Rescue of hereditary form of dilated cardiomyopathy by rAAV-mediated somatic gene therapy: amelioration of morphological findings, sarcolemmal permeability, cardiac performances, and the prognosis of TO-2 hamsters

Whole exome sequence reveals genetic profiles of primary cardiomyopathy and genotype-phenotype association in Chinese population

BACKGROUND

Primary cardiomyopathies are major causes of heart failure, placing a substantial burden on both individuals and society. Revealing its genetic profiles can lead to a better understanding of the mechanism and is critical for disease prevention and treatment.

METHOD

Primary cardiomyopathy patients were enrolled and whole exome sequence was conducted to analyze their genetic profiles. Retrospective clinical information extraction and analysis of sequence data were implemented.

RESULTS

A total of 77 primary cardiomyopathy patients were enrolled, comprising 65 patients with dilated cardiomyopathy (DCM) and 12 with hypertrophic cardiomyopathy (HCM). Among the DCM patients, 13 variants classified as pathogenic (P) or likely pathogenic (LP) were identified in 12 patients (18.46%), predominantly in genes associated with the nuclear envelope and sarcomere. Among HCM patients, 6 P/LP variants were discovered in 6 (50%) patients. Taking variants of uncertain significance (VUS) into consideration, an analysis of the association between the number of variants carried by patients and their clinical characteristics revealed that DCM patients with more than one variant had a higher proportion of hyperuricemia.

CONCLUSIONS

We map a comprehensive profile of primary cardiomyopathy in Chinese population and, for the first time, identify a possible association between hyperuricemia and the number of genetic variants carried by DCM patients.

Proteomic Profiling of Plasma- and Gut-Derived Extracellular Vesicles in Obesity

Obesity entails metabolic alterations across multiple organs, highlighting the role of inter-organ communication in its pathogenesis. Extracellular vesicles (EVs) are communication agents in physiological and pathological conditions, and although they have been associated with obesity comorbidities, their protein cargo in this context remains largely unknown. To decipher the messages encapsulated in EVs, we isolated plasma-derived EVs from a diet-induced obese murine model. Obese plasma EVs exhibited a decline in protein diversity while control EVs revealed significant enrichment in protein-folding functions, highlighting the importance of proper folding in maintaining metabolic homeostasis. Previously, we revealed that gut-derived EVs' proteome holds particular significance in obesity. Here, we compared plasma and gut EVs and identified four proteins exclusively present in the control state of both EVs, revealing the potential for a non-invasive assessment of gut health by analyzing blood-derived EVs. Given the relevance of post-translational modifications (PTMs), we observed a shift in chromatin-related proteins from glycation to acetylation in obese gut EVs, suggesting a regulatory mechanism targeting DNA transcription during obesity. This study provides valuable insights into novel roles of EVs and protein PTMs in the intricate mechanisms underlying obesity, shedding light on potential biomarkers and pathways for future research.

Pigs with δ-sarcoglycan deficiency exhibit traits of genetic cardiomyopathy

Genetic cardiomyopathy is a group of intractable cardiovascular disorders involving heterogeneous genetic contribution. This heterogeneity has hindered the development of life-saving therapies for this serious disease. Genetic mutations in dystrophin and its associated glycoproteins cause cardiomuscular dysfunction. Large animal models incorporating these genetic defects are crucial for developing effective medical treatments, such as tissue regeneration and gene therapy. In the present study, we knocked out the δ-sarcoglycan (δ-SG) gene (SGCD) in domestic pig by using a combination of efficient de novo gene editing and somatic cell nuclear transfer. Loss of δ-SG expression in the SGCD knockout pigs caused a concomitant reduction in the levels of α-, β-, and γ-SG in the cardiac and skeletal sarcolemma, resulting in systolic dysfunction, myocardial tissue degeneration, and sudden death. These animals exhibited symptoms resembling human genetic cardiomyopathy and are thus promising for use in preclinical studies of next-generation therapies.

CaMKII/calpain interaction mediates ischemia/reperfusion injury in isolated rat hearts

Previous studies indicated that Ca²⁺/calmodulin-dependent kinase II (CaMKII), a kinase involved in the modulation of ryanodine receptor activity, activates Ca²⁺-regulated protease μ-calpain to promote myocardial ischemia/reperfusion injury. This study was performed to explore the underlying mechanisms in CaMKII-induced calpain activation to better understand heart injury. To examine the Ca²⁺ paradox and ischemia/reperfusion injury, isolated rat hearts were subjected to a Ca²⁺-free solution for 3 min, or left coronary artery occlusion for 40 min, prior to restoration of normal perfusion. Blockade of trans-sarcoplasmic reticulum Ca²⁺ flux using ryanodine and thapsigargin failed to prevent Ca²⁺ paradox-induced heart injury. In contrast, the Ca²⁺ paradox increased CaMKII auto-phosphorylation at Thr²⁸⁷, while the CaMKII inhibitor KN-62 and the Na⁺/Ca²⁺ exchanger inhibitor KB-R7943 alleviated heart injury and calpain activity. Intriguingly, the binding of μ-calpain large subunit calpain-1 (CAPN1) to phospho-CaMKII was blunted by both inhibitors. Thus, a Ca²⁺ leak via the ryanodine receptor is not an essential element in CaMKII-elicited calpain activation. In hearts receiving vector injection, ischemia/reperfusion caused elevated calpain activity and α-fodrin degradation, along with membrane integrity damage, similar to the effects noted in control hearts. Importantly, all these alterations were diminished with delivery of adeno-associated virus expressing mutant CaMKIIδC T287A. Ischemia/reperfusion increased CaMKII auto-phosphorylation and binding of CAPN1 to phospho-CaMKII, and facilitated the translocation of phospho-CaMKII and CAPN1 to the plasma membrane, all of which were reversed by injecting CaMKII mutant. Furthermore, the relocation capacity and the interaction of CaMKII with CAPN1 appeared to be dependent upon CaMKII autophosphorylation, as its mutant delivery increased the level of CaMKII, but did not increase membrane content of CaMKII and CAPN1, or their interactions. Together, CaMKII/calpain interaction represents a new avenue for mediating myocardial ischemia/reperfusion injury, and CaMKII likely serves as both a kinase and a carrier, thereby promoting calpain membrane translocation and activation.

Translating emerging molecular genetic insights into clinical practice in inherited cardiomyopathies

Cardiomyopathies are primarily genetic disorders of the myocardium associated with higher risk of life-threatening cardiac arrhythmias, heart failure, and sudden cardiac death. The evolving knowledge in genomic medicine during the last decade has reshaped our understanding of cardiomyopathies as diseases of multifactorial nature and complex pathophysiology. Genetic testing in cardiomyopathies has subsequently grown from primarily a research tool into an essential clinical evaluation piece with important clinical implications for patients and their families. The purpose of this review is to provide with a contemporary insight into the implications of genetic testing in diagnosis, therapy, and prognosis of patients with inherited cardiomyopathies. Here, we summarize the contemporary knowledge on genotype-phenotype correlations in inherited cardiomyopathies and highlight the recent significant achievements in the field of translational cardiovascular genetics.

