Reversal of cardiac dysfunction after long-term expression of SERCA2a by gene transfer in a pre-clinical model of heart failure

Echocardiographic and hemodynamic assessment for predicting early clinical events in severe acute mitral regurgitation

The diagnostic role of echocardiographic and hemodynamic assessment in acute mitral regurgitation (AMR) remains unclear. The central question of this study was to determine if echocardiographic and hemodynamic parameters can predict early clinical events in AMR. AMR was induced by percutaneously severing the mitral valve chordae tendineae in 39 Yorkshire pigs. Immediately after AMR induction, echocardiographic and hemodynamic exams were performed, and compared between those who died and those who survived within 30-days of the procedure. Echocardiographic indices of MR severity as well as the left atrial pressure showed significant differences between survivors and non-survivors in univariate analysis. Multi-variate logistic regression analysis revealed that echocardiography-derived regurgitant fraction and vena contracta as well as mean left atrial pressure could be used to segment the cohort into survivors and non-survivors. Our study demonstrated, for the first time, that echocardiographic and hemodynamic assessment of AMR provides predictive information on early clinical events in a clinically relevant animal model of AMR.

Use of Adeno-Associated Virus Vector for Cardiac Gene Delivery in Large-Animal Surgical Models of Heart Failure

The advancement of gene therapy-based approaches to treat heart disease represents a need for clinically relevant animal models with characteristics equivalent to human pathologies. Rodent models of cardiac disease do not precisely reproduce heart failure phenotype and molecular defects. This has motivated researchers to use large animals whose heart size and physiological processes more similar and comparable to those of humans. Today, adeno-associated viruses (AAV)-based vectors are undoubtedly among the most promising DNA delivery vehicles. Here, AAV biology and technology are reviewed and discussed in the context of their use and efficacy for cardiac gene delivery in large-animal models of heart failure, using different surgical approaches. The remaining challenges and opportunities for the use of AAV-based vector delivery for gene therapy applications in the clinic are also highlighted.

SERCA control of cell death and survival

Intracellular calcium (Ca²⁺⁾ is a critical coordinator of various aspects of cellular physiology. It is increasingly apparent that changes in cellular Ca²⁺ dynamics contribute to the regulation of normal and pathological signal transduction that controls cell growth and survival. Aberrant perturbations in Ca²⁺ homeostasis have been implicated in a range of pathological conditions, such as cardiovascular diseases, diabetes, tumorigenesis and steatosis hepatitis. Intracellular Ca²⁺ concentrations are therefore tightly regulated by a number of Ca²⁺ handling enzymes, proteins, channels and transporters located in the plasma membrane and in Ca²⁺ storage organelles, which work in concert to fine tune a temporally and spatially precise Ca²⁺ signal. Chief amongst them is the sarco/endoplasmic reticulum (SR/ER) Ca²⁺ ATPase pump (SERCA) which actively re-accumulates released Ca²⁺ back into the SR/ER, therefore maintaining Ca²⁺ homeostasis. There are at least 14 different SERCA isoforms encoded by three ATP2A1-3 genes whose expressions are species- and tissue-specific. Altered SERCA expression and activity results in cellular malignancy and induction of ER stress and ER stress-associated apoptosis. The role of SERCA misregulation in the control of apoptosis in various cell types and disease setting with prospective therapeutic implications is the focus of this review. Ca²⁺ is a double edge sword for both life as well as death, and current experimental evidence supports a model in which Ca²⁺ homeostasis and SERCA activity represent a nodal point that controls cell survival. Pharmacological or genetic targeting of this axis constitutes an incredible therapeutic potential to treat different diseases sharing similar biological disorders.

Cardiac Thyroid Hormone Metabolism and Heart Failure

The heart is a principal target of thyroid hormone, and a reduction of cardiac thyroid hormone signaling is thought to play a role in pathological ventricular remodeling and the development of heart failure. Studies in various rodent models of heart disease have identified increased activity of cardiac type III deiodinase as a possible cause of diminished levels and action of thyroid hormone. Recent data indicate novel mechanisms underlying the induction of this thyroid hormone-degrading enzyme in the heart as well as post-transcriptional regulation of its expression by microRNAs. In addition, the relevance of diminished thyroid hormone signaling for cardiac remodeling is suggested to include miRNA-mediated effects on pathological signaling pathways. These and other recent studies are reviewed and discussed in the context of other processes and factors that have been implicated in the reduction of cardiac thyroid hormone signaling in heart failure.

Status of Therapeutic Gene Transfer to Treat Cardiovascular Disease in Dogs and Cats

Gene therapy is a procedure resulting in the transfer of a gene into an individual's cells to treat a disease. One goal of gene transfer is to express a functional gene when the endogenous gene is inactive. However, because heart failure is a complex disease characterized by multiple abnormalities at the cellular level, an alternate gene delivery approach is to alter myocardial protein levels to improve function. This article discusses background information on gene delivery, including packaging, administration, and a brief discussion of some of the candidate transgenes likely to alter the progression of naturally occurring heart disease in dogs and cats.

Cardiac gene therapy with adeno-associated virus-based vectors

PURPOSE OF REVIEW

Cardiac gene therapy with adeno-associated virus (AAV)-based vectors is emerging as an entirely new platform to treat, or even cure, so far intractable cardiac disorders. This review describes our current knowledge of cardiac AAV gene therapy with a particular focus on the biggest obstacle for the successful translation of cardiac AAV gene therapy into the clinic, namely the efficient delivery of the therapeutic gene to the myocardium.

RECENT FINDINGS

We summarize the significant recent progress that has been made in treating heart failure in preclinically relevant animal models with AAV gene therapy and the recent results of clinical trials with cardiac AAV gene therapy for the treatment of heart failure. We also discuss the benefits and shortcomings of the currently available delivery methods of AAV to the heart. Finally, we describe the current state of identifying novel AAV variants that have enhanced tropism for human cardiomyocytes and that show increased resistance to preexisting neutralizing antibodies.

SUMMARY

Here, we describe the successes and challenges in cardiac AAV gene therapy, a treatment modality that has the potential to transform current treatment approaches for cardiac diseases.

Randomized Clinical Trials of Gene Transfer for Heart Failure with Reduced Ejection Fraction

Despite improvements in drug and device therapy for heart failure, hospitalization rates and mortality have changed little in the past decade. Randomized clinical trials using gene transfer to improve function of the failing heart are the focus of this review. Four randomized clinical trials of gene transfer in heart failure with reduced ejection fraction (HFrEF) have been published. Each enrolled patients with stable symptomatic HFrEF and used either intracoronary delivery of a virus vector or endocardial injection of a plasmid. The initial CUPID trial randomized 14 subjects to placebo and 25 subjects to escalating doses of adeno-associated virus type 1 encoding sarcoplasmic reticulum calcium ATPase (AAV1.SERCA2a). AAV1.SERCA2a was well tolerated, and the high-dose group met a 6 month composite endpoint. In the subsequent CUPID-2 study, 243 subjects received either placebo or the high dose of AAV1.SERCA2a. AAV1.SERCA2a administration, while safe, failed to meet the primary or any secondary endpoints. STOP-HF used plasmid endocardial injection of stromal cell-derived factor-1 to promote stem-cell recruitment. In a 93-subject trial of patients with ischemic etiology heart failure, the primary endpoint (symptoms and 6 min walk distance) failed, but subgroup analyses showed improvements in subjects with the lowest ejection fractions. A fourth trial randomized 14 subjects to placebo and 42 subjects to escalating doses of adenovirus-5 encoding adenylyl cyclase 6 (Ad5.hAC6). There were no safety concerns, and patients in the two highest dose groups (combined) showed improvements in left ventricular function (left ventricular ejection fraction and -dP/dt). The safety data from four randomized clinical trials of gene transfer in patients with symptomatic HFrEF suggest that this approach can be conducted with acceptable risk, despite invasive delivery techniques in a high-risk population. Additional trials are necessary before the approach can be endorsed for clinical practice.

