title: Influence of particle size and reactive oxygen species on cobalt chrome nanoparticle-mediated genotoxicity.
abstract: Patients with cobalt chrome (CoCr) metal-on-metal (MOM) implants may be exposed to a wide size range of metallic nanoparticles as a result of wear. In this study we have characterised the biological responses of human fibroblasts to two types of synthetically derived CoCr particles [(a) from a tribometer (30 nm) and (b) thermal plasma technology (20, 35, and 80 nm)] in vitro, testing their dependence on nanoparticle size or the generation of oxygen free radicals, or both. Metal ions were released from the surface of nanoparticles, particularly from larger (80 nm) particles generated by thermal plasma technology. Exposure of fibroblasts to these nanoparticles triggered rapid (2 h) generation of reactive oxygen species (ROS) that could be eliminated by inhibition of NADPH oxidase, suggesting that it was mediated by phagocytosis of the particles. The exposure also caused a more prolonged, MitoQ sensitive production of ROS (24 h), suggesting involvement of mitochondria. Consequently, we recorded elevated levels of aneuploidy, chromosome clumping, fragmentation of mitochondria and damage to the cytoskeleton particularly to the microtubule network. Exposure to the nanoparticles resulted in misshapen nuclei, disruption of mature lamin B1 and increased nucleoplasmic bridges, which could be prevented by MitoQ. In addition, increased numbers of micronuclei were observed and these were only partly prevented by MitoQ, and the incidence of micronuclei and ion release from the nanoparticles were positively correlated with nanoparticle size, although the cytogenetic changes, modifications in nuclear shape and the amount of ROS were not. These results suggest that cells exhibit diverse mitochondrial ROS-dependent and independent responses to CoCr particles, and that nanoparticle size and the amount of metal ion released are influential.
authors: Bristol Implant Research Centre, Avon Orthopaedic Centre, Southmead Hospital, Bristol, UK. raghunathan@ucdavis.edu
authors: Vijay Krishna
authors: VK
authors: Raghunathan
authors: Michael
authors: M
authors: Devey
authors: Sue
authors: S
authors: Hawkins
authors: Lauren
authors: L
authors: Hails
authors: Sean A
authors: SA
authors: Davis
authors: Stephen
authors: S
authors: Mann
authors: Isaac T
authors: IT
authors: Chang
authors: Eileen
authors: E
authors: Ingham
authors: Ashraf
authors: A
authors: Malhas
authors: David J
authors: DJ
authors: Vaux
authors: Jon D
authors: JD
authors: Lane
authors: Charles P
authors: CP
authors: Case
mesh_terms: D002478:Cells, Cultured; D002858:Chromium Alloys / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000633:toxicity* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D010316:Particle Size; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D002858:Chromium Alloys; D017382:Reactive Oxygen Species; D003035:Cobalt