OBJECTIVETo observe the impact of mesenchymal stem cells (BMSCs) transplantation on myocardial myocardin-related transcription factor-A (MRTF-A) and bcl-2 expression in rats with experimental myocardial infarction (MI).

METHODSThirty rats were randomly divided into sham, MI and MI + BMSCs (1 × 10(6) injected into 4 infarct points immediately post coronary artery ligation) groups (n = 10 each).One week later, TUNEL was used to detect cardiomyocyte apoptosis, the myocardial expression of MRTF-A and bcl-2 was detected by laser scanning confocal microscope and Western blot. In vitro plasmid of MRTF-A and co-transfection with plasmids of MRTF-A and bcl-2 or mutated bcl-2 transfection into cardiomyocyte was applied to evaluate the relationship between MRTF-A and bcl-2.

RESULTSThe number of apoptotic cardiomyocytes in the sham group, MI group and MI + BMSCs group were (4.05 ± 1.56)%, (62.38 ± 8.41)% and (22.36 ± 6.17)%, respectively (P < 0.05). The protein expression of MRTF-A and bcl-2 in the MI group were significantly lower than those in sham group, while significantly upregulated in MI + BMSCs group (P < 0.05 vs. MI). In cultured neonatal rat cardiomyocyte, the expression of bcl-2 protein was significantly upregulated after transfection with MRTF-A plasmid, and bcl-2-luciferase activity significantly increased after co-transfection with plasmids of MRTF-A and bcl-2-luciferase, however, the positive regulatory effect of MRTF-A was abolished after transfection with mutated bcl-2.

CONCLUSIONMesenchymal stem cells transplantation can effectively reduce cardiomyocyte apoptosis in this rat MI model, and upregulate the expression of MRTF-A. Consequent up-regulated bcl-2 expression might be involved in the beneficial effects of BMSCs transplantation in this model.