miR-106a-363 cluster in extracellular vesicles promotes endogenous myocardial repair via Notch3 pathway in ischemic heart injury

Small extracellular vesicles associated miRNA in myocardial fibrosis

Myocardial fibrosis involves the loss of cardiomyocytes, myocardial fibroblast proliferation, and a reduction in angiogenesis, ultimately leading to heart failure, Given its significant implications, it is crucial to explore novel therapies for myocardial fibrosis. Recently one emerging avenue has been the use of small extracellular vesicles (sEV)-carried miRNA. In this review, we summarize the regulatory role of sEV-carried miRNA in myocardial fibrosis. We explored not only the potential diagnostic value of circulating miRNA as biomarkers for heart disease but also the therapeutic implications of sEV-carried miRNA derived from various cellular sources and applications of modified sEV. This exploration is paramount for researchers striving to develop innovative, cell-free therapies as potential drug candidates for the management of myocardial fibrosis.

MEF2C Directly Interacts with Pre-miRNAs and Distinct RNPs to Post-Transcriptionally Regulate miR-23a-miR-27a-miR-24-2 microRNA Cluster Member Expression

Transcriptional regulation constitutes a key step in gene expression regulation. Myocyte enhancer factor 2C (MEF2C) is a transcription factor of the MADS box family involved in the early development of several cell types, including muscle cells. Over the last decade, a novel layer of complexity modulating gene regulation has emerged as non-coding RNAs have been identified, impacting both transcriptional and post-transcriptional regulation. microRNAs represent the most studied and abundantly expressed subtype of small non-coding RNAs, and their functional roles have been widely documented. On the other hand, our knowledge of the transcriptional and post-transcriptional regulatory mechanisms that drive microRNA expression is still incipient. We recently demonstrated that MEF2C is able to transactivate the long, but not short, regulatory element upstream of the miR-23a-miR-27a-miR-24-2 transcriptional start site. However, MEF2C over-expression and silencing, respectively, displayed distinct effects on each of the miR-23a-miR-27a-miR-24-2 mature cluster members without affecting pri-miRNA expression levels, thus supporting additional MEF2C-driven regulatory mechanisms. Within this study, we demonstrated a complex post-transcriptional regulatory mechanism directed by MEF2C in the regulation of miR-23a-miR-27a-miR-24-2 cluster members, distinctly involving different domains of the MEF2C transcription factor and the physical interaction with pre-miRNAs and Ksrp, HnRNPa3 and Ddx17 transcripts.

miR-590-3p Overexpression Improves the Efficacy of hiPSC-CMs for Myocardial Repair

Recent evidence demonstrates that low engraftment rates limit the efficacy of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) for cardiac repair after myocardial infarction. In this study, we attempted to overcome this limitation by enhancing the proliferative capacity of transplanted hiPSC-CMs. We found that miR-590-3p overexpression increased the proliferative capacity of hiPSC-CMs. miR-590-3p overexpression increased the number of engrafted cells and had a higher efficacy for myocardial repair than control cells. Moreover, we confirmed the safety of using miR-590-3p-overexpressing hiPSC-CMs in pig hearts. These results indicated that miR-590-3p overexpression stimulated hiPSC-CM cell cycle re-entry to induce cell proliferation and increased the therapeutic efficacy in MI.

Diagnostic and prognostic value of plasma miR-106a-5p levels in patients with acute heart failure

BACKGROUND

It is essential to find reliable biomarkers for early diagnosis and prognosis of acute heart failure (AHF) for its mitigation. Currently, increasing attention is paid to the role of microRNAs (miRNAs/miRs) as diagnostic or prognostic markers for cardiovascular diseases. Since plasma miR-106a-5p has been observed to be downregulated in AHF, its value in the diagnosis and prognostic assessment of AHF deserves further exploration. Accordingly, this study analyzed the diagnostic and prognostic value of plasma miR-106a-5p in AHF patients.

METHODS

Prospectively, this study included 127 AHF patients who met the 2021 European Society of Cardiology Guidelines and 127 control individuals. Plasma miR-106a-5p levels were determined with RT-qPCR. Spearman correlation analysis was performed to evaluate the correlation of plasma miR-106a-5p levels with NT-proBNP and hs-CRP levels in AHF patients. All AHF patients were followed up for 1 year and allocated into poor and good prognosis groups, and plasma miR-106a-5p levels were compared. The diagnostic and prognostic value of plasma miR-106a-5p for AHF was assessed with a receiver-operating characteristic curve.

RESULTS

Plasma miR-106a-5p was lowly expressed in AHF patients versus controls (0.53 ± 0.26 vs. 1.09 ± 0.46) and showed significant negative correlations with NT-proBNP and hs-CRP levels. Plasma miR-106a-5p level < 0.655 could assist in AHF diagnosis. Plasma miR-106a-5p levels were markedly lower in poor-prognosis AHF patients than in good-prognosis patients. Plasma miR-106a-5p level < 0.544 could assist in predicting poor prognosis in AHF patients.

CONCLUSION

Plasma miR-106a-5p is downregulated in AHF patients and could assist in diagnosis and poor prognosis prediction of AHF.

