Apoptosis in the failing human heart

Rapamycin regulates the balance between cardiomyocyte apoptosis and autophagy in chronic heart failure by inhibiting mTOR signaling

The progressive loss of cardiomyocytes caused by cell death leads to cardiac dysfunction and heart failure (HF). Rapamycin has been shown to be cardioprotective in pressure-overloaded and ischemic heart diseases by regulating the mechanistic target of rapamycin (mTOR) signaling network. However, the impact of rapamycin on cardiomyocyte death in chronic HF remains undetermined. Therefore, in the current study we addressed this issue using a rat myocardial infarction (MI)-induced chronic HF model induced by ligating the coronary artery. Following surgery, rats were randomly divided into six groups, including the sham-, vehicle- and rapamycin-operated groups, at 8 or 12 weeks post-MI. A period of 4 weeks after MI induction, the rats were treated with rapamycin (1.4 mg-kg-day) or vehicle for 4 weeks. Cardiac function was determined using echocardiography, the rats were subsequently euthanized and myocardial tissues were harvested for histological and biochemical analyses. In the cell culture experiments with H9c2 rat cardiomyocytes, apoptosis was induced using angiotensin II (100 nM; 24 h). Cardiomyocyte apoptosis and autophagy were assessed via measuring apoptosis- and autophagy-associated proteins. The activities of mTOR complex 1 (mTORC1) and mTORC2 were evaluated using the phosphorylation states of ribosomal S6 protein and Akt, respectively. The activity of the endoplasmic reticulum (ER) stress pathway was determined using the levels of GRP78, caspase-12, phospho-JNK and DDIT3. Echocardiographic and histological measurements indicated that rapamycin treatment improved cardiac function and inhibited cardiac remodeling at 8 weeks post-MI. Additionally, rapamycin prevented cardiomyocyte apoptosis and promoted autophagy at 8 weeks post-MI. Rapamycin treatment for 4 weeks inhibited the mTOR and ER stress pathways. Furthermore, rapamycin prevented angiotensin II-induced H9c2 cell apoptosis and promoted autophagy by inhibiting the mTORC1 and ER stress pathways. These results demonstrated that rapamycin reduced cardiomyocyte apoptosis and promoted cardiomyocyte autophagy, by regulating the crosstalk between the mTOR and ER stress pathways in chronic HF.

Fundamental Mechanisms of Regulated Cell Death and Implications for Heart Disease

Twelve regulated cell death programs have been described. We review in detail the basic biology of nine including death receptor-mediated apoptosis, death receptor-mediated necrosis (necroptosis), mitochondrial-mediated apoptosis, mitochondrial-mediated necrosis, autophagy-dependent cell death, ferroptosis, pyroptosis, parthanatos, and immunogenic cell death. This is followed by a dissection of the roles of these cell death programs in the major cardiac syndromes: myocardial infarction and heart failure. The most important conclusion relevant to heart disease is that regulated forms of cardiomyocyte death play important roles in both myocardial infarction with reperfusion (ischemia/reperfusion) and heart failure. While a role for apoptosis in ischemia/reperfusion cannot be excluded, regulated forms of necrosis, through both death receptor and mitochondrial pathways, are critical. Ferroptosis and parthanatos are also likely important in ischemia/reperfusion, although it is unclear if these entities are functioning as independent death programs or as amplification mechanisms for necrotic cell death. Pyroptosis may also contribute to ischemia/reperfusion injury, but potentially through effects in non-cardiomyocytes. Cardiomyocyte loss through apoptosis and necrosis is also an important component in the pathogenesis of heart failure and is mediated by both death receptor and mitochondrial signaling. Roles for immunogenic cell death in cardiac disease remain to be defined but merit study in this era of immune checkpoint cancer therapy. Biology-based approaches to inhibit cell death in the various cardiac syndromes are also discussed.

In vivo detection of programmed cell death during mouse heart development

Despite the great progress on the cell biology of programmed cell death (PCD), its incidence and exact time course during embryonic and particular heart development are still unclear. This is also due to the lack of models enabling to directly identify and monitor PCD cells at different time points in vivo. Herein we report generation of transgenic murine embryonic stem cell and mouse models expressing secreted Annexin V-YFP under control of the CAG promoter. This enables to visualize and quantify PCD in vitro and in vivo during embryonic development. At early embryonic stages we found Annexin V-YFP⁺ fluorescent cells in known areas of PCD, such as the otic ring and at the site of neural tube closing, underscoring its specificity for detection of PCD. We have focused our detailed analysis primarily on PCD in the embryonic heart for a better understanding of its role during development. Our findings reveal that PCD peaks at early stages of cardiogenesis (E9.5-E13.5) and strongly decreases thereafter. Moreover, the PCD cells in the heart are predominantly cardiomyocytes, and an unexpected area of prominent cardiac PCD are the ventricular trabeculae (E9.5-E14.5). Thus, the sA5-YFP mouse line provides novel insight into the incidence and relevance of cardiac PCD during embryonic development ex- and in vivo.

Guidelines for evaluating myocardial cell death

Cell death is a fundamental process in cardiac pathologies. Recent studies have revealed multiple forms of cell death, and several of them have been demonstrated to underlie adverse cardiac remodeling and heart failure. With the expansion in the area of myocardial cell death and increasing concerns over rigor and reproducibility, it is important and timely to set a guideline for the best practices of evaluating myocardial cell death. There are six major forms of regulated cell death observed in cardiac pathologies, namely apoptosis, necroptosis, mitochondrial-mediated necrosis, pyroptosis, ferroptosis, and autophagic cell death. In this article, we describe the best methods to identify, measure, and evaluate these modes of myocardial cell death. In addition, we discuss the limitations of currently practiced myocardial cell death mechanisms.

Augmentation of myocardial If dysregulates calcium homeostasis and causes adverse cardiac remodeling

HCN channels underlie the depolarizing funny current (If) that contributes importantly to cardiac pacemaking. If is upregulated in failing and infarcted hearts, but its implication in disease mechanisms remained unresolved. We generated transgenic mice (HCN4tg/wt) to assess functional consequences of HCN4 overexpression-mediated If increase in cardiomyocytes to levels observed in human heart failure. HCN4tg/wt animals exhibit a dilated cardiomyopathy phenotype with increased cellular arrhythmogenicity but unchanged heart rate and conduction parameters. If augmentation induces a diastolic Na+ influx shifting the Na+/Ca2+ exchanger equilibrium towards 'reverse mode' leading to increased [Ca2+]i. Changed Ca2+ homeostasis results in significantly higher systolic [Ca2+]i transients and stimulates apoptosis. Pharmacological inhibition of If prevents the rise of [Ca2+]i and protects from ventricular remodeling. Here we report that augmented myocardial If alters intracellular Ca2+ homeostasis leading to structural cardiac changes and increased arrhythmogenicity. Inhibition of myocardial If per se may constitute a therapeutic mechanism to prevent cardiomyopathy.

