[Treatment of severe hearing loss. Hopeful results with cochlear implants and nerve cell implantations]

Progress in techniques and strategies for tissue engineering has increased our interest in allografting and xenografting in various organ systems. Previous work has shown that peripherally implanted fetal dorsal root ganglion neurons (DRGs) can grow axons across the boundary between the central and peripheral nervous system in the dorsal root and make functional connections within the spinal cord. We have extended this experimental paradigm to the auditory system and successfully implanted fetal DRG neurons into the normal and deafened cochlea, adjacent to deafferented auditory spiral ganglion neurons. These findings demonstrate the feasibility of using fetal sensory cells in a new strategy to repair or replace the auditory nerve. Further studies will show whether the surviving DRGs can restore a functional conduit from the cochlea to the brainstem. If so, implanting neuronal tissue close to the auditory nerve could be used to regain auditory function in e.g. profoundly deaf patients.