Expression of integrin-linked kinase improves cardiac function in a swine model of myocardial infarction

Previous studies have described the beneficial effects of overexpressing integrin-linked kinase (ILK) after myocardial infarction (MI) in small animal models. However, the effects of ILK in pre-clinical large animals are not known. To move closer to clinical translation, we examined the effects of ILK gene transfer in a swine model of ischemic heart disease. Swine received percutaneous intracoronary injections of adenoviral vector expressing ILK (n=10) or empty ad-null (n=10) in the left anterior descending coronary artery (LAD) following LAD occlusion. Four weeks after transfection, we confirmed that transgene expression was restricted to the infarcted area in the cardiac tissue. Imaging studies demonstrated preserved cardiac function in the ILK group. ILK treatment was associated with reduced infarcted scar size and preserved left ventricular (LV) geometry (LV diameter and LV wall thickness). Enhanced angiogenesis was preserved in the ILK animals, along with reduction of apoptosis. ILK gene therapy improves cardiac remodeling and function in swine following MI associated with increased angiogenesis, reduced apoptosis, and increased cardiomyocyte proliferation with no signs of toxicity. These results may deliver a new approach to treat post-infarct remodeling and subsequent heart failure.

Overexpression of Sarcoendoplasmic Reticulum Calcium ATPase 2a Promotes Cardiac Sympathetic Neurotransmission via Abnormal Endoplasmic Reticulum and Mitochondria Ca2+ Regulation

Supplemental Digital Content is available in the text.

Reduced cardiomyocyte excitation–contraction coupling and downregulation of the SERCA2a (sarcoendoplasmic reticulum calcium ATPase 2a) is associated with heart failure. This has led to viral transgene upregulation of SERCA2a in cardiomyocytes as a treatment. We hypothesized that SERCA2a gene therapy expressed under a similar promiscuous cytomegalovirus promoter could also affect the cardiac sympathetic neural axis and promote sympathoexcitation. Stellate neurons were isolated from 90 to 120 g male, Sprague–Dawley, Wistar Kyoto, and spontaneously hypertensive rats. Neurons were infected with Ad-mCherry or Ad-mCherry-hATP2Aa (SERCA2a). Intracellular Ca²⁺ changes were measured using fura-2AM in response to KCl, caffeine, thapsigargin, and carbonylcyanide-p-trifluoromethoxyphenylhydrazine to mobilize intracellular Ca²⁺ stores. The effect of SERCA2a on neurotransmitter release was measured using [³H]-norepinephrine overflow from 340 to 360 g Sprague–Dawley rat atria in response to right stellate ganglia stimulation. Upregulation of SERCA2a resulted in greater neurotransmitter release in response to stellate stimulation compared with control (empty: 98.7±20.5 cpm, n=7; SERCA: 186.5±28.41 cpm, n=8; P<0.05). In isolated Sprague–Dawley rat stellate neurons, SERCA2a overexpression facilitated greater depolarization-induced Ca²⁺ transients (empty: 0.64±0.03 au, n=57; SERCA: 0.75±0.03 au, n=68; P<0.05), along with increased endoplasmic reticulum and mitochondria Ca²⁺ load. Similar results were observed in Wistar Kyoto and age-matched spontaneously hypertensive rats, despite no further increase in endoplasmic reticulum load being observed in the spontaneously hypertensive rat (spontaneously hypertensive rats: empty, 0.16±0.04 au, n=18; SERCA: 0.17±0.02 au, n=25). In conclusion, SERCA2a upregulation in cardiac sympathetic neurons resulted in increased neurotransmission and increased Ca²⁺ loading into intracellular stores. Whether the increased Ca²⁺ transient and neurotransmission after SERCA2A overexpression contributes to enhanced sympathoexcitation in heart failure patients remains to be determined.

Luteolin improves cardiac dysfunction in heart failure rats by regulating sarcoplasmic reticulum Ca2+-ATPase 2a

We previously found that luteolin (Lut) appeared to improve the contractility of cardiomyocytes during ischemia/reperfusion in rats. The enhancement was associated with the alteration in sarcoplasmic reticulum Ca²⁺-ATPase 2a (SERCA2a). This finding prompted us to consider if the mechanism worked in heart failure (HF). We studied the regulation of SERCA2a by Lut in failing cardiomyocytes and intact heart of rats. Improvement of contractility and the mechanisms centered on SERCA2a were studied in isolated cardiomyocytes and intact heart. We found that Lut significantly improved contractility and Ca²⁺ transients, ameliorated expression, activity and stability of SERCA2a and upregulated expression of small ubiquitin-related modifier (SUMO) 1, which is a newfound SERCA2a regulator. Lut also increased phosphorylation of protein kinase B (Akt), phospholaban (PLB) and sumoylation of SERCA2a, specificity protein 1 (Sp1). Transcriptions of SUMO1 and SERCA2a were concurrently increased. Inhibition of posphatidylinositol 3 kinase/Akt (PI3K/Akt) pathway and SERCA2a activity both markedly abolished Lut-induced benefits in vitro and in vivo. Lut upregulated the expression ratio of Bcl-2/Bax, caspase-3/cleaved-Caspase3. Meanwhile, Lut ameliorated the myocardium fibrosis of HF. These discoveries provide an important potential therapeutic strategy that Lut targeted SERCA2a SUMOylation related to PI3K/Akt-mediated regulations on rescuing the dysfunction of HF.

Current Methods in Cardiac Gene Therapy: Overview

During the last decade, there has been a significant progress toward clinical translation in the field of cardiac gene therapy based on extensive preclinical data. However, despite encouraging positive results in early phase clinical trials, more recent larger trials reported only neutral results. Nevertheless, the field has gained important knowledge from these trials and is leading to the development of more cardiotropic vectors and improved delivery systems. It has become more evident that humans are more resistant to therapeutic transgene expression compared to experimental animals and thus refinement in gene delivery tools and methods are essential for future success. We provide an overview of the current status of cardiac gene therapy focusing on gene delivery tools and methods. Newer technologies, devices, and approaches will undoubtedly lead to more promising clinical results in the near future.

Cardiac Gene Delivery in Large Animal Models: Antegrade Techniques

Percutaneous antegrade coronary injection is among the least invasive cardiac selective gene delivery methods. However, transduction efficiency is quite low with a simple bolus antegrade injection. In order to improve the transduction efficiency using antegrade delivery, several additional approaches have been proposed.In this chapter, we briefly discuss important elements associated with intracoronary delivery methods and present protocols for three different catheter-based antegrade delivery techniques in a preclinical large animal model. Despite the lower transduction efficacy relative to more invasive delivery techniques, antegrade techniques have the advantage of being clinically well established and having safer profiles which is important when treating patients with cardiac disease.

Gene therapy for heart failure

Novel strategies are needed to treat the growing population of heart failure patients. While new drug and device based therapies have improved outcomes over the past several decades, heart failure patients continue to experience amongst the lowest quality of life of any chronic disease, high likelihood of being hospitalized and marked reduction in survival. Better understanding of many of the basic mechanisms involved in the development of heart failure has helped identify abnormalities that could potentially be targeted by gene transfer. Despite success in experimental animal models, translating gene transfer strategies from the laboratory to the clinic remains at an early stage. This review provides an introduction to gene transfer as a therapy for treating heart failure, describes some of the many factors that need to be addressed in order for it to be successful and discusses some of the recent studies that have been carried out in heart failure patients. Insights from these studies highlight both the enormous promise of gene transfer and the obstacles that still need to be overcome for this treatment approach to be successful.