Phospholipid oxidation products in ferroptotic myocardial cell death

Cell death is an important component of the pathophysiology of any disease. Myocardial disease is no exception. Understanding how and why cells die, particularly in the heart where cardiomyocyte regeneration is limited at best, becomes a critical area of study. Ferroptosis is a recently described form of nonapoptotic cell death. It is an iron-mediated form of cell death that occurs because of accumulation of lipid peroxidation products. Reactive oxygen species and iron-mediated phospholipid peroxidation is a hallmark of ferroptosis. To date, ferroptosis has been shown to be involved in cell death associated with Alzheimer’s disease, Huntington’s disease, cancer, Parkinson’s disease, and kidney degradation. Myocardial reperfusion injury is characterized by iron deposition as well as reactive oxygen species production. These conditions, therefore, favor the induction of ferroptosis. Currently there is no available treatment for reperfusion injury, which accounts for up to 50% of the final infarct size. This review will summarize the evidence that ferroptosis can induce cardiomyocyte death following reperfusion injury and the potential for this knowledge to open new therapeutic approaches for myocardial ischemia-reperfusion injury.

Nonocclusive multivessel intracoronary infusion of allogeneic cardiosphere-derived cells early after reperfusion prevents remote zone myocyte loss and improves global left ventricular function in swine with myocardial infarction

Intracoronary cardiosphere-derived cells (icCDCs) infused into the infarct-related artery reduce scar volume but do not improve left ventricular (LV) ejection fraction (LVEF). We tested the hypothesis that this reflects the inability of regional delivery to prevent myocyte death or promote myocyte proliferation in viable myocardium remote from the infarct. Swine (n = 23) pretreated with oral cyclosporine (200 mg/day) underwent a 1-h left anterior descending coronary artery (LAD) occlusion, which reduced LVEF from 61.6 ± 1.0 to 45.3 ± 1.5% 30 min after reperfusion. At that time, animals received global infusion of allogeneic icCDCs (n = 8), regional infusion of icCDCs restricted to the LAD using the stop-flow technique (n = 8), or vehicle (n = 7). After 1 mo, global icCDCs increased LVEF from 44.8 ± 1.9 to 60.8 ± 3.8% (P < 0.05) with no significant change after LAD stop-flow icCDCs (44.8 ± 3.6 to 50.9 ± 3.1%) or vehicle (46.5 ± 2.5 to 47.7 ± 2.6%). In contrast, global icCDCs did not alter infarct volume (%LV mass) assessed at 2 days (11.2 ± 2.3 vs. 12.6 ± 2.3%), whereas it was reduced after LAD stop-flow icCDCs (7.1 ± 1.1%, P < 0.05). Histopathological analysis of remote myocardium after global icCDCs demonstrated a significant increase in myocyte proliferation (147 ± 32 vs. 14 ± 10 nuclei/10⁶ myocytes, P < 0.05) and a reduction in myocyte apoptosis (15 ± 9 vs. 46 ± 10 nuclei/10⁶ myocytes, P < 0.05) that increased myocyte nuclear density (1,264 ± 39 vs. 1,157 ± 33 nuclei/mm², P < 0.05) and decreased myocyte diameter (13.2 ± 0.2 vs. 14.5 ± 0.3 μm, P < 0.05) compared with vehicle-treated controls. In contrast, remote zone changes after regional LAD icCDCs were no different from vehicle. These data indicate that changes in global LVEF after icCDCs are dependent upon preventing myocyte loss and hypertrophy in myocardium remote from the infarct. These arise from stimulating myocyte proliferation and reducing myocyte apoptosis indicating the importance of directing cell therapy to viable remote regions.NEW & NOTEWORTHY Administration of allogeneic cardiosphere-derived cells to the entire heart via global intracoronary infusion shortly after myocardial infarction favorably influenced left ventricular ejection fraction by preventing myocyte death and promoting myocyte proliferation in remote, noninfarcted myocardium in swine. In contrast, regional intracoronary cell infusion did not significantly affect remote zone myocyte remodeling. Global cell administration targeting viable myocardium remote from the infarct may be an effective approach to prevent adverse ventricular remodeling after myocardial infarction.

Advanced Evolution of Pathogenesis Concepts in Cardiomyopathies

Cardiomyopathy is a group of heterogeneous cardiac diseases that impair systolic and diastolic function, and can induce chronic heart failure and sudden cardiac death. Cardiomyopathy is prevalent in the general population, with high morbidity and mortality rates, and contributes to nearly 20% of sudden cardiac deaths in younger individuals. Genetic mutations associated with cardiomyopathy play a key role in disease formation, especially the mutation of sarcomere encoding genes and ATP kinase genes, such as titin, lamin A/C, myosin heavy chain 7, and troponin T1. Pathogenesis of cardiomyopathy occurs by multiple complex steps involving several pathways, including the Ras-Raf-mitogen-activated protein kinase-extracellular signal-activated kinase pathway, G-protein signaling, mechanotransduction pathway, and protein kinase B/phosphoinositide 3-kinase signaling. Excess biomechanical stress induces apoptosis signaling in cardiomyocytes, leading to cell loss, which can induce myocardial fibrosis and remodeling. The clinical features and pathophysiology of cardiomyopathy are discussed. Although several basic and clinical studies have investigated the mechanism of cardiomyopathy, the detailed pathophysiology remains unclear. This review summarizes current concepts and focuses on the molecular mechanisms of cardiomyopathy, especially in the signaling from mutation to clinical phenotype, with the aim of informing the development of therapeutic interventions.

Fas/FasL-mediated cell death in rat's diabetic hearts involves activation of calcineurin/NFAT4 and is potentiated by a high-fat diet rich in corn oil

This study investigated if calcineurin/nuclear factor of activated T cells (NFAT) axis mediates the cardiac apoptosis in rats with type 1 diabetes mellitus (T1DM)-induced rats or administered chronically high-fat diet rich in corn oil (CO-HFD). Also, it investigated the impact of chronic administration of CO-HFD on Fas/Fas ligand (Fas/FasL)-induced apoptosis in the hearts of T1DM-induced rats. Adult male Wistar rats (140-160 g) were classified as control: (10% fat) CO-HFD: (40% fat), T1DM, and T1DM + CO-HFD (n=20/each). In vitro, cardiomyocytes were cultured in either low glucose (LG) or high glucose (HG) media in the presence or absence of linoleic acid (LA) and other inhibitors. Compared to the control, increased reactive oxygen species (ROS), protein levels of cytochrome C, cleaved caspase-8 and caspase-3, myocardial damage and impeded left ventricular (LV) function were observed in the hearts of all treated groups and maximally in T1DM + CO-HFD-treated rats. mRNA of all NFAT members (NFAT1-4) were not affected by any treatment. CO-HFD or LA significantly up-regulated Fas levels in both LVs and cultured cardiomyocytes in a ROS dependent mechanism and independent of modulating intracellular Ca²⁺ levels or calcineurin activity. T1DM or hyperglycemia significant up-regulated mRNA and protein levels of Fas and FasL by activating Ca²⁺/calcineurin/NFAT-4 axis. Furthermore, Fas/FasL cell death induced by recombinant FasL (rFasL) or HG media was enhanced by pre-incubating the cells with LA. In conclusion, activation of the Ca²⁺/calcineurin/NFAT4 axis is indispensable for hyperglycemia-induced Fas/FasL cell death in the cardiomyocytes and CO-HFD sensitizes this by up-regulation of Fas.

