Human promoter-driven AAV tools enable precision gene therapy targeting cochlear hair cells

Approximately 50% of hereditary deafness cases and most age-related hearing loss result from cochlear hair cell dysfunction. Adeno-associated virus (AAV)-mediated gene therapy offers a promising strategy for hearing restoration. However, the cochlea's complex cellular composition poses a significant challenge for targeted gene delivery into hair cells. Here, we establish a cross-species screening platform for cochlear AAV tools, applicable from rodents to large animals. Using this platform, we identify human promoters that specifically target inner hair cells, outer hair cells, or all hair cells in mice. The hair cell-specific coProB2 promoter is further validated in Bama miniature pigs and cynomolgus monkeys, achieving specific transgene expression in hair cells without auditory toxicity. Importantly, coProB2-driven gene therapies in DFNB79 and DFNB9 mouse models restore auditory function to near wild-type levels. Thus, this study establishes a cross-species-compatible, hair cell-specific AAV system, providing a versatile toolbox for cochlear hair cell gene therapy.