The red blood cell storage lesion: a method to the madness

Profiles of differential expression of miRNAs in the late stage of red blood cell preservation and their potential roles

OBJECTIVE

To detect the differentially expressed regulatory miRNAs in the late stage of red blood cell (RBC) preservation and predict their roles.

METHODS

Suspended RBCs with different storage periods of 35 day, 42 day, and 50 day were collected for routine blood tests, RNA extraction, and preparation of small RNA sequencing libraries. The constructed libraries were sequenced and the biological functions of differential miRNAs in RBCs in the late storage were analyzed by bioinformatics.

RESULTS

Routine indicators of RBCs in the late stage were not significantly affected by preservation time. The Pearson correlation analysis performing on RBC miRNAs with different storage days revealed that RBC miRNAs changed with the increase of storage days. RBC miRNAs from day 35 (D35), day 42 (D42) and day 50 (D50) showed significant differences (P < 0.05). Compared RBC miRNAs from D42 with these from D35, there were 690 up-regulated miRNAs and 82 down-regulated miRNAs; compared RBC miRNAs from D50 with these from D35, there were 638 up-regulated miRNAs and 123 down-regulated miRNAs; compared RBC miRNAs from D42 with these from D50, there were 271 up-regulated miRNAs and 515 down-regulated miRNAs. GO enrichment analysis of target genes of differential miRNAs were mainly involved in cell metabolism, biosynthesis, protein modification, gene expression and transcriptional regulation of biological processes. KEGG pathway enrichment analysis of miRNA target genes showed that differential miRNA target genes were closely related to pathways in cancer.

CONCLUSION

MiRNAs were differentially expressed in the late stage of RBC preservation, and may be involved in various biological processes, especially cancer.

Leukoreduction of red blood cell units decreases dysregulatory micro RNAs during routine storage: An observational study with In-silico analysis

BACKGROUND

Red Blood cells (RBCs) bring about harmful consequences during storage. MicroRNA (miRNA) dysregulation in stored RBCs could represent potential biomarkers of storage lesions. Although leukoreduction prevents damage to RBCs, it is uncertain whether leukoreduction of RBCs would impact the dysregulation of miRNAs during storage. This study evaluated the potential role of miRNAs for any alteration of leukoreduced (LR) and non-leukoreduced (NLR) RBCs till 21 days of storage.

STUDY DESIGN AND METHODS

In this prospective study, thirty male volunteers' blood was equally divided into leukoreduced RBCs (LR) and NLR RBC (NLR) bags and stored till Day 21 at 4-60c. Selected miRNAs were quantified on Days 0 and 21. Further, bioinformatic tools were used to analyze the selected miRNAs and their predicted target genes (mRNAs) and identify the miRNA-mRNA regulatory relationships.

RESULTS

A significantly higher fold change values of three miRNAs (miR-96-5p, miR-197-3p, miR-769-3p) were observed in NLR RBCs (p < .05). A significantly higher (p < .05) expression levels of miR-150-5p and miR-197-3p were observed in NLR RBCs till 21 days of storage. Further, the correlation with mRNA quantification confirmed the regulatory role of these miRNAs upon functional pathway enrichment analysis.

DISCUSSION

A higher level of dysregulation of miRNAs was observed in NLR RBCs. Validation from In-Silico analysis suggested the regulatory role of miRNAs in cell apoptosis, senescence, and RBC-related signaling pathways. This indicated that stored LR RBCs would likely have better in vivo survival and function following transfusion. However, an in vivo study of miRNA in RBCs is warranted for conclusive evidence.

A deep 96-well plate RBC storage platform for high-throughput screening of novel storage solutions

Background: Red blood cell (RBC) storage solutions, also known as additive solutions (ASs), first developed in the 1970s, enable extended storage of RBCs. Unfortunately, the advancements in this field have been limited, due to labor intensive and time-consuming serial in vitro and in vivo testing, coupled with very high commercialization hurdles. This study examines the utility of deep 96-well plates for preliminary screenings of novel ASs through comparison of RBC storage with the standard PVC bags in terms of hemolysis and ATP levels, under both normoxic (N) and hypoxic/hypocapnic (H) storage conditions. The necessity for the presence of DEHP, normally provided by PVC bags, is also examined. Materials and methods: A pool of 2 ABO compatible RBC units was split between a bag and a plate. Each plate well contained either 1, 2 or 0 PVC strips cut from standard storage bags to supply DEHP. The H bags and plates were processed in an anaerobic glovebox and stored in O2 barrier bags. Hemolysis and ATP were measured bi-weekly using standard methods. Results: Final ATP and hemolysis values for the plate-stored RBCs were comparable to the typical values observed for 6-week storage of leukoreduced AS-3 RBCs in PVC bags under both N and H conditions. Hemolysis was below FDA and EU benchmarks of 1% and 0.8%, respectively, and excluding DEHP from plates during storage, resulted in an inconsequential increase when compared to bag samples. Discussion: In combination with high-throughput metabolomics workflow, this platform provides a highly efficient preliminary screening platform to accelerate the initial testing and consequent development of novel RBC ASs.

Blood Transfusion Reactions-A Comprehensive Review of the Literature including a Swiss Perspective

Blood transfusions have been the cornerstone of life support since the introduction of the ABO classification in the 20th century. The physiologic goal is to restore adequate tissue oxygenation when the demand exceeds the offer. Although it can be a life-saving therapy, blood transfusions can lead to serious adverse effects, and it is essential that physicians remain up to date with the current literature and are aware of the pathophysiology, initial management and risks of each type of transfusion reaction. We aim to provide a structured overview of the pathophysiology, clinical presentation, diagnostic approach and management of acute transfusion reactions based on the literature available in 2022. The numbers of blood transfusions, transfusion reactions and the reporting rate of transfusion reactions differ between countries in Europe. The most frequent transfusion reactions in 2020 were alloimmunizations, febrile non-hemolytic transfusion reactions and allergic transfusion reactions. Transfusion-related acute lung injury, transfusion-associated circulatory overload and septic transfusion reactions were less frequent. Furthermore, the COVID-19 pandemic has challenged the healthcare system with decreasing blood donations and blood supplies, as well as rising concerns within the medical community but also in patients about blood safety and transfusion reactions in COVID-19 patients. The best way to prevent transfusion reactions is to avoid unnecessary blood transfusions and maintain a transfusion-restrictive strategy. Any symptom occurring within 24 h of a blood transfusion should be considered a transfusion reaction and referred to the hemovigilance reporting system. The initial management of blood transfusion reactions requires early identification, immediate interruption of the transfusion, early consultation of the hematologic and ICU departments and fluid resuscitation.

A 3D-printed transfusion platform reveals beneficial effects of normoglycemic erythrocyte storage solutions and a novel rejuvenating solution

A set of 3D-printed analytical devices were developed to investigate erythrocytes (ERYs) processed in conventional and modified storage solutions used in transfusion medicine. During storage, prior to transfusion into a patient recipient, ERYs undergo many chemical and physical changes that are not completely understood. However, these changes are thought to contribute to an increase in post-transfusion complications, and even an increase in mortality rates. Here, a reusable fluidic device (fabricated with additive manufacturing technologies) enabled the evaluation of ERYs prior to, and after, introduction into a stream of flowing fresh ERYs, thus representing components of an in vivo ERY transfusion on an in vitro platform. Specifically, ERYs stored in conventional and glucose-modified solutions were assayed by chemiluminescence for their ability to release flow-induced ATP. The ERY's deformability was also determined throughout the storage duration using a novel membrane transport approach housed in a 3D-printed scaffold. Results show that hyperglycemic conditions permanently alter ERY deformability, which may explain the reduced ATP release, as this phenomenon is related to cell deformability. Importantly, the reduced deformability and ATP release were reversible in an in vitro model of transfusion; specifically, when stored cells were introduced into a flowing stream of healthy cells, the ERY-derived release of ATP and cell deformability both returned to states similar to that of non-stored cells. However, after 1-2 weeks of storage, the deleterious effects of the storage were permanent. These results suggest that currently approved hyperglycemic storage solutions are having adverse effects on stored ERYs used in transfusion medicine and that normoglycemic storage may reduce the storage lesion, especially for cells stored for longer than 14 days.

