Novel strategy for treatment of inner ears using a biodegradable gel.
OBJECTIVE
The present study aimed to evaluate the efficacy of a biodegradable hydrogel as a drug-delivery medium for the inner ear. Brain-derived neurotrophic factor (BDNF) was chosen as the agent to be administered.


METHODS
First, we used an enzyme-linked immunosorbent assay to measure BDNF concentrations in the cochlear fluid after placing a hydrogel containing this agent onto the round-window membrane of the ear. Second, the functional and histologic protection of the auditory primary neurons (spiral ganglion neurons [SGNs]) by BDNF applied through the hydrogel was examined using an animal model of SGN degeneration.


RESULTS
The results revealed sustained delivery of BDNF into the cochlear fluid by way of the hydrogel. Second, the functional and histologic protection of the auditory primary neurons (SGNs) by BDNF applied through the hydrogel was examined using an animal model of SGN degeneration. The measurement of electrically evoked auditory-brainstem responses demonstrated that BDNF delivered by way of the hydrogel significantly reduced the threshold elevation. Immunohistochemistry for neurofilament 200 kD demonstrated increased survival of SGNs because of BDNF application through the hydrogel.


CONCLUSIONS
These findings indicate that biodegradable hydrogels can be used for drug delivery to the inner ear.
Endo
Tsuyoshi
T
Department of Otolaryngology-Head and Neck Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Nakagawa
Takayuki
T
Kita
Tomoko
T
Iguchi
Fukuichiro
F
Kim
Tae-Soo
TS
Tamura
Tetsuya
T
Iwai
Koji
K
Tabata
Yasuhiko
Y
Ito
Juichi
J
D000818:Animals; D001673:Biodegradation, Environmental; D019208:Brain-Derived Neurotrophic Factor / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004337:Drug Carriers; D007758:Ear, Inner / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D006168:Guinea Pigs; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D007150:Immunohistochemistry; D010498:Perilymph / Q000378:metabolism*; D013136:Spiral Ganglion / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
D019208:Brain-Derived Neurotrophic Factor; D004337:Drug Carriers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate