Ser194Leu DSG2 mutation, associated with arrhythmogenic left ventricular cardiomyopathy and ventricular tachycardia

INTRODUCTION

Arrhythmogenic cardiomyopathy (AC) is an inherited cardiomyopathy characterized by fibro-fatty replacement of cardiomyocytes, leading to life-threatening ventricular arrhythmia and heart failure. Pathogenic variants of desmoglein2 gene (DSG2) have been reported as genetic etiologies of AC. In contrast, many reported DSG2 variants are benign or variants of uncertain significance. Correct genetic variant classification is crucial for determining the best medical therapy for the patient and family members.

METHODS

Pathogenicity of the DSG2 Ser194Leu variant that was identified by whole exome sequencing in a patient, who presented with ventricular tachycardia and was diagnosed with AC, was investigated by electron microscopy and immunohistochemical staining of endomyocardial biopsy sample.

RESULTS

Electron microscopy demonstrated a widened gap in the adhering junction and a less well-organized intercalated disk region in the mutated cardiomyocytes compared to the control. Immunohistochemical staining in the proband diagnosed with AC showed reduced expression of desmoglein 2 and connexin 43 and intercalated disc distortion. Reduced expression of DSG2 and Connexin 43 were observed in cellular cytoplasm and gap junctions. Additionally, we detected perinuclear accumulation of DSG2 and Connexin 43 in the proband sample.

CONCLUSION

Ser194Leu is a missense pathogenic mutation of DSG2 gene associated with arrhythmogenic left ventricular cardiomyopathy.

Effects of ketone body 3-hydroxybutyrate on cardiac and mitochondrial function during donation after circulatory death heart transplantation

Normothermic regional perfusion (NRP) allows assessment of therapeutic interventions prior to donation after circulatory death transplantation. Sodium-3-hydroxybutyrate (3-OHB) increases cardiac output in heart failure patients and diminishes ischemia-reperfusion injury, presumably by improving mitochondrial metabolism. We investigated effects of 3-OHB on cardiac and mitochondrial function in transplanted hearts and in cardiac organoids. Donor pigs (n = 14) underwent circulatory death followed by NRP. Following static cold storage, hearts were transplanted into recipient pigs. 3-OHB or Ringer's acetate infusions were initiated during NRP and after transplantation. We evaluated hemodynamics and mitochondrial function. 3-OHB mediated effects on contractility, relaxation, calcium, and conduction were tested in cardiac organoids from human pluripotent stem cells. Following NRP, 3-OHB increased cardiac output (P < 0.0001) by increasing stroke volume (P = 0.006), dP/dt (P = 0.02) and reducing arterial elastance (P = 0.02). Following transplantation, infusion of 3-OHB maintained mitochondrial respiration (P = 0.009) but caused inotropy-resistant vasoplegia that prevented weaning. In cardiac organoids, 3-OHB increased contraction amplitude (P = 0.002) and shortened contraction duration (P = 0.013) without affecting calcium handling or conduction velocity. 3-OHB had beneficial cardiac effects and may have a potential to secure cardiac function during heart transplantation. Further studies are needed to optimize administration practice in donors and recipients and to validate the effect on mitochondrial function.

International Consensus on Differential Diagnosis and Management of Patients With Danon Disease: JACC State-of-the-Art Review

Danon disease is a rare X-linked autophagic vacuolar cardioskeletal myopathy associated with severe heart failure that can be accompanied with extracardiac neurologic, skeletal, and ophthalmologic manifestations. It is caused by loss of function variants in the LAMP2 gene and is among the most severe and penetrant of the genetic cardiomyopathies. Most patients with Danon disease will experience symptomatic heart failure. Male individuals generally present earlier than women and die of either heart failure or arrhythmia or receive a heart transplant by the third decade of life. Herein, the authors review the differential diagnosis of Danon disease, diagnostic criteria, natural history, management recommendations, and recent advances in treatment of this increasingly recognized and extremely morbid cardiomyopathy.

What drives performance in machine learning models for predicting heart failure outcome?

Aims

The development of acute heart failure (AHF) is a critical decision point in the natural history of the disease and carries a dismal prognosis. The lack of appropriate risk-stratification tools at hospital discharge of AHF patients significantly limits clinical ability to precisely tailor patient-specific therapeutic regimen at this pivotal juncture. Machine learning-based strategies may improve risk stratification by incorporating analysis of high-dimensional patient data with multiple covariates and novel prediction methodologies. In the current study, we aimed at evaluating the drivers for success in prediction models and establishing an institute-tailored artificial Intelligence-based prediction model for real-time decision support.

Methods and results

We used a cohort of all 10 868 patients AHF patients admitted to a tertiary hospital during a 12 years period. A total of 372 covariates were collected from admission to the end of the hospitalization. We assessed model performance across two axes: (i) type of prediction method and (ii) type and number of covariates. The primary outcome was 1-year survival from hospital discharge. For the model-type axis, we experimented with seven different methods: logistic regression (LR) with either L₁ or L₂ regularization, random forest (RF), Cox proportional hazards model (Cox), extreme gradient boosting (XGBoost), a deep neural-net (NeuralNet) and an ensemble classifier of all the above methods. We were able to achieve an area under receiver operator curve (AUROC) prediction accuracy of more than 80% with most prediction models including L1/L2-LR (80.4%/80.3%), Cox (80.2%), XGBoost (80.5%), NeuralNet (80.4%). RF was inferior to other methods (78.8%), and the ensemble model was slightly superior (81.2%). The number of covariates was a significant modifier (P < 0.001) of prediction success, the use of multiplex-covariates preformed significantly better (AUROC 80.4% for L1-LR) compared with a set of known clinical covariates (AUROC 77.8%). Demographics followed by lab-tests and administrative data resulted in the largest gain in model performance.

Conclusions

The choice of the predictive modelling method is secondary to the multiplicity and type of covariates for predicting AHF prognosis. The application of a structured data pre-processing combined with the use of multiple-covariates results in an accurate, institute-tailored risk prediction in AHF.