A Decoy Peptide Targeted to Protein Phosphatase 1 Attenuates Degradation of SERCA2a in Vascular Smooth Muscle Cells

Neointimal growth in the injured vasculature is largely facilitated by the proliferation of vascular smooth muscle cells (VSMC), which associates with reduced sarco/endoplasmic reticulum Ca²⁺-ATPase (SERCA2a) activity. The gene transfer-mediated restoration of the SERCA2a level thus attenuates neointimal growth and VSMC proliferation. We previously reported that a peptide targeted to protein phosphatase 1, ψPLB-SE, normalizes SERCA2a activity in cardiomyocytes. In this study, we found that ψPLB-SE attenuated neointimal growth in balloon-injured rat carotid arteries, and the proliferation and migration of VSMC cultured in high-serum media (synthetic conditions). In parallel, ψPLB-SE inhibited the degradation of SERCA2a in the injured carotid arteries and VSMC under synthetic conditions. The calpain inhibitor MDL28170 also attenuated SERCA2a degradation and VSMC proliferation under synthetic conditions, indicating that calpain degrades SERCA2a. The Ca²⁺ ionophore A23187 induced SERCA2a degradation in VSMC, which was blocked by either ψPLB-SE or MDL28170. Additionally, ψPLB-SE normalized the cytosolic Ca²⁺ level in VSMC that was increased by either A23187 or synthetic stimulation. Collectively, these data indicate that ψPLB-SE corrects the abnormal Ca²⁺ handling by activating SERCA2a, which further protects SERCA2a from calpain-dependent degradation in VSMC. We conclude that ψPLB-SE may form the basis of a therapeutic strategy for vascular proliferative disorders.

Spacial and Temporal Patterns of Gene Expression After Cardiac MEK1 Gene Transfer Improve Post-Infarction Remodeling Without Inducing Global Hypertrophy

Alteration of mitogen activated protein (MAP) kinase signaling in transgenic mice can ameliorate post-myocardial infarction (MI) remodeling. However, pre-existing changes in transgenic hearts and clinically unrealistic transgene expression likely affect the response to injury; it is unknown whether clinically relevant induction of transgene expression in an otherwise normal heart can yield similar benefits. Constitutively active MEK1 (aMEK1) or LacZ adeno-associated virus 9 (AAV9) vectors were injected into the left ventricular (LV) chambers of mice either just before or after coronary ligation. Hearts were evaluated via Western blot, quantitative polymerase chain reaction, histology, and echocardiography. AAV9-mediated aMEK1 delivery altered ERK1/2 expression/activation as in transgenic mice. Transgene expression was not immediately detectable but plateaued at 17 days, and therefore did not likely impact acute ischemia as it would in transgenics. With AAV9-aMEK1 injection just prior to MI, robust expression in the infarct border zone during post-MI remodeling increased border zone wall thickness and reduced infarct size versus controls at 4 weeks, but did not induce global hypertrophy. Significant improvements in local and global LV function were observed, as were trends toward a preservation of LV volume. Delivery after ligation significantly lowered transgene expression in the infarct border zone and did not yield structural or functional benefits. The primary benefits observed in transgenic mice, ameliorated remodeling, and reduced chronic infarct size, were achievable via clinically relevant gene transfer of aMEK1, supporting ongoing translational efforts. Important differences, however, were observed, and consideration must be given to the timing and distribution of transgene delivery and expression. J. Cell. Biochem. 118: 775-784, 2017. © 2016 Wiley Periodicals, Inc.

Novel Therapies for Heart Failure - Where Do They Stand?

Despite advances in therapy, patients with heart failure (HF) continue to experience unacceptably high rates of hospitalization and death, as well as poor quality of life. As a consequence, there is an urgent need for new treatments that can improve the clinical course of the growing worldwide population of HF patients. Serelaxin and ularatide, both based on naturally occurring peptides, have potent vasodilatory as well as other effects on the heart and kidneys. For both agents, phase 3 studies that are designed to determine whether they improve outcomes in patients with acute HF have completed enrollment. TRV027, a biased ligand for the type 1 angiotensin receptor with effects that extend beyond traditional angiotensin-receptor blockers is also being studied in the acute HF population. Omecamtiv mecarbil, an inotropic agent that improves myocardial contractility by a novel mechanism, and vericiguat, a drug that stimulates soluble guanylate cyclase, are both being developed to treat patients with chronic HF. Finally, despite the negative results of the CUPID study, gene transfer therapy continues to be explored as a means of improving the function of the failing heart. The basis for the use of these drugs and their current status in clinical trials are discussed. (Circ J 2016; 80: 1882-1891).

Pharmacology of heart failure: From basic science to novel therapies

Chronic heart failure is one of the leading causes for hospitalization in the United States and Europe, and is accompanied by high mortality. Current pharmacological therapy of chronic heart failure with reduced ejection fraction is largely based on compounds that inhibit the detrimental action of the adrenergic and the renin-angiotensin-aldosterone systems on the heart. More than one decade after spironolactone, two novel therapeutic principles have been added to the very recently released guidelines on heart failure therapy: the HCN-channel inhibitor ivabradine and the combined angiotensin and neprilysin inhibitor valsartan/sacubitril. New compounds that are in phase II or III clinical evaluation include novel non-steroidal mineralocorticoid receptor antagonists, guanylate cyclase activators or myosine activators. A variety of novel candidate targets have been identified and the availability of gene transfer has just begun to accelerate translation from basic science to clinical application. This review provides an overview of current pharmacology and pharmacotherapy in chronic heart failure at three stages: the updated clinical guidelines of the American Heart Association and the European Society of Cardiology, new drugs which are in clinical development, and finally innovative drug targets and their mechanisms in heart failure which are emerging from preclinical studies will be discussed.

Review of novel therapeutic targets for improving heart failure treatment based on experimental and clinical studies

Heart failure (HF) is a major public health priority due to its epidemiological transition and the world's aging population. HF is typified by continuous loss of contractile function with reduced, normal, or preserved ejection fraction, elevated vascular resistance, fluid and autonomic imbalance, and ventricular dilatation. Despite considerable advances in the treatment of HF over the past few decades, mortality remains substantial. Pharmacological treatments including β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists have been proven to prolong the survival of patients with HF. However, there are still instances where patients remain symptomatic, despite optimal use of existing therapeutic agents. This understanding that patients with chronic HF progress into advanced stages despite receiving optimal treatment has increased the quest for alternatives, exploring the roles of additional pathways that contribute to the development and progression of HF. Several pharmacological targets associated with pathogenesis of HF have been identified and novel therapies have emerged. In this work, we review recent evidence from proposed mechanisms to the outcomes of experimental and clinical studies of the novel pharmacological agents that have emerged for the treatment of HF.

