Cochlear protection by local insulin-like growth factor-1 application using biodegradable hydrogel.
OBJECTIVE
The aim of this experimental study was to examine the potential of local recombinant human insulin-like growth factor-1 (rhIGF-1) application through a biodegradable hydrogel for the treatment of cochleae.


METHODS
A hydrogel immersed with rhIGF-1 was placed on the round window membrane of Sprague-Dawley rats while a hydrogel immersed with physiological saline was applied to control animals. On day 3 after drug application, the animals were exposed to white noise at 120 dB sound pressure level (SPL) for 2 hours. Cochlear function was monitored using measurements of auditory brain stem responses (ABRs) at frequencies of 8, 16, and 32 kHz. The temporal bones were collected 7 or 30 days after noise exposure and the loss of hair cells was quantitatively analyzed.


RESULTS
Local rhIGF-1 treatment significantly reduced the elevation of ABR thresholds on days 7 and 30 after noise exposure. Histologic analysis revealed that local rhIGF-1 treatment significantly prohibited the loss of outer hair cells.


CONCLUSIONS
These findings demonstrate that local IGF-1 application through the biodegradable hydrogel has the potential for protection of cochleae from noise trauma.
Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Koji
K
Iwai
Takayuki
T
Nakagawa
Tsuyoshi
T
Endo
Yoshinori
Y
Matsuoka
Tomoko
T
Kita
Tae-Soo
TS
Kim
Yasuhiko
Y
Tabata
Juichi
J
Ito
D000287:Administration, Topical; D000818:Animals; D047070:Bandages, Hydrocolloid; D001673:Biodegradation, Environmental; D015834:Cochlear Diseases / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D004195:Disease Models, Animal; D016503:Drug Delivery Systems; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006317:Hearing Loss, Noise-Induced / Q000150:complications / Q000503:physiopathology / Q000517:prevention & control; D007334:Insulin-Like Growth Factor I / Q000008:administration & dosage* / Q000627:therapeutic use; D051381:Rats; D017207:Rats, Sprague-Dawley; D016896:Treatment Outcome
D007334:Insulin-Like Growth Factor I