Attenuation of Red Blood Cell Storage Lesions with Vitamin C

Intraoperative cell salvage reduces postoperative allogeneic blood transfusion and shortens off-bed time in simultaneous bilateral total hip arthroplasty: a single-center retrospective study

BACKGROUND

Simultaneous bilateral total hip arthroplasty (SI-THA) results in more blood loss and a greater need for postoperative allogeneic blood transfusion (ABT). Previous studies have reported that multimodal patient blood management (PBM) strategies were associated with a smaller effect of intraoperative cell salvage (ICS) in unilateral total hip arthroplasty. However, there are few studies on the role of ICS in SI-THA. This study aims to explore the effect of ICS with multimodal PBM strategies on SI-THA and to identify risk factors associated with ABT.

METHODS

This retrospective matched cohort study included 72 patients in the ICS group and 72 patients in the control group who were matched according to age, sex, and year of hospitalization. Demographic data, hematological indicators, blood loss, and ABT were compared between the two groups. Logistic regression analysis was performed to identify independent risk factors for postoperative ABT. Postoperative outcomes were also recorded.

RESULTS

In the cohort of 144 patients, 27 patients (37.5%) in the ICS group while 45 patients (62.5%) in the control group received postoperative ABT after SI-THA. Compared with the control group, the ICS group showed significant differences in terms of blood loss, postoperative hemoglobin and hematocrit. The transfused volume of allogeneic red blood cells per ABT patient was also lower in the ICS group. Multivariate logistic regression analysis indicated that sex, the utilization of ICS, and preoperative hematocrit level were identified as independent factors associated with postoperative ABT. The utilization of ICS significantly shortened off-bed time and length of hospital stay, but had no effect on early pain and functional outcomes.

CONCLUSION

The utilization of ICS can significantly affect postoperative ABT in SI-THA patients with multimodal PBM strategies. Sex, the utilization of ICS and preoperative hematocrit level were identified as independent factors associated with postoperative ABT. The utilization of ICS promoted weight-bearing functional exercises, but had no effect on early outcomes.

Extracellular vesicles: effectors of transfusion-related acute lung injury

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

Synergistic activity of vitamin-C and vitamin-E to ameliorate the efficacy of stored erythrocytes

OBJECTIVES

Erythrocytes are exposed to oxidative stress during storage and can be stored for up to 42 days (in AS-7) under blood bank conditions for transfusion. Vitamin-C and Vitamin-E have proved beneficial in diminishing oxidative stress. Therefore, this study aims to investigate the combined effects of Vitamin-C and Vitamin-E on erythrocytes during storage.

MATERIALS AND METHODS

Blood was collected from male Wistar rats and erythrocytes were isolated and stored in AS-7 (Additive Solution) at 4 °C for 35 days. Erythrocytes were grouped into i) Controls and ii) Experimentals [Vitamin-C (10 mM) and Vitamin-E (2 mM)]. Antioxidant and oxidative stress markers were assessed at weekly intervals. Statistical analyses were performed by using GraphPad Prism software.

RESULTS

Hemoglobin increased on days 7 and 14 in the Experimentals. Superoxide dismutase activity elevated on days 7 & 14 in Controls and on day 7 in Experimentals. Catalase activity increased on day 21 in both groups. Protein carbonyls decreased on days 21 and 28 in Experimentals. Thiobarbituric acid reactive substances decreased from day 14 in both groups. Conjugate dienes decreased on days 21 & 35 in the Experimentals. Glutathione increased from day 14 in both groups. Superoxides decreased on days 14, 28 & 35 in Controls and from day 14 in Experimentals.

CONCLUSION

Vitamin-C and Vitamin-E have been beneficial in terms of hemoglobin, antioxidants, protein & lipid oxidations and superoxides in stored erythrocytes. Therefore, this study provides new avenues for the development of effective storage solutions which will have a clinical impact in erythrocyte transfusions.

