Curcumin promote osteogenic differentiation of human bone marrow-derived MSCs through Ezh2- mediated histone modification

Mesenchymal Stem Cells (MSCs) are considered as a therapeutic target for cell-mediated regenerative medicine to treat human metabolic bone diseases. Numerous efforts have been made to promote efficient differentiation of MSCs into osteoblast lineage. Accordingly, epigenetic signatures emerge as a key conductor of cell differentiation. Enhancer of Zeste Homolog 2 (EZH2), a histone methyltransferase appeared to suppress osteogenesis. Curcumin is an osteoinductive natural polyphenol compound supposedly modulate epigenetic mechanisms. The current study aims to address the role of EZH2 epigenetic factor in osteogenic activity of human bone marrow-derived MSCs (hBMSCs) after treatment with curcumin. We isolated MSCs from aspirated bone marrow and characterized for differentiation to mesodermal lineages and cell surface markers. The optimum concentration of curcumin was achieved by MTT assay. The effects of curcumin on cellular behavior of viability and osteogenic differentiation were evaluated at different time points under in vitro condition. Moreover, the expression level of EZH2 was assessed using quantitative real-time polymerase chain reaction (qRT-PCR) after 14 and 21days. MTT results showed that curcumin at concentrations of 10 and 15 μM had no cytotoxic effect and cell survived up to 70%. qRT-PCR results demonstrated that curcumin significantly enhanced the expression level of osteogenic markers that include Runx2, osterix (Osx), collagen type I (ColI), osteopontin (OPN) and osteocalcin (OCN) at day 21. Interestingly, we observed that expression level of EZH2 gene downregulated in the presence of curcumin compared to control group during osteogenesis. It is proposed that curcumin act as an epigenetic switch to regulate osteoblast differentiation via decreasing histone methyltransferase EZH2.