Nonviral base editing of KCNJ13 mutation preserves vision in a model of inherited retinal channelopathy

Clinical genome editing is emerging for rare disease treatment, but one of the major limitations is the targeting of CRISPR editors delivery. We delivered base editors to the retinal pigmented epithelium (RPE) in the mouse eye using silica nanocapsules (SNC) as a treatment for retinal degeneration. Leber Congenital Amaurosis (LCA16) is a rare pediatric blindness caused by point mutations in the KCNJ13 gene, a loss-of-function inwardly rectifying potassium channel (Kir7.1) in the RPE. SNC carrying adenine base editor (ABE8e) mRNA and single-guide RNA precisely and efficiently corrected KCNJ^13W53X/W53X mutation. Editing in both patient fibroblasts (47%) and human-induced pluripotent stem cell-derived RPE (LCA16-iPSC-RPE) (17%) had a negligible off-target response. We detected functional Kir7.1 channels in the edited LCA16-iPSC-RPE. In the LCA16 mouse model (Kcnj13^W53X/+∆R), RPE cells targeted SNC delivery of ABE8e mRNA preserved normal visual function measured by full-field electroretinogram (ERG). Moreover, multifocal ERG confirmed the topographic measure of electrical activity primarily originating from the edited retinal area at the injection site. Preserved retina structure, post-treatment, was established by Optical Coherence Tomography (OCT). This preclinical validation of targeted ion channel functional rescue, a challenge for pharmacological and genomic interventions, reinforced the effectiveness of nonviral genome editing therapy for rare inherited disorders.