Abstract: Objective To investgate the effect of miR-1 on MSCs differentiation into cardiac phenotypes and the expression changes of Notch signaling molecules in this process.Methods MSCs were isolated from rat bone marrow by the whole bone marrow adherence method; MSCs identified by flow cytometry were introduced by the lentiviral vectors expressing miR-1（MSCsmiR-1）,Which were then divided into four groups: control group, 4-day culture group, 6-day culture group,15-day culture group;The cell morphology was examied by light microscope,miR-1 and cardiomyocyte-specific genes including GATA-4, cTnI and α-actin were examined by real-time quantitative polymerase chain reaction (qPCR),and the expression of cTnI and α-actin was detected by immunofluorescence and Western blot respectively;Meanwhile, MSCsmiR-1 cells were detected for the expression of genes related to notch signaling pathway by qPCR. Results Isolated MSCs displayed a stable spindle-phenotype and showed characteristic swirling growth. More than 98% of the MSCs population expressed CD44 and CD29 for MSCs phenotype; Meanwhile, less than 1% cells were CD45 positive. Compared with control cells, MSCsmiR-1 highly expressed miR-1 and showed a higher expression of cardiomyocyte-specific genes, including GATA-4, cTnI and α-actin, cTnI was detected by immunofluorescence in MSCsmiR-1 after miR-1 transduction for 4 days, and gradually increased afterwards. Western blot further confirmed the expression of α-actin in MSCsmiR-1. The mRNA expression of Jagged1,Notch1,Notch3 and Hey2 reduced significantly in MSCsmiR-1 during its differentiation into cardiomyocyte-like cells,and reached the minimum on day 15. Conclusions Our study suggests that transduction of miR-1 into rat MSCs induce cell differentiation into cardiomyocyte-like cells,which is in company with down-regulation mRNA expression of Jagged1- Notch1/ Notch3-Hey2 in the Notch pathway.

Key words: miR-1, MSCs, cardiomyocyte-specific cells, differentiation, notch