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AbstractPurpose Cardiovascular diseases (CVDs) are a leading cause of morbidity and mortality worldwide. Ischemic heart diseases, particularly acute myocardial infarction (MI), represent the most common cause of death. MI is influenced by multiple factors, including the release of inflammatory mediators. A significant percentage of individuals with CVD experience psychological effects, such as anxiety and depression, which are linked to an increased risk of coronary heart disease. Certain anti-anxiety medications have demonstrated immunomodulatory and anti-inflammatory effects. Tofisopam, a 2,3-benzodiazepine with anxiolytic properties, has been shown to exert in vitro anti-inflammatory and immunomodulatory effects. The present study investigates the potential of tofisopam as a protective adjuvant against isoprenaline-induced MI in rats and explores the possible underlying mechanisms. Methods: The study included four groups: a control group, a group pretreated with tofisopam, an isoprenaline toxic group, and an isoprenaline toxic group pretreated with tofisopam. Results: The findings demonstrated that isoprenaline significantly increased cardiac enzyme levels, as well as elevated oxidative and inflammatory stress parameters, along with evident apoptosis in cardiac cells. In contrast, the tofisopam-pretreated group showed a significant reversal of the cardiac damage induced by isoprenaline. Conclusions: Tofisopam protects against isoprenaline-induced MI through its antioxidant, anti-inflammatory, and anti-apoptotic properties. [ABSTRACT FROM AUTHOR]

Exercise has long been known to improve cardiovascular health, energy metabolism, and well-being. However, myocardial cell responses to exercise are complex and multifaceted due to their molecular pathways. To understand cardiac physiology and path physiology, one must understand these pathways, including energy autophagy. In recent years, deep learning techniques, IoT devices, and cloud computing infrastructure have enabled real-time, large-scale biological data analysis. The objective of this work is to extract and analyze autophagy properties in exercise-induced cardiac cells in a cloud-IoT context using deep learning, more especially an autoencoder. The Shanghai University of Sport Ethics Committee for Science Research gave its approval for the data collection, which involved 150 male Sprague–Dawley (SD) rats that were eight weeks old and in good health. The Z-score normalization method was used to standardize the data. Fractal optimization methods could be applied to these algorithms. For example, fractal-inspired optimization techniques might be used to analyze deep learning with Autoencoder, the autography energy of exercise myocardial cells within a cloud-IoT. To capture the intricate myocardial energy autophagy during exercise, we introduced the DMO-GCNN-Autoencoder, a Dwarf Mongoose Optimized Graph Convolutional Neural Network. The results showed that the proposed network’s performance matches that of the existing methods. [ABSTRACT FROM AUTHOR]

All new drugs must go through preclinical screening tests to determine their proarrhythmic potential. While these assays effectively filter out dangerous drugs, they are too conservative, often misclassifying safe compounds as proarrhythmic. In this study, we attempt to address this shortcoming with a novel, medium‐throughput drug‐screening approach: we use an automated patch‐clamp system to acquire optimized voltage clamp (VC) and action potential (AP) data from human induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) at several drug concentrations (baseline, 3×, 10× and 20× the effective free plasma concentrations). With our novel method, we show correlations between INa block and upstroke slowing after treatment with flecainide or quinine. Additionally, after quinine treatment, we identify significant reductions in current during voltage steps designed to isolate If and IKs. However, we do not detect any IKr block by either drug, and upon further investigation, do not see any IKr present in the iPSC‐CMs when prepared for automated patch experiments (i.e. in suspension) – this is in contrast to similar experiments we have conducted with these cells using the manual patch setup. In this study, we: (1) present a proof‐of‐concept demonstration of a single‐cell medium‐throughput drug study, and (2) characterize the non‐canonical electrophysiology of iPSC‐CMs when prepared for experiments in a medium‐throughput setting. Key points: Human induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) offer potential as an in vitro model to study the proarrhythmic potential of drugs, but insights from these cells are often limited by the low throughput of manual patch‐clamp.In this study, we use a medium‐throughput automated patch‐clamp system to acquire action potential (AP) and complex voltage clamp (VC) data from single iPSC‐CMs at multiple drug concentrations.A correlation between AP upstroke and INa transients was identified and drug‐induced changes in ionic currents found.We also characterize the substantially altered physiology of iPSC‐CMs when patched in an automated system, suggesting the need to investigate differences between manual and automated patch experiments. [ABSTRACT FROM AUTHOR]

Human induced pluripotent stem cell‐derived cardiomyocytes (iPSC‐CMs) offer potential as an in vitro model for studying drug cardiotoxicity and patient‐specific cardiovascular disease. The inherent electrophysiological heterogeneity of these cells limits the depth of insights that can be drawn from well‐designed experiments. In this review, we provide our perspective on some sources and the consequences of iPSC‐CM heterogeneity. We demonstrate the extent of heterogeneity in the literature and explain how such heterogeneity is exacerbated by patch‐clamp experimental artifacts in the manual and automated set‐up. Finally, we discuss how this heterogeneity, caused by both intrinsic and extrinsic factors, limits our ability to build digital twins of patient‐derived cardiomyocytes. [ABSTRACT FROM AUTHOR]

Acute myocardial infarction (AMI) and related cardiovascular disease complications are the leading causes of mortality worldwide. Brown adipose tissue (BAT) is thermogenic and characterized by the uncoupling protein expression. Recent studies have found that in cardiovascular diseases, activated BAT can effectively improve the prognosis of AMI and concurrent heart failure through intercellular communication. However, a clear and systematic understanding of the myocardial protective mechanism of BAT after AMI is lacking, especially in the endocrine function of BAT. This review describes the effects of BAT on various cells in the heart after AMI. BAT plays a protective role on cardiac cells and fibroblasts during ischemia/reperfusion (I/R), myocardial remodeling, and myocardial fibrosis. This review also discusses the changes caused by BAT activation in different stages of heart failure. Finally, this review summarizes the treatment methods that target BAT to improve AMI. Further in-depth researches are still needed to clarify the underlying mechanism of the connection between BAT and different cells in cardiac tissue in order to identify potential therapeutic targets. [ABSTRACT FROM AUTHOR]

Background: Cell therapy can protect cardiomyocytes from hypoxia, primarily via paracrine secretions, including extracellular vesicles (EVs). Since EVs fulfil specific biological functions based on their cellular origin, we hypothesised that EVs from human cardiac stromal cells (CMSCLCs) obtained from coronary artery bypass surgery may have cardioprotective properties. Objectives: This study characterises CMSCLC EVs (C_EVs), miRNA cargo, cardioprotective efficacy and transcriptomic modulation of hypoxic human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs). C_EVs are compared to bone marrow mesenchymal stromal cell EVs (B_EVs) which are a known therapeutic EV type. Methods: Cells were characterised for surface markers, gene expression and differentiation potential. EVs were compared for yield, phenotype, and ability to protect hiPSC-CMs from hypoxia/reoxygenation injury. EV dose was normalised by both protein concentration and particle count, allowing direct comparison. C_EV and B_EV miRNA cargo was profiled and RNA-seq was performed on EV-treated hypoxic hiPSC-CMs, then data were integrated by multi-omics. Confirmatory experiments were carried out using miRNA mimics. Results: At the same dose, C_EVs were more effective than B_EVs at protecting CM integrity, reducing apoptotic markers, and cell death during hypoxia. While C_EVs and B_EVs shared 70–77% similarity in miRNA content, C_EVs contained unique miRNAs, including miR-202-5p, miR-451a and miR-142-3p. Delivering miRNA mimics confirmed that miR-1260a and miR-202/451a/142 were cardioprotective, and the latter upregulated protective pathways similar to whole C_EVs. Conclusions: This study demonstrates the potential of cardiac tissues, routinely discarded following surgery, as a valuable source of EVs for myocardial infarction therapy. We also identify miR-1260a as protective of CM hypoxia. [ABSTRACT FROM AUTHOR]

Background: Immunoglobulin derived AL amyloidosis and transthyretin derived ATTR amyloidosis are the most common forms of cardiac amyloidosis. Both may present with cardiac arrhythmias, heart failure, and extracardiac symptoms. Disease outcome is often fatal. Recently, it was proposed that amyloid may cause cardiac inflammation. Here we tested the hypothesis that immune cell infiltration in cardiac tissue correlates with clinicopathological patient characteristics. Patients and methods: Myocardial biopsies from 157 patients with cardiac amyloidosis (46.5% AL, 53.3% ATTR) were immunohistochemically assessed for the presence and amount of T lymphocytes (CD3), macrophages (CD68) and neutrophils (MPO). Amyloid load, cardiomyocyte diameter, apoptosis (Caspase 3), necrosis (complement 9), and various clinical parameters were assessed and correlated with immune cell density. Results: Myocardial tissue was infiltrated with T lymphocytes (CD3), macrophages (CD68) and neutrophils (MPO) with variable amounts. Significant correlations were found between the number of macrophages and NYHA class. No correlations were found between the presence and amount of T lymphocytes, neutrophils and clinicopathological patient characteristics. Conclusion: The significant correlation between cardiac macrophage density and heart failure points towards a significant role of macrophages in disease pathology. [ABSTRACT FROM AUTHOR]