Unraveling the Signaling Dynamics of Small Extracellular Vesicles in Cardiac Diseases

Effective intercellular communication is essential for cellular and tissue balance maintenance and response to challenges. Cellular communication methods involve direct cell contact or the release of biological molecules to cover short and long distances. However, a recent discovery in this communication network is the involvement of extracellular vesicles that host biological contents such as proteins, nucleic acids, and lipids, influencing neighboring cells. These extracellular vesicles are found in body fluids; thus, they are considered as potential disease biomarkers. Cardiovascular diseases are significant contributors to global morbidity and mortality, encompassing conditions such as ischemic heart disease, cardiomyopathies, electrical heart diseases, and heart failure. Recent studies reveal the release of extracellular vesicles by cardiovascular cells, influencing normal cardiac function and structure. However, under pathological conditions, extracellular vesicles composition changes, contributing to the development of cardiovascular diseases. Investigating the loading of molecular cargo in these extracellular vesicles is essential for understanding their role in disease development. This review consolidates the latest insights into the role of extracellular vesicles in diagnosis and prognosis of cardiovascular diseases, exploring the potential applications of extracellular vesicles in personalized therapies, shedding light on the evolving landscape of cardiovascular medicine.

Mechanisms and therapeutic strategies of extracellular vesicles in cardiovascular diseases

Cardiovascular disease (CVD) significantly impacts global society since it is the leading cause of death and disability worldwide, and extracellular vesicle (EV)-based therapies have been extensively investigated. EV delivery is involved in mediating the progression of CVDs and has great potential to be biomarker and therapeutic molecular carrier. Besides, EVs from stem cells and cardiac cells can effectively protect the heart from various pathologic conditions, and then serve as an alternative treatment for CVDs. Moreover, the research of using EVs as delivery carriers of therapeutic molecules, membrane engineering modification of EVs, or combining EVs with biomaterials further improves the application potential of EVs in clinical treatment. However, currently there are only a few articles summarizing the application of EVs in CVDs. This review provides an overview of the role of EVs in the pathogenesis and diagnosis of CVDs. It also focuses on how EVs promote the repair of myocardial injury and therapeutic methods of CVDs. In conclusion, it is of great significance to review the research on the application of EVs in the treatment of CVDs, which lays a foundation for further exploration of the role of EVs, and clarifies the prospect of EVs in the treatment of myocardial injury.

CircMap4k2 Reactivated by Aneurysm Plication Alleviates Residual Cardiac Remodeling After SVR by Enhancing Cardiomyocyte Proliferation in Post-MI Mice

INTRODUCTION

Surgical ventricular reconstruction (SVR) is an alternative therapeutic approach in patients with refractory heart failure (HF), but residual remodeling after SVR limits the improvement of HF. Recently, we reported that SVR may act as an environmental cue to reactivate endogenous proliferation of cardiomyocytes; however, it is unclear whether enhancing endogenous cardiomyocyte regeneration further improves HF after SVR.

OBJECTIVES

We aimed to explore whether circular RNAs (circRNAs) would involved in SVR and their mechanisms.

METHODS

Male C57BL/6 mice were subjected to myocardial infarction (MI) or sham surgery. Four weeks later, MI mice with a large ventricular aneurysm underwent SVR or a second open-chest operation only. Echocardiography and histological analysis were used to evaluate heart function, cardiac remodeling, and myocardial regeneration. Sequencing of circular RNAs, RNA immunoprecipitation, RNA pulldown, and luciferase reporter assay were used to explore the underlying mechanisms.

RESULTS

SVR markedly attenuated cardiac remodeling and induced cardiomyocyte regeneration, as evidenced by positive staining of Ki-67, phospho-histone H3 (pH3), and Aurora B in the plication zone, but significant residual remodeling still existed in comparison with the sham group. Sequencing results showed that SVR altered the expression profile of cardiac circRNAs, and circMap4k2 was identified as the most upregulated one. After characterizing circMap4k2, we noted that overexpression of circMap4k2 significantly promoted proliferation of cardiomyocytes in cultured neonatal rat cardiomyocytes and silencing of circMap4k2 significantly inhibited it; similar results were obtained in SVR-treated MI mice but not in MI mice without SVR treatment. Residual cardiac remodeling after SVR was further attenuated by circMap4k2 overexpression. CircMap4k2 bound with miR-106a-3p and inhibited cardiomyocyte proliferation by targeting a downstream effector of the antizyme inhibitor 1 (Azin1) gene.

CONCLUSIONS

CircMap4k2 acts as an environmental cue and targets the miR-106a-3p/Azin1 pathway to increase cardiac regeneration in the plication zone and attenuate residual remodeling after SVR.

Current optimized strategies for stem cell-derived extracellular vesicle/exosomes in cardiac repair

Ischemic heart diseases remain the leading cause of death globally, and stem cell-based therapy has been investigated as a potential approach for cardiac repair. Due to poor survival and engraftment in the cardiac ischemic milieu post transplantation, the predominant therapeutic effects of stem cells act via paracrine actions, by secreting extracellular vesicles (EVs) and/or other factors. Exosomes are nano-sized EVs of endosomal origin, and now viewed as a major contributor in facilitating myocardial repair and regeneration. However, EV/exosome therapy has major obstacles before entering clinical settings, such as limited production yield, unstable biological activity, poor homing efficiency, and low tissue retention. This review aims to provide an overview of the biogenesis and mechanisms of stem cell-derived EV/exosomes in the process of cardiac repair and discuss the current advancements in different optimized strategies to produce high-yield EV/exosomes with higher bioactivity, or engineer them with improved homing efficiency and therapeutic potency. In particular, we outline recent findings toward preclinical and clinical translation of EV/exosome therapy in ischemic heart diseases, and discuss the potential barriers in regard to clinical translation of EV/exosome therapy.

