Microparticles from aged packed red blood cell units stimulate pulmonary microthrombus formation via P-selectin

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.

Microvesicles from stored red blood cells induce P-selectin and von Willebrand factor release from endothelial cells via a protein kinase C-dependent mechanism

INTRODUCTION

The use of packed red blood cells (pRBCs) for resuscitation is limited by the red blood cell storage lesion, a series of biochemical and physiological changes that occur during the storage and aging of blood. Microvesicles (MVs) shed from pRBCs during this process are one component of the red blood cell storage lesion and lead to acute lung injury and pulmonary vascular microthrombi. We hypothesized that MVs from stored pRBCs lead to the release of P-selectin and von Willebrand factor (vWF) from endothelial cells and that this mechanism is mediated via activation of protein kinase C (PKC) or protein kinase A (PKA).

METHODS

Leukoreduced, platelet-poor murine pRBCs were isolated from C57BL/6 8-12 week-old male mice via cardiac puncture, prepared via centrifugation using a Ficoll gradient, and stored for up to 14 days, the equivalent of 42 days of storage in humans. MVs were isolated from the stored pRBC units via sequential high-speed centrifugation. Murine lung endothelial cells (MLECs) were cultured and grown to confluence, then treated with MVs and either calphostin C, a PKC inhibitor (10 μg/mL), or PKI 14-22 amide, a PKA inhibitor (10 μM). The supernatant was collected after 1 h. P-selectin and vWF A2 concentrations were quantified via ELISA. Immunofluorescent staining for vWF was performed on MLECs. Statistical analysis was performed via unpaired t-test or ANOVA as indicated and reported as mean ± SD. Concentration is reported as pg/mL.

RESULTS

MLECs treated with MVs isolated from stored pRBCs demonstrated increased release of P-selectin and vWF A2 in a dose-dependent fashion. MLECs treated with MVs prepared from stored as compared to fresh pRBCs demonstrated increased release of P-selectin (3751 ± 726 vs 359 ± 64 pg/mL, p < 0.0001) and vWF A2 (3141 ± 355 vs 977 ± 75 pg/mL, p < 0.0001) with increasing duration of storage. The treatment of MVs with calphostin C decreased the amount of P-selectin (1471 ± 444 vs 3751 ± 726 pg/mL, p < 0.0001) and VWF A2 (2401 ± 289 vs 3141 ± 355 pg/mL, p = 0.0017) released into the supernatant by MLECs compared to MVs alone. The treatment of MVs with PKI 14-22 increased the amount of P-selectin released compared to MVs alone (1999 ± 67 vs 1601 ± 135 pg/mL, p = 0.0018).

CONCLUSIONS

MVs from stored pRBCs stimulate the release of P-selectin and VWF A2 from endothelial cells. The effect of MVs increases with both dose of MVs and age of stored pRBCs from which they are formed. This mechanism is dependent on activation of PKC and inhibition of this enzyme represents a potentially significant strategy to modulate the inflammatory response to resuscitation with stored pRBCs.

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.

Transcriptomic analysis of mRNAs in human whole blood identified age-specific changes in healthy individuals

Older age is one of the most important shared risk factors for multiple chronic diseases, increasing the medical burden to contemporary societies. Current research focuses on identifying aging biomarkers to predict aging trajectories and developing interventions aimed at preventing and delaying the progression of multimorbidity with aging. Here, a transcriptomic changes analysis of whole blood genes with age was conducted. The age-related whole blood gene-expression profiling datasets were downloaded from the Gene Expression Omnibus (GEO) database. We screened the differentially expressed genes (DEGs) between healthy young and old individuals and performed functional enrichment analysis. Cytoscape with Cytohubba and MCODE was used to perform an interaction network of DEGs and identify hub genes. In addition, ROC curves and correlation analysis were used to evaluate the accuracy of hub genes. In total, we identified 29 DEGs between young and old samples that were enriched mainly in immunoglobulin binding and complex, humoral immune response, and immune response-activating signaling pathways. In combination with the PPI network and topological analysis, 4 hub genes (IGLL5, Jchain, POU2AF1, and Bach2) were identified. Pearson analysis showed that the expression changes of these hub genes were highly correlated with age. Among them, 3 hub genes (IGLL5, POU2AF1, and Bach2) were identified with good accuracy (AUC score > 0.7), indicating that these genes were the best indicators of age. Together, our results provided potential biomarkers IGLL5, POU2AF1, and Bach2 to identify individuals at high early risk of age-related disease to be targeted for early interventions and contribute to understanding the molecular mechanisms in the progression of aging.

