Alginate is a suitable matrix for BDNF-release and neuroprotection in the inner ear

Introduction To achieve good performance with a cochlear implant (CI), a high number of spiral ganglion neurons (SGN) is a prerequisite. Treatment with growth factors like brain-derived neurotrophic factor (BDNF) is known to support the survival of SGN. Up to now, a clinically feasible approach for, especially chronic, release of such factors to the inner ear is still missing. Therefore, the suitability of alginate hydrogel as a matrix for BDNF-release was investigated and the neuroprotective effect was analyzed.

Methods BDNF (100 μg/ml) was mixed with the alginate sol at a ratio of 1:1, while the negative control (NC) contained no factor. The alginate-mix was cross-linked by ionic gelation with BaCl₂  to form beads or to apply it as hydrogel-coating to a dummy-electrode. BDNF-release was performed in artificial perilymph at 37°C in an incubator, with the medium being changed daily in the first week and subsequently weekly. The supernatants were examined for their BDNF-content by ELISA-detection and for their neuroprotective effect in the SGN culture. Stability of the gel was analyzed with microscopic images.

Results BDNF was released from the alginate over several weeks and showed a neuroprotective effect in the SGN culture when compared to the NC. The stability of the alginate gel was not negatively affected by mixing with BDNF. Outlook: The release of BDNF using alginate as delivery matrix showed promising potential in the performed study. BDNF can be released from potentially implantable beads as well as from a coating of the CI electrode for neuroprotection in the inner ear.

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Artikel online veröffentlicht:
12. Mai 2023