Influences of ionic dissolution products of dicalcium silicate coating on osteoblastic proliferation, differentiation and gene expression

This work aims to explore the influence of the ionic products of dicalcium silicate coating on osteoblastic proliferation and differentiation, as well as on the expression of BMP2 and its signal transducers Smad1, 6 and 7 in MG-63 osteoblast-like cells. Plasma-sprayed dicalcium silicate coatings were soaked in DMEM to obtain culture media containing the ionic dissolution products of dicalcium silicate coating (Ca2SiO4–DMEM). MG63 osteoblast-like cells were cultured in Ca2SiO4–DMEM (experimental group) for 3–12 days, while those cultured in normal DMEM served as control (control group). MTT assay was used to evaluate cell viability and proliferation. Alkaline phosphatase activity (ALP), osteocalcin (OC) and type I collagen (COLI) were investigated as differentiation markers. Gene expression of BMP2 and Smad1, 6, 7 was also detected. BMP2 protein was examined by ELISA assay. Alizarin Red-S (AR-S) assay was used to detect mineralization. The results demonstrated that Si concentration in Ca2SiO4–DMEM is markedly higher than that in normal DMEM. Compared to the control group, MG63 cells of the experimental group exhibited upregulated proliferation on day 3, and markedly upregulated gene expression of the differentiation markers, especially on days 9 and 12 for OC and on days 3, 6 and 9 for ALP. Gene expression of BMP2 and Smad1, as well as BMP2 protein secreted into culture media, was also upregulated in the experimental group, while gene expression of Smad6 and 7 was not influenced. AR-S assay indicated a higher calcium mineral content deposition in cells of the experimental group. In conclusion, the ionic products of plasma-sprayed dicalcium silicate coating are beneficial to the proliferation and differentiation of MG63 osteoblast-like cells.