Changes in hemoglobin oxidation and band 3 during blood storage impact oxygen sensing and mitochondrial bioenergetic pathways in the human pulmonary arterial endothelial cell model

Red blood cells (RBCs) undergo metabolic, oxidative, and physiological changes during storage, collectively described as the "storage lesion." The impact of storage on oxygen homeostasis, following transfusion, is not fully understood. We show that RBC storage induces changes in oxygen binding that were linked to changes in oxygen sensing (hypoxia-inducible factor, HIF-1α) mechanisms and mitochondrial respiration in human pulmonary arterial endothelial cells (HPAECs). A decrease in oxygen affinity (P50) to approximately 20 from 30 mmHg was seen at the first week but remained unchanged for up to 42 days. This led to the suppression of HIF-1α in the first 3 weeks due to limited oxygen supplies by RBCs. Furthermore, membrane oxidative damage, band 3 alterations, and subsequent microparticle (MP) formation were also noted. Mass spectrometric analysis revealed the upregulation of transitional endoplasmic reticulum ATPase, essential for clearing ROS-damaged membrane proteins and the protein DDI1 homolog, a proteasomal shuttle chaperone. Band 3 complex proteins and superoxide dismutase were among the downregulated proteins. Mitochondrial oxygen consumption rates measured in HPAECs incubated with RBC-derived MPs (14-day and 42-day) showed a rise in maximal respiration. Intervention strategies that target intracellular hemoglobin (Hb)'s redox transitions and membrane changes may lead to the reestablishment of oxygen homeostasis in old RBCs.

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.

High expression of P-selectin induces neutrophil extracellular traps via the PSGL-1/Syk/Ca2+/PAD4 pathway to exacerbate acute pancreatitis

Background

Excessive neutrophil extracellular traps (NETs) is involved in the progression of acute pancreatitis (AP) but the mechanisms controlling NETs formation in AP are not fully understood. Therefore, our study sought to investigate the mechanism of the highly expressed P-selectin stimulating the formation of NETs in AP.

Methods

NETs formation was detected by flow cytometry, immunofluorescence staining, and cf-DNA and MPO-DNA complexes were measured as biomarkers of NETs formation. Neutrophils treated with P-selectin and pharmacological inhibitors were examined by western blot, immunofluorescence staining and flow cytometry. Mouse model of AP was established by caerulein and the effect of inhibiting P-selectin by PSI-697 on the level of NETs and PAD4 in pancreatic tissue was observed. The severity of AP was evaluated by histopathological score and the detection of serum amylase and lipase.

Results

Patients with AP had elevated levels of NETs and P-selectin compared with healthy volunteers. Stimulation of P-selectin up-regulated the expression of PSGL-1, increased the phosphorylation of Syk, mediated intracellular calcium signal and led to the activation and expression of PAD4, which modulated NETs formation in neutrophils. Pretreament with PSI-697 blunted NETs formation and PAD4 expression in the pancreatic tissue, and ameliorated the severity of AP in mice.

Conclusion

Taken together, these results suggest that P-selectin induces NETs through PSGL-1 and its downstream Syk/Ca2+/PAD4 signaling pathway, and that targeting this pathway might be a promising strategy for the treatment of AP.

LncRNA MSTRG.22719.16 mediates the reduction of enoxaparin sodium high-viscosity bone cement-induced thrombosis by targeting the ocu-miR-326-5p/CD40 axis

OBJECTIVE

Polymethylmethacrylate (PMMA) bone cement promotes the development of local thrombi. Our study found that a novel material, ES-PMMA bone cement, can reduce local thrombosis. We used a simple and reproducible animal model to confirm the reduction in local thrombosis and explored the associated molecular mechanism.

METHODS

New Zealand rabbits, which were used to model thrombosis using extracorporeal carotid artery shunts, were divided into the following two groups, with 3 rabbits in each group: the PMMA bone cement group and the ES-PMMA bone cement group. Four hours after modelling, experimental samples, including thrombotic and vascular tissues, were collected. Thrombotic samples from the PMMA group and ES-PMMA group were subjected to lncRNA sequencing, and a lncRNA microarray was used to screen the differentially expressed lncRNAs. The expression of thrombomodulin in endothelial cells was quantified in vascular tissue samples. Differences in the lncRNA expression profiles between the thrombotic samples of the PMMA group and ES-PMMA group were assessed by base-to-base alignment in the intergenic regions of genomes. The lncRNA-miRNA-mRNA competitive endogenous RNA (ceRNA) network was established in light of ceRNA theory. Thrombosis was observed in the PMMA group and ES-PMMA group.

