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Haoyu Mao, Marina S. Gorbatyuk, William W. Hauswirth, Alfred S. Lewin; Suppression and Replacement Strategy for Gene Therapy of Autosomal Dominant Retinitis Pigmentosa (ADRP). Invest. Ophthalmol. Vis. Sci. 2011;52(14):5410.
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© ARVO (1962-2015); The Authors (2016-present)
Autosomal dominant retinitis pigmentosa (ADRP) is frequently caused by mutations in the RHO gene, which codes for the opsin of rod photoreceptor cells. The purpose of this study is to treat ADRP with the suppression and replacement strategy by siRNA and normal rhodopsin gene combination in a transgenic mouse model.
We are testing gene therapy in a mouse model of ADRP that expresses a human transgene with a prevalent ADRP mutation: proline 23 substituted by histidine (P23H) in a mouse rhodopsin rho+/- background. We designed and constructed a combination form with resistant rhodopsin (RHO) gene (RHO301) and siRNA301 to maintain a normal level of rhodopsin level and to suppress the expression of the transgene and the endogenous mouse gene. We had previously demonstrated that siRNA301 degrades both mutant human RHO and wild-type mouse mRNA. The resistant RHO gene (RHO301) was generated by introducing silent mutations to eliminate the siRNA cleavage site. The combination virus (RHO301-siRNA301) was delivered in AAV5 into the transgenic mice by subretinal injection in the right eyes, control virus was injected in the left eyes. Full field electroretinography and spectral domain optical coherence tomography were performed at regular intervals to access the function and structure of the retina.
ERG a-wave and b-wave of amplitudes were significantly higher in AAV- RHO301-siRNA301 injected eyes compared to control injected eyes, over a 3-month time course. At 3-months post treatment the ONL thickness of the treated eyes was significantly greater than that of control eyes injected with the control virus. Analysis of rhodopsin protein and RNA levels is in progress.
The finding that single AAV injection of a combination construct containing gene encoding wild-type rhodopsin and siRNA could improve the retinal function in this ADRP model suggests that the suppression and replacement strategy can rescue P23H form of ADRP in mouse model. We would like to develop this approach for use in human patients.
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