Abstract:

BACKGROUND: Bone marrow mesenchymal stem cells (BMSCs) have a lower survival rate after implanted into the ischemic myocardium. However, hypoxia precondition may enhance BMSCs proliferation and promote its survival rate.
OBJECTIVE: To stimulate the micro-environment of myocardial ischemia in vitro, and to investigate the protective effect of BMSCs on cardiomyocytes apoptosis continually induced by hypoxia after the hypoxia precondition (HP).
METHODS: The 4th passage SD rats BMSCs were used to prepare conditioned medium. Embryonic cardiomyocytes from rats were randomly divided into 4 groups: cardiomyocytes culture under normal condition alone (normal group), cardiomyocytes culture under hypoxia condition alone (model group), cardiomyocytes co-cultured with conditioned medium of BMSCs under normal condition (BMSCs group), cardiomyocytes co-cultured conditioned medium of BMSCs under hypoxia precondition (HP group). Changes in cell viability were measured by MTT assay, cardiomyocytes apoptosis was labeled by Annexin V-FITC/PI staining, and the protein expression of Bax and Bcl-2 were detected by immunohistochemisty staining in each group.
RESULTS AND CONCLUSION: The immunohistochemisty demonstrated that Bcl-2 expression in HP group was increased (P < 0.05), compared with control group, model group, and BMSCs group; While, compared with model group and BMSCs group, Bax expression in HP group was reduced, and the ratio of Bcl-2/Bax is maximum. Compared with control group and BMSCs group, cell viability in HP group was increased (P < 0.05), the apoptosis rate was reduced (P < 0.05). It suggested that HP may regulate Bax and Bcl-2 through the enhancement of paracrine mechanism, and which has a protective effect on cardiomyocytes apoptosis.