Safety, usability, and performance of a wireless left atrial pressure monitoring system in patients with heart failure: the VECTOR-HF trial

AIMS

In heart failure (HF), implantable hemodynamic monitoring devices have been shown to optimize therapy, anticipating clinical decompensation and preventing hospitalization. Direct left-sided hemodynamic sensors offer theoretical benefits beyond pulmonary artery pressure (PAP) monitoring systems. We evaluated the safety, usability, and performance of a novel left atrial pressure (LAP) monitoring system in HF patients.

METHODS AND RESULTS

The VECTOR-HF study(NCT03775161) was a first-in-human, prospective, multicenter, single-arm, clinical trial enrolling 30 patients with HF. The device consisted of an interatrial positioned leadless sensor, able to transmit LAP data wirelessly. After three months, a right heart catheterization (RHC) was performed to correlate mean pulmonary capillary wedge pressure (PCWP) with simultaneous mean LAP obtained from the device. Remote LAP measurements were then used to guide patient management. The miniaturized device was successfully implanted in all 30 patients, without acute Major Adverse Cardiac and Neurological Events (MACNE). At 3 months, freedom from short-term MACNE was 97%. Agreement between sensor-calculated LAP and PCWP was consistent, with a mean difference of -0.22±4.92mmHg, the correlation coefficient and the Lin's Concordance Correlation Coefficient values were equal to 0.79 (P<0.0001) and 0.776 (95%CI=0.582-0.886), respectively. Preliminary experience with VLAP-based HF management was associated with significant improvements in NYHA functional class (32% of patients reached NYHA II class at 6 months, P<0.005; 60% of patients at 12 months, P<0.005) and 6-minute walk-test distance (from 244.59±119.59m at baseline to 311.78±129.88m after 6 months, P<0.05, and 343.95±146.15m after 12 months, P<0.05).

CONCLUSION

The V-LAP™ monitoring system proved to be generally safe and provided a good correlation with invasive PCWP. Initial evidence also suggests possible improvement in HF clinical symptoms. This article is protected by copyright. All rights reserved.

The V-LAP System for Remote Left Atrial Pressure Monitoring of Patients with Heart Failure: Remote Left Atrial Pressure Monitoring

OBJECTIVE

Patients with heart failure (HF) are at an increased risk of hospital admissions. The aim of this report is to describe the feasibility, safety and accuracy of a novel wireless left atrial pressure (LAP) monitoring system in HF patients.

METHODS

The V-LAP Left Atrium Monitoring systEm for Patients With Chronic sysTOlic & Diastolic Congestive heart Failure (VECTOR-HF) study is a prospective, multicenter, single-arm, open-label, first-in human clinical trial to assess the safety, performance and usability of the V-LAP system (Vectorious Medical Technologies, Ltd) in NYHA Class III HF patients. The device was implanted in the inter-atrial septum via a percutaneous, trans-septal approach, guided by fluoroscopy and echocardiography. Primary endpoints included the successful deployment of the implant, ability to perform initial pressure measurements and safety outcomes.

RESULTS

To date, 24 patients were implanted with the LAP monitoring device. No device-related complications have occurred. LAP was reported accurately, agreeing well with wedge pressure at 3 months (Lin's CCC=0.850). After 6 months, NYHA class improved in 40% of the patients (95% CI =16.4%-63.5%), while 6-minute walk test distance had not changed significantly (313.9 ± 144.9 vs. 232.5 ± 129.9 meters, p=0.076).

CONCLUSION

The V-LAP left atrium monitoring system appears to be safe and accurate.

Literature Review and Knowledge Distribution During an Outbreak: A Methodology for Managing Infodemics

PROBLEM

The COVID-19 pandemic has challenged health care systems in an unprecedented way by imposing new demands on health care resources and scientific knowledge. There has also been an exceedingly fast accumulation of new information on this novel virus. As the traditional peer-review process takes time, there is currently a significant gap between the ability to generate new data and the ability to critically evaluate them. This problem of an excess of mixed-quality data, or infodemic, is echoing throughout the scientific community.

APPROACH

The authors aimed to help their colleagues at the Rambam Medical Center, Haifa, Israel, manage the COVID-19 infodemic with a methodologic solution: establishing an in-house mechanism for continuous literature review and knowledge distribution (March-April 2020). Their methodology included the following building blocks: a dedicated literature review team, artificial intelligence-based research algorithms, brief written updates in a graphical format, large-scale webinars and online meetings, and a feedback loop.

OUTCOMES

During the first month (April 2020), the project produced 21 graphical updates. After consideration of feedback from colleagues and final editing, 13 graphical updates were uploaded to the center's website; of these, 31% addressed the clinical presentation of the disease and 38% referred to specific treatments. This methodology as well as the graphical updates it generated were adopted by the Israeli Ministry of Health and distributed in a hospital preparation kit.

NEXT STEPS

The authors believe they have established a novel methodology that can assist in the battle against COVID-19 by making high-quality scientific data more accessible to clinicians. In the future, they expect this methodology to create a favorable uniform standard for evidence-guided health care during infodemics. Further evolution of the methodology may include evaluation of its long-term sustainability and impact on the day-to-day clinical practice and self-confidence of clinicians who treat COVID-19 patients.

Socioeconomic disparities and COVID-19 vaccination acceptance: a nationwide ecologic study

Objective

To analyse the correlation between COVID-19 vaccination percentage and socioeconomic status (SES).

Methods

A nationwide ecologic study based on open-sourced, anonymized, aggregated data provided by the Israel Ministry of Health. The correlations between municipal SES, vaccination percentage and active COVID-19 cases during the vaccination campaign were analysed by using weighted Pearson correlations. To assess the adequacy of first dose vaccination rollout relative to the municipality COVID-19 disease burden, a metric termed the vaccination need ratio was devised by dividing the total number of active cases (per 10 000 people) by the vaccination percentage of the population over 60 in each municipality, and its correlation with the SES was examined.

