Glutathione loading prevents free radical injury in red blood cells after storage

The Role of Ergothioneine in Red Blood Cell Biology: A Review and Perspective

Oxidative stress can damage tissues and cells, and their resilience or susceptibility depends on the robustness of their antioxidant mechanisms. The latter include small molecules, proteins, and enzymes, which are linked together in metabolic pathways. Red blood cells are particularly susceptible to oxidative stress due to their large number of hemoglobin molecules, which can undergo auto-oxidation. This yields reactive oxygen species that participate in Fenton chemistry, ultimately damaging their membranes and cytosolic constituents. Fortunately, red blood cells contain robust antioxidant systems to enable them to circulate and perform their physiological functions, particularly delivering oxygen and removing carbon dioxide. Nonetheless, if red blood cells have insufficient antioxidant reserves (e.g., due to genetics, diet, disease, or toxin exposure), this can induce hemolysis in vivo or enhance susceptibility to a "storage lesion" in vitro, when blood donations are refrigerator-stored for transfusion purposes. Ergothioneine, a small molecule not synthesized by mammals, is obtained only through the diet. It is absorbed from the gut and enters cells using a highly specific transporter (i.e., SLC22A4). Certain cells and tissues, particularly red blood cells, contain high ergothioneine levels. Although no deficiency-related disease has been identified, evidence suggests ergothioneine may be a beneficial "nutraceutical." Given the requirements of red blood cells to resist oxidative stress and their high ergothioneine content, this review discusses ergothioneine's potential importance in protecting these cells and identifies knowledge gaps regarding its relevance in enhancing red blood cell circulatory, storage, and transfusion quality.

Attenuation of Oxidative Stress in Erythrocytes Stored with Vitamin C and l-Carnitine in Additive Solution-7

Background: Blood transfusion has advanced toward component therapy for specific requirements during trauma and surgery. Oxidative stress is induced in erythrocytes during storage. Hence, antioxidants as additives can be employed to counteract oxidative stress and enhance antioxidant defenses. Therefore, this study investigates the combinatorial effects of vitamin C and l-carnitine on erythrocytes during storage. Methodology: Erythrocyte samples were categorized into control and experimental groups-vitamin C (10 mM) and l-carnitine (10 mM) and stored under blood bank conditions (at 4°C) for 35 days. Hemoglobin (Hb), antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT] and glutathione peroxidase [GPX]), lipid peroxidation products (conjugate dienes and thiobarbituric acid reactive substances [TBARSs]), protein oxidation products, metabolic markers (glucose, lactate dehydrogenase), glutathione (GSH), superoxides, and hemolysis were assessed at weekly intervals. Results: SOD activity increased on day 7 in the controls, whereas it increased on days 7 and 14 in the experimental groups. CAT activity increased on day 35 in both the groups. GPX activity increased on day 7 in the controls. Hb levels decreased on days 14 and 35 in the controls and on day 35 in the experimental groups. Hemolysis increased from day 7 onward in both the groups. Protein oxidation products were maintained throughout the storage. GSH levels increased on day 21 in the controls and on days 14 and 21 in the experimental groups. Superoxides and conjugate dienes decreased from day 14 in both the groups. TBARSs decreased on day 7 in the experimental groups. Conclusion: Vitamin C and l-carnitine have synergistically enhanced the efficacy of stored erythrocytes in terms of Hb, antioxidant enzymes, and lipid peroxidation.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

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

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

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

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

Mitochondrial Oxidative Stress-A Causative Factor and Therapeutic Target in Many Diseases

The excessive formation of reactive oxygen species (ROS) and impairment of defensive antioxidant systems leads to a condition known as oxidative stress. The main source of free radicals responsible for oxidative stress is mitochondrial respiration. The deleterious effects of ROS on cellular biomolecules, including DNA, is a well-known phenomenon that can disrupt mitochondrial function and contribute to cellular damage and death, and the subsequent development of various disease processes. In this review, we summarize the most important findings that implicated mitochondrial oxidative stress in a wide variety of pathologies from Alzheimer disease (AD) to autoimmune type 1 diabetes. This review also discusses attempts to affect oxidative stress as a therapeutic avenue.

Do We Store Packed Red Blood Cells under "Quasi-Diabetic" Conditions?

Red blood cell (RBC) transfusion is one of the most common therapeutic procedures in modern medicine. Although frequently lifesaving, it often has deleterious side effects. RBC quality is one of the critical factors for transfusion efficacy and safety. The role of various factors in the cells’ ability to maintain their functionality during storage is widely discussed in professional literature. Thus, the extra- and intracellular factors inducing an accelerated RBC aging need to be identified and therapeutically modified. Despite the extensively studied in vivo effect of chronic hyperglycemia on RBC hemodynamic and metabolic properties, as well as on their lifespan, only limited attention has been directed at the high sugar concentration in RBCs storage media, a possible cause of damage to red blood cells. This mini-review aims to compare the biophysical and biochemical changes observed in the red blood cells during cold storage and in patients with non-insulin-dependent diabetes mellitus (NIDDM). Given the well-described corresponding RBC alterations in NIDDM and during cold storage, we may regard the stored (especially long-stored) RBCs as “quasi-diabetic”. Keeping in mind that these RBC modifications may be crucial for the initial steps of microvascular pathogenesis, suitable preventive care for the transfused patients should be considered. We hope that our hypothesis will stimulate targeted experimental research to establish a relationship between a high sugar concentration in a storage medium and a deterioration in cells’ functional properties during storage.

