Animal Models Of Heart Failure Research Articles

Optimizing the Use of iPSC-CMs for Cardiac Regeneration in Animal Models.

Simple SummaryIn 2006, the first induced pluripotent stem cells were generated by reprogramming skin cells. Induced pluripotent stem cells undergo fast cell division, can differentiate into many different cell types, can be patient-specific, and do not raise ethical issues. Thus, they offer great promise as in vitro disease models, drug toxicity testing platforms, and for autologous tissue regeneration. Heart failure is one of the major causes of death worldwide. It occurs when the heart cannot meet the body’s metabolic demands. Induced pluripotent stem cells can be differentiated into cardiac myocytes, can form patches resembling native cardiac tissue, and can engraft to the damaged heart. However, despite correct host/graft coupling, most animal studies demonstrate an arrhythmogenicity of the engrafted tissue and variable survival. This is partially because of the heterogeneity and immaturity of the cells. New evidence suggests that by modulating induced pluripotent stem cells-cardiac myocytes (iPSC-CM) metabolism by switching substrates and changing metabolic pathways, you can decrease iPSC-CM heterogeneity and arrhythmogenicity. Novel culture methods and tissue engineering along with animal models of heart failure are needed to fully unlock the potential of cardiac myocytes derived from induced pluripotent stem cells for cardiac regeneration.Heart failure (HF) is a common disease in which the heart cannot meet the metabolic demands of the body. It mostly occurs in individuals 65 years or older. Cardiac transplantation is the best option for patients with advanced HF. High numbers of patient-specific cardiac myocytes (CMs) can be generated from induced pluripotent stem cells (iPSCs) and can possibly be used to treat HF. While some studies found iPSC-CMS can couple efficiently to the damaged heart and restore cardiac contractility, almost all found iPSC-CM transplantation is arrhythmogenic, thus hampering the use of iPSC-CMs for cardiac regeneration. Studies show that iPSC-CM cultures are highly heterogeneous containing atrial-, ventricular- and nodal-like CMs. Furthermore, they have an immature phenotype, resembling more fetal than adult CMs. There is an urgent need to overcome these issues. To this end, a novel and interesting avenue to increase CM maturation consists of modulating their metabolism. Combined with careful engineering and animal models of HF, iPSC-CMs can be assessed for their potential for cardiac regeneration and a cure for HF.

Association between Circular RNA CDR1as and Post-Infarction Cardiac Function in Pig Ischemic Heart Failure: Influence of the Anti-Fibrotic Natural Compounds Bufalin and Lycorine.

Anti-fibrotic therapies are of increasing interest to combat cardiac remodeling and heart failure progression. Recently, anti-fibrotic circular RNAs (circRNAs) have been identified in human and rodent cardiac tissue. In vivo (rodent) experiments proved cardiac anti-fibrotic effects of the natural compounds bufalin and lycorine by downregulating miRNA-671-5p, associated with a theoretic increase in the tissue level of circRNA CDR1as. Accordingly, we hypothesized that both anti-fibrotic drugs may inhibit focal myocardial fibrosis of the remodeled left ventricle (LV) also in a translational large animal model of heart failure (HF). Domestic pigs were repeatedly treated with subcutaneous injections of either bufalin, lycorine, or saline, (n = 5/group) between days 7–21 post acute myocardial infarction (AMI). At the 2-month follow-up, both bufalin and lycorine led to significantly reduced cardiac fibrosis. Bufalin treatment additionally led to smaller end-diastolic volumes, higher LV ejection fraction (EF), and increased expression of CDR1as of the AMI region. Elevated tissue levels of the circRNA CDR1as in the AMI region of the pig heart correlated significantly with LV and right ventricular EF, LV stroke volume, and negatively with infarct size. In conclusion, we successfully identified the circRNA CDR1as in pig hearts and show a significant association with improved LV and RV function by anti-fibrotic therapies in a translational animal model of HF.

Venoarterial Extracorporeal Membrane Oxygenation.

Venoarterial Extracorporeal Membrane Oxygenation.