Cardiac lymphoma is uncommon in cats and is rarely considered as a differential diagnosis for congestive heart failure. A 10-year-old neutered male domestic short-haired cat with clinical histories of feline immunodeficiency virus, diabetes mellitus, and congestive heart failure was humanely euthanized. Post-mortem evaluation demonstrated a massively infiltrative round cell neoplasm of the heart, resulting in CHF. Immunohistochemistry of neoplastic tissue was consistent with diffuse large B-cell lymphoma. This case demonstrates a peculiar presentation of cardiac diffuse large B-cell lymphoma, with chronic feline lentiviral infection possibly contributing to disease initiation and progression. [ABSTRACT FROM AUTHOR]

We examine stochastic phase models for the community effect of cardiac muscle cells. Our model extends the stochastic integrate-and-fire model by incorporating irreversibility after beating, induced beating, and refractoriness. We focus on investigating the expectation and variance in the synchronized beating interval. Specifically, for a single isolated cell, we obtain the closed-form expectation and variance in the beating interval, discovering that the coefficient of variation has an upper limit of 2 / 3 . For two coupled cells, we derive the partial differential equations for the expected synchronized beating intervals and the distribution density of phases. Furthermore, we consider the conventional Kuramoto model for both two- and N-cell models. We establish a new analysis using stochastic calculus to obtain the coefficient of variation in the synchronized beating interval, thereby improving upon existing literature. [ABSTRACT FROM AUTHOR]

Cardiovascular disease is a leading cause of morbidity and mortality, and exercise-training (TRN) is known to reduce risk factors and protect the heart from ischemia and reperfusion injury. Though the cardioprotective effects of exercise are well-documented, underlying mechanisms are not well understood. This review highlights recent findings and focuses on cardiac factors with emphasis on K+ channel control of the action potential duration (APD), β-adrenergic and adenosine regulation of cardiomyocyte function, and mitochondrial Ca2+ regulation. TRN-induced prolongation and shortening of the APD at low and high activation rates, respectively, is discussed in the context of a reduced response of the sarcolemma delayed rectifier potassium channel (IK) and increased content and activation of the sarcolemma KATP channel. A proposed mechanism underlying the latter is presented, including the phosphatidylinositol-3kinase/protein kinase B pathway. TRN induced increases in cardiomyocyte contractility and the response to adrenergic agonists are discussed. The TRN-induced protection from reperfusion injury is highlighted by the increased content and activation of the sarcolemma KATP channel and the increased phosphorylated glycogen synthase kinase-3β, which aid in preventing mitochondrial Ca2+ overload and mitochondria-triggered apoptosis. Finally, a brief section is presented on the increased incidences of atrial fibrillation associated with age and in life-long exercisers. [ABSTRACT FROM AUTHOR]

Mesothelial and epicardial cells give rise to various types of mesenchymal cells via epithelial (mesothelial)‐to‐mesenchymal transition during development. However, the genes controlling the differentiation and diversification of mesothelial/epicardial cells remain unclear. Here, we examined Wnt2b expression in the embryonic mesothelium and epicardium and performed lineage tracing of Wnt2b‐expressing cells by using novel Wnt2b‐2A‐CreERT2 knock‐in and LacZ‐reporter mice. Wnt2b was expressed in mesothelial cells covering visceral organs, but the expression was restricted in their subpopulations. Wnt2b‐expressing cells labeled at embryonic day (E) 10.5 were distributed to the mesothelium and mesenchyme in the lungs, abdominal wall, stomach, and spleen in Wnt2b2A‐CreERT2/+;R26RLacZ/+ mice at E13.0. Wnt2b was initially expressed in the proepicardial organ (PEO) at E9.5 and then in the epicardium after E10.0. Wnt2b‐expressing PEO cells labeled at E9.5 differentiated into a small fraction of cardiac fibroblasts and preferentially localized at the left side of the postnatal heart. LacZ+ epicardium‐derived cells labeled at E10.5 differentiated into a small fraction of fibroblasts and smooth muscle cells in the postnatal heart. Taken together, our results reveal novel subpopulations of PEO and mesothelial/epicardial cells that are distinguishable by Wnt2b expression and elucidate the unique contribution of Wnt2b‐expressing PEO and epicardial cells to the postnatal heart. [ABSTRACT FROM AUTHOR]

The heart is an organ with a low ability to renew and repair itself. MSCs have cell surface markers such as CD45−, CD34−, CD31−, CD4+, CD11a+, CD11b+, CD15+, CD18+, CD25+, CD49d+, CD50+, CD105+, CD73+, CD90+, CD9+, CD10+, CD106+, CD109+, CD127+, CD120a+, CD120b+, CD124+, CD126+, CD140a+, CD140b+, adherent properties and the ability to differentiate into cells such as adipocytes, osteoblasts and chondrocytes. Autogenic, allogeneic, normal, pretreated and genetically modified MSCs and secretomes are used in preclinical and clinical studies. MSCs and their secretomes (the total released molecules) generally have cardioprotective effects. Studies on cardiovascular diseases using MSCs and their secretomes include myocardial infraction/ischemia, fibrosis, hypertrophy, dilated cardiomyopathy and atherosclerosis. Stem cells or their secretomes used for this purpose are administered to the heart via intracoronary (Antegrade intracoronary and retrograde coronary venous injection), intramyocardial (Transendocardial and epicardial injection) and intravenous routes. The protective effects of MSCs and their secretomes on the heart are generally attributed to their differentiation into cardiomyocytes and endothelial cells, their immunomodulatory properties, paracrine effects, increasing blood vessel density, cardiac remodeling, and ejection fraction and decreasing apoptosis, the size of the wound, end-diastolic volume, end-systolic volume, ventricular myo-mass, fibrosis, matrix metalloproteins, and oxidative stress. The present review aims to assist researchers and physicians in selecting the appropriate cell type, secretomes, and technique to increase the chance of success in designing therapeutic strategies against cardiovascular diseases. [ABSTRACT FROM AUTHOR]

Nowadays, cardiovascular diseases are the most common cause of death worldwide. Besides, atherosclerosis is a cardiovascular disease that occurs with persistent narrowing of arteries, especially medium and large-sized arteries. Atherosclerosis begins with a local elevation in the permeability of the arterial wall as a result of endothelial inflammation. Subsequently, excess LDL permeates into the arterial wall. Then, through several chemical responses and reactions, foam cells are produced. These foam cells serve as a crucial indicator for assessing the development of atherosclerosis within the arteries. In this study, the effect of endothelial layer modeling, heart rate (HR) and hypertension on the foam cell accumulation is numerically investigated in a patient-specific geometry of the human thoracic aorta. Navier–Stokes, Darcy, and mass transfer equations are used to obtain the velocity and concentration field within the domain. Regarding the dependence of endothelial cell properties on time-averaged wall shear stress, it is observed that foam cells are mainly concentrated in the outer curvature of the aortic arch, downstream of the left subclavian artery. However, considering oscillatory-shear-rate as the determinant of endothelial cell properties leads to the accumulation of foam cells in the inner curvature of the descending aorta. Regarding the HR, with the increase of HR, the volume average concentration of the foam cell decreases. However, there is no substantial difference between the cases of different HRs. Moreover, foam cell concentration significantly increases in the hypertension case. This result implies that a slight increase in the blood pressure may induce irreparable problems in the circulatory system. [ABSTRACT FROM AUTHOR]

Splenic leukocytes, particularly macrophage-expressed lipoxygenases, facilitate the biosynthesis of resolution mediators essential for cardiac repair. Next, we asked whether deletion of 12/15 lipoxygenase (12/15LOX) in macrophages impedes the resolution of inflammation following myocardial infarction (MI). Using 12/15flox/flox and LysMcre scheme, we generated macrophage-specific 12/15LOX (Mɸ-12/15LOX−/−) mice. Young C57BL/6J wild-type and Mɸ-12/15LOX−/− male mice were subjected to permanent coronary ligation microsurgery. Mice were monitored at day 1 (d1) to d5 (as acute heart failure [AHF]) and to d56 (chronic HF) post-MI, maintaining no MI as d0 naïve control animals. Post ligation, Mɸ-12/15LOX−/− mice showed increased survival (88% vs 56%) and limited heart dysfunction compared with wild-type. In AHF, Mɸ-12/15LOX−/− mice have increased biosynthesis of epoxyeicosatrienoic acid by 30%, with the decrease in D-series resolvins, protectin, and maresin by 70% in the infarcted heart. Overall, myeloid cell profiling from the heart and spleen indicated that Mɸ-12/15LOX−/− mice showed higher immune cells with reparative Ly6Clow macrophages during AHF. In addition, the detailed immune profiling revealed reparative macrophage phenotype (Ly6Clow) in Mɸ-12/15LOX−/− mice in a splenocardiac manner post-MI. Mɸ-12/15LOX−/− mice showed an increase in myeloid population that coordinated increase of T regulatory cells (CD4+/Foxp3+) in the spleen and injured heart at chronic HF compared with wild-type. Thus, macrophage-specific deletion of 12/15LOX directs reparative macrophage phenotype to facilitate cardiac repair. The presented study outlines the complex role of 12/15LOX in macrophage plasticity and T regulatory cell signaling that indicates that resolution mediators are viable targets to facilitate cardiac repair in HF post-MI. [ABSTRACT FROM AUTHOR]

