Objective: To investigate the effect of cardiac transplanting of mesenchymal stem cells on the apoptosis after rat myocardial infarction.
Methods: Wistar inbred rats were used to stimulate autograft. Harvested rat mesenchymal stem cells were cultivated, proliferated and labeled in vitro. At the same time, myocardial infarct models were set up using liquid nitrogen to cryoinjury the free wall of the left ventricule. Four weeks later, 2 x 10(6) mesenchymal stem cells or cold D-Hanks liquid were injected into several different points of infarct area. After 1, 2 and 4 weeks, specimens from infarct area were obtained in order. Then the number of apoptosis was counted under scanning electron microscope in every 2 specimens selected at random from the experimental group and the reference group within 2 weeks. The bcl-2 mRNA expression of all rats was assayed by RT-PCR.
Results: The observation of transmission by electron microscope showed that part of the myocardial cells became apoptosis in the initial stage in ultramicrostructure. Apoptosis ratio was 0.02 and 0.08 in the experimental group and the reference group respectively, which demonstrated that mesenchymal stem cells could relieve apoptosis after rat myocardial infarctation. The levels of bcl-2 mRNA expression in 1, 2, and 4 weeks were all obviously promoted in the experimental 1.2. group (3.235 +/- 0.126, 1.152 +/- 0.021, 0.798 +/- 0.016) than those in the reference group (2. 695 +/- 0.084, 0.537+/-0.022, 0.579+/-0.019) (P < 0.01), and quickly decreased with time.
Conclusion: Mesenchymal stem cells transplantation can promote the expression of bcl-2 mRNA in the infarct area and relieve apoptosis after rat myocardial infarction.