RESULTS

The thrombotic weight was 0.00706 ± 0.00136 g/cm in the PMMA group and 0.00551 ± 0.00115 g/cm in the ES-PMMA group. Quantitative real-time polymerase chain reaction (RT-q-CR) and Western blotting revealed that the expression of CD40, which can regulate thrombosis in vascular endothelial cells, was significantly lower in the ES-PMMA group than in the PMMA group. High-throughput sequencing was used to identify 111 lncRNAs with lower expression in the ES-PMMA group than in the PMMA group. Through bioinformatics investigation, lncRNA MSTRG22719.16/ocu-miR-326-5p/CD40 binding sites were selected. Fluorescent in situ RNA hybridization (FISH) was performed to verify the lower expression of lncRNA MSTRG.22719.16 in vascular tissues from the ES-PMMA group. A dual-luciferase reporter gene assay was applied to verify that ocu-miR-326-5p binds the CD40 3'-UTR and targets lncRNA MSTRG.22719.16.

CONCLUSION

Compared with PMMA bone cement, ES-PMMA bone cement can reduce thrombosis through the lncRNA MSTRG.22719.16/ocu-miR-326-5p/CD40 axis.

Red blood cell transfusion is associated with an increased risk of splanchnic vein thrombosis in patients with cirrhosis

BACKGROUND

Haemorrhage and coagulation disorders are common complications in cirrhotic patients, which cause blood products transfusion, and mounting evidence suggested that red blood cells (RBCs) were associated with pathologic thrombosis and RBC transfusion increased the risk of venous thromboembolism (VTE).

AIMS

The aim of the study was to investigate the association of RBC transfusion with splanchnic vein thrombosis (SVT) in cirrhotic patients.

MATERIALS & METHODS

We retrospectively reviewed patients with cirrhosis admitted in the Hunan Provincial People's Hospital between January 2010 and September 2020. Demographic data, the development of SVT, blood transfusion product type and RBC transfusion dose were collected. Multivariate logistic regression analyses and propensity matching analysis (PSM) were performed to identify the association between RBC transfusion and development of SVT.

RESULTS

A total of 4479 patients with cirrhosis were enrolled in the study. SVT occurred in 48 (12.4%) cirrhotic patients in RBC transfusion group, and 233 (5.7%) cirrhotic patients in non-RBC transfusion group. RBC transfusion was significantly associated with an increased risk of SVT (unadjusted odds ratio [OR] 2.345, 95% confidence interval [CI] 1.686-3.262, p < 0.001). Notably, this association remained robust after PSM, and the volume of RBC transfusion was associated with SVT in a dose-dependent manner.

CONCLUSION

This study suggested that RBC transfusion was associated with an increased risk of SVT in cirrhotic patients. High quality clinical study will be needed to further validate the association between RBC transfusion and SVT.

The Association of Glucose Control with Circulating Levels of Red Blood Cell-Derived Vesicles in Type 2 Diabetes Mellitus Patients with Atrial Fibrillation

Hyperglycemia is a trigger for structural alteration of red blood cells (RBCs) and their ability to release extracellular vesicles (EVs). The aim of the study was to elucidate whether glucose control in T2DM patients with concomitant HF and AF affects a circulating number of RBC-derived EVs. We prospectively included 417 T2DM patients with HF, 51 of them had atrial fibrillation and 25 healthy volunteers and 30 T2DM non-HF individuals. Clinical assessment, echocardiography examination and biomarker measures were performed at the baseline of the study. RBC-derived EVs were determined as CD235a+ PS+ particles by flow cytometry. NT-proBNP levels were measured by ELISA. AF patients with glycosylated hemoglobin (HbA1c) < 6.9% had lower levels of CD235a+ PS+ RBC-derived vesicles than those with HbA1c ≥ 7.0%. There were no significant differences in number of CD235a+ PS+ RBC-derived vesicles between patients in entire cohort and in non-AF sub-cohort with HbA1c < 6.9% and HbA1c ≥ 7.0%, respectively. Multivariate linear regression yielded that CD235a+ PS+ RBC-derived vesicles ≥ 545 particles in µL (OR = 1.06; 95% CI = 1.01−1.11, p = 0.044) independently predicted HbA1c ≥ 7.0%. Elevated levels of CD235a+ PS+ RBC-derived EVs independently predicted poor glycaemia control in T2DM patients with HF and AF.