CaMKII inhibition mitigates ischemia/reperfusion-elicited calpain activation and the damage to membrane skeleton proteins in isolated rat hearts

Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) has been implicated in myocardial ischemia/reperfusion (IR) injury. The aim of this study was to determine the effect of CaMKII on the damage to membrane skeleton proteins, which is an important cause of IR injury. Isolated rat hearts were subjected to 45-min global ischemia/2-h reperfusion. Both KN-62 and KN-93 were used to inhibit CaMKII. Compared with controls, the hearts in the IR group exhibited remarkable myocardial injury area, LDH release, cell apoptosis and contractile dysfunction, along with an increase in the phosphorylation of CaMKII and its substrate phospholamban. Treatment with either KN-62 or KN-93 mitigated both the heart injury and the phosphorylation of CaMKII and phospholamban. The analysis of cell skeleton proteins revealed that IR injury resulted in an increase in the 150-kDa fragments resulting from the degradation of α-fodrin and dystrophin translocating from the sarcolemmal membrane to the cytosol and a decrease in the 220-kDa isoform of ankyrin-B. As expected, Evans blue dye staining showed an increase in membrane permeability or membrane rupture in the IR group. All of these alterations were alleviated by treatment with either KN-62 or KN-93. In addition, both KN-62 and KN-93 blocked the activity and membrane recruitment of calpain, a key protease responsible for destroying cell skeleton proteins during IR injury. In conclusion, our data provide evidence that damage to membrane skeleton proteins via calpain is a destructive downstream event of CaMKII activation in the setting of myocardial IR injury.

Prospect of gene therapy for cardiomyopathy in hereditary muscular dystrophy

INTRODUCTION

Cardiac involvement is a common feature in muscular dystrophies. It presents as heart failure and/or arrhythmia. Traditionally, dystrophic cardiomyopathy is treated with symptom-relieving medications. Identification of disease-causing genes and investigation on pathogenic mechanisms have opened new opportunities to treat dystrophic cardiomyopathy with gene therapy. Replacing/repairing the mutated gene and/or targeting the pathogenic process/mechanisms using alternative genes may attenuate heart disease in muscular dystrophies.

AREAS COVERED

Duchenne muscular dystrophy is the most common muscular dystrophy. Duchenne cardiomyopathy has been the primary focus of ongoing dystrophic cardiomyopathy gene therapy studies. Here, we use Duchenne cardiomyopathy gene therapy to showcase recent developments and to outline the path forward. We also discuss gene therapy status for cardiomyopathy associated with limb-girdle and congenital muscular dystrophies, and myotonic dystrophy.

EXPERT OPINION

Gene therapy for dystrophic cardiomyopathy has taken a slow but steady path forward. Preclinical studies over the last decades have addressed many fundamental questions. Adeno-associated virus-mediated gene therapy has significantly improved the outcomes in rodent models of Duchenne and limb girdle muscular dystrophies. Validation of these encouraging results in large animal models will pave the way to future human trials.

The CC genotype of the delta-sarcoglycan gene polymorphism rs13170573 is associated with obstructive sleep apnea in the Chinese population

Obstructive sleep apnea (OSA) is a highly heterogeneous sleep disorder, and increasing evidence suggests that genetic factors play a role in the etiology of OSA. Airway muscle dysfunction might promote pharyngeal collapsibility, mutations or single nucleotide polymorphisms (SNPs) in the delta-sarcoglycan (SCGD) gene associated with muscle dysfunction. To evaluate if SCGD gene SNPs are associated with OSA, 101 individuals without OSA and 97 OSA patients were recruited randomly. The genotype distributions of SNPs (rs157350, rs7715464, rs32076, rs13170573 and rs1835919) in case and control populations were evaluated. The GG, GC and CC genotypes of rs13170573 in control and OSA groups were 51.5% and 37.1%, 36.6% and 35.1%, and 11.9% and 27.8%, respectively. Significantly fewer OSA patients possessed the GG genotype and significantly more possessed the CC genotype compared with controls. Further multivariate logistic regression analysis showed that the CC genotype was an independent risk factor for OSA, with an odds ratio (OR) of 2.17 (95% confidence interval [CI]: 1.19-6.01). Other factors, such as age ≥ 50 years, male gender, body mass index (BMI) ≥ 25 kg/m(2), low-density lipoprotein cholesterol (LDL-C) level ≥ 3.33 mg/dL, smoking and hypertension, were also independent risk factors for OSA in our multivariate logistic regression model.

SERCA2a gene therapy can improve symptomatic heart failure in δ-sarcoglycan-deficient animals

The loss of dystrophin or its associated proteins results in the development of muscle wasting frequently associated with cardiomyopathy. Contractile cardiac tissue is injured and replaced by fibrous tissue or fatty infiltrates, leading to a progressive decrease of the contractile force and finally to end-stage heart failure. At the time symptoms appear, restoration of a functional allele of the causative gene might not be sufficient to prevent disease progression. Alterations in Ca(2+) transport and intracellular calcium levels have been implicated in many types of pathological processes, especially in heart disease. On the basis of a gene transfer strategy, we analyzed the therapeutic efficacy of primary gene correction in a δ-sarcoglycan (δ-SG)-deficient animal model versus gene transfer of the Ca(2+) pump hSERCA2a (human sarco-endoplasmic reticulum calcium ATPase 2a), at a symptomatic stage of heart disease. Our results strongly suggest that restoration of δ-SG at this stage of disease will not lead to improved clinical outcome. However, restoration of proper Ca(2+) handling by means of amplifying SERCA2a expression in the myocardium can lead to functional improvement. Abnormalities in Ca(2+) handling play an important role in disease progression toward heart failure, and increased SERCA2a levels appear to significantly improve cardiac contraction and relaxation. Beneficial effects persist at least over a period of 6 months, and the evolution of cardiac functional parameters paralleled those of normal controls. Furthermore, we demonstrate that a plasmid formulation based on amphiphilic block copolymers can provide a safe and efficient platform for myocardial gene therapies. The use of synthetic formulations for myocardial gene transfer might thus overcome one of the major hurdles linked to viral vectors, that is, repeat administrations.

An emerging adeno-associated viral vector pipeline for cardiac gene therapy

The naturally occurring adeno-associated virus (AAV) isolates display diverse tissue tropisms in different hosts. Robust cardiac transduction in particular has been reported for certain AAV strains. Successful applications of these AAV strains in preclinical and clinical settings with a focus on treating cardiovascular disease continue to be reported. At the same time, these studies have highlighted challenges such as cross-species variability in AAV tropism, transduction efficiency, and immunity. Continued progress in our understanding of AAV capsid structure and biology has provided the rationale for designing improved vectors that can possibly address these concerns. The current report provides an overview of cardiotropic AAV, existing gaps in our knowledge, and newly engineered AAV strains that are viable candidates for the cardiac gene therapy clinic.

Therapeutic potential of genes in cardiac repair

Cardiovascular diseases remain the primary reason of premature death and contribute to a major percentage of global patient morbidity. Recent knowledge in the molecular mechanisms of myocardial complications have identified novel therapeutic targets along with the availability of vectors that offer the chance for designing gene therapy technique for protection and revival of the diseased heart functions. Gene transfer procedure into the myocardium is demonstrated through direct injection of plasmid DNA or through the coronary vasculature using the direct or indirect delivery of viral vectors. Direct DNA injection to the myocardium is reported to be of immense value in research studies that aims at understanding the activities of various elements in myocardium. It is also deemed vital for investigating the effect of the myocardial pathophysiology on expression of the foreign genes that are transferred. Gene therapies have been reported to heal cardiac pathologies such as myocardial ischemia, heart failure and inherited myopathies in several animal models. The results obtained from these animal studies have also encouraged a flurry of early clinical trials. This translational research has been triggered by an enhanced understanding of the biological mechanisms involved in tissue repair after ischemic injury. While safety concerns take utmost priority in these trials, several combinational therapies, various routes and dose of delivery are being tested before concrete optimization and complete potential of gene therapy is convincingly understood.

