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Updated: Aug 24, 2026
The Mouse Round-window Approach for Ototoxic Agent Delivery: A Rapid and Reliable Technique for Inducing Cochlear Cell Degeneration
Published on: November 26, 2015
Round window gentamicin application: an inner ear hair cell damage protocol for the mouse
Jennifer L Heydt1, Lisa L Cunningham, Edwin W Rubel
1Department of Otolaryngology-Head and Neck Surgery, University of Washington, Box 356515, Seattle, WA 98195-7923, USA.
Abstract:
It is important to develop an inner ear damage protocol for mice that avoids systemic toxicity and produces damage in a relatively rapid fashion, allowing for study of early cellular and molecular mechanisms responsible for hair cell death and those that underlie the lack of hair cell regeneration in mammals. Ideally, this damage protocol would reliably produce both partial and complete lesions of the sensory epithelium. We present a method for in vivo induction of hair cell damage in the mouse via placement of gentamicin-soaked Gelfoam in the round window niche of the inner ear, an adaptation of a method developed to study hair cell regeneration in chicks. A total of 82 subjects underwent the procedure. Variable doses of gentamicin were used (25, 50, 100 and 200 microg). Saline-soaked Gelfoam, sham-operations and the contralateral, non-operated cochlea were used as controls. Survival periods were 1, 3 and 14 days. Damage was assessed on scanning electron microscopy. We found that this method produces relatively rapid hair cell damage that varies with dose and can extend the entire length of the sensory epithelium. In addition, this protocol produces no systemic toxicity and preserves the contralateral ear as a control.
Insights
A new gentamicin-based method rapidly induces inner ear hair cell damage in mice without systemic toxicity. This protocol allows for studying hair cell death and the lack of mammalian regeneration.
Area of Science:
- Ototoxicity and Regenerative Medicine
- Auditory Neuroscience
- Mammalian Inner Ear Physiology
Background:
- Developing reliable methods to induce inner ear damage is crucial for studying hair cell death and regeneration.
- Existing methods may cause systemic toxicity or lack control over lesion extent.
- Mammalian hair cells do not regenerate, making in vivo models essential for research.
Purpose of the Study:
- To establish a rapid, in vivo inner ear hair cell damage protocol in mice.
- To achieve dose-dependent and variable lesions of the sensory epithelium.
- To avoid systemic toxicity and maintain a contralateral control.
Main Methods:
- Gentamicin-soaked Gelfoam was placed in the round window niche of mouse inner ears.
- Doses of 25, 50, 100, and 200 microg of gentamicin were tested.
- Control groups included saline-soaked Gelfoam, sham operations, and contralateral ears.
- Damage was assessed via scanning electron microscopy at 1, 3, and 14 days post-procedure.
Main Results:
- The method successfully induced rapid hair cell damage in the inner ear.
- Damage extent varied with gentamicin dose and could affect the entire sensory epithelium.
- No systemic toxicity was observed.
- The contralateral, non-operated ear remained preserved as a control.
Conclusions:
- This gentamicin-induced inner ear damage protocol is effective for mouse models.
- It provides a rapid, controllable, and non-systemically toxic method for hair cell research.
- The protocol supports the study of early mechanisms of hair cell death and mammalian regeneration failure.