Oxidants and Antioxidants in the Redox Biochemistry of Human Red Blood Cells

Red blood cells (RBCs) are exposed to both external and internal sources of oxidants that challenge their integrity and compromise their physiological function and supply of oxygen to tissues. Autoxidation of oxyhemoglobin is the main source of endogenous RBC oxidant production, yielding superoxide radical and then hydrogen peroxide. In addition, potent oxidants from other blood cells and the surrounding endothelium can reach the RBCs. Abundant and efficient enzymatic systems and low molecular weight antioxidants prevent most of the damage to the RBCs and also position the RBCs as a sink of vascular oxidants that allow the body to maintain a healthy circulatory system. Among the antioxidant enzymes, the thiol-dependent peroxidase peroxiredoxin 2, highly abundant in RBCs, is essential to keep the redox balance. A great part of the RBC antioxidant activity is supported by an active glucose metabolism that provides reducing power in the form of NADPH via the pentose phosphate pathway. There are several RBC defects and situations that generate oxidative stress conditions where the defense mechanisms are overwhelmed, and these include glucose-6-phosphate dehydrogenase deficiencies (favism), hemoglobinopathies like sickle cell disease and thalassemia, as well as packed RBCs for transfusion that suffer from storage lesions. These oxidative stress-associated pathologies of the RBCs underline the relevance of redox balance in these anucleated cells that lack a mechanism of DNA-inducible antioxidant response and rely on a complex and robust network of antioxidant systems.

The time-course linkage between hemolysis, redox, and metabolic parameters during red blood cell storage with or without uric acid and ascorbic acid supplementation

Oxidative phenomena are considered to lie at the root of the accelerated senescence observed in red blood cells (RBCs) stored under standard blood bank conditions. It was recently shown that the addition of uric (UA) and/or ascorbic acid (AA) to the preservative medium beneficially impacts the storability features of RBCs related to the handling of pro-oxidant triggers. This study constitutes the next step, aiming to examine the links between hemolysis, redox, and metabolic parameters in control and supplemented RBC units of different storage times. For this purpose, a paired correlation analysis of physiological and metabolism parameters was performed between early, middle, and late storage in each subgroup. Strong and repeated correlations were observed throughout storage in most hemolysis parameters, as well as in reactive oxygen species (ROS) and lipid peroxidation, suggesting that these features constitute donor-signatures, unaffected by the diverse storage solutions. Moreover, during storage, a general "dialogue" was observed between parameters of the same category (e.g., cell fragilities and hemolysis or lipid peroxidation and ROS), highlighting their interdependence. In all groups, extracellular antioxidant capacity, proteasomal activity, and glutathione precursors of preceding time points anticorrelated with oxidative stress lesions of upcoming ones. In the case of supplemented units, factors responsible for glutathione synthesis varied proportionally to the levels of glutathione itself. The current findings support that UA and AA addition reroutes the metabolism to induce glutathione production, and additionally provide mechanistic insight and footing to examine novel storage optimization strategies.

Supplementation with uric and ascorbic acid protects stored red blood cells through enhancement of non-enzymatic antioxidant activity and metabolic rewiring

Redox imbalance and oxidative stress have emerged as generative causes of the structural and functional degradation of red blood cells (RBC) that happens during their hypothermic storage at blood banks. The aim of the present study was to examine whether the antioxidant enhancement of stored RBC units following uric (UA) and/or ascorbic acid (AA) supplementation can improve their storability as well as post-transfusion phenotypes and recovery by using in vitro and animal models, respectively. For this purpose, 34 leukoreduced CPD/SAGM RBC units were aseptically split in 4 satellite units each. UA, AA or their mixture were added in the three of them, while the fourth was used as control. Hemolysis as well as redox and metabolic parameters were studied in RBC units throughout storage. The addition of antioxidants maintained the quality parameters of stored RBCs, (e.g., hemolysis, calcium homeostasis) and furthermore, shielded them against oxidative defects by boosting extracellular and intracellular (e.g., reduced glutathione; GSH) antioxidant powers. Higher levels of GSH seemed to be obtained through distinct metabolic rewiring in the modified units: methionine-cysteine metabolism in UA samples and glutamine production in the other two groups. Oxidatively-induced hemolysis, reactive oxygen species accumulation and membrane lipid peroxidation were lower in all modifications compared to controls. Moreover, denatured/oxidized Hb binding to the membrane was minor, especially in the AA and mix treatments during middle storage. The treated RBC were able to cope against pro-oxidant triggers when found in a recipient mimicking environment in vitro, and retain control levels of 24h recovery in mice circulation. The currently presented study provides (a) a detailed picture of the effect of UA/AA administration upon stored RBCs and (b) insight into the differential metabolic rewiring when distinct antioxidant "enhancers" are used.