Results

23 days after initiation of the vaccination campaign, 760 916 (56.8%) individuals over the age of 60 were vaccinated in Israel with the first dose of the BNT162b2 COVID-19 vaccine. A negative correlation was found between the COVID-19 active case burden and the vaccination percentage of the study population in each municipality (r = –0.47, 95% CI –0.59 to –0.30). The vaccination percentage significantly correlated with the municipal SES (r = 0.83, 95% CI 0.79 to 0.87). This finding persisted but was attenuated over a 5-week period. A negative correlation between the vaccination need ratio and municipal SES (r = –0.80, 95% CI –0.88 to –0.66) was found.

Discussion

Lower COVID-19 vaccination percentage was associated with lower SES and high active disease burden. Vaccination efforts should focus on areas with lower SES and high disease burden to assure equality of vaccine allocation and potentially provide a more diligent disease mitigation.

What drives success in models predicting heart failure outcome?

Introduction

The development of acute heart failure (AHF) is a critical decision-point in the natural history of heart failure and carries a dismal prognosis. The lack of appropriate risk-stratification tools for AHF patients limits physician ability to precisely tailor patient-specific therapy regimen at this important juncture. Machine learning (ML) based strategies may enhance risk stratification by incorporating analysis of high-dimensional patient data with multiple covariates and novel prediction methodologies.

In this study, we aimed at evaluating the drivers for success in prediction models and establishing an institute-tailored ML-based prediction model for real-time decision support.

Methods

We used a cohort of all AHF patients admitted during a 12 years period including 10,868 patients. A total of 372 covariates were collected from admission to the end of the hospitalization (demographics, lab-tests, medical therapies, echocardiographic and administrative data). Data preprocessing included features cleaning, train-test split, imputation and normalization. We assessed model performance across two axes (1) type of prediction method and (2) type and number of covariates. The primary outcome was one-year survival from hospital discharge. For the model-type axis we experimented with seven different methods: Logistic Regression (LR), Random Forest (RF), Cox model (Cox), XGBoost, a deep neural-network (NeuralNet) and an ensembled model.

Results

Data pre-processing methodology combined with multiple-covariates achieved an out-ofsample AUROC prediction accuracy of more than 80% with almost all prediction models: L1/L2-LR (80.4%/80.3%); Cox (80.1%); XGBoost (80.7%); NeuralNet (80.5%). The number of covariates was a significant modifier of prediction success (p&lt;0.001), the use of multiple-covariates (372) performed better (AUROC 80.4% for L1-LR) compared with using only a set of known clinical covariates (AUROC 77.8%).

Conclusions

The choice of the predictive modeling method is secondary to the multiplicity and type of covariates for predicting AHF prognosis. The application of a structured data pre-processing combined with the use of multiple-covariates results in an accurate, institute-tailored, risk prediction in AHF.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Yad Hanadiv

Technological Developments and Strategic Management for Overcoming the COVID-19 Challenge within the Hospital Setting in Israel

The coronavirus disease 2019 (COVID-19) pandemic has remarkably challenged health care organizations and societies. A key strategy for confronting the disease implications on individuals and communities was based on harnessing multidisciplinary efforts to develop technologies for mitigating the disease spread and its deleterious clinical implications. One of the main challenging characteristics of COVID-19 is the provision of medical care to patients with a highly infective disease mandating the use of isolation measures. Such care is complicated by the need for complex critical care, dynamic treatment guidelines, and a vague knowledge regarding the disease's pathophysiology. A second key component of this challenge was the overwhelming surge in patient burden and the relative lack of trained staff and medical equipment which required rapid re-organization of large systems and augmenting health care efficiencies to unprecedented levels. In contrast to the risk management strategies employed to mitigate other serious threats and the billions of dollars that are invested in reducing these risks annually by governments around the world, no such preparation has been shown to be of effect during the current COVID-19 pandemic. Unmet needs were identified within the newly opened COVID-19 departments together with the urgent need for reliable information for effective decision-making at the state level.This review article describes the early research and development response in Israel under the scope of in-hospital patient care, such as non-contact sensing of patients' vital signs, and how it could potentially be weaved into a practical big picture at the hospital or national level using a strategic management system. At this stage, some of the described technologies are still in developmental or clinical evidence generation phases with respect to COVID-19 settings. While waiting for future publications describing the results of the ongoing evidence generation efforts, one should be aware of this trend as these emerging tools have the potential to further benefit patients as well as caregivers and health care systems beyond the scope of the current pandemic as well as confronting future surges in the number of cases.

Morphine in the Setting of Acute Heart Failure: Do the Risks Outweigh the Benefits?

The use of opioids in acute pulmonary oedema is considered standard therapy by many physicians. The immediate relieving effect of morphine on the key symptomatic discomfort associated with acute heart failure, dyspnoea, facilitated the categorisation of morphine as a beneficial treatment in this setting. During the last decade, several retrospective studies raised concerns regarding the safety and efficacy of morphine in the setting of acute heart failure. In this article, the physiological effects of morphine on the cardiovascular and respiratory systems are summarised, as well as the potential clinical benefits and risks associated with morphine therapy. Finally, the reported clinical outcomes and adverse event profiles from recent observational studies are discussed, as well as future perspectives and potential alternatives to morphine in the setting of acute heart failure.

Insights from the Third Dimension: Cardiac Organoids Help Identify Regenerative Pathways

In this issue of Cell Stem Cell, Mills et al. (2019) use multidimensional functional screening to identify pro-proliferative compounds in cell-cycle-arrested human cardiac organoids. Using this model, the authors identify two hit compounds that restart cardiomyocyte proliferation by synergistically activating the mevalonate pathway and cell-cycle-related pathways.

Adverse dose-dependent effects of morphine therapy in acute heart failure

BACKGROUND

Morphine has been a pivotal therapy in acute heart failure (AHF) for more than a century. The evidence for morphine therapy in AHF remains controversial. This study sought to assess the therapeutic effect of morphine on patients with AHF.

METHODS

The study used a cohort of 13,788 patients admitted with a primary diagnosis of AHF. Propensity-score-matching was generated using 26 clinical variables. Primary endpoints included in-hospital mortality and invasive mechanical ventilation. Secondary endpoints included non-invasive ventilation, need for inotropes and acute kidney injury (AKI).