Acute myocardial infarction, often associated with ischemia/reperfusion injury (I/R), is a leading cause of death worldwide. Although the endogenous tryptophan metabolite kynurenic acid (KYNA) has been shown to exert protection against I/R injury, its mechanism of action at the cellular and molecular level is not well understood yet. Therefore, we examined the potential involvement of antiapoptotic mechanisms, as well as N-methyl-D-aspartate (NMDA) receptor modulation in the protective effect of KYNA in cardiac cells exposed to simulated I/R (SI/R). KYNA was shown to attenuate cell death induced by SI/R dose-dependently in H9c2 cells or primary rat cardiomyocytes. Analysis of morphological and molecular markers of apoptosis (i.e., membrane blebbing, apoptotic nuclear morphology, DNA double-strand breaks, activation of caspases) revealed considerably increased apoptotic activity in cardiac cells undergoing SI/R. The investigated apoptotic markers were substantially improved by treatment with the cytoprotective dose of KYNA. Although cardiac cells were shown to express NMDA receptors, another NMDA antagonist structurally different from KYNA was unable to protect against SI/R-induced cell death. Our findings provide evidence that the protective effect of KYNA against SI/R-induced cardiac cell injury involves antiapoptotic mechanisms, that seem to evoke independently of NMDA receptor signaling. [ABSTRACT FROM AUTHOR]

BACKROUND Complement activation may facilitate hypertension through its effects on immune responses. The anaphylatoxin C5a, a major inflammatory effector, binds to the C5a receptors 1 and 2 (C5aR1, C5aR2). We have recently shown that C5aR1−/− mice have reduced hypertensive renal injury. The role of C5aR2 in hypertension is unknown. METHODS For examination of C5aR2 expression on infiltrating and resident renal cells a tandem dye Tomato-C5aR2 knock-in reporter mouse was used. Human C5aR2 expression was analyzed in a single-cell RNAseq data set from the kidneys of hypertensive patients. Finally, we examined the effect of angiotensin II-induced hypertension in C5aR2-deficient mice. RESULTS Flow cytometric analysis of leukocytes isolated from kidneys of the reporter mice showed that dendritic cells are the major C5aR2-expressing population (34%) followed by monocyte/macrophages (30%) and neutrophils (14%). Using confocal microscopy C5aR2 was not detected in resident renal or cardiac cells. In the human kidney, C5aR2 was also mainly found in monocytes, macrophages, and dendritic cells with a significantly higher expression in hypertension (P  < 0.05). Unilateral nephrectomy was performed followed by infusion of Ang II (0.75 ng/g/min) and a high salt diet in wildtype (n  = 18) and C5aR2-deficient mice (n  = 14). Blood pressure, renal injury (albuminuria, glomerular filtration rate, glomerular and tubulointerstitial injury, inflammation), and cardiac injury (cardiac fibrosis, heart weight, gene expression) did not differ between hypertensive wildtype and C5aR2−/− mice. CONCLUSIONS In summary, C5aR2 is mainly expressed in myeloid cells in the kidney in mice and humans but its deficiency has no effect on Ang II-induced hypertensive injury. [ABSTRACT FROM AUTHOR]

Background: Gasdermin D (GSDMD) mediated pyroptosis plays a significant role in the pathophysiology of myocardial ischemia/reperfusion (I/R) injury. However, the precise mechanisms regulating pyroptosis remain unclear. In the study, we aimed to investigate the underlying mechanism of pyroptosis in myocardial I/R injury. Methods: In the present study, we analyzed the effects of USP5 on the RIPK1 kinase activity mediated pyroptosis in vitro after H/R (hypoxia/reoxygenation) and in vivo in a MI/R mouse model. TTC and Evan's blue dye, Thioflavin S and immunohistochemistry staining were performed in wild-type, RIPK1flox/flox Cdh5-Cre and USP5 deficiency mice. CMEC cells were transfected with si-USP5. HEK293T cells were transfected with USP5 and RIPK1 overexpression plasmid or its mutants. The levels of USP5, RIPK1, Caspase-8, FADD and GSDMD were determined by Western blot. Protein interactions were evaluated by immunoprecipitation. The protein colocalization in cells was monitored using a confocal microscope. Results: In this study, our data demonstrate that RIPK1 is essential for limiting cardiac endothelial cell (CMEC) pyroptosis mediated by caspase-8 in response to myocardial I/R. Additionally, we investigate the role of ubiquitin-specific protease 5 (USP5) as a deubiquitinase for RIPK1. Mechanistically, USP5 interacts with RIPK1, leading to its deubiquitination and stabilization. Conclusions: These findings offer new insights into the role of USP5 in regulating RIPK1-induced pyroptosis. [ABSTRACT FROM AUTHOR]

Environmental stressors such as micro‐ and nanosized plastic particles (MNPs) or crude oil have a detrimental effect on aquatic animals; however, the impact upon the cardiovascular system of fish remains relatively under‐researched. This study presents a novel approach for investigating the effect of crude oil and MNPs on the cardiac system of fish. We used salmonid larvae and cardiac cell cultures derived from hearts of salmonid fish and exposed them to environmental stressors. Following exposure to plastic particles or crude oil, the larvae exhibited some variation in contraction rate. In contrast, significant alterations in the contraction rate were observed in all cardiac cell cultures. The greatest differences between the control and treatment groups were observed in cardiac cell cultures derived from older brown trout. Following 7 days of exposure to MNPs or crude oil in Atlantic salmon larval hearts or cardiac cell cultures, there were only minor responses noted in mRNA expression of the selected marker genes. These findings show the use of a novel in vitro technique contributing to the existing body of knowledge on the impact of MNPs and crude oil on the cardiovascular system of salmonids and the associated risk. [ABSTRACT FROM AUTHOR]

Heart failure with preserved ejection fraction (HFpEF) is a condition that develops in the course of many diseases and conditions, and its pathophysiology is still not well understood, but the involvement of programmed types of cell death in the development of this type of heart failure is becoming increasingly certain. In addition, drugs already widely used in clinical practice, with a good safety profile and efficacy demonstrated in large-group clinical trials, seem to be exerting their beneficial effects on cardiovascular health. Perhaps new drugs that reduce the susceptibility of cells to programmed types of cell death are under investigation and may improve the prognosis of patients with HFpEF. In this article, we summarize the current knowledge about the pathogenesis of HFpEF and the role of programmed types of cell death in its development. Additionally, we have described the future directions of research that may lead to the improvement of a patient's prognosis and potential treatment. [ABSTRACT FROM AUTHOR]

Mechanical load is a potent regulator of cardiac structure and function. Although high workload during heart failure is associated with disruption of cardiomyocyte t‐tubules and Ca2+ homeostasis, it remains unclear whether changes in preload and afterload may promote adaptive t‐tubule remodelling. We examined this issue by first investigating isolated effects of stepwise increases in load in cultured rat papillary muscles. Both preload and afterload increases produced a biphasic response, with the highest t‐tubule densities observed at moderate loads, whereas excessively low and high loads resulted in low t‐tubule levels. To determine the baseline position of the heart on this bell‐shaped curve, mice were subjected to mildly elevated preload or afterload (1 week of aortic shunt or banding). Both interventions resulted in compensated cardiac function linked to increased t‐tubule density, consistent with ascension up the rising limb of the curve. Similar t‐tubule proliferation was observed in human patients with moderately increased preload or afterload (mitral valve regurgitation, aortic stenosis). T‐tubule growth was associated with larger Ca2+ transients, linked to upregulation of L‐type Ca2+ channels, Na+–Ca2+ exchanger, mechanosensors and regulators of t‐tubule structure. By contrast, marked elevation of cardiac load in rodents and patients advanced the heart down the declining limb of the t‐tubule–load relationship. This bell‐shaped relationship was lost in the absence of electrical stimulation, indicating a key role of systolic stress in controlling t‐tubule plasticity. In conclusion, modest augmentation of workload promotes compensatory increases in t‐tubule density and Ca2+ cycling, whereas this adaptation is reversed in overloaded hearts during heart failure progression. Key points: Excised papillary muscle experiments demonstrated a bell‐shaped relationship between cardiomyocyte t‐tubule density and workload (preload or afterload), which was only present when muscles were electrically stimulated.The in vivo heart at baseline is positioned on the rising phase of this curve because moderate increases in preload (mice with brief aortic shunt surgery, patients with mitral valve regurgitation) resulted in t‐tubule growth. Moderate increases in afterload (mice and patients with mild aortic banding/stenosis) similarly increased t‐tubule density.T‐tubule proliferation was associated with larger Ca2+ transients, with upregulation of the L‐type Ca2+ channel, Na+–Ca2+ exchanger, mechanosensors and regulators of t‐tubule structure.By contrast, marked elevation of cardiac load in rodents and patients placed the heart on the declining phase of the t‐tubule–load relationship, promoting heart failure progression.The dependence of t‐tubule structure on preload and afterload thus enables both compensatory and maladaptive remodelling, in rodents and humans. [ABSTRACT FROM AUTHOR]

