Characteristics of erythrocyte-derived microvesicles and its relation with atherosclerosis

Biological functions and biomedical applications of extracellular vesicles derived from blood cells

There is a growing interest in using extracellular vesicles (EVs) for therapeutic applications. EVs are composed of cytoplasmic proteins and nucleic acids and an external lipid bilayer containing transmembrane proteins on their surfaces. EVs can alter the state of the target cells by interacting with the receptor ligand of the target cell or by being internalised by the target cell. Blood cells are the primary source of EVs, and 1 μL of plasma contains approximately 1.5 × 107 EVs. Owing to their easy acquisition and the avoidance of cell amplification in vitro, using blood cells as a source of therapeutic EVs has promising clinical application prospects. This review summarises the characteristics and biological functions of EVs derived from different blood cell types (platelets, erythrocytes, and leukocytes) and analyses the prospects and challenges of using them for clinical therapeutic applications. In summary, blood cell-derived EVs can regulate different cell types such as immune cells (macrophages, T cells, and dendritic cells), stem cells, and somatic cells, and play a role in intercellular communication, immune regulation, and cell proliferation. Overall, blood cell-derived EVs have the potential for use in vascular diseases, inflammatory diseases, degenerative diseases, and injuries. To promote the clinical translation of blood cell-derived EVs, researchers need to perform further studies on EVs in terms of scalable and reproducible isolation technology, quality control, safety, stability and storage, regulatory issues, cost-effectiveness, and long-term efficacy.

Targeted therapy using engineered extracellular vesicles: principles and strategies for membrane modification

Extracellular vesicles (EVs) are 30-150 nm membrane-bound vesicles naturally secreted by cells and play important roles in intercellular communication by delivering regulatory molecules such as proteins, lipids, nucleic acids and metabolites to recipient cells. As natural nano-carriers, EVs possess desirable properties such as high biocompatibility, biological barrier permeability, low toxicity, and low immunogenicity, making them potential therapeutic delivery vehicles. EVs derived from specific cells have inherent targeting capacity towards specific cell types, which is yet not satisfactory enough for targeted therapy development and needs to be improved. Surface modifications endow EVs with targeting abilities, significantly improving their therapeutic efficiency. Herein, we first briefly introduce the biogenesis, composition, uptake and function of EVs, and review the cargo loading approaches for EVs. Then, we summarize the recent advances in surface engineering strategies of EVs, focusing on the applications of engineered EVs for targeted therapy. Altogether, EVs hold great promise for targeted delivery of various cargos, and targeted modifications show promising effects on multiple diseases.

Plasmodium falciparum infection reshapes the human microRNA profiles of red blood cells and their extracellular vesicles

Plasmodium falciparum, a human malaria parasite, develops in red blood cells (RBCs), which represent approximately 70% of all human blood cells. Additionally, RBC-derived extracellular vesicles (RBC-EVs) represent 7.3% of the total EV population. The roles of microRNAs (miRNAs) in the consequences of P. falciparum infection are unclear. Here, we analyzed the miRNA profiles of non-infected human RBCs (niRBCs), ring-infected RBCs (riRBCs), and trophozoite-infected RBCs (trRBCs), as well as those of EVs secreted from these cells. Hsa-miR-451a was the most abundant miRNA in all RBC and RBC-EV populations, but its expression level was not affected by P. falciparum infection. Overall, the miRNA profiles of RBCs and their EVs were altered significantly after infection. Most of the differentially expressed miRNAs were shared between RBCs and their EVs. A target prediction analysis of the miRNAs revealed the possible identity of the genes targeted by these miRNAs (CXCL10, OAS1, IL7, and CCL5) involved in immunomodulation.

The Role of Cell Derived Microparticles in Cardiovascular Diseases: Current Concepts

Abstract:

Cardiovascular disease remains the main cause of human morbidity and mortality in the developed countries. Microparticles (MPs) are small vesicles originating from the cell membrane as a result of various stimuli and particularly of biological processes that constitute the pathophysiology of atherosclerosis, such as endothelial damage. They form vesicles that can transfer various molecules and signals to remote target cells without direct cell to cell interaction. Circulating microparticles have been associated with cardiovascular diseases. Therefore, many studies have been designed to further investigate the role of microparticles as biomarkers for diagnosis, prognosis, and disease monitoring. To this concept the pro-thrombotic and atherogenic potential of platelets and endothelial derived MPs has gain research interest especially concerning accelerate atherosclerosis and acute coronary syndrome triggering and prognosis. MPs especially of endothelial origin have been investigated in different clinical scenarios of heart failure and in association of left ventricular loading conditions. Finally, most cardiovascular risk factors present unique patterns of circulating MPs population, highlighting their pathophysiologic link to cardiovascular disease progression. In this review article we present a synopsis of the biogenesis and characteristics of microparticles, as well as the most recent data concerning their implication in the cardiovascular settings.

