Regulation of microvascularization in heart failure - an endothelial cell, non-coding RNAs and exosome liaison

Exosomal Cargo: Pro-angiogeneic, anti-inflammatory, and regenerative effects in ischemic and non-ischemic heart diseases - A comprehensive review

Heart diseases are the primary cause of mortality and morbidity worldwide which inflict a heavy social and economic burden. Among heart diseases, most deaths are due to myocardial infarction (MI) or heart attack, which occurs when a decrement in blood flow to the heart causes injury to cardiac tissue. Despite several available diagnostic, therapeutic, and prognostic approaches, heart disease remains a significant concern. Exosomes are a kind of small extracellular vesicles released by different types of cells that play a part in intercellular communication by transferring bioactive molecules important in regenerative medicine. Many studies have reported the diagnostic, therapeutic, and prognostic role of exosomes in various heart diseases. Herein, we reviewed the roles of exosomes as new emerging agents in various types of heart diseases, including ischemic heart disease, cardiomyopathy, arrhythmia, and valvular disease, focusing on pathogenesis, therapeutic, diagnostic, and prognostic roles in different areas. We have also mentioned different routes of exosome delivery to target tissues, the effects of preconditioning and modification on exosome's capability, exosome production in compliance with good manufacturing practice (GMP), and their ongoing clinical applications in various medical contexts to shed light on possible clinical translation.

Recent Advances of Using Exosomes as Diagnostic Markers and Targeting Carriers for Cardiovascular Disease

Cardiovascular diseases (CVDs) are the leading cause of human death worldwide. Exosomes act as endogenous biological vectors; they possess advantages of low immunogenicity and low safety risks, also providing tissue selectivity, including the inherent targeting the to heart. Therefore, exosomes not only have been applied as biomarkers for diagnosis and therapeutic outcome confirmation but also showed potential as drug carriers for cardiovascular targeting delivery. This review aims to summarize the progress and challenges of exosomes as novel biomarkers, especially many novel exosomal noncoding RNAs (ncRNAs), and also provides an overview of the improved targeting functions of exosomes by unique engineered approaches, the latest developed administration methods, and the therapeutic effects of exosomes used as the biocarriers of medications for cardiovascular disease treatment. Also, the possible therapeutic mechanisms and the potentials for transferring exosomes to the clinic for CVD treatment are discussed. The advances, in vivo and in vitro applications, modifications, mechanisms, and challenges summarized in this review will provide a general understanding of this promising strategy for CVD treatment.

Intercellular transfer of miR-200c-3p impairs the angiogenic capacity of cardiac endothelial cells

As mediators of intercellular communication, extracellular vesicles containing molecular cargo such as microRNAs, are secreted by cells and taken up by recipient cells to influence their cellular phenotype and function. Here, we report that cardiac stress-induced differential microRNA content, with miR-200c-3p being one of the most enriched, in cardiomyocyte-derived extracellular vesicles mediates functional crosstalk with endothelial cells. Silencing of miR-200c-3p in mice subjected to chronic increased cardiac pressure overload resulted in attenuated hypertrophy, smaller fibrotic areas, higher capillary density and preserved cardiac ejection fraction. Interestingly, we were able to maximal rescue microvascular and cardiac function with very low doses of antagomir, which specifically silences miR-200c-3p expression in the non-myocyte cells. Our results reveal vesicle transfer of miR-200c-3p from cardiomyocytes to cardiac endothelial cells, underlining the importance of cardiac intercellular communication in the pathophysiology of heart failure.

CAD increases the long noncoding RNA PUNISHER in small extracellular vesicles and regulates endothelial cell function via vesicular shuttling

Long noncoding RNAs (lncRNAs) have emerged as biomarkers and regulators of cardiovascular disease. However, the expression pattern of circulating extracellular vesicle (EV)-incorporated lncRNAs in patients with coronary artery disease (CAD) is still poorly investigated. A human lncRNA array revealed that certain EV-lncRNAs are significantly dysregulated in CAD patients. Circulating small EVs (sEVs) from patients with (n = 30) or without (n = 30) CAD were used to quantify PUNISHER (also known as AGAP2-antisense RNA 1 [AS1]), GAS5, MALAT1, and H19 RNA levels. PUNISHER (p = 0.002) and GAS5 (p = 0.02) were significantly increased in patients with CAD, compared to non-CAD patients. Fluorescent labeling and quantitative real-time PCR of sEVs demonstrated that functional PUNISHER was transported into the recipient cells. Mechanistically, the RNA-binding protein, heterogeneous nuclear ribonucleoprotein K (hnRNPK), interacts with PUNISHER, regulating its loading into sEVs. Knockdown of PUNISHER abrogated the EV-mediated effects on endothelial cell (EC) migration, proliferation, tube formation, and sprouting. Angiogenesis-related gene profiling showed that the expression of vascular endothelial growth factor A (VEGFA) RNA was significantly increased in EV recipient cells. Protein stability and RNA immunoprecipitation indicated that the PUNISHER-hnRNPK axis regulates the stability and binding of VEGFA mRNA to hnRNPK. Loss of PUNISHER in EVs abolished the EV-mediated promotion of VEGFA gene and protein expression. Intercellular transfer of EV-incorporated PUNISHER promotes a pro-angiogenic phenotype via a VEGFA-dependent mechanism.