Erythrocyte osmotic fragility is not linked to vitamin C nutriture in adults with well-controlled type 2 diabetes

Erythrocyte fragility is amplified by oxidative stress and linked to diabetes-specific microvascular disease. Vitamin C supplementation improves glycemic indices in adults with type 2 diabetes (T2D) by improving antioxidant status. This cross-sectional study examined the relationships between vitamin C status and erythrocyte osmotic fragility in adults with or without T2D. Participants provided a fasting blood sample for erythrocyte osmotic fragility testing as a function of hypotonic NaCl concentrations. Additionally, plasma was stabilized with metaphosphoric acid prior to vitamin C analysis using isocratic reverse-phase UV-HPLC separation. Participants were grouped as diagnosed T2D (n = 14; 36% female; 55.5 ± 8.2 y; 31.5 ± 9.0 kg/m²; HbA1c: 7.4 ± 1.9%; plasma vitamin C: 36.0 ± 12.2 μM) or no diabetes (n = 16; 69% female; 38.7 ± 13.5 y; 26.8 ± 6.6 kg/m²; HbA1c: 5.4 ± 0.3%; plasma vitamin C: 34.8 ± 10.9 μM). Participant characteristics differed between groups only for age and hemoglobin A1c (HbA1c; p < 0.05). All hemolysis parameters were in normal ranges for the participants with T2D, and no significant differences in hemolysis parameters were noted between those with or without T2D. However, among participants with T2D, the NaCl concentration eliciting 50% hemolysis was higher for those with low (<7%) vs. high (>7%) HbA1c values (p = 0.037) indicating a slightly higher erythrocyte fragility in the former group. Vitamin C status did not impact any of the hemolysis parameters in adults with or without T2D. Thus, erythrocyte fragility was not elevated in T2D, and vitamin C nutriture was not related to erythrocyte fragility in adults with well-controlled T2D.

Erythrocyte degradation, metabolism, secretion, and communication with immune cells in the blood during sepsis: A review

Sepsis is a health issue that affects millions of people worldwide. It was assumed that erythrocytes were affected by sepsis. However, in recent years, a number of studies have shown that erythrocytes affect sepsis as well. When a pathogen invades the human body, it infects the blood and organs, causing infection and sepsis-related symptoms. Pathogens change the internal environment, increasing the levels of reactive oxygen species, influencing erythrocyte morphology, and causing erythrocyte death, i.e., eryptosis. Characteristics of eryptosis include cell shrinkage, membrane blebbing, and surface exposure of phosphatidylserine (PS). Eryptotic erythrocytes increase immune cell proliferation, and through PS, attract macrophages that remove the infected erythrocytes. Erythrocyte-degraded hemoglobin derivatives and heme deteriorate infection; however, they could also be metabolized to a series of derivatives. The result that erythrocytes play an anti-infection role during sepsis provides new perspectives for treatment. This review focuses on erythrocytes during pathogenic infection and sepsis.

ZOOMICS: Comparative Metabolomics of Red Blood Cells From Guinea Pigs, Humans, and Non-human Primates During Refrigerated Storage for Up to 42 Days

Unlike other rodents, guinea pigs (Cavia porcellus) have evolutionarily lost their capacity to synthesize vitamin C (ascorbate) de novo and, like several non-human primates and humans, rely on dietary intake and glutathione-dependent recycling to cope with oxidant stress. This is particularly relevant in red blood cell physiology, and especially when modeling blood storage, which exacerbates erythrocyte oxidant stress. Herein we provide a comprehensive metabolomics analysis of fresh and stored guinea pig red blood cell concentrates (n = 20), with weekly sampling from storage day 0 through 42. Results were compared to previously published ZOOMICS studies on red blood cells from three additional species with genetic loss of L-gulonolactone oxidase function, including humans (n = 21), olive baboons (n = 20), and rhesus macaques (n = 20). While metabolic trends were comparable across all species, guinea pig red blood cells demonstrated accelerated alterations of the metabolic markers of the storage lesion that are consistent with oxidative stress. Compared to the other species, guinea pig red blood cells showed aberrant glycolysis, pentose phosphate pathway end product metabolites, purine breakdown products, methylation, glutaminolysis, and markers of membrane lipid remodeling. Consistently, guinea pig red blood cells demonstrated higher end storage hemolysis, and scanning electron microscopy confirmed a higher degree of morphological alterations of their red blood cells, as compared to the other species. Despite a genetic inability to produce ascorbate that is common to the species evaluated, guinea pig red blood cells demonstrate accelerated oxidant stress under standard storage conditions. These data may offer relevant insights into the basal and cold storage metabolism of red blood cells from species that cannot synthesize endogenous ascorbate.