Intracoronary Gene Delivery of the Cytoprotective Factor Vascular Endothelial Growth Factor-B167 in Canine Patients with Dilated Cardiomyopathy: A Short-Term Feasibility Study

Dilated cardiomyopathy (DCM) is a myocardial disease of dogs and humans characterized by progressive ventricular dilation and depressed contractility and it is a frequent cause of heart failure. Conventional pharmacological therapy cannot reverse the progression of the disease and, in humans, cardiac transplantation remains the only option during the final stages of heart failure. Cytoprotective gene therapy with vascular endothelial growth factor-B₁₆₇ (VEGF-B₁₆₇) has proved an effective alternative therapy, halting the progression of the disease in experimental studies on dogs. The aim of this work was to test the tolerability and feasibility of intracoronary administration, under fluoroscopic guidance, of VEGF-B₁₆₇ carried by adeno-associated viral vectors in canine DCM patients. Ten patients underwent the gene delivery procedure. The intraoperative phase was well tolerated by all dogs. Clinical and echocardiographic assessments at 7- and 30-days post-procedure showed stable conditions compared to the pre-procedure phase. The results of this work indicate that intracoronary VEGF-B₁₆₇ gene delivery is feasible and tolerated in dogs with DCM. Further monitoring/investigations are ongoing to evaluate the effects of this therapy on disease progression.

Vagus nerve stimulation for the treatment of heart failure

Heart failure (HF) is one of the most prevalent cardiovascular diseases and is associated with high morbidity and mortality. Mechanistically, HF is characterized by an overactive sympathetic nervous system and parasympathetic withdrawal, and this autonomic imbalance contributes to the progression of the disease. As such, modulation of autonomic nervous system by device-based therapy is an attractive treatment target. In this review, we discuss the role of autonomic nervous system dysfunction in the pathogenesis of HF and present the available evidence regarding vagus nerve stimulation for HF, with special emphasis on optimization of stimulation parameters. Finally, we discuss future avenues of research for neuromodulation in patients with HF.

Metformin Protects the Heart Against Hypertrophic and Apoptotic Remodeling After Myocardial Infarction

Cardiovascular complications are the most prevalent cause of morbidity and mortality in diabetic patients. Metformin is currently the first-line blood glucose-lowering agent with potential relevance to cardiovascular diseases. However, the underpinning mechanisms of action remain elusive. Here, we report that metformin represses cardiac apoptosis at least in part through inhibition of Forkhead box O1 (FoxO1) pathway. In a mouse model of ischemia-reperfusion (I/R), treatment with metformin attenuated cardiac and hypertrophic remodeling after 14 days of post-reperfusion. Additionally, cardiac expression of brain-like natriuretic peptide (BNP) was significantly reduced in metformin-treated mice after 14 days of cardiac I/R. In cultured H9C2 cells, metformin counteracted hypertrophic and apoptotic responses to metabolic or hypoxic stress. FoxO1 silencing by siRNA abolished anti-apoptotic effect of metformin under hypoxic stress in H9C2 cells. Taken together, these results suggest that metformin protects the heart against hypertrophic and apoptotic remodeling after myocardial infarction.

Autophagy and Oncosis/Necroptosis Are Enhanced in Cardiomyocytes from Heart Failure Patients

Background

Although originally described as a survival mechanism, it is unknown whether and to what extent autophagy is implicated in the terminal stages of heart failure. Here, we studied magnitude and evolution of autophagy in patients with intractable heart failure.

Material/Methods

Myocardial samples were obtained from 22 patients with ischemic cardiomyopathy and idiopathic dilated cardiomyopathy who were undergoing cardiac transplantation. Hearts from 11 patients who died from non-cardiac causes were used as control samples. Autophagy was evaluated by immunostaining with a monoclonal microtubule associated protein light chain 3 (LC3)-II antibody, while the relationship of autophagy with apoptosis and oncosis was assessed by double staining with TUNEL (terminal deoxynucleotidyl transferase – mediated deoxyuridine triphosphate nick end labeling) assay and complement 9 (C9) immunological staining, respectively. In addition, several necroptotic markers, including RIP1 and RIP3 (receptor interacting protein kinase 1 and 3), anti-C3 (cleaved-caspase-3), and anti-NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) were assessed by immunohistochemistry.

Results

Anti-LC3-II staining was detected in 8.7±1.6% of the heart failure patient heart samples and in 1.2±0.3% of control patient heart samples. Vacuole formation started at one nuclear pole, before becoming bipolar and involving the cytosol. Subsequently, the autophagic process extended also to the nuclei, which underwent a progressive vacuolization and disintegration, assuming a peculiar “strawberry like appearance”. Myocytes with extensive vacuole formation exhibited nuclear degeneration, which was associated with TUNEL, C3, C9, RIP1, and RIP3 positive staining. Conversely, myocytes with less extensive vacuole formation showed RIP1 and NF-κB positive staining, though not positivity for other cell death markers.

Conclusions

Autophagy was extensively detected in end-stage heart failure and its progression, resulted in secondary cell death, with occurrence of oncosis and necroptosis exceeding that of apoptosis. Conversely, activation of the RIP1/NF-κB pathway was associated with cell survival.

Elevated High-Sensitivity Troponin I in the Stabilized Phase after an Acute Coronary Syndrome Predicts All-Cause and Cardiovascular Mortality in a Highly Admixed Population: A 7-Year Cohort

Background

High-sensitivity cardiac troponin I (hs-cTnI) has played an important role in the risk stratification of patients during the in-hospital phase of acute coronary syndrome (ACS), but few studies have determined its role as a long-term prognostic marker in the outpatient setting.

Objective

To investigate the association between levels of hs-cTnI measured in the subacute phase after an ACS event and long-term prognosis in a highly admixed population.

Methods

We measured levels of hs-cTnI in 525 patients 25 to 90 days after admission for an ACS event; these patients were then divided into tertiles according to hs-cTnI levels and followed for up to 7 years. We compared all-cause and cardiovascular mortality using Cox proportional hazards models and adopting a significance level of 5%.

