Cellular signaling cross-talk between different cardiac cell populations: an insight into the role of exosomes in the heart diseases and therapy

The immunology of diabetic cardiomyopathy

Diabetic cardiomyopathy is a notable microvascular complication of diabetes, characterized primarily by myocardial fibrosis and functional abnormalities. Long-term hyperglycemia induces excessive activation and recruitment of immune cells and triggers the cascade of inflammatory responses, resulting in systemic and local cardiac inflammation. Emerging evidence highlights the significant roles of immunology in modulating the pathology of diabetic cardiomyopathy. As the primary effectors of inflammatory reactions, immune cells are consistently present in cardiac tissue and can be recruited under pathological hyperglycemia circumstances. A disproportionate favor to proinflammatory types of immune cells and the increased proinflammatory cytokine levels mediate fibroblast proliferation, phenotypic transformation, and collagen synthesis and ultimately rise to cardiac fibrosis and hypertrophy. Meanwhile, the severity of cardiac fibrosis is also strongly associated with the diverse phenotypes and phenotypic alterations of the immune cells, including macrophages, dendritic cells, mast cells, neutrophils, and natural killer cells in innate immunity and CD4+ T lymphocytes, CD8+ T lymphocytes, and B lymphocytes in adaptive immunity. In this review, we synthesized the current analysis of the critical role played by the immune system and its components in the progression of diabetic cardiomyopathy. Finally, we highlight preclinical and clinical immune targeting strategies and translational implications.

Exosomal miR-15a-5p from cardiomyocytes promotes myocardial fibrosis

The emergence of myofibroblasts is a key step in myocardial fibrosis, but the trigger for the transformation of cardiac fibroblasts into myofibroblasts remains not entirely clear. Exosomes play a key role between cardiomyocytes and cardiac fibroblasts. Here, we not only investigated the relationship between exosomes derived from angiotensin (Ang)-II-treated cardiomyocytes and cardiac fibroblasts, the underlying mechanisms were also explored. Ang-II-treated C57 male mice and mouse cardiac fibroblasts were employed for in vivo and in vitro experiments, respectively. Transmission electron microscopy nanoparticle tracking analysis, and western blot of CD9, CD63, CD81 were performed to identify exosomes; QRT-PCR was performed to detect miR-15a-5p expression; luciferase reporter assay was employed to determine the interaction between miR-15a-5p and dyrk2; western blot was performed to examine the protein levels of fibrosis markers; Counting Kit-8 was performed to determine cell viability; HE and Masson staining were performed to assess the pathological changes of myocardial tissues. MiR-15a-5p expression was found up-regulated in serum of myocardial fibrosis patients, serum and myocardial tissues of Ang-II-treated mice, and Ang-II-treated cardiomyocytes. Mechanically, exosomes from Ang-II-treated cardiomyocytes shuttled miR-15a-5p to cardiac fibroblasts, where miR-15a-5p dephosphorylated NFAT by targeting dyrk2 to promote cell viability and elevated the protein levels of α-smooth muscle actin, collagen type 1 α1 and collagen type 3 α1, thus promoting myocardial fibrosis. This study identified a novel molecular target for anti-fibrotic therapeutic interventions.

Heart-derived factors and organ cross-talk in settings of health and disease: new knowledge and clinical opportunities for multimorbidity

Cardiovascular disease affects millions of people worldwide and often presents with other conditions including metabolic, renal and neurological disorders. A variety of secreted factors from multiple organs/tissues (proteins, nucleic acids and lipids) have been implicated in facilitating organ cross-talk that may contribute to the development of multimorbidity. Secreted proteins have received the most attention, with the greatest body of research related to factors released from adipose tissue (adipokines), followed by skeletal muscle (myokines). To date, there have been fewer studies on proteins released from the heart (cardiokines) implicated with organ cross-talk. Early evidence for the secretion of cardiac-specific factors facilitating organ cross-talk came in the form of natriuretic peptides which are secreted via the classical endoplasmic reticulum-Golgi pathway. More recently, studies in cardiomyocyte-specific genetic mouse models have revealed cardiac-initiated organ cross-talk. Cardiomyocyte-specific modulation of microRNAs (miR-208a and miR-23-27-24 cluster) and proteins such as the mediator complex subunit 13 (MED13), G-protein-coupled receptor kinase 2 (GRK2), mutant α-myosin heavy-chain (αMHC), ubiquitin-like modifier-activating enzyme (ATG7), oestrogen receptor alpha (ERα) and fibroblast growth factor 21 (FGF21) have resulted in metabolic and renal phenotypes. These studies have implicated a variety of factors which can be secreted via the classical pathway or via non-classical mechanisms including the release of extracellular vesicles. Cross-talk between the heart and the brain has also been described (e.g. via miR-1 and an emerging concept, interoception: detection of internal neural signals). Here we summarize these studies taking into consideration that factors may be secreted in both settings of health and in disease.