Pioneering therapies for post-infarction angiogenesis: Insight into molecular mechanisms and preclinical studies

Acute myocardial infarction (MI), despite significant progress in its treatment, remains a leading cause of chronic heart failure and cardiovascular events such as cardiac arrest. Promoting angiogenesis in the myocardial tissue after MI to restore blood flow in the ischemic and hypoxic tissue is considered an effective treatment strategy. The repair of the myocardial tissue post-MI involves a robust angiogenic response, with mechanisms involved including endothelial cell proliferation and migration, capillary growth, changes in the extracellular matrix, and stabilization of pericytes for neovascularization. In this review, we provide a detailed overview of six key pathways in angiogenesis post-MI: the PI3K/Akt/mTOR signaling pathway, the Notch signaling pathway, the Wnt/β-catenin signaling pathway, the Hippo signaling pathway, the Sonic Hedgehog signaling pathway, and the JAK/STAT signaling pathway. We also discuss novel therapeutic approaches targeting these pathways, including drug therapy, gene therapy, protein therapy, cell therapy, and extracellular vesicle therapy. A comprehensive understanding of these key pathways and their targeted therapies will aid in our understanding of the pathological and physiological mechanisms of angiogenesis after MI and the development and application of new treatment strategies.

miRNAs Epigenetic Tuning of Wall Remodeling in the Early Phase after Myocardial Infarction: A Novel Epidrug Approach

Myocardial infarction (MI) is one of the leading causes of death in Western countries. An early diagnosis decreases subsequent severe complications such as wall remodeling or heart failure and improves treatments and interventions. Novel therapeutic targets have been recognized and, together with the development of direct and indirect epidrugs, the role of non-coding RNAs (ncRNAs) yields great expectancy. ncRNAs are a group of RNAs not translated into a product and, among them, microRNAs (miRNAs) are the most investigated subgroup since they are involved in several pathological processes related to MI and post-MI phases such as inflammation, apoptosis, angiogenesis, and fibrosis. These processes and pathways are finely tuned by miRNAs via complex mechanisms. We are at the beginning of the investigation and the main paths are still underexplored. In this review, we provide a comprehensive discussion of the recent findings on epigenetic changes involved in the first phases after MI as well as on the role of the several miRNAs. We focused on miRNAs function and on their relationship with key molecules and cells involved in healing processes after an ischemic accident, while also giving insight into the discrepancy between males and females in the prognosis of cardiovascular diseases.

Overview of miR-106a Regulatory Roles: from Cancer to Aging

MicroRNAs (miRNAs) comprise a class of non-coding RNA with extensive regulatory functions within cells. MiR-106a is recognized for its super-regulatory roles in vital processes. Hence, the analysis of its expression in association with diseases has attracted considerable attention for molecular diagnosis and drug development. Numerous studies have investigated miR-106 target genes and shown that this miRNA regulates the expression of some critical cell cycle and apoptosis factors, suggesting miR-106a as an ideal diagnostic and prognostic biomarker with therapeutic potential. Furthermore, the reported correlation between miR-106a expression level and cancer drug resistance has demonstrated the complexity of its functions within different tissues. In this study, we have conducted a comprehensive review on the expression levels of miR-106a in various cancers and other diseases, emphasizing its target genes. The promising findings surrounding miR-106a suggest its potential as a valuable biomolecule. However, further validation assessments and overcoming existing limitations are crucial steps before its clinical implementation can be realized.

Extracellular vesicles: emerging roles, biomarkers and therapeutic strategies in fibrotic diseases

Extracellular vesicles (EVs), a cluster of cell-secreted lipid bilayer nanoscale particles, universally exist in body fluids, as well as cell and tissue culture supernatants. Over the past years, increasing attention have been paid to the important role of EVs as effective intercellular communicators in fibrotic diseases. Notably, EV cargos, including proteins, lipids, nucleic acids, and metabolites, are reported to be disease-specific and can even contribute to fibrosis pathology. Thus, EVs are considered as effective biomarkers for disease diagnosis and prognosis. Emerging evidence shows that EVs derived from stem/progenitor cells have great prospects for cell-free therapy in various preclinical models of fibrotic diseases and engineered EVs can improve the targeting and effectiveness of their treatment. In this review, we will focus on the biological functions and mechanisms of EVs in the fibrotic diseases, as well as their potential as novel biomarkers and therapeutic strategies.

