Gene Therapy For Heart Failure Research Articles

Oligomeric Interactions in Cardiac Calcium Regulation

We used time-resolved fluorescence resonance energy transfer (TR-FRET) to determine the oligomeric state of phospholamban (PLB) and its inhibited target, sarcoplasmic reticulum Ca-ATPase (SERCA). Previous work on our lab has shown that PLB is primarily pentameric but SERCA binds preferentially to the monomeric form in lipid vesicles. Recent EM studies suggest that the PLB pentamer might also bind to SERCA. We tested this hypothesis by labeling SERCA at C674 with a fluorescent donor (TMRIA) and labeling PLB at K3 with a non-fluorescent acceptor (MGITC), then reconstituting the proteins into lipid vesicles and performing TR-FRET as a function of the fraction of acceptor-labeled PLB (xA), keeping the total PLB/SERCA molar ratio constant at 10. Simulations showed that if a PLB monomer binds to SERCA, the dependence of FRET on xA should be linear, but the binding of a PLB oligomer should produce distinct curvature in the plot. The observed plot was quite linear, and was indistinguishable from control experiments using a monomeric mutant of PLB. We conclude that PLB binds to SERCA only as a monomer. These results have important implications for the design of PLB mutants to be used in gene therapy for heart failure.

Sarcoplasmic reticulum Ca2+ ATPase as a therapeutic target for heart failure

The cardiac isoform of the sarco/endoplasmic reticulum Ca2+ATPase (SERCA2a) plays a major role in controlling excitation/contraction coupling. In both experimental and clinical heart failure, SERCA2a expression is significantly reduced which leads to abnormal Ca2+ handling and deficient contractility. A large number of studies in isolated cardiac myocytes and in small and large animal models of heart failure showed that restoring SERCA2a expression by gene transfer corrects the contractile abnormalities and improves energetics and electrical remodeling. Following a long line of investigation, a clinical trial is underway to restore SERCA2a expression in patients with heart failure using adeno-associated virus type 1. This review addresses the following issues regarding heart failure gene therapy: i) new insights on calcium regulation by SERCA2a; ii) SERCA2a as a gene therapy target in animal models of heart failure; iii) advances in the development of viral vectors and gene delivery; and iv) clinical trials on heart failure using SERCA2a. This review focuses on the new advances in SERCA2a- targeted gene therapy made in the last three years. In conclusion, SERCA2a is an important therapeutic target in various cardiovascular disorders. Ongoing clinical gene therapy trials will provide answers on its safety and applicability.

Dilated cardiomyopathy alters the expression patterns of CAR and other adenoviral receptors in human heart

Gene therapy trials for heart failure have demonstrated the key role of efficient gene transfer in achieving therapeutic efficacy. An attractive approach to improve adenoviral gene transfer is to use alternative virus serotypes with modified tropism. We performed a detailed analysis of cardiac expression of receptors for several adenovirus serotypes with a focus on differential expression of CAR and CD46, as adenoviruses targeting these receptors have been used in various applications. Explanted hearts from patients with DCM and healthy donors were analyzed using Q-RT-PCR, western blot and immunohistochemistry. Q-RT-PCR and Western analyses revealed robust expression of all receptors except CD80 in normal hearts with lower expression levels in DCM. Immunohistochemical analyses demonstrated that CD46 expression was somewhat higher than CAR both in normal and DCM hearts with highest levels of expression in intramyocardial coronary vessels. Total CAR expression was upregulated in DCM. Triple staining on these vessels demonstrated that both CAR and CD46 were confined to the subendothelial layer in normal hearts. The situation was clearly different in DCM, where both CAR and CD46 were expressed by endothelial cells. The induction of expression of CAR and CD46 by endothelial cells in DCM suggests that viruses targeting these receptors could more easily gain entry to heart cells after intravascular administration. This finding thus has potential implications for the development of targeted gene therapy for heart failure.