An Acellular Platform to Drive Urinary Bladder Tissue Regeneration

Impaired bladder compliance secondary to congenital or acquired bladder dysfunction can lead to irreversible kidney damage. This is managed with surgical augmentation utilizing intestinal tissue, which can cause stone formation, infections, and malignant transformation. Co-seeded bone marrow mesenchymal stem cell (MSC)/CD34+ hematopoietic stem cell (HSPC) scaffolds (PRS) have been successful in regenerating bladder tissue. However, the acquisition of viable cells is challenging in the clinical setting. Here, the regenerative capacity of human MSC/CD34+ co-cultured total condition media (TCM) is compared to media alone in immune-competent rats augmented with PRS following partial cystectomy. Augmented bladders are instilled with media (control, n = 4) or TCM (n = 5) twice a week for 4 weeks. Regenerated tissue is analyzed for smooth muscle, urothelium, vascular, and peripheral nerve regrowth. Urodynamic (UDS) measures are performed pre- and 4 weeks post-augmentation. The results demonstrate that TCM-instilled grafts have greater muscle content, larger average urothelial widths, higher percent vascularization, and more robust neural infiltration post-augmentation. UDS demonstrates greater percent bladder recovery in the TCM group, indicating functional improvement in bladder storage capacity. This study is the first to propose the use of cell-free TCM as an alternative to traditional cell-seeded scaffolds to promote bladder tissue regeneration.

IL-37 ameliorates myocardial fibrosis by regulating mtDNA-enriched vesicle release in diabetic cardiomyopathy mice

BACKGROUND

Diabetic cardiomyopathy (DCM), a serious complication of diabetes, leads to structural and functional abnormalities of the heart and ultimately evolves to heart failure. IL-37 exerts a substantial influence on the regulation of inflammation and metabolism. Whether IL-37 is involved in DCM is unknown.

METHODS

The plasma samples were collected from healthy controls, diabetic patients and DCM patients, and the level of IL-37 and its relationship with heart function were observed. The changes in cardiac function, myocardial fibrosis and mitochondrial injury in DCM mice with or without IL-37 intervention were investigated in vivo. By an in vitro co-culture approach involving HG challenge of cardiomyocytes and fibroblasts, the interaction carried out by cardiomyocytes on fibroblast profibrotic activation was studied. Finally, the possible interactive mediator between cardiomyocytes and fibroblasts was explored, and the intervention role of IL-37 and its relevant molecular mechanisms.

RESULTS

We showed that the level of plasma IL-37 in DCM patients was upregulated compared to that in healthy controls and diabetic patients. Both recombinant IL-37 administration or inducing IL-37 expression alleviated cardiac dysfunction and myocardial fibrosis in DCM mice. Mechanically, hyperglycemia impaired mitochondria through SIRT1/AMPK/PGC1α signaling, resulting in significant cardiomyocyte apoptosis and the release of extracellular vesicles containing mtDNA. Fibroblasts then engulfed these mtDNA-enriched vesicles, thereby activating TLR9 signaling and the cGAS-STING pathway to initiate pro-fibrotic process and adverse remodeling. However, the presence of IL-37 ameliorated mitochondrial injury by preserving the activity of SIRT1-AMPK-PGC1α axis, resulting in a reduction in release of mtDNA-enriched vesicle and ultimately attenuating the progression of DCM.

CONCLUSIONS

Collectively, our study demonstrates a protective role of IL-37 in DCM, offering a promising therapeutic agent for this disease.