Quality assessment of red blood cell suspensions derived from pathogen-reduced whole blood

BACKGROUND

We used laboratory indicators to evaluate the quality of pathogen-reduced red blood cell suspension (RBCS) compared with gamma-irradiated RBCS.

MATERIALS AND METHODS

To determine biochemical and metabolic parameters of RBCS, we obtained 50 whole blood units from healthy volunteers and randomized them into 2 groups: 25 were pathogen-reduced, and then, RBCS prepared from them. RBCS from the other 25 was gamma-irradiated. Sampling was carried out on day zero before and after treatment and at 7, 14, 21 and 28 days. To determine lymphocyte inactivation, we collected another 35 whole blood units. Each was sampled to form 3 study groups: untreated, gamma-irradiated and pathogen-reduced. Daily sampling was carried out during 3 days of storage.

RESULTS

The quality of RBCS from both groups was largely the same, except for haemolysis and red blood cell fragility, which were more pronounced in the pathogen-reduced group. This finding limited the shelf life of pathogen-reduced RBCS to 14 days. Lymphocyte viability was significantly reduced after both treatments. Proliferation of lymphocytes after pathogen reduction was reduced to the detection limit, while low-level proliferation was observed in gamma-irradiated samples.

CONCLUSION

Pathogen-reduced red blood cells have acceptable quality and can be used for transfusion within 14 days. Results of inactivation of lymphocytes demonstrate that pathogen reduction technology, applied on WB, can serve as an alternative to irradiation.

The dielectric spectroscopy of human red blood cells during 37-day storage: β-dispersion parameterization

This study exploits dielectric spectroscopy to monitor the kinetics of red blood cells (RBC) storage lesions, focusing on those processes linked to cellular membrane interface known as β-dispersion. The dielectric response of RBC suspensions, exposed to blood-bank cold storage for 37 days, was studied using time-domain dielectric spectroscopy in the frequency range 500 kHz to 200 MHz. The measured dielectric processes are characterized by their dielectric strength (Δε) and their relaxation times (τ). Changes in the dielectric properties of the RBC suspensions, due to storage-related biophysical changes, were evaluated. For a quantitative characterization of RBC vitality, we characterized the shape of fresh and stored RBC and measured their deformability as expressed by their average elongation ratio, which was achieved under a shear stress of 3.0 Pa. During the second week of storage, an increment in the evolution of the relaxation times and in the dielectric permittivity strength of about 25% was observed. We propose that the characteristic increment of ATP, during the second and third weeks of storage, is responsible for the raise of the specific capacitance of cell membrane, which in turn explains the changes observed in the dielectric response when combined with the influence of the shape changes.

The Contribution of Storage Medium and Membranes in the Microwave Dielectric Response of Packed Red Blood Cells Suspension

During cold storage, packed red blood cells (PRBCs) undergo slow detrimental changes that are collectively termed storage lesion. The aging of the cells causes alterations in the composition of the storage-medium in the PRBC unit. In this paper, we present the comparison of the dielectric response of water in the primary (fresh) storage medium (citrate phosphate dextrose adenine solution, CPDA-1) versus the storage medium from three expired units of PRBCs. Dielectric response of the water molecules has been characterized by dielectric spectroscopy technique in the microwave frequency band (0.5–40 GHz). The dominant phenomenon is the significant increase of the dielectric strength and decrease the relaxation time τ for the samples of the stored medium in comparison with the fresh medium CPDA-1. Furthermore, we demonstrated that removing the ghosts from PRBC hemolysate did not cause the alteration of the dielectric spectrum of water. Thus, the contribution associated with water located near the cell membrane can be neglected in microwave dielectric measurements.

Impact of G6PD status on red cell storage and transfusion outcomes

There are inter-individual differences in the quality of refrigerator-stored red blood cells (RBCs). Possible sources of these variations include nutritional and genetic factors. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, the most common enzyme deficiency worldwide that affects the ability of RBCs to respond to oxidative stress, has been implicated as a genetic factor that affects the quality of stored RBCs. This review considers the literature concerning G6PD-deficient RBCs. It discusses RBC unit variables such as in vitro storage, 24-hour post-transfusion recovery (PTR), post-transfusion survival, and post-transfusion clinical outcomes.There are several differences in the in vitro storage characteristics between G6PD-deficient and G6PD-normal RBCs. Recent studies identified differences in the pathways related to glycolysis, purine metabolism, glutathione homeostasis, and fatty acid metabolism. In vitro experiments modelling the transfusion of G6PD-deficient RBCs, as well as autologous PTR studies in vivo, demonstrate increased haemolysis and decreased PTR, respectively, both indicators of a decrease in quality as compared to G6PD-normal RBCs. Finally, studies transfusing G6PD-deficient and G6PD-normal RBCs show that, in certain clinical settings, G6PD-deficient RBCs are associated with increased haemolysis.In summary, G6PD deficiency is associated with a decrease in the quality of RBCs after storage and its impact is often under-estimated. Understanding the underlying mechanisms by which G6PD deficiency affects RBC storage and transfusion outcomes may provide important clues to help optimise the future efficacy and safety of transfusions.

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

BACKGROUND

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

MATERIALS AND METHODS

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

RESULTS

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

DISCUSSION

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

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.

Donor Iron Deficiency Study (DIDS): protocol of a study to test whether iron deficiency in blood donors affects red blood cell recovery after transfusion

BACKGROUND

Despite fulfilling all requirements for blood donation, a large proportion of regular blood donors are iron deficient. Red blood cells (RBC) from iron-deficient donors may be particularly susceptible to damage induced by standard refrigerated storage. Herein, we present a study protocol for testing whether correcting iron deficiency in donors with iron-deficient erythropoiesis will improve the quality of their refrigerator-stored RBC.

