Cell-specific delivery of GJB2 restores auditory function in mouse models of DFNB1 deafness and mediates appropriate expression in NHP cochlea.

Mutations in the gene cause the most common form of human hereditary hearing loss, known as DFNB1. is expressed in two cell groups of the cochlea-epithelial cells of the organ of Corti and fibrocytes of the inner sulcus and lateral wall-but not by sensory hair cells or neurons. Attempts to treat mouse models of DFNB1 with AAV vectors mediating nonspecific expression have not substantially restored function, perhaps because inappropriate expression in hair cells and neurons could compromise their electrical activity. Here, we used genomic chromatin accessibility profiling to identify candidate gene regulatory elements (GREs) that could drive cell-type-specific expression of in the cochlea. HA-tagged GJB2, delivered to a conditional knockout model in an AAV vector with GRE control of expression, was localized to the appropriate cell types, prevented the cochlear degeneration observed in untreated knockout mice, and partially rescued hearing sensitivity. In a partial knockdown mouse model, such exogenous GJB2 prevented degeneration and completely restored hearing sensitivity. We tested control of expression by these GREs in nonhuman primate cochleas and found that vector-delivered human GJB2.HA was located in the appropriate cell types and caused little or no reduction in hearing sensitivity. Together, these findings suggest that GRE-mediated expression of could prevent hearing loss in DFNB1 patients.