Effect of Short-Term L-Thyroxine Therapy on Left Ventricular Mechanics in Idiopathic Dilated Cardiomyopathy

Previous experimental studies have provided evidence of notable changes in thyroid hormone signaling that corresponds to alterations in myocardial function in animal models of heart failure (HF). The present study further explores whether oral thyroid hormone treatment can change left ventricular (LV) mechanics and functional status in patients with idiopathic dilated cardiomyopathy (IDCM) or not. Sixty IDCM patients who were receiving conventional HF treatment were randomized to oral L-thyroxine (n=40) or placebo (n=20) for 3months. Fifty-two (86.7%) of all IDCM patients were symptomatic, their mean age was 41±12years, and their ejection fraction was 32%±7%. At baseline, the two groups were comparable in clinical and echocardiographic variables. Vector velocity imaging was utilized to assess LV mechanics. Myocardial longitudinal peak systolic strain, systolic strain rate, early and late diastolic strain rate, circumferential strain, LV dyssynchrony, plasma tri-iodothyronine, thyroxine, and thyroid stimulating hormonelevels were measured at baseline and 3months after treatment. All patients receiving L-thyroxine significantly improved in functional status (New York Heart Association class; P<.001) and echocardiographic parameters including end-diastolic diameter (P<.001), end-systolic diameter (P<.001), mitral regurgitation severity reduction (P<.001), and increased ejection fraction (P<.001). Left ventricular mechanics showed marked improvement at segmental and global levels of both longitudinal and circumferential myocardial strain (P<.005) when compared with placebo group. Short-term L-thyroxine therapy is well tolerated in IDCM patients. It improves cardiac mechanics and functional status, which might support the potential role of synthetic thyroid hormones in HF treatment.

MiR-181c protects cardiomyocyte injury by preventing cell apoptosis through PI3K/Akt signaling pathway.

Cardiomyocyte apoptosis plays an important role in the development of heart failure, which leads to high mortality in patients with cardiovascular diseases. In this study, we are focused to identify the role of miRNA-181c in the regulating of myocardial tissue apoptosis in the doxorubicin (DOX) or hypoxia/reoxygenation (H/R) induced H9C2 cardiomyocyte injury. DOX-induced heart failure animal model was established using mice. Total RNA was extracted from tissue and cell using Trizol. RT-PCR was conducted for real-time RNA quantification. H9c2 cells were collected and labeled using an Annexin V-PI apoptosis kit. Flow cytometry was conducted to identify the cell apoptosis. Rat cardiomyocyte H9c2 cell was treated by 16 hours' hypoxia and 2 hours' reoxygenation to induce cell apoptosis. TUNEL assay was employed for myocardial tissue apoptosis analysis. It was revealed that miR-181c was suppressed on the heart tissue of DOX-induced heart failure animal model. We observed miR-181c overexpression reduced apoptosis through TUNEL assay, which suggested the inhibitory effect of miR-181c on myocardial tissue apoptosis. Transfection of miR-181c mimic could decrease cell apoptosis in H/R treated H9C2 cells in vitro. Under the stimulation of H/R or DOX, miR-181c could downregulate protein expression of Fas, IL-6 and TNF-α, and upregulated Bcl2 and the phosphorylation of Akt. Our study revealed that miR-181c protected heart failure by impeding cardiomyocyte apoptosis through PI3K/Akt pathway, implying the therapeutic role of miR-181c during the exacerbation of the cardiovascular disease.

Revealing the synergistic mechanism of Shenfu Decoction for anti-heart failure through network pharmacology strategy.

