BACKGROUND: This study, by regulating the expression level of microRNA-21 (miRNA-21) in antigen-1+ (Sca-1+) cardiac stem cells (CSCs), examined the role of miRNA-21 in migration, proliferation, and differentiation of Sca-1+ CSCs, and explored the use of miRNA-21 in treatment of heart-related diseases in mice.

MATERIAL AND METHODS: The CSCs of 20 healthy 2-month-old C57BL/6 mice were collected in our study. Immunomagnetic beads were used to separate and prepare pure Sca-1+ CSCs, which were further examined by flow cytometry. The samples were assigned to 4 groups: the blank group, the miRNA-21 mimic group, the miRNA-21 inhibitor group, and the negative control (NC) group. Quantitative real-time polymerase chain reaction (qRT-PCR), Transwell chamber assay, and the methyl thiazolylte-trazolium (MTT) assay were performed. Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to measure the expression levels of GATA-4, MEF2c, TNI, and β-MHC differentiation-related genes.

RESULTS: Immunomagnetic separation results indicated that Sca-1+ CSCs accounted for more than 87.4% of CSCs. RT-PCR results also showed that the expression level of miRNA-21 of the miRNA-21 mimic group was higher than those of the other groups (all P<0.05). Compared to the NC and the blank group, the migration of Sca-1+ CSCs was more active in the miRNA-21 mimic group and less active in the miRNA-21 inhibitor group (all P<0.05). Moreover, compared to the blank group, the proliferation of Sca-1+ CSCs was enhanced in the miRNA-21 mimic group and inhibited in the miRNA-21 inhibitor group (all P<0.05). The results of RT-PCR indicated that neither miRNA-21 mimics nor miR-21 inhibitors influenced the gene expression levels of GATA-4, MEF2c, TNI, or β-MHC.

CONCLUSIONS: Our study provides evidence that up-regulation of miRNA-21 can promote migration and proliferation of Sca-1+ CSCs to enhance the capacity of Sca-1+ CSCs to repair damaged myocardium, which may pave the way for therapeutic strategies directed toward restoring miRNA-21 function for heart-related diseases.

Keywords: Ataxin-1 - genetics, Cell Differentiation - genetics, MicroRNAs - genetics, Myocardium - metabolism, Stem Cells - physiology, Tumor Cells, Cultured