Sintered β-dicalcium phosphate particles induce intracellular reactive oxygen species in rat osteoblasts

Osteolysis was usually associated with the wear particles from biomaterials used in the artificial joint, but the mechanism is not well known. This study was aimed to investigate the effects of sintered β-dicalcium phosphate (SDCP) particles on induction of intracellular reactive oxygen species and on inhibition of cell viability and alkaline phosphatase activity in rat calvarial osteoblasts. Analysis of cell viability revealed that smaller particles of SDCP caused more cell death, and the effect was time-dependent. Treatment of the osteoblastic cells with SDCP particles of various sizes resulted in decrease of alkaline phosphatase activity, and the suppressive effect was dependent on particle sizes and treating time intervals. SDCP particles induced the production of intracellular reactive oxygen species in rat osteoblasts. The wear particles of SDCP with smaller sizes induced more intracellular reactive oxygen species of osteoblasts. The present study is the first report to identify that the particles of SDCP could induce oxidative stress in osteoblastic cells. From these data we propose that intracellular reactive oxygen species induced by SDCP particles may be involved in SDCP particles-caused cell death and decrease of alkaline phosphatase activity in rat osteoblasts.