Microparticles from stored red blood cells enhance procoagulant and proinflammatory activity

Analysis of non-physiological shear stress-induced red blood cell trauma across different clinical support conditions of the blood pump

Systematic research into device-induced red blood cell (RBC) damage beyond hemolysis, including correlations between hemolysis and RBC-derived extracellular vesicles, remains limited. This study investigated non-physiological shear stress-induced RBC damage and changes in related biochemical indicators under two blood pump clinical support conditions. Pressure heads of 100 and 350 mmHg, numerical simulation methods, and two in vitro loops were utilized to analyze the shear stress and changes in RBC morphology, hemolysis, biochemistry, metabolism, and oxidative stress. The blood pump created higher shear stress in the 350-mmHg condition than in the 100-mmHg condition. With prolonged blood pump operation, plasma-free hemoglobin and cholesterol increased, whereas plasma glucose and nitric oxide decreased in both loops. Notably, plasma iron and triglyceride concentrations increased only in the 350-mmHg condition. The RBC count and morphology, plasma lactic dehydrogenase, and oxidative stress across loops did not differ significantly. Plasma extracellular vesicles, including RBC-derived microparticles, increased significantly at 600 min in both loops. Hemolysis correlated with plasma triglyceride, cholesterol, glucose, and nitric oxide levels. Shear stress, but not oxidative stress, was the main cause of RBC damage. Hemolysis alone inadequately reflects overall blood pump-induced RBC damage, suggesting the need for additional biomarkers for comprehensive assessments.

Need for Blood Transfusion Volume Is Associated With Increased Mortality in Severe Traumatic Brain Injury

INTRODUCTION

Many patients suffering from isolated severe traumatic brain injury (sTBI) receive blood transfusion on hospital arrival due to hypotension. We hypothesized that increasing blood transfusions in isolated sTBI patients would be associated with an increase in mortality.

METHODS

We performed a trauma quality improvement program (TQIP) (2017-2019) and single-center (2013-2021) database review filtering for patients with isolated sTBI (Abbreviated Injury Scale head ≥3 and all other areas ≤2). Age, initial Glasgow Coma Score (GCS), Injury Severity Score (ISS), initial systolic blood pressure (SBP), mechanism (blunt/penetrating), packed red blood cells (pRBCs) and fresh frozen plasma (FFP) transfusion volume (units) within the first 4 h, FFP/pRBC ratio (4h), and in-hospital mortality were obtained from the TQIP Public User Files.

RESULTS

In the TQIP database, 9257 patients had isolated sTBI and received pRBC transfusion within the first 4 h. The mortality rate within this group was 47.3%. The increase in mortality associated with the first unit of pRBCs was 20%, then increasing approximately 4% per unit transfused to a maximum mortality of 74% for 11 or more units. When adjusted for age, initial GCS, ISS, initial SBP, and mechanism, pRBC volume (1.09 [1.08-1.10], FFP volume (1.08 [1.07-1.09]), and FFP/pRBC ratio (1.18 [1.08-1.28]) were associated with in-hospital mortality. Our single-center study yielded 138 patients with isolated sTBI who received pRBC transfusion. These patients experienced a 60.1% in-hospital mortality rate. Logistic regression corrected for age, initial GCS, ISS, initial SBP, and mechanism demonstrated no significant association between pRBC transfusion volume (1.14 [0.81-1.61]), FFP transfusion volume (1.29 [0.91-1.82]), or FFP/pRBC ratio (6.42 [0.25-164.89]) and in-hospital mortality.

CONCLUSIONS

Patients suffering from isolated sTBI have a higher rate of mortality with increasing amount of pRBC or FFP transfusion within the first 4 h of arrival.

Whole blood storage duration alters fibrinogen levels and thrombin formation

INTRODUCTION

Whole blood resuscitation for hemorrhagic shock in trauma represents an opportunity to correct coagulopathy in trauma while also supplying red blood cells. The production of microvesicles in stored whole blood and their effect on its hemostatic parameters have not been described in previous literature. We hypothesized that microvesicles in aged stored whole blood are procoagulant and increase thrombin production via phosphatidylserine.

METHODS

Whole blood was obtained from male C57BL/6 male mice and stored in anticoagulant solution for up to 10 days. At intervals, stored whole blood underwent examination with rotational thromboelastography, and platelet-poor plasma was prepared for analysis of thrombin generation. Microvesicles were prepared from 10-day-old whole blood aliquots and added to fresh whole blood or platelet-poor plasma to assess changes in coagulation and thrombin generation. Microvesicles were treated with recombinant mouse lactadherin prior to addition to plasma to inhibit phosphatidylserine's role in thrombin generation.

RESULTS

Aged murine whole blood had decreased fibrin clot formation compared with fresh samples with decreased plasma fibrinogen levels. Thrombin generation in plasma from aged blood increased over time of storage. The addition of microvesicles to fresh plasma resulted in increased thrombin generation compared with controls. When phosphatidylserine on microvesicles was blocked with lactadherin, there was no difference in the endogenous thrombin potential, but the generation of thrombin was blunted with lower peak thrombin levels.

CONCLUSION

Cold storage of murine whole blood results in decreased fibrinogen levels and fibrin clot formation. Aged whole blood demonstrates increased thrombin generation, and this is due in part to microvesicle production in stored whole blood. One mechanism by which microvesicles are procoagulant is by phosphatidylserine expression on their membranes.

Impact of production methods and storage conditions on extracellular vesicles in packed red blood cells and platelet concentrates

The use of blood and blood products can be life-saving, but there are also certain risks associated with their administration and use. Packed red blood cells (pRBCs) and platelet concentrates are the most commonly used blood products in transfusion medicine to treat anemia or acute and chronic bleeding disorders, respectively. During the production and storage of blood products, red blood cells and platelets release extracellular vesicles (EVs) as a result of the storage lesion, which may affect product quality. EVs are subcellular structures enclosed by a lipid bilayer and originate from the endosomal system or from the plasma membrane. They play a pivotal role in intercellular communication and are emerging as important regulators of inflammation and coagulation. Their cargo and their functional characteristics depend on the cell type from which they originate, as well as on their microenvironment, influencing their capacity to promote coagulation and inflammatory responses. Hence, the potential involvement of EVs in transfusion-related adverse events is increasingly recognized and studied. Here, we review the knowledge regarding the effect of production and storage conditions of pRBCs and platelet concentrates on the release of EVs. In this context, the mode of processing and anticoagulation, the influence of additive solutions and leukoreduction, as well as the storage duration will be addressed, and we discuss potential implications of EVs for the clinical outcome of transfusion.

Evaluating the effects of hypoxic storage on platelet function and health using a novel storage system

BACKGROUND

Thousands of units of whole blood (WB) and blood components are transfused daily to treat trauma patients. Improved methods for blood storage are critical to support trauma-related care. The Hemanext ONE® system offers a unique method for hypoxic storage of WB, with successfully demonstrated storage of clinically viable RBCs. This work evaluated the system for the storage of WB, focusing on platelet health and function.

STUDY DESIGN AND METHODS

WB was collected from healthy donors and processed through the Hemanext ONE® system. Hemoglobin oxygen saturation (HbSO2) levels of WB were depleted to 10%, 20%, or 30% of total HbSO2 and then stored in PVC bags sealed in oxygen-impermeable bags (except for normoxic control) with samples collected on days 1, 7, and 14 post-processing. Flow cytometry assessed the activation and apoptosis of platelets. Clot dynamics were assessed based on aggregometry and thromboelastography assays, as well as thrombin generation using a calibrated-automated thrombogram method.

RESULTS

Hypoxic storage conditions were maintained throughout the storage period. Hypoxia triggered increased lactate production, but pH changes were negligible compared to normoxic control. Storage at 10% HbSO2 had a significant impact on platelet function, resulting in increased activation and reduced clot formation and aggregation. These effects were less significant at 20% and 30% HbSO2.