RESULTS

761 (5.5%) patients were treated with morphine in the first day following hospital admission. Propensity score matching yielded 672 patient pairs. The incidence of invasive ventilation was higher in the morphine-treated patients (7.4%) than in matched patients in the no-morphine cohort (3.6%), OR 2.13 (95% CI 1.32-3.57, P = 0.007). In-hospital mortality was also higher in the morphine group (17.4%) than in the matched no-morphine group (13.4%), OR 1.43 (95% CI 1.05 to 1.98, P = 0.024). For both the endpoint of invasive ventilation (P_trend = 0.005) and mortality (P_trend = 0.004), there was a significant linear dose-response relationship for the adverse effect of morphine. Morphine was associated with a significant increase in all secondary outcomes: Non-invasive ventilation (OR 2.78, 95% CI 1.95-3.96); Inotrope use (OR 3.50, 95% CI 2.10-5.82) and AKI (OR 1.81, 95% CI 1.39-2.36). A landmark analysis demonstrated no difference in post-discharge survival between cohorts.

CONCLUSIONS

Morphine administration is associated with significant dose-dependent risk for in-hospital mortality and need for mechanical ventilation.

Surviving Cancer without a Broken Heart

Chemotherapy-associated myocardial toxicity is increasingly recognized with the expanding armamentarium of novel chemotherapeutic agents. The onset of cardiotoxicity during cancer therapy represents a major concern and often involves clinical uncertainties and complex therapeutic decisions, reflecting a compromise between potential benefits and harm. Furthermore, the improved cancer survival has led to cardiovascular complications becoming clinically relevant, potentially contributing to premature morbidity and mortality among cancer survivors. Specific higher-risk populations of cancer patients can benefit from prevention and screening measures during the course of cancer therapies. The pathobiology of chemotherapy-induced myocardial dysfunction is complex, and the individual patient risk for heart failure entails a multifactorial interaction between the selected chemotherapeutic regimen, traditional cardiovascular risk factors, and individual susceptibility. Treatment with several specific chemotherapeutic agents, including anthracyclines, proteasome inhibitors, epidermal growth factor receptor inhibitors, vascular endothelial growth factor inhibitors, and immune checkpoint inhibitors imparts increased risk for cardiotoxicity that results from specific therapy-related mechanisms. We review the pathophysiology, risk factors, and imaging considerations as well as patient surveillance, prevention, and treatment approaches to mitigate cardiotoxicity prior, during, and after chemotherapy. The complexity of decision-making in these patients requires viable discussion and partnership between cardiologists and oncologists aiming together to eradicate cancer while preventing cardiotoxic sequelae.

Danon disease: Gender differences in presentation and outcomes

BACKGROUND

Danon disease (DD) is a rare X-linked autophagic vacuolar myopathy, characterized by high penetrance and severe cardiomyopathy. Because of its rarity, the natural history (NH) is uncertain.

OBJECTIVES

We aimed to describe disease variability and outcomes through a systematic review of all published DD cases.

METHODS

Among 83 manuscripts in MEDLINE and EMBASE on DD cases published until October 2017, we identified 146 patients with positive genetic testing for DD or positive muscle biopsy in a relative of a genetically diagnosed proband.

RESULTS

56 females and 90 males were identified. 92.5% of patients had cardiac abnormalities. Females presented with either hypertrophic cardiomyopathy (HCM, 70.3%) or dilated cardiomyopathy (DCM, 29.3%) whereas males presented with HCM 96.2% of the time. The composite outcome of death, heart transplant or ventricular assist devices occurred equally in both sexes (32% of females and 37% of males, p = 0.60) but later in females (median age 38 years) than in males (median age 21 years, p < 0.001). Whereas women present with isolated cardiac disease 73% of the time, in males DD was frequently multisystemic and presented as a triad of cognitive impairment, skeletal myopathy, and HCM in 42% of patients.

CONCLUSIONS

In this first systematic review of DD, we confirmed the severe morbidity and mortality associated with disease in both sexes. Women presented with both HCM and DCM and generally with isolated cardiac disease, whereas in men DD usually presented as HCM and was frequently multi-systemic. Further prospective NH studies will be required to confirm these findings.

Acute Kidney Injury After Primary Angioplasty: Is Contrast-Induced Nephropathy the Culprit?

Background

Acute kidney injury (AKI) following primary percutaneous coronary intervention (pPCI) is frequently interpreted as contrast‐induced AKI but may result from other insults. We aimed to determine the causal association of contrast material exposure and the incidence of AKI following pPCI using a control group of propensity score–matched patients with ST‐segment–elevation myocardial infarction who were not exposed to contrast material.

Methods and Results

We studied 2025 patients with ST‐segment–elevation myocardial infarction who underwent pPCI and 1025 patients receiving fibrinolysis or no reperfusion who were not exposed to contrast material during the first 72 hours of hospital stay (control group). AKI was defined as creatinine of ≥0.5 mg/dL or >25% rise within 72 hours. AKI rates were similar in the pPCI and control groups (10.3% versus 12.1%, respectively; P=0.38). Propensity score matching resulted in 931 matched pairs with PCI and no PCI, with balanced baseline covariates (standardized difference <0.1). Among propensity score–matched patients, AKI rates were not significantly different with and without PCI (8.6% versus 10.9%, P=0.12). In the pPCI cohort, independent predictors of AKI included age ≥70 years, insulin‐treated diabetes mellitus, diuretic therapy, anterior infarction, baseline estimated glomerular filtration rate, and variables related to the presence of pump failure (higher Killip class, intra‐aortic balloon pump use) and reduced left ventricular ejection fraction but not contrast material dose. A risk score based on the PCI cohort had similar discriminatory capacity for AKI in the control group (C statistic 0.81±0.02 and 0.78±0.02, respectively; P=0.26).

Conclusions

The development of AKI in patients with ST‐segment–elevation myocardial infarction undergoing pPCI is mainly related to older age, baseline estimated glomerular filtration rate, heart failure, and hemodynamic instability. Risk for AKI is similar among ST‐segment–elevation myocardial infarction patients with and without contrast material exposure.