The present study was designed to investigate the targets and synergistic mechanism of Shenfu Decoction (SFD) in the treatment of heart failure. A heart failure animal models was established to evaluate the pharmacological effects of SFD for anti-heart failure, then constructed ingredient-target interaction network by developing ingredient and target databases, the Discovery sdudio software was used for molecular docking. In addition, we validated the predicted protein targets of active ingredients in SFD by using surface plasmon resonance (SPR) technology. Our results demonstrated that SFD could enhance ejection fraction, alleviate myocardial histopathological characteristics, and reduce the level of angiotensin converting enzyme (ACE), aldosterone (ALD), atrial natriuretic polypeptide (ANP) and Renin (REN) in heart failure rat model. In addition, the ingredient database including 349 constituents and target database including 236 proteins were established, and 75 proteins were screened and identified by molecular docking strategy. 22 core target proteins were identified through network pharmacology, and the component-core target network was constructed. Finally, the affinity between the compounds and targets were verified by the SPR analysis method. The present study suggested that SFD may act on ACE 2, REN, ACE, ICAM-1, EGF, HTR2B, PARP1, NPPB and other proteins through AC, BAC, ACN, Re, Rg1, Rb1 to exert synergistic effects against heart failure.

Pharmacodynamic and pharmacokinetic effects of S086, a novel angiotensin receptor neprilysin inhibitor

Background and PurposeAngiotensin receptor-NEP inhibitor (ARNi), which includes an angiotensin receptor blocker (ARB) and a neprilysin inhibitor (NEPi), has been proven safe and effective for treating heart failure with reduced ejection fraction (HF-REF). S086 is a novel single-molecule ARNi that includes the molecular moieties of EXP3174 (the active metabolite of the ARB losartan) and sacubitril (a NEP inhibitor prodrug) in a 1:1 M ratio. We performed preclinical animal model studies to evaluate the efficacy of S086 in treating HF. Experimental ApproachRat and dog models of myocardial ischemia-induced chronic heart failure were used in this research. Principal ResultsThe oral administration of S086 dose-dependently lowered the heart weight index, attenuated cardiac fibrosis, and improved left ventricular ejection fraction, shortening fraction, and cardiac output, without effects on hemodynamics in animal models of myocardial ischemia-induced chronic heart failure. A comparable protective effect to LCZ696 was observed for S086 at an equal molar dose in dog models. In addition, S086 was superior to LCZ696 since it significantly reversed the decrease in left ventricular posterior wall end-systolic thickness. ConclusionThis animal study suggests that S086 is effective in treating myocardial ischemia-induced chronic heart failure.

Redox à la carte: Novel chemogenetic models of heart failure.

Many current animal models of heart failure are hampered by intrinsic methodological complexities, while other models yield only a subtle cardiac phenotype even after prolonged in vivo treatments. A new 'chemogenetic' animal model of heart failure reproduces a critical characteristic shared by many disease states that lead to heart failure in humans: an increase in redox stress in the heart. This 'chemogenetic' approach exploits a recombinant yeast enzyme that can be dynamically and specifically activated in vivo to generate the ROS hydrogen peroxide (H2 O2 ) in cardiac myocytes. Redox stress can be rapidly, selectively and reversibly manipulated by chemogenetic generation of ROS in cardiac myocytes, yielding a new model of dilated cardiomyopathy. Treatment of animals with the angiotensin receptor antagonist valsartan promotes recovery of ventricular function and resolution of adverse cardiac remodelling. This mini-review discusses in vivo chemogenetic approaches to manipulate and analyse oxidative stress in the heart.

Establishing a Swine Model of Post-myocardial Infarction Heart Failure for Stem Cell Treatment.

Although advances have been achieved in the treatment of heart failure (HF) following myocardial infarction (MI), HF following MI remains one of the major causes of mortality and morbidity around the world. Cell-based therapies for cardiac repair and improvement of left ventricular function after MI have attracted considerable attention. Accordingly, the safety and efficacy of these cell transplantations should be tested in a preclinical large animal model of HF prior to clinical use. Pigs are widely used for cardiovascular disease research due to their similarity to humans in terms of heart size and coronary anatomy. Therefore, we sought to present an effective protocol for the establishment of a porcine chronic HF model using closed-chest coronary balloon occlusion of the left circumflex artery (LCX), followed by rapid ventricular pacing induced with pacemaker implantation. Eight weeks later, the stem cells were administered by intramyocardial injection in the peri-infarct area. Then the infarct size, cell survival, and left ventricular function (including echocardiography, hemodynamic parameters, and electrophysiology) were evaluated. This study helps establish a stable preclinical large animal HF model for stem cell treatment.