Robust Lentiviral Gene Delivery But Limited Transduction Capacity of Commonly Used Adeno-Associated Viral Serotypes in Xenotransplanted Human Skin

Skin is an easily accessible organ, and therapeutic gene transfer to skin remains an attractive alternative for the treatment of skin diseases. Although we have previously documented potent lentiviral gene delivery to human skin, vectors based on adeno-associated virus (AAV) rank among the most promising gene delivery tools for in vivo purposes. Thus, we compared the potential usefulness of various serotypes of recombinant AAV vectors and lentiviral vectors for gene transfer to human skin in a xenotransplanted mouse model. Vector constructs encoding firefly luciferase were packaged in AAV capsids of serotype 1, 2, 5, 6, 8, and 9 and separately administered by intradermal injection in human skin transplants. For all serotypes, live bioimaging demonstrated low levels of transgene expression in the human skin graft, and firefly luciferase expression was observed primarily in neighboring tissue outside of the graft. In contrast, gene delivery by intradermally injected lentiviral vectors was efficient and led to extensive and persistent firefly luciferase expression within the human skin graft only. The study demonstrates the limited capacity of single-stranded AAV vectors of six commonly used serotypes for gene delivery to human skin in vivo.

Relaxin-2 improves diastolic function of pressure-overloaded rats via phospholamban by activating Akt

BACKGROUND

Relaxin is a peptide hormone which has been demonstrated to be safe and has a therapeutic effect on acute heart failure in clinic trials. However, its effect on diastolic function is still unknown. The aims of the study were to determine whether relaxin could improve the diastolic function in pressure-overloaded rat model and to analyze potential mechanisms.

METHODS AND RESULTS

In the present study, a pressure-overloaded rat model induced by transaortic constriction (TAC) was established. Four weeks after TAC, echocardiography was performed and then all the rat models were randomly divided into 3 groups: models without intramyocardial injection (TAC), with intramyocardial injection of empty adenoviral vector (TAC+GFP) and adenoviral vector overexpression relaxin-2 gene (TAC+RLN2). A sham group was also included. Twelve days after intramyocardial injection, echocardiography and hemodynamics were carried out to evaluate diastolic function in sham, TAC, TAC+GFP and TAC+RLN2 groups. Then hearts were harvested for subsequent examinations. The results indicated that relaxin-2 had ameliorated diastolic function in the pressure-overloaded rats. Compared with the TAC and TAC+GFP groups, the relaxin-2 gene transfer increased phosphorylation of Akt at both the Ser473 and Thr308 sites. Meanwhile, it increased the Ser16 and Thr17- phosphorylation levels of phospholamban (PLB). Furthermore, SERCA2 activity was enhanced in the TAC+RLN2 group more than in the TAC and TAC+GFP groups.

CONCLUSIONS

These results demonstrated that relaxin-2 gene therapy improved diastolic function in pressure-overloaded rats. The potential mechanism may be that relaxin-2 gene transfer enhances SERCA2 activity in hearts by increasing phospholamban phosphorylation through nuclear-targeted Akt phosphorylation.

Post-translational Modifications in Heart Failure: Small Changes, Big Impact

Heart failure is a complex disease process with various aetiologies and is a significant cause of morbidity and death world-wide. Post-translational modifications (PTMs) alter protein structure and provide functional diversity in terms of physiological functions of the heart. In addition, alterations in protein PTMs have been implicated in human disease pathogenesis. Small ubiquitin-like modifier mediated modification (SUMOylation) pathway was found to play essential roles in cardiac development and function. Abnormal SUMOylation has emerged as a new feature of heart failure pathology. In this review, we will highlight the importance of SUMOylation as a regulatory mechanism of SERCA2a function, and its therapeutic potential for the treatment of heart failure.

Calcium upregulation by percutaneous administration of gene therapy in patients with cardiac disease (CUPID 2): a randomised, multinational, double-blind, placebo-controlled, phase 2b trial

BACKGROUND

Sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA2a) activity is deficient in the failing heart. Correction of this abnormality by gene transfer might improve cardiac function. We aimed to investigate the clinical benefits and safety of gene therapy through infusion of adeno-associated virus 1 (AAV1)/SERCA2a in patients with heart failure and reduced ejection fraction.

METHODS

We did this randomised, multinational, double-blind, placebo-controlled, phase 2b trial at 67 clinical centres and hospitals in the USA, Europe, and Israel. High-risk ambulatory patients with New York Heart Association class II-IV symptoms of heart failure and a left ventricular ejection fraction of 0·35 or less due to an ischaemic or non-ischaemic cause were randomly assigned (1:1), via an interactive voice and web-response system, to receive a single intracoronary infusion of 1 × 10(13) DNase-resistant particles of AAV1/SERCA2a or placebo. Randomisation was stratified by country and by 6 min walk test distance. All patients, physicians, and outcome assessors were masked to treatment assignment. The primary efficacy endpoint was time to recurrent events, defined as hospital admission because of heart failure or ambulatory treatment for worsening heart failure. Primary efficacy endpoint analyses and safety analyses were done by modified intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01643330.

FINDINGS

Between July 9, 2012, and Feb 5, 2014, we randomly assigned 250 patients to receive either AAV1/SERCA2a (n=123) or placebo (n=127); 243 (97%) patients comprised the modified intention-to-treat population. Patients were followed up for at least 12 months; median follow-up was 17·5 months (range 1·8-29·4 months). AAV1/SERCA2a did not improve time to recurrent events compared with placebo (104 vs 128 events; hazard ratio 0·93, 95% CI 0·53-1·65; p=0·81). No safety signals were noted. 20 (16%) patients died in the placebo group and 25 (21%) patients died in the AAV1/SERCA2a group; 18 and 22 deaths, respectively, were adjudicated as being due to cardiovascular causes.

INTERPRETATION

CUPID 2 is the largest gene transfer study done in patients with heart failure so far. Despite promising results from previous studies, AAV1/SERCA2a at the dose tested did not improve the clinical course of patients with heart failure and reduced ejection fraction. Although we did not find evidence of improved outcomes at the dose of AAV1/SERCA2a studied, our findings should stimulate further research into the use of gene therapy to treat patients with heart failure and help inform the design of future gene therapy trials.

FUNDING

Celladon Corporation.

Gene therapy for the treatment of heart failure: promise postponed

Gene therapy has emerged as a powerful tool in targeting the molecular mechanisms implicated in heart failure. Refinements in vector technology, including the development of recombinant adeno-associated vectors, have allowed for safe, long-term, and efficient gene transfer to the myocardium. These advancements, coupled with evolving delivery techniques, have placed gene therapy as a viable therapeutic option for patients with heart failure. However, after much promise in early-phase clinical trials, the more recent larger clinical trials have shown disappointing results, thus forcing the field to re-evaluate current vectors, delivery systems, targets, and endpoints. We provide here an updated review of current cardiac gene therapy programmes that have been or are being translated into clinical trials.

Breast cancer treatment-associated cardiovascular toxicity and effects of exercise countermeasures

Advances in breast cancer treatment have improved disease-free survival and overall survival in women with early-stage breast cancer. However, these improvements may be attenuated by the adverse cardiovascular effects associated with breast cancer adjuvant therapy. Exercise may be a potential strategy to counteract these toxicities. The purpose of this paper is to provide an overview on the adverse cardiovascular effects of breast cancer therapy as well as the evidence supporting the potential cardioprotective effects of exercise training in breast cancer patients during and after treatment. We will also discuss research gaps and avenues for future research.

