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Third-party-funded project

Interaction of spiral ganglion neuron processes with alloplastic materials

Project management at the University of Würzburg:

Participating scientists:

The cochlear implant (CI) involves the introduction of alloplastic materials into the cochlea. While current implants interact with cochlear neurons at a distance, direct interactions between spiral ganglion (SG) neurites and implants could be fostered by appropriate treatment with neurotrophic factors. The interactions of fibroblasts and osteoblasts with alloplastic materials have been well studied in vitro and in vivo. However, interactions of inner ear neurons with such alloplastic materials have yet to be described. To investigate survival and growth behavior of SG neurons on different materials, SG explants from P5 rat SG were cultured for 72 hours in the presence of Neurotrophin-3 (NT-3)(10 ng/ml) on titanium, gold, stainless steel, platinum, silicone and plastic surfaces that had been coated with laminin (LN) and poly-L-lysine (PLL). Neurite outgrowth was investigated after immune-histological staining for neurofilament, by image analysis to determine neurite extension and directional changes. Neurite morphology and adhesion to the alloplasic material was also evaluated by scanning electron microscopy (SEM). On titanium, SG neurites reached the highest extend of outgrowth, with an average length of 662 µm and a mean of 31 neurites per explant, compared to 568 µm and 21 neurites on gold, 574 µm and 24 neurites on stainless steel, 509 µm and 16 neurites on platinum, 281 µm and 12 neurites on silicone and 483 µm and 31 neurites on plastic. SEM revealed details of adhesion of neurites and interaction with non-neuronal cells. The results of this study indicate that the growth of SG neurons in vitro is strongly influenced by alloplastic materials, with titanium exhibiting the highest degree of biocompatibility with respect to neurite extension. The knowledge of neurite interaction with different alloplastic materials is of clinical interest, as developments in cochlear implant technology lead to closer contact of implanted electrodes with surviving inner ear neurons. For example, differential growth on titanium versus silicone could be useful in segregating neurites to the different electrodes of a multi-channel device.

Key words:
    alloplastic material
    spiral ganglion
    neurite growth
    cochlear implant

Projekt period: from 07.1999 to 04.2001

Funding institution:
Sondermittel Land Bayern