Abstract
Purpose: :
Our aim was to determine whether using AAV-mediated superoxide dismutase1 (SOD1) as an antioxidant gene therapy can rescue oxidative stress-induced retinal degeneration in the rd10 mouse model of retinitis pigmentosa.
Methods: :
Litters of homozygous rd10+/+ were treated in accordance with the recommendations of the Association for Research in Vision and Ophthalmology. A mouse SOD1 cDNA was amplified by PCR and subcloned into a self-complementary recombinant adeno-associated virus (scAAV) vector plasmid containing a chicken β-actin promoter (CBA), and then packaged into AAV5 or AAV8-Y733F capsids according to standard procedures in our lab. Right eyes of rd10 mice were subretinally injected at PN14 while left eyes were uninjected as controls. Scotopic rod and photopic cone ERG signals were recorded and analyzed at 4, 8 and 12 weeks after treatment. After the final ERG recordings, retinal histology was analyzed by quantifying the number of nuclei in the outer nuclear layer and quantifying photoreceptor apoptotic cell death by TUNEL analysis.
Results: :
Four weeks after treatment with either vector, ERG analysis of rd10 mice showed that 30~50% of normal scotopic rod and photopic cone ERG amplitudes were preserved in treated eyes compared to the wild-type mice, and that treated eyes had three to five-fold higher ERG amplitudes than partner untreated eyes. Histological analysis showed 3-5 layers of photoreceptors nuclei in the outer nuclear layer of treated eyes compared to 1-3 layers in partner control eyes at 12 weeks post-treatment. TUNEL assays revealed a significant decrease in apoptotic photoreceptors in treated versus control rd10 eyes.
Conclusions: :
AAV-mediated SOD1 over-expression in photoreceptors was demonstrated to preserve photoreceptor function and structure in the rd10 mouse model of retinitis pigmentosa due to a recessive Pde6b mutation. As SOD1 is one of the major enzymes for the intracellular anti-oxidant response, it should be considered as a therapeutic option for oxidative stress-induced neurodegenerative diseases.
Keywords: gene transfer/gene therapy • antioxidants • oxidation/oxidative or free radical damage