Phospholipidomics reveals differences in glycerophosphoserine profiles of hypothermically stored red blood cells and microvesicles

Understanding exosomes: Part 1-Characterization, quantification and isolation techniques

Exosomes are the smallest subset of extracellular signaling vesicles secreted by most cells with a diameter in the range of 30-150 nm. Their use has gained great momentum recently due to their ability to be utilized as diagnostic tools with a vast array of therapeutic applications. Over 5000 publications are currently being published yearly on this topic, and this number is only expected to dramatically increase as novel therapeutic strategies continue to be investigated. This review article first focuses on understanding exosomes, including their cellular origin, biogenesis, function, and characterization. Thereafter, overviews of the quantification methods and isolation techniques are given with discussion over their potential use as novel therapeutics in regenerative medicine.

An impedance based microfluidic sensor for evaluation of individual red blood cell solute permeability

-In this paper, we investigate a microfluidic based sensing device for cell membrane permeability measurements in real time with applications in rapid assessment of red blood cell (RBC) quality at the individual cell level. The microfluidic chip was designed with unique abilities to line up the RBCs in the centerline of the microchannel using positive dielectrophoresis (p-DEP) forces, rapid mixing of RBCs with various media (e.g. containing permeating or nonpermeating solutes) injected from different inlets to achieve high mixing efficiency. The chip detects the impedance values of the RBCs within 0.19 s from the start of mixing with other media, at ten electrodes along the length of the channel and enables time series measurements of volume change of individual cell caused by cell osmosis in anisosmotic fluids over a 0.8 s postmixing timespan. This technique enables estimating water permeability of individual cell accurately. Here we first present confirmation of a linear voltage-diameter relationship in polystyrene bead standards. Next, we show that under equilibrium conditions, the voltage-volume relationship in rat red blood cells (RBCs) is linear, corresponding to previously published Boyle van 't Hoff plots. Using rat cells as a model for human, we present the first measurement of water permeability in individual red blood cells and confirm that these data align with previously published population level values for human RBC. Finally, we present preliminary evidence for possible application of our device to identify individual RBCs infected with Plasmodium falciparum malaria parasites. Future developments using this device will address the use of whole blood with non-homogenous cell populations, a task currently performed by clinical Coulter counters.

Red Blood Cell Metabolism In Vivo and In Vitro

Red blood cells (RBC) are the most abundant cell in the human body, with a central role in oxygen transport and its delivery to tissues. However, omics technologies recently revealed the unanticipated complexity of the RBC proteome and metabolome, paving the way for a reinterpretation of the mechanisms by which RBC metabolism regulates systems biology beyond oxygen transport. The new data and analytical tools also informed the dissection of the changes that RBCs undergo during refrigerated storage under blood bank conditions, a logistic necessity that makes >100 million units available for life-saving transfusions every year worldwide. In this narrative review, we summarize the last decade of advances in the field of RBC metabolism in vivo and in the blood bank in vitro, a narrative largely influenced by the authors' own journeys in this field. We hope that this review will stimulate further research in this interesting and medically important area or, at least, serve as a testament to our fascination with this simple, yet complex, cell.

Cross talk between exosomes and pancreatic β-cells in diabetes

Exosomes are a class of extracellular vesicles with a diameter of 50-100 nm secreted by various cells. They are generated through complex intracellular production mechanisms before being secreted to the extracellular environment. Due to their inclusion of proteins, lipids, and nucleic acids, exosomes play an important role in intercellular communication. Pancreatic β-cells play an irreplaceable role in the body's glucose metabolism. Their dysfunction is one of the causes of diabetes. Exosomes of various cells regulate the function of β-cells by regulating autoimmunity, delivering non-coding RNAs, or directly regulating intracellular signal pathways. This communication between β-cells and other cells plays an important role in the pathogenesis and development of diabetes, and has potential for clinical application. This paper reviews the biological sources and functions of exosomes, as well as intercellular crosstalk between β-cells and other cells that is involved in β-cell failure and regeneration.

Extracellular Vesicles and Cancer Therapy: Insights into the Role of Oxidative Stress

Oxidative stress plays a significant role in cancer development and cancer therapy, and is a major contributor to normal tissue injury. The unique characteristics of extracellular vesicles (EVs) have made them potentially useful as a diagnostic tool in that their molecular content indicates their cell of origin and their lipid membrane protects the content from enzymatic degradation. In addition to their possible use as a diagnostic tool, their role in how normal and diseased cells communicate is of high research interest. The most exciting area is the association of EVs, oxidative stress, and pathogenesis of numerous diseases. However, the relationship between oxidative stress and oxidative modifications of EVs is still unclear, which limits full understanding of the clinical potential of EVs. Here, we discuss how EVs, oxidative stress, and cancer therapy relate to one another; how oxidative stress can contribute to the generation of EVs; and how EVs’ contents reveal the presence of oxidative stress. We also point out the potential promise and limitations of using oxidatively modified EVs as biomarkers of cancer and tissue injury with a focus on pediatric oncology patients.

Exosome Processing and Characterization Approaches for Research and Technology Development

Exosomes are extracellular vesicles that share components of their parent cells and are attractive in biotechnology and biomedical research as potential disease biomarkers as well as therapeutic agents. Crucial to realizing this potential is the ability to manufacture high-quality exosomes; however, unlike biologics such as proteins, exosomes lack standardized Good Manufacturing Practices for their processing and characterization. Furthermore, there is a lack of well-characterized reference exosome materials to aid in selection of methods for exosome isolation, purification, and analysis. This review informs exosome research and technology development by comparing exosome processing and characterization methods and recommending exosome workflows. This review also provides a detailed introduction to exosomes, including their physical and chemical properties, roles in normal biological processes and in disease progression, and summarizes some of the on-going clinical trials.

