Evaluation of the Efficacy of Dexamethasone-Eluting Electrode Array on the Post-Implant Cochlear Fibrotic Reaction by Three-Dimensional Immunofluorescence Analysis in Mongolian Gerbil Cochlea.

Philippine Toulemonde,Michaël Risoud,Juergen Siepmann,Christophe Vincent,Meryem Tardivel,Cyril Beck,Pierre Emmanuel Lemesre,Jean Wattelet

doi:10.3390/jcm10153315

Philippine Toulemonde, Michaël Risoud + Show 6 more

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https://doi.org/10.3390/jcm10153315

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Abstract

Cochlear implant is the method of choice for the rehabilitation of severe to profound sensorineural hearing loss. The study of the tissue response to cochlear implantation and the prevention of post-cochlear-implant damages are areas of interest in hearing protection research. The objective was to assess the efficacy of dexamethasone-eluting electrode array on endo canal fibrosis formation by three-dimensional immunofluorescence analysis in implanted Mongolian gerbil cochlea. Two trials were conducted after surgery using Mongolian gerbil implanted with dexamethasone-eluting or non-eluting intracochlear electrode arrays. The animals were then euthanised 10 weeks after implantation. The cochleae were prepared (electrode array in place) according to a 29-day protocol with immunofluorescent labelling and tissue clearing. The acquisition was carried out using light-sheet microscopy. Imaris software was then used for three-dimensional analysis of the cochleae and quantification of the fibrotic volume. The analysis of 12 cochleae showed a significantly different mean volume of fibrosis (2.16 × 108 μm3 ± 0.15 in the dexamethasone eluting group versus 3.17 × 108 μm3 ± 0.54 in the non-eluting group) (p = 0.004). The cochlear implant used as a corticosteroid delivery system appears to be an encouraging device for the protection of the inner ear against fibrosis induced by implantation. Three-dimensional analysis of the cochlea by light-sheet microscopy was suitable for studying post-implantation tissue damage.

Highlights

Sensorineural hearing loss is characterised by the loss of hair cells and by degeneration of the spiral ganglion neurons [1,2]
Cochlear implantation is used as the surgical solution for the rehabilitation of severe to profound sensorineural hearing loss [3,4]
The inflammatory response that occurs after cochlear implantation promotes the formation of fibrous tissue around the that occurs after cochlear implantation promotes the formation of fibrous tissue around electrode array, which can negatively affect hearing outcomes after implantation [49,50]

Summary

Introduction

Sensorineural hearing loss is characterised by the loss of hair cells and by degeneration of the spiral ganglion neurons [1,2]. Despite its high success rate, cochlear implantation is responsible for cellular destruction, and inflammatory response with the creation of fibrosis and endo-cochlear neo-osteogenesis [5,6,7,8,9,10,11,12]. The extent of this fibrosis correlates with residual hearing loss where it exists [10,13]. In patients with residual hearing, it is important to preserve it to allow rehabilitation by combined electrical and acoustic stimulation cochlear implant devices [17,18]

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