Stored red blood cells: a changing universe waiting for its map(s)

Assessment of amino acids and metabolites in the supernatant of stored concentrates blood from sickle cell trait (SCT) and reference (non-SCT) donors

BACKGROUND AND OBJECTIVES

Sickle cell trait (SCT) persons are significant donors, and discarding these blood units reduces their supplies, mainly in the third-world countries. This work focused on 12 metabolites associated with the red blood cell (RBC) storage lesion and 23 amino acids in the supernatants of packed RBC units from SCT and reference (non-SCT) donors stored in the same conditions.

MATERIALS AND METHODS

All samples of RBC concentrates were collected and separated from the storage of Colsan (Beneficient Association of Blood Collection), where they were routinely processed and separated as packed RBC units and stored in the refrigerator (2°-6°C). The supernatant samples of each packed RBC bag were separated by centrifugation at days 1, 7, 14, 21, 28 and 35 of storage and kept at -80°C till the metabolite analysis together.

RESULTS

The quantitation of metabolites and amino acids examined in the supernatant of SCT and reference donors showed no statistical differences along the cold storage. Lactic acid and malic acid releases occur in three phases during RBC storage. Basic and acid amino acids and corresponding amides have low and stable values during the first 14 days of storage, followed by a steep increase.

CONCLUSION

Our metabolomic results give elements that seem not to contraindicate the transfusion of RBC with SCT, besides its more structural fragility.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

DISCUSSION

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

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

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

Risk Assessment of Red Cell Transfusion in Congenital Heart Disease

Background  The storage time of packed red blood cells (pRBC) is an indicator of change in the product's pH, potassium, and lactate levels. Blood–gas analysis is a readily available bedside tool on every intensive care ward to measure these factors prior to application, thus facilitating a calculated decision on a transfusion's quantity and duration.

Our first goal is to assess the impact of storage time on pH, potassium, and lactate levels in pRBC. The influence of those parameters in the transfused children will then be evaluated.

Methods  In this retrospective study, we conducted blood–gas analyses of pRBC units before they were administered over 4 hours to neonates, infants, and children in our pediatric cardiac intensive care ward. All patients underwent regular blood–gas analyses themselves, before and after transfusion.

Results  We observed a highly significant correlation between the storage time of pRBC units and a drop in pH, as well as an increase in potassium and lactate of stored red cells ( p < 0.0001). Median age of recipients with a complete blood–gas dataset was 0.1 (interquartile range [IQR] = 0.0–0.7) years; median pRBC storage duration was 6 (IQR = 5–8) days. Further analyses showed no statistically significant effect on children's blood gases within 4 hours after transfusion, even after stratifying for pRBC storage time ≤7 days and >7 days.

Conclusion  Stored red blood cells show a rapid decrease in pH and increase in potassium and lactate. Slow transfusion of these units had no adverse effects on the recipients' pH, potassium, and lactate levels.

Hemocompatibility and Hemolytic Effects of Functionalized Nanoparticles on Red Blood Cells: A Recent Review Study

In this paper (from 2010 to 2020), the effects of polymeric, metallic and nonmetallic nanoparticles on red blood cells’ hemocompatibility were investigated for the first time. Here, we have considered the latest findings which can help to improve the hemocompatibility of RBCs. It is important to maintain the quality of red blood cells for improving the hemocompatibility because blood products directly affect the health of patients after blood transfusion. Although RBCs can be stored for up to 42 days at 2–6∘C, hypothermic storage lesions (HSLs) are very common in these products. This problem affects the quality of RBC products. Thus, it is necessary to modify the surface molecules of RBCs during storage time to reduce HSLs and alloimmunization complications. Therefore, we reviewed the reported effects of polymeric, metallic and carbon-based nanoparticles on RBCs between 2010 and 2020. The results of our study have shown that the use of negatively charged dendrimers, unsaturated/uncharged liposomes, and PEGylated forms of NPs and RBCs are the best approaches to improve the hemocompatibility conditions of red blood cells. However, large cationic dendrimers, liposomes composed of saturated lipid with long acyl chain, and cationic chitosan nanoparticles have less RBC compatibility. In addition, polymeric nanoparticles have more capacity for surface modification, which makes it possible to make more hemocompatible derivatives. Among metallic nanoparticles, gold and iron nanoparticles were more RBC compatible. However, the smaller size, higher concentration and longer exposure time of these nanoparticles can induce hemolysis and morphological changes in RBCs. On the other side, nonmetallic nanoparticles mostly had poor RBC compatibility, but their effects on RBCs strongly depended on their concentration and physicochemical properties and could be controllable. As a result, the use of polyethylene glycol (PEG), gold, polymeric, and iron nanoparticles in the design of protocols to maintain the survival, structure and activity of red blood cells for improving hemocompatibility can be more effective.

Quantifying dynamic range in red blood cell energetics: Evidence of progressive energy failure during storage

BACKGROUND

During storage, red blood cells (RBCs) undergo significant biochemical and morphologic changes, referred to collectively as the "storage lesion". It was hypothesized that these defects may arise from disrupted oxygen-based regulation of RBC energy metabolism, with resultant depowering of intrinsic antioxidant systems.

STUDY DESIGN AND METHODS

As a function of storage duration, the dynamic range in RBC metabolic response to three models of biochemical oxidant stress (methylene blue, hypoxanthine/xanthine oxidase, and diamide) was assessed, comparing glycolytic flux by NMR and UHPLC-MS methodologies. Blood was processed/stored under standard conditions (AS-1 additive solution) with leukoreduction. Over a 6-week period, RBC metabolic and antioxidant status were assessed at baseline and following exposure to the three biochemical oxidant models. Comparison was made of glycolytic flux (¹ H-NMR tracking of [2-¹³ C]-glucose and metabolomic phenotyping with [1,2,3-¹³ C₃ ] glucose), reducing equivalent (NADPH/NADP⁺ ) recycling, and thiol-based (GSH/GSSG) antioxidant status.

RESULTS

As a function of storage duration, we observed the following: (1) a reduction in baseline hexose monophosphate pathway (HMP) flux, the sole pathway responsible for the regeneration of the essential reducing equivalent NADPH; with (2) diminished stress-based dynamic range in both overall glycolytic as well as proportional HMP flux. In addition, progressive with storage duration, RBCs showed (3) constraint in reducing equivalent (NADPH) recycling capacity, (4) loss of thiol based (GSH) recycling capacity, and (5) dysregulation of metabolon assembly at the cytoplasmic domain of Band 3 membrane protein (cdB3).