DISCUSSION

This study indicates that platelets are sensitive to hypoxic storage and suffer significant metabolic and functional deterioration when stored at or below 10% HbSO2.

Adverse effects of microparticles on transfusion of stored red blood cell concentrates

BACKGROUND

Systemic and pulmonary coagulopathy and inflammation are important characteristics of transfusion-related acute lung injury (TRALI). Whether microparticles that accumulate in transfused red blood cell concentrates (RBCs) have proinflammatory and procoagulant potential and contribute to adverse reactions of RBC transfusions is unclear.

AIM

To investigate the ability of microparticles in stored RBCs to promote thrombin generation and induce human pulmonary microvascular endothelial cell (HMVEC) activation and damage.

METHODS

The number and size of microparticles were determined by flow cytometric and nanoparticle tracking analyses, respectively. Thrombin generation and the intrinsic coagulation pathway were assayed by a calibrated automated thrombogram and by measuring activated partial thromboplastin time (aPTT), respectively. The expression of ICAM-1 and the release of cytokines by endothelial cells were detected by flow cytometric analyses. HMVEC damage was assessed by incubating lipopolysaccharide-activated endothelial cells with MP-primed polymorphonuclear neutrophils (PMNs).

RESULTS

The size of the microparticles in the RBC supernatant was approximately 100-300 nm. Microparticles promoted thrombin generation in a dose-dependent manner and the aPTT was shortened. Depleting microparticles from the supernatant of RBCs stored for 35 days by either filtration or centrifugation significantly decreased the promotion of thrombin generation. The expression of ICAM-1 on HMVECs was increased significantly by incubation with isolated microparticles. Furthermore, microparticles induced the release of interleukin-6 (IL-6) and interleukin-8 (IL-8) from HMVECs. Microparticles induced lipopolysaccharide-activated HMVEC damage by priming PMNs, but this effect was prevented by inhibiting the PMNs respiratory burst with apocynin.

CONCLUSION

Microparticles in stored RBCs promote thrombin generation, HMVEC activation and damage which may be involved in TRALI development.

Vesiculation in irradiated and cation-leaky-stored red blood cells

BACKGROUND

Extracellular vesicles (EVs) are released by red blood cells (RBCs) throughout their life-span and also during hypothermic storage when they accumulate in the blood bag. We queried whether stored RBCs with increased cation permeability, either from donors with familial pseudohyperkalaemia (FP) or caused by irradiation, vesiculate more readily.

STUDY DESIGN AND METHODS

Recent technical advances have revealed at least two sub-populations of MVs in RBC storage units: macrovesicles (2-6 μm) and microvesicles (1-2 μm). Using nanoparticle tracking analysis, imaging flow cytometry, and protein quantification methods, we measured and characterized vesicles released by RBCs from control and FP individuals at three different storage time-points (day 4, day 17, and day 29). The RBCs had either been stored untreated or irradiated on either day 1 or day 14 of storage.

RESULTS

We found no difference in the number or size of vesicles released between cation-leaky FP RBCs and non-FP controls. Similarly, irradiated and non-irradiated RBCs showed very similar patterns of vesicle release to during cold-storage. The only significant difference in vesicle release was the increase in accumulated vesicles with length of storage time which has been reported previously.

DISCUSSION

EVs in stored blood are potential contributors to adverse transfusion reactions. The number of vesicles released during 35-day hypothermic storage varies between donors and increases with storage duration. However, increased cation permeability and irradiation do not appear to affect vesicle formation during RBC cold-storage.

Red Blood Cell-Derived Extracellular Vesicles: An Overview of Current Research Progress, Challenges, and Opportunities

Red blood cell-derived extracellular vesicles (RBC EVs) are small, spherical fragments released from red blood cells. These vesicles, similar to EVs derived from other cell types, are crucial for intercellular communication processes and have been implicated in various physiological and pathological processes. The diagnostic and therapeutic potential of RBC EVs has garnered increasing attention in recent years, revealing their valuable role in the field of medicine. In this review, we aim to provide a comprehensive analysis of the current research status of RBC EVs. We summarize existing studies and highlight the progress made in understanding the characteristics and functions of RBC EVs, with a particular focus on their biological roles in different diseases. We also discuss their potential utility as diagnostic and prognostic biomarkers in diseases and as vectors for drug delivery. Furthermore, we emphasize the need for further research to achieve selective purification of RBC EVs and unravel their heterogeneity, which will allow for a deeper understanding of their diverse functions and exploration of their potential applications in diagnostics and therapeutics.

Extracellular vesicles: effectors of transfusion-related acute lung injury

Respiratory transfusion reactions represent some of the most severe adverse reactions related to receiving blood products. Of those, transfusion-related acute lung injury (TRALI) is associated with elevated morbidity and mortality. TRALI is characterized by severe lung injury associated with inflammation, pulmonary neutrophil infiltration, lung barrier leak, and increased interstitial and airspace edema that cause respiratory failure. Presently, there are few means of detecting TRALI beyond clinical definitions based on physical examination and vital signs or preventing/treating TRALI beyond supportive care with oxygen and positive pressure ventilation. Mechanistically, TRALI is thought to be mediated by the culmination of two successive proinflammatory hits, which typically comprise a recipient factor (1st hit-e.g., systemic inflammatory conditions) and a donor factor (2nd hit-e.g., blood products containing pathogenic antibodies or bioactive lipids). An emerging concept in TRALI research is the contribution of extracellular vesicles (EVs) in mediating the first and/or second hit in TRALI. EVs are small, subcellular, membrane-bound vesicles that circulate in donor and recipient blood. Injurious EVs may be released by immune or vascular cells during inflammation, by infectious bacteria, or in blood products during storage, and can target the lung upon systemic dissemination. This review assesses emerging concepts such as how EVs: 1) mediate TRALI, 2) represent targets for therapeutic intervention to prevent or treat TRALI, and 3) serve as biochemical biomarkers facilitating TRALI diagnosis and detection in at-risk patients.

Cellular nanovesicles for therapeutic immunomodulation: A perspective on engineering strategies and new advances

Cellular nanovesicles which are referred to as cell-derived, nanosized lipid bilayer structures, have emerged as a promising platform for regulating immune responses. Owing to their outstanding advantages such as high biocompatibility, prominent structural stability, and high loading capacity, cellular nanovesicles are suitable for delivering various immunomodulatory molecules, such as small molecules, nucleic acids, peptides, and proteins. Immunomodulation induced by cellular nanovesicles has been exploited to modulate immune cell behaviors, which is considered as a novel cell-free immunotherapeutic strategy for the prevention and treatment of diverse diseases. Here we review emerging concepts and new advances in leveraging cellular nanovesicles to activate or suppress immune responses, with the aim to explicate their applications for immunomodulation. We overview the general considerations and principles for the design of engineered cellular nanovesicles with tailored immunomodulatory activities. We also discuss new advances in engineering cellular nanovesicles as immunotherapies for treating major diseases.

Extracellular Vesicles as New Players in Drug Delivery: A Focus on Red Blood Cells-Derived EVs

The article is divided into several sections, focusing on extracellular vesicles' (EVs) nature, features, commonly employed methodologies and strategies for their isolation/preparation, and their characterization/visualization. This work aims to give an overview of advances in EVs' extensive nanomedical-drug delivery applications. Furthermore, considerations for EVs translation to clinical application are summarized here, before focusing the review on a special kind of extracellular vesicles, the ones derived from red blood cells (RBCEVs). Generally, employing EVs as drug carriers means managing entities with advantageous properties over synthetic vehicles or nanoparticles. Besides the fact that certain EVs also reveal intrinsic therapeutic characteristics, in regenerative medicine, EVs nanosize, lipidomic and proteomic profiles enable them to pass biologic barriers and display cell/tissue tropisms; indeed, EVs engineering can further optimize their organ targeting. In the second part of the review, we focus our attention on RBCEVs. First, we describe the biogenesis and composition of those naturally produced by red blood cells (RBCs) under physiological and pathological conditions. Afterwards, we discuss the current procedures to isolate and/or produce RBCEVs in the lab and to load a specific cargo for therapeutic exploitation. Finally, we disclose the most recent applications of RBCEVs at the in vitro and preclinical research level and their potential industrial exploitation. In conclusion, RBCEVs can be, in the near future, a very promising and versatile platform for several clinical applications and pharmaceutical exploitations.