Transfusion‑related immunomodulation in patients with cancer: Focus on the impact of extracellular vesicles from stored red blood cells (Review)

Red blood cell (RBC) transfusions may have a negative impact on the prognosis of patients with cancer, where transfusion‑related immunomodulation (TRIM) may be a significant contributing factor. A number of components have been indicated to be associated with TRIM. Among these, the impact of extracellular vesicles (EVs) has been garnering increasing attention from researchers. EVs are defined as nano‑scale, cell‑derived vesicles that carry a variety of bioactive molecules, including proteins, nucleic acids and lipids, to mediate cell‑to‑cell communication and exert immunoregulatory functions. RBCs in storage constitutively secrete EVs, which serve an important role in TRIM in patients with cancer receiving a blood transfusion. Therefore, the present review aimed to first summarize the available information on the biogenesis and characterization of EVs. Subsequently, the possible mechanisms of TRIM in patients with cancer and the impact of EVs on TRIM were discussed, aiming to provide an outlook for future studies, specifically for formulating recommendations for managing patients with cancer receiving RBC transfusions.

Lipid profile of extracellular vesicles and their relationship with bovine oocyte developmental competence: New players in intra follicular cell communication

Cell communication within the ovarian follicle is crucial during folliculogenesis to assure an ideal environment for the oocyte to achieve full developmental competence. Intercellular communication is facilitated by the presence of follicular fluid, which mediates the transfer of signaling molecules. Recently, extracellular vesicles (exosomes and microvesicles) containing mRNAs, miRNAs and proteins were described in mammalian follicular fluid. Besides these molecules, extracellular vesicles (EVs) can mediate the transfer of lipids that can act as signal transducers activating second messengers and modulating intracellular pathways. Our goal was to determine the lipid profile of exosomes (small extracellular vesicles) and microvesicles (large extracellular vesicles) from bovine ovarian follicles containing oocytes with different developmental capabilities to verify potential relationships to competence. Using mass spectrometry, we examined the lipid content of EVs present in the follicular fluid of follicles enclosing oocytes that were either unable to cleave (NCLEAVE), arrested at cleavage stage (CLEAVE), or developed to the blastocyst stage (BLAST) after parthenogenetic activation. Although most of the 514 lipids identified in the follicular fluid EVs were common among all groups, 10 exosome-derived lipids and 15 microvesicle-derived lipids were present exclusively in the BLAST group, suggesting a potential relationship with developmental competence. Therefore, our data indicate that the EVs present in follicular fluid of antral follicles of similar morphology contain lipids that may be used as biomarkers associated with the developmental capability of the oocyte to develop to the blastocyst stage.

Aptamer-Based Detection of Circulating Targets for Precision Medicine

The past decade has witnessed ongoing progress in precision medicine to improve human health. As an emerging diagnostic technique, liquid biopsy can provide real-time, comprehensive, dynamic physiological and pathological information in a noninvasive manner, opening a new window for precision medicine. Liquid biopsy depends on the sensitive and reliable detection of circulating targets (e.g., cells, extracellular vesicles, proteins, microRNAs) from body fluids, the performance of which is largely governed by recognition ligands. Aptamers are single-stranded functional oligonucleotides, capable of folding into unique tertiary structures to bind to their targets with superior specificity and affinity. Their mature evolution procedure, facile modification, and affinity regulation, as well as versatile structural design and engineering, make aptamers ideal recognition ligands for liquid biopsy. In this review, we present a broad overview of aptamer-based liquid biopsy techniques for precision medicine. We begin with recent advances in aptamer selection, followed by a summary of state-of-the-art strategies for multivalent aptamer assembly and aptamer interface modification. We will further describe aptamer-based micro-/nanoisolation platforms, aptamer-enabled release methods, and aptamer-assisted signal amplification and detection strategies. Finally, we present our perspectives regarding the opportunities and challenges of aptamer-based liquid biopsy for precision medicine.

Extracellular vesicles in cancer progression: are they part of the problem or part of the solution?

Extracellular vesicles (EVs) are released especially by cancer cells. They modulate the tumor microenvironment by interacting with immune cells while carrying immunosuppressive or immunostimulatory molecules. In this review, we will explore some conflicting reports regarding the immunological outcomes of EVs in cancer progression, in which they might initiate an antitumor immune response or an immunosuppressive response. Concerning immunosuppression, the role of tumor-derived EVs' in the adenosinergic system is underexplored. The enhancement of adenosine (ADO) levels in the tumor microenvironment impairs T-cell function and cytokine release. However, some tumor-derived EVs may deliver immunostimulatory factors, promoting immunogenic activity, even with ADO production. The modulatory role of ADO over the tumor progression represents a piece in an intricate microenvironment with anti and pro tumoral seesaw-like mechanisms.

