Biological effects of cobalt-chromium nanoparticles and ions on dural fibroblasts and dural epithelial cells

The introduction of metal-on-metal total disc replacements motivated studies to evaluate the effects of cobalt-chromium (CoCr) nanoparticles on cells of the dura mater. Porcine fibroblasts and epithelial cells isolated from the dura mater were cultured with clinically-relevant CoCr nanoparticles and the ions, generated by the particles over 24 h, at doses up to 121 μm³per cell. Cell viability and production of proinflammatory cytokines was assessed over 4 days. The capacity of the particles to induce oxidative stress in the cells was evaluated at 24 h. The CoCr particles and their ions significantly reduced the viability of the dural epithelial cells in a dose-dependent manner but not the fibroblasts. Both cell types secreted IL-8 in response to particle exposure at doses of 60.5 μm³ (epithelial cells) and 121 μm³ (fibroblasts, epithelial cells) per cell. No significant release of IL-6 was observed in both cell types at any dose. Reactive oxygen species were induced in both cell types at 50 μm³ per cell after 24 h exposure. The data suggested novel differences in the resistance of the dural epithelial cells and fibroblasts to CoCr nanoparticle/ion toxicity and demonstrated the inflammatory potential of the particles. The data contributes to a greater understanding of the potential biological consequences of the use of metal-on-metal total disc prostheses.