CONCLUSION

Blood storage disturbs normal RBC metabolic control, depowering antioxidant capacity and enhancing vulnerability to oxidative injury.

Hypoxic storage of erythrocytes slows down storage lesions and prolongs shelf-life

Conventional storage conditions of erythrocytes cause storage lesions. We propose that hypoxic storage conditions, involving removal of oxygen and replacement with helium, the changes in stored erythrocytes under hypoxic condition were observed and assessed. Erythrocytes were divided into two equal parts, then stored in conventional and hypoxic conditions, separately. Blood gas analysis, hemorheology, and hemolysis were performed once a week. Energy metabolism and membrane damage were monitored by enzyme-linked immunosorbent assay. Phosphatidylserine exposure was measured by flow cytometry. P₅₀ was measured and the oxygen dissociation curve (ODC) plotted accordingly. Erythrocyte morphology was observed microscopically. In the 9th week of storage, the hemolysis of the hypoxia group was 0.7%; lower (p < .05) than that of the control group and still below the threshold of quality requirements. The dissolved oxygen and pO₂ were only 1/4 of that in the control group (p < .01); the adenosine triphosphate, glucose, and lactic acid levels were decreased (p < .05), while the 2,3-diphosphoglycerate levels were increased relative to that in the control group (p < .01). There were no statistically significant differences in membrane damage, deformability, and aggregation between the two groups. In addition, the ODC of the two groups was shifted to the left but this difference was not statistically different. Basically similar to the effect of completely anaerobic conditions. Erythrocytes stored under hypoxic conditions could maintain a relatively stable state with a significant decrease in hemolysis, reduction of storage lesions, and an increase in shelf-life.

Effect of storage period of red blood cell suspensions on helper T-cell subpopulations

BACKGROUND

The aim of this study was to investigate the immunological alterations that occur during the storage of erythrocyte suspensions which may lead to transfusion-related immunomodulation following allogeneic blood transfusion.

MATERIALS AND METHODS

One part of the erythrocyte suspensions obtained from donors was leucoreduced while the other part was not. The leucoreduced (LR) and non-leucoreduced (NL) erythrocyte suspensions were then further divided into three equal amounts which were stored for 0, 21 or 42 days prior to measurements, by enzyme-linked immunosorbent assays, of cytokine levels in their supernatants. T-helper (Th) lymphocyte subgroups and gene expression were analysed in the NL erythrocyte suspensions by flow cytometry and real-time polymerase chain reaction, respectively. Results were compared to those of storage day 0.

RESULTS

By day 21, the number of Th2 cells had increased significantly and the numbers of Th1, Th22 and Treg cells had decreased significantly in the NL erythrocyte suspensions. On day 42 the numbers of Th2 and Treg cells in the NL suspensions were significantly increased while the number of Th1 cells was significantly decreased. The levels of transcription factors (TBX21, GATA3, and SPI.1) were significantly decreased on days 21 and 42, and AHR, FOXP3 and RORC2 levels were significantly increased on day 42 in NL erythrocyte suspensions. The decrease in interleukin-22 and increase in transforming growth factor-β levels found in NL erythrocyte suspensions on day 21 were statistically significant. Elevated levels of interleukin-17A were found in both LR and NL erythrocyte suspensions on day 42.

DISCUSSION

Our results suggest that allogeneic leucocytes and cytokines may play significant roles in the development of transfusion-related immunomodulation.

Red blood cells ageing markers: a multi-parametric analysis

BACKGROUND

Red blood cells collected in citrate-phosphate-dextrose can be stored for up to 42 days at 4 °C in saline-adenine-glucose-mannitol additive solution. During this controlled, but nevertheless artificial, ex vivo ageing, red blood cells accumulate lesions that can be reversible or irreversible upon transfusion. The aim of the present study is to follow several parameters reflecting cell metabolism, antioxidant defences, morphology and membrane dynamics during storage.

MATERIALS AND METHODS

Five erythrocyte concentrates were followed weekly during 71 days. Extracellular glucose and lactate concentrations, total antioxidant power, as well as reduced and oxidised intracellular glutathione levels were quantified. Microvesiculation, percentage of haemolysis and haematologic parameters were also evaluated. Finally, morphological changes and membrane fluctuations were recorded using label-free digital holographic microscopy.

RESULTS

The antioxidant power as well as the intracellular glutathione concentration first increased, reaching maximal values after one and two weeks, respectively. Irreversible morphological lesions appeared during week 5, where discocytes began to transform into transient echinocytes and finally spherocytes. At the same time, the microvesiculation and haemolysis started to rise exponentially. After six weeks (expiration date), intracellular glutathione was reduced by 25%, reflecting increasing oxidative stress. The membrane fluctuations showed decreased amplitudes during shape transition from discocytes to spherocytes.

DISCUSSION

Various types of lesions accumulated at different chemical and cellular levels during storage, which could impact their in vivo recovery after transfusion. A marked effect was observed after four weeks of storage, which corroborates recent clinical data. The prolonged follow-up period allowed the capture of deep storage lesions. Interestingly, and as previously described, the severity of the changes differed among donors.

Morphology, membrane nanostructure and stiffness for quality assessment of packed red blood cells

Transfusion of packed red blood cells (PRBC) to patients in critical states is often accompanied by post-transfusion complications. This may be related with disturbance of properties of PRBC and their membranes during long-term storage in the hemopreservative solution. The purpose of our work is the study of transformation of morphology, membranes stiffness and nanostructure for assessment of PRBC quality, in vitro. By atomic force microscopy we studied the transformation of cell morphology, the appearance of topological nanodefects of membranes and by atomic force spectroscopy studied the change of membrane stiffness during 40 days of storage of PRBC. It was shown that there is a transition period (20–26 days), in which we observed an increase in the Young’s modulus of the membranes 1.6–2 times and transition of cells into irreversible forms. This process was preceded by the appearance of topological nanodefects of membranes. These parameters can be used for quality assessment of PRBC and for improvement of transfusion rules.