Neonatal red blood cell transfusion

Transfusions are more common in premature infants with approximately 40% of low birth weight infants and up to 90% of extremely low birth weight infants requiring red blood cell transfusion. Although red blood cell transfusion can be life-saving in these preterm infants, it has been associated with higher rates of complications including necrotizing enterocolitis, bronchopulmonary dysplasia, retinopathy of prematurity and possibly abnormal neurodevelopment. The main objective of this review is to assess current red blood cell transfusion practices in the neonatal intensive care unit, to summarize available neonatal transfusion guidelines published in different countries and to emphasize the wide variation in transfusion thresholds that exists for red blood cell transfusion. This review also addresses certain issues specific to red blood cell processing for the neonatal population including storage time, irradiation, cytomegalovirus (CMV) prevention strategies and patient blood management. Future research avenues are proposed to better define optimal transfusion practice in neonatal intensive care units.

The emerging role of red blood cells in cytokine signalling and modulating immune cells

For many years red blood cells have been described as inert bystanders rather than participants in intercellular signalling, immune function, and inflammatory processes. However, studies are now reporting that red blood cells from healthy individuals regulate immune cell activity and maturation, and red blood cells from disease cohorts are dysfunctional. These cells have now been shown to bind more than 50 cytokines and have been described as a sink for these molecules, and the loss of this activity has been correlated with disease progression. In this review, we summarise what is currently understood about the role of red blood cells in cytokine signalling and in modulating the activity of immune cells. We also discuss the implications of these findings for transfusion medicine and in furthering our understanding of anaemia of chronic inflammation. By bringing these disparate units of work together, we aim to shine a light on an area that requires significantly more investigation.

Review of current transfusion therapy and blood banking practices

Transfusion Medicine is a dynamically evolving field. Recent high-quality research has reshaped the paradigms guiding blood transfusion. As increasing evidence supports the benefit of limiting transfusion, guidelines have been developed and disseminated into clinical practice governing optimal transfusion of red cells, platelets, plasma and cryoprecipitate. Concepts ranging from transfusion thresholds to prophylactic use to maximal storage time are addressed in guidelines. Patient blood management programs have developed to implement principles of patient safety through limiting transfusion in clinical practice. Data from National Hemovigilance Surveys showing dramatic declines in blood utilization over the past decade demonstrate the practical uptake of current principles guiding patient safety. In parallel with decreasing use of traditional blood products, the development of new technologies for blood transfusion such as freeze drying and cold storage has accelerated. Approaches to policy decision making to augment blood safety have also changed. Drivers of these changes include a deeper understanding of emerging threats and adverse events based on hemovigilance, and an increasing healthcare system expectation to align blood safety decision making with approaches used in other healthcare disciplines.

Blood, sweat, and tears: Red Blood Cell-Omics study objectives, design, and recruitment activities

BACKGROUND

The Red Blood Cell (RBC)-Omics study was initiated to build a large data set containing behavioral, genetic, and biochemical characteristics of blood donors with linkage to outcomes of the patients transfused with their donated RBCs.

STUDY DESIGN AND METHODS

The cohort was recruited from four US blood centers. Demographic and donation data were obtained from center records. A questionnaire to assess pica, restless leg syndrome, iron supplementation, hormone use, and menstrual and pregnancy history was completed at enrollment. Blood was obtained for a complete blood count, DNA, and ferritin testing. A leukocyte-reduced RBC sample was transferred to a custom storage bag for hemolysis testing at Storage Days 39 to 42. A subset was recalled to evaluate the kinetics and stability of hemolysis measures.

RESULTS

A total of 13,403 racially/ethnically diverse (12% African American, 12% Asian, 8% Hispanic, 64% white, and 5% multiracial/other) donors of both sexes were enrolled and ranged from 18 to 90 years of age; 15% were high-intensity donors (nine or more donations in the prior 24 mo without low hemoglobin deferral). Data elements are available for 97% to 99% of the cohort.

CONCLUSIONS

The cohort provides demographic, behavioral, biochemical, and genetic data for a broad range of blood donor studies related to iron metabolism, adverse consequences of iron deficiency, and differential hemolysis (including oxidative and osmotic stress perturbations) during RBC storage. Linkage to recipient outcomes may permit analysis of how donor characteristics affect transfusion efficacy. Repository DNA, plasma, and RBC samples should expand the usefulness of the current data set.

Transfusion of red blood cells stored for shorter versus longer duration for all conditions

BACKGROUND

Red blood cell (RBC) transfusion is a common treatment for anaemia in many conditions. The safety and efficacy of transfusing RBC units that have been stored for different durations before a transfusion is a current concern. The duration of storage for a RBC unit can be up to 42 days. If evidence from randomised controlled trials (RCT) were to indicate that clinical outcomes are affected by storage duration, the implications for inventory management and clinical practice would be significant.

OBJECTIVES

To assess the effects of using red blood cells (RBCs) stored for a shorter versus a longer duration, or versus RBCs stored for standard practice duration, in people requiring a RBC transfusion.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, PubMed (for epublications), LILACS, Transfusion Evidence Library, Web of Science CPCI-S and four international clinical trial registries on 20 November 2017.

SELECTION CRITERIA

We included RCTs that compared transfusion of RBCs of shorter versus longer storage duration, or versus standard practice storage duration.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods.

