title: Rebuilding lost hearing using cell transplantation.
abstract: OBJECTIVE
  The peripheral auditory nervous system (cochlea and auditory nerve) has a complex anatomy, and it has traditionally been thought that once the sensorineural structures are damaged, restoration of hearing is impossible. In the past decade, however, the potential to restore lost hearing has been intensively investigated using molecular and cell biological techniques, and we can now part with such a pessimistic view. In this review, we examine an important field in hearing restoration research: cell transplantation.
  
  
  METHODS
  Most efforts in this field have been directed to the replacement of hair cells by transplantation to the cochlea. Here, we focus on transplantation to the auditory nerve, from the side of the cerebellopontine angle rather than the cochlea.
  
  
  RESULTS
  Delivery of cells to the cochlea is potentially damaging, and nerve cells transplanted distally to the Schwann-glial transitional zone (cochlear side) may become inhibited when they reach the transitional zone. The auditory nerve is probably the most suitable route for cell transplantation.
  
  
  CONCLUSIONS
  The auditory nerve occupies an important position not only in neurosurgery but also in various diseases in other disciplines, and several lines of recent evidence indicate that it is a key target for hearing restoration. It is familiar to most neurosurgeons, and the recent advances in the molecular and cell biology of inner-ear development are of direct importance to neurorestorative medicine. In this article, we review the anatomy, development, and molecular biology of the auditory nerve and cochlea, with emphasis on the advances in cell transplantation.
authors.affiliation: Department of Otolaryngology, Kyoto University Graduate School of Medicine, Kyoto, Japan. tsekiya@ent.kuhp.kyoto-u.ac.jp
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Sekiya
authors.forename: Ken
authors.initials: K
authors.lastname: Kojima
authors.forename: Masahiro
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Holley
authors.forename: Juichi
authors.initials: J
authors.lastname: Ito
mesh_terms: D000818:Animals; D003056:Cochlear Nerve / Q000601:surgery*; D006319:Hearing Loss, Sensorineural / Q000503:physiopathology / Q000601:surgery*; D006801:Humans; D009416:Nerve Regeneration; D009474:Neurons / Q000502:physiology / Q000637:transplantation*; D019635:Neurosurgical Procedures / Q000379:methods* / Q000639:trends; D023822:Tissue Engineering / Q000379:methods* / Q000639:trends; D016896:Treatment Outcome