Shear stimulated red blood cell microparticles: Effect on clot structure, flow and fibrinolysis

BACKGROUND

Microparticles (MPs) have activity in thrombus promotion and generation. Erythrocyte microparticles (ErMPs) have been reported to accelerate fibrinolysis in the absence of permeation. We hypothesized that shear induced ErMPs would affect fibrin structure of clots and change flow with implications for fibrinolysis.

OBJECTIVE

To determine the effect of ErMPs on clot structure and fibrinolysis.

METHODS

Plasma with elevated ErMPs was isolated from whole blood or from washed red blood cells (RBCs) resuspended in platelet free plasma (PFP) after high shear. Dynamic light scattering (DLS) provided size distribution of ErMPs from sheared samples and unsheared PFP controls. Clots were formed by recalcification for flow/lysis experiments and examined by confocal microscopy and SEM. Flow rates through clots and time-to-lysis were recorded. A cellular automata model showed the effect of ErMPs on fibrin polymerization and clot structure.

RESULTS

Coverage of fibrin increased by 41% in clots formed from plasma of sheared RBCs in PFP over controls. Flow rate decreased by 46.7% under a pressure gradient of 10 mmHg/cm with reduction in time to lysis from 5.7 ± 0.7 min to 12.2 ± 1.1 min (p < 0.01). Particle size of ErMPs from sheared samples (200 nm) was comparable to endogenous microparticles.

CONCLUSIONS

ErMPs alter the fibrin network in a thrombus and affect hydraulic permeability resulting in decelerated delivery of fibrinolytic drugs.

Extracellular vesicles participate in the pathogenesis of sepsis

Sepsis is one of the leading causes of mortality worldwide and is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. The early diagnosis and effective treatment of sepsis still face challenges due to its rapid progression, dynamic changes, and strong heterogeneity among different individuals. To develop novel strategies to control sepsis, a better understanding of the complex mechanisms of sepsis is vital. Extracellular vesicles (EVs) are membrane vesicles released from cells through different mechanisms. In the disease state, the number of EVs produced by activated or apoptotic cells and the cargoes they carry were altered. They regulated the function of local or distant host cells in autocrine or paracrine ways. Current studies have found that EVs are involved in the occurrence and development of sepsis through multiple pathways. In this review, we focus on changes in the cargoes of EVs in sepsis, the regulatory roles of EVs derived from host cells and bacteria, and how EVs are involved in multiple pathological processes and organ dysfunction in sepsis. Overall, EVs have great application prospects in sepsis, such as early diagnosis of sepsis, dynamic monitoring of disease, precise therapeutic targets, and prevention of sepsis as a vaccine platform.

Biomaterials-Enabled Antithrombotics: Recent Advances and Emerging Strategies

Antithrombotic and thrombolytic therapies are used to prevent, treat, and remove blood clots in various clinical settings, from emergent to prophylactic. While ubiquitous in their healthcare application, short half-lives, off-target effects, overdosing complications, and patient compliance continue to be major liabilities to the utility of these agents. Biomaterials-enabled strategies have the potential to comprehensively address these limitations by creating technologies that are more precise, durable, and safe in their antithrombotic action. In this review, we discuss the state of the art in anticoagulant and thrombolytic biomaterials, covering the nano to macro length scales. We emphasize current methods of formulation, discuss how material properties affect controlled release kinetics, and summarize modern mechanisms of clot-specific drug targeting. The preclinical efficacy of these technologies in an array of cardiovascular applications, including stroke, pulmonary embolism, myocardial infarction, and blood contacting devices, is summarized and performance contrasted. While significant advances have already been made, ongoing development efforts look to deliver bioresponsive "smart" biomaterials that will open new precision medicine opportunities in cardiology.

Storage with ethanol attenuates the red blood cell storage lesion

BACKGROUND

Current management of hemorrhagic shock relies on control of surgical bleeding along with resuscitation with packed red blood cells and plasma in a 1-to-1 ratio. Transfusion, however, is not without consequence as red blood cells develop a series of biochemical and physical changes during storage termed "the red blood cell storage lesion." Previous data has suggested that ethanol may stabilize the red blood cell membrane, resulting in improved deformability. We hypothesized that storage of packed red blood cells with ethanol would alter the red blood cell storage lesion.

METHODS

Mice underwent donation and storage of red blood cells with standard storage conditions in AS-3 alone or ethanol at concentrations of 0.07%, 0.14%, and 0.28%. The red blood cell storage lesion parameters of microvesicles, Band-3, free hemoglobin, annexin V, and erythrocyte osmotic fragility were measured and compared. In additional experiments, the mice underwent hemorrhage and resuscitation with stored packed red blood cells to further evaluate the in vivo inflammatory impact.

RESULTS

Red blood cells stored with ethanol demonstrated decreased microvesicle accumulation and Band-3 levels. There were no differences in phosphatidylserine or cell-free hemoglobin levels. After hemorrhage and resuscitation with packed red blood cells stored with 0.07% ethanol, mice demonstrated decreased serum levels of interleukin-6, macrophage inflammatory protein-1α, keratinocyte chemokine, and tumor necrosis factor α compared to those mice receiving packed red blood cells stored with additive solution-3.

CONCLUSION

Storage of murine red blood cells with low-dose ethanol results in decreased red blood cell storage lesion severity. Resuscitation with packed red blood cells stored with 0.07% ethanol also resulted in a decreased systemic inflammatory response in a murine model of hemorrhage.

The Effect of Extracellular Vesicles on Thrombosis

The risk of cardiovascular events caused by acute thrombosis is high, including acute myocardial infarction, acute stroke, acute pulmonary embolism, and deep vein thrombosis. In this review, we summarize the roles of extracellular vesicles of different cellular origins in various cardiovascular events associated with acute thrombosis, as described in the current literature, to facilitate the future development of a precise therapy for thrombosis caused by such vesicles. We hope that our review will indicate a new horizon in the field of cardiovascular research with regard to the treatment of acute thrombosis, especially targeting thrombosis caused by extracellular vesicles secreted by individual cells. As more emerging technologies are being developed, new diagnostic and therapeutic strategies related to EVs are expected to be identified for related diseases in the future.

Storage of packed red blood cells impairs an inherent coagulation property of erythrocytes

Storage of packed red blood cells is associated with changes in erythrocytes that over time increasingly impair cellular function and potentially contribute to adverse effects associated with blood transfusion. Exposure of phosphatidylserine at the outer membrane leaflet of erythrocytes and shedding of microvesicles (MVs) during packed red blood cell storage are alterations assumed to increase the risk of prothrombotic events in recipients. Here, we used rotational thromboelastometry to study the coagulation process in blood samples with erythrocytes from stored PRBCs reconstituted with freshly prepared platelet-rich plasma. We explored the influence of following effects on the coagulation process: 1) PRBC storage duration, 2) differences between erythrocytes from stored PRBCs compared to freshly drawn erythrocytes, and 3) the contribution of added MVs. Interestingly, despite of a higher fraction of PS-positive cells, erythrocytes from PRBCs stored for 6 weeks revealed longer clotting times than samples with erythrocytes stored for 2 or 4 weeks. Further, clotting times and clot formation times were considerably increased in samples reconstituted with erythrocytes from stored PRBCs as compared to fresh erythrocytes. Moreover, MVs added to reconstituted samples elicited only comparably small and ambiguous effects on coagulation. Thus, this study provides no evidence for an amplified clotting process from prolonged storage of PRBCs but on the contrary implicates a loss of function, which may be of clinical significance in massive transfusion. Our observations add to the increasing body of evidence viewing erythrocytes as active players in the clotting process.