Myocardial Delivery of Lipidoid Nanoparticle Carrying modRNA Induces Rapid and Transient Expression

Nanoparticle-based delivery of nucleotides offers an alternative to viral vectors for gene therapy. We report highly efficient in vivo delivery of modified mRNA (modRNA) to rat and pig myocardium using formulated lipidoid nanoparticles (FLNP). Direct myocardial injection of FLNP containing 1-10 μg eGFPmodRNA in the rat (n = 3 per group) showed dose-dependent enhanced green fluorescent protein (eGFP) mRNA levels in heart tissue 20 hours after injection, over 60-fold higher than for naked modRNA. Off-target expression, including lung, liver, and spleen, was <10% of that in heart. Expression kinetics after injecting 5 μg FLNP/eGFPmodRNA showed robust expression at 6 hours that reduced by half at 48 hours and was barely detectable at 2 weeks. Intracoronary administration of 10 μg FLNP/eGFPmodRNA also proved successful, although cardiac expression of eGFP mRNA at 20 hours was lower than direct injection, and off-target expression was correspondingly higher. Findings were confirmed in a pilot study in pigs using direct myocardial injection as well as percutaneous intracoronary delivery, in healthy and myocardial infarction models, achieving expression throughout the ventricular wall. Fluorescence microscopy revealed GFP-positive cardiomyocytes in treated hearts. This nanoparticle-enabled approach for highly efficient, rapid and short-term mRNA expression in the heart offers new opportunities to optimize gene therapies for enhancing cardiac function and regeneration.

From Bench to Bedside: New Approaches to Therapeutic Discovery for Heart Failure

Heart failure is a significant global health problem, which is becoming worse as the population ages, and remains one of the biggest burdens on our economy. Despite significant advances in cardiovascular medicine, management and surgery, mortality rates remain high, with almost half of patients with heart failure dying within five years of diagnosis. As a multifactorial clinical syndrome, heart failure still represents an epidemic threat, highlighting the need for deeper insights into disease mechanisms and the development of innovative therapeutic strategies for both treatment and prevention. In this review, we discuss conventional heart failure therapies and highlight new pharmacological agents targeting pathophysiological features of the failing heart, for example, non-coding RNAs, angiotensin receptor-neprilysin inhibitors, cardiac myosin activators, BGP-15 and molecules targeting GRK2 including M119, gallein and paroxetine. Finally, we address the disparity between phase II and phase III clinical trials that prevent the translation of emerging HF therapies into new and approved therapies.

Chronic heart failure: Ca(2+), catabolism, and catastrophic cell death

Robust successes have been achieved in recent years in conquering the acutely lethal manifestations of heart disease. Many patients who previously would have died now survive to enjoy happy and productive lives. Nevertheless, the devastating impact of heart disease continues unabated, as the spectrum of disease has evolved with new manifestations. In light of this ever-evolving challenge, insights that culminate in novel therapeutic targets are urgently needed. Here, we review fundamental mechanisms of heart failure, both with reduced (HFrEF) and preserved (HFpEF) ejection fraction. We discuss pathways that regulate cardiomyocyte remodeling and turnover, focusing on Ca(2+) signaling, autophagy, and apoptosis. In particular, we highlight recent insights pointing to novel connections among these events. We also explore mechanisms whereby potential therapeutic approaches targeting these processes may improve morbidity and mortality in the devastating syndrome of heart failure.

Gene therapy for cardiovascular disease: advances in vector development, targeting, and delivery for clinical translation

Gene therapy is a promising modality for the treatment of inherited and acquired cardiovascular diseases. The identification of the molecular pathways involved in the pathophysiology of heart failure and other associated cardiac diseases led to encouraging preclinical gene therapy studies in small and large animal models. However, the initial clinical results yielded only modest or no improvement in clinical endpoints. The presence of neutralizing antibodies and cellular immune responses directed against the viral vector and/or the gene-modified cells, the insufficient gene expression levels, and the limited gene transduction efficiencies accounted for the overall limited clinical improvements. Nevertheless, further improvements of the gene delivery technology and a better understanding of the underlying biology fostered renewed interest in gene therapy for heart failure. In particular, improved vectors based on emerging cardiotropic serotypes of the adeno-associated viral vector (AAV) are particularly well suited to coax expression of therapeutic genes in the heart. This led to new clinical trials based on the delivery of the sarcoplasmic reticulum Ca²⁺-ATPase protein (SERCA2a). Though the first clinical results were encouraging, a recent Phase IIb trial did not confirm the beneficial clinical outcomes that were initially reported. New approaches based on S100A1 and adenylate cyclase 6 are also being considered for clinical applications. Emerging paradigms based on the use of miRNA regulation or CRISPR/Cas9-based genome engineering open new therapeutic perspectives for treating cardiovascular diseases by gene therapy. Nevertheless, the continuous improvement of cardiac gene delivery is needed to allow the use of safer and more effective vector doses, ultimately bringing gene therapy for heart failure one step closer to reality.

Characterization of regional left ventricular function in nonhuman primates using magnetic resonance imaging biomarkers: a test-retest repeatability and inter-subject variability study

Pre-clinical animal models are important to study the fundamental biological and functional mechanisms involved in the longitudinal evolution of heart failure (HF). Particularly, large animal models, like nonhuman primates (NHPs), that possess greater physiological, biochemical, and phylogenetic similarity to humans are gaining interest. To assess the translatability of these models into human diseases, imaging biomarkers play a significant role in non-invasive phenotyping, prediction of downstream remodeling, and evaluation of novel experimental therapeutics. This paper sheds insight into NHP cardiac function through the quantification of magnetic resonance (MR) imaging biomarkers that comprehensively characterize the spatiotemporal dynamics of left ventricular (LV) systolic pumping and LV diastolic relaxation. MR tagging and phase contrast (PC) imaging were used to quantify NHP cardiac strain and flow. Temporal inter-relationships between rotational mechanics, myocardial strain and LV chamber flow are presented, and functional biomarkers are evaluated through test-retest repeatability and inter subject variability analyses. The temporal trends observed in strain and flow was similar to published data in humans. Our results indicate a dominant dimension based pumping during early systole, followed by a torsion dominant pumping action during late systole. Early diastole is characterized by close to 65% of untwist, the remainder of which likely contributes to efficient filling during atrial kick. Our data reveal that moderate to good intra-subject repeatability was observed for peak strain, strain-rates, E/circumferential strain-rate (CSR) ratio, E/longitudinal strain-rate (LSR) ratio, and deceleration time. The inter-subject variability was high for strain dyssynchrony, diastolic strain-rates, peak torsion and peak untwist rate. We have successfully characterized cardiac function in NHPs using MR imaging. Peak strain, average systolic strain-rate, diastolic E/CSR and E/LSR ratios, and deceleration time were identified as robust biomarkers that could potentially be applied to future pre-clinical drug studies.

Hypoxia-driven sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2) downregulation depends on low-density lipoprotein receptor-related protein 1 (LRP1)-signalling in cardiomyocytes

The maintenance of sarcoplasmic reticulum Ca(2+) ATPase (SERCA2) activity is crucial for cardiac function and SERCA2 is dramatically reduced in the heart exposed to hypoxic/ischemic conditions. Previous work from our group showed that hypoxia upregulates the phosphorylated form of the Ca(2+)-dependent nonreceptor protein tyrosine kinase (PTK) proline-rich tyrosine kinase 2 (pPyk2) protein levels in a low-density lipoprotein receptor-related protein (LRP1)-dependent manner. Pyk2 in turn may modulate SERCA2 in cardiomyocytes although this remains controversial. We therefore aimed to investigate the role of LRP1 on hypoxia-induced SERCA2 depletion in cardiomyocytes and to establish LRP1 signalling mechanisms involved. Western blot analysis showed that hypoxia reduced SERCA2 concomitantly with a sustained increase in LRP1 and pPyk2 protein levels in HL-1 cardiomyocytes. By impairing hypoxia-induced Pyk2 phosphorylation and HIF-1α accumulation, LRP1 deficiency prevented SERCA2 depletion and reduction of the sarcoplasmic reticulum calcium content in cardiomyocytes. Moreover, the inhibition of Pyk2 phosphorylation (with the Src-family inhibitor PP2) or the specific silencing of Pyk2 (with siRNA-anti Pyk2) preserved low HIF-1α and high SERCA2 levels in HL-1 cardiomyocytes exposed to hypoxia. We determined that the LRP1/Pyk2 axis represses SERCA2 mRNA expression via HIF-1α since HIF-1α overexpression abolished the protective effect of LRP1 deficiency on SERCA2 depletion. Our findings show a crucial role of LRP1/Pyk2/HIF-1α in hypoxia-induced cardiomyocyte SERCA2 downregulation, a pathophysiological process closely associated with heart failure.

