Injectable and conductive cardiac patches repair infarcted myocardium in rats and minipigs.

Cardiac patches can help to restore the electrophysiological properties of the heart after myocardial infarction. However, scaffolds for the repair of heart muscle typically require surgical implantation or, if they are injectable, they are not electrically conductive or do not maintain their shape or function. Here, we report the performance, as demonstrated for the repair of infarcted heart muscle in rats and minipigs, of injectable and conductive scaffolds consisting of methacrylated elastin and gelatin, and carbon nanotubes that display shape-memory behaviour, a hierarchical porous structure and a negligible Poisson's ratio. In rats, the implantation of cell-free patches or patches seeded with rat cardiomyocytes onto the myocardium after ligation of the left anterior descending coronary artery led to functional repair after 4 weeks, as indicated by increases in fractional shortening and the ejection fraction, and by a decrease in the infarcted area. We also observed measures of functional recovery in minipigs with infarcted hearts after the delivery of cell-free patches or patches incorporating cardiomyocytes differentiated from human pluripotent stem cells.

IL-25-induced shifts in macrophage polarization promote development of beige fat and improve metabolic homeostasis in mice.

Beige fat dissipates energy and functions as a defense against cold and obesity, but the mechanism for its development is unclear. We found that interleukin (IL)-25 signaling through its cognate receptor, IL-17 receptor B (IL-17RB), increased in adipose tissue after cold exposure and ß3-adrenoceptor agonist stimulation. IL-25 induced beige fat formation in white adipose tissue (WAT) by releasing IL-4 and IL-13 and promoting alternative activation of macrophages that regulate innervation and up-regulate tyrosine hydroxylase (TH) up-regulation to produce more catecholamine including norepinephrine (NE). Blockade of IL-4Rα or depletion of macrophages with clodronate-loaded liposomes in vivo significantly impaired the beige fat formation in WAT. Mice fed with a high-fat diet (HFD) were protected from obesity and related metabolic disorders when given IL-25 through a process that involved the uncoupling protein 1 (UCP1)-mediated thermogenesis. In conclusion, the activation of IL-25 signaling in WAT may have therapeutic potential for controlling obesity and its associated metabolic disorders.

Aged Monkeys Fed a High-Fat/High-Sugar Diet Recapitulate Metabolic Disorders and Cardiac Contractile Dysfunction.

Aged nonhuman primate (NHP) models are of great value for studying the pathology of metabolic heart diseases and developing therapeutic strategies. In this study, aged male cynomolgus monkeys were fed a regular diet or a high-fat/high-sugar diet (HFSD) for 8 months. Metabolic disorders were diagnosed by 1H-NMR and serum biochemistry, and cardiac function was evaluated by echocardiography. Our results showed that serum metabolic profiles were altered in aged monkeys fed a HFSD, in line with aortic tissue damage, cardiac remodeling, and contractile dysfunction. This aged monkey model significantly increased expression of proinflammatory cytokines and altered expression and phosphorylation of intracellular signaling proteins in the heart, as compared to aged monkeys on a regular diet. Furthermore, the animals demonstrated increased phosphorylation of cardiac myofilament proteins which are causatively associated with decreased myofilament contractility. We conclude that the aged monkey model fed a HFSD exhibits metabolic disorders and cardiac contractile dysfunction.

Left ventricular response in the transition from hypertrophy to failure recapitulates distinct roles of Akt, ß-arrestin-2, and CaMKII in mice with aortic regurgitation.

BACKGROUND: Although aortic regurgitation (AR) is a clinically important condition that is becoming increasingly common, few relevant murine models and mechanistic studies exist for this condition. In this study, we attempted to delineate the pathological and molecular changes and address the roles of some potentially relevant molecules in an animal model of surgically induced AR. METHODS: AR was induced by puncturing the aortic valve leaflets in C57BL/6J mice under echocardiographic guidance. RESULTS: As early as 1 week following AR, the left ventricles (LV) displayed marked impairments in diastolic function and coronary flow reserve (CFR), as well as cardiac hypertrophy and chamber dilatation at both end-systole and end-diastole. LV free wall thickening and cardiomyocyte hypertrophy in LV were observed 2 weeks following of AR while a decline in ejection fraction was not seen until after 4 weeks. Nppa (natriuretic peptide A) and Nppb (natriuretic peptide B) increased over time, in conjunction with prominent Akt activation as well as slight CaMKII (Ca2+/calmodulin-dependent protein kinase II) activation and biphasic changes in ß-arrestin-2 expression. Treatment of AR mice with Akt inhibition exacerbated the eccentric hypertrophy, while neither inhibition of CaMKII nor ß-arrestin-2 overexpression influenced the response to AR. CONCLUSIONS: Our structural, functional, molecular and therapeutic analyses reveal that Akt, but not CaMKII or ß-arrestin-2, plays a regulatory role in the development of LV remodeling after AR in Mice. These results may shed important light on therapeutic targets for volume overloaded cardiomyopathy.

MiR-590-3p regulates proliferation, migration and collagen synthesis of cardiac fibroblast by targeting ZEB1.