Annexin V- and tissue factor+ microparticles as biomarkers for predicting deep vein thrombosis in patients after joint arthroplasty

OBJECTIVE

Venous thromboembolism (VTE) is a common and severe complication of joint arthroplasty. Microparticles (MPs) containing phosphatidylserine (PS) and tissue factor (TF) can trigger coagulation in VTE. This study aims to measure and compare MP levels in joint arthroplasty patients with and without VTE.

METHODS

This prospective cohort study enrolled 181 patients who underwent joint arthroplasty. Ultrasound examination was used to diagnose VTE on preoperative day 0 and postoperative day 6. MPs were analysed using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and flow cytometry. The levels of platelet-derived microparticles (PMPs), endothelial cell-derived microparticles (EMPs), granulocyte-derived microparticles (GMPs), red cell-derived microparticles (RMPs), monocyte-derived microparticles (MMPs), Annexin V⁺ MPs (AV⁺ MPs), and tissue factor⁺ MPs (TF⁺ MPs) derived from five kinds of MPs were measured on day 0 (before surgery), 1, 2, 3, 4, 5, and 6 after surgery.

RESULTS

The levels of AV^-TF⁺ EMPs and AV^-TF⁺ MMPs were significantly increased in patients with VTE on postoperative day 5 compared to those without VTE (P=0.031 and P=0.031, respectively).

CONCLUSION

AV^-TF⁺ MPs may indicate the development of VTE and serve as predictive markers in joint arthroplasty patients.

The regulatory role of exosomes in venous thromboembolism

Exosomes are nanoscale endocytic vesicles, 30-150 nm in diameter, secreted by most cells. They mainly originate from multivesicular bodies formed by intracellular invagination of lysosomal microparticles, and released into the extracellular matrix after fusion of multivesicular bodies with cell membrane. Studies have shown that exosomes contain a variety of active molecules, such as proteins, lipids and RNAs (such as mRNA, miRNA, lncRNA, circRNA, etc.), which regulate the behavior of recipient cells and serve as circulating biomarkers of diseases, including thrombosis. Therefore, exosome research is important for the diagnosis, treatment, therapeutic monitoring, and prognosis of thrombosis in that it can reveal the counts, surface marker expression, protein, and miRNA cargo involved. Recent studies have shown that exosomes can be used as therapeutic vectors for tissue regeneration and as alternative vectors for drug delivery. In this review, we summarize the physiological and biochemical characteristics, isolation, and identification of exosomes. Moreover, we focus on the role of exosomes in thrombosis, specifically venous thromboembolism, and their potential clinical applications, including as biomarkers and therapeutic vectors for thrombosis.

Red Blood Cell-Derived Microparticles Exert No Cancer Promoting Effects on Colorectal Cancer Cells In Vitro

The biomedical consequences of allogeneic blood transfusions and the possible pathomechanisms of transfusion-related morbidity and mortality are still not entirely understood. In retrospective studies, allogeneic transfusion was associated with increased rates of cancer recurrence, metastasis and death in patients with colorectal cancer. However, correlation does not imply causation. The purpose of this study was to elucidate this empirical observation further in order to address insecurity among patients and clinicians. We focused on the in vitro effect of microparticles derived from red blood cell units (RMPs). We incubated different colon carcinoma cells with RMPs and analyzed their effects on growth, invasion, migration and tumor marker expression. Furthermore, effects on Wnt, Akt and ERK signaling were explored. Our results show RMPs do not seem to affect functional and phenotypic characteristics of different colon carcinoma cells and did not induce or inhibit Wnt, Akt or ERK signaling, albeit in cell culture models lacking tumor microenvironment. Allogeneic blood transfusions are associated with poor prognosis, but RMPs do not seem to convey tumor-enhancing effects. Most likely, the circumstances that necessitate the transfusion, such as preoperative anemia, tumor stage, perioperative blood loss and extension of surgery, take center stage.

Roles and Applications of Red Blood Cell-Derived Extracellular Vesicles in Health and Diseases

Red blood cell-derived extracellular vesicles (RBCEVs) are vesicles naturally produced by red blood cells and play multiple roles such as acting as cell-to-cell communication messengers in both normal physiological and diseased states. RBCEVs are highly promising delivery vehicles for therapeutic agents such as biomolecules and nucleic acids as they are easy to source, safe, and versatile. RBCEVs autonomously target the liver and pass the blood-brain barrier into the brain, which is highly valuable for the treatment of liver and brain diseases. RBCEVs can be modified by various functional units, including various functional molecules and nanoparticles, to improve their active targeting capabilities for tumors or other sites. Moreover, the RBCEV level is significantly shifted in many diseased states; hence, they can also serve as important biomarkers for disease diagnoses. It is clear that RBCEVs have considerable potential in multiple medical applications. In this review, we briefly introduce the biological roles of RBCEVs, presented interesting advances in RBCEV applications, and discuss several challenges that need to be addressed for their clinical translation.

Erythrocyte-derived extracellular vesicles aggravate inflammation by promoting the proinflammatory macrophage phenotype through TLR4-MyD88-NF-κB-MAPK pathway

Transfusion of stored erythrocytes is associated with the increased risk of morbidity and mortality in critical infections, but the mechanism is incompletely understood. Previous studies have suggested that RBC-derived extracellular vesicles (EVs) may be potential risk factors for the occurrence of transfusion-related immunomodulation. The purpose of our study was to evaluate the effects of RBC-derived EVs under inflammatory conditions and explore the underlying mechanisms. In vivo, the activity of EVs was evaluated in cecal ligation and puncture (CLP)-induced sepsis. Our results showed that EVs significantly aggravated the inflammatory response to sepsis in serum and lung tissue by promoting the production of the proinflammatory factors tumor necrosis factor-α (TNF-α）-interleukin-6(IL-6), and interleukin-1β (IL-1β) and reduced the survival rate of septic mice in vivo. Importantly, adoptive transfer of EVs-pretreated bone marrow-derived macrophages (BMDMs) obviously aggravated systemic proinflammatory factors in mice after CLP surgery. In vitro, the proinflammatory properties of EVs were shown to elevate TNF-α, IL-6, and IL-1β levels in lipopolysaccharide (LPS)-stimulated BMDMs. Moreover, EVs promoted LPS-induced macrophage polarization into a proinflammatory phenotype. The underlying mechanism might involve EV-mediated up-regulation of TLR4-MyD88-NF-κB-MAPK activity to favor macrophage cytokine production.

Red blood cell-derived phosphatidylserine positive extracellular vesicles are associated with past thrombotic events in patients with systemic erythematous lupus

Background

Extracellular vesicles (EVs) released by blood cells have proinflammation and procoagulant action. Patients with systemic lupus erythematosus (SLE) present high vascular inflammation and are prone to develop cardiovascular diseases. Therefore, we postulated that the EV populations found in blood, including platelet EVs (PEVs) and red blood cell EVs (REVs), are associated with SLE disease activity and SLE-associated cardiovascular accidents.

Method

We assessed autotaxin (ATX) plasma levels by ELISA, the platelet activation markers PAC1 and CD62P, ATX bound to platelets and the amounts of plasma PEVs and REVs by flow cytometry in a cohort of 102 patients with SLE, including 29 incident cases of SLE and 30 controls. Correlation analyses explored the associations with the clinical parameters.

Result

Platelet activation markers were increased in patients with SLE compared with healthy control, with the marker CD62P associated with the SLE disease activity index (SLEDAI). The incident cases show additional associations between platelet markers (CD62P/ATX and PAC1/CD62P) and the SLEDAI. Compared with controls, patients with SLE presented higher levels of PEVs, phosphatidylserine positive (PS⁺) PEVs, REVs and PS⁺ REVs, but there is no association with disease activity. When stratified according to the plasma level of PS⁺ REVs, the group of patients with SLE with a high level of PS⁺ REVs presented a higher number of past thrombosis events and higher ATX levels.

