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Background: Currently, there is no effective therapy for takotsubo syndrome (stress‐induced cardiac injury in humans) in the clinics. It has previously been shown that β2‐adrenergic receptor (β2‐AR) agonist formoterol reduces cardiomyocyte injury in experimental takotsubo syndrome. Objectives: The aim of this study was to investigate whether formoterol prevents apoptosis and necrosis of cardiomyocytes and endothelial cells in stress‐induced cardiomyopathy. Methods: Stress‐induced cardiac injury was induced by immobilization of rats for 2, 6, and 24 hours. Results: The myocardium of stressed rats showed a reduction in contractility and histological manifestations of cardiomyocyte damage: karyopyknosis, perinuclear edema of cardiomyocytes and endothelial cells, and microcirculation disturbances augmented with extended exposure to stress. In addition, apoptosis of endothelial cells was detected 6 hours after the onset of stress and peaked at 24 hours. Apoptosis of cardiomyocytes significantly gained only after 24 hours of stress exposure. These morphological alterations were associated with increased levels of serum creatine kinase‐MB, syndecan‐1, and thrombomodulin after 24 hours of stress. Administration of β2‐AR agonist formoterol (50 μg/kg) four times during 24‐hour stress exposure led to the improvement in myocardial inotropy, decrease in the severity of histological signatures, reduction in the number of TUNEL‐positive cardiomyocytes, serum creatine kinase‐MB, syndecan‐1, and thrombomodulin levels. Conclusion: Present data suggest that apoptosis and necrosis of cardiomyocytes and necrosis of endothelial cells in stress‐induced cardiac injury can be mitigated by activation of the β2‐AR. However, formoterol did not eliminate completely cardiomyocyte apoptosis, histological alterations, or endothelium injury markers under stress. [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]

AbstractHeart failure is described as a complicated syndrome, which is estimated that 56.2 million people were living with HF globally in 2019. Oxidative stress and apoptosis play a major role on HF development via targeting several signaling pathways in cardiac cells. This study investigated medicinal plants or their bioactive components with positive effects on HF management. In this research, keywords “heart failure,” “plant,” “antioxidant” or “radical scavenging,” “herbal” and “apoptosis” were synchronously searched through popular databases from 1990 up to 2023. Finally, the role of oxidative stress and apoptosis in HF development was searched and related signaling pathways were investigated. [ABSTRACT FROM AUTHOR]

Background: Congenital heart defects can lead to right ventricular (RV) pressure-overload and heart failure. Cell-based therapies, including mesenchymal stromal cells (MSCs) and c-kit positive cells (CPCs) have been studied clinically as options to restore heart function in disease states. Many studies have indicated these cells act through paracrine mechanisms to prevent apoptosis, promote cellular function, and regulate gene/protein expression. We aimed to determine the proteomic response of diseased hearts to cell therapy. Methods: We utilized a juvenile rat model of RV pressure overload created by banding the pulmonary artery (PAB). Two weeks post-banding, bone marrow-derived mesenchymal stromal cells (MSCs) and 3 populations of CPCs (nCPCs, cCPCs, ES-CPCs) were delivered to the RV free wall. RV function and cellular retention were measured for four weeks post-injection, at which point hearts were extracted and the RV was excised for liquid chromatography and tandem mass spectrometry. Resulting RV proteomes were compared and analyzed using systems biology and bioinformatics. Results: Proteomic profiling identified 1156 total proteins from the RV, of which 5.97% were significantly changed after PAB. This disease-altered proteome was responsive to cellular therapy, with 72% of the PAB-altered proteome being fully or partially reversed by MSC therapy. This was followed by nCPCs (54%), ES-CPCs (52%), and cCPCs (39%). Systems biology and bioinformatics analysis showed MSC, nCPC, or ES-CPC cell therapy is associated with a decrease in predicted adverse cardiac effects. We also observed an effect of cell therapy on the non-altered RV proteome, however, this was associated with minor predicted pathological endpoints. Conclusions: Our data indicate MSCs, ES-CPCs, and nCPCs significantly reverse the PAB-altered proteome towards a pre-disease state in our animal model. These results indicate cell-based therapies show promise in improving RV function after pressure overload through partial restoration of the disease-altered cardiac proteome. [ABSTRACT FROM AUTHOR]