Attenuation of Red Blood Cell Storage Lesions with Vitamin C

Stored red blood cells (RBCs) undergo oxidative stress that induces deleterious metabolic, structural, biochemical, and molecular changes collectively referred to as “storage lesions”. We hypothesized that vitamin C (VitC, reduced or oxidized) would reduce red cell storage lesions, thus prolonging their storage duration. Whole-blood-derived, leuko-reduced, SAGM (saline-adenine-glucose-mannitol)-preserved RBC concentrates were equally divided into four pediatric storage bags and the following additions made: (1) saline (saline); (2) 0.3 mmol/L reduced VitC (Lo VitC); (3) 3 mmol/L reduced VitC (Hi VitC); or (4) 0.3 mmol/L oxidized VitC (dehydroascorbic acid, DHA) as final concentrations. Biochemical and rheological parameters were serially assessed at baseline (prior to supplementation) and Days 7, 21, 42, and 56 for RBC VitC concentration, pH, osmotic fragility by mechanical fragility index, and percent hemolysis, LDH release, glutathione depletion, RBC membrane integrity by scanning electron microscopy, and Western blot for β-spectrin. VitC exposure (reduced and oxidized) significantly increased RBC antioxidant status with varying dynamics and produced trends in reduction in osmotic fragility and increases in membrane integrity. Conclusion: VitC partially protects RBC from oxidative changes during storage. Combining VitC with other antioxidants has the potential to improve long-term storage of RBC.

Effects of stiffness and volume on the transit time of an erythrocyte through a slit

By using a fully coupled fluid-cell interaction model, we numerically simulate the dynamic process of a red blood cell passing through a slit driven by an incoming flow. The model is achieved by combining a multiscale model of the composite cell membrane with a boundary element fluid dynamics model based on the Stokes flow assumption. Our concentration is on the correlation between the transit time (the time it takes to finish the whole translocation process) and different conditions (flow speed, cell orientation, cell stiffness, cell volume, etc.) that are involved. According to the numerical prediction (with some exceptions), the transit time rises as the cell is stiffened. It is also highly sensitive to volume increase inside the cell. In general, even slightly swollen cells (i.e., the internal volume is increased while the surface area of the cell kept unchanged) travel dramatically slower through the slit. For these cells, there is also an increased chance of blockage.

Donor-variation effect on red blood cell storage lesion: A close relationship emerges

Although the molecular pathways leading to the progressive deterioration of stored red blood cells (RBC storage lesion) and the clinical relevance of storage-induced changes remain uncertain, substantial donor-specific variability in RBC performance during storage, and posttransfusion has been established ("donor-variation effect"). In-bag hemolysis and numerous properties of the RBC units that may affect transfusion efficacy have proved to be strongly donor-specific. Donor-variation effect may lead to the production of highly unequal blood labile products even when similar storage strategy and duration are applied. Genetic, undiagnosed/subclinical medical conditions and lifestyle factors that affect RBC characteristics at baseline, including RBC lifespan, energy metabolism, and sensitivity to oxidative stress, are all likely to influence the storage capacity of individual donors' cells, although not evident by the donor's health or hematological status at blood donation. Consequently, baseline characteristics of the donors, such as membrane peroxiredoxin-2 and serum uric acid concentration, have been proposed as candidate biomarkers of storage quality. This review article focuses on specific factors that might contribute to the donor-variation effect and emphasizes the emerging need for using omics-based technologies in association with in vitro and in vivo transfusion models and clinical trials to discover biomarkers of storage quality and posttransfusion recovery in donor blood.

Prospects of curcumin as an additive in storage solutions: a study on erythrocytes

BACKGROUND/AIM

Curcumin, a naturally occurring antioxidant, shows a wide variety of medicinal properties. The possibility of utilizing curcumin as an additive in storage solutions of blood has not been explored. The purpose of this study was to analyze the effect of curcumin on erythrocytes during storage.

MATERIALS AND METHODS

Blood obtained from rats was stored (4 °C) for 20 days in citrate-phosphate-dextrose-adenine-1 solution. Samples were divided into four groups: 1) Controls; 2) Curcumin 10 mM; 3) Curcumin 30 mM; and 4) Curcumin 60 mM. Every fifth day, hemoglobin, superoxide, antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase (GSH-Px)), lipid peroxidation (conjugate dienes and malondialdehyde (MDA)), protein oxidation (advanced oxidation protein products (AOPP) and sulfhydryls (P-SH)), and hemolysis were analyzed.

RESULTS

Hemoglobin was successfully maintained, while superoxide dismutase increased initially and decreased towards the end of storage. Superoxide, catalase, GSH-Px, conjugate dienes, and AOPP were lower in the curcumin groups than they were in the controls. MDA was higher in the curcumin groups than in the controls. P-SH increased in the curcumin groups, while hemolysis increased in all groups.

CONCLUSION

Curcumin maintained hemoglobin and modulated antioxidant enzymes throughout storage. However, curcumin could not protect all proteins and lipids from oxidative damage completely. This study opens up new avenues for using curcumin, in combination with other antioxidants, as a component in storage solutions.

Proteomics of the red blood cell carbonylome during blood banking of erythrocyte concentrates

PURPOSE

Transfusion of red blood cells (RBCs) is a daily medical procedure. Erythrocyte concentrates (ECs) can be stored up to 56 days at 4 °C in saline additive solution mainly composed of adenine and sugar. Such nonphysiological conditions induce the occurrence of storage lesions, such as alterations of metabolism, protein oxidation, and deterioration of rheological properties. Their accumulation tends to decrease the main EC therapeutic property, that is, the oxygenation capacity. Protein carbonylation is a marker of oxidative stress and aging, and its occurrence during RBC storage was earlier characterized as a time-dependent and cellular compartment dependent modification.

EXPERIMENTAL DESIGN

Three ECs from independent donations were followed. The carbolynome was here characterized in soluble and membrane extracts (n-dodecyl β-D-maltoside-based extraction buffer) of RBCs stored for 6, 27, and 41 days, through biotin hydrazide derivatization, biotin-avidin affinity purification, SDS-PAGE separation, and LC-MS/MS analyses.

RESULTS

A total of 142 and 20 proteins were identified as carbonylated in soluble and membrane extracts, respectively. Particularly, a time-dependent evolution of 26.8% of the soluble carbonylome was observed.