Results

After a median follow-up of 51 months, patients in the highest tertile had a greater hazard ratio (HR) for all-cause mortality after adjustment for age, sex, known cardiovascular risk factors, medication use, and demographic factors (HR: 3.84, 95% CI: 1.92-8.12). These findings persisted after further adjustment for estimated glomerular filtration rate < 60 ml/min/1.73 m² and left ventricular ejection fraction < 0.40 (HR: 6.53, 95% CI: 2.12-20.14). Cardiovascular mortality was significantly higher in the highest tertile after adjustment for age and sex (HR: 5.65, 95% CI: 1.94-16.47) and both in the first (HR: 4.90, 95% CI: 1.35-17.82) and second models of multivariate adjustment (HR: 5.89, 95% CI: 1.08-32.27).

Conclusions

Elevated hs-cTnI levels measured in the stabilized phase after an ACS event are independent predictors of all-cause and cardiovascular mortality in a highly admixed population.

Innate immune response in the pathogenesis of heart failure in survivors of myocardial infarction

Among the different cardiovascular disease complications, atherosclerosis-induced myocardial infarction (MI) is the major contributor of heart failure (HF) and loss of life. This review presents short- and long-term features of post-MI in human hearts and animal models. It is known that the heart does not regenerate, and thus loss of cardiac cells after an MI event is permanent. In survivors of a heart attack, multiple neurohumoral adjustments as well as simultaneous remodeling in both infarcted and noninfarcted regions of the heart help sustain pump function post-MI. In the early phase, migration of inflammatory cells to the infarcted area helps repair and remove the cell debris, while apoptosis results in the elimination of damaged cardiomyocytes, and there is an increase in the antioxidant response to protect the survived myocardium against oxidative stress (OS) injury. However, in the late phase, it appears that there is a relative increase in OS and activation of the innate inflammatory response in cardiomyocytes without any obvious inflammatory cells. In this late stage in survivors of MI, a progressive slow activation of these processes leads to apoptosis, fibrosis, cardiac dysfunction, and HF. Thus, this second phase of an increase in OS, innate inflammatory response, and apoptosis results in wall thinning, dilatation, and consequently HF. It is important to note that this inflammatory response appears to be innate to cardiomyocytes. Blunting of this innate immune cardiomyocyte response may offer new hope for the management of HF.

A novel model of reno-cardiac syndrome in the C57BL/ 6 mouse strain

Background

The end stage renal disease population has a 20 fold higher incidence of cardiovascular mortality compared to the overall population. The development of reno-cardiac syndrome in these patients will result in cardiovascular events to be the cause of 50% of fatalities. There is therefore a need to research improved therapeutic strategies to combat renal cardiac pathologies. Murine in vivo models contribute greatly to such research allowing for specific genetic modification and reduced miscellany, however there is currently no reliable model of reno-cardiac syndrome in the most common genetically modified mouse strain, the C57BL/6. In this study we have manipulated an established model of chronic renal disease using adenine infused diet and prolonged the course of its pathology achieving chronic renal failure and subsequent reno-cardiac syndrome in the C57BL/6 mouse.

Methods

Eight week-old male C57BL/ 6 mice were acclimatised for 7 days before administration of a 0.15% adenine diet or control diet for 20 weeks.

Cardiac function was assessed in mice at week 20 by echocardiography. At experiment termination blood and urine samples were analysed biochemically and organ dysfunction/injury was determined using immunoblotting and immunohistochemistry.

Results

Administration of 0.15% adenine diet caused progressive renal failure resulting in reno-cardiac syndrome. At endpoint uraemia was confirmed by blood biochemistry which in the adenine fed mice showed significant increases in serum creatinine, urea, calcium (P < 0.0001) potassium (P < 0.05), and a significantly reduced glomerular filtration rate (P < 0.05). Reno-cardiac syndrome was confirmed by a significantly increased heart to body weight ratio (P < 0.0001) and echocardiography which showed significant reductions in percentage of ejection fraction, fractional shortening, fractional area change, (P < 0.0001) and an increase in left ventricular end diastolic volume (P < 0.05). Immunoblotting of kidney and heart tissue showed increased apoptosis (caspase 3) and fibrosis (fibronectin) and increases in the cardiac levels of phosphorylated Akt, and renal total Akt. Immunohistochemistry for α-SMA, collagen 1 and collagen 3 further confirmed fibrosis.

Conclusions

We present a novel regimen of adenine diet which induces both chronic kidney disease and reno-cardiac syndrome in the C57/BL6 mouse strain. The non-surgical nature of this model makes it highly reproducible compared to other models currently available.

Electronic supplementary material

The online version of this article (10.1186/s12882-018-1155-3) contains supplementary material, which is available to authorized users.

Gene Therapy for Heart Failure: New Perspectives

PURPOSE OF REVIEW

The current knowledge of pathophysiological and molecular mechanisms responsible for the genesis and development of heart failure (HF) is absolutely vast. Nonetheless, the hiatus between experimental findings and therapeutic options remains too deep, while the available pharmacological treatments are mostly seasoned and display limited efficacy. The necessity to identify new, non-pharmacological strategies to target molecular alterations led investigators, already many years ago, to propose gene therapy for HF. Here, we will review some of the strategies proposed over the past years to target major pathogenic mechanisms/factors responsible for severe cardiac injury developing into HF and will provide arguments in favor of the necessity to keep alive research on this topic.

RECENT FINDINGS

After decades of preclinical research and phases of enthusiasm and disappointment, clinical trials were finally launched in recent years. The first one to reach phase II and testing gene delivery of sarcoendoplasmic reticulum calcium ATPase did not yield encouraging results; however, other trials are ongoing, more efficient viral vectors are being developed, and promising new potential targets have been identified. For instance, recent research is focused on gene repair, in vivo, to treat heritable forms of HF, while strong experimental evidence indicates that specific microRNAs can be delivered to post-ischemic hearts to induce regeneration, a result that was previously thought possible only by using stem cell therapy. Gene therapy for HF is aging, but exciting perspectives are still very open.

Protein Kinase A as a Promising Target for Heart Failure Drug Development

Heart failure (HF) is a clinical syndrome characterized by impaired ability of the heart to fill or eject blood. HF is rather prevalent and it represents the foremost reason of hospitalization in the United States. The costs linked to HF overrun those of all other causes of disabilities, and death in the United States and all over the developed as well as the developing countries which amplify the supreme significance of its prevention. Protein kinase (PK) A plays multiple roles in heart functions including, contraction, metabolism, ion fluxes, and gene transcription. Altered PKA activity is likely to cause the progression to cardiomyopathy and HF. Thus, this review is intended to focus on the roles of PKA and PKA-mediated signal transduction in the healthy heart as well as during the development of HF. Furthermore, the impact of cardiac PKA inhibition/activation will be highlighted to identify PKA as a potential target for the HF drug development.