Purpose. This study aimed to investigate the impacts of tanshinone IIA (Tan IIA) on ischemia/reperfusion (I/R)‐induced cardiomyocyte injury in coronary heart disease (CHD), and to determine whether Tan IIA regulates myocardial cell injury induced by I/R through the Hyaluronan Synthase 2/fibroblast growth factor 9 (HAS2/FGF9) axis. Methods. Weighted gene co‐expression network analysis (WGCNA) of the GSE23561 microarray dataset determined gene modules linked to CHD. The key genes were further explored through differential expression and protein‐protein interaction (PPI) network analyses. Human AC16 cardiomyocytes were treated with Tan IIA, HAS2 knockdown, and FGF9 overexpression and they were exposed to normoxic, hypoxic, and I/R environments. Cell viability, apoptosis, gene/protein expression, and markers of oxidative stress were evaluated in vitro. Results. The turquoise module was significantly correlated with CHD and HAS2 was identified as a hub gene. Under hypoxic conditions, Tan IIA exhibited a dose‐dependent cardioprotective effect. Tan IIA ameliorated I/R‐induced cellular injury, as evidenced by increased cell viability, decreased apoptosis, and regulation of key proteins (PCNA, Bax). After I/R conditions, knockdown of HAS2 increased cell viability and reduced apoptosis, whereas overexpression of FGF9 reversed these effects. Notably, HAS2 knockdown also ameliorated I/R‐induced increases in inflammatory cytokines and oxidative stress, and synergistic protection was provided by combined treatment with FGF9 and Tan IIA. Conclusion. Taken together, our findings confirm that Tan IIA protects cardiomyocytes from I/R‐induced injury by controlling the HAS2/FGF9 axis. These findings reveal the potential therapeutic significance of Tan IIA in alleviating CHD‐related myocardial dysfunction. [ABSTRACT FROM AUTHOR]

Cardiac regenerative potential in the animal kingdom displays striking divergence across ontogeny and phylogeny. Here we discuss several fundamental questions in heart regeneration and provide both a holistic view of heart regeneration in the organism as a whole, as well as a single-cell perspective on intercellular communication among diverse cardiac cell populations. We hope to provide valuable insights that advance our understanding of organ regeneration and future therapeutic strategies. [ABSTRACT FROM AUTHOR]