Diffuse myocardial fibrosis: mechanisms, diagnosis and therapeutic approaches

Diffuse myocardial fibrosis resulting from the excessive deposition of collagen fibres through the entire myocardium is encountered in a number of chronic cardiac diseases. This lesion results from alterations in the regulation of fibrillary collagen turnover by fibroblasts, facilitating the excessive deposition of type I and type III collagen fibres within the myocardial interstitium and around intramyocardial vessels. The available evidence suggests that, beyond the extent of fibrous deposits, collagen composition and the physicochemical properties of the fibres are also relevant in the detrimental effects of diffuse myocardial fibrosis on cardiac function and clinical outcomes in patients with heart failure. In this regard, findings from the past 20 years suggest that various clinicopathological phenotypes of diffuse myocardial fibrosis exist in patients with heart failure. In this Review, we summarize the current knowledge on the mechanisms and detrimental consequences of diffuse myocardial fibrosis in heart failure. Furthermore, we discuss the validity and usefulness of available imaging techniques and circulating biomarkers to assess the clinicopathological variation in this lesion and to track its clinical evolution. Finally, we highlight the currently available and potential future therapeutic strategies aimed at personalizing the prevention and reversal of diffuse myocardial fibrosis in patients with heart failure.

Exosomes: Emerging Diagnostic and Therapeutic Targets in Cutaneous Diseases

Skin is the largest human organ and is continuously exposed to various exogenous and endogenous trigger factors affecting body homeostasis. A number of mechanisms, including genetic, inflammatory and autoimmune ones, have been implicated in the pathogenesis of cutaneous diseases. Recently, there has been considerable interest in the role that extracellular vesicles, particularly exosomes, play in human diseases, through their modulation of multiple signaling pathways. Exosomes are nano-sized vesicles secreted by all cell types. They function as cargo carriers shuttling proteins, nucleic acids, lipids etc., thus impacting the cell-cell communications and transfer of vital information/moieties critical for skin homeostasis and disease pathogenesis. This review summarizes the available knowledge on how exosomes affect pathogenesis of cutaneous diseases, and highlights their potential as future targets for the therapy of various skin diseases.

Non-coding RNAs in Cardiac Regeneration

Cardiovascular disease is a leading cause of death worldwide, and with the dramatically increasing numbers of heart failure patients in the next 10 years, mortality will only increase [1]. For patients with end-stage heart failure, heart transplantation is the sole option. Regrettably, the number of available donor hearts is drastically lower than the number of patients waiting for heart transplantation. Despite evidence of cardiomyocyte renewal in adult human hearts, regeneration of functional myocardium after injury can be neglected. The limited regenerative capacity due to inadequate proliferation of existing cardiomyocytes is insufficient to repopulate areas of lost myocardium [2]. As a solution, the hypothesis that adult stem cells could be employed to generate functional cardiomyocytes was proposed. One of the early studies that supported this hypothesis involved direct injection of hematopoietic c-kit-positive cells derived from bone marrow into the infarcted heart [3]. However, in sharp contrast, more recent evidence emerged demonstrating that these hematopoietic stem cells only differentiate into cells down the hematopoietic lineage rather than into cardiomyocytes [4, 5], and the focus shifted towards stem cells residing in the heart, called cardiac progenitor cells. These CPCs were extracted and injected into the myocardium to regenerate the heart [6]. In recent years, over 80 pre-clinical studies employing cardiac stem cells in vivo in large and small animals to evaluate the effect on functional parameters were systematically reviewed, identifying differences between large and small animals [7]. Despite the positive outcome of these stem cell therapies on functional parameters, c-kit-positive cardiac progenitor cells were shown to contribute minimally to the generation of functional cardiomyocytes [8, 9]. This heavily debated topic is summarized concisely by van Berlo and Molkentin [10]. Recently, single-cell sequencing and genetic lineage tracing of proliferative cells in the murine heart in both homeostatic and regenerating conditions did not yield a quiescent cardiac stem cell population or other cell types that support transdifferentiation into cardiomyocytes, nor did it support proliferation of cardiac myocytes [11, 12]. Now, the focus is shifting towards exploiting the limited regenerative capacity of the cardiomyocytes themselves, by re-activating proliferation of existing cardiomyocytes through dedifferentiation, reentry into the cell cycle, and cytokinesis. This process is the new focus of research to promote cardiac regeneration, and can be controlled on multiple levels, including cell-cycle manipulation, reprogramming, small molecules, extra-cellular matrix (ECM), proteins, and RNA regulation [13].

Identification of Novel Molecular Network Expression in Acute Myocardial Infarction

Background:

In the current study, we aimed to analyze the hypothesis that human myocardial-specific extracellular RNAs expression could be used for acute myocardial injury(AMI) diagnosis.