Previous studies have implicated the attractive and promising role of miR-590-3p to restore the cardiac function following myocardial infarction (MI). However, the molecular mechanisms for how miR-590-3p involves in cardiac fibrosis remain largely unexplored. Using human cardiac fibroblasts (HCFs) as the cellular model, luciferase report assay, mutation, EdU assay and transwell migration assay were applied to investigate the biological effects of miR-590-3p on the proliferation, differentiation, migration and collagen synthesis of cardiac fibroblasts. We found that miR-590-3p significantly suppressed cell proliferation and migration of HCFs. The mRNA and protein expression levels of α-SMA, Col1A1 and Col3A were significantly decreased by miR-590-3p. Moreover, miR-590-3p directly targeted at the 3'UTR of ZEB1 to repress the translation of ZEB1. Interfering with the expression of ZEB1 significantly decreased the cell proliferation, migration activity, mRNA and protein expressions of α-SMA, Col1A1 and Col3A. Furthermore, the expressions of miR-590-3p and ZEB1 were identified in infarct area of MI model in pigs. Collectively, miR-590-3p suppresses the cell proliferation, differentiation, migration and collagen synthesis of cardiac fibroblasts by targeting ZEB1. These works will provide useful biological information for future studies on potential roles of miR-590-3p as the therapeutic target to recover cardiac function following MI.

MiR-144-3p Enhances Cardiac Fibrosis After Myocardial Infarction by Targeting PTEN.

Myocardial infarction (MI) may cause heart failure and seriously harm human health. During the genesis of cardiac fibrosis after MI, the proliferation and migration of cardiac fibroblasts contribute to secretion and maintenance of extracellular matrix (ECM) components. Many miRNAs have been highly implicated in the processes of cardiac fibrosis after MI. However, the molecular mechanisms for how miRNAs involve in cardiac fibrosis remain largely unexplored. Based on MI model in miniature pigs, the potential miRNAs involved in MI were identified by using small RNA sequencing. Using human cardiac fibroblasts (HCFs) as a cellular model, EdU, Transwell, and the expression of ECM-related proteins were applied to investigate the cell proliferation, migration and collagen synthesis. In this study, using MI model based on miniature pigs, 84 miRNAs were identified as the differentially expressed miRNAs between MI and control group, and miR-144-3p, one of differentially expressed miRNAs, was identified to be higher expressed in infarct area. The cell proliferation, migration activity, and the mRNA and protein levels of the ECM-related genes were significantly increased by miR-144-3p mimic but significantly decreased by miR-144-3p inhibitor in cardiac fibroblasts. Furthermore, miR-144-3p was observed to repress transcription and translation of PTEN, and interfering with the expression of PTEN up-regulated the mRNAs and proteins levels of α-SMA, Col1A1, and Col3A1, and promoted the proliferation and migration of cardiac fibroblasts, which was in line with that of miR-144-3p mimics, but this observation could be reversed by miR-144-3p inhibitor. Collectively, miR-144-3p promotes cell proliferation, migration, and collagen production by targeting PTEN in cardiac fibroblasts, suggesting that miR-144-3p-mediated-PTEN regulation might be a novel therapeutic target for cardiac fibrosis after MI.

Tanshinoneâ ¡A phenanthroimidazole derivative polarizes macrophage to improve metabolic homeostasis.

Macrophages infiltrated in adipose tissue play a key role in obesity. Some traditional pharmaceutical compounds may shift the polarization of recruited macrophages to improve metabolic homeostasis. TanshinoneⅡA (TAN2A) is a major active component of Salvia miltiorrhiza, a traditional anti-inflammatory cardiovascular medicine. In our study, we firstly constructed a phenanthroimidazole derivative of TAN2A named TAN20 by chemical synthesis, then identified its structure by chromatography and hydrogen spectroscopy, and finally examined its effects on immunometabolic responses. We found that TAN20 significantly induced the alternatively-activated (M2) rather than the classically-activated macrophages (M1), mainly through releasing the type II cytokines. Such effects were more pronounced than that from TAN2A. Compared to TAN2A, TAN20 substantially reduced body weight, decreased serum free fatty acid and HOMA-IR, and increased insulin sensitivity in obesity-induced diabetic mice. These effects of TAN20 were further validated on diabetic cynomolgus monkeys, which are closer to human physiological conditions. Taken together, our findings explicitly showed that TAN20 significantly polarized the macrophage and improved metabolic homeostasis in obesity-induced diabetic models, suggesting that TAN20 may be a potential drug against diabetes and obesity.

IL-25 stimulates M2 macrophage polarization and thereby promotes mitochondrial respiratory capacity and lipolysis in adipose tissues against obesity.

Obesity and associated metabolic diseases are characterized by a chronic low-grade inflammatory state with the infiltration of many inflammatory cells, especially macrophages. Immune molecules, including some cytokines, have a close relationship with metabolism. Interleukin (IL)-25 is a member of the IL-17 cytokine family that can regulate macrophages and alleviate some metabolic dysfunction; however, its role and mechanisms in lipid metabolism remain to be extensively clarified. Human serum and liver biopsy specimens, high-fat diet-induced obesity mice and DB/DB (Lepr-/-) animal models were used to examine IL-25 expression in obesity and nonalcoholic fatty liver diseases (NAFLD). To observe the role of IL-25 in lipid metabolism, model mice were administered with IL-25 or adoptively transferred with IL-25-educated macrophages in vivo, whereas bone marrow-derived macrophages, the macrophage cell line RAW264.7 and adipocytes differentiated from 3T3-L1 were used in vitro. IL-25 was decreased in NAFLD patients and obese mice. In addition, IL-25 reduced body weight gain and lipid accumulation, enhanced lipid uptake by macrophages and increased the expression of lipolysis and ß-oxidation enzymes via alternatively activating macrophages. IL-25 also promoted lipolysis and suppressed lipogenesis in adipocytes co-cultured with the IL-25-educated macrophages. Furthermore, IL-25 improved the mitochondrial respiratory capacity and oxygen consumption rate of macrophages and produced more NAD+/NADH and ATP. In conclusion, IL-25 can stimulate M2 macrophage polarization and thereby promote lipolysis and mitochondrial respiratory capacity, highlighting the potential for IL-25 to be used as a therapeutic agent against obesity and associated metabolic syndromes.