Persistently elevated plasma heart-type fatty acid binding protein concentration is related with poor outcome in acute decompensated heart failure patients

BACKGROUND

The aim of the study was to determine clinical and prognostic role of repeated heart-type fatty acid binding protein (hFABP) measurements in acute decompensated HF (ADHF) patients.

METHODS

In seventy-seven ADHF patients (III and IV NYHA class, mean age 70 ± 12.7 years, mean left ventricle ejection fraction [LVEF] 29.73 ± 13.3%) plasma hFABPs concentrations (SunRed Biological Technology) were measured twice - on admission and at discharge (mean time of hospitalization 10.7 ± 4.9 days). Combined end point (CEP), assessed after mean 9.2 ± 7.3 months, was defined as death or the need of HF re-hospitalization.

RESULTS

Median hFABP concentration on admission was significantly lower than at discharge. hFABP concentrations on admission significantly correlated with echocardiographic parameters of LV remodeling. Among fifty-six patients (72.7%) who reached CEP, significantly higher admission and discharge hFABP concentrations were found. Patients with plasma discharge hFABP concentrations higher than 7.8 ng/mL were at higher risk of CEP (log-rank test, p = 0.01). Logistic stepwise regression analysis revealed discharge hFABP, LVEF and left ventricle mass index independent and significant predictors of CEP (p < 0.05).

CONCLUSIONS

In ADHF patients plasma hFABP admission concentrations are related with LV remodeling. Persistently elevated hFABP concentrations have prognostic value, as may reflect continuous myocardial damage despite effective treatment and clinical improvement.

Quantitative temporal analysis of protein dynamics in cardiac remodeling

Cardiac remodeling (CR) is a complex dynamic process common to many heart diseases. CR is characterized as a temporal progression of global adaptive and maladaptive perturbations. The complex nature of this process clouds a comprehensive understanding of CR, but greater insight into the processes and mechanisms has potential to identify new therapeutic targets. To provide a deeper understanding of this important cardiac process, we applied a new proteomic technique, PALM (Pulse Azidohomoalanine in Mammals), to quantitate the newly-synthesized protein (NSP) changes during the progression of isoproterenol (ISO)-induced CR in the mouse left ventricle. This analysis revealed a complex combination of adaptive and maladaptive alterations at acute and prolonged time points including the identification of proteins not previously associated with CR. We also combined the PALM dataset with our published protein turnover rate dataset to identify putative biochemical mechanisms underlying CR. The novel integration of analyzing NSPs together with their protein turnover rates demonstrated that alterations in specific biological pathways (e.g., inflammation and oxidative stress) are produced by differential regulation of protein synthesis and degradation.

Cardiomyocyte renewal in the human heart: insights from the fall-out

The capacity of the mammalian heart to regenerate cardiomyocytes has been debated over the last decades. However, limitations in existing techniques to track and identify nascent cardiomyocytes have often led to inconsistent results. Radiocarbon (14C) birth dating, in combination with other quantitative strategies, allows to establish the number and age of human cardiomyocytes, making it possible to describe their age distribution and turnover dynamics. Accurate estimates of cardiomyocyte generation in the adult heart can provide the foundation for novel regenerative strategies that aim to stimulate cardiomyocyte renewal in various cardiac pathologies.

Exercise induces new cardiomyocyte generation in the adult mammalian heart

Loss of cardiomyocytes is a major cause of heart failure, and while the adult heart has a limited capacity for cardiomyogenesis, little is known about what regulates this ability or whether it can be effectively harnessed. Here we show that 8 weeks of running exercise increase birth of new cardiomyocytes in adult mice (~4.6-fold). New cardiomyocytes are identified based on incorporation of ¹⁵N-thymidine by multi-isotope imaging mass spectrometry (MIMS) and on being mononucleate/diploid. Furthermore, we demonstrate that exercise after myocardial infarction induces a robust cardiomyogenic response in an extended border zone of the infarcted area. Inhibition of miR-222, a microRNA increased by exercise in both animal models and humans, completely blocks the cardiomyogenic exercise response. These findings demonstrate that cardiomyogenesis can be activated by exercise in the normal and injured adult mouse heart and suggest that stimulation of endogenous cardiomyocyte generation could contribute to the benefits of exercise.

The adult mammalian heart has a limited cardiomyogenic capacity. Here the authors show that intensive exercise leads to a 4.6-fold increase in murine cardiomyocyte proliferation requiring the expression of miR-222, and that exercise induces an extended cardiomyogenic response in the murine heart after infarction.

Redefining the role of biomarkers in heart failure trials: expert consensus document

Heart failure is a growing cardiovascular disease with significant epidemiological, clinical, and societal implications and represents a high unmet need. Strong efforts are currently underway by academic and industrial researchers to develop novel treatments for heart failure. Biomarkers play an important role in patient selection and monitoring in drug trials and in clinical management. The present review gives an overview of the role of available molecular, imaging, and device-derived digital biomarkers in heart failure drug development and highlights capabilities and limitations of biomarker use in this context.

Short telomeres - A hallmark of heritable cardiomyopathies

Cardiovascular diseases are the leading cause of death worldwide and the incidence increases with age. Genetic testing has taught us much about the pathogenic pathways that drive heritable cardiomyopathies. Here we discuss an unexpected link between shortened telomeres, a molecular marker of aging, and genetic cardiomyopathy. Positioned at the ends of chromosomes, telomeres are DNA repeats which serve as protective caps that shorten with each cell division in proliferative tissues. Cardiomyocytes are an anomaly, as they are largely non-proliferative post-birth and retain relatively stable telomere lengths throughout life in healthy individuals. However, there is mounting evidence that in disease states, cardiomyocyte telomeres significantly shorten. Moreover, this shortening may play an active role in the development of mitochondrial dysfunction central to the etiology of dilated and hypertrophic cardiomyopathies. Elucidation of the mechanisms that underlie the telomere-mitochondrial signaling axis in the heart will provide fresh insights into our understanding of genetic cardiomyopathies, and could lead to the identification of previously uncharacterized modes of therapeutic intervention.

Serum Exosomes Attenuate H2O2-Induced Apoptosis in Rat H9C2 Cardiomyocytes via ERK1/2

Exosomes are small-sized vesicles that can be released from cells into the serum. Exosomes play important roles in regulating many biological processes including cell proliferation, apoptosis, cell cycle, and metabolism. However, the roles and mechanisms of plasma exosomes in the apoptosis of rat H9C2 cardiomyocytes are largely unknown. In this study, we isolated plasma exosomes as confirmed by the marker protein CD63. Using flow cytometry and western blot analysis, we found that exosomes attenuated hydrogen peroxide (H₂O₂)-induced apoptosis and improved survival of rat H9C2 cardiomyocytes. Furthermore, the anti-apoptosis effects of serum exosomes in rat H9C2 cardiomyocytes were mediated by the activation of ERK1/2 signaling pathway. These data indicated that plasma exosomes had the protective effects against cardiomyocyte apoptosis and might be a novel therapy strategy for myocardial injury.