Role of Circulating Microparticles in Type 2 Diabetes Mellitus: Implications for Pathological Clotting

Type 2 diabetes mellitus (T2DM) is a multifactorial chronic metabolic disease characterized by chronic hyperglycemia due to insulin resistance and a deficiency in insulin secretion. The global diabetes pandemic relates primarily to T2DM, which is the most prevalent form of diabetes, accounting for over 90% of all cases. Chronic low-grade inflammation, triggered by numerous risk factors, and the chronic activation of the immune system are prominent features of T2DM. Here we highlight the role of blood cells (platelets, and red and white blood cells) and vascular endothelial cells as drivers of systemic inflammation in T2DM. In addition, we discuss the role of microparticles (MPs) in systemic inflammation and hypercoagulation. Although once seen as inert by-products of cell activation or destruction, MPs are now considered to be a disseminated storage pool of bioactive effectors of thrombosis, inflammation, and vascular function. They have been identified to circulate at elevated levels in the bloodstream of individuals with increased risk of atherothrombosis or cardiovascular disease, two significant hallmark conditions of T2DM. There is also general evidence that MPs activate blood cells, express proinflammatory and coagulant effects, interact directly with cell receptors, and transfer biological material. MPs are considered major players in the pathogenesis of many systemic inflammatory diseases and may be potentially useful biomarkers of disease activity and may not only be of prognostic value but may act as novel therapeutic targets.

Myocardial hypoxic stress mediates functional cardiac extracellular vesicle release

AIMS

Increased shedding of extracellular vesicles (EVs)-small, lipid bilayer-delimited particles with a role in paracrine signalling-has been associated with human pathologies, e.g. atherosclerosis, but whether this is true for cardiac diseases is unknown.

METHODS AND RESULTS

Here, we used the surface antigen CD172a as a specific marker of cardiomyocyte (CM)-derived EVs; the CM origin of CD172a+ EVs was supported by their content of cardiac-specific proteins and heart-enriched microRNAs. We found that patients with aortic stenosis, ischaemic heart disease, or cardiomyopathy had higher circulating CD172a+ cardiac EV counts than did healthy subjects. Cellular stress was a major determinant of EV release from CMs, with hypoxia increasing shedding in in vitro and in vivo experiments. At the functional level, EVs isolated from the supernatant of CMs derived from human-induced pluripotent stem cells and cultured in a hypoxic atmosphere elicited a positive inotropic response in unstressed CMs, an effect we found to be dependent on an increase in the number of EVs expressing ceramide on their surface. Of potential clinical relevance, aortic stenosis patients with the highest counts of circulating cardiac CD172a+ EVs had a more favourable prognosis for transcatheter aortic valve replacement than those with lower counts.

CONCLUSION

We identified circulating CD172a+ EVs as cardiac derived, showing their release and function and providing evidence for their prognostic potential in aortic stenosis patients.

Red Blood Cells: Tethering, Vesiculation, and Disease in Micro-Vascular Flow

The red blood cell has become implicated in the progression of a range of diseases; mechanisms by which red cells are involved appear to include the transport of inflammatory species via red cell-derived vesicles. We review this role of RBCs in diseases such as diabetes mellitus, sickle cell anemia, polycythemia vera, central retinal vein occlusion, Gaucher disease, atherosclerosis, and myeloproliferative neoplasms. We propose a possibly unifying, and novel, paradigm for the inducement of RBC vesiculation during vascular flow of red cells adhered to the vascular endothelium as well as to the red pulp of the spleen. Indeed, we review the evidence for this hypothesis that links physiological conditions favoring both vesiculation and enhanced RBC adhesion and demonstrate the veracity of this hypothesis by way of a specific example occurring in splenic flow which we argue has various renderings in a wide range of vascular flows, in particular microvascular flows. We provide a mechanistic basis for membrane loss and the formation of lysed red blood cells in the spleen that may mediate their turnover. Our detailed explanation for this example also makes clear what features of red cell deformability are involved in the vesiculation process and hence require quantification and a new form of quantitative indexing.