Oxidative stress promotes T. cruzi growth and development of chronic Chagas heart dysfunction. However, the literature contains gaps that must be fulfilled, largely due to variations in parasite DTU sources, cell types, mouse strains, and tools to manipulate redox status. We assessed the impact of oxidative environment on parasite burden in cardiomyoblasts and the effects of the Nrf2-inducer COPP on heart function in BALB/c mice infected with either DTU-II Y or DTU-I Colombian T. cruzi strains. Treatment with antioxidants CoPP, apocynin, resveratrol, and tempol reduced parasite burden in cardiomyoblasts H9C2 for both DTUI- and II-strains, while H2O2 increased it. CoPP treatment improved electrical heart function when administered during acute stage of Y-strain infection, coinciding with an overall trend towards increased survival and reduced heart parasite burden. These beneficial effects surpassed those of trypanocidal benznidazole, implying that CoPP directly affects heart physiology. CoPP treatment had beneficial impact on heart systolic function when performed during acute and evaluated during chronic stage. No impact of CoPP on heart parasite burden, electrical, or mechanical function was observed during the chronic stage of Colombian-strain infection, despite previous demonstrations of improvement with other antioxidants. Treatment with CoPP also did not improve heart function of mice chronically infected with Y-strain. Our findings indicate that amastigote growth is responsive to changes in oxidative environment within heart cells regardless of the DTU source, but CoPP influence on heart parasite burden in vivo and heart function is mostly confined to the acute phase. The nature of the antioxidant employed, T. cruzi DTU, and the stage of disease, emerge as crucial factors to consider in heart function studies. Author summary: Chagas disease, caused by Trypanosoma cruzi, can lead to serious heart complications, known as Chagas cardiomyopathy. This study investigates the role of oxidative stress on the growth of T. cruzi and the effects of antioxidants, particularly protoporphyrin cobalt (CoPP), on heart health using two distinct strains of the parasite (Y and Colombian strains). We found that CoPP and other antioxidants, including apocynin, resveratrol, and tempol, reduced parasite levels in heart cells, while oxidative stress increased it. In mice infected with the Y strain of T. cruzi, CoPP treatment during the acute phase improved heart function, reduced parasite burden, and increased survival, outperforming the standard treatment with benznidazole. However, CoPP's benefits were mostly confined to the early stages of infection. When treatment was administered during the chronic phase, it did not improve heart function or reduce parasite levels in mice infected with the Colombian strain, despite previous studies showing that other antioxidants can be beneficial in this stage. These findings suggest that the type of antioxidant and the timing of treatment are crucial in managing Chagas disease. This work underscores the potential of early antioxidant treatments like CoPP to protect heart function and prevent long-term damage, potentially offering better treatment strategies. [ABSTRACT FROM AUTHOR]

Cardiac cell damage frequently occurs as a consequence of acute myocardial infarction (AMI), a critical complication of coronary atherosclerotic heart disease. There is an escalating recognition of the association between COX2 and myocardial damage induced by ischemia. The objective of this study is to investigate the inhibitory effect of the COX2 on cardiomyocyte damage in the context of AMI. To create an AMI model, mice with the genetic background of wild-type C57BL6/J (WT) and COX2-/- mice were utilized. The left anterior descending (LAD) coronary artery in their hearts was obstructed, and subsequent assessment of hemodynamic parameters and heart function was conducted. Notably, increased levels of COX2 were observed in AMI mice. Through correlational analysis between COX2 expression and cardiac function following AMI, it was revealed that COX2 knockout mice had smaller infarct sizes, better cardiac performance, and suppressed levels of reactive oxygen species (ROS) compared to WT mice. Additionally, we discovered that COX2 knockout mice exhibited significantly higher mRNA levels of smooth muscle actin, collagen I, and collagen III than normal mice with AMI. Conversely, the levels of superoxide dismutase (SOD), malondialdehyde (MDA) were higher but iron content was decreased in COX2 knockout mice compared to normal mice with AMI.In summary, our research demonstrates that the downregulation of COX2 enhances cardiac tissue recovery in the context of AMI. [ABSTRACT FROM AUTHOR]

