Biochemical assessment of red blood cells during storage by (1)H nuclear magnetic resonance spectroscopy. Identification of a biomarker of their level of protection against oxidative stress

Effects of Different Ratios of Carbohydrate-Fat in Enteral Nutrition on Metabolic Pattern and Organ Damage in Burned Rats

(1) Background: Nutritional support is one of the most important cornerstones in the management of patients with severe burns, but the carbohydrate-to-fat ratios in burn nutrition therapy remain highly controversial. In this study, we aimed to discuss the effects of different ratios of carbohydrate–fat through enteral nutrition on the metabolic changes and organ damage in burned rats. (2) Methods: Twenty-four burned rats were randomly divided into 5%, 10%, 20% and 30% fat nutritional groups. REE and body weight were measured individually for each rat daily. Then, 75% of REE was given in the first week after burns, and the full dose was given in the second week. Glucose tolerance of the rats was measured on days 1, 3, 7, 10 and 14. Blood biochemistry analysis and organ damage analysis were performed after 7 and 14 days of nutritional therapy, and nuclear magnetic resonance (NMR) and insulin content analysis were performed after 14 days. (3) Results: NMR spectra showed significant differences of glucose, lipid and amino acid metabolic pathways. The energy expenditure increased, and body weight decreased significantly after burn injury, with larger change in the 20%, 5% and 30% fat groups, and minimal change in the 10% fat group. The obvious changes in the level of plasma protein, glucose, lipids and insulin, as well as the organ damage, were in the 30%, 20% and 5% fat groups. In relative terms, the 10% fat group showed the least variation and was closest to normal group. (4) Conclusion: Lower fat intake is beneficial to maintaining metabolic stability and lessening organ damage after burns, but percentage of fat supply should not be less than 10% in burned rats.

Comparison of Two Alternative Procedures to Obtain Packed Red Blood Cells for β-Thalassemia Major Transfusion Therapy

β-thalassemia major (βTM) patients require frequent blood transfusions, with consequences that span from allogenic reactions to iron overload. To minimize these effects, βTM patients periodically receive leucodepleted packed red blood cells (P-RBCs) stored for maximum 14 days. The aim of this study was to compare two alternative routine procedures to prepare the optimal P-RBCs product, in order to identify differences in their content that may somehow affect patients’ health and quality of life (QoL). In method 1, blood was leucodepleted and then separated to obtain P-RBCs, while in method 2 blood was separated and leucodepleted after removal of plasma and buffycoat. Forty blood donors were enrolled in two independent centers; couples of phenotypically matched whole blood units were pooled, divided in two identical bags and processed in parallel following the two methods. Biochemical properties, electrolytes and metabolic composition were tested after 2, 7 and 14 days of storage. Units prepared with both methods were confirmed to have all the requirements necessary for βTM transfusion therapy. Nevertheless, RBCs count and Hb content were found to be higher in method-1, while P-RBCs obtained with method 2 contained less K⁺, iron and storage lesions markers. Based on these results, both methods should be tested in a clinical perspective study to determine a possible reduction of transfusion-related complications, improving the QoL of βTM patients, which often need transfusions for the entire lifespan.

Majid R, Ibraheem ZO, Mediani A, Ismail IS, Unyah NZ, Alhassan Abdullahi S, Nordin N, Nasiru Wana M, Basir R. Investigation of Andrographolide Effect on Non-Infected Red Blood Cells Using the 1H-NMR-Based Metabolomics Approach