Circulating Extracellular Vesicles As Biomarkers and Drug Delivery Vehicles in Cardiovascular Diseases

Extracellular vesicles (EVs) are composed of a lipid bilayer containing transmembrane and soluble proteins. Subtypes of EVs include ectosomes (microparticles/microvesicles), exosomes, and apoptotic bodies that can be released by various tissues into biological fluids. EV cargo can modulate physiological and pathological processes in recipient cells through near- and long-distance intercellular communication. Recent studies have shown that origin, amount, and internal cargos (nucleic acids, proteins, and lipids) of EVs are variable under different pathological conditions, including cardiovascular diseases (CVD). The early detection and management of CVD reduce premature morbidity and mortality. Circulating EVs have attracted great interest as a potential biomarker for diagnostics and follow-up of CVD. This review highlights the role of circulating EVs as biomarkers for diagnosis, prognosis, and therapeutic follow-up of CVD, and also for drug delivery. Despite the great potential of EVs as a tool to study the pathophysiology of CVD, further studies are needed to increase the spectrum of EV-associated applications.

Red Blood Cell Count: An Unrecognized Risk Factor for Nonalcoholic Fatty Liver Disease

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is becoming a global public health challenge. A convenient NAFLD indicator will greatly facilitate risk appraisal and prevention. As a readily available and inexpensive hematological index in routine clinical examinations, red blood cells (RBCs) are gaining increasing attention in many diseases, such as metabolic syndrome, but their association with NAFLD is unknown.

METHODS

This health management cohort study included 27,112 subjects (17,383 non-NAFLD and 9,729 NAFLD) with up to 5 years of follow-up (median 2.8 years). NAFLD was diagnosed by ultrasonography. NAFLD severity was categorized as mild, moderate, or severe. The generalized estimation equation (GEE), an extension of generalized linear models that allows for analysis of repeated measurements, was used to analyze the association between RBC count and NAFLD.

RESULTS

Overall, 4,332 of 17,383 (24.9%) subjects without NAFLD at baseline developed NAFLD. Incident NAFLD risk was positively associated with RBC count. After adjustment for hemoglobin and other confounders, the risk of incident NAFLD was 21%, 32%, and 51% higher in the second, third, and fourth RBC count quartiles, respectively, than in the lowest quartile. In 1,798 of 9,476 (19.0%) subjects with NAFLD at baseline, the severity of NAFLD increased. NAFLD progression risk increased progressively as RBC count increased (P for trend < 0.001). Every one-unit (10¹² cells/L) increase in RBC count was associated with a 53% [OR 1.53 (95% CI 1.32-1.77)] increased risk for NAFLD progression.

CONCLUSIONS

Elevated RBC count was independently associated with a high risk of NAFLD incidence and progression. This finding revealed a convenient NAFLD risk indicator.

Extracellular Vesicles Derived from Intermittent Hypoxia-Treated Red Blood Cells Impair Endothelial Function Through Regulating eNOS Phosphorylation and ET-1 Expression

PURPOSE

Intermittent hypoxia (IH), a main characteristic of obstructive sleep apnea (OSA) syndrome, has been known as a dominant cause of OSA-related endothelial dysfunction and hypertension. However, the underlying mechanism still remains unclear. Extracellular vesicles (EVs), small vesicles secreted by various cells, can be absorbed by endothelial cells and then influence vascular function. The aim of this research is to clarify whether and how EVs shedding from red blood cells (RBCs) are involved in IH-induced endothelial dysfunction.

METHODS

EVs were extracted by ultracentrifugation. After the identification of property and purity, EVs from IH-exposed RBCs (IH REVs) and normoxia-exposed RBCs (NOR REVs) or from OSA and non-OSA patient RBCs were utilized to treat C57BL/6 mouse aortas or human umbilical vein endothelial cells (HUVECs) for mechanistic exploration.

RESULTS

Functional results demonstrated that REVs from OSA patients dramatically impaired endothelium-dependent relaxations (EDRs). Similarly, in vivo and ex vivo studies showed that IH REVs caused significant endothelial dysfunction compared to control group. Further results presented that IH REVs blocked endothelial nitric oxide synthase (eNOS) phosphorylation through inhibiting PI3K/Akt pathway and enhanced endothelin-1 (ET-1) expression through activating Erk1/2 pathway in endothelial cells. Meanwhile, endothelial dysfunction caused by IH REVs was reversed by Akt activator SC79 as well as Erk kinase inhibitor PD98059, suggesting that PI3K/Akt/eNOS and Erk1/2/ET-1 pathways were implicated in IH REV-induced impaired EDRs.

