RESUMO
OBJECTIVE: Extracellular vesicles secreted by cardiosphere-derived cells (CDCev) polarize macrophages toward a distinctive phenotype with enhanced phagocytic capacity (MCDCev). These changes underlie cardioprotection by CDCev and by the parent CDCs, notably attenuating the no-reflow phenomenon following myocardial infarction, but the mechanisms are unclear. Here, we tested the hypothesis that MCDCev are especially effective at scavenging debris from dying cells (ie, efferocytosis) to attenuate irreversible damage post-myocardial infarction. Approach and Results: In vitro efferocytosis assays with bone marrow-derived macrophages, and in vivo transgenic rodent models of myocardial infarction, demonstrate enhanced apoptotic cell clearance with MCDCev. CDCev exposure induces sustained MerTK expression in MCDCev through extracellular vesicle transfer of microRNA-26a (via suppression of Adam17); the cardioprotective response is lost in animals deficient in MerTK. Single-cell RNA-sequencing revealed phagocytic pathway activation in MCDCev, with increased expression of complement factor C1qa, a phagocytosis facilitator. CONCLUSIONS: Together, these data demonstrate that extracellular vesicle modulation of MerTK and C1qa expression leads to enhanced macrophage efferocytosis and cardioprotection.
Assuntos
Proteína ADAM17/genética , Regulação da Expressão Gênica , Glicoproteínas de Membrana/genética , Infarto do Miocárdio/patologia , Fagocitose/genética , Receptores de Complemento/genética , c-Mer Tirosina Quinase/genética , Análise de Variância , Animais , Apoptose/genética , Biópsia por Agulha , Células Cultivadas , Modelos Animais de Doenças , Vesículas Extracelulares/metabolismo , Feminino , Humanos , Imuno-Histoquímica , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/genética , Ratos , Ratos Sprague-Dawley , Ratos Wistar , Receptores Proteína Tirosina Quinases/metabolismo , Análise de Sequência de RNARESUMO
BACKGROUND: Cardiosphere-derived cells (CDCs) confer cardioprotection in acute myocardial infarction by distinctive macrophage (MÏ) polarization. Here we demonstrate that CDC-secreted exosomes (CDCexo) recapitulate the cardioprotective effects of CDC therapy known as cellular postconditioning. METHODS: Rats and pigs underwent myocardial infarction induced by ischemia/reperfusion before intracoronary infusion of CDCexo, inert fibroblast exosomes (Fbexo; control), or vehicle. Two days later, infarct size was quantified. Macrophages were isolated from cardiac tissue or bone marrow for downstream analyses. RNA sequencing was used to determine exosome content and alterations in gene expression profiles in MÏ. RESULTS: Administration of CDCexo but not Fbexo after reperfusion reduces infarct size in rat and pig models of myocardial infarction. Furthermore, CDCexo reduce the number of CD68+ MÏ within infarcted tissue and modify the polarization state of MÏ so as to mimic that induced by CDCs. CDCexo are enriched in several miRNAs (including miR-146a, miR-181b, and miR-126) relative to Fbexo. Reverse pathway analysis of whole-transcriptome data from CDCexo-primed MÏ implicated miR-181b as a significant (P=1.3x10-21) candidate mediator of CDC-induced MÏ polarization, and PKCδ (protein kinase C δ) as a downstream target. Otherwise inert Fbexo loaded selectively with miR-181b alter MÏ phenotype and confer cardioprotective efficacy in a rat model of myocardial infarction. Adoptive transfer of PKCδ-suppressed MÏ recapitulates cardioprotection. CONCLUSIONS: Our data support the hypothesis that exosomal transfer of miR-181b from CDCs into MÏ reduces PKCδ transcript levels and underlies the cardioprotective effects of CDCs administered after reperfusion.
