title: Effects of CoCr metal wear debris generated from metal-on-metal hip implants and Co ions on human monocyte-like U937 cells.
abstract: Hip resurfacing with cobalt-chromium (CoCr) alloy was developed as a surgical alternative to total hip replacement. However, the biological effects of nanoparticles generated by wear at the metal-on-metal articulating surfaces has limited the success of such implants. The aim of this study was to investigate the effects of the combined exposure to CoCr nanoparticles and cobalt ions released from a resurfacing implant on monocytes (U937 cells) and whether these resulted in morphology changes, proliferation alterations, toxicity and cytokine release. The interaction between prior exposure to Co ions and the cellular response to nanoparticulate debris was determined to simulate the situation in patients with metal-on-metal implants receiving a second implant. Effects on U937 cells were mainly seen after 120h of treatment. Prior exposure to Co ions increased the toxic effects induced by the debris, and by Co ions themselves, suggesting the potential for interaction in vivo. Increased TNF-α secretion by resting cells exposed to nanoparticles could contribute to osteolysis processes in vivo, while increased IFN-γ production by activated cells could represent cellular protection against tissue damage. Data suggest that interactions between Co ions and CoCr nanoparticles would occur in vivo, and could threaten the survival of a CoCr metal implant.
authors.affiliation: Biomedical Engineering Department, University of Strathclyde, Wolfson Centre, Glasgow G4 0NW, UK. Electronic address: O.M.PosadaEstefan@leeds.ac.uk.
authors.forename: Olga M
authors.initials: OM
authors.lastname: Posada
authors.affiliation: Strathclyde Institute for Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow G4 0RE, UK. Electronic address: r.j.tate@strath.ac.uk.
authors.forename: Rothwelle J
authors.initials: RJ
authors.lastname: Tate
authors.affiliation: Biomedical Engineering Department, University of Strathclyde, Wolfson Centre, Glasgow G4 0NW, UK. Electronic address: m.h.grant@strath.ac.uk.
authors.forename: M Helen
authors.initials: MH
authors.lastname: Grant
mesh_terms: D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002858:Chromium Alloys / Q000633:toxicity*; D003035:Cobalt / Q000633:toxicity*; D006622:Hip Prosthesis; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D053768:Metal Nanoparticles / Q000633:toxicity*; D009000:Monocytes; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells
chemical_list: D002858:Chromium Alloys; C508600:IL6 protein, human; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D003035:Cobalt; D007371:Interferon-gamma
keywords: Cobalt–chrome alloy; Hip replacements; Metal ions; Metal wear debris; Monocytes; Nanoparticles