Ultrahigh molecular weight polyethylene (UHMWPE) has been used for many years as a bearing surface in total joint replacement (TJR). However, late-state failure in TJR is predominantly caused by osteolysis mediated by wear particles. We tested our hypothesis that UHMWPE nanoparticles are important determinants in activating dendritic cells (DCs). UHMWPE wear particles generated from a knee simulator were profiled using an atomic force microscopy and fractionated into six fractions: 0.05-0.2, 0.2-0.8, 0.8-1, 1-5, 5-10, and 10-20 micrometer. Effects of each fraction, a mixture of nano-sized fractions, and a mixture of all fractions on the activation of mice spleen DCs were determined using flow cytometry with specific antibodies of anti-CD11c-APC, anti-CD80-PE, anti-CD11b-PerCp, anti-CD86-Biotin and streptavidin-FITC. Supernatant from DCs treated with wear particles were assayed for IL-1beta, IL-6, IL-12/23, TNF-alpha and IFN-gamma. Activation of human osteoclasts (OCs) by wear particles were determined using TRAP stain.Aim
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