MATERIALS AND METHODS

This is a randomised, controlled, double-blind clinical trial. Sixty healthy regular donors who meet donation standards, while exhibiting iron-deficient erythropoiesis by laboratory testing criteria, will donate a single standard RBC unit that will be leucoreduced and stored in a refrigerator under standard conditions for 40-42 days. A 51Cr-radiolabelled 24-hour RBC recovery study will be performed and then these donors will be randomised to receive, in a double-blinded fashion, either intravenous saline, as a control, or low-molecular weight iron dextran (1 g), to provide total iron repletion. Four to six months later, they will donate a second RBC unit, which will be similarly stored, and autologous 51Cr-labelled 24-hour post-transfusion RBC recovery will again be determined.

RESULTS

The primary endpoint will be the change in 24-hour post-transfusion recovery from the first to the second donation. The primary outcome will be the group mean difference in the primary endpoints between the group receiving intravenous saline and the group receiving intravenous iron dextran. Secondary outcomes will be quality of life, fatigue, and emotional health, assessed by surveys.

CONCLUSION

This study will provide definitive evidence as to whether donor iron deficiency affects the quality of the blood supply and will assess the severity of symptoms affecting iron-deficient blood donors.

Is It Possible to Reverse the Storage-Induced Lesion of Red Blood Cells?

Cold-storage of packed red blood cells (PRBCs) in the blood bank is reportedly associated with alteration in a wide range of RBC features, which change cell storage each on its own timescale. Thus, some of the changes take place at an early stage of storage (during the first 7 days), while others occur later. We still do not have a clear understanding what happens to the damaged PRBC following their transfusion. We know that some portion (from a few to 10%) of transfused cells with a high degree of damage are removed from the bloodstream immediately or in the first hour(s) after the transfusion. The remaining cells partially restore their functionality and remain in the recipient’s blood for a longer time. Thus, the ability of transfused cells to recover is a significant factor in PRBC transfusion effectiveness. In the present review, we discuss publications that examined RBC lesions induced by the cold storage, aiming to offer a better understanding of the time frame in which these lesions occur, with particular emphasis on the question of their reversibility. We argue that transfused RBCs are capable (in a matter of a few hours) of restoring their pre-storage levels of ATP and 2,3-DPG, with subsequent restoration of cell functionality, especially of those properties having a more pronounced ATP-dependence. The extent of reversal is inversely proportional to the extent of damage, and some of the changes cannot be reversed.

Validation of Candidate Serum Ovarian Cancer Biomarkers for Early Detection

Objective

We have previously analyzed protein profiles using Surface Enhanced Laser Desorption and Ionization Time-Of-Flight Mass Spectroscopy (SELDI-TOF-MS) [Kozak et al. 2003, Proc. Natl. Acad. Sci. U.S.A. 100:12343–8] and identified 3 differentially expressed serum proteins for the diagnosis of ovarian cancer (OC) [Kozak et al. 2005, Proteomics, 5:4589–96], namely, apolipoprotein A-I (apoA-I), transthyretin (TTR) and transferin (TF). The objective of the present study is to determine the efficacy of the three OC biomarkers for the detection of early stage (ES) OC, in direct comparison to CA125.

Methods

The levels of CA125, apoA-I, TTR and TF were measured in 392 serum samples [82 women with normal ovaries (N), 24 women with benign ovarian tumors (B), 85 women with ovarian tumors of low malignant potential (LMP), 126 women with early stage ovarian cancer (ESOC), and 75 women with late stage ovarian cancer (LSOC)], obtained through the GOG and Cooperative Human Tissue Network. Following statistical analysis, multivariate regression models were built to evaluate the utility of the three OC markers in early detection.

Results

Multiple logistic regression models (MLRM) utilizing all biomarker values (CA125, TTR, TF and apoA-I) from all histological subtypes (serous, mucinous, and endometrioid adenocarcinoma) distinguished normal samples from LMP with 91% sensitivity (specificity 92%), and normal samples from ESOC with a sensitivity of 89% (specificity 92%). MLRM, utilizing values of all four markers from only the mucinous histological subtype showed that collectively, CA125, TTR, TF and apoA-I, were able to distinguish normal samples from mucinous LMP with 90% sensitivity, and further distinguished normal samples from early stage mucinous ovarian cancer with a sensitivity of 95%. In contrast, in serum samples from patients with mucinous tumors, CA125 alone was able to distinguish normal samples from LMP and early stage ovarian cancer with a sensitivity of only 46% and 47%, respectively. Furthermore, collectively, apoA-I, TTR and TF (excluding CA-125) distinguished i) normal samples from samples representing all histopathologic subtypes of LMP, with a sensitivity of 73%, ii) normal samples from ESOC with a sensitivity of 84% and iii) normal samples from LSOC with a sensitivity of 97%. More strikingly, the sensitivity in distinguishing normal versus mucinous ESOC, utilizing apoA-I, TF and TTR (CA-125 excluded), was 95% (specificity 86%; AUC 95%).

Conclusions

These results suggest that the biomarker panel consisting of apoA-I, TTR and TF may significantly improve early detection of OC.

Iron-deficient erythropoiesis in blood donors and red blood cell recovery after transfusion: initial studies with a mouse model

BACKGROUND

Most frequent red cell (RBC) donors and many first-time donors are iron deficient, but meet haemoglobin standards. However, the effects of donation-induced iron deficiency on RBC storage quality are unknown. Thus, we used a mouse model to determine if donor iron deficiency reduced post-transfusion RBC recovery.