Qualitative distribution of endogenous phosphatidylcholine and sphingomyelin in serum using LC-MS/MS based profiling

PCs and SMs are the major types of glycerophospholipids and sphingophospholipids, the two main categories of phospholipids (PLs). To study the qualitative distribution of serum phosphatidylcholine (PC) and sphingomyelin (SM) in human and three rodent species, liquid chromatography-Orbitrap mass spectrometry (LC-Orbitrap-MS/MS) was used to identify them comprehensively through the accurate mass measurement of both precursor ions and their corresponding product ions. Based on the fragmentation rules of standards, the product ions at m/z 184.0733 were filtered to maximally screen possible PC and SM molecules. For PC, the fatty acid at sn-1 and sn-2 of the glycerol backbone was identified based on the product ions in negative mode. A total of 91 PCs and 31 SMs molecular species, consisting of 166 PCs and 39 SMs regioisomers, were detected in human serum, which is the most comprehensive identification of PC and SM species in serum. The qualitative distributions of PC in rat and SM in golden hamster, respectively, were more similar with that of human from an overall perspective. Those results provided guidance regarding to the animal model selection for mimicking lipid related-syndromes or diseases in human.

Interplay between Endoplasmic Reticulum Stress and Large Extracellular Vesicles (Microparticles) in Endothelial Cell Dysfunction

Upon increased demand for protein synthesis, accumulation of misfolded and/or unfolded proteins within the endoplasmic reticulum (ER), a pro-survival response is activated termed unfolded protein response (UPR), aiming at restoring the proper function of the ER. Prolonged activation of the UPR leads, however, to ER stress, a cellular state that contributes to the pathogenesis of various chronic diseases including obesity and diabetes. ER stress response by itself can result in endothelial dysfunction, a hallmark of cardiovascular disease, through various cellular mechanisms including apoptosis, insulin resistance, inflammation and oxidative stress. Extracellular vesicles (EVs), particularly large EVs (lEVs) commonly referred to as microparticles (MPs), are membrane vesicles. They are considered as a fingerprint of their originating cells, carrying a variety of molecular components of their parent cells. lEVs are emerging as major contributors to endothelial cell dysfunction in various metabolic disease conditions. However, the mechanisms underpinning the role of lEVs in endothelial dysfunction are not fully elucidated. Recently, ER stress emerged as a bridging molecular link between lEVs and endothelial cell dysfunction. Therefore, in the current review, we summarized the roles of lEVs and ER stress in endothelial dysfunction and discussed the molecular crosstalk and relationship between ER stress and lEVs in endothelial dysfunction.

Spicule movement on RBCs during echinocyte formation and possible segregation in the RBC membrane

We use phase contrast microscopy of red blood cells to observe the transition between the initial discocyte shape and a spiculated echinocyte form. During the early stages of this change, spicules can move across the surface of the cell; individual spicules can also split apart into pairs. One possible explanation of this behaviour is that the membrane forms large scale domains in association with the spicules. The spicules are formed initially at the rim of the cell and then move at speeds of up to 3 μm/min towards the centre of the disc. Spicule formation that was reversed and then allowed to proceed a second time resulted in spicules at reproducible places, a shape memory effect that implies that the cytoskeleton contributes towards stopping the spicule movement. The splitting of the spicules produces a well-defined shape change with an increase in membrane curvature associated with formation of the daughter pair of spicules; the total boundary length around the spicules also increases. Following the model in which the spicules are associated with lipid domains, these observations suggest an experimental procedure that could potentially be applied to the calculation of the line tension of lipid domains in living cells.

The Role of Extracellular Vesicles in Viral Infection and Transmission

Extracellular vesicles (EVs) have been found to be released by any type of cell and can be retrieved in every circulating body fluid, namely blood (plasma, serum), saliva, milk, and urine. EVs were initially considered a cellular garbage disposal tool, but later it became evident that they are involved in intercellular signaling. There is evidence that viruses can use EV endocytic routes to enter uninfected cells and hijack the EV secretory pathway to exit infected cells, thus illustrating that EVs and viruses share common cell entry and biogenesis mechanisms. Moreover, EVs play a role in immune response against viral pathogens. EVs incorporate and spread both viral and host factors, thereby prompting or inhibiting immune responses towards them via a multiplicity of mechanisms. The involvement of EVs in immune responses, and their potential use as agents modulating viral infection, will be examined. Although further studies are needed, the engineering of EVs could package viral elements or host factors selected for their immunostimulatory properties, to be used as vaccines or tolerogenic tools in autoimmune diseases.

Alterations in phospholipid profiles of erythrocytes deep-frozen without cryoprotectants

The erythrocyte membrane is composed of a phospholipid bilayer, which is known to undergo physicochemical changes during storage at low temperatures. This study was conducted to identify marker phospholipids that indicate alteration during deep-frozen storage and to determine the amount of marker phospholipids. Our research suggested a method to detect phospholipids by profiling analysis of thermally injured red blood cells (RBCs) without protecting agents. Human blood was stored at -80°C for 72 days. The RBC membrane phospholipids were extracted through a modified Bligh and Dyer method. Six selected phospholipids were analyzed and quantified using liquid chromatography-tandem mass spectrometry, and an in vitro model system was developed. The intracellular level of N-nervonoyl-D-erythro-sphingosylphosphorylcholine significantly increased in the thermally injured RBCs, and multiple biomarker candidates were evaluated by profiling analysis and mass spectrometry technology for targeted metabolomics.