Enhancement of recombinant adeno-associated virus mediated transgene expression by targeted echo-contrast agent

Ultrasound-targeted microbubble destruction (UTMD) has been recently developed for destroying bubbles carrying drugs or genes, thereby permitting local release of these target molecules. We investigated whether SonoVue®, a new contrast agent that contains phospholipid-stabilized microbubbles filled with sulfur hexafluoride vapor, is effective at delivering a recombinant adeno-associated viral (rAAV) vector to the rat heart by UTMD. Serotype-2 (rAAV2) marked with green fluorescent protein (GFP) as a reporter gene was attached to the surface of sulfur hexafluoride-filled microbubbles. Microbubbles were infused into the tail vein of rats with or without simultaneous echocardiography. Additional controls included ultrasound microbubbles that did not contain virus, virus alone, and virus plus ultrasound. One group underwent echocardiographic destruction of microbubbles followed by rAAV2-GFP infusion. Rats were killed after 4 weeks and examined for GFP expression. Green fluorescence was detected in all groups that received the rAAV2-GFP vector, indicating expression of the rAAV2 transgene; however, GFP expression in the UTMD group was significantly higher than that in control groups. We conclude that ultrasound-mediated destruction mediated by SonoVue is a promising method for delivery of rAAV2 to the heart in vivo.

Progress in gene therapy of dystrophic heart disease

The heart is frequently afflicted in muscular dystrophy. In severe cases, cardiac lesion may directly result in death. Over the years, pharmacological and/or surgical interventions have been the mainstay to alleviate cardiac symptoms in muscular dystrophy patients. Although these traditional modalities remain useful, the emerging field of gene therapy has now provided an unprecedented opportunity to transform our thinking/approach in the treatment of dystrophic heart disease. In fact, the premise is already in place for genetic correction. Gene mutations have been identified and animal models are available for several types of muscular dystrophy. Most importantly, innovative strategies have been developed to effectively deliver therapeutic genes to the heart. Dystrophin-deficient Duchenne cardiomyopathy is associated with Duchenne muscular dystrophy (DMD), the most common lethal muscular dystrophy. Considering its high incidence, there has been a considerable interest and significant input in the development of Duchenne cardiomyopathy gene therapy. Using Duchenne cardiomyopathy as an example, here we illustrate the struggles and successes experienced in the burgeoning field of dystrophic heart disease gene therapy. In light of abundant and highly promising data with the adeno-associated virus (AAV) vector, we have specially emphasized on AAV-mediated gene therapy. Besides DMD, we have also discussed gene therapy for treating cardiac diseases in other muscular dystrophies such as limb-girdle muscular dystrophy.

Gene therapy in skeletal muscle mediated by adeno-associated virus vectors

Adeno-associated virus (AAV) is the most promising gene delivery vehicle for muscle-directed gene therapy. AAV's natural tropism to muscle cells, long-term persistent transgene expression, multiple serotypes, as well as its minimal immune response have made AAV vectors well suited for muscle-directed gene therapy. AAV vector-mediated gene delivery to augment muscle structural proteins, such as dystrophin and sarcoglycans, offers great hope for muscular dystrophy patients. In addition, muscle can be used as a therapeutic platform for AAV vectors to express nonmuscle secretory/regulatory pathway proteins for diabetes, atherosclerosis, hemophilia, cancer, etc. AAV vector can be delivered into both skeletal muscle and cardiac muscle by means of local, regional, and systemic administrations. Successful animal studies have led to several noteworthy clinical trials involving muscle-directed gene therapy. In this chapter, we describe the basic methodology that is currently utilized in the area of AAV-mediated muscle-directed gene therapy. These methods include vector delivery route, vector dosage, detection of transgene expression by immunostaining and western blot, determination of vector copy numbers and quantification of mRNA expression, as well as potential immune responses involved in AAV delivery. Technical details and tips leading to successful experimentation are also discussed.

Gene therapy targets in heart failure: the path to translation

Heart failure (HF) is the common end point of cardiac diseases. Despite the optimization of therapeutic strategies and the consequent overall reduction in HF-related mortality, the key underlying intracellular signal transduction abnormalities have not been addressed directly. In this regard, the gaps in modern HF therapy include derangement of β-adrenergic receptor (β-AR) signaling, Ca(2+) disbalances, cardiac myocyte death, diastolic dysfunction, and monogenetic cardiomyopathies. In this review we discuss the potential of gene therapy to fill these gaps and rectify abnormalities in intracellular signaling. We also examine current vector technology and currently available vector-delivery strategies, and we delineate promising gene therapy structures. Finally, we analyze potential limitations related to the transfer of successful preclinical gene therapy approaches to HF treatment in the clinic, as well as impending strategies aimed at overcoming these limitations.

AAV vectors for cardiac gene transfer: experimental tools and clinical opportunities

Since the first demonstration of in vivo gene transfer into myocardium there have been a series of advancements that have driven the evolution of cardiac gene delivery from an experimental tool into a therapy currently at the threshold of becoming a viable clinical option. Innovative methods have been established to address practical challenges related to tissue-type specificity, choice of delivery vehicle, potency of the delivered material, and delivery route. Most importantly for therapeutic purposes, these strategies are being thoroughly tested to ensure safety of the delivery system and the delivered genetic material. This review focuses on the development of recombinant adeno-associated virus (rAAV) as one of the most valuable cardiac gene transfer agents available today. Various forms of rAAV have been used to deliver "pre-event" cardiac protection and to temper the severity of hypertrophy, cardiac ischemia, or infarct size. Adeno-associated virus (AAV) vectors have also been functional delivery tools for cardiac gene expression knockdown studies and successfully improving the cardiac aspects of several metabolic and neuromuscular diseases. Viral capsid manipulations along with the development of tissue-specific and regulated promoters have greatly increased the utility of rAAV-mediated gene transfer. Important clinical studies are currently underway to evaluate AAV-based cardiac gene delivery in humans.

A single direct injection into the left ventricular wall of an adeno-associated virus 9 (AAV9) vector expressing extracellular superoxide dismutase from the cardiac troponin-T promoter protects mice against myocardial infarction

BACKGROUND

Localized administration of a highly efficient gene delivery system in combination with a cardiac-selective promoter may provide a favorable biosafety profile in clinical applications such as coronary artery bypass graft surgery, where regions of myocardium can be readily injected to protect them against the potential threat of future ischemic events.

METHODS

Adeno-associated virus (AAV) vectors expressing luciferase or enhanced green fluorescent protein (eGFP) packaged into AAV serotypes 1, 2, 6, 8 and 9 were injected into the left ventricular (LV) wall of adult mice to determine the time course, magnitude and distribution of gene expression. An AAV9 vector expressing extracellular superoxide dismutase (EcSOD) from the cardiac troponin T (cTnT) promoter was then directly injected into the LV wall of adult mice. Myocardial infarction was induced 4 weeks after injection and infarct size was determined by triphenyltetrazolium chloride and phthalo blue staining.