BACKGROUND: Metabolic distress is often associated with heart failure with preserved ejection fraction (HFpEF) and represents a therapeutic challenge. Metabolism-induced systemic inflammation links comorbidities with HFpEF. How metabolic changes affect myocardial inflammation in the context of HFpEF is not known. METHODS: We found that ApoE knockout mice fed a Western diet recapitulate many features of HFpEF. Single-cell RNA sequencing was used for expression analysis of CD45+ cardiac cells to evaluate the involvement of inflammation in diastolic dysfunction. We focused bioinformatics analysis on macrophages, obtaining high-resolution identification of subsets of these cells in the heart, enabling us to study the outcomes of metabolic distress on the cardiac macrophage infiltrate and to identify a macrophage-to-cardiomyocyte regulatory axis. To test whether a clinically relevant sodium glucose cotransporter-2 inhibitor could ameliorate the cardiac immune infiltrate profile in our model, mice were randomized to receive the sodium glucose cotransporter-2 inhibitor dapagliflozin or vehicle for 8 weeks. RESULTS: ApoE knockout mice fed a Western diet presented with reduced diastolic function, reduced exercise tolerance, and increased pulmonary congestion associated with cardiac lipid overload and reduced polyunsaturated fatty acids. The main immune cell types infiltrating the heart included 4 subpopulations of resident and monocyte-derived macrophages, determining a proinflammatory profile exclusively in ApoE knockout-Western diet mice. Lipid overload had a direct effect on inflammatory gene activation in macrophages, mediated through endoplasmic reticulum stress pathways. Investigation of the macrophage-to-cardiomyocyte regulatory axis revealed the potential effects on cardiomyocytes of multiple inflammatory cytokines secreted by macrophages, affecting pathways such as hypertrophy, fibrosis, and autophagy. Finally, we describe an anti-inflammatory effect of sodium glucose cotransporter-2 inhibition in this model. CONCLUSIONS: Using single-cell RNA sequencing in a model of diastolic dysfunction driven by hyperlipidemia, we have determined the effects of metabolic distress on cardiac inflammatory cells, in particular on macrophages, and suggest sodium glucose cotransporter-2 inhibitors as potential therapeutic agents for the targeting of a specific phenotype of HFpEF. [ABSTRACT FROM AUTHOR]

The vertebrate heart tube extends by progressive addition of epithelial second heart field (SHF) progenitor cells from the dorsal pericardial wall. The interplay between epithelial mechanics and genetic mechanisms during SHF deployment is unknown. Here, we present a quantitative single-cell morphometric analysis of SHF cells during heart tube extension, including force inference analysis of epithelial stress. Joint spatial Principal Component Analysis reveals that cell orientation and stress direction are the main parameters defining apical cell morphology and distinguishes cells adjacent to the arterial and venous poles. Cell shape and mechanical forces display a dynamic relationship during heart tube formation. Moreover, while the T-box transcription factor Tbx1 is necessary for cell orientation towards the arterial pole, activation of Tbx5 in the posterior SHF correlates with the establishment of epithelial stress and SHF deletion of Tbx5 relaxes the progenitor epithelium. Integrating findings from cell-scale feature patterning and mechanical stress provides new insights into cardiac morphogenesis. The embryonic heart tube undergoes elongation via the addition of progenitors from the second heart field, though how epithelial mechanics and genetics interact during this process remains unknown. Here they use quantitative morphometric analysis to reveal that Tbx5 regulates epithelial tension in the posterior region of the second heart field. [ABSTRACT FROM AUTHOR]

Impaired tissue regeneration negatively impacts on left ventricular (LV) function and remodeling after acute myocardial infarction (AMI). Little is known about the intrinsic regulatory machinery of ischemia-induced endogenous cardiac stem cells (eCSCs) self-renewing divisions after AMI. The interleukin 22 (IL-22)/IL-22 receptor 1 (IL-22R1) pathway has emerged as an important regulator of several cellular processes, including the self-renewal and proliferation of stem cells. However, whether the hypoxic environment could trigger the self-renewal of eCSCs via IL-22/IL-22R1 activation remains unknown. In this study, the upregulation of IL-22R1 occurred due to activation of hypoxia-inducible factor-1α (HIF-1α) under hypoxic and ischemic conditions. Systemic IL-22 administration not only attenuated cardiac remodeling, inflammatory responses, but also promoted eCSC-mediated cardiac repair after AMI. Unbiased RNA microarray analysis showed that the downstream mediator Bmi1 regulated the activation of CSCs. Therefore, the HIF-1α-induced IL-22/IL-22R1/Bmi1 cascade can modulate the proliferation and activation of eCSCs in vitro and in vivo. Collectively, investigating the HIF-1α-activated IL-22/IL-22R1/Bmi1 signaling pathway might offer a new therapeutic strategy for AMI via eCSC-induced cardiac repair. [ABSTRACT FROM AUTHOR]

