These findings indicate that local rhIGF-1 treatment via gelatin hydrogels is effective for treatment of NIHL.

Objective: Previous studies have demonstrated the potential of cell transplantation for regeneration of spiral ganglion neurons (SGNs). However, the effect of surgical invasion on host cochleae has yet to be evaluated. The present study investigated the efficiency and invasiveness of our surgical procedure using a fine glass pipette for injections into the cochlear modiolus. Methods: We examined the survival of transplanted embryonic stem cell-derived neurons in the cochlear modiolus of guinea pigs. Surgical invasiveness was assessed by measurements of electrically evoked auditory brainstem responses (eABRs) and SGN densities after an injection of 5 ml of saline into the cochlear modiolus. Results: All of the transplanted animals exhibited localization of transplanted cells in the cochlear modiolus. No significant alterations in the eABR thresholds or SGN densities were found following surgery. Conclusion: These findings indicate that our procedure is a viable method for testing the potential of transplants for SGN replacement.