RESULTS

Serotypes AAV 9, 8, 1 and 6 provided early onset of gene expression in the heart with minimal extra-cardiac gene expression. AAV9 provided the highest magnitude of gene expression. Immunostaining for eGFP showed expression spanning the anterior to posterior walls from the mid ventricle to the apex. A single direct injection of the AAV9 vector bearing EcSOD ( n  = 5) decreased the mean infarct size by 50% compared to the eGFP control group (n = 8) (44 ± 7% versus 22 ± 5%; p = 0.04).

CONCLUSIONS

AAV serotype 9 is highly efficient for cardiac gene delivery, as evidenced by early onset and high-level gene expression. AAV9-mediated, cardiac selective overexpression of EcSOD from the cTnT promoter significantly reduced infarct size in mice.

δ-Sarcoglycan-deficient muscular dystrophy: from discovery to therapeutic approaches

Mutations in the δ-sarcoglycan gene cause limb-girdle muscular dystrophy 2F (LGMD2F), an autosomal recessive disease that causes progressive weakness and wasting of the proximal limb muscles and often has cardiac involvement. Here we review the clinical implications of LGMD2F and discuss the current understanding of the putative mechanisms underlying its pathogenesis. Preclinical research has benefited enormously from various animal models of δ-sarcoglycan deficiency, which have helped researchers to explore therapeutic approaches for both muscular dystrophy and cardiomyopathy.

Delta-sarcoglycan gene therapy halts progression of cardiac dysfunction, improves respiratory failure, and prolongs life in myopathic hamsters

BACKGROUND

The BIO14.6 hamster provides a useful model of hereditary cardiomyopathies and muscular dystrophy. Previous δ-sarcoglycan (δSG) gene therapy (GT) studies were limited to neonatal and young adult animals and prevented the development of cardiac and skeletal muscle dysfunction. GT of a pseudophosphorylated mutant of phospholamban (S16EPLN) moderately alleviated the progression of cardiomyopathy.

METHODS AND RESULTS

We treated 4-month-old BIO14.6 hamsters with established cardiac and skeletal muscle diseases intravenously with a serotype-9 adeno-associated viral vector carrying δSG alone or in combination with S16EPLN. Before treatment at age 14 weeks, the left ventricular fractional shortening by echocardiography was 31.3% versus 45.8% in normal hamsters. In a randomized trial, GT halted progression of left ventricular dilation and left ventricular dysfunction. Also, respiratory function improved. Addition of S16EPLN had no significant additional effects. δSG-GT prevented severe degeneration of the transverse tubular system in cardiomyocytes (electron tomography) and restored distribution of dystrophin and caveolin-3. All placebo-treated hamsters, except animals removed for the hemodynamic study, died with heart failure between 34 and 67 weeks of age. In the GT group, signs of cardiac and respiratory failure did not develop, and animals lived for 92 weeks or longer, an age comparable to that reported in normal hamsters.

CONCLUSION

GT was highly effective in BIO14.6 hamsters even when given in late-stage disease, a finding that may carry implications for the future treatment of hereditary cardiac and muscle diseases in humans.

Functional proteomic analysis of experimental autoimmune myocarditis-induced chronic heart failure in the rat

Experimental autoimmune myocarditis (EAM)-induced heart failure in rats is used to study the pathogenesis of heart failure. Based on a proteomic analysis of soluble (S) and membranous (M) fractions extracted from ventricles of rats with a stable chronic form of EAM-induced heart failure, we assessed changes in protein levels and their correlation to heart functions to gain insights into the pathogenesis and to explore new targets for the treatment of heart failure. Proteins were separated by two-dimensional gel electrophoresis and silver stained spots were analyzed. In the S-fraction, 274+/-3 spots were detected in the normal (N)-group and 273+/-6 in the heart failure (HF)-group. In the HF-group, 26 of the spots were increased and 15 were decreased in intensity. In the M-fraction, 277+/-3 spots were detected in the N-group and 277+/-2 in the HF-group, with 20 spots increased and 10 decreased in intensity. We analyzed relationships between the expression of these proteins and 11 parameters of heart function, and found all the significantly changed spots to correlate with at least one of the parameters. We analyzed 49 spots that correlated with over 9 parameters of heart function using mass spectrometry, and identified 15 as proteins with increased expression including glucose regulated protein (GRP)78, an endoplasmic-stress related protein, and heat shock protein (HSP)90beta, a molecular chaperone, and 4 spots as proteins with decreased expression. It is suggested that in the heart failure model, GRP78 and HSP90beta play a role in the protection or deterioration of the heart and may be new targets for treatment.

Cardiac-targeted delivery of regulatory RNA molecules and genes for the treatment of heart failure

Ribonucleic acid (RNA) in its many facets of structure and function is becoming more fully understood, and, therefore, it is possible to design and use RNAs as valuable tools in molecular biology and medicine. Understanding of the role of RNAs within the cell has changed dramatically during the past few years. Therapeutic strategies based on non-coding regulatory RNAs include RNA interference (RNAi) for the silencing of specific genes, and microRNA (miRNA) modulations to alter complex gene expression patterns. Recent progress has allowed the targeting of therapeutic RNAi to the heart for the treatment of heart failure, and we discuss current strategies in this field. Owing to the peculiar biochemical properties of small RNA molecules, the actual therapeutic translation of findings in vitro or in cell cultures is more demanding than with small molecule drugs or proteins. The critical requirement for animal studies after pre-testing of RNAi tools in vitro likewise applies for miRNA modulations, which also have complex consequences for the recipient that are dependent on stability and distribution of the RNA tools. Problems in the field that are not yet fully solved are the prediction of targets and specificity of the RNA tools as well as their tissue-specific and regulatable expression. We discuss analogies and differences between regulatory RNA therapy and classical gene therapy, since recent breakthroughs in vector technology are of importance for both. Recent years have witnessed parallel progress in the fields of gene-based and regulatory RNA-based therapies that are likely to significantly expand the cardiovascular therapeutic repertoire within the next decade.

Hemodynamic alterations in the coronary circulation of cardiomyopathic hamsters: age and Ang II-dependent mechanisms

BACKGROUND

Coronary vasospasms have been reported in the early stages of cardiomyopathy in the Syrian cardiomyopathic hamster (CM; BIO-TO2 strain). It has been proposed these alterations could lead to ischemic heart disease and heart failure. However, the cause of these coronary abnormalities has not been established. In this study, we evaluated coronary hemodynamic to assess the role of Ang-II, reactive oxygen species, and nitric oxide (NO) in the development of these alterations in CM of 1, 2, and 6 months of age.

METHODS AND RESULTS

Excised hearts from control (CT) and CM were retroperfused with Krebs-Ringer bicarbonate solution (KRB), and coronary resistance (CR) was determined. The experimental protocol involved sequential infusions of the thromboxane analog U46619 (THX, 0.1micromol/L), bradykinin (BKN, 10micromol/L), and sodium nitroprusside (SNP, 10micromol/L). Similar experiments were conducted after treatment of hearts with N(omega)-nitro-L-arginine methyl ester (L-NAME, 10micromol/L). Basal CR increased with age, but no significant differences were observed between CT and CM. Reactivity to THX was increased (69%, P < .05) in 2-month-old CM when compared with CT. This effect was observed concomitantly with a significant reduction (53%, P < .05) in BKN-induced relaxation. The reduction in BKN-dependent relaxation was prevented by treatment for 1 month with the antioxidant N-acetylcysteine (1 g.kg.day), or losartan, an Ang II type 1 receptor blocker (10 mg.kg.day). Losartan also prevented the THX-induced increased reactivity in 2-month-old CM. The BKN-induced relaxation occurred through an L-NAME-sensitive pathway that was impaired with age. SNP dilation was preserved in all animal groups.