MAIN RESULTS

We included 22 trials (42,835 participants) in this review.The GRADE quality of evidence ranged from very low to moderate for our primary outcome of in-hospital and short-term mortality reported at different time points.Transfusion of RBCs of shorter versus longer storage duration Eleven trials (2249 participants) compared transfusion of RBCs of shorter versus longer storage duration. Two trials enrolled low birth weight neonates, two enrolled children with severe anaemia secondary to malaria or sickle cell disease, and eight enrolled adults across a range of clinical settings (intensive care, cardiac surgery, major elective surgery, hospitalised in-patients, haematology outpatients). We judged only two trials to be at low risk of bias across all domains; most trials had an unclear risk for multiple domains.Transfusion of RBCs of shorter versus longer storage duration probably leads to little or no difference in mortality at seven-day follow-up (risk ratio (RR) 1.42, 95% confidence interval (CI) 0.66 to 3.06; 1 trial, 3098 participants; moderate quality evidence) or 30-day follow-up (RR 0.85, 95%CI 0.50 to 1.45; 2 trials, 1121 participants; moderate quality evidence) in adults undergoing major elective cardiac or non-cardiac surgery.For neonates, no studies reported on the primary outcome of in-hospital or short-term mortality. At 40 weeks gestational age, the effect of RBCs of shorter versus longer storage duration on the risk of death was uncertain, as the quality of evidence is very low (RR 0.90, 95% CI 0.41 to 1.85; 1 trial, 52 participants).The effect of RBCs of shorter versus longer storage duration on the risk of death in children with severe anaemia was also uncertain within 24 hours of transfusion (RR 1.50, 95% CI 0.43 to 5.25; 2 trials, 364 participants; very low quality evidence), or at 30-day follow-up (RR 1.40, 95% CI 0.45 to 4.31; 1 trial, 290 participants; low quality evidence).Only one trial, in children with severe anaemia (290 participants), reported adverse transfusion reactions. Only one child in each arm experienced an adverse reaction within 24 hours of transfusion.Transfusion of RBCs of shorter versus standard practice storage duration Eleven trials (40,588 participants) compared transfusion of RBCs of shorter versus standard practice storage duration. Three trials enrolled critically ill term neonates; two of these enrolled very low birth weight neonates. There were no trials in children. Eight trials enrolled critically ill and non-critically ill adults, with most being hospitalised. We judged four trials to be at low risk of bias across all domains with the others having an unclear risk of bias across multiple domains.Transfusion of RBCs of shorter versus standard practice storage duration probably leads to little or no difference in adult in-hospital mortality (RR 1.05, 95% CI 0.97 to 1.14; 4 trials, 25,704 participants; moderate quality evidence), ICU mortality (RR 1.06, 95% CI 0.98 to 1.15; 3 trials, 13,066 participants; moderate quality evidence), or 30-day mortality (RR 1.04, 95% CI 0.96 to 1.13; 4 trials, 7510 participants;moderate quality evidence).Two of the three trials that enrolled neonates reported that there were no adverse transfusion reactions. One trial reported an isolated case of cytomegalovirus infection in participants assigned to the standard practice storage duration group. Two trials in critically ill adults reported data on transfusion reactions: one observed no difference in acute transfusion reactions between arms (RR 0.67, 95% CI 0.19 to 2.36, 2413 participants), but the other observed more febrile nonhaemolytic reactions in the shorter storage duration arm (RR 1.48, 95% CI 1.13 to 1.95, 4919 participants).Trial sequential analysis showed that we may now have sufficient evidence to reject a 5% relative risk increase or decrease of death within 30 days when transfusing RBCs of shorter versus longer storage duration across all patient groups.

AUTHORS' CONCLUSIONS

The effect of storage duration on clinically important outcomes has now been investigated in large, high quality RCTs, predominantly in adults. There appears to be no evidence of an effect on mortality that is related to length of storage of transfused RBCs. However, the quality of evidence in neonates and children is low. The current practice in blood banks of using the oldest available RBCs can be continued safely. Additional RCTs are not required, but research using alternative study designs, should focus on particular subgroups (e.g. those requiring multiple RBC units) and on factors affecting RBC quality.

MicroRNA Dysregulation Associated with Red Blood Cell Storage

Introduction

Stored red blood cells (RBCs) undergo storage lesions involving morphological, physiological and biochemical changes. MicroRNAs (miRNAs) have important functions in cell apoptosis and life processes. Therefore, the aim of this study was to explore potential roles of miRNAs in the damage of stored RBCs.

Methods

Blood samples were collected from 13 healthy male O-type donors, and leuko-reduced RBCs were divided into fresh RBC group and 20-day storage RBC group.

Results

Eight predicted miRNAs with modified expressions with an intersection ≥ 3 were found dysregulated in the 20-day storage RBC group and involved in apoptosis and senescence signaling pathway: miR-31-5p, miR-196a-5p, miR-203a, miR-654-3p and miR-769-3p were increased, while miR-96-5P, miR-150-5P and miR-197-3p were decreased. Evidence associating miR-31-5p, miR-203a, miR-654 and miR-769 to RBCs or blood in general are not available.

Conclusions

Dysregulated miRNAs might represent potential biomarkers to identify storage lesions, and their detection might help to evaluate the quality of stored RBCs.

In premature infants there is no decrease in 24-hour posttransfusion allogeneic red blood cell recovery after 42 days of storage

BACKGROUND

Critically ill preterm very-low-birthweight (VLBW) neonates (birthweight ≤ 1.5 kg) frequently develop anemia that is treated with red blood cell (RBC) transfusions. Although RBCs transfused to adults demonstrate progressive decreases in posttransfusion 24-hour RBC recovery (PTR₂₄ ) during storage-to a mean of approximately 85% of the Food and Drug Administration-allowed 42-day storage-limited data in infants indicate no decrease in PTR₂₄ with storage.

STUDY DESIGN AND METHODS

We hypothesized that PTR₂₄ of allogeneic RBCs transfused to anemic VLBW newborns: 1) will be greater than PTR₂₄ of autologous RBCs transfused into healthy adults and 2) will not decrease with increasing storage duration. RBCs were stored at 4°C for not more than 42 days in AS-3 or AS-5. PTR₂₄ was determined in 46 VLBW neonates using biotin-labeled RBCs and in 76 healthy adults using ⁵¹ Cr-labeled RBCs. Linear mixed-model analysis was used to estimate slopes and intercepts of PTR₂₄ versus duration of RBC storage.

RESULTS

For VLBW newborns, the estimated slope of PTR₂₄ versus storage did not decrease with the duration of storage (p = 0.18) while for adults it did (p < 0.0001). These estimated slopes differed significantly in adults compared to newborns (p = 0.04). At the allowed 42-day storage limit, projected mean neonatal PTR₂₄ was 95.9%; for adults, it was 83.8% (p = 0.0002).

CONCLUSIONS

These data provide evidence that storage duration of allogeneic RBCs intended for neonates can be increased without affecting PTR₂₄ . This conclusion supports the practice of transfusing RBCs stored up to 42 days for small-volume neonatal transfusions to limit donor exposure.

Short-term effects of stored homologous red blood cell transfusion on cardiorespiratory function and inflammation: an experimental study in a hypovolemia model

The pathophysiological mechanisms associated with the effects of red blood cell (RBC) transfusion on cardiopulmonary function and inflammation are unclear. We developed an experimental model of homologous 14-days stored RBC transfusion in hypovolemic swine to evaluate the short-term effects of transfusion on cardiopulmonary system and inflammation. Sixteen healthy male anesthetized swine (68±3.3 kg) were submitted to controlled hemorrhage (25% of blood volume). Two units of non-filtered RBC from each animal were stored under blood bank conditions for 14 days. After 30 min of hypovolemia, the control group (n=8) received an infusion of lactated Ringer's solution (three times the removed volume). The transfusion group (n=8) received two units of homologous 14-days stored RBC and lactated Ringer's solution in a volume that was three times the difference between blood removed and blood transfusion infused. Both groups were followed up for 6 h after resuscitation with collection of hemodynamic and respiratory data. Cytokines and RNA expression were measured in plasma and lung tissue. Stored RBC transfusion significantly increased mixed oxygen venous saturation and arterial oxygen content. Transfusion was not associated with alterations on pulmonary function. Pulmonary concentrations of cytokines were not different between groups. Gene expression for lung cytokines demonstrated a 2-fold increase in mRNA level for inducible nitric oxide synthase and a 0.5-fold decrease in mRNA content for IL-21 in the transfused group. Thus, stored homologous RBC transfusion in a hypovolemia model improved cardiovascular parameters but did not induce significant effects on microcirculation, pulmonary inflammation and respiratory function up to 6 h after transfusion.

