The influence on gene-expression profiling of osteoblasts behavior following treatment with the ionic products of sintered β-dicalcium pyrophosphate dissolution

Sintered dicalcium pyrophosphate (SDCP) is biocompatible to bone tissue both in the in vivo and in vitro model. However, the molecular mechanisms that mediated these processes have yet to be identified. In this study, we investigated the influence of SDCP ions on in vitro osteoblasts behavior. The powder of sintered beta-dicalcium pyrophosphate (SDCP) was dissolved by HCl and then diluted into different concentration of solutions by culture medium used in the osteoblast cell culture. The effects of various concentration of SDCP on bone cell activities were evaluated by using MTT assay. For the differentiation of osteoblasts, alkaline phosphatase (AP) staining, von Kossa stain for mineralized nodules and bone markers messenger ribonucleic acid (mRNA) isolation and identification were performed at 3 h, days 1, 3 7 and 14. In the presence of 10(-8) M SDCP for 14 days, the osteoblasts population was still significantly higher than that of control. In the qualitative analysis for the formation of AP staining colonies and mineralization nodules formation were not affected by SDCP ions. When osteoblasts cultured in the presence of 10(-8) M SDCP ions, the osteocalcin mRNA expression was up-regulated; while the collagen, osteonectin and osteopontin mRNA expression were down-regulated. In this study, we demonstrated that the elevated concentration of calcium and pyrophosphate ions can activate genes of the bone cells. This study will contribute to a better understanding of cell/biomaterial interactions and mechanisms that SDCP affect the bone cells. (C) 2003 Elsevier Ltd. All rights reserved.