Andrographolide (AG) has been shown to have several medicinal and pharmaceutical effects, such as antimicrobial, anti-inflammatory, antioxidant, anti-diabetic, and anti-malarial activities. Moreover, studies to assess the pharmacological effect of AG on the metabolic changes of uninfected red blood cells (uRBCs) have not yet been investigated. This study aims to evaluate the pharmacological effects of AG compared to chloroquine (CQ) on the metabolic variations of uRBCs in vitro using a proton nuclear magnetic resonance (¹H-NMR)-based metabolomics approach coupled with multivariate data analysis (MVDA). Forty-one metabolites were successfully identified by ¹H-NMR. The results of the unsupervised data analysis principal component analysis (PCA) showed ideal differentiation between AG and CQ. PC1 and PC2 accounted for 71.4% and 17.7% of the explained variation, respectively, with a total variance of 89.10%. Based on S-plot and VIP values, a total of 28 and 32 metabolites were identified as biomarkers in uRBCs-AG and uRBCs-CQ, respectively. In uRBCs treated with AG, ten metabolic pathways were determined to be disturbed, including riboflavin metabolism, d-glutamate and d-glutamine metabolism, phenylalanine metabolism, glutathione metabolism, proline and arginine metabolism, arginine biosynthesis, citrate cycle, glycolysis/gluconeogenesis, and pyruvate metabolism as well as alanine, aspartate, and glutamate metabolism. In contrast, in CQ-treated uRBCs, nine affected metabolic pathways were determined, which involved the same metabolic pathways for uRBCs-AG, except for glutathione metabolism. These findings suggest an evident relationship between AG and CQ associated with metabolic changes in intact RBCs after being exposed to the treatment. The metabolomics results could allow useful comprehensive insights into the underlying mechanism of the action of AG and CQ on red blood cells. Consequently, the ¹H-NMR-based metabolomics approach was successfully utilized to identify the pharmacological effects of AG and CQ on the metabolic variations of uRBCs.

Metabolic Profiles of Whole, Parotid and Submandibular/Sublingual Saliva

The detection of salivary molecules associated with pathological and physiological alterations has encouraged the search of novel and non-invasive diagnostic biomarkers for oral health evaluation. While genomic, transcriptomic, and proteomic profiles of human saliva have been reported, its metabolic composition is a topic of research: metabolites in submandibular/sublingual saliva have never been analyzed systematically. In this study, samples of whole, parotid, and submandibular/sublingual saliva from 20 healthy donors, without dental or periodontal diseases, were examined by nuclear magnetic resonance. We identified metabolites which are differently distributed within the three saliva subtypes (54 in whole, 49 in parotid, and 36 in submandibular/sublingual saliva). Principal component analysis revealed a distinct cluster for whole saliva and a partial overlap for parotid and submandibular/sublingual metabolites. We found exclusive metabolites for each subtype: 2-hydroxy-3-methylvalerate, 3-methyl-glutarate, 3-phenylpropionate, 4-hydroxyphenylacetate, 4-hydroxyphenyllactate, galactose, and isocaproate in whole saliva; caprylate and glycolate in submandibular/sublingual saliva; arginine in parotid saliva. Salivary metabolites were classified into standard and non-proteinogenic amino acids and amines; simple carbohydrates; organic acids; bacterial-derived metabolites. The identification of a salivary gland-specific metabolic composition in healthy people provides the basis to invigorate the search for salivary biomarkers associated with oral and systemic diseases.

Nicotine exposure increases markers of oxidant stress in stored red blood cells from healthy donor volunteers

BACKGROUND

Cigarette smoking is a frequent habit across blood donors (approx. 13% of the donor population), that could compound biologic factors and exacerbate oxidant stress to stored red blood cells (RBCs).

STUDY DESIGN AND METHODS

As part of the REDS-III RBC-Omics (Recipient Epidemiology Donor Evaluation Study III Red Blood Cell-Omics) study, a total of 599 samples were sterilely drawn from RBC units stored under blood bank conditions at Storage Days 10, 23, and 42 days, before testing for hemolysis parameters and metabolomics. Quantitative measurements of nicotine and its metabolites cotinine and cotinine oxide were performed against deuterium-labeled internal standards.