Ribonucleotide reductase-mediated increase in dATP improves cardiac performance via myosin activation in a large animal model of heart failure

AIMS

Heart failure remains a leading cause of morbidity, hospitalizations, and deaths. We previously showed that overexpression of the enzyme ribonucleotide reductase (RNR) in cardiomyocytes increased levels of the myosin activator, 2-deoxy-ATP, catalysed enhanced contraction, and improved cardiac performance in rodent hearts. Here we used a swine model of myocardial infarction (MI) to test preliminarily a novel gene therapy for heart failure based on delivery of the human RNR enzyme complex under the control of a cardiac-specific promoter via an adeno-associated virus serotype 6 vector--designated as BB-R12.

METHODS AND RESULTS

We induced heart failure following MI in Yucatan minipigs by balloon occlusion of the left anterior descending artery. Two weeks, later, pigs received BB-R12 at one of three doses via antegrade coronary infusion. At 2 months post-treatment, LVEF and systolic LV dimension (measured by echocardiography) improved significantly in the high-dose group, despite further deterioration in the saline controls. Haemodynamic parameters including LV end-diastolic pressure, +dP/dt, and -dP/dt all trended towards improvement in the high-dose group. We observed no difference in the histopathological appearance of hearts or other organs from treated animals vs. controls, nor did we encounter any safety or tolerability concerns following BB-R12 delivery.

CONCLUSION

These pilot results suggest cardiac-specific gene therapy using BB-R12 may reverse cardiac dysfunction by myosin activation in a large-animal heart failure model with no observed safety concerns. Thus further research into the therapeutic potential of BB-R12 for patients with chronic heart failure appears warranted.

Gene therapy for heart failure

Heart failure is a major public health problem throughout the world and it is likely that its prevalence will continue to grow over the next several decades. Despite advances in the treatment of heart failure, morbidity and mortality remain unacceptably high. Gene transfer therapy provides a novel strategy for targeting abnormalities in cardiac cells that adversely affect cardiac function. New vectors for gene delivery, mainly adeno-associated viruses (AAVs) that are preferentially taken up by cardiomyocytes, can result in sustained transgene expression. The cardiac isoform of sarco(endo)plasmic reticulum Ca(2+)ATPase (SERCA2a) plays a major role in regulating calcium levels in cardiomyocytes. Abnormal calcium handling by the failing heart caused by a reduction in SERCA2a activity adversely affects both systolic and diastolic function. The Calcium Upregulation by Percutaneous Administration of Gene Therapy in Cardiac Disease (CUPID) study was a Phase 2a double-blind, randomized, placebo-controlled, dose-finding study that was performed in patients with advanced heart failure due to systolic dysfunction. Eligible patients received AAV/SERCA2a or placebo by direct antegrade infusion into the coronary circulation. At the end of 12 months, patients receiving high-dose therapy (i.e. 1×10(13) DNase Resistant Particles) had evidence of favorable changes in several clinically relevant domains compared to patients treated with placebo. There were no safety concerns at any dose of AAV/SERCA2a. Patients treated with AAV/SERCA2a exhibited a striking reduction in cardiovascular events that persisted through 36 months of follow-up compared to patients who received placebo. Transgene expression was detected in the myocardium of patients receiving AAV/SERCA2a gene therapy as long as 31 months after delivery. A second Phase 2b study, CUPID 2, designed to confirm this favorable effect on heart failure events, is currently underway with the results expected to be presented later in 2015. Additional studies using other vectors and targets are in planning or underway making gene transfer therapy one of the most exciting new approaches under development for treating heart failure.

The war against heart failure: the Lancet lecture

Heart failure is a global problem with an estimated prevalence of 38 million patients worldwide, a number that is increasing with the ageing of the population. It is the most common diagnosis in patients aged 65 years or older admitted to hospital and in high-income nations. Despite some progress, the prognosis of heart failure is worse than that of most cancers. Because of the seriousness of the condition, a declaration of war on five fronts has been proposed for heart failure. Efforts are underway to treat heart failure by enhancing myofilament sensitivity to Ca(2+); transfer of the gene for SERCA2a, the protein that pumps calcium into the sarcoplasmic reticulum of the cardiomyocyte, seems promising in a phase 2 trial. Several other abnormal calcium-handling proteins in the failing heart are candidates for gene therapy; many short, non-coding RNAs--ie, microRNAs (miRNAs)--block gene expression and protein translation. These molecules are crucial to calcium cycling and ventricular hypertrophy. The actions of miRNAs can be blocked by a new class of drugs, antagomirs, some of which have been shown to improve cardiac function in animal models of heart failure; cell therapy, with autologous bone marrow derived mononuclear cells, or autogenous mesenchymal cells, which can be administered as cryopreserved off the shelf products, seem to be promising in both preclinical and early clinical heart failure trials; and long-term ventricular assistance devices are now used increasingly as a destination therapy in patients with advanced heart failure. In selected patients, left ventricular assistance can lead to myocardial recovery and explantation of the device. The approaches to the treatment of heart failure described, when used alone or in combination, could become important weapons in the war against heart failure.

Effectiveness of gene delivery systems for pluripotent and differentiated cells

Human embryonic stem cells (hESC) and induced pluripotent stem cells (hiPSC) assert a great future for the cardiovascular diseases, both to study them and to explore therapies. However, a comprehensive assessment of the viral vectors used to modify these cells is lacking. In this study, we aimed to compare the transduction efficiency of recombinant adeno-associated vectors (AAV), adenoviruses and lentiviral vectors in hESC, hiPSC, and the derived cardiomyocytes. In undifferentiated cells, adenoviral and lentiviral vectors were superior, whereas in differentiated cells AAV surpassed at least lentiviral vectors. We also tested four AAV serotypes, 1, 2, 6, and 9, of which 2 and 6 were superior in their transduction efficiency. Interestingly, we observed that AAVs severely diminished the viability of undifferentiated cells, an effect mediated by induction of cell cycle arrest genes and apoptosis. Furthermore, we show that the transduction efficiency of the different viral vectors correlates with the abundance of their respective receptors. Finally, adenoviral delivery of the calcium-transporting ATPase SERCA2a to hESC and hiPSC-derived cardiomyocytes successfully resulted in faster calcium reuptake. In conclusion, adenoviral vectors prove to be efficient for both differentiated and undifferentiated lines, whereas lentiviral vectors are more applicable to undifferentiated cells and AAVs to differentiated cells.

Altered myocardial calcium cycling and energetics in heart failure--a rational approach for disease treatment

Cardiomyocyte function depends on coordinated movements of calcium into and out of the cell and the proper delivery of ATP to energy-utilizing enzymes. Defects in calcium-handling proteins and abnormal energy metabolism are features of heart failure. Recent discoveries have led to gene-based therapies targeting calcium-transporting or -binding proteins, such as the cardiac sarco(endo)plasmic reticulum calcium ATPase (SERCA2a), leading to improvements in calcium homeostasis and excitation-contraction coupling. Here we review impaired calcium cycling and energetics in heart failure, assessing their roles from both a mutually exclusive and interdependent viewpoint, and discuss therapies that may improve the failing myocardium.

