Glycogen synthase kinase-3 inhibition and insulin enhance proliferation and inhibit maturation of human iPSC-derived cardiomyocytes via TCF and FOXO signaling.

Embryonic signaling pathways exert stage-specific effects during cardiac development, yet the precise signals for proliferation or maturation remain elusive. To uncover the cues for proliferation, we performed a combinatory cell-cycle screen for insulin and glycogen synthase kinase-3 (GSK3) inhibition in spontaneously beating human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). Our analysis for proliferation, and subsequential downstream sarcomere development, gene expression analysis, and molecular interventions identified a temporal interplay between insulin/Akt/FOXO and CHIR99021/Wnt/GSK3/TCF signaling.

Translating metabolic and cardiovascular research into effective treatments: What's next?

The future of healthcare for cardiovascular diseases holds immense promise, not only based in new discoveries in cardiac metabolism but also in translating them to solutions for critical challenges faced by society. Here, ten scientists share their insights, shedding light on the future that lies ahead for this field.

Mechanisms of myocardial reverse remodelling and its clinical significance: A scientific statement of the ESC Working Group on Myocardial Function.

Cardiovascular disease (CVD) is the leading cause of morbimortality in Europe and worldwide. CVD imposes a heterogeneous spectrum of cardiac remodelling, depending on the insult nature, that is, pressure or volume overload, ischaemia, arrhythmias, infection, pathogenic gene variant, or cardiotoxicity. Moreover, the progression of CVD-induced remodelling is influenced by sex, age, genetic background and comorbidities, impacting patients' outcomes and prognosis.

Localized translation and sarcomere maintenance requires ribosomal protein SA in mice.

Cardiomyocyte sarcomeres contain localized ribosomes, but the factors responsible for their localization and the significance of localized translation are unknown. Using proximity labeling, we identified ribosomal protein SA (RPSA) as a Z-line protein. In cultured cardiomyocytes, the loss of RPSA led to impaired local protein translation and reduced sarcomere integrity.

Translating myosin-binding protein C and titin abnormalities to whole-heart function using a novel calcium-contraction coupling model.

Mutations in cardiac myosin-binding protein C (cMyBP-C) or titin may respectively lead to hypertrophic (HCM) or dilated (DCM) cardiomyopathies. The mechanisms leading to these phenotypes remain unclear because of the challenge of translating cellular abnormalities to whole-heart and system function. We developed and validated a novel computer model of calcium-contraction coupling incorporating the role of cMyBP-C and titin based on the key assumptions: 1) tension in the thick filament promotes cross-bridge attachment mechanochemically, 2) with increasing titin tension, more myosin heads are unlocked for attachment, and 3) cMyBP-C suppresses cross-bridge attachment.

A safety screening platform for individualized cardiotoxicity assessment.

Cardiotoxicity remains a major cause of drug withdrawal, partially due to lacking predictability of animal models. Additionally, risk of cardiotoxicity following treatment of cancer patients is treatment limiting. It is unclear which patients will develop heart failure following therapy.

Hypertrophic cardiomyopathy dysfunction mimicked in human engineered heart tissue and improved by sodium-glucose cotransporter 2 inhibitors.

Aims: Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy, often caused by pathogenic sarcomere mutations. Early characteristics of HCM are diastolic dysfunction and hypercontractility. Treatment to prevent mutation-induced cardiac dysfunction is lacking.

The Cardioprotective Effects of Semaglutide Exceed Those of Dietary Weight Loss in Mice With HFpEF.

Obesity-related heart failure with preserved ejection fraction (HFpEF) has become a well-recognized HFpEF subphenotype. Targeting the unfavorable cardiometabolic profile may represent a rational treatment strategy. This study investigated semaglutide, a glucagon-like peptide-1 receptor agonist that induces significant weight loss in patients with obesity and/or type 2 diabetes mellitus and has been associated with improved cardiovascular outcomes.

Geranylgeranylacetone reduces cardiomyocyte stiffness and attenuates diastolic dysfunction in a rat model of cardiometabolic syndrome.

Titin-dependent stiffening of cardiomyocytes is a significant contributor to left ventricular (LV) diastolic dysfunction in heart failure with preserved LV ejection fraction (HFpEF). Small heat shock proteins (HSPs), such as HSPB5 and HSPB1, protect titin and administration of HSPB5 in vitro lowers cardiomyocyte stiffness in pressure-overload hypertrophy. In humans, oral treatment with geranylgeranylacetone (GGA) increases myocardial HSP expression, but the functional implications are unknown.

Acute heart failure: mechanisms and pre-clinical models-a Scientific Statement of the ESC Working Group on Myocardial Function.

While chronic heart failure (CHF) treatment has considerably improved patient prognosis and survival, the therapeutic management of acute heart failure (AHF) has remained virtually unchanged in the last decades. This is partly due to the scarcity of pre-clinical models for the pathophysiological assessment and, consequently, the limited knowledge of molecular mechanisms involved in the different AHF phenotypes. This scientific statement outlines the different trajectories from acute to CHF originating from the interaction between aetiology, genetic and environmental factors, and comorbidities.

