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C. Kostic, A.-P. Bemelmans, M. Samardzija, M. Tekaya, D. Wanner, A. Wenzel, Y. Arsenijevic; RPE65 Lentivirus-Mediated Gene Therapy in Rpe65R91W Mouse Model Improves Cone Survival. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1981.
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© ARVO (1962-2015); The Authors (2016-present)
Gene therapy application to human patients having now started for the treatment of eye diseases, it is of prime importance to precisely document the natural history of candidate diseases for this strategy. Patients suffering from Leber's Congenital Amaurosis (LCA) display a high heterogeneity in the time course of their visual loss, and mouse model technologies offer interesting possibilities to mimic human diseases. We were thus interested in evaluating the effect of a lentivirus-mediated gene transfer of Rpe65 on cone survival in a new mouse model expressing the mutated Rpe65R91W gene (Samardzija et al. ARVO 2007), a mutation found in LCA patients.
Untreated Rpe65R91W knock-in mice (M. Samardzija et al. ARVO 2007) were sacrificed at P15, P21, 1 month, 2 months, 4 months, 6 months, 8 months and 10 months old. Rpe65R91W knock-in mice treated at P5 or at 1month with an HIV-1-derived lentiviral vector LV-R0.8-RPE65 (Y. Arsenijevic et al. ARVO 2007) were sacrificed at 4 months of age. After enucleation, eyes were fixed in 4% PAF and processed by cryostat sectioning. Immunohistological analyses were performed to evaluate the expression of different markers in the retina.
The cone-specific markers GNAT2, S-opsin and M/L-opsin in Rpe65R91W retinas are already decreased at 1 month old in comparison to wild type controls and continue to decline severely during the following months. However, after Rpe65 gene transfer, in the region of Rpe65 transgene expression, a clear increase in immunolabeling is observed at 4 months old even when the injection of the LV-R0.8-RPE65 occur at 1 month of age.
Rpe65 gene transfer is able to prolong expression of cone-specific genes that are essential for their function. This observation is consistent with a functional rescue of Rpe65R91W mice after lentivirus-mediated gene transfer of Rpe65 in this model. In addition, the therapeutic window in Rpe65R91W knock-in mouse differs from the one we observed in our previous studies in the Rpe65-/- mouse model (Bemelmans et al. PloS Med 2006). Indeed cone markers were detected after Rpe65 gene transfer at 1 month of age in Rpe65R91W mice whereas it was inefficient when applied at 1 month in the Rpe65-/- mouse model. These data suggest that treatment in Rpe65R91W patients may similarly benefit of a large therapeutic window for application of a potential gene therapy.
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