The transient receptor potential melastatin 4 (TRPM4) channel contributes extensively to cardiac electrical activity, especially cardiomyocyte action potential formation. Mechanical stretch can induce changes in heart rate and rhythm, and the mechanosensitive channel Piezo1 is expressed in many cell types within the myocardium. Our previous study showed that TRPM4 and Piezo1 are closely co‐localized in the t‐tubules of ventricular cardiomyocytes and contribute to the Ca2+‐dependent signalling cascade that underlies hypertrophy in response to mechanical pressure overload. However, there was no direct evidence showing that Piezo1 activation was related to TRPM4 activation in situ. In the present study, we employed the HL‐1 mouse atrial myocyte‐like cell line as an in vitro model to investigate whether Piezo1–TRPM4 coupling can affect action potential properties. We used the small molecule Piezo1 agonist, Yoda1, as a surrogate for mechanical stretch to activate Piezo1 and detected the action potential changes in HL‐1 cells using FluoVolt, a fluorescent voltage sensitive dye. Our results demonstrate that Yoda1‐induced activation of Piezo1 changes the action potential frequency in HL‐1 cells. This change in action potential frequency is reduced by Piezo1 knockdown using small intefering RNA. Importantly knockdown or pharmacological inhibition of TRPM4 significantly affected the degree to which Yoda1‐evoked Piezo1 activation influenced action potential frequency. Thus, the present study provides in vitro evidence of a functional coupling between Piezo1 and TRPM4 in a cardiomyocyte‐like cell line. The coupling of a mechanosensitive Ca2+ permeable channel and a Ca2+‐activated TRP channel probably represents a ubiquitous model for the role of TRP channels in mechanosensory transduction. Key points: The transient receptor potential melastatin 4 (TRPM4) and Piezo1 channels have been confirmed to contribute to the Ca2+‐dependent signalling cascade that underlies cardiac hypertrophy in response to mechanical pressure overload. However, there was no direct evidence showing that Piezo1 activation was related to TRPM4 activation in situ.We employed the HL‐1 mouse atrial myocyte‐like cell line as an in vitro model to investigate the effect of Piezo1–TRPM4 coupling on cardiac electrical properties.The results show that both pharmacological and genetic inhibition of TRPM4 significantly affected the degree to which Piezo1 activation influenced action potential frequency in HL‐1 cells.Our findings provide in vitro evidence of a functional coupling between Piezo1 and TRPM4 in a cardiomyocyte‐like cell line.The coupling of a mechanosensitive Ca2+ permeable channel and a Ca2+‐activated TRP channel probably represents a ubiquitous model for the role of TRP channels in mechanosensory transduction in various (patho)physiological processes. [ABSTRACT FROM AUTHOR]

Cardiac electrophysiology and mechanics are strongly interconnected. Their interaction is, among others, mediated by mechano‐electric feedback through stretch‐activated ion channels (SACs). The electrophysiological changes induced by SACs may contribute to arrhythmogenesis, but the precise SAC‐induced electrophysiological changes remain incompletely understood. Here, we provide a systematic characterization of stretch effects through three distinguished SACs on cardiac electrophysiology using computational modelling. We implemented potassium‐selective, calcium‐selective and non‐selective SACs in the Tomek–Rodriguez–O'Hara–Rudy model of human ventricular electrophysiology. The model was calibrated to experimental data from isolated cardiomyocytes undergoing stretch, considering inter‐species differences, and disease‐related remodelling of SACs. SAC‐mediated effects on the action potential (AP) were analysed by varying stretch amplitude, application timing and/or duration. Afterdepolarizations of different amplitudes were observed with transient 10‐ms stretch stimuli of 15–18% applied during phase 4, while stretch ≥18% during phase 4 elicited triggered APs. Longer stimuli shifted the threshold of AP trigger during phase 4 to lower amplitudes, while shorter stimuli increased it. Continuous stretch provoked electrophysiological remodelling. Furthermore, stretch shortened duration or changed morphology of a subsequent electrically evoked AP, and, if applied during a vulnerable time window with sufficient amplitude, prevented its occurrence because of stretch‐induced modulation of sodium and L‐type calcium channel gating. These effects were more pronounced with disease‐related SAC remodelling due to increased stretch sensitivity of diseased hearts. We showed that SACs may induce afterdepolarizations and triggered activities, and prevent subsequent AP generation or change its morphology. These effects depend on cardiomyocyte stretch characteristics and disease‐related SACs remodelling and may contribute to cardiac arrhythmogenesis. Key points: The interplay between cardiac electrophysiology and mechanics is mediated by mechano‐electric feedback through stretch‐activated ion channels (SACs). These channels may be pro‐arrhythmic, but their precise effect on electrophysiology remains unclear.Here we present a systematic in silico characterization of stretch effects through three SACs by implementing inter‐species differences as well as disease‐related remodelling of SACs in a novel computational model of human ventricular cardiomyocyte electrophysiology.Our simulations showed that, at the cellular level, SACs may provoke electrophysiological remodelling, afterdepolarizations, triggered activities, change the morphology or shorten subsequent electrically evoked action potentials. The model further suggests that a vulnerable window exists in which stretch prevents the following electrically triggered beat occurrence.The pro‐arrhythmic effects of stretch strongly depend on disease‐related SAC remodelling as well as on stretch characteristics, such as amplitude, time of application and duration. Our study helps in understanding the role of stretch in cardiac arrhythmogenesis and revealing the underlying cellular mechanisms. [ABSTRACT FROM AUTHOR]

Mechano‐electric regulations (MER) play an important role in the maintenance of cardiac performance. Mechano‐calcium and mechano‐electric feedback (MCF and MEF) pathways adjust the cardiomyocyte contractile force according to mechanical perturbations and affects electro‐mechanical coupling. MER integrates all these regulations in one unit resulting in a complex phenomenon. Computational modelling is a useful tool to accelerate the mechanistic understanding of complex experimental phenomena. We have developed a novel model that integrates the MER loop for human atrial cardiomyocytes with proper consideration of feedforward and feedback pathways. The model couples a modified version of the action potential (AP) Koivumäki model with the contraction model by Quarteroni group. The model simulates iso‐sarcometric and isometric twitches and the feedback effects on AP and Ca2+‐handling. The model showed a biphasic response of Ca2+ transient (CaT) peak to increasing pacing rates and highlights the possible mechanisms involved. The model has shown a shift of the threshold for AP and CaT alternans from 4.6 to 4 Hz under post‐operative atrial fibrillation, induced by depressed SERCA activity. The alternans incidence was dependent on a chain of mechanisms including RyRs availability time, MCF coupling, CaMKII phosphorylation, and the stretch levels. As a result, the model predicted a 10% slowdown of conduction velocity for a 20% stretch, suggesting a role of stretch in creation of substrate formation for atrial fibrillation. Overall, we conclude that the developed model provides a physiological CaT followed by a physiological twitch. This model can open pathways for the future studies of human atrial electromechanics. Key points: With the availability of human atrial cellular data, interest in atrial‐specific model integration has been enhanced.We have developed a detailed mathematical model of human atrial cardiomyocytes including the mechano‐electric regulatory loop. The model has gone through calibration and evaluation phases against a wide collection of available human in‐vitro data.The usefulness of the model for analysing clinical problems has been preliminaryly tested by simulating the increased incidence of Ca2+ transient and action potential alternans at high rates in post‐operative atrial fibrillation condition.The model determines the possible role of mechano‐electric feedback in alternans incidence, which can increase vulnerability to atrial arrhythmias by varying stretch levels.We found that our physiologically accurate description of Ca2+ handling can reproduce many experimental phenomena and can help to gain insights into the underlying pathophysiological mechanisms. [ABSTRACT FROM AUTHOR]

