Rethinking Endothelial Dysfunction as a Crucial Target in Fighting Heart Failure

Endothelial dysfunction is characterized by nitric oxide dysregulation and an altered redox state. Oxidative stress and inflammatory markers prevail, thus promoting atherogenesis and hypertension, important risk factors for the development and progression of heart failure. There has been a reemerging interest in the role that endothelial dysfunction plays in the failing circulation. Accordingly, patients with heart failure are being clinically assessed for endothelial dysfunction via various methods, including flow-mediated vasodilation, peripheral arterial tonometry, quantification of circulating endothelial progenitor cells, and early and late endothelial progenitor cell outgrowth measurements. Although the mechanisms underlying endothelial dysfunction are intimately related to cardiovascular disease and heart failure, it remains unclear whether targeting endothelial dysfunction is a feasible strategy for ameliorating heart failure progression. This review focuses on the pathophysiology of endothelial dysfunction, the mechanisms linking endothelial dysfunction and heart failure, and the various diagnostic methods currently used to measure endothelial function, ultimately highlighting the therapeutic implications of targeting endothelial dysfunction for the treatment of heart failure

Route of Delivery Modulates the Efficacy of Mesenchymal Stem Cell Therapy for Myocardial Infarction

Accumulating data support a therapeutic role for mesenchymal stem cell (MSC) therapy; however, there is no consensus on the optimal route of delivery. We tested the hypothesis that the route of MSC delivery influences the reduction in infarct size and improvement in left ventricular ejection fraction (LVEF). We performed a meta-analysis investigating the effect of MSC therapy in acute myocardial infarction (AMI) and chronic ischemic cardiomyopathy preclinical studies (58 studies; n=1165 mouse, rat, swine) which revealed a reduction in infarct size and improvement of LVEF in all animal models. Route of delivery was analyzed in AMI swine studies and clinical trials (6 clinical trials; n=334 patients). In AMI swine studies, transendocardial stem cell injection reduced infarct size (n=49, 9.4% reduction; 95% confidence interval, -15.9 to -3.0), whereas direct intramyocardial injection, intravenous infusion, and intracoronary infusion indicated no improvement. Similarly, transendocardial stem cell injection improved LVEF (n=65, 9.1% increase; 95% confidence interval, 3.7 to 14.5), as did direct intramyocardial injection and intravenous infusion, whereas intracoronary infusion demonstrated no improvement. In humans, changes of LVEF paralleled these results, with transendocardial stem cell injection improving LVEF (n=46, 7.0% increase; 95% confidence interval, 2.7 to 11.3), as did intravenous infusion, but again intracoronary infusion demonstrating no improvement. MSC therapy improves cardiac function in animal models of both AMI and chronic ischemic cardiomyopathy. The route of delivery seems to play a role in modulating the efficacy of MSC therapy in AMI swine studies and clinical trials, suggesting the superiority of transendocardial stem cell injection because of its reduction in infarct size and improvement of LVEF, which has important implications for the design of future studies

Rethinking Endothelial Dysfunction as a Crucial Target in Fighting Heart Failure

Endothelial dysfunction is characterized by nitric oxide dysregulation and an altered redox state. Oxidative stress and inflammatory markers prevail, thus promoting atherogenesis and hypertension, important risk factors for the development and progression of heart failure. There has been a reemerging interest in the role that endothelial dysfunction plays in the failing circulation. Accordingly, patients with heart failure are being clinically assessed for endothelial dysfunction via various methods, including flow-mediated vasodilation, peripheral arterial tonometry, quantification of circulating endothelial progenitor cells, and early and late endothelial progenitor cell outgrowth measurements. Although the mechanisms underlying endothelial dysfunction are intimately related to cardiovascular disease and heart failure, it remains unclear whether targeting endothelial dysfunction is a feasible strategy for ameliorating heart failure progression. This review focuses on the pathophysiology of endothelial dysfunction, the mechanisms linking endothelial dysfunction and heart failure, and the various diagnostic methods currently used to measure endothelial function, ultimately highlighting the therapeutic implications of targeting endothelial dysfunction for the treatment of heart failure

ATTR Gene Variants in HCM

Hypertrophic cardiomyopathy is the most common inherited cardiomyopathy, with a prevalence of 1:200 to 1:500. Cardiac amyloidosis, another cardiomyopathy caused by myocardial deposition of abnormally folded TTR protein, can be acquired or hereditary. The presence of pathogenic TTR gene variants in patients with phenotypic HCM is an underrecognized and clinically important entity

