Co-Cr-Mo alloy particles induce tumor necrosis factor alpha production in MLO-Y4 osteocytes: A role for osteocytes in particle-induced inflammation

Arihiko Kanaji, Marco S. Caicedo, Amarjit S. Virdi, D. Rick Sumner, Nadim J. Hallab, Kotaro Sena

Research output: Contribution to journalArticle

48 Citations (Scopus)


Wear debris-induced osteolysis is purportedly the limiting problem affecting the long term results of joint arthroplasty. Pathogenic effects of wear debris in peri-implant cells such as macrophages, osteoblasts and osteoclasts have been well studied. In contrast, the effects of wear debris on osteocytes, which make up over 90% of all bone cells, remain unknown. We hypothesized that metal implant debris can induce the pro-inflammatory response in osteocytes. This study demonstrated the effects of cobalt-chromium-molybdenum alloy (Co-Cr-Mo) particles on a well-characterized MLO-Y4 osteocyte cell line. Co-Cr-Mo alloy particle treatment significantly (p < 0.05) up-regulated tumor necrosis factor alpha (TNFα) gene expression after 3 and 6 h and TNFα protein production after 24 h, but down-regulated interleukin-6 (IL-6) gene expression after 6 h. Co-Cr-Mo alloy particle treatment also induced osteocyte apoptosis after 24 h. This apoptotic effect was partially (40%) dependent on TNFα. Therefore, our results suggest that osteocytes play a role in particle-induced inflammation and bone resorption following total joint arthroplasty by inducing pro-inflammatory cytokines and inducing osteocyte apoptosis.

Original languageEnglish
Pages (from-to)528-533
Number of pages6
Issue number3
Publication statusPublished - 2009 Sep 1



  • MLO-Y4 cell
  • Osteocyte apoptosis
  • Osteolysis
  • Tumor necrosis factor α
  • Wear debris

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Histology

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