HIF-1α modulates β-catenin pathway to enhance the survival and angiogenesis of PBMSCs under hypoxia environment

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.