[Effect and related mechanism of miRNA-21 on hydrogen peroxide-induced C-kit(+) cardiac stem cells apoptosis].

Objective To explored the effect and related mechanism of miRNA-21 on hydrogen peroxide-induced C-kit+ cardiac stem cells apoptosis. Methods C-kit+ cardiac stem cells were isolated from SD rats by the methods of enzyme digestion and magnetic bead. Cells were divided into the following experimental groups: (1) negative control mimics (NCM)group: cells were transfected with negative control miRNA-21 mimics for 48 hours; (2)mimics group: cells were transfected with miRNA-21 mimics for 48 hours; (3) NCM+ H2O2 group: negative control miRNA-21 mimics were transfected into cells for 48 hours and then treated with 100 μmol H2O2 for 2 hours; (4)mimics+ H2O2 group: miRNA-21 mimics were transfected into cells for 48 hours and then treated with 100 μmol H2O2 for 2 hours. mRNA of miRNA-21 was detected by RT-PCR. The apoptosis rate of C-kit+ cardiac stem cells was determined using the annexin V-FITC/PI staining assay. Western blot was employed to measure the expression of apoptosis related proteins(Caspase-3, Bax, and Bcl-2). Results (1) Compared with the NCM group, the mRNA expression level of miRNA-21 was significantly up-regulated in mimics group, while obviously down-regulated in NCM+ H2O2 group(all P 0.05). Compared with the NCM group, the early apoptosis rates were remarkably increased ((79.07±5.75)% vs.(4.57±3.45)%, P 0.05). Compared with the NCM group, the Caspase-3 and Bax protein expression was significantly increased in NCM+ H2O2 group (all P 0.05). The Caspase-3 and Bax protein expression was markedly decreased, while Bcl-2 apparently increased in the mimics+ H2O2 group compared with the NCM+ H2O2 group(all P<0.05). Conclusion Overexpression of miRNA-21 protects the C-kit+ cardiac stem cells from apoptosis caused by oxidative stress through downregulating proapoptotic and upregulating the antiapoptotic proteins. Key words: Stem cells; Apoptosis; Oxidative stress