Ischaemia/reperfusion induced cardiac stem cell homing to the injured myocardium by stimulating stem cell factor expression via NF-κB pathway

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Ischaemia/reperfusion (I/R) is a major cause of heart failure. Recently cardiac stem cells (CSCs) were proposed as the most appropriate cell type for heart disease therapy. However, it is still unclear whether I/R can stimulate the CSCs homing to the injured myocardium. Male Sprague–Dawley rats were subjected to a 30-min ischaemia followed by reperfusion of different intervals. RT-PCR, western blotting and immunohistochemistry were performed to detect stem cell factor (SCF) expression at mRNA and protein levels respectively. Activation of nuclear factor-κB (NF-κB) was determined by electrophoretic mobility shift assay. To assess the homing of CSCs in vivo, BrdU-labelled CSCs were injected into AV-groove before induction of ischaemia and examined by immunofluorescent staining in the injured myocardium after I/R. From day 3 to day 6 after reperfusion, the accumulation of CSCs was significantly elevated in the injured area, which was matched with the increased SCF expression during I/R. Pretreatment of rats with NF-κB inhibitor, N-acetyl-l-cysteine (NAC) not only suppressed NF-κB activation induced by I/R but also attenuated SCF expression. Further analysis revealed that I/R induced phosphorylation of IκBα after 15 min of reperfusion, and the raised phosphor-IκBα returned to the basal level at 2 h of reperfusion. In simulated I/R(SI/R) in vitro, it enhanced NF-κB activation and SCF expression in cultured neonatal rat cardiomyocytes, which was markedly inhibited by NF-κB decoy oligodeoxynucleotide or NAC. Taken together, our results demonstrated that I/R induced CSCs homing to the injured myocardium by stimulating myocardial SCF expression via activation of NF-κB.

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