title: Challenges for stem cells to functionally repair the damaged auditory nerve.
abstract: BACKGROUND
  In the auditory system, a specialized subset of sensory neurons are responsible for correctly relaying precise pitch and temporal cues to the brain. In individuals with severe-to-profound sensorineural hearing impairment these sensory auditory neurons can be directly stimulated by a cochlear implant, which restores sound input to the brainstem after the loss of hair cells. This neural prosthesis therefore depends on a residual population of functional neurons in order to function effectively.
  
  
  METHODS
  In severe cases of sensorineural hearing loss where the numbers of auditory neurons are significantly depleted, the benefits derived from a cochlear implant may be minimal. One way in which to restore function to the auditory nerve is to replace these lost neurons using differentiated stem cells, thus re-establishing the neural circuit required for cochlear implant function. Such a therapy relies on producing an appropriate population of electrophysiologically functional neurons from stem cells, and on these cells integrating and reconnecting in an appropriate manner in the deaf cochlea.
  
  
  CONCLUSIONS
  Here we review progress in the field to date, including some of the key functional features that stem cell-derived neurons would need to possess and how these might be enhanced using electrical stimulation from a cochlear implant.
authors.affiliation: University of Melbourne, Department of Otolaryngology, East Melbourne, Australia. k.needham@unimelb.edu.au
authors.forename: Karina
authors.initials: K
authors.lastname: Needham
authors.forename: Ricki L
authors.initials: RL
authors.lastname: Minter
authors.forename: Robert K
authors.initials: RK
authors.lastname: Shepherd
authors.forename: Bryony A
authors.initials: BA
authors.lastname: Nayagam
mesh_terms: D002454:Cell Differentiation; D003054:Cochlear Implants; D003056:Cochlear Nerve / Q000293:injuries*; D053595:Embryonic Stem Cells / Q000166:cytology; D006801:Humans; D033581:Stem Cell Transplantation