Small Extracellular Vesicles Derived from Induced Pluripotent Stem Cells in the Treatment of Myocardial Injury

Induced pluripotent stem cell (iPSC) therapy brings great hope to the treatment of myocardial injuries, while extracellular vesicles may be one of the main mechanisms of its action. iPSC-derived small extracellular vesicles (iPSCs-sEVs) can carry genetic and proteinaceous substances and mediate the interaction between iPSCs and target cells. In recent years, more and more studies have focused on the therapeutic effect of iPSCs-sEVs in myocardial injury. IPSCs-sEVs may be a new cell-free-based treatment for myocardial injury, including myocardial infarction, myocardial ischemia-reperfusion injury, coronary heart disease, and heart failure. In the current research on myocardial injury, the extraction of sEVs from mesenchymal stem cells induced by iPSCs was widely used. Isolation methods of iPSCs-sEVs for the treatment of myocardial injury include ultracentrifugation, isodensity gradient centrifugation, and size exclusion chromatography. Tail vein injection and intraductal administration are the most widely used routes of iPSCs-sEV administration. The characteristics of sEVs derived from iPSCs which were induced from different species and organs, including fibroblasts and bone marrow, were further compared. In addition, the beneficial genes of iPSC can be regulated through CRISPR/Cas9 to change the composition of sEVs and improve the abundance and expression diversity of them. This review focused on the strategies and mechanisms of iPSCs-sEVs in the treatment of myocardial injury, which provides a reference for future research and the application of iPSCs-sEVs.

IncRNA XIST Promotes Cardiac Fibrosis in Mice with Diabetic Nephropathy via Sponging miR-106a-5p to Target RUNX1

Diabetic nephropathy (DN) accompanied by cardiac fibrosis (CF) increases the mortality rate among people with diabetes. This study sought to explore the molecular mechanism of long non-coding RNA X inactive specific transcript (lncRNA XIST) in CF in DN mice. The animal model of DN was established by streptozocin (STZ). The levels of lncRNA XIST, microRNA (miR)-106a-5p, and RUNX family transcription factor 1 (RUNX1) were determined by quantitative real-time polymerase chain reaction (qRT-PCR), followed by biochemical analysis, hematoxylin & eosin and Masson staining, echocardiography, and quantification of collagen I, collagen III, α-smooth muscle actin (α-SMA), and transforming growth factor-β1 (TGF-β1) levels through qRT-PCR and Western blot assay. The subcellular localization of lncRNA XIST was analyzed by nuclear/cytoplasmic fractionation assay and the bindings of miR-106a-5p to lncRNA XIST and RUNX1 were confirmed by RNA immunoprecipitation and dual-luciferase assays. Functional rescue experiments were performed to validate the role of miR-106a-5p/RUNX1 in CF in DN mice. lncRNA XIST and RUNX1 were elevated while miR-106a-5p was decreased in STZ mice. lncRNA XIST inhibition reduced myocardial injury and collagen deposition, along with decreased levels of fasting blood glucose, serum creatinine, blood urea nitrogen, and urinary microalbumin, collagen I, collagen III, α-SMA, and TGF-β1. lncRNA XIST competitively bound to miR-106a-5p to promote RUNX1 transcription. miR-106a-5p downregulation or RUXN1 upregulation reversed the protective role of lncRNA XIST inhibition in STZ mice. lncRNA XIST competitively bound to miR-106a-5p to promote RUNX1 transcription, thereby aggravating renal dysfunction and CF in DN mice.

Stem cell- derived extracellular vesicles as new tools in regenerative medicine - Immunomodulatory role and future perspectives

In the last few decades, the practical use of stem cells (SCs) in the clinic has attracted significant attention in the regenerative medicine due to the ability of these cells to proliferate and differentiate into other cell types. However, recent findings have demonstrated that the therapeutic capacity of SCs may also be mediated by their ability to secrete biologically active factors, including extracellular vesicles (EVs). Such submicron circular membrane-enveloped vesicles may be released from the cell surface and harbour bioactive cargo in the form of proteins, lipids, mRNA, miRNA, and other regulatory factors. Notably, growing evidence has indicated that EVs may transfer their bioactive content into recipient cells and greatly modulate their functional fate. Thus, they have been recently envisioned as a new class of paracrine factors in cell-to-cell communication. Importantly, EVs may modulate the activity of immune system, playing an important role in the regulation of inflammation, exhibiting broad spectrum of the immunomodulatory activity that promotes the transition from pro-inflammatory to pro-regenerative environment in the site of tissue injury. Consequently, growing interest is placed on attempts to utilize EVs in clinical applications of inflammatory-related dysfunctions as potential next-generation therapeutic factors, alternative to cell-based approaches. In this review we will discuss the current knowledge on the biological properties of SC-derived EVs, with special focus on their role in the regulation of inflammatory response. We will also address recent findings on the immunomodulatory and pro-regenerative activity of EVs in several disease models, including in vitro and in vivo preclinical, as well as clinical studies. Finally, we will highlight the current perspectives and future challenges of emerging EV-based therapeutic strategies of inflammation-related diseases treatment.

