Macrophages mediate cardioprotective cellular postconditioning in acute myocardial infarction
Geoffrey de Couto, … , Moshe Arditi, Eduardo Marbán
Geoffrey de Couto, … , Moshe Arditi, Eduardo Marbán
Published July 27, 2015
Citation Information: J Clin Invest. 2015;125(8):3147-3162. https://doi.org/10.1172/JCI81321.
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Research Article Cardiology

Macrophages mediate cardioprotective cellular postconditioning in acute myocardial infarction

Abstract

Ischemic injury in the heart induces an inflammatory cascade that both repairs damage and exacerbates scar tissue formation. Cardiosphere-derived cells (CDCs) are a stem-like population that is derived ex vivo from cardiac biopsies; they confer both cardioprotection and regeneration in acute myocardial infarction (MI). While the regenerative effects of CDCs in chronic settings have been studied extensively, little is known about how CDCs confer the cardioprotective process known as cellular postconditioning. Here, we used an in vivo rat model of ischemia/reperfusion (IR) injury–induced MI and in vitro coculture assays to investigate how CDCs protect stressed cardiomyocytes. Compared with control animals, animals that received CDCs 20 minutes after IR had reduced infarct size when measured at 48 hours. CDCs modified the myocardial leukocyte population after ischemic injury. Specifically, introduction of CDCs reduced the number of CD68+ macrophages, and these CDCs secreted factors that polarized macrophages toward a distinctive cardioprotective phenotype that was not M1 or M2. Systemic depletion of macrophages with clodronate abolished CDC-mediated cardioprotection. Using both in vitro coculture assays and a rat model of adoptive transfer after IR, we determined that CDC-conditioned macrophages attenuated cardiomyocyte apoptosis and reduced infarct size, thereby recapitulating the beneficial effects of CDC therapy. Together, our data indicate that CDCs limit acute injury by polarizing an effector macrophage population within the heart.

Authors

Geoffrey de Couto, Weixin Liu, Eleni Tseliou, Baiming Sun, Nupur Makkar, Hideaki Kanazawa, Moshe Arditi, Eduardo Marbán

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Figure 9

Coculture of MCDC macrophages with oxidatively stressed NRVMs preserves cardiomyocyte viability in vitro.

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Coculture of MCDC macrophages with oxidatively stressed NRVMs preserves ...
(A) Schematic of in vitro protocol. NRVMs were stressed with 50 μM H2O2 for 15 minutes, serum-free media was replaced for 20 minutes (to simulate reperfusion), and then DiO-labeled M1, M2, or MCDC macrophages were introduced to the NRVMs. After 6 hours, cells were collected for analyses (n = 3 per group). (B) Immunoblot of cocultured cells (M1, M2, or MCDC macrophages with H2O2-treated NRVMs) and NRVM positive and negative controls (with and without H2O2, respectively) after 6 hours of culture. The lanes for this blot were run on the same gel but were noncontiguous. (C) Representative images of TUNEL-stained (red) cocultures of M1, M2, or MCDC macrophages (green) with NRVMs (white). Scale bar: 50 μm. (D) Pooled quantitative analyses of TUNEL+ cardiomyocytes (CM) and viable nucleated cardiomyocytes from M1, M2, and MCDC cocultures. (E) Pooled data demonstrating increased macrophage numbers in M1 cocultures and increased TUNEL+ macrophages in M2 cocultures. Graphs depict mean ± SEM. Statistical significance was determined using 1-way ANOVA followed by Tukey’s multiple comparisons test. *P < 0.05.