Background: Efficacy of intravenous mesenchymal stem cells (MSCs) administration for myocardial infarction (MI) is limited by low cell migration to the damaged myocardium. Our previous study demostrated that migration ability of MSCs enhanced by hypoxia preconditioning (HPC). miRNA microarray displayed that miR-211 exhibited most significant change between HPC and normoxia cultured MSCs. The aim of this study is to study whether and how miR-211 regulate MSCs migration.
Methods: In vitro, transwell assay were used to assess the migration ability of MSC moduated by miR-211 using overexpressing and knockdown lentivirus. The target gene of miR-211 predicted by Targetscan were verified by PCR, western blot and lucifurase assay. Chromatin immunoprecitation (ChiP) were used to explore the transcription factors that regulate the expression of miR-211. To evaluate the effect of miR-211 on MSCs migration in vivo, miR-211-mimic and miR-211-shRNA male MSCs were intravenously delivered 24h after MI, the engraft cells were detected by RT-PCR of SRY gene.
Results: Quatitative RT-PCR showed that miR-211 expression of MSCs upregulated by HPC. MiR-211 mimic improved MSCs migration by 31.03% (p<0.05), however, knockdown miR-211 using shRNA attenuated MSCs migration ability significantly. Signal transducer and activator of transcription 5A (STAT5A) was predicted as one of miR-211 target genes, PCR and Western blot showed miR-211 overexpression dramatically decreased STAT5A expression, while miR-211 knockdown upregulated STAT5A. The luciferase assay showed the similar results. Transwell assay showed that STAT5A knockdown reverse the inhibition of MSCs migration induced by miR-211-shRNA. Intrestingly, ChiP assay showed that STAT5A can combine to the promoter of miR-211, which lead to the regulation of miR-211 transcription. In vivo data showed that MiR-211 overexpression enhanced MSCs homing to ischemic myocardium, and miR-211 overexprssing MSCs improved cardiac function 28days post-MI. However, miR-211 knockdown decreased MSCs homing and hampered cardiac function recovery.
Conclusions: These results indicate that miR-211 has important role in regulating MSCs migration through targeting STAT5A, meanwhile STAT5A regulated miR-211 transcription.