Restoration of Physiological Levels of Uric Acid and Ascorbic Acid Reroutes the Metabolism of Stored Red Blood Cells

After blood donation, the red blood cells (RBCs) for transfusion are generally isolated by centrifugation and then filtrated and supplemented with additive solution. The consecutive changes of the extracellular environment participate to the occurrence of storage lesions. In this study, the hypothesis is that restoring physiological levels of uric and ascorbic acids (major plasmatic antioxidants) might correct metabolism defects and protect RBCs from the very beginning of the storage period, to maintain their quality. Leukoreduced CPD-SAGM RBC concentrates were supplemented with 416 µM uric acid and 114 µM ascorbic acid and stored during six weeks at 4 °C. Different markers, i.e., haematological parameters, metabolism, sensitivity to oxidative stress, morphology and haemolysis were analyzed. Quantitative metabolomic analysis of targeted intracellular metabolites demonstrated a direct modification of several metabolite levels following antioxidant supplementation. No significant differences were observed for the other markers. In conclusion, the results obtained show that uric and ascorbic acids supplementation partially prevented the metabolic shift triggered by plasma depletion that occurs during the RBC concentrate preparation. The treatment directly and indirectly sustains the antioxidant protective system of the stored RBCs.

Temporal sequence of the human RBCs' vesiculation observed in nano-scale with application of AFM and complementary techniques

Based on the multimodal characterization of human red blood cells (RBCs), the link between the storage-related sequence of the nanoscale changes in RBC membranes in the relation to their biochemical profile as well as mechanical and functional properties was presented. On the background of the accumulation of RBCs waste products, programmed cell death and impaired rheological properties, progressive alterations in the RBC membranes including changes in their height and diameter as well as the in situ characterization of RBC-derived microparticles (RMPs) on the RBCs surface were presented. The advantage of atomic force microscopy (AFM) in RMPs visualization, even at the very early stage of vesiculation, was shown based on the results revealed by other reference techniques. The nanoscale characterization of RMPs was correlated with a decrease in cholesterol and triglycerides levels in the RBC membranes, proving the link between the lipids leakage from RBCs and the process of vesiculation.

High-Dose Intravenous Ascorbic Acid: Ready for Prime Time in Traumatic Brain Injury?

Traumatic brain injury (TBI) is one of the leading public health problems in the USA and worldwide. It is the number one cause of death and disability in children and adults between ages 1-44. Despite efforts to prevent TBIs, the incidence continues to rise. Secondary brain injury occurs in the first hours and days after the initial impact and is the most effective target for intervention. Inflammatory processes and oxidative stress play an important role in the pathomechanism of TBI and are exacerbated by impaired endogenous defense mechanisms, including depletion of antioxidants. As a reducing agent, free radical scavenger, and co-factor in numerous biosynthetic reactions, ascorbic acid (AA, vitamin C) is an essential nutrient that rapidly becomes depleted in states of critical illness. The administration of high-dose intravenous (IV) AA has demonstrated benefits in numerous preclinical models in the areas of trauma, critical care, wound healing, and hematology. A safe and inexpensive treatment, high-dose IV AA administration gained recent attention in studies demonstrating an associated mortality reduction in septic shock patients. High-quality data on the effects of high-dose IV AA on TBI are lacking. Historic data in a small number of patients demonstrate acute and profound AA deficiency in patients with central nervous system pathology, particularly TBI, and a strong correlation between low AA concentrations and poor outcomes. While replenishing deficient AA stores in TBI patients should improve the brain's ability to tolerate oxidative stress, high-dose IV AA may prove an effective strategy to prevent or mitigate secondary brain injury due to its ability to impede lipid peroxidation, scavenge reactive oxygen species, suppress inflammatory mediators, stabilize the endothelium, and reduce brain edema. The existing preclinical data and limited clinical data suggest that high-dose IV AA may be effective in lowering oxidative stress and decreasing cerebral edema. Whether this translates into improved clinical outcomes will depend on identifying the ideal target patient population and possible treatment combinations, factors that need to be evaluated in future clinical studies. With its excellent safety profile and low cost, high-dose IV AA is ready to be evaluated in the early treatment of TBI patients to mitigate secondary brain injury and improve outcomes.