Cardiometabolic disorders contribute to the global burden of cardiovascular diseases. Emerging sphingolipid metabolites like sphingosine‐1‐phosphate (S1P) and its receptors, S1PRs, present a dynamic signalling axis significantly impacting cardiac homeostasis. S1P's intricate mechanisms extend to its transportation in the bloodstream by two specific carriers: high‐density lipoprotein particles and albumin. This intricate transport system ensures the accessibility of S1P to distant target tissues, influencing several physiological processes critical for cardiovascular health. This review delves into the diverse functions of S1P and S1PRs in both physiological and pathophysiological conditions of the heart. Emphasis is placed on their diverse roles in modulating cardiac health, spanning from cardiac contractility, angiogenesis, inflammation, atherosclerosis and myocardial infarction. The intricate interplays involving S1P and its receptors are analysed concerning different cardiac cell types, shedding light on their respective roles in different heart diseases. We also review the therapeutic applications of targeting S1P/S1PRs in cardiac diseases, considering existing drugs like Fingolimod, as well as the prospects and challenges in developing novel therapies that selectively modulate S1PRs. [ABSTRACT FROM AUTHOR]

Myocardial infarction (MI) is a critical global health issue and a leading cause of heart failure. Indeed, while neonatal mammals can regenerate cardiac tissue mainly through cardiomyocyte proliferation, this ability is lost shortly after birth, resulting in the adult heart's inability to regenerate after injury effectively. In adult mammals, the adverse cardiac remodelling, which compensates for the loss of cardiac cells, impairs cardiac function due to the non-contractile nature of fibrotic tissue. Moreover, the neovascularisation after MI is inadequate to restore blood flow to the infarcted myocardium. This review aims to synthesise the most recent insights into the molecular and cellular players involved in endogenous myocardial and vascular regeneration, facilitating the identification of mechanisms that could be targeted to trigger cardiac regeneration, reduce fibrosis, and improve functional recovery post-MI. Reprogramming adult cardiomyocytes to regain their proliferative potential, along with the modulation of target cells responsible for neovascularisation, represents promising therapeutic strategies. An updated overview of endogenous mechanisms that regulate both myocardial and coronary vasculature regeneration—including stem and progenitor cells, growth factors, cell cycle regulators, and key signalling pathways—could help identify new critical intervention points for therapeutic applications. [ABSTRACT FROM AUTHOR]

Retinoic-acid-related orphan receptors (RORs) are transcription factors belonging to the nuclear receptor subfamily consisting of RORα, RORβ, and RORγ. By binding to the ROR response elements (ROREs) on target gene promoters, RORs regulate a wide variety of cellular processes, including autophagy, mitophagy, oxidative stress, and inflammation. The regulatory roles of RORs are observed in cardiac cells, hepatocytes, pulmonary epithelial cells, renal cells, immune cells, and cancer cells. A growing body of clinical and experimental evidence suggests that ROR expression levels are markedly reduced under different pathological and stress conditions, suggesting that RORs may play a critical role in the pathogenesis of a variety of disease states, including myocardial infarction, immune disorders, cancer, and metabolic syndrome. Reductions in RORs are also associated with inhibition of autophagy, increased reactive oxygen species (ROS), and increased cell death, underscoring the importance of RORs in the regulation of these processes. Herein, we highlight the relationship between RORs and homeostatic processes that influence cell viability. Understanding how these intricate processes are governed at the cellular level is of high scientific and clinical importance to develop new therapeutic strategies that modulate ROR expression and disease progression. [ABSTRACT FROM AUTHOR]