Increasing carbohydrate oxidation improves contractile reserves and prevents hypertrophy in porcine right heart failure

In heart failure, myocardial overload causes vast metabolic changes that impair cardiac energy production and contribute to deterioration of contractile function. However, metabolic therapy is not used in heart failure care. We aimed to investigate the interplay between cardiac function and myocardial carbohydrate metabolism in a large animal heart failure model. Using magnetic resonance spectroscopy with hyperpolarized pyruvate and magnetic resonance imaging at rest and during pharmacological stress, we investigated the in-vivo cardiac pyruvate metabolism and contractility in a porcine model of chronic pulmonary insufficiency causing right ventricular volume overload. To assess if increasing the carbohydrate metabolic reserve improves the contractile reserve, a group of animals were fed dichloroacetate, an activator of pyruvate oxidation. Volume overload caused heart failure with decreased pyruvate dehydrogenase flux and poor ejection fraction reserve. The animals treated with dichloroacetate had a larger contractile response to dobutamine stress than non-treated animals. Further, dichloroacetate prevented myocardial hypertrophy. The in-vivo metabolic data were validated by mitochondrial respirometry, enzyme activity assays and gene expression analyses. Our results show that pyruvate dehydrogenase kinase inhibition improves the contractile reserve and decreases hypertrophy by augmenting carbohydrate metabolism in porcine heart failure. The approach is promising for metabolic heart failure therapy.

From traditional pharmacological towards nucleic acid-based therapies for cardiovascular diseases.

Nucleic acid-based therapeutics are currently developed at large scale for prevention and management of cardiovascular diseases (CVDs), since: (i) genetic studies have highlighted novel therapeutic targets suggested to be causal for CVD; (ii) there is a substantial recent progress in delivery, efficacy, and safety of nucleic acid-based therapies; (iii) they enable effective modulation of therapeutic targets that cannot be sufficiently or optimally addressed using traditional small molecule drugs or antibodies. Nucleic acid-based therapeutics include (i) RNA-targeted therapeutics for gene silencing; (ii) microRNA-modulating and epigenetic therapies; (iii) gene therapies; and (iv) genome-editing approaches (e.g. CRISPR-Cas-based): (i) RNA-targeted therapeutics: several large-scale clinical development programmes, using antisense oligonucleotides (ASO) or short interfering RNA (siRNA) therapeutics for prevention and management of CVD have been initiated. These include ASO and/or siRNA molecules to lower apolipoprotein (a) [apo(a)], proprotein convertase subtilisin/kexin type 9 (PCSK9), apoCIII, ANGPTL3, or transthyretin (TTR) for prevention and treatment of patients with atherosclerotic CVD or TTR amyloidosis. (ii) MicroRNA-modulating and epigenetic therapies: novel potential therapeutic targets are continually arising from human non-coding genome and epigenetic research. First microRNA-based therapeutics or therapies targeting epigenetic regulatory pathways are in clinical studies. (iii) Gene therapies: EMA/FDA have approved gene therapies for non-cardiac monogenic diseases and LDL receptor gene therapy is currently being examined in patients with homozygous hypercholesterolaemia. In experimental studies, gene therapy has significantly improved cardiac function in heart failure animal models. (iv) Genome editing approaches: these technologies, such as using CRISPR-Cas, have proven powerful in stem cells, however, important challenges are remaining, e.g. low rates of homology-directed repair in somatic cells such as cardiomyocytes. In summary, RNA-targeted therapies (e.g. apo(a)-ASO and PCSK9-siRNA) are now in large-scale clinical outcome trials and will most likely become a novel effective and safe therapeutic option for CVD in the near future. MicroRNA-modulating, epigenetic, and gene therapies are tested in early clinical studies for CVD. CRISPR-Cas-mediated genome editing is highly effective in stem cells, but major challenges are remaining in somatic cells, however, this field is rapidly advancing.

Galectin-3: A Cardiomyocyte Antiapoptotic Mediator at 24-Hour Post Myocardial Infarction.

