Platinum corrosion products from electrode contacts of human cochlear implants induce cell death in cell culture models
Creators: name: Wissel, Kirsten
name: Brandes, Gudrun
name: Pütz, Nils
name: Angrisani, Gian Luigi
name: Thieleke, Jan
name: Lenarz, Thomas
name: Durisin, Martin
Publisher: name: San Francisco, CA : Public Library of Science
Year: 2018
Subjects: subject: metal nanoparticle
subject: platinum
subject: animal
subject: cell culture technique
subject: cell death
subject: cell survival
subject: chemistry
subject: cochlea prosthesis
subject: cochlear implantation
subject: corrosion
subject: drug effect
subject: electrode
subject: endocytosis
subject: endoplasmic reticulum
subject: human
subject: mitochondrion
subject: mouse
subject: NIH 3T3 cell line
subject: procedures
subject: tumor cell line
subject: Animals
subject: Cell Culture Techniques
subject: Cell Death
subject: Cell Line, Tumor
subject: Cell Survival
subject: Cochlear Implantation
subject: Cochlear Implants
subject: Corrosion
subject: Electrodes
subject: Endocytosis
subject: Endoplasmic Reticulum
subject: Humans
subject: Metal Nanoparticles
subject: Mice
subject: Mitochondria
subject: NIH 3T3 Cells
subject: Platinum
subject: Dewey Decimal Classification::600 | Technik::610 | Medizin, Gesundheit

description: Despite the technological progress made with cochlear implants (CI), impedances and their diagnosis remain a focus of interest. Increases in impedance have been related to technical defects of the electrode as well as inflammatory and/or fibrosis along the electrode. Recent studies have demonstrated highly increased impedances as the result of corroded platinum (Pt) electrode contacts. This in vitro study examined the effects of Pt ions and compounds generated by corrosion of the electrode contacts of a human CI on cell metabolism. Since traces of solid Pt in surrounding cochlear tissues have been reported, the impact of commercially available Pt nanoparticles (Pt-NP, size 3 nm) on the cell culture model was also determined. For this purpose, the electrode contacts were electrically stimulated in a 0.5% aqueous NaCl solution for four weeks and the mass fraction of the platinum dissolute (Pt-Diss) was determined by mass spectrometry (ICP-MS). Metabolic activity of the murine fibroblasts (NIH 3T3) and the human neuroblastoma (SH-SY5Y) cells was determined using the WST-1 assay following exposure to Pt-Diss and Pt-NP. It was found that 5-50 μg/ml of the Pt-NP did not affect the viability of both cell types. In contrast, 100 μg/ml of the nanoparticles caused significant loss in metabolic activity. Furthermore, transmission electron microscopy (TEM) revealed mitochondrial swelling in both cell types indicating cytotoxicity. Additionally, TEM demonstrated internalized Pt-NP in NIH 3T3 cells in a concentration dependent manner, whereas endocytosis in SH-SY5Y cells was virtually absent. In comparison with the Pt-NP, the corrosion products (Pt-Diss) with concentrations between 1.64 μg/ml and 8.2 μg/ml induced cell death in both cell lines in a concentration dependent manner. TEM imaging revealed both mitochondrial disintegration and swelling of the endoplasmic reticulum, suggesting that Pt ions trigger cytotoxicity in both NIH 3T3 and SH-SY5Y cell lines by interacting with the respiratory chain.