Abstract
BackgroundPrevious studies have demonstrated that human cardiac c-Kit+ progenitor cells (hCPCs) can effectively improve ischemic heart disease. However, the major challenge in applying hCPCs to clinical therapy is the low survival rate of graft hCPCs in the host heart, which limited the benefit of transplanted hCPCs. Bradykinin (BK) is a principal active agent of the tissue kinin-kallikrein system. Our previous studies have highlighted that BK mediated the growth and migration of CPCs by regulating Ca2+ influx. However, the protective effect of BK on CPCs, improvement in the survival rate of BK-pretreated hCPCs in the infarcted heart, and the related mechanism remain elusive.MethodsHCPCs were treated with H2O2 to induce cell apoptosis and autophagy, and different concentration of BK was applied to rescue the H2O2-induced injury detected by MTT assay, TUNEL staining, flow cytometry, western blotting, and mitoSOX assays. The role of autophagy in the anti-apoptotic effect of BK was chemically activated or inhibited using the autophagy inducer, rapamycin, or the inhibitor, 3-methyladenine (3-MA). To explore the protective effect of BK on hCPCs, 3-MA or BK-pretreated hCPCs were transplanted into the myocardial infarcted rats. An echocardiogram was used to determine cardiac function, H&E and Masson staining were employed to assess pathological characteristics, HLA gene expression was quantified by qRT-PCR, and immunostaining was applied to examine neovascularization using confocal microscopy.ResultsThe in vitro results showed that BK suppressed H2O2-induced hCPCs apoptosis and ROS production in a concentration-dependent manner by promoting pAkt and Bcl-2 expression and reducing cleaved caspase 3 and Bax expression. Moreover, BK restrained the H2O2-induced cell autophagy by decreasing LC3II/I, Beclin1, and ATG5 expression and increasing P62 expression. In the in vivo experiment, the transplanted BK- or 3-MA-treated hCPCs were found to be more effectively improved cardiac function by decreasing cardiomyocyte apoptosis, inflammatory infiltration, and myocardial fibrosis, and promoting neovascularization in the infarcted heart, compared to untreated-hCPCs or c-kit- cardiomyocytes (CPC- cells).ConclusionsOur present study established a new method to rescue transplanted hCPCs in the infarcted cardiac area via regulating cell apoptosis and autophagy of hCPCs by pretreatment with BK, providing a new therapeutic option for heart failure.
Highlights
Previous studies have demonstrated that human cardiac c-Kit+ progenitor cells can effectively improve ischemic heart disease
Effects of BK on H2O2-induced human cardiac c-Kit+ progenitor cells (hCPCs) death and apoptosis We first explored whether BK had a protective effect on H2O2-induced hCPC death
A high amount of hCPC death was induced by H2O2 in a concentrationdependent manner, especially at 500 μM, and the cell viability decreased to approximately 70% (P < 0.01 vs. control) (Fig. 1A)
Summary
Previous studies have demonstrated that human cardiac c-Kit+ progenitor cells (hCPCs) can effectively improve ischemic heart disease. The protective effect of BK on CPCs, improvement in the survival rate of BK-pretreated hCPCs in the infarcted heart, and the related mechanism remain elusive. Cardiac c-Kit+ progenitor cell (CPC) therapy is a potentially novel approach to treat HF caused by ischemic cardiomyopathy [2]. Preclinical studies and clinical trials have demonstrated the potential of CPCs to alleviate chronic heart failure, the utmost potential of these cells has not been realized because of poor engraftment and survival. Exploring an effective strategy that enhances CPC survival rate after adoptive transfer would have enormous therapeutic implications for ischemic heart disease
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