RESULTS

Donors whose blood cotinine levels exceeded 10 ng/mL (14% of the tested donors) were characterized by higher levels of early glycolytic intermediates, pentose phosphate pathway metabolites, and pyruvate-to-lactate ratios, all markers of increased basal oxidant stress. Consistently, increased glutathionylation of oxidized triose sugars and lipid aldehydes was observed in RBCs donated by nicotine-exposed donors, which were also characterized by increased fatty acid desaturation, purine salvage, and methionine oxidation and consumption via pathways involved in oxidative stress-triggered protein damage-repair mechanisms.

CONCLUSION

RBCs from donors with high levels of nicotine exposure are characterized by increases in basal oxidant stress and decreases in osmotic hemolysis. These findings indicate the need for future clinical studies aimed at addressing the impact of smoking and other sources of nicotine (e.g., nicotine patches, snuff, vaping, secondhand tobacco smoke) on RBC storage quality and transfusion efficacy.

Ethyl glucuronide, a marker of alcohol consumption, correlates with metabolic markers of oxidant stress but not with hemolysis in stored red blood cells from healthy blood donors

BACKGROUND

Red blood cell (RBC) storage in the blood bank is associated with the progressive accumulation of oxidant stress. While the mature erythrocyte is well equipped to cope with such stress, recreative habits like alcohol consumption may further exacerbate the basal level of oxidant stress and contribute to the progress of the storage lesion.

STUDY DESIGN AND METHODS

RBC levels of ethyl glucuronide, a marker of alcohol consumption, were measured via ultra-high-pressure liquid chromatography coupled with high-resolution mass spectrometry. Analyses were performed on 599 samples from the recalled donor population at Storage Days 10, 23, and 42 (n = 250), as part of the REDS-III RBC-Omics (Recipient Epidemiology Donor Evaluation Study III Red Blood Cell-Omics) study. This cohort consisted of the 5th and 95th percentile of donors with extreme hemolytic propensity out of the original cohort of 13,403 subjects enrolled in the REDS-III RBC Omics study. Ehtyl glucuronide levels were thus correlated to global metabolomics and lipidomics analyses and RBC hemolytic propensity.

RESULTS

Ethyl glucuronide levels were positively associated with oxidant stress markers, including glutathione consumption and turnover, methionine oxidation, S-adenosylhomocysteine accumulation, purine oxidation, and transamination markers. Decreases in glycolysis and energy metabolism, the pentose phosphate pathway and ascorbate system were observed in those subjects with the highest levels of ethyl glucuronide, though hemolysis values were comparable between groups.

CONCLUSION

Though preliminary, this study is suggestive that markers of alcohol consumption are associated with increases in oxidant stress and decreases in energy metabolism with no significant impact on hemolytic parameters in stored RBCs from healthy donor volunteers.

Patient Blood Management: transfusion appropriateness in the post-operative period

BACKGROUND

Within the context of Patient Blood Management (PBM) policy for the peri-operative period, the transfusion medicine unit of our institution adopted a series of strategies to support and enhance red blood cell (RBC) transfusion best practices. This study aimed to evaluate the appropriateness of RBC transfusion therapy in the post-operative period, before and after starting a multifactorial PBM policy.

MATERIALS AND METHODS

A 2-phase observational study was conducted on patients who underwent major surgery. The study was designed as follows: 3 months of preliminary audit, followed by multifactorial PBM policy, and a final audit. The policy comprised seminars, teaching lessons, periodic consultations and the insertion of Points of Care. RBC transfusion appropriateness was evaluated in both audits.

RESULTS

The preliminary audit, performed on 168 patients, showed that 37.7% of the patients were appropriately transfused. The final audit, performed on 205 patients, indicated a significant increase of RBC transfusion appropriateness to 65.4%.

