Autologous meatal skin graft implantation and intratympanic injection of Pseudomonas aeruginosa: a new experimental mouse model of acquired middle ear cholesteatoma.

ABSTRACT

AIM: To create an experimental model for the biomedical research of middle ear cholesteatoma. METHODS: Cholesteatoma was induced in the right ears of mice. An autologous meatal skin graft was implanted into the middle ear via the tympanic membrane followed by an intratympanic injection of Pseudomonas aeruginosa. Six weeks after surgery, the formation of acquired cholesteatoma was evaluated by macroscopic examination, CT scan, and histological analysis. The expressions of TNF-α, IL-1ß, and IL-6 were measured with real-time PCR. Auditory-evoked brain stem response was used for assessing the changes in hearing levels. RESULTS: None of the mice died during the modeling time. By the sixth postoperative week, cholesteatoma had successfully formed in 23 out of 25 mice, which equals a success rate of 92%. A CT scan revealed that the cholesteatoma was eroding the cochlea. Furthermore, histological analysis demonstrated a cystic structure covered by stratified squamous epithelium and keratin desquamation in the lamellae inside the cystic cavity in the bullae. All mice with experimentally induced cholesteatoma showed hearing impairment and an upregulated expression of TNF-α, IL-1ß, and IL-6. CONCLUSION: The present study successfully developed a mouse model of acquired middle ear cholesteatoma, which provides an extremely valuable tool for auditory and biomedical research. The modeling approach is technically easy and has a high success rate.