Anti-adipogenic effects of sesamol on human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) from adult bone marrow are able to differentiate into adipocytes, osteoblasts, chondrocytes and neuronal cells. Adipocytes in bone marrow are primarily responsible for the maintenance of bone structure by maintaining cell number balance with other stromal cells. However, the number of adipocytes in the bone marrow increases with age, leading to an imbalance of the bone marrow microenvironment, which results in a disruption of bone structure. In addition, the excessive number of adipocytes in bone marrow can cause diseases, such as osteoporosis or anemia. In this study, we investigated the effect of sesamol, a major natural phenolic compound of sesame oil, on the adipogenic differentiation of hMSCs. Numerous studies have reported the anti-oxidant property of sesamol, but its effect on cell differentiation has not yet been shown. We first found that sesamol treatment during adipogenic differentiation of hMSCs reduced intracellular lipid accumulation, which was unrelated to lipolysis. Interestingly, sesamol diminished the expression of genes responsible for adipogenesis, but increased the expression of osteogenic genes. In addition, sesamol decreased the expression of genes necessary for adipocyte maturation without affecting the expression of hMSC-specific genes. Studies concerning intracellular signaling in hMSCs showed that the extracellular signal-regulated kinase 1/2 (ERK1/2) was decreased by sesamol, which was similar with the effect of an ERK1/2 inhibitor. Overall, this study demonstrates that sesamol can attenuate the adipogenic differentiation of hMSCs without affecting its characteristics through the inhibition of ERK1/2 pathway. Herein, this study reports for the first time the effect of sesamol on hMSC differentiation and suggests the possibility of using sesamol as a therapeutic agent to treat intraosseous disruption triggered by the excessive adipogenesis of hMSCs.