Stromal Cell-SLIT3/Cardiomyocyte-ROBO1 Axis Regulates Pressure Overload-Induced Cardiac Hypertrophy

BACKGROUND

Recently shown to regulate cardiac development, the secreted axon guidance molecule SLIT3 maintains its expression in the postnatal heart. Despite its known expression in the cardiovascular system after birth, SLIT3's relevance to cardiovascular function in the postnatal state remains unknown. As such, the objectives of this study were to determine the postnatal myocardial sources of SLIT3 and to evaluate its functional role in regulating the cardiac response to pressure overload stress.

METHODS

We performed in vitro studies on cardiomyocytes and myocardial tissue samples from patients and performed in vivo investigation with SLIT3 and ROBO1 (roundabout homolog 1) mutant mice undergoing transverse aortic constriction to establish the role of SLIT3-ROBO1 in adverse cardiac remodeling.

RESULTS

We first found that SLIT3 transcription was increased in myocardial tissue obtained from patients with congenital heart defects that caused ventricular pressure overload. Immunostaining of hearts from WT (wild-type) and reporter mice revealed that SLIT3 is secreted by cardiac stromal cells, namely fibroblasts and vascular mural cells, within the heart. Conditioned media from cardiac fibroblasts and vascular mural cells both stimulated cardiomyocyte hypertrophy in vitro, an effect that was partially inhibited by an anti-SLIT3 antibody. Also, the N-terminal, but not the C-terminal, fragment of SLIT3 and the forced overexpression of SLIT3 stimulated cardiomyocyte hypertrophy and the transcription of hypertrophy-related genes. We next determined that ROBO1 was the most highly expressed roundabout receptor in cardiomyocytes and that ROBO1 mediated SLIT3's hypertrophic effects in vitro. In vivo, Tcf21+ fibroblast and Tbx18+ vascular mural cell-specific knockout of SLIT3 in mice resulted in decreased left ventricular hypertrophy and cardiac fibrosis after transverse aortic constriction. Furthermore, α-MHC+ cardiomyocyte-specific deletion of ROBO1 also preserved left ventricular function and abrogated hypertrophy, but not fibrosis, after transverse aortic constriction.

CONCLUSIONS

Collectively, these results indicate a novel role for the SLIT3-ROBO1-signaling axis in regulating postnatal cardiomyocyte hypertrophy induced by pressure overload.

Exploiting nuclear-mitochondrial cross-talk in theranostics: Enhancing drug delivery and diagnostic precision

The dynamic interplay between nuclear and mitochondrial processes plays a pivotal role in cellular homeostasis and disease progression. Exploiting this nuclear-mitochondrial cross-talk has emerged as a promising avenue in the field of theranostics, offering enhanced drug delivery and diagnostic precision for a wide range of medical conditions, particularly cancer. This abstract provides a brief overview of the key concepts and recent advancements in this rapidly evolving field. Recent research has elucidated the significance of mitochondrial dysfunction in various diseases, including cancer. Mitochondria, often referred to as the "powerhouses" of the cell, not only regulate energy production but also contribute to critical processes such as apoptosis, ROS generation, and metabolic signaling. Dysregulation of these mitochondrial functions is frequently associated with disease pathogenesis. In theranostics, the targeted modulation of mitochondrial function holds great promise. Mitochondria-targeted drug delivery systems have been designed to selectively deliver therapeutic agents to these organelles, thereby mitigating mitochondrial dysfunction while minimizing off-target effects. This precise drug delivery enhances the therapeutic efficacy of anticancer drugs and reduces the risk of drug resistance. Moreover, the diagnostic potential of nuclear-mitochondrial cross-talk is being harnessed to develop novel biomarkers and imaging techniques. Mitochondrial DNA mutations and alterations in mitochondrial metabolism serve as valuable indicators of disease progression and drug responsiveness. Non-invasive imaging modalities, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), have been employed to visualize mitochondrial activity and assess therapeutic outcomes.

Pharmacoscreening, molecular dynamics, and quantum mechanics of inermin from Panax ginseng: a crucial molecule inhibiting exosomal protein target associated with coronary artery disease progression

Background

Exosomes, microvesicles, carry and release several vital molecules across cells, tissues, and organs. Epicardial adipose tissue exosomes are critical in the development and progression of coronary artery disease (CAD). It is hypothesized that exosomes may transport causative molecules from inflamed tissue and deliver to the target tissue and progress CAD. Thus, identifying and inhibiting the CAD-associated proteins that are being transported to other cells via exosomes will help slow the progression of CAD.