CONCLUSIONS

Our results strongly implicate vascular renin-angiotensin-system (RAS) and oxidative stress in endothelial dysfunction and increased reactivity in the early stages of cardiomyopathy in CM. These findings could be relevant to understand the etiology of cardiovascular disorders, in particular, in patients with sarcoglycanopathies.

Specific knockdown of delta-sarcoglycan gene in C2C12 in vitro causes post-translational loss of other sarcoglycans without mechanical stress

The precise role of delta-sarcoglycan (SG) that is constitutively expressed in skeletal muscle cells and may serve for maintaining the sarcolemmal integrity has not been identified. The delta-SG protein is at first among SG complex. To specifically identify the role in C(2)C(12) cells during the myogenesis, we screened several RNA interference (RNAi) candidates at first, and knocked down both levels of the mRNA and protein, employing adenovirus-mediated RNAi. We found no morphological alteration at both myoblast and myotube stages by suppression of delta-SG. The specific knockdown of delta-SG accompanied a concomitant decrease of alpha-, beta-, and gamma-SGs preserving normal levels of each transcript. As for the localization, alpha-, beta-, and gamma-SGs were weakly stained on the cell membrane in delta-SG knockdown cells, whereas each SG in control cell was localized both on the cell membrane and myoplasm abundantly. This enhanced post-translational loss would represent similitude of the progression of cardiomuscular diseases in vitro. Different from cardiac muscle cells, skeletal muscle cell culture without muscle contraction may imply that mechanical stress per se is not primarily involved in the progression of limb-girdle muscular dystrophy. Furthermore, we have observed translocation of calpain-2 to cell membrane in delta-SG knockdown cells, suggesting that Ca(2+)-sensitive proteases, calpains closely take part in post-translational proteolysis.

Designing heart performance by gene transfer

The birth of molecular cardiology can be traced to the development and implementation of high-fidelity genetic approaches for manipulating the heart. Recombinant viral vector-based technology offers a highly effective approach to genetically engineer cardiac muscle in vitro and in vivo. This review highlights discoveries made in cardiac muscle physiology through the use of targeted viral-mediated genetic modification. Here the history of cardiac gene transfer technology and the strengths and limitations of viral and nonviral vectors for gene delivery are reviewed. A comprehensive account is given of the application of gene transfer technology for studying key cardiac muscle targets including Ca(2+) handling, the sarcomere, the cytoskeleton, and signaling molecules and their posttranslational modifications. The primary objective of this review is to provide a thorough analysis of gene transfer studies for understanding cardiac physiology in health and disease. By comparing results obtained from gene transfer with those obtained from transgenesis and biophysical and biochemical methodologies, this review provides a global view of cardiac structure-function with an eye towards future areas of research. The data presented here serve as a basis for discovery of new therapeutic targets for remediation of acquired and inherited cardiac diseases.

Therapeutic possibilities in the autosomal recessive limb-girdle muscular dystrophies

Fourteen years ago, the first disease-causing mutation in a form of autosomal recessive limb-girdle muscular dystrophy was reported. Since then the number of genes has been extended to at least 14 and the phenotypic spectrum has been broadened. The generation of mouse models helped to improve our understanding of the pathogenesis of the disease and also served to study therapeutic possibilities. All autosomal recessive limb-girdle muscular dystrophies are rare diseases, which is one reason why there have been so very few controlled clinical trials. Other reasons are insufficient natural history data and the lack of standardized assessment criteria and validated outcome measures. Currently, therapeutic possibilities are mainly restricted to symptomatic treatment and the treatment of disease complications. On the other hand, new efforts in translational research and the development of molecular therapeutic approaches suggest that more promising clinical trials will be carried out in autosomal recessive limb-girdle muscular dystrophy in the next several years.

Recirculating cardiac delivery of AAV2/1SERCA2a improves myocardial function in an experimental model of heart failure in large animals

Abnormal excitation-contraction coupling is a key pathophysiologic component of heart failure (HF), and at a molecular level reduced expression of the sarcoplasmic reticulum (SR) Ca(2+) ATPase (SERCA2a) is a major contributor. Previous studies in small animals have suggested that restoration of SERCA function is beneficial in HF. Despite this promise, the means by which this information might be translated into potential clinical application remains uncertain. Using a recently established cardiac-directed recirculating method of gene delivery, we administered adeno-associated virus 2 (AAV2)/1SERCA2a to sheep with pacing-induced HF. We explored the effects of differing doses of AAV2/1SERCA2a (low 1 x 10(10) d.r.p.; medium 1 x 10(12) d.r.p. and high 1 x 10(13) d.r.p.) in conjunction with an intra-coronary delivery group (2.5 x 10(13) d.r.p.). At the end of the study, haemodynamic, echocardiographic, histopathologic and molecular biologic assessments were performed. Cardiac recirculation delivery of AAV2/1SERCA2a elicited a dose-dependent improvement in cardiac performance determined by left ventricular pressure analysis, (+d P/d t(max); low dose -220+/-70, P>0.05; medium dose 125+/-53, P<0.05; high dose 287+/-104, P<0.05) and echocardiographically (fractional shortening: low dose -3+/-2, P>0.05; medium dose 1+/-2, P>0.05; high dose 6.5+/-3.9, P<0.05). In addition to favourable haemodynamic effects, brain natriuretic peptide expression was reduced consistent with reversal of the HF molecular phenotype. In contrast, direct intra-coronary infusion did not elicit any effect on ventricular function. As such, AAV2/1SERCA2a elicits favourable functional and molecular actions when delivered in a mechanically targeted manner in an experimental model of HF. These observations lay a platform for potential clinical translation.

Augmentation of AAV-mediated cardiac gene transfer after systemic administration in adult rats

Adeno-associated virus (AAV)-6 or -9-pseudotyped vectors are suitable for efficient cardiac gene transfer after intravenous injection in mice. However, a systemic application in larger animals or humans would require very high doses of viral particles. Therefore, the aim of our study was to test if ultrasound-targeted microbubble destruction could augment cardiac transduction of AAV vectors after intravenous administration in rats. To analyze efficiency and specificity of gene transfer, microbubbles loaded with AAV-6 or -9 harboring a luciferase or enhanced green fluorescent protein (EGFP) reporter gene were infused into the jugular vein of adult Sprague-Dawley rats. During the infusion, high mechanical index ultrasound was administered to the heart. Control rats received the same amount of virus without microbubbles, but with ultrasound. After 4 weeks, organs were harvested and analyzed for reporter gene expression. In contrast to low cardiac expression after systemic transfer of the vector solution without microbubbles, ultrasound-targeted destruction of microbubbles significantly increased cardiac reporter activities between 6- and 20-fold. Analysis of spatial distribution of transgene expression using an AAV-9 vector encoding for EGFP revealed transmural expression predominantly in the left ventricular anterior wall. In conclusion, ultrasound targeted microbubble destruction augments cardiac transduction of AAV vectors in rats. This approach may be suitable for efficient, specific and noninvasive AAV-mediated gene transfer in larger animals or humans.