The in vitro red blood cell microvesiculation exerts procoagulant activity of blood cell storage in Southeast Asian ovalocytosis

Southeast Asian ovalocytosis (SAO) is characterized by the misfolding of band 3 protein in red blood cells (RBC). The abnormal structure of the band 3 protein results in dysmorphic RBC and related functions. Previous data showed that in vitro storage under hypothermic conditions alters band 3 protein structure and function. Microvesiculation includes shedding of RBC membranes, called RBC-derived microparticles/extracellular vesicles (RMP/EVs), and storage lesions. Unfortunately, there is no evidence of RBC microvesiculation under in vitro storage conditions in heterozygous SAO individuals. This study determined the generation of REVs and procoagulant activity during the storage of SAO blood samples in southern Thailand. Venous blood was collected from eight SAO and seven healthy individuals, preserved in citrate phosphate dextrose-adenine 1 (CPDA-1) at 4 °C for 35 days. The absolute numbers of REVs and PS-expressing RBCs were analyzed using flow cytometry. The procoagulant activity of the produced extracellular vesicles was determined by a clotting time assay. The results showed a significant increase in the number of REVs and PS-expressing RBCs in the SAO blood samples. Significantly correlated PS externalization and procoagulant activity were observed in the SAO blood samples. These lines of evidence indicate that the abnormality of the Band 3 protein is possibly involved in aberrant microvesiculation, exerting procoagulant activity in vitro. Increased pools of REV production and abnormal storage lesions in SAO blood samples should be a concern. Notably, the mechanisms underlying membrane vesiculation depend on the extent of blood cell storage under hypothermic conditions.

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.

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.

Size Distribution of Microparticles: A New Parameter to Predict Acute Lung Injury After Cardiac Surgery With Cardiopulmonary Bypass

Background

Acute lung injury (ALI) is a common complication after cardiac surgery with cardiopulmonary bypass (CPB). No precise way, however, is currently available to predict its occurrence. We and others have demonstrated that microparticles (MPs) can induce ALI and were increased in patients with ALI. However, whether MPs can be used to predict ALI after cardiac surgery with CPB remains unknown.

Methods

In this prospective study, 103 patients undergoing cardiac surgery with CPB and 53 healthy subjects were enrolled. MPs were isolated from the plasma before, 12 h after, and 3 d after surgery. The size distributions of MPs were measured by the LitesizerTM 500 Particle Analyzer. The patients were divided into two subgroups (ALI and non-ALI) according to the diagnosis of ALI. Descriptive and correlational analyzes were conducted between the size distribution of MPs and clinical data.

Results

Compared to the non-ALI group, the size at peak and interquartile range (IQR) of MPs in patients with ALI were smaller, but the peak intensity of MPs is higher. Multivariate logistic regression analysis indicated that the size at peak of MPs at postoperative 12 h was an independent risk factor for ALI. The area under the curve (AUC) of peak diameter at postoperative 12 h was 0.803. The best cutoff value of peak diameter to diagnose ALI was 223.05 nm with a sensitivity of 88.0% and a negative predictive value of 94.5%. The AUC of IQR at postoperative 12 h was 0.717. The best cutoff value of IQR to diagnose ALI was 132.65 nm with a sensitivity of 88.0% and a negative predictive value of 92.5%. Combining these two parameters, the sensitivity reached 92% and the negative predictive value was 96%.

Conclusions

Our findings suggested that the size distribution of MPs could be a novel biomarker to predict and exclude ALI after cardiac surgery with CPB.

Improving packed red blood cell storage with a high-viscosity buffered storage solution

BACKGROUND

Massive transfusion with older packed red blood cells is associated with increased morbidity and mortality. As packed red blood cells age, they undergo biochemical and structural changes known as the storage lesion. We developed a novel solution to increase viscosity in stored packed red blood cells. We hypothesized that packed red blood cell storage in this solution would blunt storage lesion formation and mitigate the inflammatory response after resuscitation.

METHODS

Blood was obtained from 8- to 10-week-old C57BL/6 male donor mice or human volunteers and stored as packed red blood cell units for 14 days for mice or 42 days for humans in either standard AS-3 storage solution or EAS-1587, the novel packed red blood cell storage solution. Packed red blood cells were analyzed for microvesicles, cell-free hemoglobin, phosphatidylserine, band-3 protein, glucose utilization, and osmotic fragility. Additional mice underwent hemorrhage and resuscitation with packed red blood cells stored in either AS-3 or EAS-1587. Serum was analyzed for inflammatory markers.