Methods

This study uses a systems biological approach that integrates differential gene expression in the CAD, exosomal cargo assessment, protein network construction, and functional enrichment to identify the crucial exosomal cargo protein target. Meanwhile, absorption, distribution, metabolism, and excretion (ADME) screening of Panax ginseng-derived compounds was conducted and then docked against the protein target to identify potential inhibitors and then subjected to molecular dynamics simulation (MDS) to understand the behavior of the protein-ligand complex till 100 nanoseconds. Finally, density functional theory (DFT) calculation was performed on the ligand with the highest affinity with the target.

Results

Through the systems biological approach, Mothers against decapentaplegic homolog 2 protein (SMAD2) was determined as a potential target that linked with PI3K-Akt signaling, Ubiquitin mediated proteolysis, and the focal adhesion pathway. Further, screening of 190 Panax ginseng compounds, 27 showed drug-likeness properties. Inermin, a phytochemical showed good docking with -5.02 kcal/mol and achieved stability confirmation with SMAD2 based on MDS when compared to the known CAD drugs. Additionally, DFT analysis of inermin showed high chemical activity that significantly contributes to effective target binding. Overall, our computational study suggests that inermin could act against SMAD2 and may aid in the management of CAD.

Danhong Injection Up-regulates miR-125b in Endothelial Exosomes and Attenuates Apoptosis in Post-Infarction Myocardium

OBJECTIVE

To investigate the involvement of endothelial cells (ECs)-derived exosomes in the anti-apoptotic effect of Danhong Injection (DHI) and the mechanism of DHI-induced exosomal protection against postinfarction myocardial apoptosis.

METHODS

A mouse permanent myocardial infarction (MI) model was established, followed by a 14-day daily treatment with DHI, DHI plus GW4869 (an exosomal inhibitor), or saline. Phosphate-buffered saline (PBS)-induced ECs-derived exosomes were isolated, analyzed by miRNA microarray and validated by droplet digital polymerase chain reaction (ddPCR). The exosomes induced by DHI (DHI-exo), PBS (PBS-exo), or DHI+GW4869 (GW-exo) were isolated and injected into the peri-infarct zone following MI. The protective effects of DHI and DHI-exo on MI hearts were measured by echocardiography, Masson's trichrome staining, and TUNEL apoptosis assay. The Western blotting and quantitative reverse transcription PCR (qRT-PCR) were used to evaluate the expression levels of miR-125b/p53-mediated pathway components, including miR-125b, p53, Bak, Bax, and caspase-3 activities.

RESULTS

DHI significantly improved cardiac function and reduced infarct size in MI mice (P<0.01), which was abolished by the GW4869 intervention. DHI promoted the exosomal secretion in ECs (P<0.01). According to the results of exosomal miRNA microarray assay, 30 differentially expressed miRNAs in the DHI-exo were identified (28 up-regulated miRNAs and 2 down-regulated miRNAs). Among them, DHI significantly elevated miR-125b level in DHI-exo and DHI-treated ECs, a recognized apoptotic inhibitor impeding p53 signaling (P<0.05). Remarkably, treatment with DHI and DHI-exo attenuated apoptosis, elevated miR-125b expression level, inhibited capsase-3 activity, and down-regulated the expression levels of proapoptotic effectors (p53, Bak, and Bax) in post-MI hearts, whereas these effects were blocked by GW4869 (P<0.05 or P<0.01).

CONCLUSION

DHI and DHI-induced exosomes inhibited apoptosis, promoted the miR-125b expression level, and regulated the p53 apoptotic pathway in post-infarction myocardium.

Stem Cell-Based Therapy and Cell-Free Therapy as an Alternative Approach for Cardiac Regeneration

The World Health Organization reports that cardiovascular diseases (CVDs) represent 32% of all global deaths. The ineffectiveness of conventional therapies in CVDs encourages the development of novel, minimally invasive therapeutic strategies for the healing and regeneration of damaged tissue. The self-renewal capacity, multilineage differentiation, lack of immunogenicity, and immunosuppressive properties of mesenchymal stem cells (MSCs) make them a promising option for CVDs. However, growing evidence suggests that myocardial regeneration occurs through paracrine factors and extracellular vesicle (EV) secretion, rather than through differentiation into cardiomyocytes. Research shows that stem cells secrete or surface-shed into their culture media various cytokines, chemokines, growth factors, anti-inflammatory factors, and EVs, which constitute an MSC-conditioned medium (MSC-CM) or the secretome. The use of MSC-CM enhances cardiac repair through resident heart cell differentiation, proliferation, scar mass reduction, a decrease in infarct wall thickness, and cardiac function improvement comparable to MSCs without their side effects. This review highlights the limitations and benefits of therapies based on stem cells and their secretome as an innovative treatment of CVDs.