Gene and Cell Therapy for Heart Failure

Cardiac gene and cell therapy have both entered clinical trials aimed at ameliorating ventricular dysfunction in patients with chronic congestive heart failure. The transduction of myocardial cells with viral constructs encoding a specific cardiomyocyte Ca(2+) pump in the sarcoplasmic reticulum (SR), SRCa(2+)-ATPase has been shown to correct deficient Ca(2+) handling in cardiomyocytes and improvements in contractility in preclinical studies, thus leading to the first clinical trial of gene therapy for heart failure. In cell therapy, it is not clear whether beneficial effects are cell-type specific and how improvements in contractility are brought about. Despite these uncertainties, a number of clinical trials are under way, supported by safety and efficacy data from trials of cell therapy in the setting of myocardial infarction. Safety concerns for gene therapy center on inflammatory and immune responses triggered by viral constructs, and for cell therapy with myoblast cells, the major concern is increased incidence of ventricular arrhythmia after cell transplantation. Principles and mechanisms of action of gene and cell therapy for heart failure are discussed, together with the potential influence of reactive oxygen species on the efficacy of these treatments and the status of myocardial-delivery techniques for viral constructs and cells.

Heart Failure Gene Therapy: Closer to Reality

Professor Walter Koch is currently a Director at the Center for Translational Medicine and Vice Chairman for Research in the Department of Medicine at Jefferson Medical College, Thomas Jefferson University, PA, USA. Professor Koch started his career as a Research Associate at the Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA. His work is based around heart failure and the molecular mechanisms involved in the regulation of signaling through cardiovascular adrenergic receptors, the study of G-proteincoupled receptor function and signaling, and heart failure gene therapy. His current studies are investigating into the use of novel viral-mediated myocardial gene delivery for use in congestive heart failure, with an aim at developing reproducible surgical means of gene therapy. He is also involved in research to understand novel molecular signaling mechanisms responsible for reversible cardiac injury and potential repair.

Clinical Summaries

Clinical Summaries

Myocardial Adeno-Associated Virus Serotype 6–βARKct Gene Therapy Improves Cardiac Function and Normalizes the Neurohormonal Axis in Chronic Heart Failure

The upregulation of G protein-coupled receptor kinase 2 in failing myocardium appears to contribute to dysfunctional beta-adrenergic receptor (betaAR) signaling and cardiac function. The peptide betaARKct, which can inhibit the activation of G protein-coupled receptor kinase 2 and improve betaAR signaling, has been shown in transgenic models and short-term gene transfer experiments to rescue heart failure (HF). This study was designed to evaluate long-term betaARKct expression in HF with the use of stable myocardial gene delivery with adeno-associated virus serotype 6 (AAV6). In HF rats, we delivered betaARKct or green fluorescent protein as a control via AAV6-mediated direct intramyocardial injection. We also treated groups with concurrent administration of the beta-blocker metoprolol. We found robust and long-term transgene expression in the left ventricle at least 12 weeks after delivery. betaARKct significantly improved cardiac contractility and reversed left ventricular remodeling, which was accompanied by a normalization of the neurohormonal (catecholamines and aldosterone) status of the chronic HF animals, including normalization of cardiac betaAR signaling. Addition of metoprolol neither enhanced nor decreased betaARKct-mediated beneficial effects, although metoprolol alone, despite not improving contractility, prevented further deterioration of the left ventricle. Long-term cardiac AAV6-betaARKct gene therapy in HF results in sustained improvement of global cardiac function and reversal of remodeling at least in part as a result of a normalization of the neurohormonal signaling axis. In addition, betaARKct alone improves outcomes more than a beta-blocker alone, whereas both treatments are compatible. These findings show that betaARKct gene therapy can be of long-term therapeutic value in HF.