Human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are advancing cardiovascular development and disease modeling, drug testing, and regenerative therapies. However, hPSC-CM production is hindered by significant variability in the differentiation process. Establishment of early quality markers to monitor lineage progression and predict terminal differentiation outcomes would address this robustness and reproducibility roadblock in hPSC-CM production. An integrated transcriptomic and epigenomic analysis assesses how attributes of the cardiac progenitor cell (CPC) affect CM differentiation outcome. Resulting analysis identifies predictive markers of CPCs that give rise to high purity CM batches, including TTN , TRIM55 , DGKI, MEF2C, MAB21L2, MYL7 , LDB3 , SLC7A11, and CALD1. Predictive models developed from these genes provide high accuracy in determining terminal CM purities at the CPC stage. Further, insights into mechanisms of batch failure and dominant non-CM cell types generated in failed batches are elucidated. Namely EMT, MAPK, and WNT signaling emerge as significant drivers of batch divergence, giving rise to off-target populations of fibroblasts/mural cells, skeletal myocytes, epicardial cells, and a non-CPC SLC7A11+ subpopulation. This study demonstrates how integrated multi-omic analysis of progenitor cells can identify quality attributes of that progenitor and predict differentiation outcomes, thereby improving differentiation protocols and increasing process robustness. [Display omitted] • Genes that predict cardiac progenitor cell differentiation to cardiomyocytes. • Early epigenetic fate priming to cardiomyocyte fate in cardiac progenitor cells. • Progenitor-stage, gene-based predictive models for cardiomyocyte purity outcomes. [ABSTRACT FROM AUTHOR]

Myocardial infarction (MI), which causes irreversible myocardium necrosis, affects 0.25 billion people globally and has become one of the most significant epidemics of our time. Over the past few years, bioprinting has moved beyond a concept of simply incorporating cells into biomaterials, to strategically defining the microenvironment (e.g., architecture, biomolecular signalling, mechanical stimuli, etc.) within which the cells are printed. Among the different bioprinting applications, myocardial repair is a field that has seen some of the most significant advances towards the management of the repaired tissue microenvironment. This review critically assesses the most recent biomedical innovations being carried out in cardiac patch bioprinting, with specific considerations given to the biomaterial design parameters, growth factors/cytokines, biomechanical and bioelectrical conditioning, as well as innovative biomaterial-based "4D" bioprinting (3D scaffold structure + temporal morphology changes) of myocardial tissues, immunomodulation and sustained delivery systems used in myocardium bioprinting. Key challenges include the ability to generate large quantities of cardiac cells, achieve high-density capillary networks, establish biomaterial designs that are comparable to native cardiac extracellular matrix, and manage the sophisticated systems needed for combining cardiac tissue microenvironmental cues while simultaneously establishing bioprinting technologies yielding both high-speed and precision. This must be achieved while considering quality assurance towards enabling reproducibility and clinical translation. Moreover, this manuscript thoroughly discussed the current clinical translational hurdles and regulatory issues associated with the post-bioprinting evaluation, storage, delivery and implantation of the bioprinted myocardial patches. Overall, this paper provides insights into how the clinical feasibility and important regulatory concerns may influence the design of the bioink (biomaterials, cell sources), fabrication and post-fabrication processes associated with bioprinting of the cardiac patches. This paper emphasizes that cardiac patch bioprinting requires extensive collaborations from imaging and 3D modelling technical experts, biomaterial scientists, additive manufacturing experts and healthcare professionals. Further, the work can also guide the field of cardiac patch bioprinting moving forward, by shedding light on the potential use of robotics and automation to increase productivity, reduce financial cost, and enable standardization and true commercialization of bioprinted cardiac patches. The manuscript provides a critical review of important themes currently pursued for heart patch bioprinting, including critical biomaterial design parameters, physiologically-relevant cardiac tissue stimulations, and newly emerging cardiac tissue bioprinting strategies. This review describes the limited number of studies, to date in the literature, that describe systemic approaches to combine multiple design parameters, including capabilities to yield high-density capillary networks, establish biomaterial composite designs similar to native cardiac extracellular matrix, and incorporate cardiac tissue microenvironmental cues, while simultaneously establishing bioprinting technologies that yield high-speed and precision. New tools such as artificial intelligence may provide the analytical power to consider multiple design parameters and identify an optimized work-flow(s) for enabling the clinical translation of bioprinted cardiac patches. [Display omitted] [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the mechanism of EMP1 action in high glucose (HG)‐induced H9c2 cardiac cell pyroptosis and oxidative injury. Rat cardiomyocytes H9c2 were exposed to 33 mM glucose for 24, 48, or 72 h to induce cytotoxicity. EMP1‐siRNA, NLRP3 agonist Nigericin, and pcNDA‐RAS were used to treat H9c2 cells under HG conditions. Cell Counting Kit (CCK)‐8 assay showed that cell proliferation was decreased following HG induction, which was rescued by EMP1 knockdown. Our results also suggested that EMP1 siRNA transfection significantly decreased the apoptosis and pyroptosis of HG‐induced cells, as indicated by the reduction of NLRP3 IL‐1β, ASC, GSDMD, cleaved‐caspase1 and cleaved‐caspase3 levels in HG‐induced H9c2 cells. In addition, EMP1 knockdown alleviated HG‐induced mitochondrial damage and oxidative stress in H9c2 cells. NLRP3 activation reversed the inhibitory effects of EMP1 knockdown on pyroptosis and oxidative stress in HG‐induced H9c2 cells. Mechanistically, we found that EMP1 knockdown suppressed the RAS/RAF/MAPK signaling pathway in HG‐induced H9c2 cells. RAS overexpression blocked the protective effect of EMP1 knockdown on HG‐induced H9c2 cell apoptosis, pyroptosis, and oxidative injury. Our findings suggest that EMP1 knockdown treatment might provide a novel therapy for diabetic cardiomyopathy. [ABSTRACT FROM AUTHOR]

