Curcumin increases rat mesenchymal stem cell osteoblast differentiation but inhibits adipocyte differentiation

Background: Curcumin is a phenolic natural product isolated from the rhizome of Curcuma longa (turmeric) and has effects on bone health and fat formation. The bone marrow mesenchymal stem cells (MSCs) are multipotent cells capable of differentiating into osteoblasts and adipocytes. Osteoblast differentiation of MSCs can be a result of upregulation of heme oxygenase (HO)-1 expression. Curcumin can potently induce HO-1 expression. Objective: The present study describes the effects of curcumin on rat MSC (rMSCs) differentiation into osteoblasts and adipocytes. Materials and Methods: Rat bone marrow MSCs were isolated and treated with or without curcumin. Osteoblast differentiation was confirmed and determined by alkaline phosphatase (ALP) activity, mineralized nodule formation, the expression of Runx2 (runt-related transcription factor 2) and osteocalcin. Adipocyte differentiation was determined by Oil red O staining and the expression of peroxisome proliferator-activated receptor-γ 2 (PPARγ2) and CCAAT/enhancer- binding protein (C/EBP) α. Results: Curcumin increased ALP activity and osteoblast-specific mRNA expression of Runx2 and osteocalcin when rMSCs were cultured in osteogenic medium. In contrast, curcumin decreased adipocyte differentiation and inhibited adipocyte-specific mRNA expression of PPARγ2 and C/EBPα when rMSCs were cultured in adipogenic medium. HO-1 expression was increased during osteogenic differentiation of rMSCs. Conclusions: These findings demonstrate that curcumin can promote osteogenic differentiation of rMSCs and inhibit adipocyte formation. The effect of curcumin on osteogenic differentiation of rMSCs is correlated with HO-1 expression.