Activation of osteoclast-mediated bone resorption by the supernatant from a rabbit synovial cell line in response to polyethylene particles

Abstract

It is unknown whether the soluble factors produced from cells activated by wear particles in the fibrous tissue around failed joint prostheses really activate osteoclastic bone resorption. In this study, the activation of osteoclast-mediated bone resorption by the products from a rabbit synovial cell line (HIG-82) stimulated by various particles was investigated using rabbit unfractionated bone cells cultured on a dentin slice. The HIG cells were challenged with the following laboratory-made particles: high-density polyethylene (PE), cobalt alloy (Co-Cr), titanium alloy (Ti6Al4V), pure titanium (Ti), and sintered hydroxyapatite (HA). The size of each particle was < 2 microns. The supernatants from HIG cells cultured with the appropriate concentration of wear particles were added to unfractionated bone cells on a dentin slice, and then resorbed areas were determined for each particle. Interestingly, resorbed areas significantly increased only when the culture medium from HIG cells with PE particles was added to unfractionated bone cells. This study demonstrates that PE particles stimulate the rabbit synovial cells to produce soluble factors that induce osteoclast-mediated bone resorption. Moreover, this experimental model is a useful method sensitively to evaluate the effects of soluble factors from the cells stimulated by particulate biomaterials from joint prostheses on osteoclastic bone resorption.