ACTIVATION OF OSTEOCLAST-MEDIATED BONE-RESORPTION BY THE SUPERNATANT FROM A RABBIT SYNOVIAL CELL-LINE IN RESPONSE TO POLYETHYLENE PARTICLES

It is unknown whether the soluble factors produced from cells activate d by wear particles in the fibrous tissue around failed joint prosthes es really activate osteoclastic bone resorption. In this study, the ac tivation of osteoclast-mediated bone resorption by the products from a rabbit synovial cell line (HIG-82) stimulated by various particles wa s investigated using rabbit unfractionated bone cells cultured on a de ntin slice. The HIG cells were challenged with the following laborator y-made particles: high-density polyethylene (PE), cobalt alloy (Co-Cr) , titanium alloy (Ti6Al4V), pure titanium (Ti), and sintered hydroxyap atite (HA). The size of each particle was <2 mu m. The supernatants fr om HIG cells cultured with the appropriate concentration of wear parti cles were added to unfractionated bone cells on a dentin slice, and th en resorbed areas were determined for each particle. Interestingly, re sorbed areas significantly increased only when the culture medium from HIG cells with PE particles was added to unfractionated bone cells. T his 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 sens itively to evaluate the effects of soluble factors from the cells stim ulated by particulate biomaterials from joint prostheses on osteoclast ic bone resorption. (C) 1996 John Wiley & Sons, Inc.