DISCUSSION

In our experience, our multifactorial PBM policy improved the RBC transfusion appropriateness in the post-operative period. We believe that our multifactorial PBM policy, which comprises the insertion of Points of Care, supported the healthcare workers in the transfusion decision-making process. This enhancement of transfusion appropriateness implies clinical and managerial advantages, such as reduced transfusion-related risks, optimisation of health care resources, and reduction in costs.

Vesiculation of Red Blood Cells in the Blood Bank: A Multi-Omics Approach towards Identification of Causes and Consequences

Microvesicle generation is an integral part of the aging process of red blood cells in vivo and in vitro. Extensive vesiculation impairs function and survival of red blood cells after transfusion, and microvesicles contribute to transfusion reactions. The triggers and mechanisms of microvesicle generation are largely unknown. In this study, we combined morphological, immunochemical, proteomic, lipidomic, and metabolomic analyses to obtain an integrated understanding of the mechanisms underlying microvesicle generation during the storage of red blood cell concentrates. Our data indicate that changes in membrane organization, triggered by altered protein conformation, constitute the main mechanism of vesiculation, and precede changes in lipid organization. The resulting selective accumulation of membrane components in microvesicles is accompanied by the recruitment of plasma proteins involved in inflammation and coagulation. Our data may serve as a basis for further dissection of the fundamental mechanisms of red blood cell aging and vesiculation, for identifying the cause-effect relationship between blood bank storage and transfusion complications, and for assessing the role of microvesicles in pathologies affecting red blood cells.

Effects of aged stored autologous red blood cells on human plasma metabolome

Cold storage of blood for 5 to 6 weeks has been shown to impair endothelial function after transfusion and has been associated with measures of end-organ dysfunction. Although the products of hemolysis, such as cell-free plasma hemoglobin, arginase, heme, and iron, in part mediate these effects, a complete analysis of transfused metabolites that may affect organ function has not been evaluated to date. Blood stored for either 5 or 42 days was collected from 18 healthy autologous volunteers, prior to and after autologous transfusion into the forearm circulation, followed by metabolomics analyses. Significant metabolic changes were observed in the plasma levels of hemolytic markers, oxidized purines, plasticizers, and oxidized lipids in recipients of blood stored for 42 days, compared with 5 days. Notably, transfusion of day 42 red blood cells (RBCs) increased circulating levels of plasticizers (diethylhexyl phthalate and derivatives) by up to 18-fold. Similarly, transfusion of day 42 blood significantly increased circulating levels of proinflammatory oxylipins, including prostaglandins, hydroxyeicosatrienoic acids (HETEs), and dihydroxyoctadecenoic acids. Oxylipins were the most significantly increasing metabolites (for 9-HETE: up to ∼41-fold, P = 3.7e-06) in day 42 supernatants. Measurements of arginine metabolism confirmed an increase in arginase activity at the expense of nitric oxide synthesis capacity in the bloodstream of recipients of day 42 blood, which correlated with measurements of hemodynamics. Metabolic changes in stored RBC supernatants impact the plasma metabolome of healthy transfusion recipients, with observed increases in plasticizers, as well as vasoactive, pro-oxidative, proinflammatory, and immunomodulatory metabolites after 42 days of storage.

Effects of red blood cell (RBC) transfusion on sickle cell disease recipient plasma and RBC metabolism

BACKGROUND

Exchange transfusion is a mainstay in the treatment of sickle cell anemia. Transfusion recipients with sickle cell disease (SCD) can be transfused over 10 units per therapy, an intervention that replaces circulating sickle red blood cells (RBCs) with donor RBCs. Storage of RBCs makes the intervention logistically feasible. The average storage duration for units transfused at the Duke University Medical Center is approximately 2 weeks, a time window that should anticipate the accumulation of irreversible storage lesion to the RBCs. However, no metabolomics study has been performed to date to investigate the impact of exchange transfusion on recipients' plasma and RBC phenotypes.

STUDY DESIGN AND METHODS

Plasma and RBCs were collected from patients with sickle cell anemia before transfusion and within 5 hours after exchange transfusion with up to 11 units, prior to metabolomics analyses.