Abstract 2883: Retroinfusion-facilitated Inotropic AAV9-S100A1 Gene Therapy Restores Global Cardiac Function In A Clinically Relevant Pig Heart Failure Model

Background: Cardiac expression of the Ca-dependent inotropic protein S100A1 is decreased in human end-stage heart failure (HF) and cardiomyocyte-targeted viral-based S100A1 gene transfer rescued failing myocardium in small animal models in vivo and in vitro via improved systolic and diastolic sarcoplasmic reticulum Ca-handling. We therefore hypothesized that cardioselective AAV9-S100A1 gene therapy will improve cardiac performance in a large animal experimental HF model under clinical conditions. Methods and Results: Left ventricular (LV) posterolateral myocardial infarction (MI) was induced in pigs by occlusion of the left coronary circumflex artery and resulted in LV failure (HF) 2 weeks post-MI reflected by a 40% and 27% reduction in LV +dp/dt max. and EF, respectively, as assessed by LV catheterization and echocardiography. Post-MI HF pigs were then randomized for retroinfusion of AAV9-luciferase (luc; n=6, 1.5×10 13 total viral particles, tvp) and AAV9-S100A1 (S100A1; n=6, 1.5×10 13 tvp) driven by a cardioselective promoter via the anterior cardiac vein while the left anterior descending artery was temporarily occluded. 14 weeks after cardiac gene transfer, the S100A1-treated HF group showed significantly enhanced S100A1 protein expression (+46.7±17.9%, P<0.05 vs. control groups) in targeted remote LV myocardium and improved indices of cardiac function and remodeling (luc vs. S100A1: +dp/dtmax: 983±81 vs. 1526±83 mmHg/s, EF: 39±2.1 vs. 61±3.7 %, P<0.05 S100A1 vs. luc, LV endsystolic diameter: luc 4.45±0.1 vs. S100A1 3.43 ±0.1 cm, P<0.05 S100A1 vs. luc, HR: 72±4 vs. 69±2, beats/min, P=n.s. S100A1 vs. luc). Importantly, analyses of renal, hepatic and hematopoetic function showed no alteration as assessed by unchanged transaminases, retention values and white blood cell counts compared to sham pigs. Conclusions: Our translational study provides proof of concept that AAV9-S100A1 based HF gene therapy is feasible and restores cardiac function in a large animal HF model under clinical conditions. Next, certified toxicological analysis and different AAV9-S100A1 dosage protocols will be assessed to eventually advance to first phase I/II clinical studies determining therapeutic efficiency of cardiac S100A1 gene therapy in HF patients.

Gene Therapy in Heart Failure

With increasing knowledge of basic molecular mechanisms governing the development of heart failure (HF), the possibility of specifically targeting key pathological players is evolving. Technology allowing for efficient in vivo transduction of myocardial tissue with long-term expression of a transgene enables translation of basic mechanistic knowledge into potential gene therapy approaches. Gene therapy in HF is in its infancy clinically with the predominant amount of experience being from animal models. Nevertheless, this challenging and promising field is gaining momentum as recent preclinical studies in larger animals have been carried out and, importantly, there are 2 newly initiated phase I clinical trials for HF gene therapy. To put it simply, 2 parameters are needed for achieving success with HF gene therapy: (1) clearly identified detrimental/beneficial molecular targets; and (2) the means to manipulate these targets at a molecular level in a sufficient number of cardiac cells. However, several obstacles do exist on our way to efficient and safe gene transfer to human myocardium. Some of these obstacles are discussed in this review; however, it primarily focuses on the molecular target systems that have been subjected to intense investigation over the last decade in an attempt to make gene therapy for human HF a reality.

Rapid screen for heart failure autonomic nervous system imbalance in cardiomyopathic BIO TO‐2 hamsters