Galectin 3 (GAL-3) is a beta galactoside binding lectin that has different roles in normal and pathophysiological conditions. GAL-3 has been associated with heart failure and was linked to increased risk of death in a number of studies. GAL-3 was found to be up regulated in animal models of heart failure as well as myocardial infarction (MI). The objective of his study is to test if high GAL-3 after myocardial infarction has a protective role on the heart through its anti-apoptotic and anti-necrotic functions. Male C57B6/J mice and GAL-3 knockout (KO) mice were used for permanent ligation of the left anterior descending artery of the heart to create infarction in the anterior myocardium. Heart and plasma samples were collected 24 hours after the induction of MI and were used for immunohistochemistry, Tunnel procedure, electron microscopy and enzyme linked immunosorbent assay (ELISA). Our results show that the significant increase in GAL-3 levels in the left ventricle at 24-hour following MI is associated with significant lower levels of pro-apoptotic proteins; cytochrome c, Bax, annexin V, cleaved caspase-3 and a higher levels of anti-apoptotic protein Bcl2 in GAL-3 wild MI group than GAL-3 KO group. We also have identified the anti-apoptotic activity of GAL-3 is mediated through a significant increase in Akt-1, NF kappa-B and beta- catenin proteins. In addition, we have identified the antiapoptotic activity is mediated through a significant lower levels of cathepsin-D protein. We conclude that the increased levels of GAL-3 at 24-hour following MI regulate antiapoptotic mechanisms in the myocardium that will shape the future course of the disease. We also identified that the anti-apoptotic mechanisms are likely mediated through interaction of GAL-3 with Akt-1, NF kappa-B, beta- catenin and cathepsin D proteins.

Effects of Central Intervention of Tumor Necrosis Factor‐α Converting Enzyme (TACE) on Neuroinflammation and Cardiac Function in Heart Failure

Central nervous system inflammation has been implicated in the neurohumoral activation and disease progression in experimental animal models of heart failure (HF). The pro‐inflammatory cytokine tumor necrosis factor‐α (TNF‐α) increases in cardiovascular/autonomic brain regions including the paraventricular nucleus of the hypothalamus (PVN) and subfornical organ (SFO), and contributes significantly to the augmented sympathetic nerve activity in HF. TNF‐α is initially synthesized as a membrane bound protein that is proteolytically cleaved by TNF‐α converting enzyme (TACE), also known as a disintegrin and metalloprotease 17 (ADAM17), to become the fully functional inflammatory mediator. Our previous study demonstrated that TACE has elevated expression in the PVN and SFO and mediates TNF‐α‐induced sympathetic excitation and hemodynamic responses in HF rats. However, whether inhibition of TACE in the brain has a protective effect on central inflammation and cardiac function in HF remains unclear. We hypothesized that inhibition of TACE activity in the brain reduces central inflammation and improves left ventricular (LV) function during HF. Adult male Sprague‐Dawley rats were studied 4–5 weeks after induction of HF by coronary artery ligation. TACE activity was chronically inhibited specifically in the brain by infusion of the TACE inhibitor TAPI‐1 (30μg/day) via an osmotic minipump connected to an intracerebroventricular (ICV) cannula. Treatment with TAPI‐1 or vehicle began immediately following the myocardial infarction. At the end of experiments, LV function was assessed by echocardiography and tissues were collected for molecular analysis. In HF rats‐treated with TAPI‐1, the LV ejection fraction (26.8±0.9% vs 34.8±6.4%) was improved, although this did not reach statistical significance vs. HF treated with vehicle. Wet lung weight to body weight ratio also showed a trend towards being improved in TAPI‐1 treated animals (6.3±0.3mg/g vs. 4.8±0.4mg/g, vehicle vs. TAPI‐1, p=0.32). Additionally, TAPI‐1 treatment significantly decreased mRNA levels of proinflammatory mediators including TNF‐α, IL‐1β, and TACE in the SFO (TNF‐α: 0.28±0.10, p&lt;0.05; IL1‐β: 0.25±0.11, p&gt;0.05; TACE: 0.68±0.14, p&lt;0.05, fold change vs. vehicle) and resulted in a trend toward reduced levels of these measurements in the PVN (TNF‐α: 0.52±0.13, p=0.24; IL1‐β: 0.58±0.11, p=0.21; TACE: 0.87±0.11, p=0.43, fold change vs. vehicle). TNF‐α expression was also reduced in both the superior cervical (0.35±0.07, p&lt;0.05, fold change vs. vehicle) and stellate ganglia (0.44±0.14, p&lt;0.05 fold change vs. vehicle). Taken together, these data suggest that central inhibition of TACE activity diminishes the inflammatory state in the brain and improve cardiac function in HF.