Models for the red blood cell lifespan

The lifespan of red blood cells (RBCs) plays an important role in the study and interpretation of various clinical conditions. Yet, confusion about the meanings of fundamental terms related to cell survival and their quantification still exists in the literature. To address these issues, we started from a compartmental model of RBC populations based on an arbitrary full lifespan distribution, carefully defined the residual lifespan, current age, and excess lifespan of the RBC population, and then derived the distributions of these parameters. For a set of residual survival data from biotin-labeled RBCs, we fit models based on Weibull, gamma, and lognormal distributions, using nonlinear mixed effects modeling and parametric bootstrapping. From the estimated Weibull, gamma, and lognormal parameters we computed the respective population mean full lifespans (95 % confidence interval): 115.60 (109.17-121.66), 116.71 (110.81-122.51), and 116.79 (111.23-122.75) days together with the standard deviations of the full lifespans: 24.77 (20.82-28.81), 24.30 (20.53-28.33), and 24.19 (20.43-27.73). We then estimated the 95th percentiles of the lifespan distributions (a surrogate for the maximum lifespan): 153.95 (150.02-158.36), 159.51 (155.09-164.00), and 160.40 (156.00-165.58) days, the mean current ages (or the mean residual lifespans): 60.45 (58.18-62.85), 60.82 (58.77-63.33), and 57.26 (54.33-60.61) days, and the residual half-lives: 57.97 (54.96-60.90), 58.36 (55.45-61.26), and 58.40 (55.62-61.37) days, for the Weibull, gamma, and lognormal models respectively. Corresponding estimates were obtained for the individual subjects. The three models provide equally excellent goodness-of-fit, reliable estimation, and physiologically plausible values of the directly interpretable RBC survival parameters.

Predicting storage-dependent damage to red blood cells using nitrite oxidation kinetics, peroxiredoxin-2 oxidation, and hemoglobin and free heme measurements

BACKGROUND

Storage-dependent damage to red blood cells (RBCs) varies significantly. Identifying RBC units that will undergo higher levels of hemolysis during storage may allow for more efficient inventory management decision-making. Oxidative-stress mediates storage-dependent damage to RBCs and will depend on the oxidant:antioxidant balance. We reasoned that this balance or redox tone will serve as a determinant of how a given RBC unit stores and that its assessment in "young" RBCs will predict storage-dependent hemolysis.

STUDY DESIGN AND METHODS

RBCs were sampled from bags and segments stored for 7 to 42 days. Redox tone was assessed by nitrite oxidation kinetics and peroxiredoxin-2 (Prx-2) oxidation. In parallel, hemolysis was assessed by measuring cell-free hemoglobin (Hb) and free heme (hemin). Correlation analyses were performed to determine if Day 7 measurements predicted either the level of hemolysis at Day 35 or the increase in hemolysis during storage.

RESULTS

Higher Day 7 Prx-2 oxidation was associated with higher Day 35 Prx-2 oxidation, suggesting that early assessment of this variable may identify RBCs that will incur the most oxidative damage during storage. RBCs that oxidized nitrite faster on Day 7 were associated with the greatest levels of storage-dependent hemolysis and increases in Prx-2 oxidation. An inverse relationship between storage-dependent changes in oxyhemoglobin and free heme was observed underscoring an unappreciated reciprocity between these molecular species. Moreover, free heme was higher in the bag compared to paired segments, with opposite trends observed for free Hb.

CONCLUSION

Measurement of Prx-2 oxidation and nitrite oxidation kinetics early during RBC storage may predict storage-dependent damage to RBC including hemolysis-dependent formation of free Hb and heme.

Prolonged storage of packed red blood cells for blood transfusion

BACKGROUND

A blood transfusion is an acute intervention, used to address life- and health-threatening conditions on a short-term basis. Packed red blood cells are most often used for blood transfusion. Sometimes blood is transfused after prolonged storage but there is continuing debate as to whether transfusion of 'older' blood is as beneficial as transfusion of 'fresher' blood.

OBJECTIVES

To assess the clinical benefits and harms of prolonged storage of packed red blood cells, in comparison with fresh, on recipients of blood transfusion.

SEARCH METHODS

We ran the search on 1st May 2014. We searched the Cochrane Injuries Group Specialized Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase (OvidSP), CINAHL (EBSCO Host) and two other databases. We also searched clinical trials registers and screened reference lists of the retrieved publications and reviews. We updated this search in June 2015 but these results have not yet been incorporated.

SELECTION CRITERIA

Randomised clinical trials including participants assessed as requiring red blood cell transfusion were eligible for inclusion. Prolonged storage was defined as red blood cells stored for ≥ 21 days in a blood bank. We did not apply limits regarding the duration of follow-up, or country where the study took place. We excluded trials where patients received a combination of short- and long-stored blood products, and also trials without a clear definition of prolonged storage.

DATA COLLECTION AND ANALYSIS

We independently performed study selection, risk of bias assessment and data extraction by at least two review authors. The major outcomes were death from any cause, transfusion-related acute lung injury, and adverse events. We estimated relative risk for dichotomous outcomes. We measured statistical heterogeneity using I(2). We used a random-effects model to synthesise the findings.

MAIN RESULTS

We identified three randomised clinical trials, involving a total of 120 participants, comparing packed red blood cells with ≥ 21 days storage ('prolonged' or 'older') versus packed red blood cells with < 21 days storage ('fresh'). We pooled data to assess the effect of prolonged storage on death from any cause. The confidence in the results from these trials was very low, due to the bias in their design and their limited sample sizes.The estimated effect of packed red blood cells with ≥ 21 days storage versus packed red blood cells with < 21 days storage for the outcome death from any cause was imprecise (5/45 [11.11%] versus 2/46 [4.34%]; RR 2.36; 95% CI 0.65 to 8.52; I(2): 0%, P = 0.26, very low quality of evidence). Trial sequential analysis, with only two trials, shows that we do not yet have convincing evidence that older packed red blood cells induce a 20% relative risk reduction of death from any cause compared with fresher packed red blood cells. No trial included other outcomes of interest specified in this review, namely transfusion-related acute lung injury, postoperative infections, and adverse events. The safety profile is unknown.

AUTHORS' CONCLUSIONS

Recognising the limitations of the review, relating to the size and nature of the included trials, this Cochrane Review provides no evidence to support or reject the use of packed red blood cells for blood transfusion which have been stored for ≥ 21 days ('prolonged' or 'older') compared with those stored for < 21 days ('fresh'). These results are based on three small single centre trials with high risks of bias. There is insufficient evidence to determine the effects of fresh or older packed red blood cells for blood transfusion. Therefore, we urge readers to interpret the trial results with caution. The results from four large ongoing trials will help to inform future updates of this review.

Transfusion of fresher versus older red blood cells for all conditions

BACKGROUND

Red blood cell transfusion is a common treatment for anaemia in many clinical conditions. One current concern is uncertainty as to the clinical consequences (notably efficacy and safety) of transfusing red blood cell units that have been stored for different durations of time before a transfusion. If evidence from randomised controlled trials were to indicate that clinical outcomes are affected by storage age, the implications for inventory management and clinical practice would be significant.

OBJECTIVES

To assess the effects of using fresher versus older red blood cells in people requiring a red blood cell transfusion.

SEARCH METHODS

We ran the search on 29th September 2014. We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (OvidSP), Embase (OvidSP), CINAHL (EBSCO), PubMed (for e-publications), three other databases and trial registers.

SELECTION CRITERIA

We included randomised controlled trials comparing fresher red blood cell transfusion versus active transfusion of older red blood cells, and comparing fresher red blood cell transfusion versus current standard practice. All definitions of 'fresher' and 'older'/'standard practice' red blood cells were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted from the trial report data on adverse red blood cell transfusion reactions, when reported.

