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Background: 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).Objectives: This study sought to test the hypothesis that ACCT synergistically promotes cardiac regeneration without provoking immunologic reactions.Methods: 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.Results: 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.Conclusions: 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. [ABSTRACT FROM AUTHOR]

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. Using xenogeneic (human) cells in immunosuppressed animals with acute ischemic heart disease, we previously showed that these 2 cell types act synergistically.Objectives: 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.Methods: 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.Results: Both groups of cell-treated animals exhibited significantly reduced scar size (MSCs -44.1 ± 6.8%; CSC/MSC -37.2 ± 5.4%; placebo -12.9 ± 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.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. [ABSTRACT FROM AUTHOR]