Conclusion

Incident and prevalent forms of SLE cases present similar levels of platelet activation markers, with CD62P correlating with disease activity. Though EVs are not associated with disease activity, the incidence of past thrombotic events is higher in patients with a high level of PS⁺ REVs.

X- and gamma-irradiation have similar effects on the in vitro quality of stored red cell components

BACKGROUND

Blood components are irradiated to inactivate lymphocytes to prevent transfusion-associated graft versus host disease. As there are little data regarding the effects of X-irradiation on red blood cell components (RBCs), the in vitro quality of stored red cells (standard, pediatric, washed, and intra-uterine transfusion [IUT]) following X- or gamma-irradiation was compared.

STUDY DESIGN AND METHODS

RBCs were pooled, split, and processed to produce standard (<14 days and < 5 days post-collection), pediatric (<5 days post-collection), washed (<14 days post-collection), or IUT RBCs (<5 days post-collection). Standard RBCs were either X- or gamma-irradiated (n = 10 pairs). A further 10 replicates were prepared by pooling and splitting three matched RBCs (X-, gamma-, and non-irradiated). All other RBCs were either X- or gamma-irradiated (n = 20 pairs). Red cell indices, hemolysis, potassium release, metabolism, microparticles, ATP, and 2,3-DPG were measured pre-irradiation and 6 h, 1, 2, 3, 7, 10, and 14 days post-irradiation, depending on the component type. Data were analyzed using two-way repeated measures ANOVA.

RESULTS

There were no significant differences in any in vitro quality measurements, with the exception of marginally higher potassium release in washed, IUT, and RBCs <5 days old (p < .0001) following X-irradiation. Both irradiation types increased generation of microvesicles, particularly in components that were older at the time of irradiation or stored for longer post-irradiation.

CONCLUSION

X- and gamma-irradiation have similar effects on the in vitro quality of RBCs, indicating that either technology is suitable for blood component irradiation.

Extracellular Vesicles and Thrombosis: Update on the Clinical and Experimental Evidence

Extracellular vesicles (EVs) compose a heterogenous group of membrane-derived particles, including exosomes, microvesicles and apoptotic bodies, which are released into the extracellular environment in response to proinflammatory or proapoptotic stimuli. From earlier studies suggesting that EV shedding constitutes a cellular clearance mechanism, it has become evident that EV formation, secretion and uptake represent important mechanisms of intercellular communication and exchange of a wide variety of molecules, with relevance in both physiological and pathological situations. The putative role of EVs in hemostasis and thrombosis is supported by clinical and experimental studies unraveling how these cell-derived structures affect clot formation (and resolution). From those studies, it has become clear that the prothrombotic effects of EVs are not restricted to the exposure of tissue factor (TF) and phosphatidylserines (PS), but also involve multiplication of procoagulant surfaces, cross-linking of different cellular players at the site of injury and transfer of activation signals to other cell types. Here, we summarize the existing and novel clinical and experimental evidence on the role and function of EVs during arterial and venous thrombus formation and how they may be used as biomarkers as well as therapeutic vectors.

Extracellular vesicles in the transfusion medicine field: The potential of proteomics

In transfusion centres, blood components are divided and stored following specific guidelines. The storage temperature and time vary among the blood cells but all of them release extracellular vesicles (EVs) under blood bank conditions. The clinical impact of such vesicles in blood components for transfusion is an object of debate, but should be considered and is being investigated. In this context, proteomics is an excellent tool to study the cargo and composition of EVs derived from red blood cells and platelets, since such vesicles are enriched in lipids and proteins. The development of quantitative mass spectrometry techniques and the evolution of bioinformatics have allowed the identification of novel EVs biomarkers for different diseases. In this context, the application of high coverage proteomic tools to the analysis of EVs in the transfusion medicine field would provide information about storage lesions and possible transfusion adverse reactions. This viewpoint article approaches the potential of proteomics to investigate the impact of EVs in blood bank transfusion components, especially red blood cells and platelets.

Expired But Not Yet Dead: Examining the Red Blood Cell Storage Lesion in Extended-Storage Whole Blood

ABSTRACT

Whole blood is a powerful resuscitation strategy for trauma patients but has a shorter shelf life than other blood products. The red blood cell storage lesion in whole blood has not previously been investigated beyond the standard storage period. In the present study, we hypothesized that erythrocytes in stored whole blood exhibit similar aspects of the red blood cell storage lesion and that transfusion of extended storage whole blood would not result in a more severe inflammatory response after hemorrhage in a murine model. To test this hypothesis, we stored low-titer, O-positive, whole blood units, and packed red blood cells (pRBCs) for up to 42 days, then determined aspects of the red blood cell storage lesion. Compared with standard storage pRBCs, whole blood demonstrated decreased microvesicle and free hemoglobin at 21 days of storage and no differences in osmotic fragility. At 42 days of storage, rotational thromboelastometry demonstrated that clotting time was decreased, alpha angle was increased, and clot formation time and maximum clot firmness similar in whole blood as compared with pRBCs with the addition of fresh frozen plasma. In a murine model, extended storage whole blood demonstrated decreased microvesicle formation, phosphatidylserine, and cell-free hemoglobin. After hemorrhage and resuscitation, TNF-a, IL-6, and IL-10 were decreased in mice resuscitated with whole blood. Red blood cell survival was similar at 24 h after transfusion. Taken together, these data suggest that red blood cells within whole blood stored for an extended period of time demonstrate similar or reduced accumulation of the red blood cell storage lesion as compared with pRBCs. Further examination of extended-storage whole blood is warranted.

Effects of storage and leukocyte reduction on the concentration and procoagulant activity of extracellular vesicles in canine packed red cells

OBJECTIVES

To characterize the size and procoagulant activity of extracellular vesicles (EV) that accumulate in canine packed red blood cells (pRBCs) over time and the effect of leukocyte reduction on these characteristics.

DESIGN

Prospective cohort study.

SETTING

Private small animal specialty referral hospital and university research laboratories.

ANIMALS

Ten healthy blood donor dogs.

INTERVENTIONS

Five pRBCs units were obtained according to standard protocols, and 5 were leukocyte-reduced prior to processing. Platelet-free supernatant from the pRBC units was collected on days 0, 10, 20, 32, and 42.

MEASUREMENTS AND MAIN RESULTS

Nanoparticle tracking analysis was performed to determine the size and concentration of EVs. Thrombin generation associated with phosphatidylserine-positive EVs was determined using a capture assay. Factor Xa generation associated with phosphatidylserine-positive EVs and tissue factor-positive EVs was measured in a subset of EVs isolated by centrifugation of the supernatant at 20,000 × g. R package nparLD and the Mann-Whitney U-test were used to determine the effect of duration of storage and the effect of leukocyte reduction, respectively. Small (mean < 125 nm) procoagulant EVs accumulated over time, with significant increases occurring on or after day 20 in both non-leukocyte reduced and leukocyte-reduced units. The procoagulant activity of the EVs was due to phosphatidylserine, not tissue factor. Increases in EV concentration and procoagulant activity occurred earlier in non-leukocyte reduced units. Extracellular vesicle accumulation and procoagulant activity were not decreased at any individual time point by leukocyte reduction.

CONCLUSIONS

Further studies characterizing and determining the clinical relevance of small procoagulant EVs in pRBCs are warranted.

Cell-Derived Microparticles in Blood Products from Blood Donors Deficient in Glucose-6-Phosphate Dehydrogenase

OBJECTIVE

To quantitate the microparticles (MPs) in whole blood and blood products obtained from blood donors who are deficient in glucose-6-phosphate dehydrogenase (G6PD).

METHODS

The current study analyzed whole blood and blood components prepared from 49 blood donors with G6PD deficiencies and 98 with G6PD-normal results. Packed red blood cells (PRBCs), platelet concentrate (PC), and plasma were prepared according to transfusion laboratory procedures. MP concentrations were determined using a flow cytometer.