Guidelines for translational research in heart failure

Heart failure (HF) remains a major cause of death and hospitalization worldwide. Despite medical advances, the prognosis of HF remains poor and new therapeutic approaches are urgently needed. The development of new therapies for HF is hindered by inappropriate or incomplete preclinical studies. In these guidelines, we present a number of recommendations to enhance similarity between HF animal models and the human condition in order to reduce the chances of failure in subsequent clinical trials. We propose different approaches to address safety as well as efficacy of new therapeutic products. We also propose that good practice rules are followed from the outset so that the chances of eventual approval by regulatory agencies increase. We hope that these guidelines will help improve the translation of results from animal models to humans and thereby contribute to more successful clinical trials and development of new therapies for HF.

Phospholamban interactome in cardiac contractility and survival: A new vision of an old friend

Depressed sarcoplasmic reticulum (SR) calcium cycling, reflecting impaired SR Ca-transport and Ca-release, is a key and universal characteristic of human and experimental heart failure. These SR processes are regulated by multimeric protein complexes, including protein kinases and phosphatases as well as their anchoring and regulatory subunits that fine-tune Ca-handling in specific SR sub-compartments. SR Ca-transport is mediated by the SR Ca-ATPase (SERCA2a) and its regulatory phosphoprotein, phospholamban (PLN). Dephosphorylated PLN is an inhibitor of SERCA2a and phosphorylation by protein kinase A (PKA) or calcium-calmodulin-dependent protein kinases (CAMKII) relieves these inhibitory effects. Recent studies identified additional regulatory proteins, associated with PLN, that control SR Ca-transport. These include the inhibitor-1 (I-1) of protein phosphatase 1 (PP1), the small heat shock protein 20 (Hsp20) and the HS-1 associated protein X-1 (HAX1). In addition, the intra-luminal histidine-rich calcium binding protein (HRC) has been shown to interact with both SERCA2a and triadin. Notably, there is physical and direct interaction between these protein players, mediating a fine-cross talk between SR Ca-uptake, storage and release. Importantly, regulation of SR Ca-cycling by the PLN/SERCA interactome does not only impact cardiomyocyte contractility, but also survival and remodeling. Indeed, naturally occurring variants in these Ca-cycling genes modulate their activity and interactions with other protein partners, resulting in depressed contractility and accelerated remodeling. These genetic variants may serve as potential prognostic or diagnostic markers in cardiac pathophysiology.

The Use of Gene Therapy for Ablation of Atrial Fibrillation

Atrial fibrillation is the most common clinically significant cardiac arrhythmia, increasing the risk of stroke, heart failure and morbidity and mortality. Current therapies, including rate control and rhythm control by antiarrhythmic drugs or ablation therapy, are moderately effective but far from optimal. Gene therapy has the potential to become an attractive alternative to currently available therapies for atrial fibrillation. Various gene transfer vectors have been developed for cardiovascular disease with viral vectors being most widely used due to their high efficiency. Several gene delivery methods have been employed on different therapeutic targets. With increasing understanding of arrhythmia mechanisms, novel therapeutic targets have been discovered. This review will evaluate state-of-art gene therapy strategies and approaches including sinus rhythm restoration and ventricular rate control that could eventually prevent or eliminate atrial fibrillation in patients.

Characterizing preclinical models of ischemic heart failure: differences between LAD and LCx infarctions

Large animal studies are an important step toward clinical translation of novel therapeutic approaches. We aimed to establish an ischemic heart failure (HF) model with a larger myocardial infarction (MI) relative to previous studies, and characterize the functional and structural features of this model. An MI was induced by occluding the proximal left anterior descending artery (LAD; n = 15) or the proximal left circumflex artery (LCx; n = 6) in Yorkshire pigs. Three pigs with sham procedures were also included. All pigs underwent hemodynamic and echocardiographic assessments before MI, at 1 mo, and 3 mo after MI. Analyses of left ventricular (LV) myocardial mechanics by means of strains and torsion were performed using speckle-tracking echocardiography and compared between the groups. The proximal LAD MI approach induced larger infarct sizes (14.2 ± 3.2% vs. 10.6 ± 1.9%, P = 0.03), depressed systolic function (LV ejection fraction; 39.8 ± 7.5% vs. 54.1 ± 4.6%, P < 0.001), and more LV remodeling (end-systolic volume index; 82 ± 25 ml/m(2) vs. 51 ± 18 ml/m(2), P = 0.02, LAD vs. LCx, respectively) compared with the LCx MI approach without compromising the survival rate. At the papillary muscle level, echocardiographic strain analysis revealed no differences in radial and circumferential strain between LAD and LCx MIs. However, in contrast with the LCx MI, the LAD MI resulted in significantly decreased longitudinal strain. The proximal LAD MI model induces more LV remodeling and depressed LV function relative to the LCx MI model. Location of MI significantly impacts the severity of HF, thus careful consideration is required when choosing an MI model for preclinical HF studies.

Cardiomyocyte-specific expression of CRNK, the C-terminal domain of PYK2, maintains ventricular function and slows ventricular remodeling in a mouse model of dilated cardiomyopathy

Up-regulation and activation of PYK2, a member of the FAK family of protein tyrosine kinases, is involved in the pathogenesis of left ventricular (LV) remodeling and heart failure (HF). PYK2 activation can be prevented by CRNK, the C-terminal domain of PYK2. We previously demonstrated that adenoviral-mediated CRNK gene transfer improved survival and LV function, and slowed LV remodeling in a rat model of coronary artery ligation-induced HF. We now interrogate whether cardiomyocyte-specific, transgenic CRNK expression prevents LV remodeling and HF in a mouse model of dilated cardiomyopathy (DCM) caused by constitutively active Protein Kinase Cε (caPKCε). Transgenic (TG; FVB/N background) mice were engineered to express rat CRNK under control of the α-myosin heavy chain promoter, and crossed with FVB/N mice with cardiomyocyte-specific expression of caPKCε to create double TG mice. LV structure, function, and gene expression were evaluated in all 4 groups (nonTG FVB/N; caPKCε(+/-); CRNK(+/-); and caPKCε×CRNK (PXC) double TG mice) at 1, 3, 6, 9 and 12mo of age. CRNK expression followed a Mendelian distribution, and CRNK mice developed and survived normally through 12mo. Cardiac structure, function and selected gene expression of CRNK mice were similar to nonTG littermates. CRNK had no effect on caPKCε expression and vice versa. PYK2 was up-regulated ~6-fold in caPKCε mice, who developed a non-hypertrophic, progressive DCM with reduced systolic (Contractility Index=151±5 vs. 90±4s(-1)) and diastolic (Tau=7.5±0.5 vs. 14.7±1.3ms) function, and LV dilatation (LV Remodeling Index (LVRI)=4.2±0.1 vs. 6.0±0.3 for FVB/N vs. caPKCε mice, respectively; P<0.05 for each at 12mo). In double TG PXC mice, CRNK expression significantly prolonged survival, improved contractile function (Contractile Index=115±8s(-1); Tau=9.5±1.0ms), and reduced LV remodeling (LVRI=4.9±0.1). Cardiomyocyte-specific expression of CRNK improves contractile function and slows LV remodeling in a mouse model of DCM.