MAIN RESULTS

We included 16 trials (1864 participants) in the review. Eight trials (279 participants) compared transfusion of fresher red blood cells versus transfusion of older stored red blood cells ('fresher' vs 'older'). Eight trials (1585 participants) compared the transfusion of fresher red blood cells versus current standard practice ('fresher' vs 'standard practice'). Five trials enrolled neonates, one trial enrolled children and 12 trials enrolled adults. Overall sample sizes were small: only two trials randomly assigned more than 100 participants.We performed no meta-analyses for a variety of reasons: no uniform definition of 'fresher' or 'older' red blood cell storage; overlap in the distribution of the age of red blood cells; and heterogeneity in measurements and reporting of outcomes of interest to this review. We tabulated and reported results by individual trial. Overall risk of bias was low or unclear, with four incidences of high risk of bias: in allocation concealment (three trials) and in incomplete outcome data (one trial).No trial measured all of the outcomes of interest in this review. Four trials comparing 'fresher' with 'older' red blood cells reported the primary outcome: mortality within seven days (one study; 74 participants) and at 30 days (three trials; 62 participants). Six trials comparing 'fresher' with 'standard practice' red blood cells reported the primary outcome: mortality within seven days (three studies; 159 participants) and at 30 days (three trials; 1018 participants). All 10 trials reported no clear differences in mortality at either time point between intervention arms.Three trials comparing 'fresher' with 'standard practice' red blood cells reported red blood cell transfusion-associated adverse events. No adverse reactions were reported in two trials, and one incidence of cytomegalovirus (CMV) infection was described in the 'standard practice' arm in one trial.Overall the trials reported no clear difference between either of the intervention comparisons in long-term mortality (three trials; 478 participants); clinically accepted measures of multiple organ dysfunction (two trials: 399 participants); incidence of in-hospital infection (two trials; 429 participants); duration of mechanical ventilation (three trials: 95 participants); and number of participants requiring respiratory organ support (five trials; 528 participants) or renal support (one trial; 57 participants). The outcome 'physiological markers of oxygen consumption or alterations in microcirculation' was reported by 11 studies, but the measures used were highly varied, and no formal statistical analysis was undertaken.

AUTHORS' CONCLUSIONS

Several factors precluded firm conclusions about the clinical outcomes of transfusing red blood cell units that have been stored for different periods of time before transfusion, including differences in clinical population and setting, diversity in the interventions used, methodological limitations and differences in how outcomes were measured and reported.No clear differences in the primary outcome - death - were noted between 'fresher' and 'older' or 'standard practice' red blood cells in trials that reported this outcome. Findings of a large number of ongoing trials will be incorporated into this review when they are published.Updates of this review will explore the degree of overlap in trials between 'fresher', 'older' and 'standard practice' storage ages of red blood cells and will consider whether the size of any observed effects is dependent on recipient factors such as clinical background, patient age or clinical presentation.

Established and theoretical factors to consider in assessing the red cell storage lesion

The collection and storage of red blood cells (RBCs) is a logistical necessity to provide sufficient blood products. However, RBC storage is an unnatural state, resulting in complicated biological changes, referred to collectively as the "storage lesion." Specifics of the storage lesion have been studied for decades, including alterations to cellular properties, morphology, molecular biology of carbohydrates, proteins and lipids, and basic metabolism. Recently, mass spectrometry-based "omics" technology has been applied to the RBC storage lesion, resulting in many new observations, the initial effects of which are more information than understanding. Meanwhile, clinical research on RBC transfusion is considering both the efficacy and also the potential untoward effects of transfusing stored RBCs of different ages and storage conditions. The myriad biological changes that have now been observed during the storage lesion have been extensively reviewed elsewhere. This article focuses rather on an analysis of our current understanding of the biological effects of different elements of the storage lesion, in the context of evolving new clinical understanding. A synopsis is presented of both established and theoretical considerations of the RBC storage lesion and ongoing efforts to create a safer and more efficacious product.

The heritability of hemolysis in stored human red blood cells

BACKGROUND

The transfusion of red blood cells (RBCs) with maximum therapeutic efficacy is a major goal in transfusion medicine. One of the criteria used in determining stored RBC quality is end-of-storage hemolysis. Between donors, a wide range of hemolysis is observed under identical storage conditions. Here, a potential mechanism for this wide range is investigated. We hypothesize that the magnitude of hemolysis is a heritable trait. Also, we investigated correlations between hemolysis and RBC metabolites; this will establish pathways influencing hemolysis as future targets for genetic analysis.

STUDY DESIGN AND METHODS

Units of RBCs from identical and nonidentical twins were collected and stored under standard conditions for 56 days. Hemolysis, adenosine triphosphate (ATP), and total glutathione (tGSH) were measured throughout storage. Nontargeted metabolic analyses were performed on RBCs that had been stored for 28 days. Heritability was determined by comparing values between identical and nonidentical twins.

RESULTS

Hemolysis was found to be heritable (mean > 45%) throughout the storage period. Potential correlations were observed between hemolysis and metabolites from the purine metabolism, lysolipid, and glycolysis pathways. These also exhibited heritability (>20%). No correlation was found with ATP or tGSH.

CONCLUSION

The susceptibility of RBCs to lysis during storage is partly determined by inheritance. We have also uncovered several pathways that are candidate targets for future genomewide association studies. These findings will aid in the design of better storage solutions and the development of donor screening tools that minimize hemolysis during storage.

Peroxiredoxin-2 recycling is inhibited during erythrocyte storage

AIMS

Transfusion with stored red blood cells (RBCs) is associated with increased morbidity and mortality. Peroxiredoxin-2 (Prx-2) is a primary RBC antioxidant that limits hydrogen peroxide (H2O2)-mediated toxicity. Whether Prx-2 activity is altered during RBC storage is not known.

RESULTS

Basal and H2O2-induced Prx-2 activity was measured in RBCs (stored for 7-35 days). Basal Prx-2 thiol oxidation increased with RBC age, whereas H2O2-dependent formation of dimeric Prx-2 was similar. However, reduction of Prx-2 dimers to monomers became progressively slower with RBC storage, which was associated with increased H2O2-induced hemolysis. Surprisingly, no change in the NADPH-dependent thioredoxin (Trx)/Trx-reductase system, which recycles dimeric Prx-2, was observed in stored RBCs. Using mouse RBCs expressing human wild type (β93Cys) or hemoglobin (Hb) in which the conserved β93Cys residue is replaced by Ala (β93Ala), a role for this thiol in modulating Prx-2 reduction was demonstrated. Specifically, Prx-2 recycling was blunted in β93Ala RBC, which was reversed by carbon monoxide-treatment, suggesting that heme autoxidation-derived H2O2 maintains Prx-2 in the oxidized form in these cells. Moreover, assessment of the oxidative state of the β93Cys in RBCs during storage showed that while it remained reduced on intraerythrocytic Hb in stored RBC, it was oxidized to dehydroalanine on hemolyzed or extracellular Hb.

INNOVATION

A novel mechanism for regulated Prx-2 activity in RBC via the β93Cys residue is suggested.

CONCLUSION

These data highlight the potential for slower Prx-2 recycling and β93Cys oxidation in modulating storage-dependent damage of RBCs and in mediating post-transfusion toxicity.

Red blood cell storage duration and trauma

Numerous retrospective clinical studies suggest that transfusion of longer stored red blood cells (RBCs) is associated with an independent risk of poorer outcomes for certain groups of patients, including trauma, intensive care, and cardiac surgery patients. Large multicenter randomized controlled trials are currently underway to address the concern about RBC storage duration. However, none of these randomized controlled trials focus specifically on trauma patients with hemorrhage. Major trauma, particularly due to road accidents, is the leading cause of critical injury in the younger-than-40-year-old age group. Severe bleeding associated with major trauma induces hemodynamic dysregulation that increases the risk of hypoxia, coagulopathy, and potentially multiorgan failure, which can be fatal. In major trauma, a multitude of stress-associated changes occur to the patient's RBCs, including morphological changes that increase cell rigidity and thereby alter blood flow hemodynamics, particularly in the microvascular vessels, and reduce RBC survival. Initial inflammatory responses induce deleterious cellular interactions, including endothelial activation, RBC adhesion, and erythrophagocytosis that are quickly followed by profound immunosuppressive responses. Stored RBCs exhibit similar biophysical characteristics to those of trauma-stressed RBCs. Whether transfusion of RBCs that exhibit storage lesion changes exacerbates the hemodynamic perturbations already active in the trauma patient is not known. This article reviews findings from several recent nonrandomized studies examining RBC storage duration and clinical outcomes in trauma patients. The rationale for further research on RBC storage duration in the trauma setting is provided.