Gene-therapy delivery strategies in cardiology

Clinical gene-therapy approaches in cardiology have not fulfilled their promise in randomized, controlled trials, so far, despite striking effects in preclinical models. Lack of clinical success appears not to be related to an unexpected low potency of the therapeutic factors itself in humans, but has rather been attributed to limitations of the vector systems used to transfer the DNA, as well as application modes of the vector itself. Therefore, novel delivery strategies are required with increased efficiency and increased specificity. Recent improvements of vectors using targeting approaches in addition to the development of novel application strategies for cardiac or vascular gene transfer will improve gene delivery in future clinical approaches.

Specific knockdown of m-calpain blocks myogenesis with cDNA deduced from the corresponding RNAi

Fusion of mononuclear myoblast to multinucleated myotubes is crucial for myogenesis. Both mu- and m-calpain are ubiquitously expressed in most cells and are particularly abundant in muscle cells. Knockout of calpain-1 (catalytic subunit of mu-calpain) induced moderate platelet dysaggregation, preserving the normal development and growth, although knockout of calpain-2 (m-calpain) is lethal in mice. Therefore, there should be muscle-specific function of m-calpain per se. Previous methods lack direct evidence for the involvement of m-calpain, because the specific inhibitor to m-calpain has not been developed yet and the inhibition was less potent. Here, we show that screened RNA interference (RNAi) specifically blocked the m-calpain expression by 95% at both the protein and the activity levels. After transfection of adenovirus vector-mediated cDNA corresponding to the RNAi-induced short hairpin RNA, m-calpain in C(2)C(12) myoblasts was knocked down with no compensatory overexpression of mu-calpain or calpain-3. The specific knockdown strongly inhibited the fusion to multinucleated myotubes. In addition, the knockdown modestly blocked ubiquitous effects, including cell migration, cell spreading, and alignment of central stress fiberlike structures. These results may indicate that m-calpain requiring millimolar Ca(2+) level for the full activation plays specific roles in myogenesis, independent of mu-calpain, and leave us challenging problems in the future.

RNA Interference and MicroRNA Modulation for the Treatment of Cardiac Disorders

The current status and challenges of RNA interference (RNAi) and microRNA modulation strategies for the treatment of myocardial disorders are discussed and related to the classical gene therapeutic approaches of the past decade. Section 2 summarizes the key issues of current vector technologies which determine if they may be suitable for clinical translation of experimental RNAi or microRNA therapeutic protocols. We then present and discuss examples dealing with the potential of cardiac RNAi therapy. First, an approach to block a key early step in the pathogenesis of a virus-induced cardiomyopathy by RNAi targeting of a cellular receptor for cardiopathogenic viruses (Section 3). Second, an approach to improve cardiac function by RNAi targeting of late pathway of heart failure pathogenesis common to myocardial disorders of multiple etiologies. This strategy is directed at myocardial Ca²⁺ homeostasis which is disturbed in heart failure due to coronary heart disease, heart valve dysfunction, cardiac inflammation, or genetic defects (Section 4). Whereas the first type of strategies (directed at early pathogenesis) need to be tailor-made for each different type of pathomechanism, the second type (targeting late common pathways) has a much broader range of application. This advantage of the second type of approaches is of key importance since enormous efforts need to be undertaken before any regulatory RNA therapy enters the stage of possible clinical translation. If then the number of patients eligible for this protocol is large, the actual transformation of the experimental therapy into a new therapeutic option of clinical importance is far more likely to occur.

Which skeletal myoblasts and how to be transplanted for cardiac repair?

Clinical efficacy of skeletal myoblast (skMb) transplantation is controversial whether this treatment produces beneficial outcome in patients with dilated cardiomyopathy (DCM). Based on immunological tolerance between wild-type and DCM hamsters with the deletion of delta-sarcoglycan (SG) gene, skMb engraftment in TO-2 myocardium (3x10(5) cells in approximately 100mg heart) was verified by the donor-specific expression of delta-SG transgene constitutively produced throughout myogenesis. At 5 weeks after the transplantation, the cell rates expressing fast-myosin heavy chain (MHC) exceeded slow-MHC in delta-SG(+) cells. Fifteen weeks after (corresponding to approximately 12 years in humans), fast MHC(+) cells nullified, but the delta-SG(+) and slow MHC(+) cell number remained unaltered. These skMbs fused with host cardiomyocytes via connexin-43 and intercalated disc, modestly improving the hemodynamics without arrhythmia, when engrafted skMbs were sparsely disseminated in autopsied myocardium. These results provide us evidence that disseminating delivery of slow-MHC(+) myoblasts is promising for repairing DCM heart using histocompatible skeletal myoblasts in future.

Mutation of delta-sarcoglycan is associated with Ca(2+) -dependent vascular remodeling in the Syrian hamster

We examined whether mutation of the delta-sarcoglycan gene, which causes dilated cardiomyopathy, also alters the vascular smooth muscle cell (VSMC) phenotype and arterial function in the Syrian hamster CHF 147. Thoracic aorta media thickness showed marked variability in diseased hamsters with zones of atrophy and hypertrophied segments. CHF-147 VSMCs displayed a proliferating/"synthetic" phenotype characterized by the absence of the smooth muscle myosin heavy chain SM2, dystrophin, and Ca(2+)-handling proteins, and the presence of cyclin D1. In freshly isolated VSMCs from CHF 147 hamsters, voltage-independent basal Ca(2+) channels showed enhanced activity similar to that in proliferating wild-type (WT) cells. The transcription factor NFAT (nuclear factor of activated T cells) was spontaneously active in freshly isolated CHF 147 VSMCs, as in proliferating VSMCs from WT hamsters. Mibefradil inhibited B-type channels, NFAT activity, and VSMC proliferation. CHF 147 hamsters had abundant apoptotic cells distributed in patches along the aorta, and clusters of inactive mitochondria were observed in 25% of isolated CHF 147 cells, whereas no such clusters were seen in WT cells. In conclusion, mutation of the delta-sarcoglycan gene increases plasma membrane permeability to Ca(2+), activates the Ca(2+)-regulated transcription factor NFAT, and leads to spontaneous mitochondrial aggregation, causing abnormal VSMC proliferation and apoptosis.

Combined strategy using myoblasts and hepatocyte growth factor in dilated cardiomyopathic hamsters

BACKGROUND

There are few reports on treating dilated cardiomyopathy (DCM) with myoblast transplantation, and these show limited efficacy. Hepatocyte growth factor has cardioprotective effects on failed myocardium. Here, we combined these two treatments and analyzed cardiac function in DCM hamsters.

METHODS

Twenty-seven-week-old BIO TO-2 hamsters, which show moderate cardiac remodeling, were divided into four treatment groups: myoblast transplantation (T group, n = 24), human hepatocyte growth factor gene transfection (H group, n = 29), combined treatment (T+H group, n = 21), and medium alone (C group, n = 26).

RESULTS

Significantly better fractional shortening was observed in the T+H group compared with the others (14.9% +/- 1.0%, 11.7% +/- 1.5%, 11.3% +/- 1.3%, and 8.6% +/- 1.1 %, in the T+H, H, T, and C groups, respectively). Immunohistochemical analysis showed alpha- and beta-sarcoglycan expression in the hearts of the H and T+H groups but not in the other groups. There was less myocardial fibrosis in the H and T+H groups than in the other two, and neovascularization in the T+H group was significantly greater than in the other groups (266 +/- 24, 209 +/- 27, 199 +/- 36, and 96 +/- 17 vessels/mm2, in the T+H, H, T, and C groups, respectively). Survival was significantly prolonged in the H and T+H groups compared with the other groups.