RESULTS

Blood components prepared from donors with G6PD deficiency were characterized by higher red blood cell-derived MP (RMP) concentration in PRBCs (25,526 vs 18,738 particles/µL) but lower concentrations of platelet-derived MPs (PMPs; in whole blood and PC), leukocyte-derived MPs (LMP; in whole blood and plasma) and total MP (in PC), compared with those from donors with G6PD-normal test results.

CONCLUSIONS

These results suggest that differences in G6PD status may account for variation in RMP levels during processing.

Extracellular Vesicles in Autologous Cell Salvaged Blood in Orthopedic Surgery

(1) Background: Cell salvage is highly recommended in orthopedic surgery to avoid allogeneic transfusions. Preparational steps during cell salvage may induce extracellular vesicle (EV) formation with potential thrombogenic activity. The purpose of our study was to assess the appearance of EVs at retransfusion. (2) Methods: After ethics committee approval and informed consent, blood was withdrawn from the autotransfusion system (Xtra, Sorin, Germany) of 23 patients undergoing joint arthroplasty. EVs were assessed by flow cytometry in two times centrifugated samples. EVs were stained with specific antibodies against cellular origins from platelets (CD41), myeloid cells (CD15), monocytes (CD14), and erythrocytes (CD235a). The measured events/µL in the flow cytometer were corrected to the number of EVs in the retransfusate. (3) Results: We measured low event rates of EVs from platelets and myeloid origin (<1 event/µL) and from monocytic origin (<2 events/µL). Mean event rates of 17,042 events/µL (range 12–81,164 events/µL) were found for EVs from red blood cells. (4) Conclusion: Retransfusate contains negligible amounts of potentially thrombogenic EVs from platelet and monocytic origin. Frequent EVs from erythrocytes may indicate red blood cell destruction and/or activation during autologous cell salvage. Further research is needed to investigate the clinical relevance of EVs from salvaged red blood cells.

Transfusion-associated circulatory overload and high blood pressure: A multicentre retrospective study in Japan

BACKGROUND

Transfusion-associated circulatory overload (TACO) is an adverse reaction associated with a high risk of mortality. The actual incidence of TACO and hypertension associated with transfusion in Japan is unknown.

METHODS

A multicentre retrospective observational study was conducted across 23 institutions during the 1-year period of 2016. Patients were included if they developed TACO or their blood pressure (either systolic or diastolic) increased by at least 30 mmHg during the transfusion. TACO was confirmed by the primary physicians and transfusion medicine teams and recorded in the data on passive surveillance, and additional data were extracted from electronic medical records.

RESULTS

In our patient cohort of 31 384 patients who underwent transfusion, the incidence of TACO and hypertension was 0·03% and 0·2%, respectively. However, 43% of the participating institutions didn't report any cases. When comparing risk factors between the TACO and hypertension groups, there were significant differences in comorbidities, such as abnormal findings on chest x-ray. Significant differences between the two groups were observed post-transfusion pulse rate, body temperature and oxygen saturation (P < 0·01). In the group of patients with hypertension, the level of BNP increased significantly after transfusion in 45% (5/11) of the patients. We identified 4 patients in the hypertension group who met the new ISBT's TACO criteria.

CONCLUSION

Our study suggests that more attention should be given to TACO in Japan, particularly in terms of improving surveillance systems. For the early diagnosis of TACO, it is crucial to carefully monitor vital signs including blood pressure.

Extracellular Vesicles from Red Blood Cells and Their Evolving Roles in Health, Coagulopathy and Therapy

Red blood cells (RBCs) release extracellular vesicles (EVs) including both endosome-derived exosomes and plasma-membrane-derived microvesicles (MVs). RBC-derived EVs (RBCEVs) are secreted during erythropoiesis, physiological cellular aging, disease conditions, and in response to environmental stressors. RBCEVs are enriched in various bioactive molecules that facilitate cell to cell communication and can act as markers of disease. RBCEVs contribute towards physiological adaptive responses to hypoxia as well as pathophysiological progression of diabetes and genetic non-malignant hematologic disease. Moreover, a considerable number of studies focus on the role of EVs from stored RBCs and have evaluated post transfusion consequences associated with their exposure. Interestingly, RBCEVs are important contributors toward coagulopathy in hematological disorders, thus representing a unique evolving area of study that can provide insights into molecular mechanisms that contribute toward dysregulated hemostasis associated with several disease conditions. Relevant work to this point provides a foundation on which to build further studies focused on unraveling the potential roles of RBCEVs in health and disease. In this review, we provide an analysis and summary of RBCEVs biogenesis, composition, and their biological function with a special emphasis on RBCEV pathophysiological contribution to coagulopathy. Further, we consider potential therapeutic applications of RBCEVs.

Washing packed red blood cells decreases red blood cell storage lesion formation

BACKGROUND

Transfusion of blood products is the ideal resuscitative strategy after hemorrhage. Unfortunately, older packed red blood cells have been associated with increased morbidity and mortality after massive transfusion. These packed red blood cells accumulate biochemical and structural changes known as the red blood cell storage lesions. The effect of washing on the formation of red blood cell storage lesions is unknown. We hypothesized that washing packed red blood cells during storage would decrease the development of the red blood cell storage lesions.

METHODS

Blood from 8- to 10-week-old male mice donors was stored as packed red blood cells for 14 days. A subset of packed red blood cells were washed with phosphate-buffered saline on storage day 7 and resuspended in AS-1 solution for an additional 7 days as washed packed red blood cells. Subsequently, the packed red blood cells were analyzed for microvesicle release, band-3 erythrocyte membrane integrity protein (Band-3), expression of phosphatidylserine, cell viability (calcein), accumulation of cell-free hemoglobin, and osmotic fragility.

RESULTS

In the washed packed red blood cells group, there was less microvesicle accumulation, greater Band-3 expression, less phosphatidylserine expression, a decrease in cell-free hemoglobin accumulation, and a decrease in osmotic fragility, but no differences in red blood cells viability.

CONCLUSION

Washing packed red blood cells during storage decreases the accumulation of red blood cell storage lesions. This strategy may lessen the sequelae associated with transfusion of older packed red blood cells.

Shock Severity Modifies Associations Between RBC Transfusion in the First 48 Hours of Sepsis Onset and the Duration of Organ Dysfunction in Critically Ill Septic Children

OBJECTIVE

To test the hypothesis that early RBC transfusion is associated with duration of organ dysfunction in critically ill septic children.

DESIGN

Secondary analysis of a single-center prospective observational study. Multivariable negative binomial regression was used to determine relationships between RBC transfusion within 48 hours of sepsis onset and number of days in 14 with organ dysfunction, or with multiple organ dysfunction syndrome.

SETTING

A PICU at a quaternary care children's hospital.

PATIENTS

Children less than 18 years old with severe sepsis/septic shock by consensus criteria were included. Patients with RBC transfusion prior to sepsis onset and those on extracorporeal membrane oxygenation support within 48 hours of sepsis onset were excluded.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Ninety-four patients were included. Median age was 6 years (0-13 yr); 61% were male. Seventy-eight percentage had septic shock, and 41 (44%) were transfused RBC within 48 hours of sepsis onset (early RBC transfusion). On multivariable analyses, early RBC transfusion was independently associated with 44% greater organ dysfunction days (adjusted relative risk, 1.44 [1.04-2.]; p = 0.03), although risk differed by severity of illness (interaction p = 0.004) and by shock severity (interaction p = 0.04 for Vasoactive Inotrope Score and 0.03 for shock index). Relative risks for multiple organ dysfunction syndrome days varied by shock severity (interaction p = 0.008 for Vasoactive Inotrope Score and 0.01 for shock index). Risks associated with early RBC transfusion were highest for the children with the lowest shock severities.

CONCLUSIONS

In agreement with previous studies, early RBC transfusion was independently associated with longer duration of organ dysfunction. Ours is among the first studies to document different transfusion-associated risks based on clinically available measures of shock severity, demonstrating greater transfusion-associated risks in children with less severe shock. Larger multicenter studies to verify these interaction effects are essential to plan much-needed RBC transfusion trials for critically ill septic children.