METHODS

Weanling mice received a control diet or an iron-deficient diet. A third group receiving the iron-deficient diet was also phlebotomised weekly. This provided 3 groups of mice with different iron status: (1) iron replete, (2) mild iron deficiency with iron-deficient erythropoiesis, and (3) iron-deficiency anaemia. At ten weeks of age, blood was collected, leucoreduced, and stored at 4 ºC. After 12 days of storage, 24-hour (h) post-transfusion RBC recovery was quantified in recipients by flow cytometry.

RESULTS

Before blood collection, mean haemoglobin concentrations in the iron-replete, iron-deficient, and iron-deficiency anaemia donor mice were 16.5±0.4, 11.5±0.4, and 7.0±1.4 [g/dL± 1 standard deviation (SD)], respectively (p<0.01 for all comparisons between groups). The 24-h post-transfusion RBC recoveries in recipients receiving transfusions from these three cohorts were 77.1±13.2, 66.5±10.9, and 46.7±15.9 (% ±1 SD), respectively (p<0.05 for all comparisons between groups).

DISCUSSION

In summary, donor iron deficiency significantly reduced 24-h post-transfusion RBC recovery in recipient mice. RBCs from mice with mild iron deficiency and iron-deficient erythropoiesis, with haemoglobin levels similar to those used for human autologous blood donation, had intermediate post-transfusion RBC recovery, as compared to iron-replete donors and those with iron-deficiency anaemia. This suggests that, in addition to the effects of iron deficiency on donor health, frequent blood donation, leading to iron-deficient erythropoiesis, may also have adverse effects for transfusion recipients.

Vitamin C and Trolox decrease oxidative stress and hemolysis in cold-stored human red blood cells

OBJECTIVES

To investigate the effects of sodium ascorbate (SA) (5-3125 μM) and a combination of SA and Trolox (25 and 125 μM) on oxidative changes generated in red blood cells (RBCs) followed by up to 20 days refrigerated storage.

METHODS

RBCs were isolated from CPD-preserved human blood. Percentage of hemolysis and extracellular activity of lactate dehydrogenase (LDH) were measured to assess the RBC membrane integrity. Lipid peroxidation (LPO), glutathione (GSH) and total antioxidant capacity (TAC) were quantified by thiobarbituric acid-reactive substances, Ellman's reagent and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) [Formula: see text]-based assay, respectively.

RESULTS

SA failed to reduce the storage-induced hemolysis and RBC membrane permeability. Addition of SA resulted in a concentration-independent LPO inhibition and increased TAC. A combination of SA/Trolox supplemented to the RBC medium significantly inhibited hemolysis, LDH leakage, LPO, GSH depletion and enhanced TAC.

DISCUSSION

The effects of vitamin C action are closely concentration-dependent and may be modulated by a variety of compounds (e.g. Hb degradation products) released from RBCs during the prolonged storage, changing its properties from anti- to pro-oxidative. The two different class antioxidants (SA/Trolox) could possibly cooperate to be good potential RBC storage additives ensuring both antiradical and membrane stabilizing protection.

The Relationship of Oxidation Sensitivity of Red Blood Cells and Carbonic Anhydrase Activity in Stored Human Blood: Effect of Certain Phenolic Compounds

It has been reported that many modifications occur with the increase of oxidative stress during storage in erythrocytes. In order to delay these negative changes, we evaluated whether the addition of substances likely to protect antioxidant capacity in stored blood would be useful. Therefore, we investigated the effects of resveratrol, tannic acid, and caffeic acid in lipid peroxidation and antioxidant capacity of erythrocytes in stored blood. Donated blood was taken into four CPD containing blood bags. One bag was used as the control, and the others were supplemented with caffeic acid (30 μg/mL), resveratrol (30 μg/mL), and tannic acid (15 μg/mL), respectively. Erythrocyte lipid peroxidation, sensitivity to oxidation, glutathione levels and carbonic anhydrase, glutathione peroxidase, and catalase activities were measured on days 0, 7, 14, 21, and 28. In the control group, erythrocyte malondialdehyde levels and sensitivity to oxidation were increased whereas glutathione, glutathione peroxidase, and catalase levels were decreased (p < 0.05). Resveratrol and caffeic acid prevented malondialdehyde accumulation and preserved glutathione, glutathione peroxidase, and catalase activities in erythrocytes. We demonstrated that resveratrol, caffeic acid, and tannic acid in stored blood could decrease the sensitivity to oxidation of erythrocytes in vitro but did not exhibit such effects on CA activity.

Small-Scale Perfusion Bioreactor of Red Blood Cells for Dynamic Studies of Cellular Pathways: Proof-of-Concept