RESULTS

Exchange transfusion significantly decreased plasma levels of markers of systemic hypoxemia like lactate, succinate, sphingosine 1-phosphate, and 2-hydroxyglutarate. These metabolites accumulated in transfused RBCs, suggesting that RBCs may act as scavenger/reservoirs. Transfused RBCs displayed higher glycolysis, total adenylate pools, and 2,3-diphosphoglycerate, consistent with increased capacity to deliver oxygen. Plasma levels of acyl-carnitines and amino acids decreased, while fatty acids and potentially harmful phthalates increased upon exchange transfusion.

CONCLUSION

Metabolic phenotypes confirm the benefits of the transfusion therapy in transfusion recipients with SCD and the reversibility of some of the metabolic storage lesion upon transfusion in vivo in 2-week-old RBCs. However, results also suggest that potentially harmful plasticizers are transfused.

Time-Course Investigation of Small Molecule Metabolites in MAP-Stored Red Blood Cells Using UPLC-QTOF-MS

Red blood cells (RBCs) are routinely stored for 35 to 42 days in most countries. During storage, RBCs undergo biochemical and biophysical changes known as RBC storage lesion, which is influenced by alternative storage additive solutions (ASs). Metabolomic studies have been completed on RBCs stored in a number of ASs, including SAGM, AS-1, AS-3, AS-5, AS-7, PAGGGM, and MAP. However, the reported metabolome analysis of laboratory-made MAP-stored RBCs was mainly focused on the time-dependent alterations in glycolytic intermediates during storage. In this study, we investigated the time-course of alterations in various small molecule metabolites in RBCs stored in commercially used MAP for 49 days using ultra-high performance liquid chromatography quadruple time-of-flight mass spectrometry (UPLC-QTOF-MS). These alterations indicated that RBC storage lesion is related to multiple pathways including glycolysis, pentose phosphate pathway, glutathione homeostasis, and purine metabolism. Thus, our findings might be useful for understanding the complexity of metabolic mechanisms of RBCs in vitro aging and encourage the deployment of systems biology methods to blood products in transfusion medicine.

Comparative Evaluation of Biochemical and Hematological Parameters of Pre-Storage Leukoreduction during RBC Storage

Background: Some of the red cell storage lesions (RCSLs) take place during red blood cell (RBC) storage and may reduce the function of these cells dramatically, which mostly caused by residual leucocytes in blood components. This study was planned to observe the biochemical and hematological changes in pre-storage leukoreduced RBC (LR-RBC) compared with unfiltered RBC during in vitro storage. Materials and Methods: Ten unit RBCs were collected, processed and stored according to Iranian standard operating procedure (SOP) of Iranian Blood Transfusion Organization (IBTO). Every unit was split into two equal parts, unfiltered RBC and LR-RBC. Samples were collected and tested on weeks of storage. Biochemical parameters such as lactate dehydrogenase (LDH), lactate concentration and glucose-6-phosphate dehydrogenase (G6PD) enzyme activity were measured by auto-analyzer. In addition, hematology analyzer was used to monitor the change of RBC indices such as (MCV), (MCH) and (MCHC). Results: In this study, both groups showed progressive increase of LDH and lactate levels, and also G6PD activity decreased during storage. Mean of LDH and lactate in unfiltered RBC was significantly increased compared with LR-RBC during all days of storage (p< 0.05). There was statically significant decrease in the G6PD enzyme activity between the two groups and weeks of storage (p< 0.05). However, the RBC indices remained within the expected levels in both groups. Conclusion: LR-RBC and RBC both exhibited RCSL during storage, but LR-RBC is effective in reducing Red cell storage lesion (RCSL) and also improves the quality of stored red blood cells.

