Yonsei Advanced Science Institute

Outer hair cell (OHC) degeneration is a major cause of progressive hearing loss and presbycusis. Despite the high prevalence of these disorders, targeted therapy is currently not available.
Methods: We generated a mouse model harboring Kcnq4W276S/+ to recapitulate DFNA2, a common genetic form of progressive hearing loss accompanied by OHC degeneration. After comprehensive
optimization of guide RNAs, Cas9s, vehicles, and delivery routes, we applied in vivo gene editing strategy to disrupt the dominant-negative allele in Kcnq4 and prevent progressive hearing loss.
Results: In vivo gene editing using a dual adeno-associated virus package targeting OHCs significantly improved auditory thresholds in auditory brainstem response and distortion-product otoacoustic
emission. In addition, we developed a new live-cell imaging technique using thallium ions to investigate the membrane potential of OHCs and successfully demonstrated that mutant allele disruption resulted in more hyperpolarized OHCs.