Cyclic mechanical strain promotes transforming-growth-factor-β1- mediated cardiomyogenic marker expression in bone-marrow-derived mesenchymal stem cells in vitro

Cardiomyocytes in the heart reside in mechanically dynamic environments, such as those subject to cyclic mechanical strain. TGF-β1 (transforming growth factor-β1) stimulates cardiomyogenic marker expression of BMMSCs (bone-marrow-derived mesenchymal stem cells). In the present study, we tested the hypothesis that cyclic mechanical strain promotes TGF-β1-mediated cardiomyogenic marker expression in BMMSCs in vitro. The mRNA expression of cardiac-specific genes was more up-regulated in BMMSCs cultured with a TGF-β1 supplement and subjected to cyclic strain for 1 week than in BMMSCs cultured statically with a TGF-β1 supplement. Immunocytochemical analyses and flow cytometric analysis showed that the proportions of cardiac troponin-I-positive cells and cardiac MHC (myosin heavy chain)-positive cells and the proportions of cells expressing tropomyosin respectively were increased to a greater extent by TGF-β1with cyclic strain than by TGF-β1 alone. These results showed that cyclic strain promotes TGF-β1-mediated cardiomyogenic marker expression in BMMSCs in vitro.