To date, the development of bioreactors for the study of red blood cells (RBCs, daily transfused in the case of disease or hemorrhage) has focused on hematopoietic stem cells. Despite the fact that mature RBCs are enucleated and do not expand, they possess complex cellular and metabolic pathways, as well as post-translation modification signaling and gas-exchange regulation. In order to dynamically study the behavior of RBCs and their signaling pathways under various conditions, a small-scale perfusion bioreactor has been developed. The most advanced design developed here consists of a fluidized bed of 7.6 mL containing 3·10⁹ cells and perfused at 8.5 μL/min. Mimicking RBC storage conditions in transfusion medicine, as a proof-of-concept, we investigated the ex vivo aging of RBCs under both aerobic and anaerobic conditions. Hence, RBCs stored in saline-adenine-glucose-mannitol (SAGM) were injected in parallel into two bioreactors and perfused with a modified SAGM solution over 14 days at room temperature under air or argon. The formation of a fluidized bed enabled easy sampling of the extracellular medium over the storage period used for the quantitation of glucose consumption and lactate production. Hemolysis and microvesiculation increased during aging and were reduced under anaerobic (argon) conditions, which is consistent with previously reported findings. Glucose and lactate levels showed expected trends, i.e., decreased and increased during the 2-week period, respectively; whereas extracellular glucose consumption was higher under aerobic conditions. Metabolomics showed depletion of glycolsis and pentose phosphate pathway metabolites, and an accumulation of purine metabolite end-products. This novel approach, which takes advantage of a fluidized bed of cells in comparison to traditional closed bags or tubes, does not require agitation and limit shear stress, and constantly segragates extracellular medium from RBCs. It thus gives access to several difficult-to-obtain on- and off-line parameters in the extracellular medium. This dynamic bioreactor system does not only allow us to probe the behavior of RBCs under different storage conditions, but it also could be a powerful tool to study physiological or pathological RBCs exposed to various conditions and stimuli.

Therapeutic potential of manipulating suicidal erythrocyte death

INTRODUCTION

Eryptosis, the suicidal erythrocyte death, is characterized by erythrocyte shrinkage and phosphatidylserine translocation to the erythrocyte surface. Eryptosis is triggered by cell stress such as energy depletion and oxidative stress, by Ca(2+)-entry, ceramide, caspases, calpain and/or altered activity of several kinases. Phosphatidylserine-exposing erythrocytes adhere to the vascular wall and may thus impede microcirculation. Eryptotic cells are further engulfed by phagocytes and thus rapidly cleared from circulation.

AREAS COVERED

Stimulation of eryptosis contributes to anemia of several clinical conditions such as metabolic syndrome, diabetes, malignancy, hepatic failure, heart failure, uremia, hemolytic uremic syndrome, sepsis, fever, dehydration, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose-6-phosphate dehydrogenase deficiency and Wilson's disease. On the other hand, eryptosis with subsequent clearance of infected erythrocytes in malaria may counteract parasitemia.

EXPERT OPINION

In theory, anemia due to excessive eryptosis could be alleviated by treatment with small molecules inhibiting eryptosis. In malaria, stimulators of eryptosis may accelerate death of infected erythrocytes and thus favorably influence the clinical course of the disease. Many small molecules inhibit or stimulate eryptosis. Several stimulators favorably influence murine malaria. Further preclinical and subsequent clinical studies are required to elucidate the therapeutic potential of stimulators or inhibitors of eryptosis.

Triggers, inhibitors, mechanisms, and significance of eryptosis: the suicidal erythrocyte death

Suicidal erythrocyte death or eryptosis is characterized by erythrocyte shrinkage, cell membrane blebbing, and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Triggers of eryptosis include Ca(2+) entry, ceramide formation, stimulation of caspases, calpain activation, energy depletion, oxidative stress, and dysregulation of several kinases. Eryptosis is triggered by a wide variety of xenobiotics. It is inhibited by several xenobiotics and endogenous molecules including NO and erythropoietin. The susceptibility of erythrocytes to eryptosis increases with erythrocyte age. Phosphatidylserine exposing erythrocytes adhere to the vascular wall by binding to endothelial CXC-Motiv-Chemokin-16/Scavenger-receptor for phosphatidylserine and oxidized low density lipoprotein (CXCL16). Phosphatidylserine exposing erythrocytes are further engulfed by phagocytosing cells and are thus rapidly cleared from circulating blood. Eryptosis eliminates infected or defective erythrocytes thus counteracting parasitemia in malaria and preventing detrimental hemolysis of defective cells. Excessive eryptosis, however, may lead to anemia and may interfere with microcirculation. Enhanced eryptosis contributes to the pathophysiology of several clinical disorders including metabolic syndrome and diabetes, malignancy, cardiac and renal insufficiency, hemolytic uremic syndrome, sepsis, mycoplasma infection, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, and Wilson's disease. Facilitating or inhibiting eryptosis may be a therapeutic option in those disorders.

Influence of Pre-Storage Irradiation on the Oxidative Stress Markers, Membrane Integrity, Size and Shape of the Cold Stored Red Blood Cells

BACKGROUND

To investigate the extent of oxidative damage and changes in morphology of manually isolated red blood cells (RBCs) from whole blood, cold stored (up to 20 days) in polystyrene tubes and subjected to pre-storage irradiation (50 Gy) and to compare the properties of SAGM-preserved RBCs stored under experimental conditions (polystyrene tubes) with RBCs from standard blood bag storage.

METHODS

The percentage of hemolysis as well as the extracellular activity of LDH, thiobarbituric acid-reactive substances, reduced glutathione (GSH), and total antioxidant capacity (TAC) were measured. Changes in the topology of RBC membrane, shape, and size were evaluated by flow cytometry and judged against microscopy images.

RESULTS

Irradiation caused significant LDH release as well as increased hemolysis and lipid peroxidation, GSH depletion, and reduction of TAC. Prolonged storage of irradiated RBCs resulted in phosphatidylserine exposure on the cell surface. By day 20, approximately 60% of RBCs displayed non-discoid shape. We did not notice significant differences in percentage of altered cells and cell volume between RBCs exposed to irradiation and those not exposed.

CONCLUSION

Irradiation of RBC transfusion units with a dose of 50 Gy should be avoided. For research purposes such as studying the role of antioxidants, storage of small volumes of RBCs derived from the same donor would be more useful, cheaper, and blood-saving.