Contraction of cardiomyocytes is initiated at subcellular elements called dyads, where L‐type Ca2+ channels in t‐tubules are located within close proximity to ryanodine receptors in the sarcoplasmic reticulum. While evidence from small rodents indicates that dyads are assembled gradually in the developing heart, it is unclear how this process occurs in large mammals. We presently examined dyadic formation in fetal and newborn sheep (Ovis aries), and the regulation of this process by fetal cardiac workload. By employing advanced imaging methods, we demonstrated that t‐tubule growth and dyadic assembly proceed gradually during fetal sheep development, from 93 days of gestational age until birth (147 days). This process parallels progressive increases in fetal systolic blood pressure, and includes step‐wise colocalization of L‐type Ca2+ channels and the Na+/Ca2+ exchanger with ryanodine receptors. These proteins are upregulated together with the dyadic anchor junctophilin‐2 during development, alongside changes in the expression of amphiphysin‐2 (BIN1) and its partner proteins myotubularin and dynamin‐2. Increasing fetal systolic load by infusing plasma or occluding the post‐ductal aorta accelerated t‐tubule growth. Conversely, reducing fetal systolic load with infusion of enalaprilat, an angiotensin converting enzyme inhibitor, blunted t‐tubule formation. Interestingly, altered t‐tubule densities did not relate to changes in dyadic junctions, or marked changes in the expression of dyadic regulatory proteins, indicating that distinct signals are responsible for maturation of the sarcoplasmic reticulum. In conclusion, augmenting blood pressure and workload during normal fetal development critically promotes t‐tubule growth, while additional signals contribute to dyadic assembly. Key points: T‐tubule growth and dyadic assembly proceed gradually in cardiomyocytes during fetal sheep development, from 93 days of gestational age until the post‐natal stage.Increasing fetal systolic load by infusing plasma or occluding the post‐ductal aorta accelerated t‐tubule growth and hypertrophy.In contrast, reducing fetal systolic load by enalaprilat infusion slowed t‐tubule development and decreased cardiomyocyte size.Load‐dependent modulation of t‐tubule maturation was linked to altered expression patterns of the t‐tubule regulatory proteins junctophilin‐2 and amphiphysin‐2 (BIN1) and its protein partners.Altered t‐tubule densities did not influence dyadic formation, indicating that distinct signals are responsible for maturation of the sarcoplasmic reticulum. [ABSTRACT FROM AUTHOR]

Background and Purpose: The ryanodine receptor 2 (RyR2) is present in both the heart and kidneys, and plays a crucial role in maintaining intracellular Ca2+ homeostasis in cells in these organs. This study aimed to investigate the impact of M201‐A on RyR2, as well as studying its effects on cardiac and renal functions in preclinical and clinical studies. Experimental Approach: Following the administration of M201‐A (1,4‐benzothiazepine‐1‐oxide derivative), we monitored diastolic Ca2+ leak via RyR2 and intracellular Ca2+ concentration in isolated rat cardiomyocytes and in cardiac and renal function in animals. In a clinical study, M201‐A was administered intravenously at doses of 0.2 and 0.4 mg·kg−1 once daily for 20 min for four consecutive days in healthy males, with the assessment of haemodynamic responses. Key Results: In rat heart cells, M201‐A effectively inhibited spontaneous diastolic Ca2+ leakage through RyR2 and exhibited positive lusi‐inotropic effects on the rat heart. Additionally, it enhanced natriuresis and improved renal function in dogs. In human clinical studies, when administered intravenously, M201‐A demonstrated an increase in natriuresis, glomerular filtration rate and creatinine clearance, while maintaining acceptable levels of drug safety and tolerability. Conclusions and Implications: The novel drug M201‐A inhibited diastolic Ca2+ leak via RyR2, improved cardiac lusi‐inotropic effects in rats, and enhanced natriuresis and renal function in humans. These findings suggest that this drug may offer a potential new treatment option for chronic kidney disease and heart failure. [ABSTRACT FROM AUTHOR]

The role of fructose consumption in the development of obesity, MetS, and CVD epidemic has been widely documented. Notably, among other effects, fructose consumption has been demonstrated to induce cardiac hypertrophy. Moreover, fructose intake during pregnancy can cause hypertrophy of the maternal heart. Our previous research has demonstrated that maternal fructose intake has detrimental effects on fetuses, which persist into adulthood and are exacerbated upon re-exposure to fructose. Additionally, we found that maternal fructose consumption produces changes in female progeny that alter their own pregnancy. Despite these findings, fructose intake during pregnancy is not currently discouraged. Given that cardiac hypertrophy is a prognostic marker for heart disease and heart failure, this study aimed to determine whether metabolic changes occurring during pregnancy in the female progeny of fructose-fed mothers could provoke a hypertrophic heart. To test this hypothesis, pregnant rats from fructose-fed mothers, with (FF) and without (FC) fructose supplementation, were studied and compared to pregnant control rats (CC). Maternal hearts were analyzed. Although both FF and FC mothers exhibited heart hypertrophy compared to CC rats, cardiac DNA content was more diminished in the hearts of FF dams than in those of FC rats, suggesting a lower number of heart cells. Accordingly, changes associated with cardiac hypertrophy, such as HIF1α activation and hyperosmolality, were observed in both the FC and FF dams. However, FF dams also exhibited higher oxidative stress, lower autophagy, and decreased glutamine protection against hypertrophy than CC dams. In conclusion, maternal fructose intake induces changes in female progeny that alter their own pregnancy, leading to cardiac hypertrophy, which is further exacerbated by subsequent fructose intake. [ABSTRACT FROM AUTHOR]

Background: Cardiac lipid metabolism reprogramming is recognized as a critical pathological factor in the progression of chronic heart failure (CHF). The therapeutic potential of digilanid C and electroacupuncture stimulation (ES) in enhancing lipid metabolism and cardiac function has been established. However, the optimal synergistic regulatory strategies of these interventions on cardiac lipid metabolism have yet to be elucidated. Methods: This study aimed to comprehensively evaluate the impact of a digilanid C-ES combination on cardiac steatosis remodeling in CHF. Assessments were conducted across various dimensions, including myocardial oxygen consumption, mitochondrial function, and lipid metabolism. Additionally, we sought to uncover the underlying neuromolecular mechanisms. Results: Our findings, at both molecular and morphological levels, indicated that the synergistic application of digilanid C and ES significantly inhibited myocardial fibrosis and steatosis. This combination therapy facilitated the repair of cardiac neuro-vascular uncoupling and induced a reprogramming of lipid metabolism. Notably, the digilanid C-ES combination ameliorated cardiomyocyte apoptosis and enhanced mitochondrial biogenesis in CHF, leading to a restructured energy supply pattern. Cardiac immunofluorescence analyses revealed the aggregation of cardiac glial cells (CGCs) at sites of abnormal neurovascular coupling, a response to cardiac lipid degeneration. This was accompanied by a marked reduction in the abnormally elevated expression of interleukin 6 (IL-6) and glutamatergic signaling, which correlated with the severity of cardiac steatosis and the aberrant activation of CGCs. The combined therapy was found to activate the Janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3) pathway, effectively attenuated lipid accumulation and overrecruitment of CGCs and deprivation of glutamatergic nerves. Conclusion: These findings underscore the potential of digilanid C and ES combination therapy as a novel approach to modulate the complex interplay between neurovascular dynamics and metabolic dysregulation in CHF. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular progenitor cells (CPCs) derived from human embryonic stem cells (hESCs) are considered valuable cell sources for investigating cardiovascular physiology in vitro. Meeting the diverse needs of this application requires the large-scale production of CPCs in an in vitro environment. This study aimed to use an effective culture system utilizing signaling factors for the large-scale expansion of hESC-derived CPCs with the potential to differentiate into functional cardiac lineage cells. Methods and results: Initially, CPCs were generated from hESCs using a 4-day differentiation protocol with a combination of four small molecules (CHIR99021, IWP2, SB-431542, and purmorphamine). These CPCs were then expanded and maintained in a medium containing three factors (bFGF, CHIR, and A83-01), resulting in a > 6,000-fold increase after 8 passages. These CPCs were successfully cryopreserved for an extended period in late passages. The expanded CPCs maintained their gene and protein expression signatures as well as their differentiation capacity through eight passages. Additionally, these CPCs could differentiate into four types of cardiac lineage cells: cardiomyocytes, endothelial cells, smooth muscle cells, and fibroblasts, demonstrating appropriate functionality. Furthermore, the coculture of these CPC-derived cardiovascular lineage cells in rat tail collagen resulted in cardiac microtissue formation, highlighting the potential of this 3D platform for studying cardiovascular physiology in vitro. Conclusion: In conclusion, expandable hESC-derived CPCs demonstrated the ability to self-renewal and differentiation into functional cardiovascular lineage cells consistently across passages, which may apply as potential cell sources for in vitro cardiovascular studies. [ABSTRACT FROM AUTHOR]