Development and Characterization of a Novel Small Animal Model of Heart Failure with Preserved Ejection Fraction

Heart Failure with Preserved Ejection Fraction (HFpEF) is a complex heterogeneous disease that currently affects approximately 3 million in the US and accounts for 60% of all heart failure hospitalizations. HFpEF is associated with significant morbidity, mortality and healthcare expenditures. At present, there are no FDA approved therapies for reducing mortality and hospitalization in HFpEF patients. The lack of approved therapies is due in part to a lack of preclinical models that faithfully mimic the clinical presentation of HFpEF.The obese ZSF‐1 rat is genetically predisposed to the development of hypertension, obesity, dyslipidemia, and diabetes, all of which contribute to the pathogenesis of HFpEF. We investigated the suitability of the obese ZSF‐1 rat as a model of HFpEF. Both obese and lean control ZSF‐1 rats (n = 4–6 per group) were utilized for these studies. The rats were studied from 16 weeks to 24 weeks of age. We measured several clinical parameters including cardiac structure and function (2‐D echocardiography), left ventricular (LV) pressures (LV Millar catheter), cardiac fibrosis, conscious blood pressure and heart rate (DSI radiotelemeters), vascular function, exercise capacity (rodent treadmill), and serum lipid and triglyceride levels (standard blood ELISA assays).Obese ZSF‐1 rats exhibited a significant increase in body weight and systemic blood pressure combined with hyperglycemia and insulin insensitivity. Echocardiographic evaluation of the left ventricle (LV) revealed highly significant increases in both the E/A and E/E′ ratios. LV end‐diastolic pressure (LVEDP) and LV relaxation (Tau) were decreased in the obese ZSF‐1 rats. Histological evaluation of the hearts revealed significant increases in cardiac fibrosis and cardiac myocyte injury in the obese vs. lean ZSF‐1. Furthermore, vascular reactivity and circulating nitric oxide levels were reduced in the obese ZSF‐1 rats. Exercise capacity testing revealed that exercise capacity was very significantly reduced in the ZSF‐1 obese rat throughout the 8 week experimental protocol. All these findings are consistent with the HFpEF phenotype observed in human HFpEF patients.This preclinical model of HFpEF, will provide novel insights into the pathobiology of HFpEF and provide a critically important platform for testing HFpEF therapeutics. Our future studies will be aimed at the identification of novel therapeutic interventions to treat HFpEF.Support or Funding InformationNational Institutes of General Medical Sciences (NIGMS) COBRE grant no. P30GM106392 to Dr. KapustaFigure 1

Regulation of Coronary Blood Flow by the Carotid Body Chemoreceptors in Ovine Heart Failure