Endothelial cell dysfunction in cardiac disease: driver or consequence?

The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.

The role of exosomes in cancer biology by shedding light on their lipid contents

Exosomes are extracellular bilayer membrane nanovesicles released by cells after the fusion of multivesicular bodies (MVBs) with the plasma membrane. One of the interesting features of exosomes is their ability to carry and transfer various molecules, including lipids, proteins, nucleic acids, and therapeutic cargoes among cells. As intercellular signaling organelles, exosomes participate in various signaling processes such as tumor growth, metastasis, angiogenesis, epithelial-to-mesenchymal transition (EMT), and cell physiology such as cell-to-cell communication. Moreover, these particles are considered good vehicles to shuttle vaccines and drugs for therapeutic applications regarding cancers and tumor cells. These bioactive vesicles are also rich in various lipid molecules such as cholesterol, sphingomyelin (SM), glycosphingolipids, and phosphatidylserine (PS). These lipids play an important role in the formation, release, and function of the exosomes and interestingly, some lipids are used as biomarkers in cancer diagnosis. This review aimed to focus on exosomes lipid content and their role in cancer biology.

Engineered small extracellular vesicle-mediated NOX4 siRNA delivery for targeted therapy of cardiac hypertrophy

Small-interfering RNA (siRNA) therapy is considered a powerful therapeutic strategy for treating cardiac hypertrophy, an important risk factor for subsequent cardiac morbidity and mortality. However, the lack of safe and efficient in vivo delivery of siRNAs is a major challenge for broadening its clinical applications. Small extracellular vesicles (sEVs) are a promising delivery system for siRNAs but have limited cell/tissue-specific targeting ability. In this study, a new generation of heart-targeting sEVs (CEVs) has been developed by conjugating cardiac-targeting peptide (CTP) to human peripheral blood-derived sEVs (PB-EVs), using a simple, rapid and scalable method based on bio-orthogonal copper-free click chemistry. The experimental results show that CEVs have typical sEVs properties and excellent heart-targeting ability. Furthermore, to treat cardiac hypertrophy, CEVs are loaded with NADPH Oxidase 4 (NOX4) siRNA (siNOX4). Consequently, CEVs@siNOX4 treatment enhances the in vitro anti-hypertrophic effects by CEVs with siRNA protection and heart-targeting ability. In addition, the intravenous injection of CEVs@siNOX4 into angiotensin II (Ang II)-treated mice significantly improves cardiac function and reduces fibrosis and cardiomyocyte cross-sectional area, with limited side effects. In conclusion, the utilization of CEVs represents an efficient strategy for heart-targeted delivery of therapeutic siRNAs and holds great promise for the treatment of cardiac hypertrophy.

Exosomes in Cardiovascular Disease: From Mechanism to Therapeutic Target

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality globally. In recent decades, clinical research has made significant advances, resulting in improved survival and recovery rates for patients with CVD. Despite this progress, there is substantial residual CVD risk and an unmet need for better treatment. The complex and multifaceted pathophysiological mechanisms underlying the development of CVD pose a challenge for researchers seeking effective therapeutic interventions. Consequently, exosomes have emerged as a new focus for CVD research because their role as intercellular communicators gives them the potential to act as noninvasive diagnostic biomarkers and therapeutic nanocarriers. In the heart and vasculature, cell types such as cardiomyocytes, endothelial cells, vascular smooth muscle, cardiac fibroblasts, inflammatory cells, and resident stem cells are involved in cardiac homeostasis via the release of exosomes. Exosomes encapsulate cell-type specific miRNAs, and this miRNA content fluctuates in response to the pathophysiological setting of the heart, indicating that the pathways affected by these differentially expressed miRNAs may be targets for new treatments. This review discusses a number of miRNAs and the evidence that supports their clinical relevance in CVD. The latest technologies in applying exosomal vesicles as cargo delivery vehicles for gene therapy, tissue regeneration, and cell repair are described.