Heritability of glutathione and related metabolites in stored red blood cells

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

Oxidative stress and suicidal erythrocyte death

SIGNIFICANCE

Eryptosis, the suicidal erythrocyte death, is characterized by cell shrinkage, membrane blebbing, and phosphatidylserine translocation to the outer membrane leaflet. Phosphatidylserine at the erythrocyte surface binds endothelial CXCL16/SR-PSOX (CXC-Motiv-Chemokin-16/Scavenger-receptor-for-phosphatidylserine-and-oxidized-low-density-lipoprotein) and fosters engulfment of affected erythrocytes by phagocytosing cells. Eryptosis serves to eliminate infected or defective erythrocytes, but excessive eryptosis may lead to anemia and may interfere with microcirculation. Clinical conditions with excessive eryptosis include diabetes, chronic renal failure, hemolytic uremic syndrome, sepsis, malaria, iron deficiency, sickle cell anemia, thalassemia, glucose 6-phosphate dehydrogenase deficiency, glutamate cysteine ligase modulator deficiency, and Wilson's disease.

RECENT ADVANCES

Eryptosis is triggered by a wide variety of xenobiotics and other injuries such as oxidative stress. Signaling of eryptosis includes prostaglandin E₂ formation with subsequent activation of Ca(2+)-permeable cation channels, Ca(2+) entry, activation of Ca(2+)-sensitive K(+) channels, and cell membrane scrambling, as well as phospholipase A2 stimulation with release of platelet-activating factor, sphingomyelinase activation, and ceramide formation. Eryptosis may involve stimulation of caspases and calpain with subsequent degradation of the cytoskeleton. It is regulated by AMP-activated kinase, cGMP-dependent protein kinase, Janus-activated kinase 3, casein kinase 1α, p38 kinase, and p21-activated kinase 2. It is inhibited by erythropoietin, antioxidants, and further small molecules.

CRITICAL ISSUES

It remains uncertain for most disorders whether eryptosis is rather beneficial because it precedes and thus prevents hemolysis or whether it is harmful because of induction of anemia and impairment of microcirculation.

FUTURE DIRECTIONS

This will address the significance of eryptosis, further mechanisms underlying eryptosis, and additional pharmacological tools fostering or inhibiting eryptosis.

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.

Storage-induced damage to red blood cell mechanical properties can be only partially reversed by rejuvenation

BACKGROUND

The storage of red blood cells (RBC) is associated with impairment of their properties that can induce a circulatory risk to recipients. In a preceding study (2009), we reported that post-storage rejuvenation (RJ) of stored RBC (St-RBC) efficiently reduced the storage-induced RBC/endothelial cell interaction, while only partially reversing the level of intracellular Ca(2+), reactive oxygen species, and surface phosphatidylserine. In the present study, we examined the RJ effectiveness in repairing St-RBC mechanical properties.

METHODS

RBC, stored in CPDA-1 without pre-storage leukoreduction, were subjected to post-storage RJ, and the deformability, osmotic fragility (OF), and mechanical fragility (MF) of the rejuvenated St-RBC (St-RBCRj) were compared to those of untreated St-RBC and of freshly-collected RBC (F-RBC).

RESULTS

5-week storage considerably increased OF and MF, and reduced the deformability of St-RBC. All alterations were only partially (40-70%) reversed by RJ, depending on the extent of the damage: the greater the damage, the lesser the relative effect of RJ.

CONCLUSION

The findings of the present and preceding studies suggest that different St-RBC properties are differentially reversed by RJ, implying that some of the changes occur during storage and are irreversible.

Red blood cell in vitro quality and function is maintained after S-303 pathogen inactivation treatment

BACKGROUND

Over the past decade there has been a growth in the development of pathogen reduction technologies to protect the blood supply from emerging pathogens. This development has proven to be difficult for red blood cells (RBCs). However the S-303 system has been shown to effectively inactivate a broad spectrum of pathogens, while maintaining RBC quality.

STUDY DESIGN AND METHODS

A paired three-arm study was performed to compare the in vitro quality of S-303-treated RBCs with RBCs stored at room temperature (RT) for the duration of the treatment (18-20 hr) and control RBCs stored at 2 to 6°C. Products were sampled weekly over 42 days of storage (n = 10) and tested using an array of in vitro assays to measure quality, metabolism, and functional variables.

RESULTS

During S-303 treatment there was a slight loss of RBCs and hemoglobin (Hb < 5 g). Hemolysis, glucose consumption, and potassium release were similar in all groups during the 42 days of storage. S-303-treated RBCs had a significantly lower lactate concentration and pH compared to the paired controls. The S-303-treated RBCs had significantly higher adenosine triphosphate than the RT and control RBCs. There was a significant loss of 2,3-diphosphoglycerate in the S-303-treated products, which was also observed in the RT RBCs. Flow cytometry analysis demonstrated similar RBC size, morphology, expression of CD47, and glycophorin A in all groups.

CONCLUSION

RBCs treated with S-303 for pathogen reduction had similar in vitro properties to the paired controls and were within transfusion guidelines.

Strain-specific red blood cell storage, metabolism, and eicosanoid generation in a mouse model

BACKGROUND

Red blood cell (RBC) transfusion is a lifesaving therapy, the logistic implementation of which requires RBC storage. However, stored RBCs exhibit substantial donor variability in multiple characteristics, including hemolysis in vitro and RBC recovery in vivo. The basis of donor variability is poorly understood.

STUDY DESIGN AND METHODS

We applied a murine model of RBC storage and transfusion to test the hypothesis that genetically distinct inbred strains of mice would demonstrate strain-specific differences in RBC storage. In vivo recoveries were determined by monitoring transfused RBCs over 24 hours. Timed aliquots of stored RBCs were subjected to tandem chromatography/mass spectrometry analysis to elucidate metabolic changes in the RBCs during storage.