Hypoxia modulates the purine salvage pathway and decreases red blood cell and supernatant levels of hypoxanthine during refrigerated storage

Hypoxanthine catabolism in vivo is potentially dangerous as it fuels production of urate and, most importantly, hydrogen peroxide. However, it is unclear whether accumulation of intracellular and supernatant hypoxanthine in stored red blood cell units is clinically relevant for transfused recipients. Leukoreduced red blood cells from glucose-6-phosphate dehydrogenase-normal or -deficient human volunteers were stored in AS-3 under normoxic, hyperoxic, or hypoxic conditions (with oxygen saturation ranging from <3% to >95%). Red blood cells from healthy human volunteers were also collected at sea level or after 1–7 days at high altitude (>5000 m). Finally, C57BL/6J mouse red blood cells were incubated in vitro with ¹³C₁-aspartate or ¹³C₅-adenosine under normoxic or hypoxic conditions, with or without deoxycoformycin, a purine deaminase inhibitor. Metabolomics analyses were performed on human and mouse red blood cells stored for up to 42 or 14 days, respectively, and correlated with 24 h post-transfusion red blood cell recovery. Hypoxanthine increased in stored red blood cell units as a function of oxygen levels. Stored red blood cells from human glucose-6-phosphate dehydrogenase-deficient donors had higher levels of deaminated purines. Hypoxia in vitro and in vivo decreased purine oxidation and enhanced purine salvage reactions in human and mouse red blood cells, which was partly explained by decreased adenosine monophosphate deaminase activity. In addition, hypoxanthine levels negatively correlated with post-transfusion red blood cell recovery in mice and – preliminarily albeit significantly - in humans. In conclusion, hypoxanthine is an in vitro metabolic marker of the red blood cell storage lesion that negatively correlates with post-transfusion recovery in vivo. Storage-dependent hypoxanthine accumulation is ameliorated by hypoxia-induced decreases in purine deamination reaction rates.

Mesenchymal stromal cells can be applied to red blood cells storage as a kind of cellular additive

During storage in blood banks, red blood cells (RBCs) undergo the mechanical and metabolic damage, which may lead to the diminished capacity to deliver oxygen. At high altitude regions, the above-mentioned damage may get worse. Thus, more attention should be paid to preserve RBCs when these components need transfer from plain to plateau regions. Recently, we found that mesenchymal stromal cells (MSCs) could rescue from anemia, and MSCs have been demonstrated in hematopoietic stem cells (HSCs) transplantation to reconstitute hematopoiesis in vivo by us. Considering the functions and advantages of MSCs mentioned above, we are trying to find out whether they are helpful to RBCs in storage duration at high altitudes. In the present study, we first found that mice MSCs could be preserved in citrate phosphate dextrose adenine-1 (CPDA-1) at 4 ± 2°C for 14 days, and still maintained great viability, even at plateau region. Thus, we attempted to use MSCs as an available supplement to decrease RBCs lesion during storage. We found that MSCs were helpful to support RBCs to maintain biochemical parameters and kept RBCs function well on relieving anemia in an acute hemolytic murine model. Therefore, our investigation developed a method to get a better storage of RBCs through adding MSCs, which may be applied in RBCs storage as a kind of cellular additive into preservation solution.

A three-minute method for high-throughput quantitative metabolomics and quantitative tracing experiments of central carbon and nitrogen pathways

RATIONALE

The implementation of mass spectrometry (MS)-based metabolomics is advancing many areas of biomedical research. The time associated with traditional chromatographic methods for resolving metabolites prior to mass analysis has limited the potential to perform large-scale, highly powered metabolomics studies and clinical applications.

METHODS

Here we describe a three-minute method for the rapid profiling of central metabolic pathways through UHPLC/MS, tracing experiments in vitro and in vivo, and targeted quantification of compounds of interest using spiked in heavy labeled standards.