Methodology:

We used bioinformatics’ analysis to identify RNAs linked to ubiquitin system and specific to AMI, named, (lncRNA-RP11-175K6.1), (LOC101927740), microRNA-106b-5p (miR-106b-5p) and Anaphase, promoting complex 11 (ANapc11mRNA). We measured the serum expression of the chosen RNAs in 69 individuals with acute coronary syndromes, 31 individuals with angina pectoris without MI and non-cardiac chest pain and 31 healthy control individuals by real-time reverse-transcription PCR.

Results:

Our study revealed a significant decrease in both lncRNA-RP11-175K6.1 and ANapc11mRNA expression of in the sera samples of AMI patients compared to that of the two control groups alongside with significant upregulation of miR-106b-5p.

Conclusion:

Of note, the investigated serum RNAs decrease the false discovery rate of AMI to 3.2%.

The role of endothelial miRNAs in myocardial biology and disease

The myocardium is a highly structured pluricellular tissue which is governed by an intricate network of intercellular communication. Endothelial cells are the most abundant cell type in the myocardium and exert crucial roles in both healthy myocardium and during myocardial disease. In the last decade, microRNAs have emerged as new actors in the regulation of cellular function in almost every cell type. Here, we review recent evidence on the regulatory function of different microRNAs expressed in endothelial cells, also called endothelial microRNAs, in healthy and diseased myocardium. Endothelial microRNA emerged as modulators of angiogenesis in the myocardium, they are implicated in the paracrine role of endothelial cells in regulating cardiac contractility and homeostasis, and interfere in the crosstalk between endothelial cells and cardiomyocytes.

Cardiomyocyte-Derived Exosomes: Biological Functions and Potential Therapeutic Implications

Exosomes, which are membrane-enclosed nanovesicles released by almost all cell types, have been recognized to play important roles in mediating cell-cell communication. In recent years, the physiological and pathological effects of exosomes on cardiovascular disease have been extensively studied. Exosomes can transfer proteins, mRNAs, microRNAs, and other bioactive molecules to recipient cells to influence their biological properties. In recent years, accumulating evidence has suggested that cardiomyocyte-derived exosomes play an important role in the progression of cardiovascular disease. Here, we summarize the functional roles of cardiomyocyte-derived exosomes in cardiovascular physiology and pathology.

Exosomes as carriers transporting long non‑coding RNAs: Molecular characteristics and their function in cancer (Review)

Long non‑coding RNAs (lncRNAs) comprise a sizeable class of non‑coding RNAs with a length of over 200 base pairs. Little is known about their biological function, although over 20,000 lncRNAs have been annotated in the human genome. Through a diverse range of mechanisms, their primary function is in the regulation of the transcription of protein‑coding genes. lncRNA transcriptional activation can result from a group of nucleus‑retained and chromatin‑associated lncRNAs, which function as scaffolds in the cis/trans recruitment of transcription factors, co‑activators or chromatin remodelers, and/or promoter enhancers. Exosomes are released as extracellular vesicles and they are produced by endocytic pathways. Their synthesis is initiated by various processes including ceramide synthesis, release of intracellular Ca2+ or acid‑base balance disorders. Prior to vesicle creation, selective cargo loading occurs in the Endosomal Sorting Complex Required for Transport. Participation of endosomal sorting proteins such as tetraspanins or specific sumoylated proteins required for transport has been indicated in research. The endosomal‑sorting complex consists of four components, these induce the formation of multivesicular bodies and the induction of membrane deformation to form exosomes. Nanovesicles could be formed inside multivesicular bodies to allow transport outside the cell or digestion in lysosomes. The molecular content of exosomes is more heterogenic than its synthesis process, with different cargoes being examined inside vesicles with regard to the type or stage of cancers. This paper will review the importance of lncRNAs as crucial molecular content of exosomes, indicating its involvement in tumour suppression, pro‑tumorigenic events and the development of novel therapeutic approaches in the near future. Further studies of their mechanisms of function are essential, as well as overcoming several challenges to gain a clearer insight to the approaches for the best clinical application.

Therapeutic vascular growth in the heart

Despite tremendous efforts in preclinical research over the last decades, the clinical translation of therapeutic angiogenesis to grow stable and functional blood vessels in patients with ischemic diseases continues to prove challenging. In this mini review, we briefly present the current main approaches applied to improve pro-angiogenic therapies. Specific examples from research on therapeutic cardiac angiogenesis and arteriogenesis will be discussed, and finally some suggestions for future therapeutic developments will be presented.

The clinical impact of exosomes in cardiovascular disorders: From basic science to clinical application

Cardiovascular disease (CVD) is the major cause of death globally; therefore, there is a need for the identification of a valid biomarker that accurately predicts the risk of developing CVD, and novel therapeutic approaches for its treatment. Exosomes are very small extracellular vesicles containing protein, lipid, transcription factors, messenger RNAs, noncoding RNA, and nucleic acid contents that are important players in intercellular communication, and that act via long-range signals or cell-to-cell contact. The discovery of exosomes provides potential strategies for the diagnosis and treatment of CVD. In the current review, we have explored the potential impact of exosomes on cardiovascular physiology, and their therapeutic potential in cardiovascular disorders with an emphasis on the existing preclinical studies.