DWORF Extends Life Span in a PLN-R14del Cardiomyopathy Mouse Model by Reducing Abnormal Sarcoplasmic Reticulum Clusters.

Background: The p.Arg14del variant of the (phospholamban) gene causes cardiomyopathy, leading to severe heart failure. Calcium handling defects and perinuclear PLN aggregation have both been suggested as pathological drivers of this disease.

Characterization of heterozygous and homozygous mouse models with the most common hypertrophic cardiomyopathy mutation MYBPC3 in the Netherlands.

Hypertrophic cardiomyopathy (HCM) is frequently caused by mutations in the cardiac myosin binding protein-C (cMyBP-C) encoding gene MYBPC3. In the Netherlands, approximately 25% of patients carry the MYBPC3 founder mutation. Most patients are heterozygous (MYBPC3) and have highly variable phenotypic expression, whereas homozygous (MYBPC3) patients have severe HCM at a young age.

The microtubule signature in cardiac disease: etiology, disease stage, and age dependency.

Employing animal models to study heart failure (HF) has become indispensable to discover and test novel therapies, but their translatability remains challenging. Although cytoskeletal alterations are linked to HF, the tubulin signature of common experimental models has been incompletely defined. Here, we assessed the tubulin signature in a large set of human cardiac samples and myocardium of animal models with cardiac remodeling caused by pressure overload, myocardial infarction or a gene defect.

Harnessing developmental cues for cardiomyocyte production.

Developmental research has attempted to untangle the exact signals that control heart growth and size, with knockout studies in mice identifying pivotal roles for Wnt and Hippo signaling during embryonic and fetal heart growth. Despite this improved understanding, no clinically relevant therapies are yet available to compensate for the loss of functional adult myocardium and the absence of mature cardiomyocyte renewal that underlies cardiomyopathies of multiple origins. It remains of great interest to understand which mechanisms are responsible for the decline in proliferation in adult hearts and to elucidate new strategies for the stimulation of cardiac regeneration.

EGFR/IGF1R Signaling Modulates Relaxation in Hypertrophic Cardiomyopathy.

Background: Diastolic dysfunction is central to diseases such as heart failure with preserved ejection fraction and hypertrophic cardiomyopathy (HCM). However, therapies that improve cardiac relaxation are scarce, partly due to a limited understanding of modulators of cardiomyocyte relaxation. We hypothesized that cardiac relaxation is regulated by multiple unidentified proteins and that dysregulation of kinases contributes to impaired relaxation in patients with HCM.

Real-Time Measurements of Calcium and Contractility Parameters in Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) represent a powerful tool for studying mutation-mediated changes in cardiomyocyte function and defining the effects of stressors and drug interventions. In this study, it is demonstrated that this optics-based system is a powerful tool to assess the functional parameters of hiPSC-CMs in 2D. By using this platform, it is possible to perform paired measurements in a well-preserved temperature environment on different plate layouts.

Chronic activation of tubulin tyrosination in HCM mice and human iPSC-engineered heart tissues improves heart function.

Hypertrophic cardiomyopathy (HCM) is the most common cardiac genetic disorder caused by sarcomeric gene variants and associated with left ventricular (LV) hypertrophy and diastolic dysfunction. The role of the microtubule network has recently gained interest with the findings that -α-tubulin detyrosination (dTyr-tub) is markedly elevated in heart failure. Acute reduction of dTyr-tub by inhibition of the detyrosinase (VASH/SVBP complex) or activation of the tyrosinase (tubulin tyrosine ligase, TTL) markedly improved contractility and reduced stiffness in human failing cardiomyocytes, and thus poses a new perspective for HCM treatment.

A systematic literature review of economic evaluations and cost-of-illness studies of inherited cardiomyopathies.

Hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) are commonly inherited heart conditions associated with a high risk of heart failure and sudden cardiac death. To understand the economic and societal disease burden, this study systematically identified and reviewed cost-of-illness (COI) studies and economic evaluations (EEs) of various interventions for HCM and DCM. A literature search was performed in MEDLINE, EMBASE, NHS EED, EconLit and Web of Science to identify COI studies and EEs published between 1 January 2010 and 28 April 2021.

Low expression of the K280N mutation is sufficient to increase basal myofilament activation in human hypertrophy cardiomyopathy.

Background: Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disorder with patients typically showing heterozygous inheritance of a pathogenic variant in a gene encoding a contractile protein. Here, we study the contractile effects of a rare homozygous mutation using explanted tissue and human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to gain insight into how the balance between mutant and WT protein expression affects cardiomyocyte function.

Methods: Force measurements were performed in cardiomyocytes isolated from a HCM patient carrying a homozygous troponin T mutation (cTnT-K280N) and healthy donors.