The role of extracellular vesicles from stored RBC units in B lymphocyte survival and plasma cell differentiation

Extracellular vesicles (EVs) are small, double-membrane vesicles derived from erythrocytes, leukocytes, platelets, and cells of multiple tissues under physiologic or pathologic conditions. The role of EVs in stored RBC units is of great interest with respect to transfusion-related immunomodulation. The current study focuses on the quantity of EVs isolated from stored RBC units and their action on B cell-mediated immune responses. The in vitro experiment demonstrated that EVs exhibited a negative role in B cell survival, plasmacytic differentiation, and class switch recombination under LPS stimulation. Furthermore, LPS-induced antibody production was significantly decreased after EVs injection in vivo. Biochemical analysis revealed that EVs hampered the expression of Blimp-1 and IRF4 and the activation of NF-κB pathway in LPS-primed B cells. Overall, these data imply a vital role for EVs isolated from RBC units in B cell-mediated immune responses.

Red-blood-cell manufacturing methods and storage solutions differentially induce pulmonary cell activation

Background and Objectives

Red‐blood‐cell (RBC) transfusion is associated with lung injury, which is further exacerbated by mechanical ventilation. Manufacturing methods of blood products differ globally and may play a role in the induction of pulmonary cell activation through alteration of the immunomodulatory property of the products. Here, the effect of different manufacturing methods on pulmonary cell activation was investigated in an in vitro model of mechanical ventilation.

Materials and Methods

Pulmonary type II cells were incubated with supernatant from fresh and old RBC products obtained via whole blood filtration (WBF), red cell filtration (RCF), apheresis‐derived (AD) or whole blood‐derived (WBD) methods. Lung cells were subjected to 25% stretch for 24 h. Controls were non‐stretched or non‐incubated cells.

Results

Fresh but not old AD products and WBF products induce lung cell production of pro‐inflammatory cytokines and chemokines, which was not observed with WBD or RCF products. Effects were associated with an increased amount of platelet‐derived vesicles and an increased thrombin‐generating capacity. Mechanical stretching of lung cells induced more severe cell injury compared to un‐stretched controls, including alterations in the cytoskeleton, which was further augmented by incubation with AD products. In all read‐out parameters, RCF products seemed to induce less injury compared to the other products.

Conclusions

Our findings show that manufacturing methods of RBC products impact pulmonary cell activation, which may be mediated by the generation of vesicles in the product. We suggest RBC manufacturing method may be an important factor in understanding the association between RBC transfusion and lung injury.

Quantitation of Cell-Derived Microparticles in Blood Products and Its Potential Applications in Transfusion Laboratories

Cell-derived microparticles (MPs) are small fragments released from various cells when they are activated or undergo apoptosis. In the field of transfusion medicine, a number of studies have documented increased levels of MPs in blood products, which have been associated with multiple factors, including donor variability, blood component processing, and storage. In addition, transfusions that contain high levels of MPs are linked to posttransfusion complications. Considering the clinical importance of MP levels, transfusion laboratories should routinely screen blood products for them. However, this practice is not yet applied routinely, perhaps in part because of a lack of understanding of how to apply MP data to transfusion medicine. We describe the methods used to quantitate MPs in blood components and discuss the application of these quantitative data in routine transfusion laboratories in order to manage quality, improve the outcomes of transfusions, and minimize their complications.

Contrasting effects of stored allogeneic red blood cells and their supernatants on permeability and inflammatory responses in human pulmonary endothelial cells

Transfusion of red blood cells (RBCs) is a common life-saving clinical practice in severely anemic or hemorrhagic patients; however, it may result in serious pathological complications such as transfusion-related acute lung injury. The factors mediating the deleterious effects of RBC transfusion remain unclear. In this study, we tested the effects of washed long-term (RBC-O; >28 days) versus short-term (RBC-F; <14 days) stored RBCs and their supernatants on lung endothelial (EC) permeability under control and inflammatory conditions. RBCs enhanced basal EC barrier function as evidenced by an increase in transendothelial electrical resistance and decrease in permeability for macromolecules. RBCs also attenuated EC hyperpermeability and suppressed secretion of EC adhesion molecule ICAM-1 and proinflammatory cytokine IL-8 in response to LPS or TNF-α. In both settings, RBC-F had slightly higher barrier protective effects as compared with RBC-O. In contrast, supernatants from both RBC-F and RBC-O disrupted the EC barrier. The early phase of EC permeability response caused by RBC supernatants was partially suppressed by antioxidant N-acetyl cysteine and inhibitor of Src kinase family PP2, while addition of heme blocker and inhibition of NOD-like receptor family pyrin domain containing protein 3 (NLRP3), stress MAP kinases, receptor for advanced glycation end-products (RAGE), or Toll-like receptor-4 (TLR4) signaling were without effect. Morphological analysis revealed that RBC supernatants increased LPS- and TNF-α-induced breakdown of intercellular junctions and formation of paracellular gaps. RBC supernatants augmented LPS- and TNF-α-induced EC inflammation reflected by increased production of IL-6, IL-8, and soluble ICAM-1. These findings demonstrate the deleterious effects of RBC supernatants on EC function, which may have a major impact in pathological consequences associated with RBC transfusion.

Volume incompliance and transfusion are essential for transfusion-associated circulatory overload: a novel animal model

BACKGROUND

Transfusion‐associated circulatory overload (TACO) is the predominant complication of transfusion resulting in death. The pathophysiology is poorly understood, but inability to manage volume is associated with TACO, and observational data suggest it is different from simple cardiac overload due to fluids. We developed a two‐hit TACO animal model to assess the role of volume incompliance (“first‐hit”) and studied whether volume overload (“second‐hit”) by red blood cell (RBC) transfusion is different compared to fluids (Ringer's lactate [RL]).

MATERIALS AND METHODS

Male adult Lewis rats were stratified into a control group (no intervention) or a first hit: either myocardial infarction (MI) or acute kidney injury (AKI). Animals were randomized to a second hit of either RBC transfusion or an equal volume of RL. A clinically relevant difference was defined as an increase in left ventricular end‐diastolic pressure (ΔLVEDP) of +4.0 mm Hg between the RBC and RL groups.

RESULTS

In control animals (without first hit) LVEDP was not different between infusion groups (Δ + 1.6 mm Hg). LVEDP increased significantly more after RBCs compared to RL in animals with MI (Δ7.4 mm Hg) and AKI (Δ + 5.4 mm Hg), respectively. Volume‐incompliant rats matched clinical TACO criteria in 92% of transfused versus 25% of RL‐infused animals, with a greater increase in heart rate and significantly higher blood pressure.

CONCLUSION

To our knowledge, this is the first animal model for TACO, showing that a combination of volume incompliance and transfusion is essential for development of circulatory overload. This model allows for further testing of mechanistic factors as well as therapeutic approaches.

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.

Perioperative blood transfusions following hepatic lobectomy: A national analysis of academic medical centers in the modern era

BACKGROUND

The purpose of the study was to characterize the prevalence and impact of perioperative blood use for patients undergoing hepatic lobectomy at academic medical centers.

METHODS

The University HealthSystem Consortium (UHC) database was queried for hepatic lobectomies performed between 2011 and 2014 (n = 6476). Patients were grouped according to transfusion requirements into high (>5 units, 7%), medium (2-5 units, 6%), low (1 unit, 8%), and none (0 units, 79%) during hospital stay for comparison of outcomes.

RESULTS

Over 20% of patients undergoing hepatic lobectomy received blood perioperatively, of which 35% required more than 5 units. Patients with high transfusion requirements had increased severity of illness (p < 0.01). High transfusion requirements correlated with increased readmission rates (23.4% vs. 19.2% vs. 16.6% vs. 13.5%), total direct costs ($31,982 vs. $20,859 vs. $19,457 vs. $16,934), length of stay (9 days vs. 8 vs. 7 vs. 6), and in-hospital mortality (10.8% vs. 2.0% vs. 0.9% vs. 2.0%) compared to medium, low, and no transfusion amounts (all p < 0.01). Neither center nor surgeon volume were associated with transfusion use.