Modeling of arrhythmogenic right ventricular cardiomyopathy with human induced pluripotent stem cells

BACKGROUND

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disorder resulting from desmosomal protein mutations. ARVC is characterized pathologically by fibrofatty infiltration and clinically by arrhythmias and sudden cardiac death. We aimed to establish a patient-/disease-specific human induced pluripotent stem cell (hiPSC) model of ARVC.

METHODS AND RESULTS

Dermal fibroblasts were obtained from 2 patients with ARVC with plakophilin-2 (PKP2) mutations, reprogrammed to generate hiPSCs, coaxed to differentiate into cardiomyocytes (CMs), and then compared with healthy control hiPSC-derived CMs (hiPSC-CMs). Real-time polymerase chain reaction showed a significant decrease in the expression of PKP2 in the ARVC-hiPSC-CMs. Immunostainings revealed reduced densities of PKP2, the associated desmosomal protein plakoglobin, and the gap-junction protein connexin-43. Electrophysiological assessment demonstrated prolonged field potential rise time in the ARVC-hiPSC-CMs. Transmission electron microscopy identified widened and distorted desmosomes in the ARVC-hiPSC-CMs. Clusters of lipid droplets were identified in the ARVC-CMs that displayed the more severe desmosomal pathology. This finding was associated with upregulation of the proadipogenic transcription factor peroxisome proliferator-activated receptor-γ. Exposure of the cells to apidogenic stimuli augmented desmosomal distortion and lipid accumulation. The latter phenomenon was prevented by application of a specific inhibitor of glycogen synthase kinase 3β (6-bromoindirubin-3'-oxime).

CONCLUSIONS

This study highlights the unique potential of the hiPSC technology for modeling inherited cardiac disorders in general and ARVC specifically. The hiPSC-CMs were demonstrated to recapitulate the ARVC phenotype in the dish, provide mechanistic insights into early disease pathogenesis, and provide a unique platform for drug discovery and testing in this disorder.

Modeling of catecholaminergic polymorphic ventricular tachycardia with patient-specific human-induced pluripotent stem cells

OBJECTIVES

The goal of this study was to establish a patient-specific human-induced pluripotent stem cells (hiPSCs) model of catecholaminergic polymorphic ventricular tachycardia (CPVT).

BACKGROUND

CPVT is a familial arrhythmogenic syndrome characterized by abnormal calcium (Ca(2+)) handling, ventricular arrhythmias, and sudden cardiac death.

METHODS

Dermal fibroblasts were obtained from a CPVT patient due to the M4109R heterozygous point RYR2 mutation and reprogrammed to generate the CPVT-hiPSCs. The patient-specific hiPSCs were coaxed to differentiate into the cardiac lineage and compared with healthy control hiPSCs-derived cardiomyocytes (hiPSCs-CMs).

RESULTS

Intracellular electrophysiological recordings demonstrated the development of delayed afterdepolarizations in 69% of the CPVT-hiPSCs-CMs compared with 11% in healthy control cardiomyocytes. Adrenergic stimulation by isoproterenol (1 μM) or forskolin (5 μM) increased the frequency and magnitude of afterdepolarizations and also led to development of triggered activity in the CPVT-hiPSCs-CMs. In contrast, flecainide (10 μM) and thapsigargin (10 μM) eliminated all afterdepolarizations in these cells. The latter finding suggests an important role for internal Ca(2+) stores in the pathogenesis of delayed afterdepolarizations. Laser-confocal Ca(2+) imaging revealed significant whole-cell [Ca(2+)] transient irregularities (frequent local and large-storage Ca(2+)-release events, broad and double-humped transients, and triggered activity) in the CPVT cardiomyocytes that worsened with adrenergic stimulation and Ca(2+) overload and improved with beta-blockers. Store-overload-induced Ca(2+) release was also identified in the hiPSCs-CMs and the threshold for such events was significantly reduced in the CPVT cells.

CONCLUSIONS

This study highlights the potential of hiPSCs for studying inherited arrhythmogenic syndromes, in general, and CPVT specifically. As such, it represents a promising paradigm to study disease mechanisms, optimize patient care, and aid in the development of new therapies.

A combined cell therapy and in-situ tissue-engineering approach for myocardial repair

Myocardial cell-replacement strategies are hampered by limited sources for human cardiomyocytes and by significant cell loss following transplantation. We tested the hypothesis that a combined delivery of cardiomyocytes with an in-situ polymerizable hydrogel into a post-MI rat heart will result in better functional outcomes than each intervention alone. A photopolymerizable, biodegradable, PEGylated-fibrinogen (PF) hydrogel matrix was used as the carrier for the cardiomyocytes [neonatal rat ventricular cardiomyocytes (NRVCMs) or human embryonic stem cell-derived cardiomyocytes (hESC-CMs)]. Infarcted rat hearts (LAD ligation) were randomized to injection of saline, NRVCMs, biopolymer, or combined biopolymer-cell delivery. Echocardiography revealed typical post-infarction remodeling after 30 days in the saline-injected control group [deterioration of fractional shortening (FS) by 31.0 ± 3.6%]. Injection of NRVCMs or PF alone significantly (p < 0.01) altered this remodeling process (slightly increasing FS by 3.1 ± 6.6% and 0.5 ± 5.3% respectively). Co-injection of the NRVCMs with PF matrix resulted in a significant increase in the cell-graft area (by 144%) and in the highest improvements in FS (by 26.3 ± 6.6%). Finally, feasibility studies were performed with the PF matrix and hESC-CMs. We conclude that an injectable in-situ forming hydrogel can act as a cardiomyocyte cell-carrier and add to the beneficial effects of the grafted cells in preventing unfavorable post-infarction cardiac remodeling.