Extracellular vesicles and Duchenne muscular dystrophy pathology: Modulators of disease progression

Duchenne muscular dystrophy (DMD) is a devastating disorder and is considered to be one of the worst forms of inherited muscular dystrophies. DMD occurs as a result of mutations in the dystrophin gene, leading to progressive muscle fiber degradation and weakness. Although DMD pathology has been studied for many years, there are aspects of disease pathogenesis and progression that have not been thoroughly explored yet. The underlying issue with this is that the development of further effective therapies becomes stalled. It is becoming more evident that extracellular vesicles (EVs) may contribute to DMD pathology. EVs are vesicles secreted by cells that exert a multitude of effects via their lipid, protein, and RNA cargo. EV cargo (especially microRNAs) is also said to be a good biomarker for identifying the status of specific pathological processes that occur in dystrophic muscle, such as fibrosis, degeneration, inflammation, adipogenic degeneration, and dilated cardiomyopathy. On the other hand, EVs are becoming more prominent vehicles for custom-engineered cargos. In this review, we will discuss the possible contribution of EVs to DMD pathology, their potential use as biomarkers, and the therapeutic efficacy of both, EV secretion inhibition and custom-engineered cargo delivery.

Cardiac remodelling - Part 1: From cells and tissues to circulating biomarkers. A review from the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology

Cardiac remodelling refers to changes in left ventricular structure and function over time, with a progressive deterioration that may lead to heart failure (HF) development (adverse remodelling) or vice versa a recovery (reverse remodelling) in response to HF treatment. Adverse remodelling predicts a worse outcome, whilst reverse remodelling predicts a better prognosis. The geometry, systolic and diastolic function and electric activity of the left ventricle are affected, as well as the left atrium and on the long term even right heart chambers. At a cellular and molecular level, remodelling involves all components of cardiac tissue: cardiomyocytes, fibroblasts, endothelial cells and leucocytes. The molecular, cellular and histological signatures of remodelling may differ according to the cause and severity of cardiac damage, and clearly to the global trend toward worsening or recovery. These processes cannot be routinely evaluated through endomyocardial biopsies, but may be reflected by circulating levels of several biomarkers. Different classes of biomarkers (e.g. proteins, non-coding RNAs, metabolites and/or epigenetic modifications) and several biomarkers of each class might inform on some aspects on HF development, progression and long-term outcomes, but most have failed to enter clinical practice. This may be due to the biological complexity of remodelling, so that no single biomarker could provide great insight on remodelling when assessed alone. Another possible reason is a still incomplete understanding of the role of biomarkers in the pathophysiology of cardiac remodelling. Such role will be investigated in the first part of this review paper on biomarkers of cardiac remodelling.

Extracellular vesicle-mediated bidirectional communication between heart and other organs

In recent years, a wealth of studies has identified various molecular species released by cardiac muscle under physiological and pathological conditions that exert local paracrine and/or remote endocrine effects. Conversely, humoral factors, principally produced by organs such as skeletal muscle, kidney, or adipose tissue, may affect the function and metabolism of normal and diseased hearts. Although this cross communication within cardiac tissue and between the heart and other organs is supported by mounting evidence, research on the role of molecular mediators carried by exosomes, microvesicles, and apoptotic bodies, collectively defined as extracellular vesicles (EVs), is at an early stage of investigation. Once released in the circulation, EVs can potentially reach any organ where they transfer their cargo of proteins, lipids, and nucleic acids that exert potent biological effects on recipient cells. Although there are a few cases where such signaling was clearly demonstrated, the results from many other studies can only be tentatively inferred based on indirect evidence obtained by infusing exogenous EVs in experimental animals or by adding them to cell cultures. This area of research is in rapid expansion and most mechanistic interpretations may change in the near future; hence, the present review on the role played by EV-carried mediators in the two-way communication between heart and skeletal muscle, kidneys, bone marrow, lungs, liver, adipose tissue, and brain is necessarily limited. Nonetheless, the available data are already unveiling new, intriguing, and ample scenarios in cardiac physiology and pathophysiology.