CONCLUSIONS

Hepatocyte growth factor gene transfection and myoblast transplantation preserved the cardiac function of DCM hamsters, probably through different mechanisms, and the combined treatments preserved cardiac performance better than either treatment alone. The combined therapy is a promising strategy for treating DCM.

Granulocyte colony-stimulating factor improves left ventricular function of doxorubicin-induced cardiomyopathy

It is not well-known yet how granulocyte colony-stimulating factor (G-CSF) affects nonischemic cardiomyopathy, though its beneficial effects on acute myocardial infarction are well-established. We hypothesize that G-CSF beneficially might affect nonischemic cardiomyopathy through the direct cardioprotective effects. Here, we show that a single injection of doxorubicin (DOX, 15 mg/kg) induced left ventricular dilatation and dysfunction in mice within 2 weeks, and that these effects were significantly attenuated by human recombinant G-CSF (100 microg/kg/day for 5 days). G-CSF also protected hearts against DOX-induced cardiomyocyte atrophy/degeneration, fibrosis, inflammatory cell infiltration and down regulation of GATA-4 and sarcomeric proteins, myosin heavy chain, troponin I and desmin, both in vivo and in vitro. Cardiac cyclooxygenase-2 was upregulated and G-CSF receptor was downregulated in DOX-induced cardiomyopathy, but both of those effects were largely reversed by G-CSF. No DOX-induced apoptotic effects were seen, nor were there any changes in tumor necrosis factor-alpha or transforming growth factor-beta1 levels. Among downstream mediators of G-CSF receptor signaling, DOX-induced cardiomyopathy involved inactivation of extracellular signal-regulated protein kinase (ERK); the ERK inactivation was reversed by G-CSF. Inhibition of ERK activation, but not cyclooxygenase-2 inhibition, completely abolished beneficial effect of G-CSF on cardiac function. G-CSF did not promote differentiation of bone marrow cells into cardiomyocytes according to the experiment using green fluorescent protein-chimeric mice, and inhibition of CXCR4+ cell homing using AMD3100 did not diminish the effect of G-CSF. Finally, G-CSF was also effective when administered after cardiomyopathy was established. In conclusion, these findings imply the therapeutic usefulness of G-CSF mainly through restoring ERK activation against DOX-induced nonischemic cardiomyopathy.

Molecular and cellular basis of congenital heart disease

The cellular and molecular basis of congenital heart disease (CHD) is an evolving area of rapid discovery. This article introduced the basic mechanisms underlying cardiac development and CHD in order to permit a clear understanding of current diagnostics and therapeutics and their future development. It is clear that although significant advances have been made in understanding mechanisms controlling heart formation, the direct causes of CHD remain poorly defined. Future studies tha delineate the complexity of these mechanisms are required to provide a comprehensive understanding of the etiologies of CHD. Such understanding will lead to the development of novel approaches to prevention and therapy.

Intrapulmonary and intramyocardial gene transfer in rhesus monkeys (Macaca mulatta): safety and efficiency of HIV-1-derived lentiviral vectors for fetal gene delivery

Fetal gene transfer was studied using intrapulmonary and intramyocardial transfer of SIN HIV-1-derived lentiviral vectors expressing EGFP in rhesus monkeys. Fetuses were monitored sonographically during gestation and tissue analyses performed at term or 3 months postnatal age. Animals remained healthy during the study period as evidenced by normal growth, development, hematology, clinical chemistry, echocardiography, and pulmonary function tests. Strong pulmonary fluorescence was observed postnatally after fetal intrapulmonary delivery of lenti-CMV, but not lenti-SP-C, and compared to nontransferred controls. High EGFP copy numbers were found by quantitative PCR with both vector constructs in lung lobes (<or=15%) and EGFP copies were also detected in the diaphragm, pericardium, and thorax. No differences were found in lung:body weight ratios, percentage lung parenchyma, or overall morphology when compared to controls. For intramyocardial gene delivery, strong transgene expression was found within the myocardium and pericardium, and high EGFP copy numbers were found by quantitative PCR (3-36%). EGFP was also detected in the aorta, thorax, and diaphragm. These studies indicate that postnatal heart and lung development and function were not altered after fetal intraorgan gene transfer and subsequent transgene expression prenatally and postnatally, and gene transfer was restricted to the thoracic cavity with intrapulmonary and intramyocardial lentiviral vector-mediated gene delivery.

Autophagic cardiomyocyte death in cardiomyopathic hamsters and its prevention by granulocyte colony-stimulating factor

In UM-X7.1 hamster model of human dilated cardiomyopathy, heart failure progressively develops and causes 50% mortality by 30 weeks of age. Through ultrastructural analysis, we found that many cardiomyocytes of this model contain typical autophagic vacuoles including degraded mitochondria, glycogen granules, and myelin-like figures. In addition, ubiquitin, cathepsin D, and Rab7 were overexpressed as determined by immunoassays. Importantly, most cardiomyocytes with leaky plasma membranes were positive for cathepsin D, suggesting a direct link between autophagic degeneration and cell death. Meanwhile, cardiomyocyte apoptosis appeared insignificant. Granulocyte colony-stimulating factor (10 microg/kg/day), injected 5 days/week from 15 to 30 weeks of age, improved survival among 30-week-old hamsters (100% versus 53% in the untreated hamsters, P < 0.0001); ventricular function and remodeling, increased cardiomyocyte size, and reduced myocardial fibrosis followed by a dramatic reduction in the autophagic findings were also seen. Granulocyte colony-stimulating factor also down-regulated tumor necrosis factor-alpha and increased activities of Akt signal transducer and activator of transcription-3, and matrix metalloproteinases. However, there was no clear evidence of transdifferentiation from bone marrow cells into cardiomyocytes. In conclusion, autophagic death is important for cardiomyocyte loss in the cardiomyopathic hamster, and the beneficial effect of granulocyte colony-stimulating factor acts mainly via an anti-autophagic mechanism rather than anti-apo-ptosis or regeneration.

Pathways of myocyte death: implications for development of clinical laboratory biomarkers

The recognition that cardiac myocytes die by multiple mechanisms and thus substantially affect ventricular remodeling in diseased human hearts supports the concept of ongoing myocyte death in the progression of heart failure and constitutes the basis of this review. In addition, based on the pathophysiology of myocardial cell deaths, the present study emphasizes that currently methodologies, although with some inherent limitations, are available to recognize and measure quantitatively the contribution of myocyte cell death to the progression of the pathologic state of the heart. Our own studies show that application of such methodologies including modern microscopy techniques and the use of different molecular and immunohistochemical markers may generate the consensus that myocyte cell death is a quantifiable parameter in the normal and pathological human heart. The present study also demonstrates that myocyte cell death, apoptotic, oncotic or autophagic in nature, has to be regarded as an additional critical variable of the multifactorial events implicated in the alterations of cardiac anatomy and myocardial structure of the diseased human heart.