In vivo assessment of the electrophysiological integration and arrhythmogenic risk of myocardial cell transplantation strategies

Cell replacement strategies are promising interventions aiming to improve myocardial performance. Yet, the electrophysiological impact of these approaches has not been elucidated. We assessed the electrophysiological consequences of grafting of two candidate cell types, that is, skeletal myoblasts and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). The fluorescently labeled (DiO) candidate cells were grafted into the rat's left ventricular myocardium. Two weeks later, optical mapping was performed using the Langendorff-perfused rat heart preparation. Images were obtained with appropriate filters to delineate the heart's anatomy, to identify the DiO-labeled cells, and to associate this information with the voltage-mapping data (using the voltage-sensitive dye PGH-I). Histological examination revealed the lack of gap junctions between grafted skeletal myotubes and host cardiomyocytes. In contrast, positive Cx43 immunostaining was observed between donor and host cardiomyocytes in the hESC-CMs-transplanted hearts. Optical mapping demonstrated either normal conduction (four of six) or minimal conduction slowing (two of six) at the hESC-CMs engraftment sites. In contrast, marked slowing of conduction or conduction block was seen (seven of eight) at the myoblast transplantation sites. Ventricular arrhythmias could not be induced in the hESC-CM hearts following programmed electrical stimulation but were inducible in 50% of the myoblast-engrafted hearts. In summary, a unique method for assessment of the electrophysiological impact of myocardial cell therapy is presented. Our results demonstrate the ability of hESC-CMs to functionally integrate with host tissue. In contrast, transplantation of cells that do not form gap junctions (skeletal myoblats) led to localized conduction disturbances and to the generation of a proarrhythmogenic substrate.

Transplantation of a tissue-engineered human vascularized cardiac muscle

Myocardial regeneration strategies have been hampered by the lack of sources for human cardiomyocytes (CMs) and by the significant donor cell loss following transplantation. We assessed the ability of a three-dimensional tissue-engineered human vascularized cardiac muscle to engraft in the in vivo rat heart and to promote functional vascularization. Human embryonic stem cell-derived CMs alone or with human endothelial cells (human umbilical vein endothelial cells) and embryonic fibroblasts (triculture constructs) were seeded onto biodegradable porous scaffolds. The resulting tissue constructs were transplanted to the in vivo rat heart and formed cardiac tissue grafts. Immunostaining studies for human-specific CD31 and alpha-smooth muscle actin demonstrated the formation of both donor (human) and host (rat)-derived vasculature within the engrafted triculture tissue constructs. Intraventricular injection of fluorescent microspheres or lectin resulted in their incorporation by human-derived vessels, confirming their functional integration with host coronary vasculature. Finally, the number of blood vessels was significantly greater in the triculture tissue constructs (60.3 +/- 8/mm(3), p < 0.05) when compared with scaffolds containing only CMs (39.0 +/- 14.4/mm(3)). In conclusion, a tissue-engineered human vascularized cardiac muscle can be established ex vivo and transplanted in vivo to form stable grafts. By utilizing a multicellular preparation we were able to increase biograft vascularization and to show that the preexisting human vessels can become functional and contribute to tissue perfusion.

Methods for human embryonic stem cells derived cardiomyocytes cultivation, genetic manipulation, and transplantation

A decade has passed since the initial derivation of human embryonic stem cells (hESC). The ensuing years have witnessed a significant progress in the development of methodologies allowing cell cultivation, differentiation, genetic manipulation, and in vivo transplantation. Specifically, the potential to derive human cardiomyocytes from the hESC lines, which can be used for several basic and applied cardiovascular research areas including in the emerging field of cardiac regenerative medicine, attracted significant attention from the scientific community. This resulted in the development of protocols for the cultivation of hESC and their successful differentiation toward the cardiomyocyte lineage fate. In this chapter, we will describe in detail methods related to the cultivation, genetic manipulation, selection, and in vivo transplantation of hESC-derived cardiomyocytes.

Cardiomyocyte differentiation of human induced pluripotent stem cells

BACKGROUND

The ability to derive human induced pluripotent stem (hiPS) cell lines by reprogramming of adult fibroblasts with a set of transcription factors offers unique opportunities for basic and translational cardiovascular research. In the present study, we aimed to characterize the cardiomyocyte differentiation potential of hiPS cells and to study the molecular, structural, and functional properties of the generated hiPS-derived cardiomyocytes.

METHODS AND RESULTS

Cardiomyocyte differentiation of the hiPS cells was induced with the embryoid body differentiation system. Gene expression studies demonstrated that the cardiomyocyte differentiation process of the hiPS cells was characterized by an initial increase in mesoderm and cardiomesoderm markers, followed by expression of cardiac-specific transcription factors and finally by cardiac-specific structural genes. Cells in the contracting embryoid bodies were stained positively for cardiac troponin-I, sarcomeric alpha-actinin, and connexin-43. Reverse-transcription polymerase chain reaction studies demonstrated the expression of cardiac-specific sarcomeric proteins and ion channels. Multielectrode array recordings established the development of a functional syncytium with stable pacemaker activity and action potential propagation. Positive and negative chronotropic responses were induced by application of isoproterenol and carbamylcholine, respectively. Administration of quinidine, E4031 (I(Kr) blocker), and chromanol 293B (I(Ks) blocker) significantly affected repolarization, as manifested by prolongation of the local field potential duration.

CONCLUSIONS

hiPS cells can differentiate into myocytes with cardiac-specific molecular, structural, and functional properties. These results, coupled with the potential of this technology to generate patient-specific hiPS lines, hold great promise for the development of in vitro models of cardiac genetic disorders, for drug discovery and testing, and for the emerging field of cardiovascular regenerative medicine.

Human embryonic stem cells for cardiomyogenesis

Myocardial cell replacement strategies are emerging as novel therapeutic paradigms for heart failure but are hampered by the paucity of sources for human cardiomyocytes. Human embryonic stem cells (hESC) are pluripotent stem cell lines derived from human blastocysts that can be propagated, in culture, in the undifferentiated state under special conditions and coaxed to differentiate into cell derivatives of all three germ layers, including cardiomyocytes. The current review describes the derivation and properties of the hESC lines and the different cardiomyocyte differentiation system established so far using these cells. Data regarding the structural, molecular, and functional properties of the hESC-derived cardiomyocytes is provided as well as description of the methods used to achieve cardiomyocyte enrichment and purification in this system. The possible applications of this unique differentiation system in several cardiovascular research and applied areas are discussed. Specific emphasis is put on the descriptions of the efforts performed to date to assess the feasibility of this emerging technology in the fields of cardiac cell replacement therapy and tissue engineering. Finally, the obstacles remaining on the road to clinical translation are described as well as the steps required to fully harness the potential of this new technology.

