The Netherlands Heart Tissue Bank : Strengthening the cardiovascular research infrastructure with an open access Cardiac Tissue Repository.

AIM: Cardiac diseases remain a leading cause of cardiovascular disease (CVD) related hospitalisation and mortality. That is why research to improve our understanding of pathophysiological processes underlying cardiac diseases is of great importance. There is a strong need for healthy and diseased human cardiac tissue and related clinical data to accomplish this, since currently used animal and in vitro disease models do not fully grasp the pathophysiological processes observed in humans. This design paper describes the initiative of the Netherlands Heart Tissue Bank (NHTB) that aims to boost CVD-related research by providing an open-access biobank. METHODS: The NHTB, founded in June 2020, is a non-profit biobank that collects and stores biomaterial (including but not limited to myocardial tissue and blood samples) and clinical data of individuals with and without previously known cardiac diseases. All individuals aged ≥ 18 years living in the Netherlands are eligible for inclusion as a potential future donor. The stored samples and clinical data will be available upon request for cardiovascular researchers. CONCLUSION: To improve the availability of cardiac tissue for cardiovascular research, the NHTB will include extensive (cardiac) biosamples, medical images, and clinical data of donors with and without a previously known cardiac disease. As such, the NHTB will function as a translational bridge to boost a wide range of cardiac disease-related fundamental and translational studies.

Rationale and design of the PHOspholamban RElated CArdiomyopathy intervention STudy (i-PHORECAST).

BACKGROUND: The p.Arg14del (c.40_42delAGA) phospholamban (PLN) pathogenic variant is a founder mutation that causes dilated cardiomyopathy (DCM) and arrhythmogenic cardiomyopathy (ACM). Carriers are at increased risk of malignant ventricular arrhythmias and heart failure, which has been ascribed to cardiac fibrosis. Importantly, cardiac fibrosis appears to be an early feature of the disease, occurring in many presymptomatic carriers before the onset of overt disease. As with most monogenic cardiomyopathies, no evidence-based treatment is available for presymptomatic carriers. AIMS: The PHOspholamban RElated CArdiomyopathy intervention STudy (iPHORECAST) is designed to demonstrate that pre-emptive treatment of presymptomatic PLN p.Arg14del carriers using eplerenone, a mineralocorticoid receptor antagonist with established antifibrotic effects, can reduce disease progression and postpone the onset of overt disease. METHODS: iPHORECAST has a multicentre, prospective, randomised, open-label, blinded endpoint (PROBE) design. Presymptomatic PLN p.Arg14del carriers are randomised to receive either 50 mg eplerenone once daily or no treatment. The primary endpoint of the study is a multiparametric assessment of disease progression including cardiac magnetic resonance parameters (left and right ventricular volumes, systolic function and fibrosis), electrocardiographic parameters (QRS voltage, ventricular ectopy), signs and/or symptoms related to DCM and ACM, and cardiovascular death. The follow-up duration is set at 3 years. BASELINE RESULTS: A total of 84 presymptomatic PLN p.Arg14del carriers (n = 42 per group) were included. By design, at baseline, all participants were in New York Heart Association (NHYA) class I and had a left ventricular ejection fraction > 45% and < 2500 ventricular premature contractions during 24-hour Holter monitoring. There were no statistically significant differences between the two groups in any of the baseline characteristics. The study is currently well underway, with the last participants expected to finish in 2021. CONCLUSION: iPHORECAST is a multicentre, prospective randomised controlled trial designed to address whether pre-emptive treatment of PLN p.Arg14del carriers with eplerenone can prevent or delay the onset of cardiomyopathy. iPHORECAST has been registered in the clinicaltrials.gov-register (number: NCT01857856).

Strength of patient cohorts and biobanks for cardiomyopathy research.

In 2011 the Netherlands Heart Foundation allocated funding (CVON, Cardiovasculair Onderzoek Nederland) to stimulate collaboration between clinical and preclinical researchers on specific areas of research. One of those areas involves genetic heart diseases, which are frequently caused by pathogenic variants in genes that encode sarcomere proteins. In 2014, the DOSIS (Determinants of susceptibility in inherited cardiomyopathy: towards novel therapeutic approaches) consortium was initiated, focusing their research on secondary disease hits involved in the onset and progression of cardiomyopathies. Here we highlight several recent observations from our consortium and collaborators which may ultimately be relevant for clinical practice.

Tumour biomarkers: association with heart failure outcomes.

BACKGROUND: There is increasing recognition that heart failure (HF) and cancer are conditions with a number of shared characteristics. OBJECTIVES: To explore the association between tumour biomarkers and HF outcomes. METHODS: In 2,079 patients of BIOSTAT-CHF cohort, we measured six established tumour biomarkers: CA125, CA15-3, CA19-9, CEA, CYFRA 21-1 and AFP. RESULTS: During a median follow-up of 21 months, 555 (27%) patients reached the primary end-point of all-cause mortality. CA125, CYFRA 21-1, CEA and CA19-9 levels were positively correlated with NT-proBNP quartiles (all P < 0.001, P for trend < 0.001) and were, respectively, associated with a hazard ratio of 1.17 (95% CI 1.12-1.23; P < 0.0001), 1.45 (95% CI 1.30-1.61; P < 0.0001), 1.19 (95% CI 1.09-1.30; P = 0.006) and 1.10 (95% CI 1.05-1.16; P < 0.001) for all-cause mortality after correction for BIOSTAT risk model (age, BUN, NT-proBNP, haemoglobin and beta blocker). All tumour biomarkers (except AFP) had significant associations with secondary end-points (composite of all-cause mortality and HF hospitalization, HF hospitalization, cardiovascular (CV) mortality and non-CV mortality). ROC curves showed the AUC of CYFRA 21-1 (0.64) had a noninferior AUC compared with NT-proBNP (0.68) for all-cause mortality (P = 0.08). A combination of CYFRA 21-1 and NT-proBNP (AUC = 0.71) improved the predictive value of the model for all-cause mortality (P = 0.0002 compared with NT-proBNP). CONCLUSIONS: Several established tumour biomarkers showed independent associations with indices of severity of HF and independent prognostic value for HF outcomes. This demonstrates that pathophysiological pathways sensed by these tumour biomarkers are also dysregulated in HF.

