Production of TNF-alpha and bone resorbing activity by macrophages in response to different types of bone cement particles

We have compared the capacity of clinically relevant wear debris from seven different cement types to activate macrophages to produce TNF-alpha, IL-1 beta, IL-6 and bone resorbing activity in vitro. The bone cements were: CMW 1 original (PMMA only); CMW 1RO (1 mu m BaSO4; 9.2%); CMW copolymer bone c ement 1 (10 mu m BaSO4; 10%); CMW copolymer bone cement 2 (1 mu m BaSO4; 10 %); Palaces R (10 mu m ZrO2; 15.6%); CMW Calcium phosphate cement 20% (10 m u m tri-calcium phosphate: 20%) and CMW calcium phosphate cement 30% (10 mu m tri-calcium phosphate; 30%). Cement debris was produced aseptically usin g a simple configuration wear test. The majority of particles were in the s ize range 0.1-0.5 mu m for each cement type. The cement particles were co-c ultured with the U937 macrophage cell line at ratios of 10 and 100 mu m(3) particle volumes to macrophage cell numbers for 24 h. At the 10 : 1 ratio t he particles had no effect on the cells. At the 100:1 ratio, the major cyto kine produced was TNF-alpha and there were no statistical differences betwe en the different types of cement debris. The bone resorption activity of th e co-culture supernatants was significantly greater than the control (U937 cells without particles) for particles of CMW 1RO, CMW copolymer bone cemen t 1, CMW copolymer bone cement 2 and Palaces R (P < 0.05, ANOVA). However t here were no statistical differences between the levels of bone resorption evoked by these four cement types. The CMW1 original and CMW calcium phosph ate containing cements failed to induce the macrophages to elaborate bone r esorption activity at the 100 : 1 ratio. These data suggest that the additi on of radio-opaque additives to bone cement may increase the capacity of th e debris to induce osteolysis. (C) 2000 Elsevier Science Ltd. All rights re served.