Development of a Culture Chamber to test Drug Delivery Strategies for a Guided Neurite Outgrowth of Primary Auditory Neurons

Introduction Despite many improvements of cochlear implants (CI), the hearing impression is not comparable to physiological hearing. The CI-electrode in the scala tympani (ST) of the inner ear stimulates the neurons in the Rosenthal’s canal (RC), whereby an anatomical gap remains between electrode and neurons. To bridge this gap, a guided growth of neurites is needed, e.g. induced by neurotrophic factor release (NFR). Common in vitro-models for neurite regeneration research are mainly investigating dissociated cells and anatomical dimensions and drug delivery strategies are not included. We developed a chamber for the investigation of guided neurite outgrowth (neurite outgrowth chamber, NOC) of spiral ganglion explants (SGE) induced by NFR.

Methods NOCs are 3D-printed from polylactic acid (PLA). The design is based on the distance between RC and electrodes in the ST of human cochleae with a fivefold increased scale. The chambers consist of two compartments: adhesion area of SGE (RC-comp) and NFR area (ST-comp). The ST-comp includes a lateral inlet for NFR via mini-osmotic pumps over several weeks. A central channel connects both compartments and allows factor diffusion to the SGE. The chambers are fixed liquid tight with grease to glass coverslips. A co-cultivation of SGE with pumps can be performed for four NOCs at once in a modified 6-well plate.

Results The designed NOC is printable. The cultivation of SGE on glass coverslips in the chamber allows the direct observation of the effect of a pump-delivered factor on neurite outgrowth.

Outlook The NOC allows novel investigations of pharmacological substances e.g. regarding their biological effects and for the detection of effective concentrations and toxicity limits.

Publication History

Article published online:
10 June 2020