RESULTS

Using independent inbred mouse strains as donors, we found substantial strain-specific differences in posttransfusion RBC recovery in vivo after standardized refrigerated storage in vitro. Poor posttransfusion RBC recovery correlated with reproducible metabolic variations in the stored RBC units, including increased lipid peroxidation, decreased levels of multiple natural antioxidants, and accumulation of cytidine. Strain-dependent differences were also observed in eicosanoid generation (i.e., prostaglandins and leukotrienes).

CONCLUSION

These findings provide the first evidence of strain-specific metabolomic differences after refrigerated storage of murine RBCs. They also provide the first definitive biochemical evidence for strain-specific variation of eicosanoid generation during RBC storage. The molecules described that correlate with RBC storage quality, and their associated biochemical pathways, suggest multiple causal hypotheses that can be tested regarding predicting the quality of RBC units before transfusion and developing methods of improved RBC storage.

Innate immune activation after transfusion of stored red blood cells

The transfusion of red blood cells (RBCs), although necessary for treatment of anemia and blood loss, has also been linked to increased morbidity and mortality. RBCs stored for longer durations and transfused in larger volumes are often cited as contributory to adverse outcomes. The potential mechanisms underlying deleterious effects of RBC transfusion are just beginning to be elucidated. In this narrative review, we explore the hypothesis that prolonged RBC storage results in elaboration of substances which may function as danger associated molecular pattern molecules that activate the innate immune system with consequences unfavorable to healthy homeostasis. The nature of these chemical mediators and the biological responses to them offers insight into the mechanisms of these pathological responses. Three major areas of activation of the innate immune apparatus by stored RBCs have been tentatively identified: RBC hemolysis, recipient neutrophil priming, and reactive oxygen species production. The possible mechanisms by which each might perturb the innate immune response are reviewed in a search for potential novel pathways through which transfusion can lead to an altered inflammatory response.

Ascorbic acid improves membrane fragility and decreases haemolysis during red blood cell storage

BACKGROUND

Changes that occur to red blood cells (RBCs) during routine blood bank storage include decreased deformability, increased haemolysis and oxidative damage. Oxidative injury to the RBC membrane and haemoglobin can affect changes in shape and deformability. Ascorbic acid (AA) is an antioxidant that maintains haemoglobin in a reduced state and minimises RBC oxidative injury. We hypothesised that AA would improve membrane fragility and decrease haemolysis during storage.

METHODS

Whole blood derived, AS-5 preserved, pre-storage leucoreduced RBC units were exposed to either AA or saline control solutions. Several rheological and biochemical parameters were measured serially during storage, including RBC membrane mechanical fragility, percent haemolysis and methaemoglobin levels.

RESULTS

AA exposure significantly reduced mechanical fragility and haemolysis over the entire storage period. The highest two concentrations of AA affected the greatest reductions in mechanical fragility and percent haemolysis. Addition of AA to the RBCs did not significantly alter their biochemical parameters compared to control RBCs incubated with saline.

CONCLUSION

AA reduced RBC membrane fragility and decreased haemolysis during storage without adversely affecting other RBC biochemical parameters. The clinical significance of these findings needs to be determined.

The susceptibility of erythrocytes to oxidation during storage of blood: effects of melatonin and propofol

OBJECTIVES

We investigated the effects of melatonin and propofol in lipid peroxidation and antioxidant capacity of erythrocytes in stored bloods.

DESIGN AND METHODS

Donated blood was taken into three citrate-phosphate-dextrose containing blood bags. One bag was used as control, the others were added either melatonin or propofol. Erythrocyte lipid peroxidation and antioxidant capacity and their sensitivity to in vitro oxidation were measured on days 0, 7, 14, 21 and 28.

RESULTS

In control group, erythrocyte malondialdehyde levels and sensitivity to in vitro oxidation were increased whereas glutathione, glutathione peroxidase and superoxide dismutase levels were decreased. Melatonin prevented malondialdehyde accumulation and preserved glutathione, glutathione peroxidase and superoxide dismutase levels. Propofol preserved glutathione and glutathione peroxidase levels but did not affect catalase and superoxide dismutase activities.

CONCLUSIONS

We showed that melatonin in stored blood could prevent lipid peroxidation and increase the resistance of erythrocytes to in vitro oxidation while propofol did not show such effects.

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

BACKGROUND

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

STUDY DESIGN AND METHODS

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

RESULTS

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

CONCLUSION

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

Oxidative stress-dependent oligomeric status of erythrocyte peroxiredoxin II (PrxII) during storage under standard blood banking conditions

