# Exploring the Proteomic Landscape of Cochlear Implant Trauma: An iTRAQ-Based Quantitative Analysis Utilizing an Ex Vivo Model

## TL;DR

This study identifies proteins and pathways involved in cochlear damage during implantation, aiming to preserve residual hearing.

## Contribution

Novel identification of trauma-induced proteomic changes in cochlear implantation using an ex vivo model and iTRAQ technology.

## Key findings

- Distinct molecular pathways are activated in cochlear damage following electrode insertion trauma.
- Confocal microscopy confirmed the expression of identified proteins in traumatized cochlear explants.
- A topographic array of molecular pathways was observed from the base to apex of the cochlea post-trauma.

## Abstract

Background: Cochlear implantation is widely used to provide auditory rehabilitation to individuals with severe-to-profound sensorineural hearing loss. However, electrode insertion during cochlear implantation leads to inner ear trauma, damage to sensory structures, and consequently, loss of residual hearing. There is very limited information regarding the target proteins involved in electrode insertion trauma (EIT) following cochlear implantation. Methods: The aim of our study was to identify target proteins and host molecular pathways involved in cochlear damage following EIT utilizing the iTRAQ™ (isobaric tags for relative and absolute quantification) technique using our ex vivo model. The organ of Corti (OC) explants were dissected from postnatal day 3 rats and subjected to EIT or left untreated (control). The proteins were extracted, labelled, and subjected to ultra-high performance liquid chromatography–tandem mass spectrometry. Results: We identified distinct molecular pathways involved in EIT-induced cochlear damage. Confocal microscopy confirmed the expression of these identified proteins in OC explants subjected to EIT. By separating the apical, middle, and basal cochlear turns, we deciphered a topographic array of host molecular pathways that extend from the base to the apex of the cochlea, which are activated post-trauma following cochlear implantation. Conclusions: The identification of target proteins involved in cochlear damage will provide novel therapeutic targets for the development of effective treatment modalities for the preservation of residual hearing in implanted individuals.