Extracellular membrane vesicles in the three domains of life and beyond

Cells from all three domains of life, Archaea, Bacteria and Eukarya, produce extracellular vesicles (EVs) which are sometimes associated with filamentous structures known as nanopods or nanotubes. The mechanisms of EV biogenesis in the three domains remain poorly understood, although studies in Bacteria and Eukarya indicate that the regulation of lipid composition plays a major role in initiating membrane curvature. EVs are increasingly recognized as important mediators of intercellular communication via transfer of a wide variety of molecular cargoes. They have been implicated in many aspects of cell physiology such as stress response, intercellular competition, lateral gene transfer (via RNA or DNA), pathogenicity and detoxification. Their role in various human pathologies and aging has aroused much interest in recent years. EVs can be used as decoys against viral attack but virus-infected cells also produce EVs that boost viral infection. Here, we review current knowledge on EVs in the three domains of life and their interactions with the viral world.

Metabolic signature of extracellular vesicles depends on the cell culture conditions

One of the greatest bottlenecks in extracellular vesicle (EV) research is the production of sufficient material in a consistent and effective way using in vitro cell models. Although the production of EVs in bioreactors maximizes EV yield in comparison to conventional cell cultures, the impact of their cell growth conditions on EVs has not yet been established. In this study, we grew two prostate cancer cell lines, PC-3 and VCaP, in conventional cell culture dishes and in two-chamber bioreactors to elucidate how the growth environment affects the EV characteristics. Specifically, we wanted to investigate the growth condition-dependent differences by non-targeted metabolite profiling using liquid chromatography-mass spectrometry (LC-MS) analysis. EVs were also characterized by their morphology, size distribution, and EV protein marker expression, and the EV yields were quantified by NTA. The use of bioreactor increased the EV yield >100 times compared to the conventional cell culture system. Regarding morphology, size distribution and surface markers, only minor differences were observed between the bioreactor-derived EVs (BR-EVs) and the EVs obtained from cells grown in conventional cell cultures (C-EVs). In contrast, metabolomic analysis revealed statistically significant differences in both polar and non-polar metabolites when the BR-EVs were compared to the C-EVs. The results show that the growth conditions markedly affected the EV metabolite profiles and that metabolomics was a sensitive tool to study molecular differences of EVs. We conclude that the cell culture conditions of EV production should be standardized and carefully detailed in publications and care should be taken when EVs from different production platforms are compared with each other for systemic effects.

Plasma Membrane Lipid Domains as Platforms for Vesicle Biogenesis and Shedding?

Extracellular vesicles (EVs) contribute to several pathophysiological processes and appear as emerging targets for disease diagnosis and therapy. However, successful translation from bench to bedside requires deeper understanding of EVs, in particular their diversity, composition, biogenesis and shedding mechanisms. In this review, we focus on plasma membrane-derived microvesicles (MVs), far less appreciated than exosomes. We integrate documented mechanisms involved in MV biogenesis and shedding, focusing on the red blood cell as a model. We then provide a perspective for the relevance of plasma membrane lipid composition and biophysical properties in microvesiculation on red blood cells but also platelets, immune and nervous cells as well as tumor cells. Although only a few data are available in this respect, most of them appear to converge to the idea that modulation of plasma membrane lipid content, transversal asymmetry and lateral heterogeneity in lipid domains may play a significant role in the vesiculation process. We suggest that lipid domains may represent platforms for inclusion/exclusion of membrane lipids and proteins into MVs and that MVs could originate from distinct domains during physiological processes and disease evolution.

Transfusion-associated adverse reactions (TAARs) and cytokine accumulations in the stored blood components: the impact of prestorage versus poststorage leukoreduction

Leukoreduction in blood units could prevent patients undergoing transfusions from transfusion-associated adverse reactions (TAARs) such as febrile nonhemolytic transfusion reactions (FNHTRs). However, the effect of prestorage and poststorage leukoreduction on TAARs and its underlying mechanisms in stored blood components remains to be determined. Therefore, we investigated the impact of prestorage leukocyte-reduced (pre-LR) and poststorage leukocyte-reduced (post-LR) blood products, including red blood cells (RBCs) and apheresis platelets (PHs), on the incidence of FNHTRs and other TAARs in patients who received transfusions from 2009 to 2014 in a tertiary care center. We also investigated the difference of leukocyte-related bioactive mediators between pre- and post-LR blood components. The results indicated that prevalence of TAARs was significantly reduced in the transfusions of pre-LR blood components. Particularly, the prevalence of FNHTRs was significantly reduced in the pre-LR RBC transfusions and the prevalence of allergy reactions was markedly reduced in the pre-LR PH transfusions. Furthermore, in vitro evaluation of cytokines in the pre- and post-LR blood components revealed that IL-1β, IL-8 and RANTES levels were significantly elevated in the post-LR RBCs during the storage. In contrast, IL-1β, IL-6 and IL-8 levels were significantly elevated in the post-LR PHs during the storage. These findings suggested that prestorage leukoreduction had a diminishing effect on the development of TAARs, which could be associated with less accumulation of cytokines in the stored blood components.

