Abstract
PurposeTo investigate whether antioxidant gene therapy protects the structure and function of retina in a murine model of RPE atrophy, and to determine whether antioxidant gene therapy can prevent degeneration once it has begun.MethodsWe induced mitochondrial oxidative stress in RPE by conditional deletion of Sod2, the gene for manganese superoxide dismutase (MnSOD). These mice exhibited localized atrophy of the RPE and overlying photoreceptors. We restored Sod2 to the RPE of one eye using adeno-associated virus (AAV) by subretinal injection at an early (6 weeks) and a late stage (6 months), injecting the other eye with an AAV vector expressing green fluorescent protein (GFP). Retinal degeneration was monitored over a period of 9 months by electroretinography (ERG) and spectral-domain optical coherence tomography (SD-OCT). Immunohistochemical and histologic analyses were conducted to measure oxidative stress markers and to visualize retinal structure.ResultsOne month after delivery, the AAV-Sod2 injection resulted in production of MnSod in the RPE and negligible expression in the neural retina. Electroretinography and OCT suggested no adverse effects due to increased expression of MnSOD or subretinal injection. Decrease in the ERG response and thinning retinal thickness was significantly delayed in eyes with early treatment with the Sod2 vector, but treatment at 6 months of age did not affect the ERG decline seen in these mice.ConclusionsWe conclude that antioxidant gene therapy may be effective in preventing the detrimental effects of oxidative stress, but may not be beneficial once substantial tissue damage has occurred.
Highlights
To investigate whether antioxidant gene therapy protects the structure and function of retina in a murine model of retinal pigment epithelial (RPE) atrophy, and to determine whether antioxidant gene therapy can prevent degeneration once it has begun
Even though treatments are available for wet Age-related macular degeneration (AMD), there is no effective treatment for geographic atrophy (GA), though research on replacement of the RPE is in progress.[2,3]
We found that early replacement of Sod[2] in RPE delayed retinal degeneration, whereas replacement of Sod[2] after substantial RPE damage had already occurred did not prove effective, suggesting that antioxidant gene therapy may be useful as a preventive but not as a therapy for GA
Summary
We induced mitochondrial oxidative stress in RPE by conditional deletion of Sod[2], the gene for manganese superoxide dismutase (MnSOD). These mice exhibited localized atrophy of the RPE and overlying photoreceptors. The mice used for the experiment were transgenic for PVMD2-rtTA and tetOPhCMVcre and were homozygous for Sod[2] containing loxP sites surrounding exon 3.10,21 This model and the procedure for induction of cre recombinase has been described by Mao et al.[10] For procedures such as subretinal injection, electoretinography (ERG), fundus imaging, and spectral-domain optical coherence tomography (SD-OCT), mice were anesthetized by intraperitoneal injection of ketamine (95 mg/kg) and xylazine (8 mg/kg). Fort Worth, TX, USA) injection was used to euthanize the mice
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