Extracellular vesicles mediate biological information delivery: A double-edged sword in cardiac remodeling after myocardial infarction

Acute myocardial infarction (AMI) is a severe ischemic disease with high morbidity and mortality worldwide. Maladaptive cardiac remodeling is a series of abnormalities in cardiac structure and function that occurs following myocardial infarction (MI). The pathophysiology of this process can be separated into two distinct phases: the initial inflammatory response, and the subsequent longer-term scar revision that includes the regression of inflammation, neovascularization, and fibrotic scar formation. Extracellular vesicles are nano-sized lipid bilayer vesicles released into the extracellular environment by eukaryotic cells, containing bioinformatic transmitters which are essential mediators of intercellular communication. EVs of different cellular origins play an essential role in cardiac remodeling after myocardial infarction. In this review, we first introduce the pathophysiology of post-infarction cardiac remodeling, as well as the biogenesis, classification, delivery, and functions of EVs. Then, we explore the dual role of these small molecule transmitters delivered by EVs in post-infarction cardiac remodeling, including the double-edged sword of pro-and anti-inflammation, and pro-and anti-fibrosis, which is significant for post-infarction cardiac repair. Finally, we discuss the pharmacological and engineered targeting of EVs for promoting heart repair after MI, thus revealing the potential value of targeted modulation of EVs and its use as a drug delivery vehicle in the therapeutic process of post-infarction cardiac remodeling.

From novel discovery tools and biomarkers to precision medicine-basic cardiovascular science highlights of 2021/22

Here, we review the highlights of cardiovascular basic science published in 2021 and early 2022 on behalf of the European Society of Cardiology Council for Basic Cardiovascular Science. We begin with non-coding RNAs which have emerged as central regulators cardiovascular biology, and then discuss how technological developments in single-cell 'omics are providing new insights into cardiovascular development, inflammation, and disease. We also review recent discoveries on the biology of extracellular vesicles in driving either protective or pathogenic responses. The Nobel Prize in Physiology or Medicine 2021 recognized the importance of the molecular basis of mechanosensing and here we review breakthroughs in cardiovascular sensing of mechanical force. We also summarize discoveries in the field of atherosclerosis including the role of clonal haematopoiesis of indeterminate potential, and new mechanisms of crosstalk between hyperglycaemia, lipid mediators, and inflammation. The past 12 months also witnessed major advances in the field of cardiac arrhythmia including new mechanisms of fibrillation. We also focus on inducible pluripotent stem cell technology which has demonstrated disease causality for several genetic polymorphisms in long-QT syndrome and aortic valve disease, paving the way for personalized medicine approaches. Finally, the cardiovascular community has continued to better understand COVID-19 with significant advancement in our knowledge of cardiovascular tropism, molecular markers, the mechanism of vaccine-induced thrombotic complications and new anti-viral therapies that protect the cardiovascular system.

FAIM Enhances the Efficacy of Mesenchymal Stem Cell Transplantation by Inhibiting JNK-Induced c-FLIP Ubiquitination and Degradation

Background

The poor survival rates of transplanted mesenchymal stem cells (MSCs) in harsh microenvironments impair the efficacy of MSCs transplantation in myocardial infarction (MI). Extrinsic apoptosis pathways play an important role in the apoptosis of transplanted MSCs, and Fas apoptosis inhibitory molecule (FAIM) is involved in regulation of the extrinsic apoptosis pathway. Thus, we aimed to explore whether FAIM augmentation protects MSCs against stress-induced apoptosis and thereby improves the therapeutic efficacy of MSCs.

Methods

We ligated the left anterior descending coronary artery (LAD) in the mouse heart to generate an MI model and then injected FAIM-overexpressing MSCs (MSCs_FAIM) into the peri-infarction area in vivo. Moreover, FAIM-overexpressing MSCs were challenged with oxygen, serum, and glucose deprivation (OGD) in vitro, which mimicked the harsh microenvironment that occurs in cardiac infarction.

Results

FAIM was markedly downregulated under OGD conditions, and FAIM overexpression protected MSCs against OGD-induced apoptosis. MSCs_FAIM transplantation improved cell retention, strengthened angiogenesis, and ameliorated heart function. The antiapoptotic effect of FAIM was mediated by cellular-FLICE inhibitory protein (c-FLIP), and FAIM augmentation improved the protein expression of c-FLIP by reducing ubiquitin–proteasome-dependent c-FLIP degradation. Furthermore, FAIM inhibited the activation of JNK, and treatment with the JNK inhibitor SP600125 abrogated the reduction in c-FLIP protein expression caused by FAIM silencing.

Conclusions

Overall, these results indicated that FAIM curbed the JNK-mediated, ubiquitination–proteasome-dependent degradation of c-FLIP, thereby improving the survival of transplanted MSCs and enhancing their efficacy in MI. This study may provide a novel approach to strengthen the therapeutic effect of MSC-based therapy.

Live cell screening identifies glycosides as enhancers of cardiomyocyte cell cycle activity

Promoting cardiomyocyte proliferation is a promising strategy to regenerate the heart. Yet, so far, it is poorly understood how cardiomyocyte proliferation is regulated, and no factor identified to promote mammalian cardiomyocyte proliferation has been translated into medical practice. Therefore, finding a novel factor will be vital. Here, we established a live cell screening based on mouse embryonic stem cell-derived cardiomyocytes expressing a non-functional human geminin deletion mutant fused to Azami Green (CM7/1-hgem-derived cardiomyocytes). We screened for a subset of compounds of the small molecule library Spectrum Collection and identified 19 potential inducers of stem cell-derived cardiomyocyte proliferation. Furthermore, the pro-proliferative potential of identified candidate compounds was validated in neonatal and adult rat cardiomyocytes as well as human induced pluripotent stem cell-derived cardiomyocytes. 18 of these compounds promoted mitosis and cytokinesis in neonatal rat cardiomyocytes. Among the top four candidates were two cardiac glycosides, peruvoside and convallatoxin, the flavonoid osajin, and the selective α-adrenoceptor antagonist and imidazoline I1 receptor ligand efaroxan hydrochloride. Inhibition of PTEN and GSK-3β enhanced cell cycle re-entry and progression upon stimulation with cardiac glycosides and osajin, while inhibition of IP3 receptors inhibited the cell cycle-promoting effect of cardiac glycosides. Collectively, we established a screening system and identified potential compounds to promote cardiomyocyte proliferation. Our data suggest that modulation of calcium handling and metabolism promotes cardiomyocyte proliferation, and cardiac glycosides might, besides increasing myocardial contraction force, contribute to cardiac repair by inducing cardiomyocyte proliferation.

