Abstract:
Background: Human induced pluripotent stem cell–derived endothelial cells (hiPSC-ECs) exhibit potential in repairing the injured heart after myocardial infarction (MI) by promoting neovascularization and cardiomyocyte survival. However, because of the low cellular retention and poor engraftment efficacy, cell therapy treatment of MI is in part mediated by exosomes secreted from the transplanted cells. We investigated whether exosomes secreted from hiPSC-ECs could become a promising acellular approach to repairing the infarcted heart after MI, and elucidated the underlying protective mechanism.
Methods: hiPSC-ECs were differentiated and exosomes were isolated in vitro. Then, hiPSC-EC exosomes were delivered by intramyocardial injection in a murine MI model in vivo. Echocardiography, combined with hemodynamic measurement, histological examination, Ca2+ transient and cell shortening assessment, and western blot, was used to determine protective effects of hiPSC-EC exosomes on the infarcted heart. Furthermore, microRNA sequencing, luciferase activity assay, and microRNA gain–loss function experiments were performed to investigate the enriched microRNA and its role in exosome-mediated effects.
Results: In vitro assessments demonstrated that hiPSC-EC exosomes could be taken up by cardiomyocytes and that they possess the capability to protect cardiomyocytes from oxygen–glucose deprivation injury by enhancing Ca2+ transients, increasing ATP content, and promoting cell survival. Congruously, hiPSC-EC exosomes administration in vivo not only improved myocardial contractile function but also attenuated the harmful left ventricular remodeling after MI. Mechanistically, hiPSC-EC exosomes notably rescued the protein expression and function of sarcoplasmic reticulum Ca2+ ATPase 2a (SERCA-2a) and ryanodine receptor 2 (RyR-2) to maintain intracellular Ca2+ homeostasis and increase cardiomyocyte contraction after MI. microRNA sequencing determined that miR-100-5p was the most abundant microRNA in exosomes, and miR-100-5p could target protein phosphatase 1β (PP-1β) to enhance the phosphorylation level of phospholamban (PLB) at Ser16 and subsequent SERCA activity, which contributes to the hiPSC-EC exosome–exerted cytoprotective effects on maintaining intracellular Ca2+ homeostasis and promoting cardiomyocyte survival.
Conclusion: hiPSC-EC exosomes maintain cardiomyocyte Ca2+ homeostasis to improve myocardial recovery after MI, which may provide an acellular therapeutic option for myocardial injury. Keywords: hiPSC-ECs, exosomes, Ca2+ homeostasis, miR-100-5p
Journal Link: Research Square Other Link: Download PDF Other Link: Google Scholar
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