Original Article The effect of synthetic α-tricalcium phosphate on osteogenic differentiation of rat bone mesenchymal stem cells

The reconstruction of large bone defects has been the focus in bone tissue engineering research. By acting as synthetic frameworks for cell growth and tissue formation, biomaterials can play a critical role in bone tissue engineering. Among various biomaterials, calcium phosphate based materials include hydroxyapatite (HA), α-tricalcium phosphate (α-TCP), and β-tricalcium phosphate (β-TCP) are widely used as scaffold materials in bone tissue engineering. However, little is known about the effect of α-TCP alone on the osteogenic differentiation of the BMSCs. To this end, we synthesized α-TCP using a novel co-precipitation method. The synthetic α-TCP was then incubated with rat BMSCs under osteogenic inductive medium culture conditions, followed by the analysis of the mRNA levels of various osteogenesis-related genes, including ALP, Rux2, COL-I, and SP7, using a quantitative RT- PCR method. Following incubation of BMSCs with 20 μg/ml α-TCP, cells reached confluency after 7 days. Addition - ally, the MTT analysis showed that α-TCP at concentration of 10-20 μg/ml had good biocompatibility with BMSCs, showing no significant inhibition of rat BMSCs proliferation. Furthermore, the synthetic α-TCP (20 μg/ml), when incubated with rat BMSCs in the osteogenic culture medium, increased the mRNA levels of various osteogenesis- related genes, including ALP, Rux2, COL-I, and SP7. Finally, treatment of synthetic α-TCP (20 μg/ml) potentiated calcium nodule formations after incubation with rat BMSCs in osteogenic culture medium for 21 days, as compared with non-treated control. Taken together, the results in the present study suggested that α-TCP alone likely promotes rat BMSCs osteogenic differentiation through up-regulating ALP, Col-I, Runx2, and SP7 gene expression.