Throughout our lifetime the heart executes cycles of contraction and relaxation to meet the body's ever‐changing metabolic needs. This vital function is continuously regulated by the autonomic nervous system. Cardiovascular dysfunction and autonomic dysregulation are also closely associated; however, the degrees of cause and effect are not always readily discernible. Thus, to better understand cardiovascular disorders, it is crucial to develop model systems that can be used to study the neurocardiac interaction in healthy and diseased states. Human pluripotent stem cell (hiPSC) technology offers a unique human‐based modelling system that allows for studies of disease effects on the cells of the heart and autonomic neurons as well as of their interaction. In this review, we summarize current understanding of the embryonic development of the autonomic, cardiac and neurocardiac systems, their regulation, as well as recent progress of in vitro modelling systems based on hiPSCs. We further discuss the advantages and limitations of hiPSC‐based models in neurocardiac research. [ABSTRACT FROM AUTHOR]

The heart is a multicellular system, and the intercellular crosstalk mechanism is very important for the growth and development of the heart and even the organs, tissues, and cells at a distance. As a kind of extracellular vesicle, exosomes are released by different types of cells and can carry specific genetic material, endosomal proteins, cytokines, etc., which are the main material basis for mediating cell crosstalk mechanism. Among them, microRNA carried by cardiac cells-derived exosomes have highly conserved sequences and play a key role in regulating the function of organs, tissues, and cells related to cardiovascular diseases and their complications and comorbidities, which have attracted extensive attention in the medical community in recent years. Following up on the latest research progress at home and abroad, this review systematically summarized the regulatory role of microRNA from cardiac cells-derived exosomes in various cell crosstalk, including not only cardiac cells (including cardiomyocytes, fibroblasts, myofibroblast, cardiac progenitor cells, cardiac microvascular endothelial cells, cardiosphere-derived cells, etc.) but also tumor cells, bone marrow progenitor cells, and other tissue cells, in order to provide a reference for the prevention and treatment of cardiovascular diseases and their complications and comorbidities. [ABSTRACT FROM AUTHOR]

The aging heart is characterized by a number of structural changes leading to ventricular stiffness, impaired resistance to stress and increased risk of developing heart failure (HF). Genetic or pharmacological removal of senescent cells has recently demonstrated the possibility to relieve some cardiac aging features such as hypertrophy and fibrosis. However, the contribution of the different cell types in cardiac aging remains fragmentary due to a lack of cell‐specific markers. Cardiomyocytes undergo post‐mitotic senescence in response to telomere damage, characterized by persistent DNA damage response and expression of the classical senescence markers p21 and p16, which are shared by many other cell types. In the present study, we used transcriptomic approaches to discover new markers specific for cardiomyocyte senescence. We identified Prominin2 (Prom2), encoding a transmembrane glycoprotein, as the most upregulated gene in cardiomyocytes of aged mice compared to young mice. We showed that Prom2 was upregulated by a p53‐dependent pathway in stress‐induced premature senescence. Prom2 expression correlated with cardiomyocyte hypertrophy in the hearts of aged mice and was increased in atrial samples of patients with HF with preserved ejection fraction. Consistently, Prom2 overexpression was sufficient to drive senescence, hypertrophy and resistance to cytotoxic stress while Prom2 shRNA silencing inhibited these features in doxorubicin‐treated cardiac cells. In conclusion, we identified Prom2 as a new player of cardiac aging, linking cardiomyocyte hypertrophy to senescence. These results could provide a better understanding and targeting of cell‐type specific senescence in age‐associated cardiac diseases. [ABSTRACT FROM AUTHOR]

Filamin C (FLNC) is a member of a high-molecular weight protein family, which bind actin filaments in the cytoskeleton of various cells. In human genome FLNC is encoded by the FLNC gene located on chromosome 7 and is expressed predominantly in striated skeletal and cardiac muscle cells. Filamin C is involved in organization and stabilization of thin actin filaments three-dimensional network in sarcomeres, and is supposed to play a role of mechanosensor transferring mechanical signals to different protein targets. Under mechanical stress FLNC can undergo unfolding that increases the risk of its aggregation. FLNC molecules with an impaired native structure could be eliminated by the BAG3-mediated chaperone-assisted selective autophagy. Mutations in the FLNC gene could be accompanied by the changes in FLNC interaction with its protein partners and could lead to formation of aggregates, which overload the autophagy and proteasome protein degradation systems, thus facilitating development of various pathological processes. Molecular mechanisms of the FLNC-associated congenital disorders, called filaminopathies, remain poorly understood. This review is devoted to analysis of the structure and mechanisms of filamin C function in muscle and heart cells in normal state and in the FLNC-associated pathologies. The presented data summarize the results of research at the molecular, cellular, and tissue levels and allow us to outline promising ways for further investigation of pathogenetic mechanisms in filaminopathies. [ABSTRACT FROM AUTHOR]

Intrauterine hypoxia (gestation days 15-19, pO2 65 mm Hg, duration 4 h) led to an increase in the expression of p53, beclin-1, endothelial NO synthase (eNOS), and caspase-3 proteins in cardiomyocytes and reduced the number of mast cells in the heart of 60-day-old albino rats. Administration of a non-opiate analogue of leu-enkephalin (NALE peptide: Phe–D-Ala–Gly–Phe–Leu–Arg, 100 μg/kg) on days 2-6 of the neonatal period decreased the severity of delayed posthypoxic myocardial reaction. The content of eNOS+ cardiomyocytes and the total number of mast cells of these animals did not differ from the control parameters; the content of p53+ cardiomyocytes was significantly lower than in animals exposed to intrauterine hypoxia. The cardioprotective activity of NALE was partially neutralized by co-administration with the NO synthase inhibitor (L-NAME, 50 mg/kg). Correction of the delayed posthypoxic changes, similar to the effects of NALE peptide, was observed after neonatal administration of its arginine-free analogue, G peptide (Phe–D-Ala–Gly–Phe–Leu–Gly; 100 μg/kg). Non-opiate analogues of leu-enkephalin NALE and G peptides can be considered as promising substances capable of preventing long-term cardiac consequences of intrauterine hypoxia. [ABSTRACT FROM AUTHOR]

Mutations in GATA6 are associated with congenital heart disease, most notably conotruncal structural defects. However, how GATA6 regulates cardiac morphology during embryogenesis is undefined. We used knockout and conditional mutant zebrafish alleles to investigate the spatiotemporal role of gata6 during cardiogenesis. Loss of gata6 specifically impacts atrioventricular valve formation and recruitment of epicardium, with a prominent loss of arterial pole cardiac cells, including those of the ventricle and outflow tract. However, there are no obvious defects in cardiac progenitor cell specification, proliferation or death. Conditional loss of gata6 starting at 24 h is sufficient to disrupt the addition of late differentiating cardiomyocytes at the arterial pole, with decreased expression levels of anterior secondary heart field (SHF) markers spry4 and mef2cb. Conditional loss of gata6 in the endoderm is sufficient to phenocopy the straight knockout, resulting in a significant loss of ventricular and outflow tract tissue. Exposure to a Dusp6 inhibitor largely rescues the loss of ventricular cells in gata6−/− larvae. Thus, gata6 functions in endoderm are mediated by FGF signaling to regulate the addition of anterior SHF progenitor derivatives during heart formation. [ABSTRACT FROM AUTHOR]

This study investigates the characteristics of cardiac mesenchymal stem cell-like cells (CMSCLCs) isolated from the right atrial appendage of human donors with ischemia and a young patient with endocarditis (NE-CMSCLCs). Typical CMSCLCs from ischemic heart patients were derived from coronary artery bypass grafting procedures and compared against bone marrow mesenchymal stromal cells (BM-MSCs). NE-CMSCLCs had a normal immunophenotype, but exhibited enhanced osteogenic differentiation potential, rapid proliferation, reduced senescence, reduced glycolysis, and lower reactive oxygen species generation after oxidative stress compared with typical ischemic CMSCLCs. These differences suggest a unique functional status of NE-CMSCLCs, influenced by the donor health condition. Despite large variances in their paracrine secretome, NE-CMSCLCs retained therapeutic potential, as indicated by their ability to protect hypoxia/reoxygenation-injured human cardiomyocytes, albeit less effectively than typical CMSCLCs. This research describes a unique cell phenotype and underscores the importance of donor health status in the therapeutic efficacy of autologous cardiac cell therapy. [ABSTRACT FROM AUTHOR]