Phospholipid composition of packed red blood cells and that of extracellular vesicles show a high resemblance and stability during storage

Red blood cells (RBCs) are stored up to 35-42days at 2-6°C in blood banks. During storage, the RBC membrane is challenged by energy depletion, decreasing pH, altered cation homeostasis, and oxidative stress, leading to several biochemical and morphological changes in RBCs and to shedding of extracellular vesicles (EVs) into the storage medium. These changes are collectively known as RBC storage lesions. EVs accumulate in stored RBC concentrates and are, thus, transfused into patients. The potency of EVs as bioactive effectors is largely acknowledged, and EVs in RBC concentrates are suspected to mediate some adverse effects of transfusion. Several studies have shown accumulation of lipid raft-associated proteins in RBC EVs during storage, whereas a comprehensive phospholipidomic study on RBCs and corresponding EVs during the clinical storage period is lacking. Our mass spectrometric and chromatographic study shows that RBCs maintain their major phospholipid (PL) content well during storage despite abundant vesiculation. The phospholipidomes were largely similar between RBCs and EVs. No accumulation of raft lipids in EVs was seen, suggesting that the primary mechanism of RBC vesiculation during storage might not be raft -based. Nonetheless, a slight tendency of EV PLs for shorter acyl chains was observed.

Exosomes, not protein or lipids, in mesenteric lymph activate inflammation: Unlocking the mystery of post-shock multiple organ failure

BACKGROUND

Previous studies have shown that mesenteric lymph (ML) has a crucial role in driving the systemic inflammatory response after trauma/hemorrhagic shock (T/HS). The specific mediators in the ML that contribute to its biological activity remain unclear despite decades of study. Exosomes are extracellular vesicles that are shed into body fluids such as serum and urine that can mediate intercellular communication. We hypothesized that exosomes are present in the ML after trauma/shock and are responsible for the biological activity of ML.

METHODS

Male rats underwent cannulation of the vessels and mesenteric lymph duct. T/HS was induced by laparotomy and 60 minutes of HS (mean arterial pressure, 35 mmHg), followed by resuscitation. The ML was collected during three distinct time periods (pre-shock, shock, and resuscitation phase) and subsequently separated into exosome and supernatant fractions. Exosomes were characterized by electron microscope, nanoparticle tracking analysis, and immunoblotting. The biological activity of exosomes and supernatant of ML were characterized using a monocyte NF-κB reporter assay and by measuring macrophage intracellular TNF-α production.

RESULTS

Exosomes were identified in ML by size and expression of the exosome markers CD63 and HSP70. The number of exosomes present in the ML was 2-fold increased during shock and 4-fold decreased in resuscitation phase compared to pre-shock. However, biological activity of exosomes isolated during the resuscitation phase was markedly increased and caused an 8-fold increase in monocyte NF-κB activation compared to supernatant. Macrophage TNF-α production was also increased after exposure to exosomes harvested in the resuscitation phase. The ML supernatant fraction had no effect on TNF-α production during any phase.

CONCLUSIONS

Our findings show that exosomes, and not the liquid fraction of ML, are the major component triggering inflammatory responses in monocytes and macrophages after experimental T/HS.

Duration of red blood cell storage and inflammatory marker generation

Red blood cell (RBC) transfusion is a life-saving treatment for several pathologies. RBCs for transfusion are stored refrigerated in a preservative solution, which extends their shelf-life for up to 42 days. During storage, the RBCs endure abundant physicochemical changes, named RBC storage lesions, which affect the overall quality standard, the functional integrity and in vivo survival of the transfused RBCs. Some of the changes occurring in the early stages of the storage period (for approximately two weeks) are reversible but become irreversible later on as the storage is extended. In this review, we aim to decipher the duration of RBC storage and inflammatory marker generation. This phenomenon is included as one of the causes of transfusion-related immunomodulation (TRIM), an emerging concept developed to potentially elucidate numerous clinical observations that suggest that RBC transfusion is associated with increased inflammatory events or effects with clinical consequence.

Distribution of local anesthetics between aqueous and liposome phases

Liposomes were used as biomimetic models in capillary electrokinetic chromatography (EKC) for the determination of distribution constants (K_D) of certain local anesthetics and a commonly used preservative. Synthetic liposomes comprised phosphatidylcholine and phosphatidylglycerol phospholipids with and without cholesterol. In addition, ghost liposomes made from red blood cell (RBC) lipid extracts were used as pseudostationary phase to acquire information on how the liposome composition affects the interactions between anesthetics and liposomes. These results were compared with theoretical distribution coefficients at pH 7.4. In addition to 25°C, the distribution constants were determined at 37 and 42°C to simulate physiological conditions. Moreover, the usability of five electroosmotic flow markers in liposome (LEKC) and micellar EKC (MEKC) was studied. LEKC was proven to be a convenient and fast technique for obtaining data about the distribution constants of local anesthetics between liposome and aqueous phase. RBC liposomes can be utilized for more representative model of cellular membranes, and the results indicate that the distribution constants of the anesthetics are greatly dependent on the used liposome composition and the amount of cholesterol, while the effect of temperature on the distribution constants is less significant.

Donor-variation effect on red blood cell storage lesion: A close relationship emerges

Although the molecular pathways leading to the progressive deterioration of stored red blood cells (RBC storage lesion) and the clinical relevance of storage-induced changes remain uncertain, substantial donor-specific variability in RBC performance during storage, and posttransfusion has been established ("donor-variation effect"). In-bag hemolysis and numerous properties of the RBC units that may affect transfusion efficacy have proved to be strongly donor-specific. Donor-variation effect may lead to the production of highly unequal blood labile products even when similar storage strategy and duration are applied. Genetic, undiagnosed/subclinical medical conditions and lifestyle factors that affect RBC characteristics at baseline, including RBC lifespan, energy metabolism, and sensitivity to oxidative stress, are all likely to influence the storage capacity of individual donors' cells, although not evident by the donor's health or hematological status at blood donation. Consequently, baseline characteristics of the donors, such as membrane peroxiredoxin-2 and serum uric acid concentration, have been proposed as candidate biomarkers of storage quality. This review article focuses on specific factors that might contribute to the donor-variation effect and emphasizes the emerging need for using omics-based technologies in association with in vitro and in vivo transfusion models and clinical trials to discover biomarkers of storage quality and posttransfusion recovery in donor blood.