Regulation of BECN1-mediated autophagy by HSPB6: Insights from a human HSPB6S10F mutant

HSPB6/Hsp20 (heat shock protein family B [small] member 6) has emerged as a novel cardioprotector against stress-induced injury. We identified a human mutant of HSPB6 (HSPB6^S10F) exclusively present in dilated cardiomyopathy (DCM) patients. Cardiac expression of this mutant in mouse hearts resulted in remodeling and dysfunction, which progressed to heart failure and early death. These detrimental effects were associated with reduced interaction of mutant HSPB6^S10F with BECN1/Beclin 1, leading to BECN1 ubiquitination and its proteosomal degradation. As a result, autophagy flux was substantially inhibited and apoptosis was increased in HSPB6^S10F-mutant hearts. In contrast, overexpression of wild-type HSPB6 (HSPB6 WT) not only increased BECN1 levels, but also competitively suppressed binding of BECN1 to BCL2, resulting in stimulated autophagy. Indeed, preinhibition of autophagy attenuated the cardioprotective effects of HSPB6 WT. Taken together, these findings reveal a new regulatory mechanism of HSPB6 in cell survival through its interaction with BECN1. Furthermore, Ser10 appears to be crucial for the protective effects of HSPB6 and transversion of this amino acid to Phe contributes to cardiomyopathy.

Role of noncoding RNAs in regulation of cardiac cell death and cardiovascular diseases

Loss of functional cardiomyocytes is a major underlying mechanism for myocardial remodeling and heart diseases, due to the limited regenerative capacity of adult myocardium. Apoptosis, programmed necrosis, and autophagy contribute to loss of cardiac myocytes that control the balance of cardiac cell death and cell survival through multiple intricate signaling pathways. In recent years, non-coding RNAs (ncRNAs) have received much attention to uncover their roles in cell death of cardiovascular diseases, such as myocardial infarction, cardiac hypertrophy, and heart failure. In addition, based on the view that mitochondrial morphology is linked to three types of cell death, ncRNAs are able to regulate mitochondrial fission/fusion of cardiomyocytes by targeting genes involved in cell death pathways. This review focuses on recent progress regarding the complex relationship between apoptosis/necrosis/autophagy and ncRNAs in the context of myocardial cell death in response to stress. This review also provides insight into the treatment for heart diseases that will guide novel therapies in the future.

Inflammation and repair in the ischaemic myocardium

Shortly after myocardial infarction, various circulating leukocyte subsets accumulate in the heart. Leukocyte recruitment is highly coordinated and relies on cell production in the bone marrow, mobilization to the blood, and chemokine-mediated infiltration to the destination tissue. Neutrophils, which are phagocytic and inflammatory, are among the first leukocytes to accumulate in large numbers. Within a day, neutrophils disappear and are replaced by a subset of monocytes that further contribute to inflammation and phagocytosis. After a few days, monocyte-derived reparative macrophages accrue, quell inflammation, and foster angiogenesis and tissue remodelling. Studies suggest a wellbalanced response comprising these three waves is essential to optimal infarct healing.

The spectrum of myocardial homeostasis mechanisms in the settings of cardiac surgery procedures (Review)

Classic cardiac surgery, determined through the function of cardiopulmonary bypass machine and myocardial cardioplegic arrest, represents the most controlled scenario for cardiomyocyte homeostatic disturbances due to systemic inflammatory response and myocardial reperfusion injury. An increasing number of studies have demonstrated that myocardial cell homeostasis in cardiac surgery procedures is a sequence of molecularly interrelated and overlapping mechanisms in the form of apoptosis, autophagy and necrosis, which are activated by a plethora of induced inflammatory mediators and gene-related signaling pathways. In this study, we outline the molecular mechanisms of the cardiomyocyte adaptive homeostatic process and the associated clinical implications, in the settings of classic cardiac surgery procedures.

Caspase-3/-7-Specific Metabolic Precursor for Bioorthogonal Tracking of Tumor Apoptosis

Apoptosis is one of the most important intracellular events in living cell, which is a programmed cell death interrelated with caspase enzyme activity for maintaining homeostasis in multicellular organisms. Therefore, direct apoptosis imaging of living cells can provide enormous advantages for diagnosis, drug discovery, and therapeutic monitoring in various diseases. However, a method of direct apoptosis imaging has not been fully validated, especially for live cells in in vitro and in vivo. Herein, we developed a new apoptosis imaging technology via a direct visualization of active caspase-3/-7 activity in living cells. For this, we synthesized a caspase-3/-7-specific cleavable peptide (KGDEVD) conjugated triacetylated N-azidoacetyl-D-mannosamine (Apo-S-Ac₃ManNAz), wherein the Apo-S-Ac₃ManNAz can be cleaved by the active caspase-3/-7 in live apoptotic cells and the cleaved Ac₃ManNAz molecules can further generate targetable azido groups (N₃) on the living cell surface. Importantly, the azido groups on the apoptotic tumor cells could be visualized with Cy5.5-conjugated dibenzylcyclooctyne (DBCO-Cy5.5) via bioorthogonal click chemistry in vitro cell culture condition and in vivo tumor-bearing mice. Therefore, our Apo-S-Ac₃ManNAz can be utilized for the further applications in tumor therapy as a monitoring tool for anticancer efficacy and optimization of anticancer new drugs in cell culture system and in tumor-bearing mice.

Effect of Atractylodes macrocephala rhizoma on isoproterenol‑induced ventricular remodeling in rats

Myocardial infarction (MI) is the primary cause of ventricular remodeling (VR). The aim of the present study was to determine the effect of Atractylodis macrocephalae rhizoma (AMR) on VR induced by isoproterenol (ISO) in rats. Male Sprague Dawley rats were randomly divided into the normal control, ISO‑induced and AMR groups. Rats in the ISO‑induced and AMR groups were subcutaneously injected with 85 mg/kg/day ISO for two consecutive days. Compared with the ISO‑induced group, AMR normalized the levels of hemodynamic parameters, markedly attenuated myocardial pathological damage, decreased the level of N‑terminal prohormone of brain natriuretic peptide, and inhibited cardiac hypertrophy and myocardial fibrosis. In addition, AMR inhibited oxidative stress and activation of the rennin‑angiotensin‑aldosterone system (RAAS) when compared with the ISO‑induced group. The results of the present study suggest that AMR may reverse VR via its antioxidative effect and inhibition of RAAS activation.

