(191i) Treatment of Autosomal Dominant Progressive Hearing Loss By in vivo Delivery of Genome Editing Agents

Although genetic factors contribute to almost half of prelingual deafness, treatment options for genetic deafness are limited. We developed a genome editing approach to target a dominantly inherited form of genetic deafness using the clustered, regularly interspaced, short palindromic repeats (CRISPR)-associated protein Cas9 (CRISPR-Cas9). Here we show that cationic lipid-mediated in vivo delivery of Cas9:guide RNA complexes can ameliorate hearing loss in a mouse model of human genetic deafness. We designed and validated in vitro and in cultured cells genome editing agents that preferentially disrupt the dominant deafness-associated allele in the Tmc1 (transmembrane channel-like 1) Beethoven (Bth) mouse model, despite the fact that the mutant Tmc1 (Bth) allele differs from the wild-type allele at only a single base pair. Injection of cationic lipid-encapsulated Cas9:guide RNA complexes that target the Bth allele into the cochlea of neonatal Bth/+ mice substantially reduced progressive hearing loss. We observed higher hair cell survival rates, lower auditory brainstem response (ABR) thresholds, and enhanced acoustic reflex responses for injected ears compared with uninjected contralateral control ears, or compared with ears injected with Cas9:guide RNA complexes that target an unrelated gene. Collectively, these findings suggest protein:RNA complex delivery of genome editing agents in somatic cells in vivo as a potential strategy for the treatment of some autosomal dominant hearing loss diseases.