CONCLUSIONS

This study reveals a novel role of REVs in endothelial dysfunction under IH and dissects the relevant mechanism involved in this process, which will help to establish a comprehensive understanding of OSA or IH-related endothelial dysfunction from a new scope.

Microvesicle Formation Induced by Oxidative Stress in Human Erythrocytes

Extracellular vesicles (EVs) released by different cell types play an important role in many physiological and pathophysiological processes. In physiological conditions, red blood cell (RBC)-derived EVs compose 4–8% of all circulating EVs, and oxidative stress (OS) as a consequence of different pathophysiological conditions significantly increases the amount of circulated RBC-derived EVs. However, the mechanisms of EV formation are not yet fully defined. To analyze OS-induced EV formation and RBC transformations, we used flow cytometry to evaluate cell esterase activity, caspase-3 activity, and band 3 clustering. Band 3 clustering was additionally analyzed by confocal microscopy. Two original laser diffraction-based approaches were used for the analysis of cell deformability and band 3 activity. Hemoglobin species were characterized spectrophotometrically. We showed that cell viability in tert-Butyl hydroperoxide-induced OS directly correlated with oxidant concentration to cell count ratio, and that RBC-derived EVs contained hemoglobin oxidized to hemichrome (HbChr). OS induced caspase-3 activation and band 3 clustering in cells and EVs. Importantly, we showed that OS-induced EV formation is independent of calcium. The presented data indicated that during OS, RBCs eliminated HbChr by vesiculation in order to sacrifice the cell itself, thereby prolonging lifespan and delaying the untimely clearance of in all other respects healthy RBCs.

Liquid Biopsies: Microvesicles in Cardiovascular Disease

Significance: Circulating microvesicles (cMV) are small (0.1-1 μm) phospholipid-rich blebs released by almost all cell types, and their release increases with cell activation and injury, thus reflecting the state of the cell from which they are originated. Microvesicles (MV) are found in the bloodstream, and they affect the phenotype of recipient cells, after local or systemic circulation, by intercellular transfer of their molecular content. Recent Advances: Several studies suggest the use of cell-specific MV subpopulations as predictive biomarkers for cardiovascular diseases (CVDs) at different stages and degrees of severity. In this review, we describe the state of the art of cMV as noninvasive surrogate biomarkers of vascular injury and dysfunction correlated with poor clinical outcomes in CVD. Critical Issues: Despite the growing body of evidence supporting the importance of cMV as hallmarks of CVD and their utility as biomarkers of CVD, the specific roles of each phenotype of cMV in CVD burden and prognosis still remain to be elucidated and validated in large cohorts. In addition, the development of standardized and reproducible techniques is required to be used as biomarkers for disease progression in the clinical setting. Future Directions: A multipanel approach with specific cMV phenotypes, added to current biomarkers and scores, will undoubtedly provide unique prognostic information to stratify patients for appropriate therapy on the basis of their risk of atherothrombotic disease and will open a new research area as therapeutic targets for CVD. MV will add to the implementation of precision medicine by helping the cellular and molecular characterization of CVD patients.

Red Blood Cells as Potential Repositories of MicroRNAs in the Circulatory System

The amount of erythrocyte-derived microRNAs (miRNAs) represents the majority of miRNAs expressed in whole blood. miR-451, miR-144, and miR-486, which are abundant in red blood cells (RBCs), are involved in the process of erythropoiesis and disease occurrence. Moreover, erythrocyte-derived miRNAs have been reported to be potential biomarkers of specific diseases. However, the function and underlying mechanisms of miRNAs derived from erythrocytes remain unclear. Based on a review of previously published literature, we discuss several possible pathways by which RBC miRNAs may function and propose that RBCs may serve as repositories of miRNAs in the circulatory system and participate in the regulation of gene expression mainly via the transfer of miRNAs from erythrocyte extracellular vesicles (EVs). In the whole blood, there are still other important cell types such as leukocytes and platelets harboring functional miRNAs, and hemolysis also exists, which limit the abundance of miRNAs as disease biomarkers, and thus, miRNA studies on RBCs may be impacted. In the future, the role of RBCs in the regulation of normal physiological functions of the body and the entire circulatory system under pathological states, if any, remains to be determined.

