Abstract
Abstract: :
Purpose: We chose a non viral gene transfer method to correct the RPE phagocytic deficiency by replacement of the lacking c-mer tyrosine kinase receptor which is responsible for the RCS retinal degeneration. Methods: Our plasmid-enhanced cationic-lipid transfection system was used to introduce the normal c-mer cDNA in deficient RPE cells. We performed subretinal injections of isolated liposomes, native pIRES EYFP or c-mer/pIRES EYFP plasmids complexed to cationic liposomes in 18 days old RCS rats. ERG recordings, fluorescent EYFP transgene expression tests by slide-mounted RPE and c-mer protein expression tests by immunohistochemistry were performed each week during 2 months post-injection. Results: The injection area represents almost 30 % of a whole retina. In this area 50 % to 75 % of the cells were transfected. The EYFP transgene was observed in RPE cells under fluorescent microscopy until 5 weeks after injection, with a gradual decrease of the fluorescent cells number and of the fluorescence intensity. A delay in the a-wave ERG measurement decrease was observed in RCS rats injected with the c-mer plasmid DNA:liposome complexes compared to controls. We detected a consistent effective c-mer protein expression only in RCS RPE cells of the injected area on paraffine eye sections simultaneously with the EYFP transgene expression. Conclusion: The RCS photoreceptor degeneration has been significantly delayed both morphologicaly and electrophysiologicaly loss of activity by restoring the phagocytic capability of RCS deficient RPE cells. The lack of immunological response following the non viral gene transfer method used in this study deserves to be considered as an interesting alternative for the treatment of inherited retinal degenerations. CR : None Support : this work was sponsored by Association Rétina France and Fondation pour la Recherche Médicale.
Keywords: 554 retina • 316 animal model • 580 signal transduction