Sizing up models of heart failure: Proteomics from flies to humans

Cardiovascular disease is the leading cause of death in the western world. Heart failure is a heterogeneous and complex syndrome, arising from various etiologies, which result in cellular phenotypes that vary from patient to patient. The ability to utilize genetic manipulation and biochemical experimentation in animal models has made them indispensable in the study of this chronic condition. Similarly, proteomics has been helpful for elucidating complicated cellular and molecular phenotypes and has the potential to identify circulating biomarkers and drug targets for therapeutic intervention. In this review, the use of human samples and animal model systems (pig, dog, rat, mouse, zebrafish, and fruit fly) in cardiac research is discussed. Additionally, the protein sequence homology between these species and the extent of conservation at the level of the phospho-proteome in major kinase signaling cascades involved in heart failure are investigated.

SUMO-1 gene transfer improves cardiac function in a large-animal model of heart failure

Recently, the impact of small ubiquitin-related modifier 1 (SUMO-1) on the regulation and preservation of sarcoplasmic reticulum calcium adenosine triphosphatase (SERCA2a) function was discovered. The amount of myocardial SUMO-1 is decreased in failing hearts, and its knockdown results in severe heart failure (HF) in mice. In a previous study, we showed that SUMO-1 gene transfer substantially improved cardiac function in a murine model of pressure overload-induced HF. Toward clinical translation, we evaluated in this study the effects of SUMO-1 gene transfer in a swine model of ischemic HF. One month after balloon occlusion of the proximal left anterior descending artery followed by reperfusion, the animals were randomized to receive either SUMO-1 at two doses, SERCA2a, or both by adeno-associated vector type 1 (AAV1) gene transfer via antegrade coronary infusion. Control animals received saline infusions. After gene delivery, there was a significant increase in the maximum rate of pressure rise [dP/dt(max)] that was most pronounced in the group that received both SUMO-1 and SERCA2a. The left ventricular ejection fraction (LVEF) improved after high-dose SUMO-1 with or without SERCA2a gene delivery, whereas there was a decline in LVEF in the animals receiving saline. Furthermore, the dilatation of LV volumes was prevented in the treatment groups. SUMO-1 gene transfer therefore improved cardiac function and stabilized LV volumes in a large-animal model of HF. These results support the critical role of SUMO-1 in SERCA2a function and underline the therapeutic potential of SUMO-1 for HF patients.

Anti-inflammatory loaded poly-lactic glycolic acid nanoparticle formulations to enhance myocardial gene transfer: an in-vitro assessment of a drug/gene combination therapeutic approach for direct injection

Background

Cardiac gene therapy for heart disease is a major translational research area with potential, yet problems with safe and efficient gene transfer into cardiac muscle remain unresolved. Existing methodology to increase vector uptake include modifying the viral vector, non-viral particle encapsulation and or delivery with device systems. These advanced methods have made improvements, however fail to address the key problem of inflammation in the myocardium, which is known to reduce vector uptake and contribute to immunogenic adverse events. Here we propose an alternative method to co-deliver anti-inflammatory drugs in a controlled release polymer with gene product to improve therapeutic effects.

Methods

A robust, double emulsion production process was developed to encapsulate drugs into nanoparticles. Briefly in this proof of concept study, aspirin and prednisolone anti-inflammatory drugs were encapsulated in various poly-lactic glycolic acid polymer (PLGA) formulations. The resultant particle systems were characterized, co-delivered with GFP plasmid, and evaluated in harvested myocytes in culture for uptake.

Results

High quality nanoparticles were harvested from multiple production runs, with an average 64 ± 10 mg yield. Four distinct particle drug system combinations were characterized and evaluated in vitro: PLGA(50:50) Aspirin, PLGA(65:35) Prednisolone, PLGA(65:35) Aspirin and PLGA(50:50) Prednisolone Particles consisted of spherical shape with a narrow size distribution 265 ± 104 nm as found in scanning electron microscopy imaging. Prednisolone particles regardless of PLGA type were found on average ≈ 100 nm smaller than the aspirin types. All four groups demonstrated high zeta potential stability and re-constitution testing prior to in vitro. In vitro results demonstrated co uptake of GFP plasmid (green) and drug loaded particles (red) in culture with no incidence of toxicity.

Conclusions

Nano formulated anti-inflammatories in combination with standalone gene product therapy may offer a clinical solution to maximize cardiac gene therapy product effects while minimizing the risk of the host response in the inflammatory myocardial environment.

Targeting sarcoplasmic reticulum calcium ATPase by gene therapy

Although pharmacologic therapies have provided gains in reducing the mortality of heart failure, the rising incidence of the disease requires new approaches to combat its health burden. Twenty-five years ago, abnormal calcium cycling was identified as a characteristic of failing human myocardium. Sarcoplasmic reticulum calcium ATPase (SERCA2a), the sarcoplasmic reticulum calcium pump, was found to be a key factor in the alteration of calcium cycling. With the advancement of gene vectors, SERCA2a emerged as an attractive clinical target for gene delivery purposes. Using adeno-associated virus constructs, SERCA2a upregulation has been found to improve myocardial function in animal models. The clinical benefits of overexpressing SERCA2a have been demonstrated in the phase I study Calcium Upregulation by Percutaneous Administration of Gene Therapy in Cardiac Disease (CUPID). This study has demonstrated that a persistent expression of the transgene SERCA2a is associated with a significant improvement in associated biochemical alterations and clinical symptoms of heart failure. In the coming years, additional targets will likely emerge that are amenable to genetic manipulations along with the development of more advanced vector systems with safer delivery approaches.

A novel artificial microRNA expressing AAV vector for phospholamban silencing in cardiomyocytes improves Ca2+ uptake into the sarcoplasmic reticulum

In failing rat hearts, post-transcriptonal inhibition of phospholamban (PLB) expression by AAV9 vector-mediated cardiac delivery of short hairpin RNAs directed against PLB (shPLBr) improves both impaired SERCA2a controlled Ca²⁺ cycling and contractile dysfunction. Cardiac delivery of shPLB, however, was reported to cause cardiac toxicity in canines. Thus we developed a new AAV vector, scAAV6-amiR155-PLBr, expressing a novel engineered artificial microRNA (amiR155-PLBr) directed against PLB under control of a heart-specific hybrid promoter. Its PLB silencing efficiency and safety were compared with those of an AAV vector expressing shPLBr (scAAV6-shPLBr) from an ubiquitously active U6 promoter. Investigations were carried out in cultured neonatal rat cardiomyocytes (CM) over a period of 14 days. Compared to shPLBr, amiR155-PLBr was expressed at a significantly lower level, resulting in delayed and less pronounced PLB silencing. Despite decreased knockdown efficiency of scAAV6-amiR155-PLBr, a similar increase of the SERCA2a-catalyzed Ca²⁺ uptake into sarcoplasmic reticulum (SR) vesicles was observed for both the shPLBr and amiR155-PLBr vectors. Proteomic analysis confirmed PLB silencing of both therapeutic vectors and revealed that shPLBr, but not the amiR155-PLBr vector, increased the proinflammatory proteins STAT3, STAT1 and activated STAT1 phosphorylation at the key amino acid residue Tyr701. Quantitative RT-PCR analysis detected alterations in the expression of several cardiac microRNAs after treatment of CM with scAAV6-shPLBr and scAAV6-amiR155-PLBr, as well as after treatment with its related amiR155- and shRNAs-expressing control AAV vectors. The results demonstrate that scAAV6-amiR155-PLBr is capable of enhancing the Ca²⁺ transport function of the cardiac SR PLB/SERCA2a system as efficiently as scAAV6-shPLBr while offering a superior safety profile.