The cardiomyopathic BIO TO-2 hamster is a recognized model for heart failure including autonomic nervous system dysfunction. Recent studies using BIO TO-2 hamster that has a large deletion in the -sarcoglycan gene have provided promising results showing the efficacy of gene therapy in heart failure. Methods to accelerate preclinical testing of gene therapy and new drugs for heart disease are urgently needed. This study demonstrates a rapid non-invasive screen for characterizing autonomic nervous system imbalance in BIO TO-2 hamsters thus showing its usefulness in the preclinical testing of drugs for heart failure. EKGs were recorded non-invasively through the underside of the paws in conscious BIO TO-2 hamsters and controls (BIO F1-B) using an electrode-embedded platform. Each recording took only a few minutes. Heart rate was significantly higher in BIO TO-2 hamsters. Time domain heart rate variability, an index of parasympathetic tone, was significantly lower, as was the coefficient of variance of the RR interval. Power spectrum analysis showed a reduced high-frequency power spectrum and an increased low/high-frequency ratio, indicating autonomic imbalance with an increased sympathetic tone and a decreased parasympathetic tone in BIO TO-2 hamsters. Thus, autonomic nervous system dysfunction of the heart in hamsters can be quickly and noninvasively quantified. This technique and the findings are of practical significance in accelerating the testing of new therapeutic modalities in the treatment of heart failure.

Bone marrow stem cells-based SERCA2a gene therapy for heart failure after acute myocardium infarction

Explore the possibility of MSC to be used to target delivery of therapeutic gene and evaluate the therapeutic effects among gene therapy, MSC transplantation and MSC-based gene therapy. MSC were infected with an adenoviral expression vector carrying SERCA2a. SD female rats were used to make animal model with heart failure after AMI and divided into 4 groups randomly. Group I (n = 7) received SERCA2a gene therapy, group II (n = 7) received MSC transplantation, group III (n = 8) received MSC infected with SERCA2a gene transplantation, and group IV (n = 7) received empty adenoviral vector. Cardiac function was evaluated by echocardiography and physiological recorder. SERCA2a gene and protein expression were evaluated by RT-PCR and Western blot respectively. Compared to group IV, EF and FS of group I, group II and group III were elevated significantly on 14 days after therapy (EF: 67.7 +/- 3.9, 62.6 +/- 4.0, 67.9 +/- 3.7 versus 45.0 +/- 2.2; FS: 33.9 +/- 1.9, 31.1 +/- 2.0, 33.9 +/- 1.9 versus 22.5 +/- 1.1, P < 0.05). While the elevation values of EF and FS began to reduce in group I 14 days after, it continued to increase in both group II and group III. Absolute value of LVEDP at 21 days after treatment was increased in group I, group II and group III compared to group IV (5.3 mm Hg +/- 1.2 mm Hg, 6.0 +/- 1.3 mm Hg, 6.2 mm Hg +/- 1.2 mm Hg versus 1.5 mm Hg +/- 0.2 mm Hg, P < 0.05), as well as absolute value of DP/dtmin (4756 mm Hg/s +/- 270 mm Hg/s, 5028 mm Hg/s +/- 253 mm Hg/s, 5283 mm Hg/s +/- 363 mm Hg/s versus 3201 mm Hg/s +/- 211 mm Hg/s, P < 0.05). DP/dtmax at 21 days after treatment increased in group I, group II and group III compared to group IV (6026 mm Hg/s +/- 281 mm Hg/s, 6278 mm Hg/s +/- 319 mm Hg/s, 7057 mm Hg/s +/- 389 mm Hg/s versus 5293 mm Hg/s +/- 360 mm Hg/s, P < 0.05). SERCA2a expressions and enzyme activity were significantly stronger in group I and group III than in group II and group IV. It showed that all MSC transplantation, SERCA2a gene therapy and MSC-based gene therapy could enhance cardiac function. The recovered heart function continued to improve in MSC transplantation group and MSC-based gene therapy group up to 21 days, however slowed down in single gene therapy group in 21 days. Such therapeutic tendency of MSC-based gene therapy was stronger than that of MSC transplantation. Thus, MSC proved an effective platform for the targeted delivery of therapeutic gene.

