Interaction of spiral ganglion neuron processes with alloplastic materials in vitro(1).
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 post-natal day 5 rat SG were cultured for 72 h in the presence of neurotrophin-3 (10 ng/ml) on titanium, gold, stainless steel, platinum, silicone and plastic surfaces that had been coated with laminin and poly-L-lysine. Neurite outgrowth was investigated after immunohistological staining for neurofilament, by image analysis to determine neurite extension and directional changes. Neurite morphology and adhesion to the alloplastic material were also evaluated by scanning electron microscopy (SEM). On titanium, SG neurites reached the highest extent of outgrowth, with an average length of 662 microm and a mean of 31 neurites per explant, compared to 568 microm and 21 neurites on gold, 574 microm and 24 neurites on stainless steel, 509 microm and 16 neurites on platinum, 281 microm and 12 neurites on silicone and 483 microm 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 development in CI technology leads to closer contact of implanted electrodes with surviving inner ear neurons.
Department of Otorhinolaryngology, Head and Neck Surgery, Bayerische Julius Maximilians Universität, 97080 Würzburg, Germany.
Dominik
D
Brors
Christoph
C
Aletsee
Konrad
K
Schwager
Robert
R
Mlynski
Stefan
S
Hansen
Maria
M
Schäfers
Allen F
AF
Ryan
Stefan
S
Dazert
D000818:Animals; D000831:Animals, Newborn; D001672:Biocompatible Materials; D002455:Cell Division; D002470:Cell Survival; D003054:Cochlear Implants; D006046:Gold; D066298:In Vitro Techniques; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D016501:Neurites / Q000502:physiology / Q000648:ultrastructure; D010969:Plastics; D010984:Platinum; D051381:Rats; D017207:Rats, Sprague-Dawley; D012828:Silicones; D013136:Spiral Ganglion / Q000166:cytology* / Q000502:physiology*; D013193:Stainless Steel; D014025:Titanium
D001672:Biocompatible Materials; D010969:Plastics; D012828:Silicones; D013193:Stainless Steel; D010984:Platinum; D006046:Gold; D014025:Titanium