Extracellular Vesicles: A New Frontier for Cardiac Repair

The ability of extracellular vesicles (EVs) to regulate a broad range of cellular processes has recently been used to treat diseases. Growing evidence indicates that EVs play a cardioprotective role in heart disease by activating beneficial signaling pathways. Multiple functional components of EVs and intracellular molecular mechanisms are involved in the process. To overcome the shortcomings of native EVs such as their heterogeneity and limited tropism, a series of engineering approaches has been developed to improve the therapeutic efficiency of EVs. In this review, we present an overview of the research and future directions for EVs-based cardiac therapies with an emphasis on EVs-mediated delivery of therapeutic agents. The advantages and limitations of various modification strategies are discussed, and possible opportunities for improvement are proposed. An in-depth understanding of the endogenous properties of EVs and EVs engineering strategies could lead to a promising cell-free therapy for cardiac repair.

Heterogeneous nuclear ribonucleoprotein U-actin complex derived from extracellular vesicles facilitates proliferation and migration of human coronary artery endothelial cells by promoting RNA polymerase II transcription

Coronary artery disease (CAD) represents a fatal public threat. The involvement of extracellular vesicles (EVs) in CAD has been documented. This study explored the regulation of embryonic stem cells (ESCs)-derived EVs-hnRNPU-actin complex in human coronary artery endothelial cell (HCAEC) growth. Firstly, in vitro HCAEC hypoxia models were established. EVs were extracted from ESCs by ultracentrifugation. HCAECs were treated with EVs and si-VEGF for 24 h under hypoxia, followed by assessment of cell proliferation, apoptosis, migration, and tube formation. Uptake of EVs by HCAECs was testified. Additionally, hnRNPU, VEGF, and RNA Pol II levels were determined using Western blotting and CHIP assays. Interaction between hnRNPU and actin was evaluated by Co-immunoprecipitation assay. HCAEC viability and proliferation were lowered, apoptosis was enhanced, wound fusion was decreased, and the number of tubular capillary structures was reduced under hypoxia, whereas ESC-EVs treatment counteracted these effects. Moreover, EVs transferred hnRNPU into HCAECs. EVs-hnRNPU-actin complex increased RNA Pol II level on the VEGF gene promoter and promoted VEGF expression in HCAECs. Inhibition of hnRNPU or VEGF both annulled the promotion of EVs on HCAEC growth. Collectively, ESC-EVs-hnRNPU-actin increased RNA Pol II phosphorylation and VEGF expression, thus promoting HCAEC growth.

Bioactivity and miRNome Profiling of Native Extracellular Vesicles in Human Induced Pluripotent Stem Cell-Cardiomyocyte Differentiation

Extracellular vesicles (EV) are an attractive therapy to boost cardiac regeneration. Nevertheless, identification of native EV and corresponding cell platform(s) suitable for therapeutic application, is still a challenge. Here, EV are isolated from key stages of the human induced pluripotent stem cell-cardiomyocyte (hiPSC-CM) differentiation and maturation, i.e., from hiPSC (hiPSC-EV), cardiac progenitors, immature and mature cardiomyocytes, with the aim of identifying a promising cell biofactory for EV production, and pinpoint the genetic signatures of bioactive EV. EV secreted by hiPSC and cardiac derivatives show a typical size distribution profile and the expression of specific EV markers. Bioactivity assays show increased tube formation and migration in HUVEC treated with hiPSC-EV compared to EV from committed cell populations. hiPSC-EV also significantly increase cell cycle activity of hiPSC-CM. Global miRNA expression profiles, obtained by small RNA-seq analysis, corroborate an EV-miRNA pattern indicative of stem cell to cardiomyocyte specification, confirming that hiPSC-EV are enriched in pluripotency-associated miRNA with higher in vitro pro-angiogenic and pro-proliferative properties. In particular, a stemness maintenance miRNA cluster upregulated in hiPSC-EV targets the PTEN/PI3K/AKT pathway, involved in cell proliferation and survival. Overall, the findings validate hiPSC as cell biofactories for EV production for cardiac regenerative applications.