This study focused on investigating the mechanism of the astragaloside IV-induced bone marrow mesenchymal stem cell exosome (AS-IV-MSC-exo)/microRNA(miR)-411/HIF-1α axis in affecting vascular neovascularization and protecting cardiac function in myocardial infarction (MI) mice. Exosomes (MSC-exo and AS-IV-MSC-exo) were separated by differential centrifugation and then characterized. MI mouse models were established by left anterior descending coronary artery ligation. Echocardiography was used to evaluate cardiac function. HE staining and Masson staining were performed to observe myocardial histopathology. Capillary density in the myocardium via immunohistochemistry and quantified the expression of vascular endothelial growth factor (VEGF) via RT-qPCR. The expression of miR-411 and HIF-1α was tested by RT-qPCR and western blot and the targeting relationship of miR-411 and HIF-1α was verified by bioinformatics website and dual luciferase reporter gene assay. Exosomes with lipid bi-layer membrane structure, expressing exosomal surface marker proteins, and being taken up by cardiomyocytes could be successfully isolated utilizing ultracentrifugation. Intramyocardial injection of MSC-exo could restore cardiac function, decrease myocardial pathological changes and collagen deposition, and promote neovascularization in MI mice; the effect of AS-IV-MSC-exo was more significant. The ability of AS-IV-MSC-exo to restore cardiac function, lower myocardial pathological changes and collagen deposition, and promote neovascularization in MI mice was diminished when miR-411 expression in AS-IV-MSC-exo was reduced. Mechanistically, miR-411 was found to target and inhibit HIF-1α expression. Overexpression of HIF-1α impaired the impact of AS-IV-MSC-exo on improving cardiac function and promoting neovascularization in MI mice. AS-IV-MSC-exo improves cardiac function and promoted neovascularization via the miR-411/HIF-1α axis, thereby ameliorating MI. [ABSTRACT FROM AUTHOR]

Background: Cardiac involvement in systemic light chain amyloidosis (AL) leads to chronic heart failure and is a major prognosis factor. Severe cellular defects are provoked in cardiac cells by tissue-deposited amyloid fibrils of misfolded free immunoglobulin light chains (LCs) and their prefibrillar oligomeric precursors. Objective: Understanding the molecular mechanisms behind cardiac cell cytotoxicity is necessary to progress in therapy and to improve patient management. One key question is how extracellularly deposited molecules exert their toxic action inside cardiac cells. Here we searched for direct evidence of amyloid LC uptake by cardiomyocytes in patient biopsies. Methods: We immunolocalized LCs in cardiac biopsies from four AL cardiac amyloidosis patients and analysed histopathological images by high resolution confocal microscopy and 3D image reconstruction. Results: We show, for the first time directly in patient tissue, the presence of LCs inside cardiomyocytes, and report their proximity to nuclei and to caveolin-3-rich areas. Our observations point to macropinocytosis as a probable mechanism of LC uptake. Conclusions: Internalisation of LCs occurs in patient cardiomyocytes. This event could have important consequences for the pathogenesis of the cardiac disease by enabling interactions between amyloid molecules and cellular organelles inducing specific signalling pathways, and might bring new insight regarding treatment. [ABSTRACT FROM AUTHOR]

The heart is the first organ formed during mammalian development and functions to distribute nutrients and oxygen to other parts of the developing embryo. Cardiomyocytes are the major cell types of the heart and provide both structural support and contractile function to the heart. The successful differentiation of cardiomyocytes during early development is under tight regulation by physical and molecular factors. We have reviewed current studies on epigenetic factors critical for cardiomyocyte differentiation, including DNA methylation, histone modifications, chromatin remodelers, and noncoding RNAs. This review also provides comprehensive details on structural and morphological changes associated with the differentiation of fetal and postnatal cardiomyocytes and highlights their differences. A holistic understanding of all aspects of cardiomyocyte development is critical for the successful in vitro differentiation of cardiomyocytes for therapeutic purposes. [ABSTRACT FROM AUTHOR]

The increasing prevalence of diabetes and dyslipidemia poses significant health challenges, impacting millions of people globally and leading to high rates of illness and death. This study aimed to explore the potential antidiabetic and hypolipidemic effects of Plu kaow (Houttuynia cordata Thunb.) ethanolic extract (PK) in streptozotocin (STZ) induced diabetic rats, focusing on its molecular mechanisms. Diabetes was induced in fasting Long Evans rats using streptozotocin (65 mg/kg b. w.), with glibenclamide (5 mg/kg/day) used as the standard experimental drug. The treated groups received oral supplementation of PK (500 mg/kg/day) for 28 days. The study evaluated blood glucose levels, lipid status, body weight, liver, kidney, and heart function biomarkers, antioxidant activity, and histological examination of various organs. Additionally, untargeted metabolomics, cheminformatics, and molecular docking were employed to elucidate the probable mechanisms of action of PK. Based on metabolomic profiling data, the PK was found to contain various putative antidiabetic agents such as kaempferol 7-neohesperidoside, isochlorogenic acid C, rutin, datiscin, and diosmin and they have been proposed to significantly (p < 0.001) reduce blood glucose levels and modulated hyperlipidemia. PK also improved the tested liver, kidney, and heart function biomarkers and reversed damage to normal pancreatic, liver, kidney, and heart cells in histological analysis. In conclusion, PK shows promise as a potential treatment or management option for diabetes and hyperlipidemia, as well as their associated complications in diabetic rats. [ABSTRACT FROM AUTHOR]

Decellularized grafts have shown promising results in tissue engineering. The aim of decellularization is to create a scaffold that is devoid of immunogenic components, has natural tissue architecture, and can provide cellularity again. The aim of our study is to obtain a living/regenerative valve by coculture of HUVEC and human dermal fibroblast cells on the pulmonary heart valves of decellularized young sheep and subsequently perform their in vitro characterization to determine its suitability for clinical studies. Various characterization tests were applied to sheep pulmonary heart valves decellularized by the detergent-based method. HUVEC and dermal fibroblast cells were seeded on the scaffold, and their viability was determined by MTT analysis, adhesion by SEM, and cell infiltration by histological staining. Finally, to determine the regenerative ability of the resulting live cap, collagen type I (Col1), collagen type III (Col3), and elastin (Eln) gene expressions were analyzed by PCR. The results showed that cell proliferation increased day by day on the scaffold. In histological findings, it was observed that cellular regeneration was almost completely achieved, especially in arterial wall samples. According to PCR findings, a significant increase in Col1, Col3, and Eln gene expressions was observed in arterial wall samples. In this study, for the first time in the literature, the regeneration potential of differentiated human cells on decellularized sheep heart valves was observed, and markers related to new ECM production were analyzed. In conclusion, we suggest that the decellularized heart valves of young sheep can be used as a starting matrix in tissue engineering studies, and clinical studies are needed. [ABSTRACT FROM AUTHOR]

Metabolic syndrome (MetS) is a condition that includes symptoms, such as obesity, hyperglycemia, and hypertension, which elevate cardiovascular risk. An impaired angiogenic response of endothelial cells (ECs) in heart and peripheral organs has been proposed in MetS, but the mechanisms of this phenomenon have not been thoroughly explored. Results obtained from evaluating the whole myocardium are inconsistent, since different types of cells react differently to MetS environment and a variety of molecular pathways are involved in the angiogenic response. Therefore, the aim of this paper was to study one selected pathway—the VEGF/VEGFR pathway, which regulates the angiogenic response and microvascular permeability in ECs isolated from db/db mouse hearts. The expression of mRNAs for VEGF/VEGFR axis proteins was assessed with RT-PCR in ECs isolated from control and db/db mouse myocardium. The density of CD31-, VEGFR2-, and VE-cadherin-positive cells was examined with confocal microscopy, and the ultrastructure of ECs was analyzed with transmission electron microscopy. The aortic ring assay was used to assess the capacity of ECs to respond to angiogenic stimuli. Our results showed a decreased number of microvessels, diminished expression of VE-cadherin and VEGFR2 and widened gaps between the ECs of microcapillaries. The aortic ring assay showed a diminished number of sprouts in db/db mice. These results may indicate that ECs in MetS enhance the production of mRNA for VEGF/VRGFR axis proteins, yet sprout formation and vascular barrier maintenance are limited. These novel data may provide a foundation for further studies on ECs dysfunction in MetS. [ABSTRACT FROM AUTHOR]

Background: Buyang Huanwu Decoction (BYHWD) is a traditional Chinese medicine to treat the syndrome of qi deficiency and blood stasis. Platelets play an important role in regulating thrombus and inflammation after ischemic injury, studies have shown that BYHWD regulate myocardial fibrosis and exert anti-inflammatory effects through IL-17 and TLR4 pathways, but the mechanism of platelet activation by BYHWD in stable coronary heart disease is still unknown. In the present study, model of left anterior descending coronary artery ligation was applied to investigate the mechanisms of BYHWD on modulating platelets hyperreactivity and heart function after fibrosis of ischemic myocardial infarction (MI). Methods: Myocardial infarction model was constructed by ligation of the left anterior descending coronary artery. The rats were randomly divided into five groups: sham, model, MI with aspirin (positive), MI with a low dosage of BYHWD (BYHWD-ld) and MI with a high dosage of BYHWD (BYHWD-hd) for 28 days. Results: Coronary artery ligation prominently induced left ventricle dysfunction, increased cardiomyocyte fibrosis, which was accompanied by platelets with hyperreactivity, and high levels of inflammatory factors. BYHWD obviously reversed cardiac dysfunction and fibrosis, increased the thickness of the left ventricular wall, and inhibited aggregation ratio and CD62p expression. BYHWD restored the mitochondrial respiration of platelets after MI, concomitant with an increased telomere expression and decreased inflammation. According to the result of transcriptome sequencing, we found that 106 differentially expressed genes compared model with BYHWD treatment. Enrichment analysis screened out the Ras-related protein Rap-1 (Rap1) signaling pathway and platelet activation biological function. Quantitative real-time PCR and Western blotting were applied to found that BYHWD reduced the expression of Rap1/PI3K-Akt/Src-CDC42 genes and attenuated the overactivity of PI3 kinase/Rap1/integrin α(IIb)β(3) pathway. Conclusion: BYHWD reduced inflammation and platelet activation via the PI3 kinase/Rap1/integrin α(IIb)β(3) pathway and improved heart function after MI. [ABSTRACT FROM AUTHOR]

