Neurite regeneration of primary auditory neurons in hydrogelsExzellenzcluster "Hearing4all" (EXC 1077/1)
23 April 2019 (online)
To bridge the gap between the spiral ganglion neurons (SGN) of the auditory nerve and the cochlear implant (CI)-electrode is considered as an important prerequisite for improvement of the nerve-electrode-interface. To enable a direct contact between neurites and electrode-contacts, a support of neurite growth through the fluid-filled scala tympani is necessary. Therefore, different hydrogels were tested.
Alginate and chitosan of different viscosities serving as growth matrix for SGN-neurites and a combination with neuritogenic factors (NF) were investigated in vitro. SGN-explants of neonatal rats were harvested and cultured for 5 days in alginate or on chitosan. Different viscosities of the hydrogels were achieved for the alginate by different compositions and polymerization and for the chitosan by different concentrations (0.7 – 2%). 50 ng/ml BDNF, 100 ng/ml CNTF and a combination of both were added as NF. 10% serum (positive control, chitosan) and no additives (negative control) served as controls. Number and length of regenerated neurites in and on the gels were analyzed.
For a stiff alginate the significant highest number (strongly crosslinked) and length (softly crosslinked) of regenerated neurites was detected. In all chitosan concentrations an attachment of the explants was achieved and only chitosan of 2% did not support a neurite outgrowth. An addition of NF, especially CNTF, increased the neurite outgrowth.
Alginate and chitosan show, especially in combination with neuritogenic factors, a promising potential as matrix for regenerating neurites to close the gap between the CI-electrode and the SGN.