Morphologic change and hearing recovery after intratympanic application of insulin-like growth factor-1 in Guinea Pig

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 (rhlGF-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 rhlGF-1 treatment significantly reduced the elevation of ABR thresholds after applying the ototoxic agents. Histological analysis revealed that local rhlGF-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. Copyright 2005