Heritability of glutathione and related metabolites in stored red blood cells

Red blood cells (RBCs) collected for transfusion deteriorate during storage. This deterioration is termed the "RBC storage lesion." There is increasing concern over the safety, therapeutic efficacy, and toxicity of transfusing longer-stored units of blood. The severity of the RBC storage lesion is dependent on storage time and varies markedly between individuals. Oxidative damage is considered a significant factor in the development of the RBC storage lesion. In this study, the variability during storage and heritability of antioxidants and metabolites central to RBC integrity and function were investigated. In a classic twin study, we determined the heritability of glutathione (GSH), glutathione disulfide (GSSG), the status of the GSSG,2H(+)/2GSH couple (Ehc), and total glutathione (tGSH) in donated RBCs over 56 days of storage. Intracellular GSH and GSSG concentrations both decrease during storage (median net loss of 0.52 ± 0.63 mM (median ± SD) and 0.032 ± 0.107 mM, respectively, over 42 days). Taking into account the decline in pH, Ehc became more positive (oxidized) during storage (median net increase of 35 ± 16 mV). In our study population heritability estimates for GSH, GSSG, tGSH, and Ehc measured over 56 days of storage are 79, 60, 67, and, 75%, respectively. We conclude that susceptibility of stored RBCs to oxidative injury due to variations in the GSH redox buffer is highly variable among individual donors and strongly heritable. Identifying the genes that regulate the storage-related changes in this redox buffer could lead to the development of new methods to minimize the RBC storage lesion.

How cell number and cellular properties of blood-banked red blood cells of different cell ages decline during storage

AIMS

Numerous studies have suggested that transfusion of red blood cells (RBCs) stored over a long period of time may induce harmful effects due to storage-induced lesions. However, the underlying mechanisms responsible for this damage have not been identified. Furthermore, it is unclear why and how up to 30% of long-stored RBCs disappear from the circulation within 24 hours after transfusion. The aim of this study was to determine how the cell number of RBCs of different ages changes during storage and how these cells undergo cumulative structural and functional changes with storage time.

METHODS AND RESULTS

We used Percoll centrifugation to fractionate the RBCs in blood bank stored RBC units into different aged sub-populations and then measured the number of intact cells in each sub-population as well the cells' biomechanical and biochemical parameters as functions of the storage period. We found that the RBC units stored for ≤ 14 days could be separated into four fractions: the top or young cell fraction, two middle fractions, and the lower or old fraction. However, after 14 days of storage, the cell number and cellular properties declined rapidly whereby the units stored for 21 days only exhibited the three lower fractions and not the young fraction. The cell number within a unit stored for 21 days decreased by 23% compared to a fresh unit and the cells that were lost had hemolyzed into harmful membrane fragments, microparticles, and free hemoglobin. All remaining cells exhibited cellular properties similar to those of senescent cells.

CONCLUSION

In RBC units stored for greater than 14 days, there were fewer intact cells with no healthy cells present, as well as harmful membrane fragments, microparticles, and free hemoglobin. Therefore, transfusion of these stored units would not likely help patients and may induce a series of clinical problems.

In vitro combinations of red blood cell, plasma and platelet components evaluated by thromboelastography

BACKGROUND

Thromboelastography is increasingly used to evaluate coagulation in massively bleeding patients. The aim of this study was to investigate how different combinations of blood components affect in vitro whole blood clotting measured by thromboelastography.

MATERIALS AND METHODS

Packed red blood cells, plasma and platelets from fresh and old blood components were mixed in vitro, in proportions of 4:4:1, 5:5:2, 8:4:1 and 2:1:0, and analysed with thromboelastography. For the ratio 4:4:1 the experiment was done at both 37 °C and 32 °C.

RESULTS

Thromboelastography curves were within normal reference values for the blood component proportions of 4:4:1 and 5:5:2. For 8:4:1, the angle and maximal amplitude were reduced below normal values, indicating low levels of fibrinogen and/or platelets. For the 2:1:0 proportion, all parameters were affected resulting in severely impaired in vitro clot formation. The reaction-time, reflecting the coagulation factor-dependent, initial clot formation, was slightly increased at a low temperature. Prolonged storage of the components did not affect the curve.

DISCUSSION

With the introduction of guidelines on the management of massive bleeding it is important to have tools for the assessment of the new protocols. In vitro evaluation of mixtures of packed red blood cells, plasma and platelets by thromboelastography may be relevant in the prediction of in vivo clot formation and haemostasis.

The heritability of metabolite concentrations in stored human red blood cells

BACKGROUND

The degeneration of red blood cells (RBCs) during storage is a major issue in transfusion medicine. Family studies in the 1960s established the heritability of the RBC storage lesion based on poststorage adenosine triphosphate (ATP) concentrations. However, this critical discovery has not been further explored. In a classic twin study we confirmed the heritability of poststorage ATP concentrations and established the heritability of many other RBC metabolites.

STUDY DESIGN AND METHODS

ATP concentrations and metabolomic profiles were analyzed in RBC samples from 18 twin pairs. On samples stored for 28 days, the heritability of poststorage ATP concentrations were 64 and 53% in CP2D- and AS-3-stored RBCs, respectively.

RESULTS

Metabolomic analyses identified 87 metabolites with an estimated heritability of 20% or greater. Thirty-six metabolites were significantly correlated with ATP concentrations (p ≤ 0.05) and 16 correlated with borderline significance (0.05 ≤ p ≤ 0.10). Of the 52 metabolites that correlated significantly with ATP, 24 demonstrated 20% or more heritability. Pathways represented by heritable metabolites included glycolysis, membrane remodeling, redox homeostasis, and synthetic and degradation pathways.

CONCLUSION

We conclude that many RBC metabolite concentrations are genetically influenced during storage. Future studies of key metabolic pathways and genetic modifiers of RBC storage could lead to major advances in RBC storage and transfusion therapy.

Impact of the age of transfused red blood cells in the trauma population: a feasibility study

Following injury, transfusion of red blood cells (RBCs) of increased storage duration has been associated with an increased morbidity and mortality. Prospective trials focusing on the impact of the storage age of RBCs in severely bleeding trauma patients have failed to accrue patients. This has been attributed to an inability to maintain a large inventory of fresh RBCs, and the difficulties in obtaining consent in severely bleeding trauma patients. To address these issues, we performed a prospective, observational pilot study to evaluate the feasibility of conducting a trial focusing on RBC age in patients following injury.

METHODS

Patients with bleeding due to trauma were transfused RBCs ≤10 day old if they were ABO blood Type O (Group O) or were transfused the oldest RBCs in inventory if they were Type A, B or AB (Group A/B/AB). Clinicians were unaware of the specific age of the RBCs.

RESULTS

63 patients were analyzed (Group O, n=19; Group A/B/AB, n=44). Half of all patients had severe injuries ISS (median 22). The median admission base deficit was -5 mEq/L, and median total 24h use of RBC and FFP was 1.2 L. The age of RBCs transfused to Group O was significantly lower than for Group A/B/AB [median (IQR) A/B/AB=18.4 (11.4-25.4) days, and Group O=6 (4.2-7.8) days; p<0.001].