Synergistic Effects of Combined Cell Therapy for Chronic Ischemic Cardiomyopathy

Both bone marrow–derived mesenchymal stem cells (MSCs) and c-kit+ cardiac stem cells (CSCs) improve left ventricular remodeling in porcine models and clinical trials. Using xenogeneic (human) cells in immunosuppressed animals with acute ischemic heart disease, we previously showed that these 2 cell types act synergistically. To more accurately model clinical applications for heart failure, this study tested whether the combination of autologous MSCs and CSCs produce greater improvement in cardiac performance than MSCs alone in a nonimmunosuppressed porcine model of chronic ischemic cardiomyopathy. Three months after ischemia/reperfusion injury, Göttingen swine received transendocardial injections with MSCs alone (n = 6) or in combination with cardiac-derived CSCs (n = 8), or placebo (vehicle; n = 6). Cardiac functional and anatomic parameters were assessed using cardiac magnetic resonance at baseline and before and after therapy. Both groups of cell-treated animals exhibited significantly reduced scar size (MSCs −44.1 ± 6.8%; CSC/MSC −37.2 ± 5.4%; placebo −12.9 ± 4.2%; p < 0.0001), increased viable tissue, and improved wall motion relative to placebo 3 months post-injection. Ejection fraction (EF) improved (MSCs 2.9 ± 1.6 EF units; CSC/MSC 6.9 ± 2.8 EF units; placebo 2.5 ± 1.6 EF units; p = 0.0009), as did stroke volume, cardiac output, and diastolic strain only in the combination-treated animals, which also exhibited increased cardiomyocyte mitotic activity. These findings illustrate that interactions between MSCs and CSCs enhance cardiac performance more than MSCs alone, establish the safety of autologous cell combination strategies, and support the development of second-generation cell therapeutic products

A Combination of Allogeneic Stem Cells Promotes Cardiac Regeneration

The combination of autologous mesenchymal stem cells (MSCs) and cardiac stem cells (CSCs) synergistically reduces scar size and improves cardiac function in ischemic cardiomyopathy. Whereas allogeneic (allo-)MSCs are immunoevasive, the capacity of CSCs to similarly elude the immune system remains controversial, potentially limiting the success of allogeneic cell combination therapy (ACCT). This study sought to test the hypothesis that ACCT synergistically promotes cardiac regeneration without provoking immunologic reactions. Göttingen swine with experimental ischemic cardiomyopathy were randomized to receive transendocardial injections of allo-MSCs + allo-CSCs (ACCT: 200 million MSCs/1 million CSCs, n = 7), 200 million allo-MSCs (n = 8), 1 million allo-CSCs (n = 4), or placebo (Plasma-Lyte A, n = 6). Swine were assessed by cardiac magnetic resonance imaging and pressure volume catheterization. Immune response was tested by histologic analyses. Both ACCT and allo-MSCs reduced scar size by -11.1 ± 4.8% (p = 0.012) and -9.5 ± 4.8% (p = 0.047), respectively. Only ACCT, but not MSCs or CSCs, prevented ongoing negative remodeling by offsetting increases in chamber volumes. Importantly, ACCT exerted the greatest effect on systolic function, improving the end-systolic pressure-volume relation (+0.98 ± 0.41 mm Hg/ml; p = 0.016). The ACCT group had more phospho-histone H3+ (a marker of mitosis) cardiomyocytes (p = 0.04), and noncardiomyocytes (p = 0.0002) than did the placebo group in some regions of the heart. Inflammatory sites in ACCT and MSC-treated swine contained immunotolerant CD3 /CD25 /FoxP3 regulatory T cells (p < 0.0001). Histologic analysis showed absent to low-grade inflammatory infiltrates without cardiomyocyte necrosis. ACCT demonstrates synergistic effects to enhance cardiac regeneration and left ventricular functional recovery in a swine model of chronic ischemic cardiomyopathy without adverse immunologic reaction. Clinical translation to humans is warranted

Synergistic Effects of Combined Cell Therapy for Chronic Ischemic Cardiomyopathy

BACKGROUND: Both bone marrow-derived mesenchymal stem cells (MSCs) and c-kit(+) cardiac stem cells (CSCs) improve left ventricular remodeling in porcine models and clinical trials. We previously showed, using xenogeneic (human) cells in immunosuppressed animals with acute ischemic heart disease, that these 2 cell types act synergistically in combination. OBJECTIVES: To more accurately model the clinical situation, we tested whether the combination of autologous MSCs and CSCs produced greater improvement of cardiac performance than MSCs alone in a nonimmunosuppressed porcine model of chronic ischemic cardiomyopathy. METHODS: Three months after ischemia/reperfusion infusion injury, Gottingen mini-swine were injected transendocardially with MSCs alone (n = 6) or in combination with cardiac-derived CSCs (n = 8), MSCs, or placebo (vehicle; n = 6). Cardiac functional and anatomic parameters were assessed by cardiac magnetic resonance at baseline and before and after therapy. RESULTS: Both groups of cell-treated animals exhibited significantly reduced scar size (MSCs: −44.1 ± 6.8%; CSC/MSC: −37.2 ± 5.4%; placebo: −12 ± 4.2%; p < 0.0001), increased viable tissue, and improved wall motion relative to placebo 3 months post-injection. Ejection fraction (EF) improved (MSCs: +2.9 ± 1.6; CSC/MSC: +6.9 ± 2.8; placebo: +2.5 ± 1.6 EF units; p = 0.0009), as did stroke volume, cardiac output, and diastolic strain, but only in the combination-treated animals, which also exhibited increased cardiomyocyte mitotic activity. CONCLUSIONS: These findings illustrate that interactions between MSCs and CSCs enhance cardiac performance more than MSCs alone, establish the safety of autologous cell combination strategies, and support the development of second-generation cell therapeutic products