods:The BDNF gene was inserted into AAV2 (AAV2–BDNF) and the recombinant AAV2 was transduced into rat IPE (AAV2–BDNF–IPE) cells with variable multiplicity of infection (MOI). The AAV2–BDNF–IPE cells were transplanted into the subretinal space of rats, and the rats were placed under constant light on days 1 and 90 after the transplantation. The thickness of the outer nuclear layer was measured histologically and compared with those of rats transplanted with AAV2–beta–galactosidase gene (LacZ)–IPE cells, with non–transduced IPE cells, or with vehicle injection. The amount of AAV capsids and BDNF was determined by enzyme–liked immunosorbent assay (ELISA). Results:The transduction efficiency, determined by infectious center assay, was about 8%, and the transduced IPE cells had 27 pg BDNF/mg protein at MOI of 5. The transduction efficiency seemed to increase as successive culture. A statistically significant photoreceptor protection was observed in eyes transplanted with AAV2–BDNF–IPE on days 1 and 90. LacZ expression was observed in the subretinal space even 90 days after transplantation, and local inflammation was not present. Conclusions:Transplantation of AAV2–BDNF–IPE cells may be an alternative method of delivering the target gene to the lesion, although the transduction efficiency was less than 10%.

Keywords: iris • neuroprotection • gene transfer/gene therapy