Osteogenic differentiation of osteoblasts induced by calcium silicate and calcium silicate/β-tricalcium phosphate composite bioceramics

In this study, calcium silicate (CS) and CS/beta-tricalcium phosphate (CS/beta-TCP) composites were investigated on their mechanism of osteogenic proliferation and differentiation through regulating osteogenic-related gene and proteins. Osteoblast-like cells were cultured in the extracts of these CS-based bioceramics and pure beta-TCP, respectively. The main ionic content in extracts was analyzed by inductively coupled plasma-atomic emission spectroscopy. The cell viability, mineralization, and differentiation were evaluated by MTT assay, Alizarin Red-S staining and alkaline phosphatase (ALP) activity assay. The expressions of BMP-2, transforming growth factor-beta (TGF-beta), Runx2, ALP, and osteocalcin (OCN) at both gene and protein level were detected by real-time polymerase chain reaction analysis and Western blot. The result showed that the extracts of CS-based bioceramics promoted cells proliferation, differentiation, and mineralization when compared with pure beta-TCP. Accordingly, pure CS and CS/beta-TCP composites stimulated osteoblast-like cells to express BMP-2/TGF-beta gene and proteins, and further regulate the expression of Runx2 gene and protein, and ultimately affect the ALP activity and OCN deposition. This study suggested that the CS-based bioceramics could not only promote the expression of osteogenic-related genes but also enhance the genes to encode the corresponding proteins, which could finally control osteoblast-like cells proliferation and differentiation. (c) 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.