Proinflammatory cytokine expression of IL-1 beta and TNF-alpha by human osteoblast-like MG-63 cells upon exposure to silicon nitride in vitro

This study was designed to determine the effect of Si3N4 disks and particul ates on human osteoblast-like MG-63 cells in vitro. The MG-63 (10(5)/mL) ce lls were plated onto 24-well polystyrene plates fitted with either sintered reaction-bonded (SRBSN) or reaction-bonded (RBSN) 15-mm disks. Controls co nsisted of wells without Si3N4 disks. Cells propagated at 37 degrees C, 5% CO2 for 48 h on Si3N4 disks and control polystyrene surfaces exhibited simi lar proliferative capacities (7000 and 4000 cpm/10(5) cells, respectively, p > 0.05). Cells incubated with 1, 10, or 100 mu g/ml of Si3N4 particles (< 1.00 to 5.00 mu m) for 24 h did not exhibit a decrease in DNA synthetic act ivity: 12 +/- 1.3 x 10(4), 10.5 +/- 1.5 x 10(4), and 11.0 +/- 1.7 x 10(4) c pm, respectively, compared to 11.6 +/- 2.6 x 10(4) cpm/10(5) for the contro l cells, as indicated by H-3-thymidine uptake. Cells propagated on RBSN dis played increased expression of cytokines IL-1 beta and TNF-alpha compared t o the control cells, as shown by reverse transcriptase-polymerase chain rea ction (RT-PCR). in contrast, cells propagated on SRBSN surfaces expressed t he same level of IL-1 beta and TNF-alpha as that of control cells, incubati on of MG-63 cells with 1-10 mu g/mL of particles did not increase IL-1 beta expression. However, at 100 mu g/mL, TNF-alpha expression was greater than that of the control cells. Silicon nitride, evaluated here as disks or as particulates (1-10 mu g/mL), is biocompatible and does not hinder the proli feration or induce proinflammatory cytokine expression of human osteoblastl ike MG-63 cells in vitro. (C) 2000 John Wiley & Sons, Inc.