BackgroundThe carotid body (CB) is an arterial chemoreceptor organ located in the carotid bifurcation, which carries out essential functions in cardiorespiratory control. In response to hypoxia, carotid chemosensory discharge produces respiratory, autonomic, and cardiovascular adjustments critical for body homeostasis. Previous studies have shown that chemoreflex sensitivity is augmented animal models of heart failure (HF). However, the role of the chemoreflex in modulating coronary blood flow during HF is not clear. We hypothesized that carotid chemoreceptor stimulation would increase coronary blood flow in both normal sheep and sheep with HF.MethodsHeart failure was induced by the microembolization technique and instrumentation was performed when ejection fraction was below 40%. Both groups of sheep were implanted with a coronary artery flow probe and an arterial pressure catheter. The responses of mean arterial pressure (MAP) and coronary blood flow (CoBF) were determined in conscious sheep following CB stimulation with intracarotid potassium cyanide (KCN; 30μg/kg). To determine the cardiac vagal contribution to the CoBF response, CB activation was repeated following atropine infusion (8 mg bolus followed by 24 mg/h infusion for 30 minutes).ResultsIn control animals, activation of the CB increased MAP (114±1%) and CoBF (116±4%) but coronary vascular conductance (CVC) was unaltered. In the HF group, CB stimulation increased MAP (108±1%), CoBF (126±3%), and CVC (114±2%). The MAP increase was significantly attenuated after atropine infusion in both animal groups, however, the CoBF and CVC responses to KCN were unchanged. These responses persisted when the heart was paced at a constant rate to eliminate the role of altered metabolic demand.DiscussionOur data indicate that in an ovine model of HF, carotid body mediated increases in MAP are attenuated compared to control animals. There was a significant increase in coronary vascular conductance in the HF animals following CB activation which was absent in the normal animals. Overall, our data suggest that the hyperactive carotid body chemoreflex may serve to increase coronary blood flow in the HF condition.Support or Funding InformationHealth Research Council of New Zealand, National Heart Foundation of New Zealand

AntimiR-21 Prevents Myocardial Dysfunction in a Pig Model of Ischemia/Reperfusion Injury

BackgroundmiR-21 is a central regulator of cardiac fibrosis, and its inhibition in small-animal models has been shown to be an effective antifibrotic strategy in various organs, including the heart. Effective delivery of therapeutic antisense micro–ribonucleic acid (antimiR) molecules to the myocardium in larger organisms is challenging, though, and remains to be established for models of chronic heart failure. ObjectivesThe aims of this study were to test the applicability and therapeutic efficacy of local, catheter-based delivery of antimiR-21 in a pig model of heart failure and determine its effect on the cardiac transcriptomic signature and cellular composition. MethodsPigs underwent transient percutaneous occlusion of the left coronary artery and were followed up for 33 days. AntimiR-21 (10 mg) was applied by intracoronary infusion at days 5 and 19 after the injury. Cardiac function was assessed in vivo, followed by histological analyses and deep ribonucleic acid sequencing (RNA-seq) of the myocardium and genetic deconvolution analysis. ResultsAntimiR-21 effectively suppressed the remodeling-associated increase of miR-21. At 33 days after ischemia/reperfusion injury, LNA-21-treated hearts exhibited reduced cardiac fibrosis and hypertrophy and improved cardiac function. Deep RNA-seq revealed a significant derepression of the miR-21 targetome in antimiR-21-treated myocardium and a suppression of the inflammatory response and mitogen-activated protein kinase signaling. A genetic deconvolution approach built on deep RNA-seq and single-cell RNA-seq data identified reductions in macrophage and fibroblast numbers as the key cell types affected by antimiR-21 treatment. ConclusionsThis study provides the first evidence for the feasibility and therapeutic efficacy of miR-21 inhibition in a large animal model of heart failure.

Reprogramming Cardiac Cells Into Cardiac Purkinje‐like Cells For The Treatment Of Heart Failure

Heart failure (HF) is a chronic condition where the heart loses its ability to efficiently pump blood to other organs in the body. Currently, there is no cure for HF, other than a heart transplant, which may not be available for most patients. Other treatments available for HF focus on reducing the symptoms, but do not properly address the loss of cardiac tissue and scar tissue formation commonly observed in this condition. We believe that a novel therapeutic approach for HF can be achieved through direct administration of cardiac electrical conducting cells to failing hearts. This is because cardiac conducting cells, such as Purkinje cells, can intrinsically propagate electrical signals in synchronicity with other cardiac cells, allowing the heart to contract and pump blood. Thus, direct injection of cardiac Purkinje cells into failing hearts may overcome mechanical issues from scar tissue, as well as restore some of the cardiac tissue that has been lost in HF. To create Purkinje‐like cells, a reporter gene containing a Connexin 30.2 promoter and mCherry fluorescent tag was first introduced into the cardiac cells. This was followed by 5 days treatment with specific small molecules. The reprogrammed cardiac Purkinje‐like cells are then being characterized by transcriptome, epigenetic state, and functional analyses through FACS sorting, immunostaining, qPCR analysis, RNA sequencing, ChIP‐seq and Patch clamp. Successfully reprogrammed cardiac cells are expected to exhibit Purkinje‐like properties such as genetic make‐up and functionality. Upon creating Purkinje‐like cells, the next step will be to test the effectiveness of the Purkinje‐like cells in restoring the electrical conduction, as well as improving cardiac function, in small animal models of HF.Support or Funding InformationRobert J. Kleberg, Jr. and Helen C. Kleberg FoundationNational Heart, Lung, and Blood Institute (NHLBI) of the NIH (R15HL141963)

