gms | German Medical Science

Long-term drug delivery to the inner ear may be achieved by functionalization of cochlear implant electrodes with cells providing neurotrophic factors to the spiral ganglion cells (SGC). In a previous study we demonstrated survival of NIH3T3/BDNF cells on model electrode surfaces, release of bioactive BDNF and protection of SGC in vitro. Aim of the present study was to investigate a potential neuroprotective effect of such modified model electrodes in vivo on deafened guinea pigs.

Lentivirally modified NIH3T3 cells producing green fluorescent protein and brain-derived neurotrophic factor (BDNF) were seeded on round silicone model electrodes (ME) at a density of 1,75x104 cells/ME and allowed to adhere and proliferate for 7 days in 48-well plates. Cell-coated model electrodes were then implanted unilaterally into the inner ear of deafened guinea pigs. The contralateral deafened but untreated ears served as controls. Animals were sacrificed 30 days after implantation, electrodes were explanted and cochleae were histologically evaluated for SGC density. A significantly increased density of SGC was observed in the treated implanted side (5.85±1.07; mean values±standard error of mean) when compared to the contralateral untreated side (4.12±1.07; p<0.01). Our data demonstrated that cell-coated model electrodes used for the local delivery of BDNF to the inner ear of guinea pigs significantly protected SGC from degeneration after ototoxic deafening.