Effect of biomimetic zinc-containing tricalcium phosphate (Zn-TCP) on the growth and osteogenic differentiation of mesenchymal stem cells.

Several studies have shown the effectiveness of zinc-tricalcium phosphate (Zn-TCP) for bone tissue engineering. In this study, marine calcareous foraminifera possessing uniform pore size distribution were hydrothermally converted to Zn-TCP. The ability of a scaffold to combine effectively with mesenchymal stem cells (MSCs) is a key tissue-engineering aim. In order to demonstrate the osteogenic ability of MSCs with Zn-TCP, the scaffolds were cultured in an osteogenic induction medium to elicit an osteoblastic response. The physicochemical properties of Zn-TCP were characterized by XRD, FT-IR and ICP-MS. MSCs were aspirated from rat femurs and cultured for 3 days before indirectly placing four samples into each respective well. After culture for 7, 10 and 14 days, osteoblastic differentiation was evaluated using alizarin red S stain, measurement of alkaline phosphatase (ALP) levels, cell numbers and cell viability. XRD and FT-IR patterns both showed the replacement of CO(3)(2-) with PO(4)(3-). Chemical analysis showed zinc incorporation of 5 mol%. Significant increases in cell numbers were observed at 10 and 14 days in the Zn-TCP group, while maintaining high levels of cell viability (> 90%). ALP activity in the Zn-TCP group was statistically higher at 10 days. Alizarin red S staining also showed significantly higher levels of calcium mineralization in Zn-TCP compared with the control groups. This study showed that MSCs in the presence of biomimetically derived Zn-TCP can accelerate their differentiation to osteoblasts and could potentially be useful as a scaffold for bone tissue engineering.