CONCLUSIONS AND CLINICAL RELEVANCE

Affected cellular mechanisms involve antioxidant defenses, metabolism pathways, and proteasomal degradation. To better store RBCs those functions have to be preserved, which opens new routes of investigation in transfusion medicine.

Impact of the age of stored blood on trauma patient mortality: a systematic review

BACKGROUND

The impact of the age of stored red blood cells on mortality in patients sustaining traumatic injuries requiring transfusion of blood products is unknown. The objective of this systematic review was to identify and describe the available literature on the use of older versus newer blood in trauma patient populations.

METHODS

We searched PubMed, Embase, Lilac and the Cochrane Database for published studies comparing the transfusion of newer versus older red blood cells in adult patients sustaining traumatic injuries. Studies included for review reported on trauma patients receiving transfusions of packed red blood cells, identified the age of stored blood that was transfused and reported patient mortality as an end point. We extracted data using a standardized form and assessed study quality using the Newcastle-Ottawa Scale.

RESULTS

Seven studies were identified (6780 patients) from 3936 initial search results. Four studies reported that transfusion of older blood was independently associated with increased mortality in trauma patients, while 3 studies did not observe any increase in patient mortality with the use of older versus newer blood. Three studies associated the transfusion of older blood with adverse patient outcomes, including longer stay in the intensive care unit, complicated sepsis, pneumonia and renal dysfunction. Studies varied considerably in design, volumes of blood transfused and definitions applied for old and new blood..

CONCLUSION

The impact of the age of stored packed red blood cells on mortality in trauma patients is inconclusive. Future investigations are warranted.

Biochemistry of storage lesions of red cell and platelet concentrates: A continuous fight implying oxidative/nitrosative/phosphorylative stress and signaling

The mechanisms responsible for the reduced lifespan of transfused red blood cells (RBCs) and platelets (PLTs) are still under investigation, however one explanation refers to the detrimental biochemical changes occurring during ex vivo storage of these blood products. A myriad of historical and more recent studies has contributed to advance our understanding of storage lesion. Without any doubts, proteomics had great impact on transfusion medicine by profiling the storage-dependent changes in the total detectable protein pool of both RBCs and PLTs. This review article focuses on the role of oxidative/nitrosative stress in developing RBC and PLT storage lesions, with a special glance at its biochemistry and cross-talk with phosphorylative signal transduction. In this sense, we enlighten the potential contribution of new branches of proteomics in identifying novel points of intervention for the improvement of blood product quality.

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.

Maintaining Specimen Integrity for G6PD Screening by Cytofluorometric Assays

Cytochemical staining remains an efficient way of identifying females who are heterozygous for the X chromosome-linked glucose-6-phosphate dehydrogenase (G6PD) gene. G6PD is highly polymorphic with certain alleles resulting in low intracellular G6PD activity in red blood cells. Low intracellular G6PD activity is associated with a risk of severe hemolysis when exposed to an oxidative stress such as fava beans, certain drugs and infections. Heterozygous females express the enzyme from both X-chromosome alleles resulting in two red blood cell populations each with G6PD enzyme characteristics representative of each allele; for example, normal and deficient. Cytochemical staining is the only way to determine the relative representation of each allele in red blood cells, a feature that is critical when assessing the risk for severe hemolysis when exposed to an oxidant such as the anti-malarial drug primaquine. This letter discusses red blood cell integrity with respect to the cytofluorometric assays for G6PD activity. An approach to making this test more robust is suggested. The approach makes this test more reliable and extends its use to a broader range of blood specimens.

Targeted quantitative phosphoproteomic analysis of erythrocyte membranes during blood bank storage

One of the hallmarks of blood bank stored red blood cells (RBCs) is the irreversible transition from a discoid to a spherocyte-like morphology with membrane perturbation and cytoskeleton disorders. Therefore, identification of the storage-associated modifications in the protein-protein interactions between the cytoskeleton and the lipid bilayer may contribute to enlighten the molecular mechanisms involved in the alterations of mechanical properties of stored RBCs. Here we report the results obtained analyzing RBCs after 0, 21 and 35 days of storage under standard blood banking conditions by label free mass spectrometry (MS)-based experiments. We could quantitatively measure changes in the phosphorylation level of crucial phosphopeptides belonging to β-spectrin, ankyrin-1, α-adducin, dematin, glycophorin A and glycophorin C proteins. Data have been validated by both western blotting and pseudo-Multiple Reaction Monitoring (MRM). Although each phosphopeptide showed a distinctive trend, a sharp increase in the phosphorylation level during the storage duration was observed. Phosphopeptide mapping and structural modeling analysis indicated that the phosphorylated residues localize in protein functional domains fundamental for the maintenance of membrane structural integrity. Along with previous morphological evidence acquired by electron microscopy, our results seem to indicate that 21-day storage may represent a key point for the molecular processes leading to the erythrocyte deformability reduction observed during blood storage. These findings could therefore be helpful in understanding and preventing the morphology-linked mechanisms responsible for the post-transfusion survival of preserved RBCs.

Role of transfused red blood cells for shock and coagulopathy within remote damage control resuscitation

The philosophy of damage control resuscitation (DCR) and remote damage control resuscitation (RDCR) can be summarized by stating that the goal is to prevent death from hemorrhagic shock by "staying out of trouble instead of getting out of trouble." In other words, it is preferred to arrest the progression of shock, rather than also having to reverse this condition after significant tissue damage and organ injury cascades are established. Moreover, to prevent death from exsanguination, a balanced approach to the treatment of both shock and coagulopathy is required. This was military doctrine during World War II, but seemed to be forgotten during the last half of the 20th century. Damage control resuscitation and RDCR have revitalized the approach, but there is still more to learn about the most effective and safe resuscitative strategies to simultaneously treat shock and hemorrhage. Current data suggest that our preconceived notions regarding the efficacy of standard issue red blood cells (RBCs) during the hours after transfusion may be false. Standard issue RBCs may not increase oxygen delivery and may in fact decrease it by disturbing control of regional blood flow distribution (impaired nitric oxide processing) and failing to release oxygen, even when perfusing hypoxic tissue (abnormal oxygen affinity). Standard issue RBCs may assist with hemostasis but appear to have competing effects on thrombin generation and platelet function. If standard issue or RBCs of increased storage age are not optimal, then are there alternatives that will allow for an efficacious and safe treatment of shock while also supporting hemostasis? Studies are required to determine if fresh RBCs less than 7 to 10 days provide an outcome advantage. A resurgence in the study of whole blood stored at 4°C for up to 10 days also holds promise. Two randomized controlled trials in humans have indicated that following transfusion with either whole blood stored at 4°C or platelets stored at 4°C there was less clinical bleeding than when blood was reconstituted with components or when platelets were stored at 22°C. Early reversal of shock is essential to prevent exacerbation of coagulopathy and progression of cell death cascades in patients with severe traumatic injuries. Red blood cell storage solutions have evolved to accommodate the needs of non-critically ill patients yet may not be optimal for patients in hemorrhagic shock. Continued focus on the recognition and treatment of shock is essential for continued improvement in outcomes for patients who require damage control resuscitation and RDCR.

