hESC-Derived Epicardial Cells Promote Repair of Infarcted Hearts in Mouse and Swine.

Myocardial infarction (MI) causes excessive damage to the myocardium, including the epicardium. However, whether pluripotent stem cell-derived epicardial cells (EPs) can be a therapeutic approach for infarcted hearts remains unclear. Here, the authors report that intramyocardial injection of human embryonic stem cell-derived EPs (hEPs) at the acute phase of MI ameliorates functional worsening and scar formation in mouse hearts, concomitantly with enhanced cardiomyocyte survival, angiogenesis, and lymphangiogenesis. Mechanistically, hEPs suppress MI-induced infiltration and cytokine-release of inflammatory cells and promote reparative macrophage polarization. These effects are blocked by a type I interferon (IFN-I) receptor agonist RO8191. Moreover, intelectin 1 (ITLN1), abundantly secreted by hEPs, interacts with IFN-ß and mimics the effects of hEP-conditioned medium in suppression of IFN-ß-stimulated responses in macrophages and promotion of reparative macrophage polarization, whereas ITLN1 downregulation in hEPs cancels beneficial effects of hEPs in anti-inflammation, IFN-I response inhibition, and cardiac repair. Further, similar beneficial effects of hEPs are observed in a clinically relevant porcine model of reperfused MI, with no increases in the risk of hepatic, renal, and cardiac toxicity. Collectively, this study reveals hEPs as an inflammatory modulator in promoting infarct healing via a paracrine mechanism and provides a new therapeutic approach for infarcted hearts.

Dual human iPSC-derived cardiac lineage cell-seeding extracellular matrix patches promote regeneration and long-term repair of infarcted hearts.

Human pluripotent stem cell-derived cardiovascular progenitor cells (hCVPCs) and cardiomyocytes (hCMs) possess therapeutic potential for infarcted hearts; however, their efficacy needs to be enhanced. Here we tested the hypotheses that the combination of decellularized porcine small intestinal submucosal extracellular matrix (SIS-ECM) with hCVPCs, hCMs, or dual of them (Mix, 1:1) could provide better therapeutic effects than the SIS alone, and dual hCVPCs with hCMs would exert synergic effects in cardiac repair. The data showed that the SIS patch well supported the growth of hCVPCs and hCMs. Epicardially implanted SIS-hCVPC, SIS-hCM, or SIS-Mix patches at 7-day post-myocardial infarction significantly ameliorated functional worsening, ventricular dilation and scar formation at 28- and 90-day post-implantation in C57/B6 mice, whereas the SIS only mildly improved function at 90-day post-implantation. Moreover, the SIS and SIS-cell patches improved vascularization and suppressed MI-induced cardiomyocyte hypertrophy and expression of Col1 and Col3, but only the SIS-hCM and the SIS-Mix patches increased the ratio of collagen III/I fibers in the infarcted hearts. Further, the SIS-cell patches stimulated cardiomyocyte proliferation via paracrine action. Notably, the SIS-Mix had better improvements in cardiac function and structure, engraftments, and cardiomyocyte proliferation. Proteomic analysis showed distinct biological functions of exclusive proteins secreted from hCVPCs and hCMs, and more exclusive proteins secreted from co-cultivated hCVPCs and hCMs than mono-cells involving in various functional processes essential for infarct repair. These findings are the first to demonstrate the efficacy and mechanisms of mono- and dual-hCVPC- and hCM-seeding SIS-ECM for repair of infarcted hearts based on the side-by-side comparison.

Functional expression of the Ca2+ signaling machinery in human embryonic stem cells.

Emerging evidence suggests that Ca2+ signals are important for the self-renewal and differentiation of human embryonic stem cells (hESCs). However, little is known about the physiological and pharmacological properties of the Ca2+-handling machinery in hESCs. In this study we used RT-PCR and Western blotting to analyze the expression profiles of genes encoding Ca2+-handling proteins; we also used confocal Ca2+ imaging and pharmacological approaches to determine the contribution of the Ca2+-handling machinery to the regulation of Ca2+ signaling in hESCs. We revealed that hESCs expressed pluripotent markers and various Ca2+-handling-related genes. ATP-induced Ca2+ transients in almost all hESCs were inhibited by the inositol-1,4,5-triphosphate receptor (IP3R) blocker 2-APB or xestospongin C. In addition, Ca2+ transients were induced by a ryanodine receptor (RyR) activator, caffeine, in 10%-15% of hESCs and were blocked by ryanodine, whereas caffeine and ATP did not have additive effects. Moreover, store-operated Ca2+ entry (SOCE) but not voltage-operated Ca2+ channel-mediated Ca2+ entry was observed. Inhibition of sarco/endoplasmic reticulum (ER) Ca2+-ATPase (SERCA) by thapsigargin induced a significant increase in the cytosolic free Ca2+ concentration ([Ca2+]i). For the Ca2+ extrusion pathway, inhibition of plasma membrane Ca2+ pumps (PMCAs) by carboxyeosin induced a slow increase in [Ca2+]i, whereas the Na+/Ca2+ exchanger (NCX) inhibitor KBR7943 induced a rapid increase in [Ca2+]i. Taken together, increased [Ca2+]i is mainly mediated by Ca2+ release from intracellular stores via IP3Rs. In addition, RyRs function in a portion of hESCs, thus indicating heterogeneity of the Ca2+-signaling machinery in hESCs; maintenance of low [Ca2+]i is mediated by uptake of cytosolic Ca2+ into the ER via SERCA and extrusion of Ca2+ out of cells via NCX and PMCA in hESCs.