CONCLUSIONS

It appears feasible to conduct a RBC age trial in trauma patients using ABO blood type to construct comparative groups. Adequate RBC age separation between cohorts and reduced RBC age in the "young" group of patients who received units ≤10 days old was achieved.

Measures of stored red blood cell quality

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

The National Heart, Lung, and Blood Institute Recipient Epidemiology and Donor Evaluation Study (REDS-III): a research program striving to improve blood donor and transfusion recipient outcomes

BACKGROUND

The Recipient Epidemiology and Donor Evaluation Study-III (REDS-III) is a 7-year multicenter transfusion safety research initiative launched in 2011 by the National Heart, Lung, and Blood Institute.

STUDY DESIGN AND METHODS

The domestic component involves four blood centers, 12 hospitals, a data coordinating center, and a central laboratory. The international component consists of distinct programs in Brazil, China, and South Africa, which involve US and in-country investigators.

RESULTS

REDS-III is using two major methods to address key research priorities in blood banking and transfusion medicine. First, there will be numerous analyses of large "core" databases; the international programs have each constructed a donor and donation database while the domestic program has established a detailed research database that links data from blood donors and their donations, the components made from these donations, and data extracts from the electronic medical records of the recipients of these components. Second, there are more than 25 focused research protocols involving transfusion recipients, blood donors, or both that either are in progress or are scheduled to begin within the next 3 years. Areas of study include transfusion epidemiology and blood utilization, transfusion outcomes, noninfectious transfusion risks, human immunodeficiency virus-related safety issues (particularly in the international programs), emerging infectious agents, blood component quality, donor health and safety, and other donor issues.

CONCLUSIONS

It is intended that REDS-III serve as an impetus for more widespread recipient and linked donor-recipient research in the United States as well as to help assure a safe and available blood supply in the United States and in international locations.

S-nitrosylation therapy to improve oxygen delivery of banked blood

From the perspectives of disease transmission and sterility maintenance, the world's blood supplies are generally safe. However, in multiple clinical settings, red blood cell (RBC) transfusions are associated with adverse cardiovascular events and multiorgan injury. Because ∼85 million units of blood are administered worldwide each year, transfusion-related morbidity and mortality is a major public health concern. Blood undergoes multiple biochemical changes during storage, but the relevance of these changes to unfavorable outcomes is unclear. Banked blood shows reduced levels of S-nitrosohemoglobin (SNO-Hb), which in turn impairs the ability of stored RBCs to effect hypoxic vasodilation. We therefore reasoned that transfusion of SNO-Hb-deficient blood may exacerbate, rather than correct, impairments in tissue oxygenation, and that restoration of SNO-Hb levels would improve transfusion efficacy. Notably in mice, administration of banked RBCs decreased skeletal muscle pO2, but infusion of renitrosylated cells maintained tissue oxygenation. In rats, hemorrhage-induced reductions in muscle pO2 were corrected by SNO-Hb-repleted RBCs, but not by control, stored RBCs. In anemic awake sheep, stored renitrosylated, but not control RBCs, produced sustained improvements in O2 delivery; in anesthetized sheep, decrements in hemodynamic status, renal blood flow, and kidney function incurred following transfusion of banked blood were also prevented by renitrosylation. Collectively, our findings lend support to the idea that transfusions may be causally linked to ischemic events and suggest a simple approach to prevention (i.e., SNO-Hb repletion). If these data are replicated in clinical trials, renitrosylation therapy could have significant therapeutic impact on the care of millions of patients.

Neutrophils release extracellular DNA traps during storage of red blood cell units

BACKGROUND

Blood transfusion is associated with an increased risk of organ damage, infection, and alloimmunity. Neutrophil extracellular traps (NETs) are extracellular chromatin fibers decorated with neutrophil granular proteins that have been linked to cytotoxicity, thrombosis, and autoimmunity. We questioned whether neutrophils in blood products release NETs during storage and thus could contribute to adverse reactions from blood transfusions.

STUDY DESIGN AND METHODS

We analyzed supernatants and blood smears of human red blood cell (RBC) units that either were or were not leukoreduced before storage for markers of NETs.

RESULTS

We identified extracellular DNA, which was associated with histones and myeloperoxidase, a marker of neutrophil granules, in supernatants and blood smears of nonleukoreduced RBC units. These markers of NETs were absent in leukoreduced RBC units. Importantly, NETs passed through blood transfusion filters and could therefore potentially be infused into patients.

CONCLUSIONS

Our studies indicate that NETs are liberated during storage of nonleukoreduced RBC units. Future studies should address whether NETs in RBC units could potentially contribute to transfusion-associated complications.

Red blood cells stored for increasing periods produce progressive impairments in nitric oxide-mediated vasodilation

BACKGROUND

Clinical outcomes in transfused patients may be affected by the duration of blood storage, possibly due to red blood cell (RBC)-mediated disruption of nitric oxide (NO) signaling, a key regulator of vascular tone and blood flow.

STUDY DESIGN AND METHODS

AS-1 RBC units stored up to 42 days were sampled at selected storage times. Samples were added to aortic rings ex vivo, a system where NO-mediated vasodilation could be experimentally controlled.

RESULTS

RBC units showed storage-dependent changes in plasma hemoglobin (Hb), RBC 2,3-diphosphoglycerate acid, and RBC adenosine triphosphate conforming to expected profiles. When freshly collected (Day 0) blood was added to rat aortic rings, methacholine (MCh) stimulated substantial NO-mediated vasodilation. In contrast, MCh produced no vasodilation in the presence of blood stored for 42 days. Surprisingly, the vasoinhibitory effects of stored RBCs were almost totally mediated by RBCs themselves: removal of the supernatant did not attenuate the inhibitory effects, while addition of supernatant alone to the aortic rings only minimally inhibited MCh-stimulated relaxation. Stored RBCs did not inhibit vasodilation by a direct NO donor, demonstrating that the RBC-mediated vasoinhibitory mechanism did not work by NO scavenging.

CONCLUSIONS

These studies have revealed a previously unrecognized vasoinhibitory activity of stored RBCs, which is more potent than the described effects of free Hb and works through a different mechanism that does not involve NO scavenging but may function by reducing endothelial NO production. Through this novel mechanism, transfusion of small volumes of stored blood may be able to disrupt physiologic vasodilatory responses and thereby possibly cause adverse clinical outcomes.

Red blood cells stored for increasing periods produce progressive impairments in nitric oxide-mediated vasodilation

BACKGROUND

Clinical outcomes in transfused patients may be affected by the duration of blood storage, possibly due to red blood cell (RBC)-mediated disruption of nitric oxide (NO) signaling, a key regulator of vascular tone and blood flow.

STUDY DESIGN AND METHODS

AS-1 RBC units stored up to 42 days were sampled at selected storage times. Samples were added to aortic rings ex vivo, a system where NO-mediated vasodilation could be experimentally controlled.

RESULTS

RBC units showed storage-dependent changes in plasma hemoglobin (Hb), RBC 2,3-diphosphoglycerate acid, and RBC adenosine triphosphate conforming to expected profiles. When freshly collected (Day 0) blood was added to rat aortic rings, methacholine (MCh) stimulated substantial NO-mediated vasodilation. In contrast, MCh produced no vasodilation in the presence of blood stored for 42 days. Surprisingly, the vasoinhibitory effects of stored RBCs were almost totally mediated by RBCs themselves: removal of the supernatant did not attenuate the inhibitory effects, while addition of supernatant alone to the aortic rings only minimally inhibited MCh-stimulated relaxation. Stored RBCs did not inhibit vasodilation by a direct NO donor, demonstrating that the RBC-mediated vasoinhibitory mechanism did not work by NO scavenging.