Introduction to Extracellular Vesicles: Biogenesis, RNA Cargo Selection, Content, Release, and Uptake

Extracellular vesicles are a heterogeneous group of membrane-limited vesicles loaded with various proteins, lipids, and nucleic acids. Release of extracellular vesicles from its cell of origin occurs either through the outward budding of the plasma membrane or through the inward budding of the endosomal membrane, resulting in the formation of multivesicular bodies, which release vesicles upon fusion with the plasma membrane. The release of vesicles can facilitate intercellular communication by contact with or by internalization of contents, either by fusion with the plasma membrane or by endocytosis into "recipient" cells. Although the interest in extracellular vesicle research is increasing, there are still no real standards in place to separate or classify the different types of vesicles. This review provides an introduction into this expanding and complex field of research focusing on the biogenesis, nucleic acid cargo loading, content, release, and uptake of extracellular vesicles.

Molecular mechanisms of erythrocyte aging

Anemia and hemorrhagic shock are leading causes of morbidity and mortality worldwide, and transfusion of human blood products is the ideal treatment for these conditions. As human erythrocytes age during storage in blood banks they undergo many biochemical and structural changes, termed the red blood cell 'storage lesion'. Specifically, ATP and pH levels decrease as metabolic end products, oxidative stress, cytokines, and cell-free hemoglobin increase. Also, membrane proteins and lipids undergo conformational and organizational changes that result in membrane loss, viscoelastic changes and microparticle formation. As a result, transfusion of aged blood is associated with a host of adverse consequences such as decreased tissue perfusion, increased risk of infection, and increased mortality. This review summarizes current research detailing the known parts of the erythrocyte storage lesion and their physiologic consequences.

Analysis of the Secretome of Apoptotic Peripheral Blood Mononuclear Cells: Impact of Released Proteins and Exosomes for Tissue Regeneration

We previously showed that, when peripheral blood mononuclear cells (PBMCs) were stressed with ionizing radiation, they released paracrine factors that showed regenerative capacity in vitro and in vivo. This study aimed to characterize the secretome of PBMCs and to investigate its biologically active components in vitro and vivo. Bioinformatics analysis revealed that irradiated PBMCs differentially expressed genes that encoded secreted proteins. These genes were primarily involved in (a) pro-angiogenic and regenerative pathways and (b) the generation of oxidized phospholipids with known pro-angiogenic and inflammation-modulating properties. Subsequently, in vitro assays showed that the exosome and protein fractions of irradiated and non-irradiated PBMC secretome were the major biological components that enhanced cell mobility; conversely, secreted lipids and microparticles had no effects. We tested a viral-cleared PBMC secretome, prepared according to good manufacturing practice (GMP), in a porcine model of closed chest, acute myocardial infarction. We found that the potency for preventing ventricular remodeling was similar with the GMP-compliant and experimentally-prepared PBMC secretomes. Our results indicate that irradiation modulates the release of proteins, lipid-mediators and extracellular vesicles from human PBMCs. In addition our findings implicate the use of secretome fractions as valuable material for the development of cell-free therapies in regenerative medicine.

Blood Bag Plasticizers Influence Red Blood Cell Vesiculation Rate without Altering the Lipid Composition of the Vesicles

BACKGROUND

Polyvinyl chloride (PVC) plasticized with di(2-ethylhexyl) phthalate (DEHP) is commonly used for blood collection and storage. DEHP has protective effects on RBC membranes, but is also a toxin.

METHODS

A paired study was conducted to investigate the influence of DEHP and two alternative plasticizers, 1,2-cyclohexane-dicarboxylic acid diisononyl ester (DINCH) and n-butyryl-tri-n-hexyl citrate (BTHC), on the preservation of RBCs stored for 42 days in PVC pediatric bags. The RBC membrane was evaluated for supernatant hemoglobin (Hb), release of extracellular microvesicles (EVs), osmotic fragility, deformability, and lipid composition.

RESULTS

In BTHC-plasticized bags, the supernatant Hb increase during storage was 2 times greater than in DINCH- and DEHP-plasticized bags. By day 21, EV concentrations had doubled from day-5 levels in DINCH- and DEHP-, and trebled in BTHC-plasticized bags. RBC mean cell volumes were greater in BTHC- than in DINCH- or DEHP-plasticized bags (p < 0.001). Osmotic fragility differed significantly among plasticizers (p < 0.01). After day 21, RBC deformability decreased in all, but to a greater extent in the bags with BTHC. Phospholipid composition of RBCs and EVs was not different among plasticizers.

CONCLUSION

Membrane stabilization capacity differed among the plasticizers. RBC in BTHC bags stored more poorly, while DEHP and DINCH bags offered better protection against vesiculation, osmotic stress, and Hb loss.

