Adenoviral-mediated gene transfer into the scala media of the mouse cochlea in vivo

Gene therapy may provide a way to restore inner ear function to deaf and dizzy patients. The mouse is a crucial model system for functional genomics because of the numerous genetic models for hearing loss and inner ear dysfunction. Using an advance generation, E1-/E3-/E2b-(preterminal protein-/polymerase-) Type 5 Adenovirus, we investigated several routes of virus microinjection to determine which were most reproducible in targeting the endolymphatic fluid compartment of the cochlea. We found that when adenovirus is injected via the round window, transduced cells are found only adjacent to the scala tympani and not in the organ of Corti, suggesting that Adenovirus is unable to penetrate the basilar membrane or bony wall of the modiolus. Delivery to the cochlea via the semicircular canals is also inefficient. In contrast, our new method, via a stylomastoid foramen cochleostomy, increases the likelihood of adenovirus gene transfer to the scala media including cells in the organ of Corti and stria vascularis while preserving some hearing. The ability to target delivery of virus and other therapeutic reagents to specific inner ear fluid compartments will facilitate in vivo testing of candidate molecules implicated in multiple aspects of inner ear physiology and regeneration.