Bone marrow-derived mesenchymal stem cells (BMSCs) are multipotent stem cells that differentiate into a variety of cell types and widely used in tissue regeneration engineering. The purpose of this study is to investigate whether the cyclic biaxial stretching strain could promote the rat BMSCs (rBMSCs) to differentiate into cardiomyocyte-like cells in vitro. The second or third generation of rBMSCs were randomly divided into the cyclic stretching stain group, the control group and the blank group. Those rBMSCs in the cyclic stretching strain group were seeded on a silicone membrane with complete medium were exposed to biaxial stretching strain of 10% of membrane at a frequency of 1 Hz lasting for 6 h, 12 h and 24 h. Those in the control group were seeded on silicone membrane with complete medium. Those in the blank group were seeded in the 6-wells plates with complete medium. The mRNA expression of GATA4 and myocyte-specific enhancer factor 2C (MEF-2C) were detected by the real-time fluorescent quantification PCR and the protein expression of connexin 43 (Cx43) was detected by using the Western blot method. The results showed that the mRNA expression level of the GATA4 and MEF-2C, and the protein expression level of Cx43 were significantly higher in the cyclic stretching strain groups, compared with those in the relative control groups (P<0.05). It suggests that cyclic biaxial stretching strain could play a part in the induction of rBMSCs to differentiate into cardiomyocyte-like cells in vitro, but the differentiation mechanism is still unclear.
Bone marrow-derived mesenchymal stem cells (BMSCs) for repairing damaged heart tissue are a new kind of important treatment options because of their potential to differentiate into cardiomyocytes. We in this experiment investigated the effect of different electrical stimulation time on the expression of myocardial specificity gene and protein in rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. The rBMSCs of second or third generation were randomly divided into three groups, i.e. electrical stimulation (ES) group, 5-Azacytidine (5-Aza) group and the control group. The rBMSCs in the ES groups with complete medium were exposed to 2 V, 2 Hz, 5 ms electrical stimulation for 0.5 h, 2 h, 4 h, and 6 h respectively every day for 10 days. Those in the 5-Aza group were induced by 5-Aza (10 μmol/L) for 24 h, and then cultured with complete medium for 10 days. Those in the control group were only cultured with complete medium, without any treatment, for 10 days. The rBMSCs' morphological feature in each group was observed with inverted phase microscope. The mRNA expression of myocyte-specific enhancer factor 2C (MEF-2C) and connexin 43 (Cx43) were examined with Real-Time quantitative PCR and the protein expression of MEF-2C, Cx43 were detected with Western Blot method. The results showed that the mRNA expression level of the MEF-2C, Cx43 and the protein expression level of MEF-2C, Cx43 were significantly higher in the ES group and 5-Aza group than those in the relative control group (P < 0.05). It suggests that electrical stimulation could play a part of role in the induction of the rBMSCs to differentiate into the cariomyocyte-like cells in vitro and the effectiveness of the electrical stimulation with 2 h/d had the best in our experiement. But the mechanism how electrical stimulation promotes the differentiation of rBMSC into cardiomyocyte is still unclear.