Heart-type fatty acid-binding protein in cardiovascular disease: A systemic review

Fatty acid-binding proteins, whose clinical applications have been studied, are a family of proteins that reflect tissue injury. Heart-type fatty acid-binding protein (H-FABP) is a marker of ongoing myocardial damage and useful for early diagnosis of acute myocardial infarction (AMI). In the past decade, compared to other cardiac enzymes, H-FABP has shown more promise as an early detection marker for AMI. However, the role of H-FABP is being re-examined due to recent refinement in the search for newer biomarkers, and greater understanding of the role of high-sensitivity troponin. We discuss the current role of H-FABP as an early marker for AMI in the era of high sensitive troponin. H-FABP is highlighted as a prognostic marker for a broad spectrum of fatal diseases, viz., AMI, heart failure, arrhythmia, and pulmonary embolism that could be associated with poor clinical outcomes. Because the cut-off value of what constitutes an abnormal H-FABP potentially differs for each cardiovascular event and depends on the clinical setting, an optimal cut-off value has not been clearly established. Of note, several factors such as age, gender, and cardiovascular risk factors, which affect H-FABP levels need to be considered in this context. In this review, we discuss the clinical applications of H-FABP as a prognostic marker in various clinical settings.

Insights from Second-Line Treatments for Idiopathic Dilated Cardiomyopathy

Background: Dilated cardiomyopathy (DCM) is an independent nosographic entity characterized by left ventricular dilatation and contractile dysfunction leading to heart failure (HF). The idiopathic form of DCM (iDCM) occurs in the absence of coronaropathy or other known causes of DCM. Despite being different from other forms of HF for demographic, clinical, and prognostic features, its current pharmacological treatment does not significantly diverge. Methods: In this study we performed a Pubmed library search for placebo-controlled clinical investigations and a post-hoc analysis recruiting iDCM from 1985 to 2016. We searched for second-line pharmacologic treatments to reconsider drugs for iDCM management and pinpoint pathological mechanisms. Results: We found 33 clinical studies recruiting a total of 3392 patients of various durations and sizes, as well as studies that tested different drug classes (statins, pentoxifylline, inotropes). A metanalysis was unfeasible, although a statistical significance for changes upon treatment for molecular results, morphofunctional parameters, and clinical endpoints was reported. Statins appeared to be beneficial in light of their pleiotropic effects; inotropes might be tolerated more for longer times in iDCM compared to ischemic patients. General anti-inflammatory therapies do not significantly improve outcomes. Metabolic and growth modulation remain appealing fields to be investigated. Conclusions: The evaluation of drug effectiveness based on direct clinical benefit is an inductive method providing evidence-based insights. This backward approach sheds light on putative and underestimated pathologic mechanisms and thus therapeutic targets for iDCM management.

Short‑term vagus nerve stimulation reduces myocardial apoptosis by downregulating microRNA‑205 in rats with chronic heart failure

Previous studies have reported that short-term vagus nerve stimulation (VNS) improves cardiac function in rats with chronic heart failure (CHF). The molecular mechanisms are unclear. The potential effect of microRNA (miR)-205 in apoptosis of short-term VNS was examined. A total of 3 weeks after inducing CHF, the rats were divided into three groups: Sham stimulation in sham operated rats, sham stimulation in CHF rats (CHF-SS), and treated with VNS in CHF rats (CHF-VNS). The right vagus nerve of the neck was stimulated for 72 h in CHF rats with rectangular pulses of 40 msec duration at 1 Hz and 5 V. miR-205 was focused on, which exhibited differential expression in the miRNA microarray analysis of CHF rats, and the effects of VNS on apoptosis were examined. It was verified that the expression level of miR-205 in the CHF-SS group was increased, and the expression was reduced in the CHF-VNS group. Furthermore, mimics or inhibitor of miR-205 was transfected into H9c2 to investigate its function on apoptosis. Baculoviral IAP repeat-containing protein 2 (Birc2) was confirmed a target of miR-205 through a dual luciferase reporter assay and western blotting. It was demonstrated that downregulated miR-205 decreased apoptosis in H9c2 cells. The apoptosis-associated proteins were further detected in H9c2 cells and rat tissue. The mRNA and protein expression levels of caspase-3 and Bcl-2-associated X protein were decreased in the CHF-VNS group, the expression of Birc2 and B-cell lymphoma 2 were increased. The results were consistent with the in vitro study in the miR-205 inhibitor group. The present study demonstrated that short-term VNS decreased apoptosis by downregulating miR-205 in rats with CHF. Therefore, the results of the present study provide basic evidence for short-term VNS in the clinical treatment of CHF.

miR-23a Regulates Cardiomyocyte Apoptosis by Targeting Manganese Superoxide Dismutase

Cardiomyocyte apoptosis is initiated by various cellular insults and accumulated cardiomyocyte apoptosis leads to the pathogenesis of heart failure. Excessive reactive oxygen species (ROS) provoke apoptotic cascades. Manganese superoxide dismutase (MnSOD) is an important antioxidant enzyme that converts cellular ROS into harmless products. In this study, we demonstrate that MnSOD is down-regulated upon hydrogen peroxide treatment or ischemia/reperfusion (I/R) injury. Enhanced expression of MnSOD attenuates cardiomyocyte apoptosis and myocardial infarction induced by I/R injury. Further, we show that miR-23a directly regulates the expression of MnSOD. miR-23a regulates cardiomyocyte apoptosis by suppressing the expression of MnSOD. Our study reveals a novel model regulating cardiomyocyte apoptosis which is composed of miR-23a and MnSOD. Our study provides a new method to tackling apoptosis related cardiac diseases.

MDG‑1 inhibits H2O2‑induced apoptosis and inflammation in human umbilical vein endothelial cells

MDG‑1, a water‑soluble polysaccharide extracted from Ophiopogon japonicus, has been reported to serve a role in antimyocardial ischemia by protecting cardiomyocytes from hypoxia/reoxygenation‑induced damage. However, it remains unknown whether MDG‑1 protects human umbilical vein endothelial cells (HUVECs) against oxidative stress‑induced damage. In the present study, HUVECs were treated with hydrogen peroxide (H2O2) to establish an oxidative stress‑induced cell injury model. Treatment of HUVECs with different concentrations of H2O2 significantly attenuated cell viability and increased cell apoptosis in a time and dose‑dependent manner. Pretreatment with MDG‑1 markedly reduced H2O2‑induced cell death, ROS generation and inflammatory factor secretion. In addition, pretreatment with MDG‑1 decreased the expression levels of proapoptotic proteins BCL2 associated X (Bax) and caspase‑3, while it increased the expression levels of the antiapoptotic protein BCL2 apoptosis regulator (Bcl‑2), compared with H2O2 treatment alone. Taken together, the present data suggest that MDG‑1 protected HUVECs against H2O2‑induced apoptosis and inflammation through inhibition of Bax/Bcl‑2 protein ratio, caspase‑3 expression, and inflammatory factor secretion. This study provides a potential application for MDG‑1 in the treatment of cardiovascular disease.