Extracellular Vesicles: Composition, Biological Relevance, and Methods of Study

The release of extracellular vesicles (EVs), including exosomes and microvesicles, is a phenomenon shared by many cell types as a means of communicating with other cells and also potentially removing cell contents. The cargo of EVs includes the proteins, lipids, nucleic acids, and membrane receptors of the cells from which they originate. EVs released into the extracellular space can enter body fluids and potentially reach distant tissues. Once taken up by neighboring and/or distal cells, EVs can transfer functional cargo that may alter the status of recipient cells, thereby contributing to both physiological and pathological processes. In this article, we will focus on EV composition, mechanisms of uptake, and their biological effects on recipient cells. We will also discuss established and recently developed methods used to study EVs, including isolation, quantification, labeling and imaging protocols, as well as RNA analysis.

Buffy coat (top/bottom)- and whole-blood filtration (top/top)-produced red cell concentrates differ in size of extracellular vesicles

BACKGROUND AND OBJECTIVES

The influence that blood component separation methods have on changes to the red blood cell membrane during storage is not well understood. In Canada, red cell concentrates (RCCs) are produced using the buffy coat (BC, top/bottom) and the whole-blood filtration (WBF, top/top) methods, and this study aimed at comparing their influence on the characteristics of the extracellular vesicles (EV) which accumulated in the respective products during storage.

MATERIALS AND METHODS

Using flow cytometry, dynamic light scattering and mass spectrometry, we assessed RCC EVs for concentration, size, lipid composition and correlation with supernatant haemoglobin (Hb).

RESULTS

Accumulation of RBC EVs (CD235a(+) ) with storage time was similar in WBF and BC RCCs. The size of the EVs changed from <100 nm at d5 to near 200 nm by d42, with the EVs from WBF being smaller (P < 0·001) than BC RCCs at all storage times. The amount of EV-bound Hb in the WBF and BC units was similar (about 10% of total supernatant Hb). WBF EVs and BC EVs displayed similar lipid composition.

CONCLUSION

Haemolysis and EVs increase in BC and WBF RCCs during storage. Differences in the size characteristics of the EVs in WBF and BC RCCs suggest that non-RBC EVs are more prevalent in WBF products. Understanding the impact that manufacturing has on the characteristics of the different populations of EVs in RCCs will aid quality improvement efforts.

Routine storage of red blood cell (RBC) units in additive solution-3: a comprehensive investigation of the RBC metabolome

BACKGROUND

In most countries, red blood cells (RBCs) can be stored up to 42 days before transfusion. However, observational studies have suggested that storage duration might be associated with increased morbidity and mortality. While clinical trials are under way, impaired metabolism has been documented in RBCs stored in several additive solutions (ASs). Here we hypothesize that, despite reported beneficial effects, storage in AS-3 results in metabolic impairment weeks before the end of the unit shelf life.

STUDY DESIGN AND METHODS

Five leukofiltered AS-3 RBC units were sampled before, during, and after leukoreduction Day 0 and then assayed on a weekly basis from storage Day 1 through Day 42. RBC extracts and supernatants were assayed using a ultra-high-performance liquid chromatography separations coupled online with mass spectrometry detection metabolomics workflow.

RESULTS

Blood bank storage significantly affects metabolic profiles of RBC extracts and supernatants by Day 14. In addition to energy and redox metabolism impairment, intra- and extracellular accumulation of amino acids was observed proportionally to storage duration, suggesting a role for glutamine and serine metabolism in aging RBCs.

CONCLUSION

Metabolomics of stored RBCs could drive the introduction of alternative ASs to address some of the storage-dependent metabolic lesions herein reported, thereby increasing the quality of transfused RBCs and minimizing potential links to patient morbidity.

Metabolomics of AS-5 RBC supernatants following routine storage

BACKGROUND AND OBJECTIVES

The safety and efficacy of stored red blood cells (RBCs) transfusion has been long debated due to retrospective clinical evidence and laboratory results, indicating a potential correlation between increased morbidity and mortality following transfusion of RBC units stored longer than 14 days. We hypothesize that storage in Optisol additive solution-5 leads to a unique metabolomics profile in the supernatant of stored RBCs.

MATERIALS AND METHODS

Whole blood was drawn from five healthy donors, RBC units were manufactured, and prestorage leucoreduced by filtration. Samples were taken on days 1 and 42, the cells removed, and mass spectrometry-based metabolomics was performed.

RESULTS

The results confirmed the progressive impairment of RBC energy metabolism by day 42 with indirect markers of a parallel alteration of glutathione and NADPH homeostasis. Moreover, oxidized pro-inflammatory lipids accumulated by the end of storage.

CONCLUSION

The supernatants from stored RBCs may represent a burden to the transfused recipients from a metabolomics standpoint.

Storage of Red Blood Cells and Transfusion-Related Acute Lung Injury

Transfusion-related acute lung injury (TRALI) is a major complication post-transfusion. A consensus definition of TRALI has been recently established to improve diagnosis but the pathogenesis of TRALI is yet to be understood. Although the antibody-mediated two-hit model of TRALI is the classical narrative, increasing evidence of the probable implications of prolonged storage of blood provides novel mechanisms towards storage lesion- the potentially injurious cellular and biochemical changes that occur in stored red blood cells. Red blood cell-derived lipids and micro vesicles may have been playing an important role in the development of TRALI. This article will provide a brief overview of the current understanding of TRALI and then discuss the implications and the potential mechanisms by which stored red blood cells may lead to TRALI.