Impact of transfusion on survival in patients with myelodysplastic syndromes: Current knowledge, new insights and transfusion clinical practice

Red Blood Cell (RBC) transfusion dependence is a prevalent consequence of anaemia in patients with lower risk Myelodysplastic Syndromes (MDS). These patients have shorter survival compared to patients responding to Erythropoiesis-stimulating agents (ESA), raising the question of potential negative effects of chronic RBC transfusions on MDS prognosis, independently of IPSS-R. Besides commonly identified complications of transfusions like iron toxicity or cardiac events, oxidative stress could be a risk factor for ineffective haematopoiesis. Recently, physicochemical changes of RBC during storage have been described. These changes called storage lesions could play a role in immunomodulation in vivo. We review the currently identified sources of potential impact on transfusion-associated effects in MDS patients and we discuss the unexplored potential role of erythrocyte-derived-extracellular vesicles. They could amplify impairment of haematopoiesis in addition to the negative intrinsic effects underlying the pathology in MDS. Thus, chronic RBC transfusions appear to potentially impact the outcome of MDS.

Increased erythrocyte- and platelet-derived microvesicles in newly diagnosed type 2 diabetes mellitus

AIM

To investigate the thrombotic microenvironment in early stages of type 2 diabetes mellitus measuring platelet-derived, endothelial-derived and erythrocyte-derived microvesicles.

METHODS

We recruited 50 newly diagnosed type 2 diabetes mellitus patients who did not receive glucose-lowering treatment except for metformin and 25 matched non-type 2 diabetes mellitus volunteers. Microvesicles were measured with flow cytometry, glycated haemoglobin with high-performance liquid chromatography and advanced glycation end products with enzyme-linked immunosorbent assay.

RESULTS

Type 2 diabetes mellitus patients showed significantly higher levels of platelet-derived microvesicles [195/μL (115-409) vs 110/μL (73-150), p = 0.001] and erythrocyte-derived microvesicles [26/μL (9-100) vs 9/μL (4-25), p = 0.007] compared to non-type 2 diabetes mellitus individuals. Platelet-derived microvesicles were positively associated with fasting blood glucose (p = 0.026) and glycated haemoglobin (p = 0.002). Erythrocyte-derived microvesicles were also positively associated with fasting blood glucose (p = 0.018) but not with glycated haemoglobin (p = 0.193). No significant association was observed between platelet-derived microvesicles (p = 0.126) or erythrocyte-derived microvesicles (p = 0.857) and advanced glycation end products. Erythrocyte-derived microvesicles predicted the presence of type 2 diabetes mellitus, independently of platelet-derived microvesicles.

CONCLUSION

In newly diagnosed type 2 diabetes mellitus, ongoing atherothrombosis is evident during the early stages as evidenced by increased microvesicles levels. Furthermore, the association with glycemic profile suggests that microvesicles represent not only a novel mechanism by which hyperglycemia amplifies thrombotic tendency in type 2 diabetes mellitus but also early markers of thrombosis highlighting the need for earlier management of hyperglycemia.

Selected CD molecules and the phagocytosis of microvesicles released from erythrocytes ex vivo

BACKGROUND AND OBJECTIVES

The accumulation of microvesicles in erythrocyte concentrates during storage or irradiation may be responsible for clinical symptoms such as inflammation, coagulation and immunization. Our aim was to determine whether any of the cluster of differentiation (CD) molecules responsible for important functions are present on microvesicles, and if their expression level is dependent on the storage period of erythrocyte concentrates.

MATERIAL AND METHODS

Erythrocyte microvesicles were isolated from 'fresh' (2^nd day) and 'old' (42^nd day) stored erythrocyte concentrates. Qualitative cytometric analysis of 0·5 µm, erythrocyte-derived, PS-exposing vesicles was performed using the annexin V-FITC, anti-CD235a-PE antibody and calibrated beads. The microvesicles were also visualized under a confocal microscope. The expression of the molecules CD235a, CD44, CD47, CD55, CD59 and of phosphatidylserine (PS) was compared using flow cytometry. Measurements of microvesicle phagocytosis by human monocytes were carried out using a flow cytometer and a confocal microscope.

RESULTS

The analysis of the microvesicles with calibration beads allowed us to identify these structures with a diameter of about 0·5 µm in the 'fresh' and 'old' samples. At day 2, the microvesicles had elevated expression levels of CD47, reduced expression levels of PS, CD55 and CD59. The phagocytosis index was higher for the microvesicles isolated from the 42-day-old erythrocyte concentrates.

CONCLUSION

This research may bring us closer to understanding the factors responsible for erythrocyte ageing and to evaluate the quality of stored red blood concentrates intended for transfusion.