Mobility task shows rescue of scotopic vision in a swine model for autosomal dominant Retinitis Pigmentosa after treatment with the meganuclease Rho 1-2

Abstract

Purpose : Retinitis pigmentosa (RP) is the most common form of inherited retinal disease with ~1:5000 people affected worldwide. The substitution of Proline to Histidine (P23H) at position 23 in the rhodopsin protein is the most common form of adRP in North America. We have shown that treating a transgenic P23H human RHO pig model of adRP (TgP23H hRHO) with a gene-editing meganuclease Rho 1-2, recovers rod structure and restores rod function. We ran WT, Rho1-2 treated and untreated TgP23H hRHO (Tg) pigs through an obstacle course to quantify visually guided mobility under light- and dark-adapted conditions using motion analysis software.

Methods : Rho 1-2 packaged in AAV5 with a GRK1 promoter was subretinally injected into one or both eyes of neonatal Tg pigs. After ~10 months, we tested visually guided behavior by running pigs through an obstacle course. Pigs were trained binocularly under light-adapted conditions. Pigs were food deprived (16hrs) and tested monocularly under light (150 lux) or dark (10 lux) conditions (30 mins dark adaptation). At the end of each run, pigs received a food reward. Barrier location was randomized between trials. Videos were recorded with an infrared handheld camera that moved along with the pig (outside of the course). From the videos, positions of the pig’s front feet relative to obstacles were estimated using Kinovea motion analysis software. Data were plotted using SmartDraw charting software. Foot positions were imported into R and evaluated using its trajr package functions.

Results : Under conditions that require rod function, Rho 1-2 treated Tg eyes led to significantly fewer collisions (~33%), shorter path length (~40%) and overall duration (~67%) in the run compared to untreated Tg eyes. The Tg pig’s path through the obstacle course using the treated eye was less tortuous, compared to untreated Tg. In 1 Tg pig only one eye was treated and the visually guided behavior using its treated eye was better compared to its untreated eye.

Conclusions : We developed an analytical tool that uses raw videos to quantitatively analyze foot position in large animals that quantifies maze mobility. Mobility mediated by Rho 1-2 treatment in TgP23H hRHO eyes was significantly improved under rod mediated conditions. These results extend Rho 1-2 mediated improvements shown in retinal rod function and structure in TgP23H hRHO pigs.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.