The osteolytic response of macrophages to challenge with particles of Simplex P, Endurance, Palacos R, and Vertebroplastic bone cement particles in vitro

Abstract

The capacity of clinically relevant wear particles from Simplex P, Endurance, Vertebroplastic and Palacos R bone cements to activate macrophages to produce cytokines and bone resorbing activity in vitro was compared. Cement particles were generated aseptically by using a pin on plate rig. The particles were irregular in shape, and there were no significant differences in the particle characteristics of the different bone cement types (mean equivalent circle diameter range 0.225--0.36 mum, mean area range 0.048--0.063 microm(2), mean aspect ratio range 1.481--1.593, and mean length 0.412--0.523 microm). The volumetric concentration of particles in the 0.1- to 1.0-microm size range was 85% Palacos R, 82% Endurance, 80% Simplex P, and 77% Vertebroplastic. Particles were cultured with C3H macrophages at 100 microm(3) per cell for 24 h. Cytokines were determined by enzyme-linked immunosorbent assay and bone resorption (BR) measured by Ca(45) release from murine calvarias. Particles of Palacos R and Endurance stimulated enhanced production of TNF-alpha, IL-1-beta, and IL-6 (p<0.05; ANOVA). Simplex P particles only stimulated IL-1-beta (p<0.05; ANOVA). Vertebroplastic particles did not stimulate production of any of the cytokines. Particles of Palacos R generated the highest BR (1.38), but this did not reach statistical significance. The BRs for the other bone cements were no greater than the control. Hence, compared with the same volumetric concentrations, particles of Palacos R and Endurance were the most, and particles of Vertebroplastic were the least biologically reactive.