title: Development of an electrode for the artificial cochlear sensory epithelium.
abstract: An artificial cochlear sensory epithelium has been developed on the basis of a new concept that the piezoelectric membrane, which converts mechanical distortion into electricity, can mimic the function of the inner hair cell and basilar membrane of the mammalian cochlea. Our previous research demonstrated that the piezoelectric membrane generated electrical outputs in response to the sound stimulation after implantation into the guinea pig cochlea, whereas electrodes for the stimulation of spiral ganglion neurons have not been fabricated, and a method to fix the device in the cochlea is also required to show proof-of-concept. In the present study, to achieve proof-of-concept of hearing recovery by implantation of the artificial cochlear sensory epithelium, we fabricated new electrodes that stick into the cochlear modiolus, which also play a role in the fixation of the device in the cochlea. The efficacy of new electrodes for fixation of the device in the cochlea and for the stimulation of spiral ganglion neurons was estimated in guinea pigs. Four weeks after implantation, we confirmed that the devices were in place. Histological analysis of the implanted cochleae revealed inconspicuous fibrosis and scar formation compared with the sham-operated specimens (n = 5 for each). The terminal deoxynucleotidyl transferase dUTP nick end labeling method was used to assess cell death due to surgical procedures in the cochleae that were harvested after 1 day (n = 6) and 7 days (n = 6) of implantation; there was no significant increase in apoptotic cell death in the implanted cochleae compared with sham-operated cochleae. In seven animals, serial measurements of electrically evoked auditory brainstem responses were obtained, with the electrode positioned in the scala tympani and with the electrode inserted into the cochlear modiolus. With the insertion of electrodes into the cochlear modiolus, significant reduction was achieved in the thresholds of electrically evoked auditory brainstem responses compared with those placed in the scala tympani (p = 0.028). These findings indicated that the new electrodes efficiently fixed the device in the cochlea and were able to stimulate spiral ganglion neurons.
authors: Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: y_tona@ent.kuhp.kyoto-u.ac.jp.
authors: Yosuke
authors: Y
authors: Tona
authors: Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan; Inaoka ENT Clinic, 2-1-14-201, Neyaminami, Neyagawa 572-0855, Japan. Electronic address: t_inaoka@ent.kuhp.kyoto-u.ac.jp.
authors: Takatoshi
authors: T
authors: Inaoka
authors: Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: ito@ent.kuhp.kyoto-u.ac.jp.
authors: Juichi
authors: J
authors: Ito
authors: Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan. Electronic address: kawano@me.es.osaka-u.ac.jp.
authors: Satoyuki
authors: S
authors: Kawano
authors: Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kawaharacho 54, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan. Electronic address: tnakagawa@ent.kuhp.kyoto-u.ac.jp.
authors: Takayuki
authors: T
authors: Nakagawa
mesh_terms: D000818:Animals; D017209:Apoptosis; D001489:Basilar Membrane / Q000502:physiology; D003051:Cochlea / Q000502:physiology*; D019929:Cochlear Implantation; D003054:Cochlear Implants; D004558:Electric Stimulation; D004566:Electrodes; D004848:Epithelium / Q000378:metabolism*; D004867:Equipment Design; D016057:Evoked Potentials, Auditory, Brain Stem / Q000502:physiology; D005355:Fibrosis / Q000473:pathology; D006168:Guinea Pigs; D006199:Hair Cells, Auditory, Inner / Q000502:physiology; D006319:Hearing Loss, Sensorineural / Q000628:therapy; D007150:Immunohistochemistry; D007249:Inflammation; D009339:Needles; D009474:Neurons / Q000378:metabolism; D012533:Scala Tympani / Q000473:pathology; D013136:Spiral Ganglion / Q000502:physiology*; D014544:Uridine Triphosphate / Q000737:chemistry
chemical_list: D014544:Uridine Triphosphate
keywords: Mechanoelectrical stimulation; Modiolus stimulation; Piezoelectric membrane