Platycodon grandiflorum (PG) reverses angiotensin II-induced apoptosis by repressing IGF-IIR expression

ETHNOPHARMACOLOGICAL RELEVANCE

Platycodon grandiflorum (PG) is a Chinese medical plant used for decades as a traditional prescription to eliminate phlegm, relieve cough, reduce inflammation and lower blood pressure. PG also has a significant effect on the cardiovascular systems.

MATERIALS AND METHODS

The aqueous extract of Platycodon grandiflorum (JACQ.) A. DC. root was screened for inhibiting Ang II-induced IGF-IIR activation and apoptosis pathway in H9c2 cardiomyocytes. The effects were also studied in spontaneously hypertensive rats (five groups, n=5) using low and high doses of PG for 50 days. The Ang II-induced IGF-IIR activation was analyzed by luciferase reporter, RT-PCR, western blot and surface IGF-IIR expression assay. Furthermore, the major active constituent of PG was carried out by high performance liquid chromatography-mass spectrometry (HPLC-MS).

RESULTS

Our results indicate that a crude extract of PG significantly suppresses the Ang II-induced IGF-IIR signaling pathway to prevent cardiomyocyte apoptosis. PG extract inhibits Ang II-mediated JNK activation and SIRT1 degradation to reduce IGF-IIR activity. Moreover, PG maintains SIRT1 stability to enhance HSF1-mediated IGF-IIR suppression, which prevents cardiomyocyte apoptosis. In animal models, the administration of PG markedly reduced this apoptotic pathway in the heart of SHRs.

CONCLUSION

Taken together, PG may be considered as an effective treatment for cardiac diseases in hypertensive patients.

Extracellular matrix protein laminin enhances mesenchymal stem cell (MSC) paracrine function through αvβ3/CD61 integrin to reduce cardiomyocyte apoptosis

Myocardial ischaemia (MI) results in extensive cardiomyocyte death and reactive oxygen species (ROS)-induced damage in an organ with little or no regenerative capacity. Although the use of adult bone marrow mesenchymal stem cells (BMMSCs) has been proposed as a treatment option, the high cell numbers required for clinical use are difficult to achieve with this source of MSCs, and animal studies have produced inconsistent data. We recently demonstrated in small and large animal models of acute MI that the application of human term placenta-derived multipotent cells (PDMCs), a foetal-stage MSC, resulted in reversal of cardiac injury with therapeutic efficacy. However, the mechanisms involved are unclear, making it difficult to strategize for therapeutic improvements. We found that PDMCs significantly reduced cardiomyocyte apoptosis and ROS production through the paracrine factors GRO-α, HGF and IL-8. Moreover, culturing PDMCs on plates coated with laminin, an extracellular matrix (ECM) protein, resulted in significantly enhanced secretion of all three paracrine factors, which further reduced cardiomyocyte apoptosis. The enhancement of PDMC paracrine function by laminin was mediated through αvβ3 integrin, with involvement of the signalling pathways of JNK, for GRO-α and IL-8 secretion, and PI3K/AKT, for HGF secretion. Our results demonstrated the utility of PDMC therapy to reduce cardiomyocyte apoptosis through modulation of ECM proteins in in vitro culture systems as a strategy to enhance the therapeutic functions of stem cells.

Circulating microRNA-150-5p as a novel biomarker for advanced heart failure: A genome-wide prospective study

BACKGROUND

Circulating microRNAs (miRs) are promising biomarkers for heart failure (HF). Previous studies have provided inconsistent miR "signatures." The phenotypic and pathophysiologic heterogeneity of HF may have contributed to this inconsistency. In this study we assessed whether advanced HF (AHF) patients present a distinct miR signature compared with healthy subjects (HS) and mild to moderate HF (MHF) patients.

METHODS

The study consisted of 2 phases: a screening phase and a validation phase. In the screening phase, 752 miRs were profiled in HS and MHF and AHF patients (N = 15), using the real-time quantitative polymerase chain reaction (RT-qPCR) technique and global mean normalization. In the validation phase, the miRs found to be significantly dysregulated in AHF patients compared with both HS and MHF patients were validated in 15 HS, 25 patients with MHF and 29 with AHF, using RT-qPCR, and normalizing to exogenous (cel-miR-39) and endogenous controls.

RESULTS

In the screening phase, 5 miRs were found to be significantly dysregulated: -26a-5p; -145-3p; -150-5p; -485-3p; and -487b-3p. In the validation phase, miR-150-5p was confirmed to be significantly downregulated in AHF patients when compared with both HS and MHF patients, irrespective of the normalization method used. miR-26a-5p was confirmed to be significantly dysregulated only when normalized to cell-miR-39. Dysregulation of the other miRs could not be confirmed. miR-150-5p was significantly associated with maladaptive remodeling, disease severity and outcome.

CONCLUSIONS

Our data suggest miR-150-5p as a novel circulating biomarker for AHF. The association of miR-150-5p with maladaptive remodeling, disease severity and outcome supports the pathophysiologic relevance of downregulated miR-150-5p expression to AHF.

Pericytes and cardiac stem cells: Common features and peculiarities

Clinical data and basic research indicate that the structural and functional alterations that characterize the evolution of cardiac disease towards heart failure may be, at least in part, reversed. This paradigm shift is due to the accumulation of evidence indicating that, in peculiar settings, cardiomyocytes may be replenished. Moving from the consideration that cardiomyocytes are rapidly withdrawn from the cell cycle after birth, independent laboratories have tested the hypothesis that cardiac resident stem/progenitor cells resided in mammalian hearts and were important for myocardial repair. After almost two decades of intensive investigation, several (but partially overlapping) cardiac resident stem/progenitor cell populations have been identified. These primitive cells are characterized by mesenchymal features, unique properties that distinguish them from mesodermal progenitors residing in other tissues, and heterogeneous embryological origins (that include the neural crest and the epicardium). A further layer of complexity is related to the nature, in vivo localization and properties of mesodermal progenitors residing in adult tissues. Intriguingly, these latter, whose possible perivascular pericyte/mural cell origin has been shown, have been identified in human hearts too. However, their exact anatomical localization, pathophysiological role, and their relationship with cardiac stem/progenitor cells are emerging only recently. Therefore, aim of this review is to discuss the different origin, the distinct nature, and the complementary effect of cardiac stem cells and pericytes supporting regenerative strategies based on the combined use of both myogenic and angiogenic factors.