Retinal preservation following lateral ventricle injection of AAV9-Cln6 into mouse model for Batten disease

Abstract

Purpose : Batten disease (neuronal ceroid lipofusinosis-NCLs) are a group of neurodegenerative lysosomal storage disease mainly affecting children. Loss of vision is also a major symptom in CNLs. There is no treatment yet. Mutation in Cln6 causes variant late-infantile NCL with vision impairment. Here, we investigate photoreceptor preservation following AAV8-Cln6 intra-ventricle delivery.

Methods : Wild type and homozygous Cln6-mutant mice (Cln6^nclf) on C57BL/6J backgrounds were used for all studies and were housed under identical conditions. Mice received a single intracerebroventricular (ICV) injection of either PBS (n=18) or scAAV9.CB.CLN6 (n=18) (5x10¹⁰ vg/animal in 4 μL volume) at postnatal day one (the day after birth) following hypothermia sedation. Animals were monitored continuously until fully recovered from sedation and daily thereafter. Subretinal injection: AAV9-Cln6 was injected at 3 (n=11) and 6 months (n=10), AAV-GFP (n=10) or PBS (n=10) injection was used as control. Eyeballs were collected at 3-, 6- and 9-month time points. Retinal cryostat sections were processed for histology and immunofluorescence.

Results : ICV delivery of scAAV9.CB.CLN6 at P1 significantly rescue photoreceptors (8-10 layers) at both 6-and 9-month time points, compared with 0-3 layers in PBS treated eyes. The preservation of photoreceptors at the central part of the eye is more evidence than peripheral part. It is noted that degeneration rate was uneven in these mice with nasal and dorsal part of the retina degenerating slower than the temporal and ventral part of the retina. The Subretinal injection of scAAV9.CB.CLN6 did not rescue photoreceptors, similar to AAV-GFP and PBS treated retinas. In addition, T cell infiltration was frequently observed in mice received injection at 6 months of age. There is advanced retinal degeneration with age, secondary pathology including inner retinal neuron migration, loss of retinal neurons were observed in 9 month old mice.

Conclusions : ICV delivery of scAAV9.CB.CLN6 at P1 can significantly prevent photoreceptors from degeneration, especially the central part of the retina. The peripheral part of retina still underwent progressive degeneration, which needs to be further studied. In addition, translational delivery of Cln6 at adult mice to examine photoreceptor preservation and correlate with functional evaluation is under investigation.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.