The involvement of cation leaks in the storage lesion of red blood cells

Stored blood components are a critical life-saving tool provided to patients by health services worldwide. Red cells may be stored for up to 42 days, allowing for efficient blood bank inventory management, but with prolonged storage comes an unwanted side-effect known as the "storage lesion", which has been implicated in poorer patient outcomes. This lesion is comprised of a number of processes that are inter-dependent. Metabolic changes include a reduction in glycolysis and ATP production after the first week of storage. This leads to an accumulation of lactate and drop in pH. Longer term damage may be done by the consequent reduction in anti-oxidant enzymes, which contributes to protein and lipid oxidation via reactive oxygen species. The oxidative damage to the cytoskeleton and membrane is involved in increased vesiculation and loss of cation gradients across the membrane. The irreversible damage caused by extensive membrane loss via vesiculation alongside dehydration is likely to result in immediate splenic sequestration of these dense, spherocytic cells. Although often overlooked in the literature, the loss of the cation gradient in stored cells will be considered in more depth in this review as well as the possible effects it may have on other elements of the storage lesion. It has now become clear that blood donors can exhibit quite large variations in the properties of their red cells, including microvesicle production and the rate of cation leak. The implications for the quality of stored red cells from such donors is discussed.

Storing red blood cells with vitamin C and N-acetylcysteine prevents oxidative stress-related lesions: a metabolomics overview

BACKGROUND

Recent advances in red blood cell metabolomics have paved the way for further improvements of storage solutions.

MATERIALS AND METHODS

In the present study, we exploited a validated high performance liquid chromatography-mass spectrometry analytical workflow to determine the effects of vitamin C and N-acetylcysteine supplementation (anti-oxidants) on the metabolome of erythrocytes stored in citrate-phosphate-dextrose saline-adenine-glucose-mannitol medium under blood bank conditions.

RESULTS

We observed decreased energy metabolism fluxes (glycolysis and pentose phosphate pathway). A tentative explanation of this phenomenon could be related to the observed depression of the uptake of glucose, since glucose and ascorbate are known to compete for the same transporter. Anti-oxidant supplementation was effective in modulating the redox poise, through the promotion of glutathione homeostasis, which resulted in decreased haemolysis and less accumulation of malondialdehyde and oxidation by-products (including oxidized glutathione and prostaglandins).

DISCUSSION

Anti-oxidants improved storage quality by coping with oxidative stress at the expense of glycolytic metabolism, although reservoirs of high energy phosphate compounds were preserved by reduced cyclic AMP-mediated release of ATP.

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

BACKGROUND

Blood transfusion is an established therapeutic practice. The characteristics of blood components at different storage times are expected to affect the efficacy of transfusion therapy. Metabolic profiling by nuclear magnetic resonance (NMR) spectroscopy requires little or no sample treatment and allows identification of more than 50 soluble metabolites in a single experiment. The aim of this study was to assess the metabolic behaviour of red blood cells during 42 days of storage in blood bank conditions.

MATERIALS AND METHODS

Red blood cells (RBC), collected from eight healthy male donors, aged 25-50 years, were prepared as prestorage leukoreduced erythrocyte concentrates and stored under standard blood bank conditions. Samples taken at various storage times were separated in two fractions: the supernatant, recovered after centrifugation, and the red blood cell lysate obtained after protein depletion by ultrafiltration. The metabolic profile of the red blood cells was determined from analysis of (1)H-NMR spectra.

RESULTS

The red blood cell supernatant was studied to track the consumption of the preservative additives and to detect and quantify up to 30 metabolites excreted by the erythrocytes. The NMR spectra of the RBC lysate provided complementary information on some biochemical pathways and set the basis for building a time-dependent red blood cell metabolic profile.

DISCUSSION

We proved the analytical power of (1)H-NMR spectroscopy to study red blood cell metabolism under blood bank conditions. A potential biomarker able to provide information on the level of cellular oxidative stress protection was identified. Our data support the hypothesis that a more detailed knowledge of metabolic modifications during storage opens the way to the development of new and more effective protocols for red blood cell conservation and patient-oriented transfusion therapy.

Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome

A goal of the Chromosome-centric Human Proteome Project is to identify all human protein species. With 3844 proteins annotated as "missing", this is challenging. Moreover, proteolytic processing generates new protein species with characteristic neo-N termini that are frequently accompanied by altered half-lives, function, interactions, and location. Enucleated and largely void of internal membranes and organelles, erythrocytes are simple yet proteomically challenging cells due to the high hemoglobin content and wide dynamic range of protein concentrations that impedes protein identification. Using the N-terminomics procedure TAILS, we identified 1369 human erythrocyte natural and neo-N-termini and 1234 proteins. Multiple semitryptic N-terminal peptides exhibited improved mass spectrometric identification properties versus the intact tryptic peptide enabling identification of 281 novel erythrocyte proteins and six missing proteins identified for the first time in the human proteome. With an improved bioinformatics workflow, we developed a new classification system and the Terminus Cluster Score. Thereby we described a new stabilizing N-end rule for processed protein termini, which discriminates novel protein species from degradation remnants, and identified protein domain hot spots susceptible to cleavage. Strikingly, 68% of the N-termini were within genome-encoded protein sequences, revealing alternative translation initiation sites, pervasive endoproteolytic processing, and stabilization of protein fragments in vivo. The mass spectrometry proteomics data have been deposited to ProteomeXchange with the data set identifier <PXD000434>.