CONCLUSIONS

These studies have revealed a previously unrecognized vasoinhibitory activity of stored RBCs, which is more potent than the described effects of free Hb and works through a different mechanism that does not involve NO scavenging but may function by reducing endothelial NO production. Through this novel mechanism, transfusion of small volumes of stored blood may be able to disrupt physiologic vasodilatory responses and thereby possibly cause adverse clinical outcomes.

The effects of red blood cell preparation method on in vitro markers of red blood cell aging and inflammatory response

BACKGROUND

Studies are currently under way examining whether the age of stored red blood cells (RBCs) affects clinical outcome in transfusion recipients. The effects of storage duration on the RBC storage lesion are well documented, while fewer studies are available regarding the effect of RBC production method. In this study, we compared in vitro RBC quality variables and markers of inflammatory response in apheresis and whole blood (WB)-derived RBCs, specifically those prepared after an overnight room temperature hold (RTH) of WB.

STUDY DESIGN AND METHODS

SAGM RBCs, prepared from WB after overnight RTH (n = 10), were compared to SAGM RBCs prepared using an apheresis device (Alyx, n = 10). As a control, SAGM RBCs were also prepared within 2 hours of WB collection (2-hr WB, n = 10). All RBCs were stored at 4°C for 42 days with weekly assay of in vitro variables, cytokines and/or chemokines, and neutrophil activation after incubation with RBC supernatant.

RESULTS

RTH WB RBCs exhibited decreased levels of 2,3-diphosphoglycerate acid (2.3 μmol/g hemoglobin [Hb] ± 2.1 vs. 13.7 ± 1.3 μmol/g Hb) and morphology (160 ± 10 vs. 192 ± 5) on Day 1 and increased hemolysis (0.45 ± 0.21% vs. 0.31 ± 0.09%) and microparticles (6.1 ± 2.8/10(3) RBCs vs. 3.9 ± 1.1/10(3) RBCs) on Day 42 compared to apheresis RBCs. Gro-α and ENA-78 cytokine levels were significantly higher in RTH WB than Alyx RBCs during storage. CD11b expression was highest in neutrophils exposed to supernatant from RTH WB RBCs (p < 0.05).

CONCLUSION

RBC preparation method has a meaningful effect on the RBC storage lesion, which should be taken into account in addition to length of storage.

Blood transfusions with high levels of contaminating soluble HLA-I correlate with levels of soluble CD8 in recipients' plasma; a new control factor in soluble HLA-I-mediated transfusion-modulated immunomodulation?

BACKGROUND

The cause of transfusion-related immunomodulation (TRIM) has proved tantalisingly elusive. An ever-growing body of evidence indicates that the infusion of large amounts of soluble and cell-associated antigens into a recipient can somehow induce TRIM. One soluble molecule that has been implicated in TRIM is soluble human leucocyte antigen I (sHLA-I). However, patients infused with large amounts of sHLA-I do not always and unambiguously experience TRIM. As soluble CD8 (sCD8) molecules have been shown to capable of binding membrane and soluble HLA-I molecules, we focused on sCD8 as a possible modulator of sHLA-I-mediated TRIM.

MATERIAL AND METHODS

To this aim we compared the up-regulation of circulating sCD8 in plasma from patients suffering from the same pathology, but chronically transfused with two different blood derivatives: pre- and post-storage leucodepleted red blood cells which contain low and high levels of contaminating sHLA-I, respectively.

RESULTS

Significantly larger amounts of sCD8 circulating molecules were detectable in the plasma of patients transfused with post-storage leucodepleted red blood cells whose supernatants contained significantly larger amounts of sHLA-I contaminating molecules.

CONCLUSION

With the limitation of indirect evidence, this report introduces a new facet of the bioactivity of sCD8 as a possible modulator of sHLA-I-mediated TRIM.

Will clinical studies elucidate the connection between the length of storage of transfused red blood cells and clinical outcomes? An analysis based on the simulation of randomized controlled trials

BACKGROUND

The temporal pattern of the biologic mechanism linking red blood cell (RBC) storage duration with clinical outcomes is yet unknown. This study investigates how such a temporal pattern can affect the power of randomized controlled trials (RCT) to detect a relevant clinical outcome mediated by the transfusion of stored RBCs.

STUDY DESIGN AND METHODS

This study was a computer simulation of four RCTs, each using a specific categorization of the RBC storage time. The trial's endpoint was evaluated assuming five hypothetical temporal patterns for the biologic mechanism linking RBC storage duration with clinical outcomes.

RESULTS

Power of RCTs to unveil a significant association between RBC storage duration and clinical outcomes was critically dependent on a complex interaction among three factors: 1) the way the RBC storage time is categorized in the trial design, 2) the temporal pattern assumed for the RBC storage lesion, and 3) the age distribution of RBCs in the inventory from which they are picked up for transfusion. For most combinations of these factors, the power of RCTs to detect a significant treatment effect was below 80%. All the four simulated RCTs had a very low power to disclose a harmful clinical effect confined to last week of the maximum 42-day shelf life of stored RBCs.

CONCLUSIONS

Ongoing RCTs may lack enough power to settle the issue of whether or not the transfusion of stored blood has a negative clinical impact. A precautionary reduction of the maximum storage time to 35 days is advisable.

Alternative blood products and clinical needs in transfusion medicine

The primary focus of national blood programs is the provision of a safe and adequate blood supply. This goal is dependent on regular voluntary donations and a regulatory infrastructure that establishes and enforces standards for blood safety. Progress in ex vivo expansion of blood cells from cell sources including peripheral blood, cord blood, induced pluripotent stem cells, and human embryonic stem cell lines will likely make alternative transfusion products available for clinical use in the near future. Initially, alloimmunized patients and individuals with rare blood types are most likely to benefit from alternative products. However, in developed nations voluntary blood donations are projected to be inadequate in the future as blood usage by individuals 60 years and older increases. In developing nations economic and political challenges may impede progress in attaining self-sufficiency. Under these circumstances, ex vivo generated red cells may be needed to supplement the general blood supply.

The effects of long-term storage of human red blood cells on the glutathione synthesis rate and steady-state concentration

BACKGROUND

Banked red blood cells (RBCs) undergo changes that reduce their viability after transfusion. Dysfunction of the glutathione (GSH) antioxidant system may be implicated. We measured the rate of GSH synthesis in stored RBCs and applied a model of GSH metabolism to identify storage-dependent changes that may affect GSH production.

STUDY DESIGN AND METHODS

RBC units (n = 6) in saline-adenine-glucose-mannitol (SAGM) solution were each divided into four transfusion bags and separate treatments were applied: 1) SAGM (control), 2) GSH precursor amino acids, 3) aminoguanidine, and 4) glyoxal. RBCs were sampled during 6 weeks of storage. Rejuvenated RBCs were also analyzed.

RESULTS

After 6 weeks, the ATP concentration declined to 50 ± 5.5% (p < 0.05) of that in the fresh RBCs. For control RBCs, the GSH concentration decreased by 27 ± 6.5% (p < 0.05) and the rate of GSH synthesis by 45 ± 8% (p < 0.05). The rate of GSH synthesis in rejuvenated and amino acid-treated RBCs was unchanged after 6 weeks. Modeling identified that the decline in GSH synthesis was due to decreased intracellular substrate concentrations and reduced amino acid transport, secondary to decreased ATP concentration.

CONCLUSION

This study has uniquely shown that the glutathione synthesis rate decreased significantly after 6 weeks in stored RBCs. Our results have identified potential opportunities for improvement of banked blood storage.