Measures of stored red blood cell quality

Blood banking underpins modern medical care, but blood storage, necessary for testing and inventory management, reduces the safety and efficacy of individual units of red blood cells (RBCs). Stored RBCs are damaged by the accumulation of their own waste products, by enzymatic and oxidative injury, and by metabolically programmed cell death. These chemical activities lead to a complex RBC storage lesion that includes haemolysis, reduced in vivo recovery, energy and membrane loss, altered oxygen release, reduced adenosine tri-phosphate and nitric oxide secretion, and shedding of toxic products. These toxic products include lysophospholipids that can cause transfusion-related acute lung injury, free iron that can potentiate infections and cause inflammation, and shed microvesicles that can scavenge nitric oxide and potentiate inflammation and thrombosis. However, most of the obvious negative outcomes of RBC storage are uncommon and appear to be related to exceptionally bad units. Generally, the quality of stored RBCs is highly related to the conditions of storage, so refrigerator temperature, intact bags, residual leucocyte counts and visible haemolysis remain excellent general measures. Specific biochemical measures, such as adenosine 5'-triphosphate (ATP) and 2,3-diphosphoglycerate (DPG) concentrations, calcium and potassium content or lipid breakdown products, require specialized measures that are not widely available, involve destructive testing and generally reflect only a part of the storage lesion. This review describes a number of components of the storage lesion and their measurement and attempts to access the utility of the measures.

The effects of rejuvenation during hypothermic storage on red blood cell membrane remodeling

BACKGROUND

Our previous studies showed that hypothermic storage (HS) induces red blood cell (RBC) microparticle (RMP) generation and changes in phosphatidylserine (PS) and CD47 expression on RBCs and RMPs. The aim of this study was to evaluate the effect of cold rejuvenation treatment at multiple time points during storage on these prehemolytic indicators of RBC membrane storage lesion.

STUDY DESIGN AND METHODS

Leukoreduced RBC units in saline-adenine-glucose-mannitol were used to generate three groups: untreated controls, sham-treated units, and units treated with a cold (1-6°C) rejuvenation solution on Day 28, 35, or 42 of HS. Units were assessed for hemolysis, adenosine triphosphate (ATP) concentration, lipid composition, and RMP generation, as well as PS and CD47 expression throughout 49 days of HS.

RESULTS

Rejuvenation treatment led to a significant increase in ATP concentration in all units, irrespective of treatment day. There were no significant differences between sham- and rejuvenation-treated RBC samples in the levels of PS externalization, CD47 expression, or the rate of RMP formation. RBCs rejuvenated on Day 28 were enriched in glycerophosphocholine (+23.5%), depleted in sphingomyelin (-14%), and slightly depleted in cholesterol (-3.5%).

CONCLUSION

Cold rejuvenation in hypothermically stored RBCs affects the lipid composition of RBCs and respective RMPs in a time-dependent fashion.

Exosomes as new vesicular lipid transporters involved in cell-cell communication and various pathophysiologies

Exosomes are nanovesicles that have emerged as a new intercellular communication system between an intracellular compartment of a donor cell towards the periphery or an internal compartment of a recipient cell. The bioactivity of exosomes resides not only in their protein and RNA contents but also in their lipidic molecules. Exosomes display original lipids organized in a bilayer membrane and along with the lipid carriers such as fatty acid binding proteins that they contain, exosomes transport bioactive lipids. Exosomes can vectorize lipids such as eicosanoids, fatty acids, and cholesterol, and their lipid composition can be modified by in-vitro manipulation. They also contain lipid related enzymes so that they can constitute an autonomous unit of production of various bioactive lipids. Exosomes can circulate between proximal or distal cells and their fate can be regulated in part by lipidic molecules. Compared to their parental cells, exosomes are enriched in cholesterol and sphingomyelin and their accumulation in cells might modulate recipient cell homeostasis. Exosome release from cells appears to be a general biological process. They have been reported in all biological fluids from which they can be recovered and can be monitors of specific pathophysiological situations. Thus, the lipid content of circulating exosomes could be useful biomarkers of lipid related diseases. Since the first lipid analysis of exosomes ten years ago detailed knowledge of exosomal lipids has accumulated. The role of lipids in exosome fate and bioactivity and how they constitute an additional lipid transport system are considered in this review.

Challenges for red blood cell biomarker discovery through proteomics

Red blood cells are rather unique body cells, since they have lost all organelles when mature, which results in lack of potential to replace proteins that have lost their function. They maintain only a few pathways for obtaining energy and reducing power for the key functions they need to fulfill. This makes RBCs highly sensitive to any aberration. If so, these RBCs are quickly removed from circulation, but if the RBC levels reduce extremely fast, this results in hemolytic anemia. Several causes of HA exist, and proteome analysis is the most straightforward way to obtain deeper insight into RBC functioning under the stress of disease. This should result in discovery of biomarkers, typical for each source of anemia. In this review, several challenges to generate in-depth RBC proteomes are described, like to obtain pure RBCs, to overcome the wide dynamic range in protein expression, and to establish which of the identified/quantified proteins are active in RBCs. The final challenge is to acquire and validate suited biomarkers unique for the changes that occur for each of the clinical questions; in red blood cell aging (also important for transfusion medicine), for thalassemias or sickle cell disease. Biomarkers for other hemolytic anemias that are caused by dysfunction of RBC membrane proteins (the RBC membrane defects) or RBC cytosolic proteins (the enzymopathies) are sometimes even harder to discover, in particular for the patients with RBC rare diseases with unknown cause. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.