Round window gentamicin application: an inner ear hair cell damage protocol for the mouse

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.