Int. Adv. Otol. 2009; 6(1); 46-52

Morphologic change and hearing recovery after intratympanic application of insulin-like growth factor-1 in guinea pig
Jung-Hae Cho, Kyoung-Ho Park, Shi-Nae Park, Sang-Won Yeo.  
Department of Otolaryngology Head and Neck Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea  jhchomd@catholic.ac.kr

Objective: This study investigated effectiveness of intratympanic insulin-like growth factor-1 (IGF-1) application on deaf guinea
pigs.

Materials and Methods: The coadministration of kanamycin and ethacrynic acid was used to deafen the guinea pigs. An
absorbable gelatin sponge immersed in recombinant human insulin-like growth factor-1 (rhIGF-1) was placed on the round
window membrane of the experimental ear while a sponge containing saline was applied to control ear. Hearing function was
assessed by auditory brain stem responses (ABRs). The temporal bones were collected for analyzing histology of hair cells in
the organ of Corti.

Results: Local rhIGF-1 treatment significantly reduced the elevation of ABR thresholds after applying the ototoxic agents.
Histological analysis revealed that local rhIGF-1 treatment could promote repair of the hair cells.

Conclusion: These findings demonstrate that local IGF-1 application has potential in repairing outer hair cells damaged by
ototoxic agents. On the basis of this study, the clinical use of local IGF-1 application with a gelatin sponge may be useful as a
therapeutic option for the treatment of sensorineural hearing loss.