Cardiovascular diseases have been the leading cause of global mortality and disability. In addition to traditional drug and surgical treatment, more and more studies investigate tissue engineering therapeutic strategies in cardiovascular medicine. Collagen interweaves in the form of trimeric chains to form the physiological network framework of the extracellular matrix of cardiac and vascular cells, possessing excellent biological properties (such as low immunogenicity and good biocompatibility) and adjustable mechanical properties, which renders it a vital tissue engineering biomaterial for the treatment of cardiovascular diseases. In recent years, promising advances have been made in the application of collagen materials in blood vessel prostheses, injectable cardiac hydrogels, cardiac patches, and hemostatic materials, although their clinical translation still faces some obstacles. Thus, we reviewed these findings and systematically summarizes the application progress as well as problems of clinical translation of collagen biomaterials in the cardiovascular field. The present review contributes to a comprehensive understanding of the application of collagen biomaterials in cardiovascular medicine. [ABSTRACT FROM AUTHOR]

Receptors for activated C kinases (RACKs) have been shown to coordinate PKC-mediated hypertrophic signalling in mice. However, little information is available on its participation in embryonic gene expression. This study investigated the involvement of RACK1 in the expression of embryonic genes in a zebrafish (ZF) ex vivo heart culture model by using phenylephrine (PE) or a growth factors cocktail (GFs) as a prohypertrophic/regeneration stimulus. Blebbistatin (BL) inhibition has also been studied for its ability to block the signal transduction actions of some PEs. qRT‒PCR and immunoblot analyses confirmed the upregulation of RACK1 in the PE- and GFs-treated groups. BL administration counteracted PE-induced hypertrophy and downregulated RACK1 expression. Immunohistochemical analyses of the heart revealed the colocalization of RACK1 and embryonic genes, namely, Gata4, Wt1, and Nfat2, under stimulation, whereas these genes were expressed at lower levels in the BL treatment group. Culturing ZF heart cells activated via GFs treatment increased the expression of RACK1. The overexpression of RACK1 induced by the transfection of recombinant RACK1 cDNA in ZF heart cells increased the expression of embryonic genes, especially after one week of GFs treatment. In summary, these results support the involvement of RACK1 in the induction of embryonic genes during cardiac hypertrophy/GFs stimulation in a fish heart model, which can be used as an alternative study model for mammals. [ABSTRACT FROM AUTHOR]

