ceRGC and Vision Loss From Traumatic Optic Neuropathy Indud by Repetitive Closed Head Trauma Is Dependent on Timing and Force of Impact.

Purpose: Traumatic optic neuropathy (TON) is often caused by blunt head trauma and has no currently effective treatment. Common animal models of TON induced by surgical crush injury are plagued by variability and do not mimic typical mechanisms of TON injury. Traumatic head impact models have recently shown evidence of TON, but the degree of head impact necessary to consistently induce TON is not well characterized, and it is examined here. Methods: Traumatic skull impacts to C57BL/6J mice were induced using an electromagnetic controlled impact device. One impact performed at two depths (mild and severe), as well as three and five repetitive impacts with an interconcussion interval of 48 hours, were tested. Optokinetic responses (OKRs) and retinal ganglion cell (RGC) loss were measured. Results: Five repetitive mild impacts significantly decreased OKR scores and RGC numbers compared with control mice 10 weeks after initial impact, with maximal pathology observed by 6 weeks and partial but significant loss present by 3 weeks. One severe impact induced similar TON. Three mild impacts also induced early OKR and RGC loss, but one mild impact did not. Equivalent degrees of TON were induced bilaterally, and a significant correlation was observed between OKR scores and RGC numbers. Conclusions: Repetitive, mild closed head trauma in mice induces progressive RGC and vision loss that worsens with increasing impacts. Translational Relevance: Results detail a reproducible model of TON that provides a reliable platform for studying potential treatments over a 3- to 6-week time course

Protocols for Visually Guided Navigation Assessment of Efficacy of Retina-Directed Cell or Gene Therapy in Canines

There has been marked progress in recent years in developing gene delivery approaches for the treatment of inherited blinding diseases. Many of the proof-of-concept studies have utilized rodent models of retinal degeneration. In those models, tests of visual function include a modified water maze swim test, optokinetic nystagmus, and light-dark activity assays. Test paradigms used in rodents can be difficult to replicate in large animals due to their size and awareness of non-visual aspects of the test system. Two types of visual behavior assays have been utilized in canines: an obstacle avoidance course and a forced choice Y maze. Given the progress in developing cell and gene therapies in large animals, such tests will become more and more valuable. This study provides guidelines for carrying out such tests and assesses the challenges and benefits associated with each test

Development of a Retinal Ganglion Cell Specific Gene Therapy Using SIRT1 Signaling for Neuro-Protection (Slides)

Loss of retinal ganglion cells (RGC) can occur by trauma, inflammatory, and ischemia leading to irreversible effects upon vision. Sirtuin 1 (SIRT1) deacetylase has demonstrated therapeutic value in multiple models of optic neuropathy with small molecule biologics. The initial use of gene therapy modestly improved visual outcomes in the EAE-induced mouse model of optic neuritis but with limited effects due to a low transduction rate and lack of cell specificity. Here we investigated the therapeutic potential of RGC specific SIRT1 gene augmentation in a mouse model of optic nerve crush (ONC)

Development of a Retinal Ganglion Cell Specific Gene Therapy Using SIRT1 Signaling for Neuro-Protection (PDF)

Loss of retinal ganglion cells (RGC) can occur by trauma, inflammatory, and ischemia leading to irreversible effects upon vision. Sirtuin 1 (SIRT1) deacetylase has demonstrated therapeutic value in multiple models of optic neuropathy with small molecule biologics. The initial use of gene therapy modestly improved visual outcomes in the EAE-induced mouse model of optic neuritis but with limited effects due to a low transduction rate and lack of cell specificity. Here we investigated the therapeutic potential of RGC specific SIRT1 gene augmentation in a mouse model of optic nerve crush (ONC)

Development of a Retinal Ganglion Cell Specific Gene Therapy Using SIRT1 Signaling for Neuro-Protection (Video)

Loss of retinal ganglion cells (RGC) can occur by trauma, inflammatory, and ischemia leading to irreversible effects upon vision. Sirtuin 1 (SIRT1) deacetylase has demonstrated therapeutic value in multiple models of optic neuropathy with small molecule biologics. The initial use of gene therapy modestly improved visual outcomes in the EAE-induced mouse model of optic neuritis but with limited effects due to a low transduction rate and lack of cell specificity. Here we investigated the therapeutic potential of RGC specific SIRT1 gene augmentation in a mouse model of optic nerve crush (ONC)

Amelioration of Neurosensory Structure and Function in Animal and Cellular Models of a Congenital Blindness.

Most genetically distinct inherited retinal degenerations are primary photoreceptor degenerations. We selected a severe early onset form of Leber congenital amaurosis (LCA), caused by mutations in the gene LCA5, in order to test the efficacy of gene augmentation therapy for a ciliopathy. The LCA5-encoded protein, Lebercilin, is essential for the trafficking of proteins and vesicles to the photoreceptor outer segment. Using the AAV serotype AAV7m8 to deliver a human LCA5 cDNA into an Lca5 null mouse model of LCA5, we show partial rescue of retinal structure and visual function. Specifically, we observed restoration of rod-and-cone-driven electroretinograms in about 25% of injected eyes, restoration of pupillary light responses in the majority of treated eyes, an ∼20-fold decrease in target luminance necessary for visually guided behavior, and improved retinal architecture following gene transfer. Using LCA5 patient-derived iPSC-RPEs, we show that delivery of the LCA5 cDNA restores lebercilin protein and rescues cilia quantity. The results presented in this study support a path forward aiming to develop safety and efficacy trials for gene augmentation therapy in human subjects with LCA5 mutations. They also provide the framework for measuring the effects of intervention in ciliopathies and other severe, early-onset blinding conditions

Safety and durability of effect of contralateral-eye administration of AAV2 gene therapy in patients with childhood-onset blindness caused by RPE65 mutations: a follow-on phase 1 trial

Safety and efficacy have been shown in a phase 1 dose-escalation study involving a unilateral subretinal injection of a recombinant adeno-associated virus (AAV) vector containing the RPE65 gene (AAV2-hRPE65v2) in individuals with inherited retinal dystrophy caused by RPE65 mutations. This finding, along with the bilateral nature of the disease and intended use in treatment, prompted us to determine the safety of administration of AAV2-hRPE65v2 to the contralateral eye in patients enrolled in the phase 1 study