Concise review: the potential of stem cells for auditory neuron generation and replacement.

Sensory hair cells in the mammalian cochlea are sensitive to many insults including loud noise, ototoxic drugs, and ageing. Damage to these hair cells results in deafness and sets in place a number of irreversible changes that eventually result in the progressive degeneration of auditory neurons, the target cells of the cochlear implant. Techniques designed to preserve the density and integrity of auditory neurons in the deafened cochlea are envisaged to provide improved outcomes for cochlear implant recipients. This review examines the potential of embryonic stem cells to generate new neurons for the deafened mammalian cochlea, including the directed differentiation of stem cells toward a sensory neural lineage and the engraftment of exogenous stem cells into the deafened auditory system. Although still in its infancy the aim of this therapy is to restore a critical number of auditory neurons, thereby improving the benefits derived from a cochlear implant.