Extracellular vesicle-packaged mitochondrial disturbing miRNA exacerbates cardiac injury during acute myocardial infarction

Mounting evidence suggests that extracellular vesicles (EVs) are effective communicators in biological signalling in cardiac physiology and pathology. However, the role of EVs in cardiac injury, particularly in ischemic myocardial scenarios, has not been fully elucidated. Here, we report that acute myocardial infarction (AMI)‐induced EVs can impair cardiomyocyte survival and exacerbate cardiac injury. EV‐encapsulated miR‐503, which is enriched during the early phase of AMI, is a critical molecule that mediates myocardial injury. Functional studies revealed that miR‐503 promoted cardiomyocyte death by directly binding to peroxisome proliferator‐activated receptor gamma coactivator‐1β (PGC‐1β) and a mitochondrial deacetylase, sirtuin 3 (SIRT3), thereby triggering mitochondrial metabolic dysfunction and cardiomyocyte death. Mechanistically, we identified endothelial cells as the primary source of miR‐503 in EVs after AMI. Hypoxia induced rapid H3K4 methylation of the promoter of the methyltransferase‐like 3 gene (METTL3) and resulted in its overexpression. METTL3 overexpression evokes N6‐methyladenosine (m⁶A)‐dependent miR‐503 biogenesis in endothelial cells. In summary, this study highlights a novel endogenous mechanism wherein EVs aggravate myocardial injury during the onset of AMI via endothelial cell‐secreted miR‐503 shuttling.

Plant-RNA in Extracellular Vesicles: The Secret of Cross-Kingdom Communication

The release of extracellular vesicles (EVs) is a common language, used by living organisms from different kingdoms as a means of communication between them. Extracellular vesicles are lipoproteic particles that contain many biomolecules, such as proteins, nucleic acids, and lipids. The primary role of EVs is to convey information to the recipient cells, affecting their function. Plant-derived extracellular vesicles (PDEVs) can be isolated from several plant species, and the study of their biological properties is becoming an essential starting point to study cross-kingdom communication, especially between plants and mammalians. Furthermore, the presence of microRNAs (miRNAs) in PDEVs represents an interesting aspect for understanding how PDEVs can target the mammalian genes involved in pathological conditions such as cancer, inflammation, and oxidative stress. In particular, this review focuses on the history of PDEVs, from their discovery, to purification from various matrices, and on the functional role of PDEV-RNAs in cross-kingdom interactions. It is worth noting that miRNAs packaged in PDEVs can be key modulators of human gene expression, representing potential therapeutic agents.

Signaling pathways and targeted therapy for myocardial infarction

Although the treatment of myocardial infarction (MI) has improved considerably, it is still a worldwide disease with high morbidity and high mortality. Whilst there is still a long way to go for discovering ideal treatments, therapeutic strategies committed to cardioprotection and cardiac repair following cardiac ischemia are emerging. Evidence of pathological characteristics in MI illustrates cell signaling pathways that participate in the survival, proliferation, apoptosis, autophagy of cardiomyocytes, endothelial cells, fibroblasts, monocytes, and stem cells. These signaling pathways include the key players in inflammation response, e.g., NLRP3/caspase-1 and TLR4/MyD88/NF-κB; the crucial mediators in oxidative stress and apoptosis, for instance, Notch, Hippo/YAP, RhoA/ROCK, Nrf2/HO-1, and Sonic hedgehog; the controller of myocardial fibrosis such as TGF-β/SMADs and Wnt/β-catenin; and the main regulator of angiogenesis, PI3K/Akt, MAPK, JAK/STAT, Sonic hedgehog, etc. Since signaling pathways play an important role in administering the process of MI, aiming at targeting these aberrant signaling pathways and improving the pathological manifestations in MI is indispensable and promising. Hence, drug therapy, gene therapy, protein therapy, cell therapy, and exosome therapy have been emerging and are known as novel therapies. In this review, we summarize the therapeutic strategies for MI by regulating these associated pathways, which contribute to inhibiting cardiomyocytes death, attenuating inflammation, enhancing angiogenesis, etc. so as to repair and re-functionalize damaged hearts.

The Regulation Mechanisms and Clinical Application of MicroRNAs in Myocardial Infarction: A Review of the Recent 5 Years

Myocardial infarction (MI) is the most frequent end-point of cardiovascular pathology, leading to higher mortality worldwide. Due to the particularity of the heart tissue, patients who experience ischemic infarction of the heart, still suffered irreversible damage to the heart even if the vascular reflow by treatment, and severe ones can lead to heart failure or even death. In recent years, several studies have shown that microRNAs (miRNAs), playing a regulatory role in damaged hearts, bring light for patients to alleviate MI. In this review, we summarized the effect of miRNAs on MI with some mechanisms, such as apoptosis, autophagy, proliferation, inflammatory; the regulation of miRNAs on cardiac structural changes after MI, including angiogenesis, myocardial remodeling, fibrosis; the application of miRNAs in stem cell therapy and clinical diagnosis; other non-coding RNAs related to miRNAs in MI during the past 5 years.

Stem Cell and Exosome Therapy in Pulmonary Hypertension

Pulmonary hypertension (PH) is a disease that eventually causes right heart failure by remodeling pulmonary blood vessels. Based on the histopathological characteristics, PH is categorized into five subgroups. Rarely, a severe clinical entity is pulmonary arterial hypertension (PAH), subgroup 1. This disease process results in pulmonary vascular alterations through dysfunction of the pulmonary endothelium and disturbance of immune responses. Although medical treatments based on these pathophysiologic concepts have been applied for more than 30 years, PAH still cannot be cured. This review addresses the feasibility of and perspectives on stem cell therapy, including the role of exosomes in PAH.