Industry Watch

Biota Discovers New Potent Antivirals. Celladon Partners with V-Kardia on Development of Percutaneous Delivery of Gene Therapy for Heart Failure. Regenera Closes Multimillion Dollar Drug Deal. Napo Pharma Collaborates with AsiaPharm. Matrix Buys Over Belgian Company Docpharma. Ranbaxy Buys Portfolio from Spain's EFARMES. Japan's MediBIC and ReaMetrix India Team up. Medical &amp; Biological Labs and DNAVEC Establish Joint Venture Company in China. Britsol-Meyers Squibb Collaborates with Korea's Celltrion. YM Biosciences Partners with Kuhnil to Develop Nimotuzumab. A Company that Helps Translate Basic Research into Useful Biomedical Products. InfleXion Corp Develops Diagnostic Kits. GNI and Shanghai Genomics Merge. MerLion Announces Collaboration Agreement with Sankyo. Schering AG Sets Up Asia-Pacific Headquarters in Singapore. Three Global Companies Invest US$112 Million to Form Joint Venture: Interpharma, Quintiles and Temasek Holdings

Explorations into development of myocardial gene therapy for heart failure

Explorations into development of myocardial gene therapy for heart failure

Administration of insulin?like growth factor?1 (IGF?1) improves both structure and function of delta?sarcoglycan deficient cardiac muscle in the hamster

Dilated cardiomyopathies (DCM) are due to progressive dilatation of the cardiac cavities and thinning of the ventricular walls and lead unavoidably to heart failure. They represent a major cause for heart transplantation and, therefore, defining an efficient symptomatic treatment for DCM remains a challenge. We have taken advantage of the hamster strain CHF147 that displays progressive cardiomyopathy leading to heart failure to test whether stimulation of a hypertrophic pathway could delay the process of dilatation.Six month old CHF147 hamsters were treated with IGF-1 so that we could compare the efficacy of systemic administration of human recombinant IGF-1 protein (rh IGF-1) at low dose to that of direct myocardial injections of a plasmid DNA containing IGF-1 cDNA (pCMV-IGF1).IGF-1 treatment did not induce a significant variation of ventricle mass, but preserved left ventricular (LV) wall thickness and delayed dilatation of cardiac cavities when compared to non-treated hamsters. Together with this reduction of dilatation, we also noted a reduction in the amount of interstitial collagen. Furthermore, IGF-1 treatment induced beneficial effects on cardiac function since treated hamsters presented improved cardiac output and stroke volume, decreased end diastolic pressure when compared to nontreated hamsters and also showed a trend towards increased contractility (dP/dt(max)).This study provides evidence that IGF-1 treatment induces beneficial structural and functional effects on DCM of CHF147 hamsters, hence making this molecule a promising candidate for future gene therapy of heart failure due to DCM.

Gene Therapy in Congestive Heart Failure

Although research and development of gene therapy have encountered several difficulties in recent years, they have also begun to show potential for the treatment of acquired and inherited human diseases. Gene therapy may have wide applicability for the treatment of numerous cardiovascular diseases, including congestive heart failure (CHF), ischemic heart disease, and cardiomyopathy. CHF remains a leading cause of death and morbidity in industrialized nations, and the number of patients with CHF continues to increase as the population ages. Pharmacological therapies control symptoms, reduce left ventricular (LV) dilation, improve function, and reduce mortality. These therapies control the disease but do not cure it. Currently, however, the growing knowledge of molecular mechanisms involved in myocardial dysfunction has allowed the identification of potential therapeutic targets designed with the aim of curing CHF. Several studies in animal models have provided hope that gene therapy may be one of the future strategies for the treatment of clinical CHF. In these studies, myocardial gene transfer has been used to target at least 3 different biological pathways that play a crucial role in the pathophysiology of CHF: Intracellular calcium signaling, β1-adrenergic receptor (β1-AR) signaling, and antiapoptotic signaling. The activity of sarcoplasmic reticulum Ca2+ ATPase (SERCA2a) is decreased in failing myocardium, and this results in abnormal Ca2+ handling.1 In an animal model of heart failure, Miyamoto et al2 showed that in vivo overexpression of SERCA2a, achieved by catheter injection of an adenovirus carrying the SERCA2a gene into the aortic root, restored systolic and diastolic function to normal levels. In another study, Muller et al3 analyzed the chronic overexpression of SERCA2a in both normal and pressure-overloaded hearts (induced by abdominal aortic banding of transgenic rats). Overexpression of SERCA2a resulted in a …

Functional characterization of the human atrial essential myosin light chain (hALC-1) in a transgenic rat model.

