Can zinc protect cells from the cytotoxic effects of cobalt ions and nanoparticles derived from metal-on-metal joint arthroplasties?

OBJECTIVES: Recently, high failure rates of metal-on-metal (MOM) hip implants have raised concerns of cobalt toxicity. Adverse reactions occur to cobalt nanoparticles (CoNPs) and cobalt ions (Co(2+)) during wear of MOM hip implants, but the toxic mechanism is not clear. METHODS: To evaluate the protective effect of zinc ions (Zn(2+)), Balb/3T3 mouse fibroblast cells were pretreated with 50 μM Zn(2+) for four hours. The cells were then exposed to different concentrations of CoNPs and Co(2+) for four hours, 24 hours and 48 hours. The cell viabilities, reactive oxygen species (ROS) levels, and inflammatory cytokines were measured. RESULTS: CoNPs and Co(2+) can induce the increase of ROS and inflammatory cytokines, such as tumour necrosis factor α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). However, Zn pretreatment can significantly prevent cytotoxicity induced by CoNPs and Co(2+), decrease ROS production, and decrease levels of inflammatory cytokines in Balb/3T3 mouse fibroblast cells. CONCLUSION: These results suggest that Zn pretreatment can provide protection against inflammation and cytotoxicity induced by CoNPs and Co(2+) in Balb/3T3 cells. Cite this article: Y. Liu, H. Zhu, H. Hong, W. Wang, F. Liu. Can zinc protect cells from the cytotoxic effects of cobalt ions and nanoparticles derived from metal-on-metal joint arthroplasties? Bone Joint Res 2017;6:649–655. DOI: 10.1302/2046-3758.612.BJR-2016-0137.R2.