RESULTS

Murine packed red blood cells stored in EAS-1587 demonstrated reductions in microvesicle and cell-free hemoglobin accumulation as well as preserved band-3 expression, increase glucose utilization, reductions in phosphatidylserine expression, and susceptibility to osmotic stress. Serum from mice resuscitated with packed red blood cells stored in EAS-1587 demonstrated reduced proinflammatory cytokines. Human packed red blood cells demonstrated a reduction in microvesicle and cell-free hemoglobin as well as an increase in glucose utilization.

CONCLUSION

Storage of packed red blood cells in a novel storage solution mitigated many aspects of the red blood cell storage lesion as well as the inflammatory response to resuscitation after hemorrhage. This modified storage solution may lead to improvement of packed red blood cell storage and reduce harm after massive transfusion.

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.

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.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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.

Donor-dependent aging of young and old red blood cell subpopulations: Metabolic and functional heterogeneity

BACKGROUND

Characteristics of red blood cells (RBCs) are influenced by donor variability. This study assessed quality and metabolomic variables of RBC subpopulations of varied biologic age in red blood cell concentrates (RCCs) from male and female donors to evaluate their contribution to the storage lesion.

STUDY DESIGN AND METHODS

Red blood cell concentrates from healthy male (n = 6) and female (n = 4) donors were Percoll separated into less dense ("young", Y-RCCs) and dense ("old", O-RCCs) subpopulations, which were assessed weekly for 28 days for changes in hemolysis, mean cell volume (MCV), hemoglobin concentration (MCHC), hemoglobin autofluorescence (HGB), morphology index (MI), oxygen affinity (p50), rigidity, intracellular reactive oxygen species (ROS), calcium ([Ca²⁺ ]), and mass spectrometry-based metabolomics.

RESULTS

Young RCCs having disc-to-discoid morphology showed higher MCV and MI, but lower MCHC, HGB, and rigidity than O-RCCs, having discoid-to-spheroid shape. By Day 14, Y-RCCs retained lower hemolysis and rigidity and higher p50 compared to O-RCCs. Donor sex analyses indicated that females had higher MCV, HGB, ROS, and [Ca²⁺ ] and lower hemolysis than male RBCs, in addition to having a decreased rate of change in hemolysis by Day 28. Metabolic profiling indicated a significant sex-related signature across all groups with increased markers of high membrane lipid remodeling and antioxidant capacity in Y-RCCs, whereas O-RCCs had increased markers of oxidative stress and decreased coping capability.

CONCLUSION

The structural, functional, and metabolic dissimilarities of Y-RCCs and O-RCCs from female and male donors demonstrate RCC heterogeneity, where RBCs from females contribute less to the storage lesion and age slower than males.

Innate coagulability changes with age in stored packed red blood cells

BACKGROUND

Packed red blood cell (pRBC) units administered during resuscitation from hemorrhagic shock are of varied storage ages. We have previously shown that RBC-derived microparticles' impact on thrombogenesis. However, the impact of storage age on pRBC coagulability is unknown. Therefore, we sought to investigate the effect of storage age on innate coagulability and aggregability of stored pRBCs.

METHODS

pRBCs prepared from male C57BL/6J mice were stored in Additive Solution-3 according to our standardized murine blood banking protocols for 14 days. Rotational thromboelastometry (ROTEM) was used to assess the innate coagulation status of fresh and 14-day old pRBCs. Viscoelastic coagulation parameters of clotting time (CT), clot formation time (CFT), alpha angle, and maximum clot firmness (MCF) were analyzed to determine coagulability. Plasma was added to the fresh pRBCs and 15-day old pRBCs to determine if the storage-associated coagulopathy was reversible with plasma. Statistical analyses were conducted with a Student's t-test.

RESULTS

Fifteen-day old pRBCs demonstrated a significant reduction in MCF (10.3 vs. 24.4 mm, P-value <0.001) and alpha angle (6.0 vs. 27.2 degrees, P-value <0.001) as well as significant prolongation of CFT and CT (1126.5 vs. 571.4 s, P-value <0.001) compared to fresh pRBCs. FFP addition to 15-day old and fresh pRBCs, demonstrated a significant reduction in MCF and persistent prolongation of CFT. This suggests that pRBCs lost coagulability as they aged and this deficit was not completely corrected by plasma administration.

CONCLUSIONS

Storage duration may be an important factor in coagulation potential of pRBCs. Transfusion with older pRBCs may contribute to coagulopathy in massively transfused patients.