Glut-1 explains the evolutionary advantage of the loss of endogenous vitamin C-synthesis: The electron transfer hypothesis

Introduction

During evolution, some species including humans, monkeys and fruit bats lost the ability for ascorbic acid (AA) biosynthesis due to inactivation of the enzyme l-gulono-lactone oxidase (GLO) and subsequently became dependent on dietary vitamin C. There are four current hypotheses in relation to the benefit of vitamin C dependence in the context of adaptation and reproduction. Here we advance and test a new ‘electron transfer hypothesis’, which focusses on the role of the expression of glucose transporter 1 (Glut-1) in red blood cells (RBCs) in recycling vitamin C, thereby increasing the efficiency of micronutrient uptake.

Methods

To evaluate the benefit of Glut-1 expression, we determined vitamin C uptake into RBCs and potential release from two different species, humans with l-Gulono-lactone-oxidase (GLO-loss) and pigs with functional GLO.

Results

The oxidized form of vitamin C (dehydroascorbate, DHA) was transported into human RBCs via Glut-1. There was no transport of either the reduced (AA) or the oxidized vitamin in pig erythrocytes.

Conclusion

We propose that the transport of vitamin C increases an intracellular electron pool, which transfers electrons from intracellular ascorbate to extracellular substances like ascorbyl free radical or DHA, resulting in 100-fold smaller daily requirement of this essential redox sensitive micronutrient. This would be an advantage during seasonal changes of the availability from food and may be the key for the survival of individuals without vitamin C biosynthesis.

Lay Summary

40 million years ago some individuals lost the ability to synthesize vitamin C. Why did they survive such as humans until now? Individuals with a specific glucose transporter Glut-1 on their erythrocytes which transports vitamin C need less and are protected from scarcity due to seasons and food competitors.

Cigarette smoking and antioxidant defences in packed red blood cells prior to storage

BACKGROUND

Red blood cells from smoking donors can have more lesions from oxidative stress, decreasing the benefits of blood transfusion. We aimed to explore the effect of cigarette smoking on the oxidative status of packed red blood cells (PRBCs) prior to storage.

MATERIALS AND METHODS

We compared serum vitamin C, plasmatic malondialdehyde (MDA), and non-protein thiol groups (GSH) levels in PRBCs, as well glutathione peroxidase (GPx) and glutathione s-transferase (GST) activity in PRBCs from smoking (n=36) and non-smoking (n=36) donors. We also correlated urinary cotinine levels with these parameters.

RESULTS

Cigarette smoking was associated with decreased serum levels of vitamin C and GPx, and increased GST activity in PRBCs. We found negative correlations between cotinine, GPx activity and vitamin C levels, and a positive correlation between cotinine and GST activity.

DISCUSSION

Cigarette smoking changed antioxidant defences of PRBCs prior to storage and these parameters are correlated with cotinine levels. Increased RBC antioxidants such as GST may reflect an exposure to oxidants during erythropoiesis. Because of the inability of mature RBCs to resynthesise antioxidants, PRBCs from smokers may have higher risk of storage lesions than those from non-smoker donors.

