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Stem Cells International
Volume 2016 (2016), Article ID 1781202, 10 pages
http://dx.doi.org/10.1155/2016/1781202
Research Article

Innervation of Cochlear Hair Cells by Human Induced Pluripotent Stem Cell-Derived Neurons In Vitro

1Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, USA
2Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA
3Centre for Eye Research Australia, University of Melbourne, East Melbourne, VIC 3002, Australia
4Centre for Neural Engineering, University of Melbourne, Parkville, VIC 3010, Australia
5Department of Audiology and Speech Pathology, University of Melbourne, Parkville, VIC 3010, Australia
6Bionics Institute, University of Melbourne, East Melbourne, VIC 3002, Australia

Received 1 October 2015; Accepted 31 December 2015

Academic Editor: Tara Walker

Copyright © 2016 Niliksha Gunewardene et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Induced pluripotent stem cells (iPSCs) may serve as an autologous source of replacement neurons in the injured cochlea, if they can be successfully differentiated and reconnected with residual elements in the damaged auditory system. Here, we explored the potential of hiPSC-derived neurons to innervate early postnatal hair cells, using established in vitro assays. We compared two hiPSC lines against a well-characterized hESC line. After ten days’ coculture in vitro, hiPSC-derived neural processes contacted inner and outer hair cells in whole cochlear explant cultures. Neural processes from hiPSC-derived neurons also made contact with hair cells in denervated sensory epithelia explants and expressed synapsin at these points of contact. Interestingly, hiPSC-derived neurons cocultured with hair cells at an early stage of differentiation formed synapses with a higher number of hair cells, compared to hiPSC-derived neurons cocultured at a later stage of differentiation. Notable differences in the innervation potentials of the hiPSC-derived neurons were also observed and variations existed between the hiPSC lines in their innervation efficiencies. Collectively, these data illustrate the promise of hiPSCs for auditory neuron replacement and highlight the need to develop methods to mitigate variabilities observed amongst hiPSC lines, in order to achieve reliable clinical improvements for patients.