Most patients with hypertrophic cardiomyopathy and congenital heart diseases express the atrial essential myosin light chains (ALC-1) in their ventricles, partially replacing the ventricular essential light chains (VLC-1). This VLC-1/ALC-1 isoform shift is correlated with an increase in cross-bridge cycling kinetics as measured using skinned fibers from the hypertrophied ventricles of human hearts. To study the functional importance of hALC-1 in the intact perfused heart, we generated a transgenic rat model (TGR) overexpressing hALC-1 in the heart. Twelve-week-old TGR rats expressed 17 +/- 4 microg hALC-1 per mg of whole SDS-soluble protein. Their perfused heart contractility parameters were evaluated using the Langendorff preparation. Expression of hALC-1 was accompanied by statistically significant improvements (P<0.001) in the contractile parameters of the hearts of the TGR compared to the age matched control (WKY) animals, represented by increases from 20.8 +/- 2.3 to 45.1 +/- 3.6 mmHg/g heart weight in the developed left ventricular pressure, 1,035.7 +/- 89.8 to 2,181 +/- 135.4 mmHg/s in the contraction rate, and 713 +/- 60.2 to 1,364 +/- 137.4 mmHg/s in the relaxation rate in the WKY and the TGR groups respectively. Characterizing the functional effects of hALC-1 at the whole organ level represents a step towards gene therapy of heart failure.

Myocardial gene therapy.

Gene therapy is proving likely to be a viable alternative to conventional therapies in coronary artery disease and heart failure. Phase 1 clinical trials indicate high levels of safety and clinical benefits with gene therapy using angiogenic growth factors in myocardial ischaemia. Although gene therapy for heart failure is still at the pre-clinical stage, experimental data indicate that therapeutic angiogenesis using short-term gene expression may elicit functional improvement in affected individuals.

Gene therapy in heart failure

Despite various therapeutic approaches heart failure remains one of the leading causes of death. Over the last decade we have acquired a greater knowledge of the pathophysiology of heart failure on a molecular level. In addition, tools for cardiac gene delivery have been developed. Therefore, the possibility of gene therapy for heart failure merits consideration at this time. We will first examine several targets that have been considered for therapeutic intervention and then review recent advances in cardiac gene delivery in animal models. Gene transfer represents not only a potential therapeutic modality but also provides an important tool to help validate specific targets. Several approaches, especially those targeting sarcoplasmic reticulum calcium transport, show promise in animal models of heart failure and in myopathic cardiomyocytes derived from patients.It remains a challenge to close the gap between these basic investigations and the clinical use of gene therapy in heart failure. Experiments in rodents will need to be extended to large-animal models to assess the efficacy and safety of vectors and delivery systems. Based on a growing understanding of heart failure pathogenesis and improvement in delivery systems, there is reason for cautious optimism for the future.

SERCA Pump Level is a Critical Determinant of Ca2+Homeostasis and Cardiac Contractility

The control of intracellular calcium is central to regulation of cardiac contractility. A defect in SR Ca2+transport and SR Ca2+ATPase pump activity and expression level has been implicated as a major player in cardiac dysfunction. However, a precise cause–effect relationship between alterations in SERCA pump level and cardiac contractility could not be established from these studies. Progress in transgenic mouse technology and adenoviral gene transfer has provided new tools to investigate the role of SERCA pump level in the heart. This review focuses on how alterations in SERCA level affect Ca2+homeostasis and cardiac contractility. It discusses the consequences of altered SERCA pump levels for the expression and activity of other Ca2+handling proteins. Furthermore, the use of SERCA pump as a therapeutic target for gene therapy of heart failure is evaluated.

Proteins of the sarcoplasmic reticulum as potential targets for gene therapy of heart failure

Proteins of the sarcoplasmic reticulum as potential targets for gene therapy of heart failure