Identification and selection of cardiomyocytes during human embryonic stem cell differentiation

Human embryonic stem cells (hESC) are pluripotent lines that can differentiate in vitro into cell derivatives of all three germ layers, including cardiomyocytes. Successful application of these unique cells in the areas of cardiovascular research and regenerative medicine has been hampered by difficulties in identifying and selecting specific cardiac progenitor cells from the mixed population of differentiating cells. We report the generation of stable transgenic hESC lines, using lentiviral vectors, and single-cell clones that express a reporter gene (eGFP) under the transcriptional control of a cardiac-specific promoter (the human myosin light chain-2V promoter). Our results demonstrate the appearance of eGFP-expressing cells during the differentiation of the hESC as embryoid bodies (EBs) that can be identified and sorted using FACS (purity>95%, viability>85%). The eGFP-expressing cells were stained positively for cardiac-specific proteins (>93%), expressed cardiac-specific genes, displayed cardiac-specific action-potentials, and could form stable myocardial cell grafts following in vivo cell transplantation. The generation of these transgenic hESC lines may be used to identify and study early cardiac precursors for developmental studies, to robustly quantify the extent of cardiomyocyte differentiation, to label the cells for in vivo grafting, and to allow derivation of purified cell populations of cardiomyocytes for future myocardial cell therapy strategies.

Tissue engineering of vascularized cardiac muscle from human embryonic stem cells

Transplantation of a tissue-engineered heart muscle represents a novel experimental therapeutic paradigm for myocardial diseases. However, this strategy has been hampered by the lack of sources for human cardiomyocytes and by the scarce vasculature in the ischemic area limiting the engraftment and survival of the transplanted muscle. Beyond the necessity of endothelial capillaries for the delivery of oxygen and nutrients to the grafted muscle tissue, interactions between endothelial and cardiomyocyte cells may also play a key role in promoting cell survival and proliferation. In the present study, we describe the formation of synchronously contracting engineered human cardiac tissue derived from human embryonic stem cells containing endothelial vessel networks. The 3D muscle consisted of cardiomyocytes, endothelial cells (ECs), and embryonic fibroblasts (EmFs). The formed vessels were further stabilized by the presence of mural cells originating from the EmFs. The presence of EmFs decreased EC death and increased EC proliferation. Moreover, the presence of endothelial capillaries augmented cardiomyocyte proliferation and did not hamper cardiomyocyte orientation and alignment. Immunostaining, ultrastructural analysis (using transmission electron microscopy), RT-PCR, pharmacological, and confocal laser calcium imaging studies demonstrated the presence of cardiac-specific molecular, ultrastructural, and functional properties of the generated tissue constructs with synchronous activity mediated by action potential propagation through gap junctions. In summary, this is the first report of the construction of 3D vascularized human cardiac tissue that may have unique applications for studies of cardiac development, function, and tissue replacement therapy.

Regenerating the heart using human embryonic stem cells--from cell to bedside

The adult human heart has limited regenerative capacity and, therefore, functional restoration of the damaged heart presents a great challenge. Despite the progress achieved in the pharmacological and surgical treatment of degenerative myocardial diseases, they are still considered a major cause of morbidity and mortality in the western world. Repopulation of the damaged heart with cardiomyocytes represents a novel conceptual therapeutic paradigm but is hampered by the lack of sources for human cardiomyocytes. The recent derivation of pluripotent human embryonic stem cell lines may provide a solution for this cell sourcing problem. This review will focus on the derivation of the hESC lines, their mechanism of self-renewal, and their differentiation to cardiomyocytes. The possible signals and cues involved in the commitment and early differentiation of cardiomyocytes in this model will be discussed as well as the molecular, structural and electrophysiologic characteristics of the generated hESC-derived cardiomyocytes. Finally, the hurdles and challenges toward fully harnessing the potential clinical applications of these unique cells will be described.

Electromechanical integration of cardiomyocytes derived from human embryonic stem cells

Cell therapy is emerging as a promising strategy for myocardial repair. This approach is hampered, however, by the lack of sources for human cardiac tissue and by the absence of direct evidence for functional integration of donor cells into host tissues. Here we investigate whether cells derived from human embryonic stem (hES) cells can restore myocardial electromechanical properties. Cardiomyocyte cell grafts were generated from hES cells in vitro using the embryoid body differentiating system. This tissue formed structural and electromechanical connections with cultured rat cardiomyocytes. In vivo integration was shown in a large-animal model of slow heart rate. The transplanted hES cell-derived cardiomyocytes paced the hearts of swine with complete atrioventricular block, as assessed by detailed three-dimensional electrophysiological mapping and histopathological examination. These results demonstrate the potential of hES-cell cardiomyocytes to act as a rate-responsive biological pacemaker and for future myocardial regeneration strategies.

Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes

Human embryonic stem cell-derived cardiomyocytes (hES-CMs) are thought to recapitulate the embryonic development of heart cells. Given the exciting potential of hES-CMs as replacement tissue in diseased hearts, we investigated the pharmacological sensitivity and ionic current of mid-stage hES-CMs (20-35 days post plating). A high-resolution microelectrode array was used to assess conduction in multicellular preparations of hES-CMs in spontaneously contracting embryoid bodies (EBs). TTX (10 microm) dramatically slowed conduction velocity from 5.1 to 3.2 cm s(-1) while 100 microm TTX caused complete cessation of spontaneous electrical activity in all EBs studied. In contrast, the Ca2+channel blockers nifedipine or diltiazem (1 microm) had a negligible effect on conduction. These results suggested a prominent Na+ channel current, and therefore we patch-clamped isolated cells to record Na+ current and action potentials (APs). We found for isolated hES-CMs a prominent Na+ current (244 +/- 42 pA pF(-1) at 0 mV; n=19), and a hyperpolarization-activated current (HCN), but no inward rectifier K+ current. In cell clusters, 3 microm TTX induced longer AP interpulse intervals and 10 microm TTX caused cessation of spontaneous APs. In contrast nifedipine (Ca2+ channel block) and 2 mm Cs+ (HCN complete block) induced shorter AP interpulse intervals. In single cells, APs stimulated by current pulses had a maximum upstroke velocity (dV/dtmax) of 118 +/- 14 V s(-1) in control conditions; in contrast, partial block of Na+ current significantly reduced stimulated dV/dtmax (38 +/- 15 V s(-1)). RT-PCR revealed NaV1.5, CaV1.2, and HCN-2 expression but we could not detect Kir2.1. We conclude that hES-CMs at mid-range development express prominent Na+ current. The absence of background K+ current creates conditions for spontaneous activity that is sensitive to TTX in the same range of partial block of NaV1.5; thus, the NaV1.5 Na+ channel is important for initiating spontaneous excitability in hES-derived heart cells.

