Retroviral Gene Transfer into Retinal Pigment Epithelial Cells Followed by Transplantation into Rat Retina

Abstract

In this preliminary report, we describe a technique for gene transfer into the retina using a retrovirus vector. We transferred the bacterial LacZ gene and the neomycin-resistance gene into pigmented wild-type rat retinal pigment epithelial (RPE) cells in culture. The RPE culture was exposed to retrovirus, and infected cells were selected with a neomycin analog (G418). The LacZ gene product was detected by X-Gal histochemistry in 95–100% of drug-resistant cells. These genetically labeled cells were transplanted into the subretinal space of two 15- to 25-day-old albino RCS rats, which have an inherited retinal degeneration syndrome. The retinas were fixed and stained with X-Gal at 3 and 6 weeks after transplantation. At both time points, pigmented, LacZ-containing cells were seen in the subretinal space. Further, there were several rows of photoreceptor nuclei in the transplant area of the approximately 2-month-old rats, while in the control contralateral eye the photoreceptor nuclei were virtually absent, as for untreated animals, suggesting that the transplanted LacZ-marked, wild-type RPE cells may have helped preserve photoreceptors. The technique for gene transfer into RPEs followed by transplantation thus provides a means for gene therapy in organisms with a genetic defect in RPE cells.

Overview summary

Previous studies have demonstrated the potential for retroviral gene transfer into retinal pigment epithelial (RPE) cells in culture. Other studies have shown that cultured RPE cells can be transplanted into the rat retina. In this preliminary study, Dunaief et al. combine these two findings and suggest that genetically modified RPE cells grown in culture can be transplanted into the rat retina, thus providing a model for gene therapy into the retina.