Polydimethylsiloxanes biocompatibility in PC12 neuronal cell line

Area of Science:

• Biomaterials Science
• Neuroscience
• Otolaryngology

Background:

• Cochlear implants are crucial for severe/profound hearing loss but can cause adverse reactions.
• Silicone electrode coatings may lead to spiral ganglion cell apoptosis and necrosis.

Purpose of the Study:

• Evaluate the in vitro toxicity of three polydimethylsiloxane (PDMS) compounds on neuronal cells.
• Determine if PDMS compounds used in cochlear implant electrodes induce apoptosis or necrosis.

Main Methods:

• PC12 neuronal cells were exposed to varying dilutions of hexadimethylsiloxane, octamethyltrisiloxane, and decamethylcyclopentasiloxane for up to 6 days.
• Assessed cell viability, morphology (neurite number and length), and apoptotic marker mRNA expression.
• Compared PDMS effects to controls exposed to silicone or glass rods.

Main Results:

• Hexadimethylsiloxane and octamethyltrisiloxane reduced cell viability at high concentrations across all time points.
• Decamethylcyclopentasiloxane reduced cell viability from 72 hours onwards.
• Neurite number and length were reduced by octamethyltrisiloxane and decamethylcyclopentasiloxane, and neurite length by hexadimethylsiloxane.
• No significant changes in apoptotic markers were observed, suggesting biocompatibility.

Conclusions:

• PDMS compounds did not induce apoptosis in PC12 cells, indicating biocompatibility.
• Observed reductions in cell viability and neurite growth are likely due to PDMS film formation inhibiting air exchange, not cytotoxicity.
• Further research should consider the physical effects of PDMS surface films on neuronal cells in vitro.