Serotonin is a key factor for mouse red blood cell survival

Serotonin (5-HT) is a monoamine originally purified from blood as a vasoactive agent. In nonneuronal tissues, its presence is linked with the expression of tryptophan hydroxylase 1 (TPH1) that catalyzes the rate-limiting step of its synthesis. Targeted disruption in mice of the TPH1 gene results in very low levels of circulating 5-HT. Previous analysis of the TPH1 knockout (TPH1^−/−) mouse revealed that they develop a phenotype of macrocytic anemia with a reduced half-life of their circulating red blood cells (RBC). In this study, to establish whether the observed reduced half-life of TPH1^−/− RBC is an intrinsic or an extrinsic characteristic, we compared their survival to RBC isolated from wild-type mice. Both in vivo and in vitro data converge to demonstrate an extrinsic protective effect of 5-HT since presence of 5-HT in the RBC environment protects RBC from senescence. The protective effect played by 5-HT is not mediated through activation of a classical pharmacological pathway as no 5-HT receptors were detected on isolated RBC. Rather, 5-HT acts as an effective antioxidant since reduction of 5-HT circulating levels are associated with a decrease in the plasma antioxidant capacity. We further demonstrate a link between oxidation and the removal of damaged RBC following transfusion, as supplementation with 5-HT improves RBC post-transfusion survival in a mouse model of blood banking.

The effect of gamma radiation on the lipid profile of irradiated red blood cells

An investigation into the effects of irradiation and of the storage time on aging and quality are a relevant issue to ensure the safety and the efficiency of irradiation in the prevention of transfusion-associated graft-versus-host disease (TA-GVHD). In this work, the biochemical properties and alterations presented by erythrocyte membranes, up to 28-days post-irradiation, with a dose of 25 Gy, were studied as a function of storage and post-irradiation time. There was a considerable variation in the total of phospholipid content, when comparing the control and irradiated samples, mostly from the third day onwards; and at the same time, the effect occurred as a function on the storage time of blood bags. The levels of total cholesterol decreased 3-9 days after irradiation. TBARS levels were increased after irradiation and 7 days of storage, but no increment of catalase activity was observed after the irradiation. Furthermore, the protein profile was maintained throughout the irradiation and storage time, until the 21st day, with the presence of a protein fragmentation band of around 28 kDa on the 28th day. In conclusion, although gamma irradiation is the main agent for the prevention of TA-GVHD, a better understanding of the physical and biochemical properties of erythrocytes are necessary to better assess their viability, and to be able to issue more secure recommendations on the shelf life of blood bags, and the safe use of the irradiated red cells therein.

Challenges for red blood cell biomarker discovery through proteomics

Red blood cells are rather unique body cells, since they have lost all organelles when mature, which results in lack of potential to replace proteins that have lost their function. They maintain only a few pathways for obtaining energy and reducing power for the key functions they need to fulfill. This makes RBCs highly sensitive to any aberration. If so, these RBCs are quickly removed from circulation, but if the RBC levels reduce extremely fast, this results in hemolytic anemia. Several causes of HA exist, and proteome analysis is the most straightforward way to obtain deeper insight into RBC functioning under the stress of disease. This should result in discovery of biomarkers, typical for each source of anemia. In this review, several challenges to generate in-depth RBC proteomes are described, like to obtain pure RBCs, to overcome the wide dynamic range in protein expression, and to establish which of the identified/quantified proteins are active in RBCs. The final challenge is to acquire and validate suited biomarkers unique for the changes that occur for each of the clinical questions; in red blood cell aging (also important for transfusion medicine), for thalassemias or sickle cell disease. Biomarkers for other hemolytic anemias that are caused by dysfunction of RBC membrane proteins (the RBC membrane defects) or RBC cytosolic proteins (the enzymopathies) are sometimes even harder to discover, in particular for the patients with RBC rare diseases with unknown cause. This article is part of a Special Issue entitled: Biomarkers: A Proteomic Challenge.

Dynamic simulation and metabolome analysis of long-term erythrocyte storage in adenine-guanosine solution

Although intraerythrocytic ATP and 2,3-bisphophoglycerate (2,3-BPG) are known as direct indicators of the viability of preserved red blood cells and the efficiency of post-transfusion oxygen delivery, no current blood storage method in practical use has succeeded in maintaining both these metabolites at high levels for long periods. In this study, we constructed a mathematical kinetic model of comprehensive metabolism in red blood cells stored in a recently developed blood storage solution containing adenine and guanosine, which can maintain both ATP and 2,3-BPG. The predicted dynamics of metabolic intermediates in glycolysis, the pentose phosphate pathway, and purine salvage pathway were consistent with time-series metabolome data measured with capillary electrophoresis time-of-flight mass spectrometry over 5 weeks of storage. From the analysis of the simulation model, the metabolic roles and fates of the 2 major additives were illustrated: (1) adenine could enlarge the adenylate pool, which maintains constant ATP levels throughout the storage period and leads to production of metabolic waste, including hypoxanthine; (2) adenine also induces the consumption of ribose phosphates, which results in 2,3-BPG reduction, while (3) guanosine is converted to ribose phosphates, which can boost the activity of upper glycolysis and result in the efficient production of ATP and 2,3-BPG. This is the first attempt to clarify the underlying metabolic mechanism for maintaining levels of both ATP and 2,3-BPG in stored red blood cells with in silico analysis, as well as to analyze the trade-off and the interlock phenomena between the benefits and possible side effects of the storage-solution additives.

Cluster of erythrocyte band 3: a potential molecular target of exhaustive exercise-induced dysfunction of erythrocyte deformability

The aim of this study is to explore the effect of exhaustive exercise on erythrocyte band 3 (SLC4A1; EB3). The association between the alterations of EB3 and red blood cell (RBC) deformability induced by exercise-induced dysfunction has been investigated. Rats were divided among 2 groups: (i) control (C), and (ii) exercise exhausted (E). RBC deformability was investigated in the rats in the exhaustive exercise and control groups. Erythrocytes from the control and exercise-exhausted groups were evaluated for the expression of erythrocyte band 3 through immunoblotting and immunofluorescence studies. Exhaustive exercise led to significant increments in the levels of clustering of erythrocyte band 3 along with the conjugation of membrane proteins to form high-molecular-weight complexes (P < 0.05). Under shear stresses, RBC deformability was found to decline significantly in the exhaustive exercise groups compared with the control group. These data suggest that the RBC dysfunction observed during exercise-induced oxidative stress could be associated with alterations in the structure and function of erythrocyte band 3, which in turn leads to dysfunction in the rheological properties of RBCs. These results provide further insight into erythrocyte damage induced by exhaustive exercise.

