Effects of titanium alloy particle on the expression of OPG in human osteoblasts in vitro

Objective To study the effects of particulate titanium alloy on expression of osteoprotegerin (OPG) gene in human osteoblasts in vitro so as to understand the mechanism of the periprosthetic osteolysis by wear debris during aseptic loosening. Methods Human bone marrow stromal cells (hBMSCs) were obtained and in- duced to differentiate and proliferate into osteoblasts which were identified by alkaline phosphatase dye. The 3-5th generations of human osteoblasts were cultured for three, six, and nine days after different concentrations of par- ticulate titanium alloy (1mg/mL, 0.1 mg/mL, 0. 01mg/mL) were added into the medium. The OPG gene ex- pression was quantified by RT-PCR. Results Most of the osteoblasts derived from hBMSCs had the stable growth feature and osteogenetic capability, and the alkaline phosphatase dye results were positive. All the different con- centrations of titanium particles suppressed OPG gene expression in osteoblasts and all the experimental groups had significant differences from the control group (P＜0. 01). Titanium particles of concentrations from 1mg/mL to 0. 01mg/mL showed inhibition on the expression of OPG in osteoblasts in a dose-and time-effective dependent manner. But the inhibitory effects of particles on the gene expression decreased gradually over a protracted period of time. Conclusion Titanium alloy particles decrease expression of OPG gene in human osteoblasts, and this may contribute to the differentiation of osteoclasts which may lead to the periprosthetic osteolysis.