Journal Article

AAV2/4-RS1 gene therapy in the retinoschisin knockout mouse model of X-linked retinoschisis

Scruggs, Brittni A., Salesevic, Adisa, Helms, Megan, Baker, Sheila A., Cherascu, Ioana, Drack, Arlene V., Bhattarai, Sajag, Stalter, Elliot, Laird, Joseph

2022

Overview

To evaluate efficacy of a novel adeno-associated virus (AAV) vector, AAV2/4-RS1, for retinal rescue in the retinoschisin knockout (Rs1-KO) mouse model of X-linked retinoschisis (XLRS). Brinzolamide (Azopt®), a carbonic anhydrase inhibitor, was tested for its ability to potentiate the effects of AAV2/4-RS1. AAV2/4-RS1 with a cytomegalovirus (CMV) promoter (2x1012 viral genomes/mL) was delivered to Rs1-KO mice via intravitreal (N = 5; 1μL) or subretinal (N = 21; 2μL) injections at postnatal day 60-90. Eleven mice treated with subretinal therapy also received topical Azopt® twice a day. Serial full field electroretinography (ERG) was performed starting at day 50-60 post-injection. Mice were evaluated using a visually guided swim assay (VGSA) in light and dark conditions. The experimental groups were compared to untreated Rs1-KO (N = 11), wild-type (N = 12), and Rs1-KO mice receiving only Azopt® (N = 5). Immunofluorescence staining was performed to assess RS1 protein expression following treatment. The ERG b/a ratio was significantly higher in the subretinal plus Azopt® (p<0.0001), subretinal without Azopt® (p = 0.0002), and intravitreal (p = 0.01) treated eyes compared to untreated eyes. There was a highly significant subretinal treatment effect on ERG amplitudes collectively at 7-9 months post-injection (p = 0.0003). Cones showed more effect than rods. The subretinal group showed improved time to platform in the dark VGSA compared to untreated mice (p<0.0001). RS1 protein expression was detected in the outer retina in subretinal treated mice and in the inner retina in intravitreal treated mice. AAV2/4-RS1 shows promise for improving retinal phenotype in the Rs1-KO mouse model. Subretinal delivery was superior to intravitreal. Topical brinzolamide did not improve efficacy. AAV2/4-RS1 may be considered as a potential treatment for XLRS patients.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Animals / Biology and Life Sciences / Body temperature / Carbonic anhydrase / Carbonic anhydrases / Complications and side effects / Cornea / Cytomegalovirus / Effectiveness / Electroretinograms / Electroretinography / Evaluation / Gene therapy / Genetic Therapy / Genomes / Immunofluorescence / Injection / Laboratories / Medicine and Health Sciences / Mice / Mice, Knockout / Patient outcomes / Phenotypes / Photoreceptors / Proteins / Research and Analysis Methods / Retina / Retinoschisis / Retinoschisis - genetics / Retinoschisis - therapy / Social Sciences / Tomography / Viruses