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

Abstract

Clinical genome editing is emerging for rare disease treatment, but one of the major limitations is the targeted delivery of CRISPR editors. 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 KCNJ13W53X/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. Functional Kir7.1 channels were recorded from the edited LCA16-iPSC-RPE. In the LCA16 mouse model (Kcnj13W53X/+{Delta}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, reinforces the effectiveness of nonviral genome editing therapy for rare inherited disorders. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=174 SRC="FIGDIR/small/499808v3_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@1fb405eorg.highwire.dtl.DTLVardef@3f14c1org.highwire.dtl.DTLVardef@16bb82aorg.highwire.dtl.DTLVardef@107d862_HPS_FORMAT_FIGEXP M_FIG C_FIG