RESUMO
AIM: Cell therapies are hampered by poor survival and growth of grafts. We tested whether forced co-expression of telomerase reverse transcriptase (TERT) and myocardin (MYOCD) improves post-infarct revascularization and tissue repair by adipose tissue-derived mesenchymal stromal cells (AT-MSCs). METHODS AND RESULTS: We transplanted AT-MSCs overexpressing MYOCD and TERT in a murine model of acute myocardial infarction (AMI). We characterized paracrine effects of AT-MSCs. When transplanted into infarcted hearts of C57BL/6 mice, AT-MSCs overexpressing TERT and MYOCD decreased scar tissue and the intra-scar CD3 and B220 lymphocyte infiltration; and increased arteriolar density as well as ejection fraction compared with saline or mock-transduced AT-MSCs. These effects were accompanied by higher persistence of the injected cells in the heart, increased numbers of Ki-67+ and CD117+ cells, and the expression of cardiac actin and ß-myosin heavy chain. Intramyocardial delivery of the secretome and its extracellular vesicle (EV)-enriched fraction also decreased scar tissue formation and increased arteriolar density in the murine AMI model. Proteomic analysis of AT-MSCs-EV-enriched fraction predicted the activation of vascular development and the inhibition of immune cell trafficking. Elevated concentrations of miR-320a, miR-150-5p and miR-126-3p associated with regulation of apoptosis and vasculogenesis were confirmed in the AT-MSCs-EV-enriched fraction. CONCLUSIONS: AT-MSCs overexpressing TERT and MYOCD promote persistence of transplanted aged AT-MSCs and enhance arteriolar density in a murine model of AMI. EV-enriched fraction is the component of the paracrine secretion by AT-MSCs with pro-angiogenic and anti-fibrotic activities.
Assuntos
Transplante de Células-Tronco Mesenquimais , Células-Tronco Mesenquimais/enzimologia , Infarto do Miocárdio/cirurgia , Miocárdio/metabolismo , Proteínas Nucleares/metabolismo , Regeneração , Telomerase/metabolismo , Transativadores/metabolismo , Proteínas Angiogênicas/genética , Proteínas Angiogênicas/metabolismo , Animais , Células Cultivadas , Modelos Animais de Doenças , Vesículas Extracelulares/enzimologia , Vesículas Extracelulares/transplante , Fibrose , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , MicroRNAs/genética , MicroRNAs/metabolismo , Infarto do Miocárdio/enzimologia , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Miocárdio/patologia , Proteínas Nucleares/genética , Comunicação Parácrina , Recuperação de Função Fisiológica , Transdução de Sinais , Telomerase/genética , Transativadores/genéticaRESUMO
Cardioprotection against ischemia/reperfusion injury is still an unmet clinical need. The transient activation of Toll-like receptors (TLRs) has been implicated in cardioprotection, which may be achieved by treatment with blood-derived extracellular vesicles (EVs). However, since the isolation of EVs from blood takes considerable effort, the aim of our study was to establish a cellular model from which cardioprotective EVs can be isolated in a well-reproducible manner. EV release was induced in HEK293 cells with calcium ionophore A23187. EVs were characterized and cytoprotection was assessed in H9c2 and AC16 cell lines. Cardioprotection afforded by EVs and its mechanism were investigated after 16 h simulated ischemia and 2 h reperfusion. The induction of HEK293 cells by calcium ionophore resulted in the release of heterogenous populations of EVs. In H9c2 and AC16 cells, stressEVs induced the downstream signaling of TLR4 and heme oxygenase 1 (HO-1) expression in H9c2 cells. StressEVs decreased necrosis due to simulated ischemia/reperfusion injury in H9c2 and AC16 cells, which was independent of TLR4 induction, but not that of HO-1. Calcium ionophore-induced EVs exert cytoprotection by inducing HO-1 in a TLR4-independent manner.
