• Habibovic, Pamela
• Patntirapong, Somying
• Hauschka, Peter V.

Abstract

<p>Metal ions Originating from mechanical debris and Corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+) which is a major component of cobalt-chromium-based implant alloys and a known activator of osteolysis, are incorporated into the mineral phase of bone. We hypothesize that the accumulation of CO2+ in the mineral could directly activate osteolysis by targeting osteoclasts. To test this hypothesis, we coated tissue culture plastic with a thin layer of calcium phosphate (CaP) containing added traces Co2+ thereby mimicking the bone mineral accumulation of Co2+. Murine bone marrow osteoclasts formed in the presence of M-CSF and RANKL were cultured on these surfaces to examine the effects of Co2+ on osteoclast formation and resorptive activity. Treatment conditions with Co2+ involved incorporation into the Cap layer, adsorption to the mineral Surface, or addition to Culture media. Micromolar concentrations of Co2+ delivered to developing osteoclast Precursors by all 3 routes increased both osteoclast differentiation and resorptive function. Compared to CaP layers without Co2+, we observed a maximal 75% increase in osteoclast numbers and a 2.3- to 2.7-fold increase in mineral resorption from the tissue culture wells containing 0.1 mu m Co2+ and 0.1 - 10 mu m Co2+, respectively. These concentrations are well within the range found in peri-implant tissues in vivo. This direct effect of Co2+ on osteoclasts appears to act independently of the particulate phagocytosis/inflammation-mdiated pathways, thus enhancing osteolysis and aseptic implant loosening. (C) 2008 Elsevier Ltd. All rights reserved.</p>

Topics

• impedance spectroscopy
• mineral
• surface
• polymer
• chromium
• phase
• cobalt
• activation
• Calcium