Abstract
BACKGROUND: Stem cell therapy has been recognized as a promising strategy for enhancing cardiac function after myocardial infarction. Nonetheless, its clinical benefits are frequently limited by the poor survival and differentiation rates of the transplanted cells. AIM: To clarify the role of hypoxia-inducible factor-1α (HIF-1α)/β-catenin in survival and angiogenesis of peripheral blood mesenchymal stem cells (PBMSCs). METHODS: PBMSCs were isolated from rat abdominal aorta blood and characterized by multipotent differentiation assays. Cells were cultured under hypoxic conditions, followed by either overexpression or silencing of HIF-1α/β-catenin. Proliferative capacity was evaluated via colony formation assays, while cellular senescence was assessed using β-galactosidase staining. The protein and/or mRNA expressions of HIF-1α, β-catenin, basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), survivin, Bcl2, Bax, cleaved caspase 3 were detected via western blotting and/or quantitative real-time polymerase chain reaction. PBMSCs co-expressing elevated HIF-1α and β-catenin levels were transplanted into infarcted myocardial tissue to evaluate their therapeutic potential in vivo. RESULTS: HIF-1α or β-catenin overexpression enhanced self-renewal and inhibit apoptosis of PBMSCs by up-regulating Bcl2 and survivin, down-regulating Bax and cleaved-caspase 3. Besides, HIF-1α or β-catenin overexpression elevated angiogenesis via increasing bFGF and VEGF expressions. Silence of HIF-1α or β-catenin had opposite effect. Upregulation of HIF-1α increased β-catenin expression, whereas modifications in β-catenin did not influence HIF-1α expression. Chromatin immunoprecipitation assay verified that HIF-1α directly modulates β-catenin transcription. In vivo, HIF-1α overexpression significantly improved the retention of transplanted PBMSCs in infarcted myocardium and enhanced myocardial repair. Functional analysis further confirmed that HIF-1α operated through β-catenin, which directly modulated the expression of bFGF, VEGF, survivin, Bcl2, Bax and cleaved caspase 3, thereby coordinating the anti-apoptotic and pro-angiogenic functions of transplanted PBMSCs. CONCLUSION: This study highlights the modulatory function of HIF-1α on PBMSCs via β-catenin-driven anti-apoptotic and angiogenic signaling cascade under hypoxia environment, offering a promising strategy for improving the therapeutic effectiveness PBMSCs-based transplantation after myocardial infarction.