Potential Applications of Human Embryonic Stem Cell-Derived Cardiomyocytes

The recent establishment of the human embryonic stem cell lines and the demonstration of their ability to differentiate in vitro to cardiomyocytes brings a unique promise to both basic and clinical research. The present report describes the characteristics of the human embryonic stem cell lines and focuses on the structural and functional properties of their cardiomyocyte derivatives. In addition, the possible signals and cues involved in the commitment and early differentiation of cardiomyocytes will be discussed. Finally, the potential applications of this unique differentiating system in several research and clinical areas are discussed, with special emphasis on the steps required to fully harness their potential for myocardial regeneration strategies.

Integrity and research: introducing the concept of dual blindness. how blind are double-blind clinical trials in alternative medicine?

Double-blind methodology is used in clinical studies to control for potential external or nonspecific influences such as belief and expectation, as well as to maintain as much objectivity as possible on the part of the researchers. Despite not being feasible in all medical disciplines, as in the case of some modalities of complementary and alternative medicine, there are numerous studies that spuriously claim its use. Distinctions and standards therefore need to be set to avoid misleading information. We propose a new term in research methodology, dual-blind, to describe a methodological alternative in which the caregiver is not blind but the patient and an external evaluator/investigator are. The term double-blind should be used strictly to describe a methodology in which both the patient and the caregiver are blind. Making the distinction between these two terms will result in more reliable reports of clinical trials and will support integrity in research.

Gastric-Mucocutaneous gammadelta T cell lymphoma: possible association with Epstein-Barr virus?

Gammadelta T cell lymphoma is usually either subcutaneous or hepato-splenic and involvement of other extranodal sites is rare. Here we report an unusual case of gammadelta T cell lymphoma involving the subcutaneous tissue, vocal cords, gastric mucosa and the central nervous system with a rapidly progressive clinical course and fatal outcome. Epstein-Barr virus (EBV) was shown to be present in the tumor cells, and is thought to play a role in the pathophysiology of this particular case of lymphoma.

Hepatobiliary graft-versus-host disease manifested by common and hepatic biliary duct obstruction

BACKGROUND

A 26-year-old patient presented with ascending cholangitis 8 months after allogeneic bone marrow transplantation for immunoblastic lymphoma.

METHODS AND RESULTS

Endoscopic retrograde cholangiopancreatography showed common and hepatic biliary duct obstruction that was attibuted to chronic graft-versus-host disease.

CONCLUSION

This case indicates that hepatobiliary disease related to chronic graft-versus-host disease may involve major bile ducts causing obstruction.

Digoxin intoxication in a patient with end-stage renal disease: efficacy of digoxin-specific Fab antibody fragments and peritoneal dialysis

Digoxin intoxication is a serious medical problem, and impairment of renal function is a common risk factor for toxicity. Digoxin specific antibody fragments (Fab) is the most effective treatment available for severe digitalis intoxication. The use of Fab therapy in a patient with renal disease is considered as effective as in patients with normal renal function, although the increased risk of rebound digoxin toxicity mandates a longer period of observation. In patients with kidney failure, neither digoxin nor Fab can be removed efficiently from the systemic circulation by hemodialysis or continuous arteriovenous hemofiltration. Knowledge about the clearance of both compounds by peritoneal dialysis is limited. The authors describe a patient with end stage renal disease who was treated with Fab and peritoneal dialysis for life threatening digoxin intoxication. Like other forms of dialysis, peritoneal dialysis, even when performed in an intensive schedule, is not associated with an enhanced clearance of digoxin.

Microsatellite instability and p53 mutations in therapy-related leukemia suggest mutator phenotype

During the last decade the frequency of therapy-related acute leukemia (t-leuk) and myelodysplastic syndrome (t-MDS) has been increasingly observed. Over the past 15 years, we treated 56 patients with t-leuk who had received prior chemotherapy (39%), radiotherapy (11%), or both (45%). The drugs received included alkylating agents and topoisomerase II inhibitors. The primary tumors included hematological malignancies (49%) and solid tumors such as breast or ovarian cancer. The median age at diagnosis of the primary tumor was relatively young (43 years +/- 18). Twelve patients had more than one primary tumor and 31 patients had a family history of malignancy. Karyotypic abnormalities were found in 91% of the patients. Prognosis was uniformly poor, with an overall median survival of 10 months. Twelve of the 18 patients examined (67%) had a multidrug resistance phenotype. P53 genes of the leukemic cells, as well as the original tumors, were analyzed in 21 patients using polymerase chain reaction (PCR) with single-stranded conformation polymorphism analysis followed by sequencing. P53 mutations were identified in 38% of these patients, a relatively high prevalence compared with other forms of MDS or de novo acute myeloid leukemia. Mutations were nongermline and restricted to the leukemic cells. We identified different p53 mutations in the various primary tumors of individual patients. The presence of a mutator phenotype was assessed by PCR analysis of microsatellites in eight loci (one trinucleotide repeat sequence, four dinucleotide, and three mononuclear repeat sequences). Microsatellite instability in two to seven loci were found in 15 of 16 (94%) of the patients. This instability is compatible with a mutator phenotype, which predisposes the patients to the development of malignancies including t-leuk.