CONCLUSION

High transfusion requirements after hepatic lobectomy in the United States are associated with worse perioperative quality measures, but may not be influenced by center or surgeon volume.

Preclinical Evaluation of Safety and Biodistribution of Red Cell Microparticles: A Novel Hemostatic Agent

BACKGROUND

Uncontrollable bleeding is a major cause of mortality and morbidity worldwide. Effective hemostatic agents are urgently needed. Red cell microparticles (RMPs) are a highly promising hemostatic agent. This study evaluated the safety profile of RMPs preliminary to clinical trial.

METHODS AND RESULTS

RMPs were prepared from type O+ human red blood cell by high-pressure extrusion. Male rats were treated with RMPs either a 1 × bolus, or 4 × or 20 × administered over 60 minutes. The vehicle-treated group was used as a control. Effects on physiological parameters were evaluated; namely, blood pressure, body and head temperature, hematocrit, and blood gases. We did not observe any adverse effects of RMPs on these physiological parameters. In addition, brain, heart, and lungs of rats treated with 4 × dose (bolus followed by infusion over 60 minutes) or vehicle were examined histologically for signs of thrombosis or other indications of toxicity. No thrombosis or indications of toxicity in brain, heart, or lungs were observed. Studies revealed that RMPs were distributed mainly in liver, spleen, and lymph nodes, and were potentially excreted through the kidneys.

CONCLUSIONS

Our study indicates that RMP administration appears not to have any negative impact on the parameters studied and did not produce thrombosis in heart, brain, and lungs. However, more detailed long-term studies confirming the safety of RMP as a hemostatic agent are warranted.

Extracellular Vesicles in Red Blood Cell Concentrates: An Overview

Red blood cell (RBC) concentrates may be stored for up to 42 days before transfusion to a patient. During storage extracellular vesicles (EVs) develop and can be detected in significant amounts in RBC concentrates. The concentration of EVs is affected by component preparation methods, storage solutions, and inter-donor variation. Laboratory investigations have focused on the effect of EVs on in vitro assays of thrombin generation and immune responses. Assays for EVs in RBC concentrates are not standardized. The aims of this review are to describe the factors that determine the presence of erythrocyte-EVs in RBC concentrates, the current techniques used to characterize them, and the potential role of EV analysis as a quality control maker for RBC storage.

Red blood cells: the forgotten player in hemostasis and thrombosis

New evidence has stirred up a long-standing but undeservedly forgotten interest in the role of erythrocytes, or red blood cells (RBCs), in blood clotting and its disorders. This review summarizes the most recent research that describes the involvement of RBCs in hemostasis and thrombosis. There are both quantitative and qualitative changes in RBCs that affect bleeding and thrombosis, as well as interactions of RBCs with cellular and molecular components of the hemostatic system. The changes in RBCs that affect hemostasis and thrombosis include RBC counts or hematocrit (modulating blood rheology through viscosity) and qualitative changes, such as deformability, aggregation, expression of adhesive proteins and phosphatidylserine, release of extracellular microvesicles, and hemolysis. The pathogenic mechanisms implicated in thrombotic and hemorrhagic risk include variable adherence of RBCs to the vessel wall, which depends on the functional state of RBCs and/or endothelium, modulation of platelet reactivity and platelet margination, alterations of fibrin structure and reduced susceptibility to fibrinolysis, modulation of nitric oxide availability, and the levels of von Willebrand factor and factor VIII in blood related to the ABO blood group system. RBCs are involved in platelet-driven contraction of clots and thrombi that results in formation of a tightly packed array of polyhedral erythrocytes, or polyhedrocytes, which comprises a nearly impermeable barrier that is important for hemostasis and wound healing. The revisited notion of the importance of RBCs is largely based on clinical and experimental associations between RBCs and thrombosis or bleeding, implying that RBCs are a prospective therapeutic target in hemostatic and thrombotic disorders.

Application of Extracellular Vesicles Proteomics to Cardiovascular Disease: Guidelines, Data Analysis, and Future Perspectives

Extracellular vesicles (EVs) are a heterogeneous population of vesicles composed of a lipid bilayer that carry a large repertoire of molecules including proteins, lipids, and nucleic acids. In this review, some guidelines for plasma-derived EVs isolation, characterization, and proteomic analysis, and the application of the above to cardiovascular disease (CVD) studies are provided. For EVs analysis, blood samples should be collected using a 21-gauge needle, preferably in citrate tubes, and plasma stored for up to 1 year at -80°, using a single freeze-thaw cycle. For proteomic applications, differential centrifugation (including ultracentrifugation steps) is a good option for EVs isolation. EVs characterization is done by transmission electron microscopy, particle enumeration techniques (nanoparticle-tracking analysis, dynamic light scattering), and flow cytometry. Regarding the proteomics strategy, a label-free and gel-free quantitative method is a good choice due to its accuracy and because it minimizes the amount of sample required for clinical applications. Besides the above, main EVs proteomic findings in cardiovascular-related diseases are presented and analyzed in this review, paying especial attention to overlapping results between studies. The latter might offer new insights into the clinical relevance and potential of novel EVs biomarkers identified to date in the context of CVD.

Red blood cell transfusion and its alternatives in oncologic surgery-A critical evaluation

Although blood transfusions have been used for more than 100 years and their potential to save lives is indisputable, there is still limited data on medium- and long-term outcomes after hemotherapy. Until recently, red blood cell transfusions represented the most commonly employed treatment for cancer anemia. As transfusions have been related to worse patient outcome in oncologic surgery, preventive strategies and alternative treatment approaches in the perioperative setting are warranted. This review aims to evaluate the evidence concerning the impact of transfusion on the course of malignant diseases with a focus on oncologic surgery and to provide a bundle of measures to improve patient care. The perioperative period is pivotal in determining long-term cancer outcome. An increasingly recognized area for improvement during this highly sensitive period is the treatment of anemia for three main reasons: Firstly, anemia has been recognized as an independent predictor of poor prognosis in cancer patients. Secondly, anemia is largely undertreated. Thirdly and probably most importantly, anemia therapy relied and often still relies heavily on red blood cell (RBC) transfusions, which may be an often suboptimal stopgap treatment. Perioperative RBC transfusions should be kept to a minimum due to growing concerns regarding the associated risks, which this review tries to clarify by providing an update of recent literature. This review furthermore discusses treatments for anemia and provides best-practice approaches to improve perioperative management of oncology patients undergoing surgery.

Screening of red blood cells for extracellular vesicle content as a product quality indicator

BACKGROUND

The controversy around the quality and clinical impact of stored and differentially manufactured red cell concentrates (RCCs) from different donor groups is ongoing. Current studies are limited by the lack of quality measures suitable for routine screening of RCCs. As extracellular vesicles (EVs) are markers of cellular activation or degradation, this study investigated the utility of EV screening to characterize the effects of RBCs production methods and storage.

STUDY DESIGN AND METHODS

RCCs were prepared by whole blood filtration or red blood cell (RBC) filtration methods, centrifuged to prepare a supernatant, and tested for EV content (dynamic light scattering or tunable resistive pulse-sensing techniques), hemolysis, ATP, and RBC deformability on Days 7, 21, and 42 of storage. To simulate nondestructive quality control (QC) testing, 1 RBC unit was tested in parallel with six 10-mL aliquots that were stored in small-volume containers.

RESULTS

EV content showed a linear increase with storage time (p < 0.001) and correlated with supernatant hemoglobin and inversely with ATP or RBC deformability. The method of component manufacturing influenced the characteristics of the EVs during storage. A strong correlation between both EV testing methods' measure of total EV was observed. EV content in the six aliquots were consistent at each time point but statistically higher than in the original RCCs on and after 21 days of storage.

CONCLUSIONS

EV content correlates with measures of hemolysis and other RBC quality indicators and could be implemented as a routine screening tool for nondestructive QC testing of RCCs.