Fibroblast-mediated intercellular crosstalk in the healthy and diseased heart

Cardiac fibroblasts constitute a major cell population in the heart. They secrete extracellular matrix components and various other factors shaping the microenvironment of the heart. In silico analysis of intercellular communication based on single-cell RNA sequencing revealed that fibroblasts are the source of the majority of outgoing signals to other cell types. This observation suggests that fibroblasts play key roles in orchestrating cellular interactions that maintain organ homeostasis but that can also contribute to disease states. Here, we will review the current knowledge of fibroblast interactions in the healthy, diseased, and aging heart. We focus on the interactions that fibroblasts establish with other cells of the heart, specifically cardiomyocytes, endothelial cells and immune cells, and particularly those relying on paracrine, electrical, and exosomal communication modes.

Hydrogen sulfide plays a potential alternative for the treatment of metabolic disorders of diabetic cardiomyopathy

Diabetic cardiomyopathy (DCM) is a cardiovascular complication that tends to occur in patients with diabetes, obesity, or insulin resistance, with a higher late mortality rate. Sustained hyperglycemia, increased free fatty acids, or insulin resistance induces metabolic disorders in cardiac tissues and cells, leading to myocardial fibrosis, left ventricular hypertrophy, diastolic and/or systolic dysfunction, and finally develop into congestive heart failure. The close connection between all signaling pathways and the complex pathogenesis of DCM cause difficulties in finding effective targets for the treatment of DCM. It reported that hydrogen sulfide (H₂S) could regulate cell energy substrate metabolism, reduce insulin resistance, protect cardiomyocytes, and improve myocardial function by acting on related key proteins such as differentiation cluster 36 (CD36) and glucose transporter 4 (GLUT4). In this article, the relative mechanisms of H₂S in alleviating metabolic disorders of DCM were reviewed, and how H₂S can better prevent and treat DCM in clinical practice will be discussed.

Current status of myocardial restoration via the paracrine function of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs) have been studied for nearly two decades as a therapy for myocardial restoration. An emerging direction to repair myocardium is through their paracrine function, which includes the utilization of MSC-derived conditioned medium or extracellular vesicles. In this review, we go over the unique characteristics of MSCs that make it suitable for "off the shelf," cell-free regenerative therapy, current MSC-derived cell-free approaches including their advantages and disadvantages, and the known mechanisms of action of the paracrine effect of MSCs. With a summary of the clinical trials and preclinical studies of MSC-derived cell-free therapy, we classify the aforementioned mechanisms into angiogenesis, immunomodulation, extracellular matrix remodeling, antiapoptosis, and antioxidation. Particularly, we discuss on ways researchers have worked toward enhancing these desired properties to improve the therapeutic outcomes and the investigation of mechanobiology involved in MSC paracrine function. Lastly, we bring up the remaining challenges in this arising field and suggestions for future directions to improve our understanding and control over the potential of MSC paracrine function for myocardial restoration.

Proteome characterisation of extracellular vesicles isolated from heart

Cardiac intercellular communication is critical for heart function and often dysregulated in cardiovascular diseases. While cardiac extracellular vesicles (cEVs) are emerging mediators of signalling, their isolation remains a technical challenge hindering our understanding of cEV protein composition. Here, we utilised Langendorff-collagenase-based enzymatic perfusion and differential centrifugation to isolate cEVs from mouse heart (yield 3-6 μg/heart). cEVs are ∼200 nm, express classical EV markers (Cd63/81/9⁺ , Tsg101⁺ , Pdcd6ip/Alix⁺ ), and are depleted of blood (Alb/Fga/Hba) and cardiac damage markers (Mb, Tnnt2, Ldhb). Comparison with mechanically-derived EVs revealed greater detection of EV markers and decreased cardiac damage contaminants. Mass spectrometry-based proteomic profiling revealed 1721 proteins in cEVs, implicated in proteasomal and autophagic proteostasis, glycolysis, and fatty acid metabolism; essential functions often disrupted in cardiac pathologies. There was striking enrichment of 942 proteins in cEVs compared to mouse heart tissue - implicated in EV biogenesis, antioxidant activity, and lipid transport, suggesting active cargo selection and specialised function. Interestingly, cEVs contain marker proteins for cardiomyocytes, cardiac progenitors, B-cells, T-cells, macrophages, smooth muscle cells, endothelial cells, and cardiac fibroblasts, suggesting diverse cellular origin. We present a method of cEV isolation and provide insight into potential functions, enabling future studies into EV roles in cardiac physiology and disease.