Cell of the month: An outer hair cell of the inner ear

Abstract Inner ear trauma caused by cochlear implantation is a severe clinical problem. It was shown that an electrode alginate coating can reduce the insertion forces in vitro. The grade of the alginate viscosity can be adjusted by using different metal ions for cross-linking the salts of the alginic acid. The aim was to investigate the stability and inner ear biocompatibility of alginate using different in vitro established cross-linkers. Alginate beads were cross-linked in either calcium chloride (CaCl2) or barium chloride (BaCl2) solution. The beads were cultivated in artificial perilymph and stability and swelling were observed for 13 months. Ototoxicity was tested on cochlear whole mount explants from neonatal rats. Neomycin served as positive control to induce hair cell damage and explants without any addition served as negative control. The beads and explants were co-cultured for 48 hours and the hair cell survival was analysed microscopically. Neomycin treatment induced an extensive inner and outer hair cell loss. Neither CaCl2 nor BaCl2 cross-linked alginate beads caused any damage to the hair cells. Even though the same volume of alginate and cross-linkers were used, in CaCl2 cross-linked beads were initially almost double the size of in BaCl2 cross-linked beads. None of the cross-linked alginate beads had a significant volume change within 3 months being cultured in artificial perilymph. After 3 months the CaCl2 cross-linked beads swelled massively and dissolved within one week whereas BaCl2 cross-linked alginate beads remained unchanged until month 13 after culture start. Alginate beads gelled with both cross-linkers are biocompatible with the inner ear sensory epithelium. Both cross-linkers ensure a stable gelation of alginate but a swelling followed by degradation of the in CaCl2 cross-linked beads occurred after 3 months. For coatings, which need to be long term stable, BaCl2 should be chosen whereas CaCl2 may be more suitable for applications where limited stability is needed and the swelling is not affecting the surrounding tissue. Therefore, BaCl2 cross-linking of alginate may be the best choice for cochlear implant coating.

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OHC-TRECK: A Novel System Using a Mouse Model for Investigation of the Molecular Mechanisms Associated with Outer Hair Cell Death in the Inner Ear

Scientific Reports ◽

10.1038/s41598-019-41711-2 ◽

2019 ◽

Vol 9 (1) ◽

Author(s):

Kunie Matsuoka ◽

Kenta Wada ◽

Yuki Miyasaka ◽

Shumpei P. Yasuda ◽

Yuta Seki ◽

...

Keyword(s):

Cell Death ◽

Mouse Model ◽

Hair Cell ◽

Inner Ear ◽

Molecular Mechanisms ◽

Outer Hair Cell ◽

Hair Cell Death

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A Neuro-Fuzzy Model for Simulating Outer Hair Cell of Human Cochlea

Advances in Bioengineering ◽

10.1115/imece2005-80644 ◽

2005 ◽

Author(s):

Balaje T. Thumati ◽

D. Subbaram Naidu ◽

Larry Stout

Keyword(s):

Neural Network ◽

Fuzzy Logic ◽

Hair Cell ◽

Inner Ear ◽

Auditory System ◽

Outer Hair Cell ◽

Basilar Membrane ◽

Fuzzy Model ◽

Feed Forward Neural Network ◽

Human Auditory System

Understanding the functioning of the human auditory system has been of interest for decades and many mathematical models have been developed based on experimental results. Many of these models address the key components of the human auditory system: outer ear, middle ear, and inner ear, which consists of cochlea and organ of corti. In this paper, a novel approach for human auditory model is developed that is based on the concepts of fuzzy logic for simulating basilar membrane and stereocilia, and a feed-forward neural network for simulating outer hair cell of the inner ear. Frequency, intensity and the direction of stereocilia movement are the three inputs to the fuzzy logic portion of the model. The output of this block is the net force, which becomes the input to the neural network. The implementation and simulated results using MATLAB® are presented.

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