RESULTS

This method has shown to be linear, reproducible, selective, sensitive, and robust for the semi-targeted analysis of central carbon and nitrogen metabolism. Isotopically labeled internal standards are used for absolute quantitation of steady-state metabolite levels and de novo synthesized metabolites in tracing studies. We further propose exploratory applications to biofluids, cell and tissue extracts derived from relevant biomedical/clinical samples.

CONCLUSIONS

While limited to the analysis of central carbon and nitrogen metabolism, this method enables the analysis of hundreds of samples per day derived from diverse biological matrices. This approach makes it possible to analyze samples from large patient populations for translational research, personalized medicine, and clinical metabolomics applications. Copyright © 2017 John Wiley & Sons, Ltd.

Whole Blood Metabolomics by 1H NMR Spectroscopy Provides a New Opportunity To Evaluate Coenzymes and Antioxidants

Conventional human blood metabolomics employs serum or plasma and provides a wealth of metabolic information therein. However, this approach lacks the ability to measure and evaluate important metabolites such as coenzymes and antioxidants that are present at high concentrations in red blood cells. As an important alternative to serum/plasma metabolomics, we show here that a simple 1H NMR experiment can simultaneously measure coenzymes and antioxidants in extracts of whole human blood, in addition to the nearly 70 metabolites that were shown to be quantitated in serum/plasma recently [ Anal. Chem. 2015 , 87 , 706 - 715 ]. Coenzymes of redox reactions: oxidized/reduced nicotinamide adenine dinucleotide (NAD+ and NADH) and nicotinamide adenine dinucleotide phosphate (NADP+ and NADPH); coenzymes of energy including adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP); and antioxidants, the sum of oxidized and reduced glutathione (GSSG and GSH) can be measured with essentially no additional effort. A new method was developed for detecting many of these unstable species without affecting other blood/blood plasma metabolites. The identities of coenzymes and antioxidants in blood NMR spectra were established combining 1D/2D NMR techniques, chemical shift databases, pH measurements and, finally, spiking with authentic compounds. This is the first study to report identification of major coenzymes and antioxidants and quantify them, simultaneously, with the large pool of other metabolites in human blood using NMR spectroscopy. Considering that the levels of coenzymes and antioxidants represent a sensitive measure of cellular functions in health and numerous diseases, the NMR method presented here potentially opens a new chapter in the metabolomics of blood.

Omics markers of the red cell storage lesion and metabolic linkage

The introduction of omics technologies in the field of Transfusion Medicine has significantly advanced our understanding of the red cell storage lesion. While the clinical relevance of such a lesion is still a matter of debate, quantitative and redox proteomics approaches, as well quantitative metabolic flux analysis and metabolic tracing experiments promise to revolutionise our understanding of the role of blood processing strategies, inform the design and testing of novel additives or technologies (such as pathogen reduction), and evaluate the clinical relevance of donor and recipient biological variability with respect to red cell storability and transfusion outcomes. By reviewing existing literature in this rapidly expanding research endeavour, we highlight for the first time a correlation between metabolic markers of the red cell storage age and protein markers of haemolysis. Finally, we introduce the concept of metabolic linkage, i.e. the appreciation of a network of highly correlated small molecule metabolites which results from biochemical constraints of erythrocyte metabolic enzyme activities. For the foreseeable future, red cell studies will advance Transfusion Medicine and haematology by addressing the alteration of metabolic linkage phenotypes in response to stimuli, including, but not limited to, storage additives, enzymopathies (e.g. glucose 6-phosphate dehydrogenase deficiency), hypoxia, sepsis or haemorrhage.