Red blood cell storage lesion: causes and potential clinical consequences

Red blood cells (RBCs) are a specialised organ that enabled the evolution of multicellular organisms by supplying a sufficient quantity of oxygen to cells that cannot obtain oxygen directly from ambient air via diffusion, thereby fueling oxidative phosphorylation for highly efficient energy production. RBCs have evolved to optimally serve this purpose by packing high concentrations of haemoglobin in their cytosol and shedding nuclei and other organelles. During their circulatory lifetimes in humans of approximately 120 days, RBCs are poised to transport oxygen by metabolic/redox enzymes until they accumulate damage and are promptly removed by the reticuloendothelial system. These elaborate evolutionary adaptions, however, are no longer effective when RBCs are removed from the circulation and stored hypothermically in blood banks, where they develop storage-induced damages ("storage lesions") that accumulate over the shelf life of stored RBCs. This review attempts to provide a comprehensive view of the literature on the subject of RBC storage lesions and their purported clinical consequences by incorporating the recent exponential growth in available data obtained from "omics" technologies in addition to that published in more traditional literature. To summarise this vast amount of information, the subject is organised in figures with four panels: i) root causes; ii) RBC storage lesions; iii) physiological effects; and iv) reported outcomes. The driving forces for the development of the storage lesions can be roughly classified into two root causes: i) metabolite accumulation/depletion, the target of various interventions (additive solutions) developed since the inception of blood banking; and ii) oxidative damages, which have been reported for decades but not addressed systemically until recently. Downstream physiological consequences of these storage lesions, derived mainly by in vitro studies, are described, and further potential links to clinical consequences are discussed. Interventions to postpone the onset and mitigate the extent of the storage lesion development are briefly reviewed. In addition, we briefly discuss the results from recent randomised controlled trials on the age of stored blood and clinical outcomes of transfusion.

Redox Potential Measurements in Red Blood Cell Packets Using Nanoporous Gold Electrodes

The redox potential of packed red blood cells (RBCs) was measured over a 56-day storage period using a newly developed potentiometric methodology consisting of a nanoporous gold electrode and a silver chloride coated silver reference electrode. Both milliliter- and microliter-sized volumes were separately evaluated. The addition of Vitamin C (VitC) in differing doses to the packed RBCs was also assessed as a means to improve redox stability and prolong storage duration. For RBCs containing only saline, the open-circuit potential (OCP) was ∼ -80 mV vs Ag/AgCl and drifted slightly with time; greater differences were also noted between different electrodes. The addition of exogenous VitC to the RBC shifts the OCP to more negative values, stabilizes the redox potential, and improves reproducibly between different electrodes due to the poising of blood. Over the 56-day storage period, the redox potential of the RBCs increased slightly, which can be attributed to change in pH and/or increasing oxidative stress during storage. Cyclic voltammograms acquired after open-circuit potential measurements showed a characteristic peak attributed to the oxidation of VitC. This peak decreased during storage with a time constant of 20.8 days. Likewise, the intercellular concentration of VitC increased with a time constant of 20.2 days as measured using a fluorescence assay. Collectively, these results demonstrate the usefulness of electrochemical measurements in the study of stored blood products.

Metabolic effect of alkaline additives and guanosine/gluconate in storage solutions for red blood cells

BACKGROUND

Over a century of advancements in the field of additive solutions for red blood cell (RBC) storage has made transfusion therapy a safe and effective practice for millions of recipients worldwide. Still, storage in the blood bank results in the progressive accumulation of metabolic alterations, a phenomenon that is mitigated by storage in novel storage additives, such as alkaline additive solutions. While novel alkaline additive formulations have been proposed, no metabolomics characterization has been performed to date.

STUDY DESIGN AND METHODS

We performed UHPLC-MS metabolomics analyses of red blood cells stored in SAGM (standard additive in Europe), (PAGGSM), or alkaline additives SOLX, E-SOL 5 and PAG3M for either 1, 21, 35 (end of shelf-life in the Netherlands), or 56 days.

RESULTS

Alkaline additives (especially PAG3M) better preserved 2,3-diphosphoglycerate and adenosine triphosphate (ATP). Deaminated purines such as hypoxanthine were predictive of hemolysis and morphological alterations. Guanosine supplementation in PAGGSM and PAG3M fueled ATP generation by feeding into the nonoxidative pentose phosphate pathway via phosphoribolysis. Decreased urate to hypoxanthine ratios were observed in alkaline additives, suggestive of decreased generation of urate and hydrogen peroxide. Despite the many benefits observed in purine and redox metabolism, alkaline additives did not prevent accumulation of free fatty acids and oxidized byproducts, opening a window for future alkaline formulations including (lipophilic) antioxidants.

CONCLUSION

Alkalinization via different strategies (replacement of chloride anions with either high bicarbonate, high citrate/phosphate, or membrane impermeant gluconate) results in different metabolic outcomes, which are superior to current canonical additives in all cases.