Taxol®-induced phosphatidylserine exposure and microvesicle formation in red blood cells is mediated by its vehicle Cremophor® EL

Aim: The conventional clinical formulation of paclitaxel (PTX), Taxol®, consists of Cremophor® EL (CrEL) and ethanol. CrEL-formulated PTX is associated with acute hypersensitivity reactions, anemia and cardiovascular events. In this study, the authors investigated the effects of CrEL-PTX on red blood cells (RBCs) and compared these with the effects observed after exposure to the novel nanoparticle albumin-bound PTX, marketed as Abraxane®. Results: The authors demonstrate that CrEL is primarily responsible for RBC lysis and induction of phosphatidylserine exposure. Phosphatidylserine-exposing RBCs showed increased association with endothelial cells in culture. The authors also identified CrEL as being responsible for vesiculation of RBCs. This is the first time that excipients have been shown to be involved in microvesicle formation. Microvesicles were taken up by endothelial cells. Conclusion: These results offer new insights into the side effect profile of Taxol, which is likely to have implications for patients with erythrocyte disorders. Abraxane did not induce any of these effects on RBCs, indicating that the choice of excipients can have a pronounced influence on the efficacy and side effects of drug molecules.

Original submitted 16th April 2012; Revised submitted 24th August 2012; Published online 5 February 2013

Oxidative stress and caspase-mediated fragmentation of cytoplasmic domain of erythrocyte band 3 during blood storage

BACKGROUND

During blood bank storage, red blood cells (RBCs) undergo a number of biological and biochemical alterations collectively referred to as "storage lesions". These injuries include loss and oxidative cross-linking of band 3, the major integral protein of RBC membranes. Denaturation of hemoglobin (Hb) and damage to the amino-terminal of band 3 are recognised as the starting events for immunological recognition mechanisms and phagocytic removal of senescent or impaired RBCs from circulation. Consequently, studies focusing on the Hb-association and oxidative status of the cytoskeleton of stored RBCs intended for transfusion are of extreme interest. In this work, two storage-related fragments of band 3 were documented and biochemically characterised.

METHODS

Four RBC units were collected from normal volunteers and stored for 21 days under (i) standard blood bank conditions, (ii) anaerobic conditions, or (iii) in the presence of caspase 3-inhibitor. Degradation products of band 3 were followed by sodium dodecyl sulfatepolyacrylamide gel electrophoresis coupled with western blot and mass spectrometry analyses.

RESULTS

Two different degradation products of the cytoplasmic domain of the erythrocyte band 3 (CDB3) were detected in RBC membranes during storage in saline-adenine-glucosemannitol (SAGM) preservation medium. One of these fragments showed an apparent molecular weight of 34 kDa and was demonstrated to be the product of a free-radical attack on the protein main chain, whereas another fragment of 24 kDa was the result of a caspase 3-mediated cleavage.

DISCUSSION

Although to different extent, anaerobic conditions reduced the formation of both truncated products indicating an enhanced activity of the pro-apoptotic caspase 3 enzyme following oxidative stress. Interestingly, both CDB3 fragments were tightly associated to the erythrocyte membrane supporting the involvement of Cys-201 and/or Cys-317 in clustering different band 3 monomers.

Red blood cell microparticles and blood group antigens: an analysis by flow cytometry

BACKGROUND

The storage of blood induces the formation of erythrocytes-derived microparticles. Their pathogenic role in blood transfusion is not known so far, especially the risk to trigger alloantibody production in the recipient. This work aims to study the expression of clinically significant blood group antigens on the surface of red blood cells microparticles.

MATERIAL AND METHODS

Red blood cells contained in erythrocyte concentrates were stained with specific antibodies directed against blood group antigens and routinely used in immunohematology practice. After inducing erythrocytes vesiculation with calcium ionophore, the presence of blood group antigens was analysed by flow cytometry.

RESULTS

The expression of several blood group antigens from the RH, KEL, JK, FY, MNS, LE and LU systems was detected on erythrocyte microparticles. The presence of M (MNS1), N (MNS2) and s (MNS4) antigens could not be demonstrated by flow cytometry, despite that glycophorin A and B were identified on microparticles using anti-CD235a and anti-MNS3.

DISCUSSION

We conclude that blood group antigens are localized on erythrocytes-derived microparticles and probably keep their immunogenicity because of their capacity to bind specific antibody. Selective segregation process during vesiculation or their ability to elicit an immune response in vivo has to be tested by further studies.

Red blood cell populations and membrane levels of peroxiredoxin 2 as candidate biomarkers to reveal blood doping

BACKGROUND

Blood doping represents one main trend in doping strategies. Blood doping refers to the practice of boosting the number of red blood cells (RBCs) in the bloodstream in order to enhance athletic performance, by means of blood transfusions, administration of erythropoiesis-stimulating substances, blood substitutes, natural or artificial altitude facilities, and innovative gene therapies. While detection of recombinant EPO and homologous transfusion is already feasible through electrophoretic, mass spectrometry or flow cytometry-based approaches, no method is currently available to tackle doping strategies relying on autologous transfusions.

MATERIALS AND METHODS

We exploited an in vitro model of autologous transfusion through a 1:10 dilution of concentrated RBCs after 30 days of storage upon appropriate dilution in freshly withdrawn RBCs from the same donor. Western blot towards membrane Prdx2 and Percoll density gradients were exploited to assess their suitability as biomarkers of transfusion.

RESULTS

Membrane Prdx2 was visible in day 30 samples albeit not in day 0, while it was still visible in the 1:10 dilution of day 30 in day 0 RBCs. Cell gradients also highlighted changes in the profile of the RBC subpopulations upon dilution of stored RBCs in the fresh ones.