Right ventricular pressure overload alters cardiac lipid composition.

INTRODUCTION: Right ventricular (RV) failure due to pressure load is an important determinant of clinical outcome in pulmonary hypertension, congenital heart disease and left ventricular failure. The last decades it has become clear that metabolic dysregulation is associated with the development of RV-failure. However, underlying mechanisms remain to be unraveled. Recently, disruption of intracardiac lipid content has been suggested as potential inducer of RV failure. In the present study, we used a rat model of RV-dysfunction and aimed to obtain insight in temporal changes in RV-function, -remodelling and -metabolism and relate this to RV lipid content. METHODS AND RESULTS: Male Wistar WU rats were subjected to pulmonary artery banding (n = 25) or sham surgery (n = 14) and cellular, hemodynamic and metabolic assessments took place after 2, 5 and 12 weeks. In this model RV dysfunction and remodelling occurred, including early upregulation of oxidative stress markers. After 12 weeks of pressure load, lipidomics revealed significant decreases of myocardial diglycerides and cardiolipins, driven by (poly-)unsaturated forms. The decrease of cardiolipins was driven by its most abundant form, tetralinoleoylcardiolipin. Mitochondrial capacity for fatty acid oxidation preserved, while the capacity for glucose oxidation increased. CONCLUSION: RV dysfunction due to pressure load, is associated with decreased intracardiac unsaturated lipids, especially tetralinoleoylcardiolipin. This was accompanied with preserved mitochondrial capacity regarding fatty acids oxidation, with increased capacity for glucose oxidation, and early activation of oxidative stress. We suggest that early interventions should be directed towards preservation of lipid availability as possible mean in order to prevent RV failure.

The fibrosis-cell death axis in heart failure.

Cardiac stress can induce morphological, structural and functional changes of the heart, referred to as cardiac remodeling. Myocardial infarction or sustained overload as a result of pathological causes such as hypertension or valve insufficiency may result in progressive remodeling and finally lead to heart failure (HF). Whereas pathological and physiological (exercise, pregnancy) overload both stimulate cardiomyocyte growth (hypertrophy), only pathological remodeling is characterized by increased deposition of extracellular matrix proteins, termed fibrosis, and loss of cardiomyocytes by necrosis, apoptosis and/or phagocytosis. HF is strongly associated with age, and cardiomyocyte loss and fibrosis are typical signs of the aging heart. Fibrosis results in stiffening of the heart, conductivity problems and reduced oxygen diffusion, and is associated with diminished ventricular function and arrhythmias. As a consequence, the workload of cardiomyocytes in the fibrotic heart is further augmented, whereas the physiological environment is becoming less favorable. This causes additional cardiomyocyte death and replacement of lost cardiomyocytes by fibrotic material, generating a vicious cycle of further decline of cardiac function. Breaking this fibrosis-cell death axis could halt further pathological and age-related cardiac regression and potentially reverse remodeling. In this review, we will describe the interaction between cardiac fibrosis, cardiomyocyte hypertrophy and cell death, and discuss potential strategies for tackling progressive cardiac remodeling and HF.

Forced activation of Cdk1 via wee1 inhibition impairs homologous recombination.

In response to DNA breaks, the 'DNA damage response' provokes a cell cycle arrest to facilitate DNA repair. Recent findings have indicated that cells can respond to DNA damage throughout the cell cycle, except during mitosis. Specifically, various mitotic kinases, including Cdk1, Aurora A and Plk1, were shown to inactivate key DNA damage checkpoint proteins when cells enter mitosis. Aberrant activation of mitotic kinases during interphase could therefore modulate cellular responses to DNA damage. In this study, our aim was to determine how aberrant activation of Cdk1 affects the cellular responses to DNA damage. We used Wee1 inhibition, using MK-1775, to force Cdk1 activation, which did not cause cytotoxicity in non-transformed cells. Instead, it accelerated mitotic entry and caused radio sensitization in p53-defective cancer cells, but not in p53-proficient cancer cells. Interestingly, we showed that Wee1 inhibition leads to elevation of Cdk1 activity in interphase cells. When we subsequently analyzed DNA damage responses in cells with forced Cdk1 activation, we observed a marked reduction of 53BP1 at sites of DNA damage along with an increase in γ-H2AX staining after irradiation, indicative of defective DNA repair. Indeed, when DNA repair was analyzed using in vivo endonuclease-induced homologous recombination (HR) assays, compromised DNA repair after Wee1 inhibition was confirmed. This defect in HR was accompanied by increased phosphorylation of BRCA2 at the Cdk1 phosphorylation site S3291. Taken together, our results indicate that Wee1 inhibition leads to forced Cdk1 activation in interphase cells, which interferes with normal DNA damage responses.