A Comparative Study of the Effect of Leukoreduction and Pre-storage Leukodepletion on Red Blood Cells during Storage

Blood transfusion is a fundamental therapy in numerous pathological conditions. Regrettably, many clinical reports describe adverse transfusion's drawbacks due to red blood cells alterations during storage. Thus, the possibility for a blood bank to ameliorate the quality of the erythrocyte concentrates units is crucial to improve clinical results and reduce transfusion adverse occurrences. Leukodepletion is a pre-storage treatment recognized to better preserve the quality of red blood cells with respect to leukoreduction. Aim of this work is to unravel the biochemical and biophysical basis that sustain the good clinical outcomes associated to the use of leukodepleted erythrocytes units. Erythrocytes concentrates were prepared as leukoreduced (n = 8) and pre-storage leukodepleted (n = 8) and then studied during 6 weeks in blood bank conditions. Overall, the data indicate that leukodepletion not only provide red blood cells with an appropriate amount of nutrients for a longer time but also selects red blood cells characterized by a more resilient plasma membrane fit to prolong their viability. We believe these results will stimulate new ideas to further optimize the current storage protocols.

Metabolomics in transfusion medicine

Biochemical investigations on the regulatory mechanisms of red blood cell (RBC) and platelet (PLT) metabolism have fostered a century of advances in the field of transfusion medicine. Owing to these advances, storage of RBCs and PLT concentrates has become a lifesaving practice in clinical and military settings. There, however, remains room for improvement, especially with regard to the introduction of novel storage and/or rejuvenation solutions, alternative cell processing strategies (e.g., pathogen inactivation technologies), and quality testing (e.g., evaluation of novel containers with alternative plasticizers). Recent advancements in mass spectrometry-based metabolomics and systems biology, the bioinformatics integration of omics data, promise to speed up the design and testing of innovative storage strategies developed to improve the quality, safety, and effectiveness of blood products. Here we review the currently available metabolomics technologies and briefly describe the routine workflow for transfusion medicine-relevant studies. The goal is to provide transfusion medicine experts with adequate tools to navigate through the otherwise overwhelming amount of metabolomics data burgeoning in the field during the past few years. Descriptive metabolomics data have represented the first step omics researchers have taken into the field of transfusion medicine. However, to up the ante, clinical and omics experts will need to merge their expertise to investigate correlative and mechanistic relationships among metabolic variables and transfusion-relevant variables, such as 24-hour in vivo recovery for transfused RBCs. Integration with systems biology models will potentially allow for in silico prediction of metabolic phenotypes, thus streamlining the design and testing of alternative storage strategies and/or solutions.

Red blood cell storage in additive solution-7 preserves energy and redox metabolism: a metabolomics approach

BACKGROUND

Storage and transfusion of red blood cells (RBCs) has a huge medical and economic impact. Routine storage practices can be ameliorated through the implementation of novel additive solutions (ASs) that tackle the accumulation of biochemical and morphologic lesion during routine cold liquid storage in the blood bank, such as the recently introduced alkaline solution AS-7. Here we hypothesize that AS-7 might exert its beneficial effects through metabolic modulation during routine storage.

STUDY DESIGN AND METHODS

Apheresis RBCs were resuspended either in control AS-3 or experimental AS-7, before ultrahigh-performance liquid chromatography-mass spectrometry metabolomics analysis.

RESULTS

Unambiguous assignment and relative quantitation was achieved for 229 metabolites. AS-3 and AS-7 results in many similar metabolic trends over storage, with AS-7 RBCs being more metabolically active in the first storage week. AS-7 units had faster fueling of the pentose phosphate pathway, higher total glutathione pools, and increased flux through glycolysis as indicated by higher levels of pathway intermediates. Metabolite differences are especially observed at 7 days of storage, but were still maintained throughout 42 days.

CONCLUSION

AS-7 formulation (chloride free and bicarbonate loading) appears to improve energy and redox metabolism in stored RBCs in the early storage period, and the differences, though diminished, are still appreciable by Day 42. Energy metabolism and free fatty acids should be investigated as potentially important determinants for preservation of RBC structure and function. Future studies will be aimed at identifying metabolites that correlate with in vitro and in vivo circulation times.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

Metabolomics of AS-5 RBC supernatants following routine storage

BACKGROUND AND OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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