Despite advances in stem cell biology, there are a few effective techniques to promote the bone regeneration in human bone defects after surgery in patient who suffer from osteosarcoma. One of the strategies for the regeneration of bone defects is “cell-based therapy”, using mesenchymal stem cells (MSCs). However, poor osteogenic differentiation of MSCs is an issue related to the application of these cells in “cell-based therapy”. Based on this fact, we were interested to investigate the ability of catechinconjugated hydroxyapatite (Cat@HAP) in the induction of osteogenic differentiation Osteogenic differentiation was verified by the evaluation of intracellular content of bone-related proteins, Runx2 and Osteocalcin (OCN), by flow cytometry. After 7 days of incubation of MSCs with Cat@HAP, the content of Runx2 significantly increased at the level of protein. Runx2 contains an active transactivation domain which activates the OCN gene [1]. The expression of down-stream signaling molecule, OCN, was also evaluated at the level of protein. OCN is involved in the bone mineralization and considered as a marker for the late stage of osteogenic differentiation [2]. According to the flow cytometry data, the expression level of OCN remarkably increased in MSCs cultured for 14 days with Cat@HAP. Based on these results, Cat@HAP could be considered as an appropriate candidate for the bone regeneration along with “cellbased therapy”.

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