Treatment with granulocyte colony-stimulating factor ameliorates chronic heart failure

Chronic heart failure remains a leading cause of mortality. Although granulocyte colony-stimulating factor (G-CSF) is reported to have a beneficial affect on postinfarction cardiac remodeling and dysfunction when administered before the onset of or at the acute stage of myocardial infarction (MI), its effect on established heart failure is unknown. We show here that subcutaneous administration of G-CSF greatly improves the function of murine hearts failing due to a large, healed MI. G-CSF changed the geometry of the infarct scar from elongated and thin to short and thick, induced hypertrophy among surviving cardiomyocytes, and reduced myocardial fibrosis. Expression of G-CSF receptor was confirmed in failing hearts and was upregulated by G-CSF treatment. G-CSF treatment also led to activation of signal transducer and activator of transcription-3 and induction of GATA-4 and various sarcomeric proteins such as myosin heavy chain, troponin I and desmin. Expression of metalloproteinase-2 and -9 was also increased in G-CSF-treated hearts, while that of tumor necrosis factor-alpha, angiotensin II type 1 receptor (AT1) and transforming growth factor-beta1 was reduced. Although activation of Akt was noted in G-CSF-treated hearts, vessel density was unchanged, and apoptosis was too rare to exert a meaningful effect. No bone marrow-derived cardiomyocytes or vascular cells were detected in the failing hearts of green fluorescent protein chimeric mice. Finally, beneficial effects of G-CSF on cardiac function were found persisting long after discontinuing the treatment (2 weeks). Collectively, these findings suggest G-CSF administration could be an effective approach to treating chronic heart failure following a large MI.

Reorganization of cytoskeletal proteins and prolonged life expectancy caused by hepatocyte growth factor in a hamster model of late-phase dilated cardiomyopathy

OBJECTIVE

It has been postulated recently that changes in cytoskeletal and sarcolemmal proteins initiate a final common pathway for contractile dysfunction in dilated cardiomyopathy. In ischemic cardiomyopathy, hepatocyte growth factor plays an important role in reorganizing the impaired cytoskeletal proteins in several cell types. We have tested the hypothesis that hepatocyte growth factor might improve life expectancy through modification of the molecular process that contributes to impairment in dilated cardiomyopathy.

METHODS

Adult male 27-week-old BIO TO-2 hamsters, which show moderate cardiac remodeling, were divided into treatment groups that received (1) hemagglutinating virus of Japan liposomes containing human hepatocyte growth factor cDNA (H group), (2) culture medium (C group), or (3) sham operation (S group).

RESULTS

After the operation, echocardiography demonstrated that the enlarged left ventricular end-systolic dimension and decreased fractional shortening were significantly attenuated in the H group compared with the C group. There was significantly less myocardial fibrosis in the H group compared with the C group. Immunohistochemical analysis showed alpha-dystroglycan and alpha- and beta-sarcoglycan expression in the basement membrane beneath the cardiomyocytes in the H group, whereas no expression of these proteins was seen in the C group. The 40-week survival was significantly better in the H group than in the C and S groups.

CONCLUSION

An improved survival associated with transient reorganization of the cytoskeletal proteins and reduction in myocardial fibrosis was achieved by hepatocyte growth factor treatment in an adult hamster model of dilated cardiomyopathy. The results suggest a therapeutic potential of hepatocyte growth factor in the treatment of dilated cardiomyopathy.

Genetic therapies for cardiovascular diseases

Recent advances in understanding the molecular and cellular basis of cardiovascular diseases, together with the availability of tools for genetic manipulation of the cardiovascular system, offer possibilities for new treatments. Gene therapies have demonstrated potential usefulness for treating complex cardiovascular diseases, such as hypertension, atherosclerosis and myocardial ischemia, in various animal models. Some of these experimental therapies are now undergoing clinical evaluation in patients with cardiovascular disease. However, the successful transition of these therapies into mainstream clinical practice awaits further improvements to vector platforms and delivery tools and the documentation of clinical feasibility, safety and efficacy through multi-center randomized trials.

A novel paradigm for therapeutic basis of advanced heart failure--assessment by gene therapy

The precise mechanism(s) of the progression of advanced heart failure (HF) should be determined to establish strategies for its treatment or prevention. Based on pathological, molecular, and physiological findings in 3 animal models and human cases, we propose a novel scheme that a vicious cycle formed by increased sarcolemma (SL) permeability, preferential activation of calpain over calpastatin, and translocation and cleavage of dystrophin (Dys) commonly lead to advanced HF. The aim of this article was to assess our recent paradigm that disruption of myocardial Dys is a final common pathway to advanced HF, irrespective of its hereditary or acquired origin, but not intended to provide a comprehensive overview of the various factors that may be involved in the course of HF in different clinical settings. In addition, each component of Dys-associated proteins (DAP) was heterogeneously degraded in vivo and in vitro, i.e. Dys and alpha-sarcoglycan (SG) were markedly destroyed using isolated calpain 2, while delta-SG was not degraded at all. The up-regulation of calpain 2 was confirmed through previously published data that remain insufficient for precise evaluation, supporting our new scheme that the activation of calpain(s) is involved in the steady process of Dys cleavage. In addition, somatic gene therapy is discussed as a potential option to ameliorate the physiological/metabolic indices and to improve the prognosis.

Adeno-associated virus serotype 8 efficiently delivers genes to muscle and heart

Systemic gene delivery into muscle has been a major challenge for muscular dystrophy gene therapy, with capillary blood vessels posing the principle barrier and limiting vector dissemination. Previous efforts to deliver genes into multiple muscles have relied on isolated vessel perfusion or pharmacological interventions to enforce broad vector distribution. We compared the efficiency of multiple adeno-associated virus (AAV) vectors after a single injection via intraperitoneal or intravenous routes without additional intervention. We show that AAV8 is the most efficient vector for crossing the blood vessel barrier to attain systemic gene transfer in both skeletal and cardiac muscles of mice and hamsters. Serotypes such as AAV1 and AAV6, which demonstrate robust infection in skeletal muscle cells, were less effective in crossing the blood vessel barrier. Gene expression persisted in muscle and heart, but diminished in tissues undergoing rapid cell division, such as neonatal liver. This technology should prove useful for muscle-directed systemic gene therapy.

A novel scheme of dystrophin disruption for the progression of advanced heart failure

The precise mechanism of the progression of advanced heart failure is unknown. We assessed a new scheme in two heart failure models: (I) congenital dilated cardiomyopathy (DCM) in TO-2 strain hamsters lacking delta-sarcoglycan (SG) gene and (II) administration of a high-dose of isoproterenol, as an acute heart failure in normal rats. In TO-2 hamsters, we followed the time course of the histological, physiological and metabolic the progressions of heart failure to the end stage. Dystrophin localization detected by immunostaining age-dependently to the myoplasm and the in situ sarcolemma fragility evaluated by Evans blue entry was increased in the same cardiomyocytes. Western blotting revealed a limited cleavage of the dystrophin protein at the rod domain, strongly suggesting a contribution of endogenous protease(s). We found a remarkable up-regulation of the amount of calpain-1 and -2, and no change of their counterpart, calpastatin. After supplementing TO-2 hearts with the normal delta-SG gene in vivo, these pathological alterations and the animals' survival improved. Furthermore, dystrophin but not delta-SG was disrupted by a high dose of isoproterenol, translocated from the sarcolemma to the myoplasm and fragmented. These results of heart failure, irrespective of the hereditary or acquired origin, indicate a vicious cycle formed by the increased sarcolemma permeability, preferential activation of calpain over calpastatin, and translocation and cleavage of dystrophin would commonly lead to advanced 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.