DISCUSSION

From this preliminary in vitro investigation it emerges that Prdx2 and RBC populations might be further tested as candidate biomarkers of blood doping through autologous transfusion, though it is yet to be assessed whether the kinetics in vivo of Prdx2 exposure in the membrane of transfused RBCs will endow a sufficient time-window to allow reliable anti-doping testing.

Red blood cell storage in SAGM and AS3: a comparison through the membrane two-dimensional electrophoresis proteome

BACKGROUND

SAGM is currently the standard additive solution used in Europe, while AS-3 is the third additive solution that has been licensed in the USA, and is also the one used in part of Canada. Although AS-3 is based on a saline-adenine-glucose solution, it also contains citrate and phosphate. Storage of red blood cell concentrates in CPD-SAGM is known to lead to the accumulation of a wide series of storage lesions, including membrane protein fragmentation and vesiculation, as we could previously determine through 2-dimensional gel electrophoresis.

MATERIALS AND METHODS

Through 2D-SDS-IEF-polyacrilamide gel electrophoresis we performed a time course analysis (day 0, 21 and 42 of storage) of red blood cell membranes from leukocyte-filtered concentrates either stored in CPD-SAGM or CP2D-AS-3.

RESULTS AND DISCUSSION

From the present study it emerges that the membrane protein profile of red blood cells stored in presence of AS-3 appears to be slightly different from (better than) previous reports on SAGM-stored counterparts. However, the increase of total membrane spot number due to the presence of fragments at day 21 and the significant decrease at day 42 are suggestive of a universal phenomenon which is not efficiently tackled by either of the two additive solutions investigated in the present study.

CONCLUSION

To further delve into the storage lesion issue for RBCs stored in AS-3, it would be interesting in the future to assay metabolic changes over storage progression as well.

Phospholipidomics reveals differences in glycerophosphoserine profiles of hypothermically stored red blood cells and microvesicles

During their normal in vivo life cycle erythrocytes (red blood cells, RBCs) undergo biochemical changes leading to membrane microvesiculation and shedding. RBC microvesiculation also occurs in vitro under conditions of blood bank storage, so microvesicles (MVs) accumulate in the storage (preservation) medium over storage time. Considerable effort has been put into gaining a mechanistic understanding of the RBC microvesiculation process, as this is crucial to better understand RBC biology in disease and in health. Additionally, MVs accumulated in stored RBCs have been implicated in transfusion adverse inflammatory reactions, with chloroform extractable compounds, thus lipophilic, known to trigger the effect. However, because thin layer chromatography resolution of RBC and MV lipids has always enabled one to conclude high compositional similarities, in depth analysis of MV lipids has not been extensively pursued. Here we present an orbitrap mass spectrometry (MS) approach to compare the phospholipid composition of RBCs and MVs from leukoreduced, hypothermically (2-6°C) stored RBC units. We used shotgun MS analysis and electrospray ionization (ESI) intra-source separation, and demonstrated high similarity of compositional profiles, except for glycerophosphoserines (PS). Contrasting abundances of PS 38:4 and PS 38:1 characterized MV and RBC profiles and suggested that storage-associated microvesiculation possibly involves shedding of specific membrane rafts. This finding indicates that phospholipidomics could likely contribute to a better understanding of the RBC microvesiculation process.

Effects of pre-storage leukoreduction on stored red blood cells signaling: a time-course evaluation from shape to proteome

The introduction of pre-storage leukoreduction in the preparation of standard RBCs intended for transfusion provided significant improvement in the quality of labile products and their post transfusion viability and effects, although the literature data are controversial. To elucidate the issue of the probable leukoreduction effects on RBCs storage lesion, we evaluated various storage quality measures in RBCs stored in either leukoreduced (L) or non-leukoreduced (N) units, with emphasis to senescence and oxidative stress associated modifications. Our data suggest that the residual leukocytes/platelets of the labile products represent a stressful storage factor, countering the structural and functional integrity of stored RBCs. Hemolysis, irreversible echinocytosis, microvesiculation, removal signaling, ROS/calcium accumulation, band 3-related senescence modifications, membrane proteome stress biomarkers as well as emergence of a senescence phenotype in young RBCs that is disproportionate to their age, are all encountered more or mostly in N-RBCs compared to the L-RBCs, either for a part or for the whole of the storage period. The partial, yet significant, alleviation of so many storage-related manifestations in the L-RBCs compared to the N-RBCs, is presented for the first time and provides a rational mechanistic interpretation of the improved storage quality and transfusions observed by the introduction of pre-storage leukoreduction. This article is part of a Special Issue entitled: Integrated omics.

Red blood cell subpopulations in freshly drawn blood: application of proteomics and metabolomics to a decades-long biological issue

BACKGROUND

It has long been known that red blood cells comprise various subpopulations, which can be separated through Percoll density gradients.

MATERIALS AND METHODS

In this study, we performed integrated flow cytometry, proteomic and metabolomic analyses on five distinct red blood cell subpopulations obtained by Percoll density gradient separation of freshly drawn leucocyte-depleted erythrocyte concentrates. The relation of density gradient fractions to cell age was confirmed through band 4.1a/4.1b assays.

RESULTS

We observed a decrease in size and increase in cell rugosity in older (denser) populations. Metabolomic analysis of fraction 5 (the oldest population) showed a decrease of glycolytic metabolism and of anti-oxidant defence-related mechanisms, resulting in decreased activation of the pentose phosphate pathway, less accumulation of NADPH and reduced glutathione and increased levels of oxidized glutathione. These observations strengthen conclusions about the role of oxidative stress in erythrocyte ageing in vivo, in analogy with results of recent in vitro studies. On the other hand, no substantial proteomic differences were observed among fractions. This result was partly explained by intrinsic technical limitations of the two-dimensional gel electrophoresis approach and the probable clearance from the bloodstream of erythrocytes with membrane protein alterations. Since this clearance effect is not present in vitro (in blood bank conditions), proteomic studies have shown substantial membrane lesions in ageing red blood cells in vitro.

CONCLUSION

This analysis shows that the three main red blood cell subpopulations, accounting for over 92% of the total RBC, are rather homogeneous soon after withdrawal. Major age-related alterations in vivo probably affect enzyme activities through post-translational mechanisms rather than through changes in the overall proteomic profile of RBC.