Camels possess exceptional adaptability, allowing them to withstand extreme temperatures in desert environments. They conserve water by reducing their metabolic rate and regulating body temperature. The heart of the camel plays a crucial role in this adaptation, with specific genes expressed in cardiac tissue that are essential for mammalian adaptation, regulating cardiac function and responding to environmental stressors. One such gene, nebulin‐related‐anchoring protein (NRAP), is involved in the assembly of myofibrils and the transmission of force within the heart. In our study of the NRAP gene across various livestock species, including three camel species, we identified a camel‐specific exon region in the NRAP transcripts. This additional exon (exon 4) contains an open reading frame predicted in camels. To investigate its function, we generated knock‐in mice expressing camel NRAP exon 4. These ‘camelized mice’ exhibited normal phenotypic characteristics compared with wild‐type mice but showed elevated body temperatures under cold stress. Transcriptome analyses of the hearts from camelized mice under cold stress revealed differentially expressed inflammatory cytokine genes, known to influence cardiac function by modulating the contractility of cardiac muscle cells. We propose further investigations utilizing these camelized mice to explore these findings in greater depth. [ABSTRACT FROM AUTHOR]

Cardiac arrhythmias stemming from abnormal sinoatrial node (SAN) function can lead to sudden death. Developing a biological pacemaker device for treating sick sinus syndrome (SSS) could offer a potential cure. Understanding SAN differentiation is crucial, yet its regulatory mechanism remains unclear. We reanalyzed published RNA‐seq data and identified Odz4 as a SAN‐specific candidate. In situ hybridization revealed Odz4 expression in the cardiac crescent and throughout the cardiac conduction system (CCS). To assess the role of Odz4 in CCS differentiation, we utilized a Tet‐Off inducible system for its intracellular domain (ICD). Embryonic bodies (EBs) exogenously expressing Odz4‐ICD exhibited an increased propensity to develop into pacemaker‐like cells with enhanced automaticity and upregulated expression of SAN‐specific genes. CellChat and GO analyses unveiled SAN‐specific enrichment of ligand–receptor sets, especially Ptn‐Ncl, and extracellular matrix components in the group exogenously expressing Odz4‐ICD. Our findings underscore the significance of Odz4 in SAN development and offer fresh insights into biological pacemaker establishment. [ABSTRACT FROM AUTHOR]

AbstractPurposeMethodsResultsConclusionsCardiovascular 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.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.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.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]

Simple Summary: Scientists have developed new techniques that allow them to study the heart at an incredibly detailed level, focusing on individual cells rather than looking at groups of cells together. This is important because the heart is made up of many different types of cells, each with its own role, and understanding how they interact is key to discovering what happens in both healthy hearts and in heart disease. By using methods that look at the genes, proteins, and other molecules inside single cells, researchers can uncover how cells communicate and change over time. These discoveries are helping scientists learn more about how the heart develops, how it stays healthy, and what goes wrong in heart diseases. This knowledge could lead to better treatments and new ways to diagnose heart conditions, helping people live longer, healthier lives. By directly measuring multiple molecular features in hundreds to millions of single cells, single-cell techniques allow for comprehensive characterization of the diversity of cells in the heart. These single-cell transcriptome and multi-omic studies are transforming our understanding of heart development and disease. Compared with single-dimensional inspections, the combination of transcriptomes with spatial dimensions and other omics can provide a comprehensive understanding of single-cell functions, microenvironment, dynamic processes, and their interrelationships. In this review, we will introduce the latest advances in cardiac health and disease at single-cell resolution; single-cell detection methods that can be used for transcriptome, genome, epigenome, and proteome analysis; single-cell multi-omics; as well as their future application prospects. [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]

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]

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]

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]

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]

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]

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]