Background People with human immunodeficiency virus (HIV) (PWH) have an increased risk of cardiovascular disease (CVD). Cardiac magnetic resonance (CMR) has documented higher myocardial fibrosis, inflammation, and steatosis in PWH, but studies have mostly relied on healthy volunteers as comparators and focused on men. Methods We investigated the associations of HIV and HIV-specific factors with CMR phenotypes in female participants enrolled in the Women's Interagency HIV Study's New York and San Francisco sites. Primary phenotypes included myocardial native (n) T1 (fibro-inflammation), extracellular volume fraction (fibrosis), and triglyceride content (steatosis). Associations were evaluated with multivariable linear regression, and results pooled or meta-analyzed across centers. Results Among 261 women with HIV (WWH, N = 362), 76.2% had undetectable viremia at CMR. For the 82.8% receiving continuous antiretroviral therapy (ART) in the preceding 5 years, adherence was 51.7%, and 69.4% failed to achieve persistent viral suppression (40.7% with peak viral load <200 cp/mL). Overall, WWH showed higher nT1 than women without HIV after full adjustment. This higher nT1 was more pronounced in those with antecedent or current viremia or nadir CD4+ count <200 cells/μL, with the latter also associated with higher extracellular volume fraction. WWH and current CD4+ count <200 cells/μL had less cardiomyocyte steatosis. Cumulative exposure to specific ART showed no associations. Conclusions Compared with sociodemographically similar women without HIV, WWH on ART exhibit higher myocardial fibro-inflammation, which is more prominent with unsuppressed viremia or CD4+ lymphopenia. These findings support the importance of improved ART adherence strategies, along with better understanding of latent infection, to mitigate cardiac end-organ damage in this population. [ABSTRACT FROM AUTHOR]

A recent study published in Cell Discovery explores the potential of chimeric antigen receptor macrophages (CAR-M) in targeting cardiac fibrosis. The researchers developed a CAR strategy to direct macrophages to engulf fibroblast activation protein (FAP)-expressing myofibroblasts, which are associated with cardiac fibrosis. In vitro experiments demonstrated that CAR-M cells effectively phagocytosed FAP+ target cells. In a mouse model of hypertensive cardiac injury, adoptive transfer of CAR-M cells reduced cardiac fibrosis and improved heart function. The study suggests that CAR-M cells have therapeutic potential for treating cardiac fibrosis, although further research is needed to optimize the CAR-M strategy and explore other phagocytic receptors. [Extracted from the article]

In recent years, research on organ-on-a-chip technology has been flourishing, particularly for drug screening and disease model development. Fibroblasts and vascular endothelial cells engage in crosstalk through paracrine signaling and direct cell–cell contact, which is essential for the normal development and function of the heart. Therefore, to faithfully recapitulate cardiac function, it is imperative to incorporate fibroblasts and vascular endothelial cells into a heart-on-a-chip model. Here, we report the development of a human heart-on-a-chip composed of induced pluripotent stem cell (iPSC)-derived cardiomyocytes, fibroblasts, and vascular endothelial cells. Vascular endothelial cells cultured on microfluidic channels responded to the flow of culture medium mimicking blood flow by orienting themselves parallel to the flow direction, akin to in vivo vascular alignment in response to blood flow. Furthermore, the flow of culture medium promoted integrity among vascular endothelial cells, as evidenced by CD31 staining and lower apparent permeability. The tri-culture condition of iPSC-derived cardiomyocytes, fibroblasts, and vascular endothelial cells resulted in higher expression of the ventricular cardiomyocyte marker IRX4 and increased contractility compared to the bi-culture condition with iPSC-derived cardiomyocytes and fibroblasts alone. Such tri-culture-derived cardiac tissues exhibited cardiac responses similar to in vivo hearts, including an increase in heart rate upon noradrenaline administration. In summary, we have achieved the development of a heart-on-a-chip composed of cardiomyocytes, fibroblasts, and vascular endothelial cells that mimics in vivo cardiac behavior. [ABSTRACT FROM AUTHOR]

Abstract\nKey points:Type 2 Diabetes mellitus (T2DM) has the potential to impair cardiac function and cause heart failure. We aimed to study the cardioprotective influence of Galactin-3 (Gal-3) inhibitor; modified citrus pectin (MCP) in isoprenaline induced myocardial infarction (MI) in T2DM rats. Forty rats were allocated into 4 groups; groups I and II served as control. T2DM was provoked in groups III and IV by serving them high fat diet followed by a single low dose of Streptozotocin (STZ), then group IV were administered MCP in drinking water for 6 weeks. Groups III and IV were then subcutaneously injected isoprenaline hydrochloride once daily on the last 2 successive days to induce MI. MCP restored echocardiographic parameters with significant decline in Gal-3 area % in cardiac tissue alongside protection against cardiac remodelling. our data showed that there is a protective potential for Gal-3 inhibitor (MCP) against cardiac injury in isoprenaline induced MI in T2DM.Type 2 Diabetes mellitus (T2DM) has the potential to impair cardiac function and cause heart failure (HF).Gal-3 inhibition with MCP for 6 weeks caused effective protection against cardiac fibrosis, LV dysfunction, and ensuing heart failure progress in type 2 diabetic rats with an isoprenaline-induced myocardial infarction.The defending effect of Gal-3 inhibitor; MCP seems to be exerted by modulating cardiac cell response to injury, through decreasing incidence of cardiac inflammation, oxidative stress, apoptosis and decreased cardiac Gal-3 immuno-reactivity. [ABSTRACT FROM AUTHOR]

Background: The heart is a contractile organ with the ability to generate its own signals. Because of the excitable nature of heart cells, they may be impacted by external impulses or stimuli. The purpose of this research is to use electrocardiogram (ECG) measurements to ascertain the effects of exposure to an extremely low frequency pulsed magnetic field (ELF-PEMF) at 1 milli Tesla (mT) and 5 mT intensity on the heart's electrical stimulation system. Materials and Methods: Eighteen Wistar Albino rats, weighing 200-250g and aged 8 weeks, were randomly allocated into three groups, with six rats in each group: sham, 1 milli Tesla (1 mT), and 5 mT exposure groups. Rats were subjected to ELF-PEMF for 4-hours each day, 5-days per week for 8-weeks. The rats in the sham group were kept under the same condition, but the exposure system was turned off. Results: The findings indicate that ELF-PEMF exposure at 1 mT and 5 mT intensities did not affect common ECG parameters used to evaluate cardiac rhythmic activity, including heart rate, P-wave amplitude, PR interval, QRS interval, R amplitude, and QT interval. Conclusion: The 8-week exposure to ELF-PEMF at the 1 mT and 5 mT intensities didn’t show any effect on ECG parameters in rats, at least according to the design applied in this study. The effects of these magnetic fields are also directly related to exposure durations and intensity. Therefore, more research is required to ascertain how varied application intensities and durations affect cardiac function. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms underlying vascular regeneration in the heart is crucial for developing novel therapeutic strategies for myocardial ischemia. This study investigates the contribution of bone marrow-derived cells to endothelial cell populations in the heart, and their role in cardiac function and coronary circulation following repetitive ischemia (RI). Chimeric rats were created by transplanting BM cells from GFP female rats into irradiated male recipients. After engraftment chimeras were subjected to RI for 17 days. Vascular growth was assessed from recovery of cardiac function and increases in myocardial blood flow during LAD occlusion. After sorting GFP+ BM cells from heart and bone of Control and RI rats, single-cell RNA sequencing was implemented to determine the fate of BM cells. Our in vivo RI model demonstrated an improvement in cardiac function and myocardial blood flow after 17 days of RI with increased capillary density in the rats subjected to RI compared to Controls. Single-cell RNA sequencing of bone marrow cells isolated from rats' hearts identified distinct endothelial cell (EC) subpopulations. These ECs exhibited heterogeneous gene expression profiles and were enriched for markers of capillary, artery, lymphatic, venous, and immune ECs. Furthermore, BM-derived ECs in the RI group showed an angiogenic profile, characterized by upregulated genes associated with blood vessel development and angiogenesis. This study elucidates the heterogeneity of bone marrow-derived endothelial cells in the heart and their response to repetitive ischemia, laying the groundwork for targeting specific subpopulations for therapeutic angiogenesis in myocardial ischemia. [ABSTRACT FROM AUTHOR]