Protective effects of rimeporide on left ventricular function in golden retriever muscular dystrophy dogs

BackgroundAlterations in intracellular Na+ and Ca2+ have been observed in patients with Duchenne muscular dystrophy (DMD) and in animal models of DMD, and inhibition of Na+-H+ exchanger 1 (NHE1) by rimeporide has previously demonstrated cardioprotective effects in animal models of myocardial ischemia and heart failure. Since heart failure is becoming a predominant cause of death in DMD patients, this study aimed to demonstrate a cardioprotective effect of chronic administration of rimeporide in a canine model of DMD. MethodsGolden retriever muscular dystrophy (GRMD) dogs were randomized to orally receive rimeporide (10 mg/kg, twice a day) or placebo from 2 months to 1 year of age. Left ventricular (LV) function was assessed by conventional and advanced echocardiography. ResultsCompared with placebo-treated GRMD, LV function deterioration with age was limited in rimeporide-treated GRMD dogs as indicated by the preservation of LV ejection fraction as well as overall cardiac parameters different from placebo-treated dogs, as revealed by composite cardiac scores and principal component analysis. In addition, principal component analysis clustered rimeporide-treated GRMD dogs close to healthy control dogs. ConclusionsChronic administration of the NHE1 inhibitor rimeporide exerted a protective effect against LV function decline in GRMD dogs. This study provides proof of concept to explore the cardiac effects of rimeporide in DMD patients.

Pharmacological Silencing of MicroRNA-152 Prevents Pressure Overload-Induced Heart Failure.

MicroRNAs are small, noncoding RNAs that play a key role in gene expression. Accumulating evidence suggests that aberrant microRNA expression contributes to the heart failure (HF) phenotype; however, the underlying molecular mechanisms are not well understood. A better understanding of the mechanisms of action of microRNAs could potentially lead to targeted therapies that could halt the progression or even reverse HF. We found that microRNA-152 (miR-152) expression was upregulated in the failing human heart and experimental animal models of HF. Transgenic mice with cardiomyocyte-specific miR-152 overexpression developed systolic dysfunction (mean difference, -38.74% [95% CI, -45.73% to -31.74%]; P<0.001) and dilated cardiomyopathy. At the cellular level, miR-152 overexpression perturbed mitochondrial ultrastructure and dysregulated key genes involved in cardiomyocyte metabolism and inflammation. Mechanistically, we identified Glrx5 (glutaredoxin 5), a critical regulator of mitochondrial iron homeostasis and iron-sulfur cluster synthesis, as a direct miR-152 target. Finally, a proof-of-concept of the therapeutic efficacy of targeting miR-152 in vivo was obtained by utilizing a locked nucleic acid-based inhibitor of miR-152 (LNA 152) in a murine model of HF subjected to transverse aortic constriction. We demonstrated that animals treated with LNA-152 (n=10) showed preservation of systolic function when compared with locked nucleic acid-control treated animals (n=9; mean difference, 18.25% [95% CI, 25.10% to 11.39%]; P<0.001). The upregulation of miR-152 expression in the failing myocardium contributes to HF pathophysiology. Preclinical evidence suggests that miR-152 inhibition preserves cardiac function in a model of pressure overload-induced HF. These findings offer new insights into the pathophysiology of HF and point to miR-152-Glrx5 axis as a potential novel therapeutic target.

Highlights From the Circulation Family of Journals.

Highlights From the Circulation Family of Journals.