Pulmonary hypertension is a rare and progressive illness with a devastating prognosis. Promising research efforts have advanced the understanding and recognition of the pathobiology of pulmonary hypertension. Despite remarkable achievements in terms of improving the survival rate, reducing disease progression, and enhancing quality of life, pulmonary arterial hypertension (PAH) is not completely curable. Therefore, an effective treatment strategy is still needed. Recently, many studies of the underlying molecular mechanisms and technological developments have led to new approaches and paradigms for PAH treatment. Management based on stem cells and related paracrine effects, epigenetic drugs and gene therapies has yielded prospective results for PAH treatment in preclinical research. Further trials are ongoing to optimize these important insights into clinical circumstances.

Extracellular vesicles fail to trigger the generation of new cardiomyocytes in chronically infarcted hearts

Background: Extracellular vesicles (EV) mediate the therapeutic effects of stem cells but it is unclear whether this involves cardiac regeneration mediated by endogenous cardiomyocyte proliferation. Methods: Bi-transgenic MerCreMer/ZEG (n = 15/group) and Mosaic Analysis With Double Markers (MADM; n = 6/group) mouse models underwent permanent coronary artery ligation and received, 3 weeks later, 10 billion EV (from human iPS-derived cardiovascular progenitor cells [CPC]), or saline, injected percutaneously under echo guidance in the peri-infarcted myocardium. Endogenous cardiomyocyte proliferation was tracked by EdU labeling and biphoton microscopy. Other end points, including cardiac function (echocardiography and MRI), histology and transcriptomics were blindly assessed 4-6 weeks after injections. Results: There was no proliferation of cardiomyocytes in either transgenic mouse strains. Nevertheless, EV improved cardiac function in both models. In MerCreMer/ZEG mice, LVEF increased by 18.3 ± 0.2% between baseline and the end-study time point in EV-treated hearts which contrasted with a decrease by 2.3 ± 0.2% in the PBS group; MADM mice featured a similar pattern as intra-myocardial administration of EV improved LVEF by 13.3 ± 0.16% from baseline whereas it decreased by 14.4 ± 0.16% in the control PBS-injected group. This functional improvement was confirmed by MRI and associated with a reduction in infarct size, the decreased expression of several pro-fibrotic genes and an overexpression of the anti-fibrotic miRNA 133-a1 compared to controls. Experiments with an anti-miR133-a demonstrated that the cardio-reparative effects of EV were partly abrogated. Conclusions: EV-CPC do not trigger cardiomyocyte proliferation but still improve cardiac function by other mechanisms which may include the regulation of fibrosis.

Extracellular vesicles in cardiovascular disease: Biological functions and therapeutic implications

Extracellular vesicles (EVs), including exosomes and microvesicles, are lipid bilayer particles naturally released from the cell. While exosomes are formed as intraluminal vesicles (ILVs) of the multivesicular endosomes (MVEs) and released to extracellular space upon MVE-plasma membrane fusion, microvesicles are generated through direct outward budding of the plasma membrane. Exosomes and microvesicles have same membrane orientation, different yet overlapping sizes; their cargo contents are selectively packed and dependent on the source cell type and functional state. Both exosomes and microvesicles can transfer bioactive RNAs, proteins, lipids, and metabolites from donor to recipient cells and influence the biological properties of the latter. Over the last decade, their potential roles as effective inter-tissue communicators in cardiovascular physiology and pathology have been increasingly appreciated. In addition, EVs are attractive sources of biomarkers for the diagnosis and prognosis of diseases, because they acquire their complex cargoes through cellular processes intimately linked to disease pathogenesis. Furthermore, EVs obtained from various stem/progenitor cell populations have been tested as cell-free therapy in various preclinical models of cardiovascular diseases and demonstrate unequivocally encouraging benefits. Here we summarize the findings from recent research on the biological functions of EVs in the ischemic heart disease and heart failure, and their potential as novel diagnostic biomarkers and therapeutic opportunities.

Adding a "Notch" to Cardiovascular Disease Therapeutics: A MicroRNA-Based Approach

Dysregulation of the Notch pathway is implicated in the pathophysiology of cardiovascular diseases (CVDs), but, as of today, therapies based on the re-establishing the physiological levels of Notch in the heart and vessels are not available. A possible reason is the context-dependent role of Notch in the cardiovascular system, which would require a finely tuned, cell-specific approach. MicroRNAs (miRNAs) are short functional endogenous, non-coding RNA sequences able to regulate gene expression at post-transcriptional levels influencing most, if not all, biological processes. Dysregulation of miRNAs expression is implicated in the molecular mechanisms underlying many CVDs. Notch is regulated and regulates a large number of miRNAs expressed in the cardiovascular system and, thus, targeting these miRNAs could represent an avenue to be explored to target Notch for CVDs. In this Review, we provide an overview of both established and potential, based on evidence in other pathologies, crosstalks between miRNAs and Notch in cellular processes underlying atherosclerosis, myocardial ischemia, heart failure, calcification of aortic valve, and arrhythmias. We also discuss the potential advantages, as well as the challenges, of using miRNAs for a Notch-based approach for the diagnosis and treatment of the most common CVDs.