Although biochemical properties of 2-Cys peroxiredoxins have been extensively studied in various cell lines and organisms, redox-induced structural transitions of peroxiredoxin II (PrxII) in human erythrocytes certainly warrant further investigation. In this work, cytosol and membrane ghosts of both fresh erythrocytes (cells obtained just after blood collection) and 28-day stored erythrocytes were analyzed by proteomics tools. We demonstrated that in fresh red blood cells PrxII exhibits four different oligomeric states in cytosol, whereas no PrxII complexes are in the membrane. The highest molecular weight PrxII protein complex (440 kDa) was proven to derive from the association between tetrameric catalase (CAT, 232 kDa) and decameric PrxII, whereas oligomers at 140, 100 and 67 kDa resulted to be homo-polymeric complexes composed of variable copies of PrxII monomeric subunits. Interestingly, the 440 kDa complex contained both reduced and oxidized (disulphide-linked dimers) PrxII decamers. Upon oxidative stress (28-day storage), the PrxII oligomers at 100 kDa in the cytosol disappeared and the CAT-PrxII hetero-oligomeric complex at 440 kDa is converted to a higher molecular weight structure (480 kDa) due to the presence therein of cross-linked species of PrxII and hemoglobin. More interestingly, oxidized red cell membranes contained the CAT-PrxII complex detected in 0-day cytosol as a consequence of protein recruitments induced by oxidative stress, however it showed a greater percentage of PrxII dimers. Finally, since the adoption of distinct PrxII structures is known to be closely related to different functions, peroxidase activity assays were performed demonstrating a positive reaction for oligomers at 440 kDa (both in cytosol and membrane compartment) and at 140 kDa. Our results contribute to clarify structural and functional switching of peroxiredoxin II in erythrocytes, thus possibly opening new scenarios in the biological roles played by this protein in defense mechanisms against oxidative stress, especially with the reference to red cell storage lesions.

Advanced glycation end products on stored red blood cells increase endothelial reactive oxygen species generation through interaction with receptor for advanced glycation end products

BACKGROUND

Recent evidence suggests that storage-induced alterations of the red blood cell (RBC) are associated with adverse consequences in susceptible hosts. As RBCs have been shown to form advanced glycation end products (AGEs) after increased oxidative stress and under pathologic conditions, we examined whether stored RBCs undergo modification with the specific AGE N-(carboxymethyl)lysine (N(ε) -CML) during standard blood banking conditions.

STUDY DESIGN AND METHODS

Purified, fresh RBCs from volunteers were compared to stored RBCs (35-42 days old) obtained from the blood bank. N(ε) -CML formation was quantified using a competitive enzyme-linked immunosorbent assay. The receptor for advanced glycation end products (RAGE) was detected in human pulmonary microvascular endothelial cells (HMVEC-L) by real-time polymerase chain reaction, Western blotting, and flow cytometry. Intracellular reactive oxygen species (ROS) generation was measured by the use of 5-(and 6-)chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester-based assays.

RESULTS

Stored RBCs showed increased surface N(ε) -CML formation when compared with fresh RBCs. HMVEC-L showed detectable surface RAGE expression constitutively. When compared to fresh RBCs, stored RBCs triggered increased intracellular ROS generation in both human umbilical vein endothelial cells and HMVEC-L. RBC-induced endothelial ROS generation was attenuated in the presence of soluble RAGE or RAGE blocking antibody.

CONCLUSIONS

The formation of the AGE N(ε) -CML on the surface of stored RBCs is one functional consequence of the storage lesion. AGE-RAGE interactions may be one mechanism by which transfused RBCs cause endothelial cell damage.

Red cell changes during storage

Red blood cells can be stored in liquid suspension in approved additive solutions for periods up to 6 weeks with 0.4% hemolysis, 84% 24-h in vivo recovery, and normal subsequent survival of the cells that persist in the circulation for at least 24h. However, while they are stored, the red cells undergo changes including the loss of adenosine triphosphate, diphosphoglycerate, and potassium, oxidative injury to proteins, lipids, and carbohydrates, loss of shape and membrane, increased adhesiveness, decreased flexibility, reduced capillary flow, and decreased oxygen delivery. Deaths have been reported related to the high potassium and lysophospholipids, but are rare.

Biopreservation of red blood cells--the struggle with hemoglobin oxidation

One of the least recognized causes of cellular damage during ex vivo preservation of red blood cells is oxidative injury to the hemoglobin. The latter has been associated with hemolysis through the release of toxic substances and oxidation of vital cell components. This review delineates some of the major pathways that link hemoglobin oxidation and cellular damage, and summarizes the incidence of red blood cell oxidative injury during hypothermic storage, cryopreservation and desiccation stress. Red blood cell hypothermic storage, despite its success, is not exempt from oxidative injury. Growing evidence portrays a time-dependant oxidative assault including formation of reactive oxygen species, attachment of denatured hemoglobin to membrane phospholipids and the release of hemoglobin-containing membrane microvesicles throughout storage. Similar symptoms have been observed in attempts to stabilize red blood cells in the dried state, in which methemoglobin levels of reconstituted red blood cells reached 50%. Factors affecting the rate of hemoglobin oxidation during red blood cell ex vivo storage include compromised antioxidant activity, high concentrations of glucose in the storage media and the presence of molecular oxygen. Hemoglobin oxidation largely dictates our ability to effectively preserve red blood cells. Understanding its origins along with investigating methods to minimize it can significantly improve the quality of our future blood products.

Red cell storage

Blood component storage allows the donor and recipient to be separated in time and space. This separation converts transfusion from a desperate clinical act into a planned, orderly healthcare logistic activity with concomitant increases in both blood product availability and safety. However, storage has the potential to reduce the efficacy of transfused blood components by reducing their flow, functional capacity, and survival. Storage time also allows the accumulation of leaked potassium from red cells and the growth of contaminating bacteria. Many different aspects of the red cell storage lesion have been described, including changes in metabolism, shape, and rheology changes, loss of membrane carbohydrates, lipids and proteins, and alterations in secretion, oxygen delivery, and adhesion. What has been harder to show is that these known changes have significant clinical effects. Therefore, regulatory decisions about product storage have been conservative, and largely based on historic patterns of use. The increasing power of proteomics and metabolomics offers the potential of deeper understanding of blood function and storage and of better clinical products in the future.

Zinc-activated C-peptide resistance to the type 2 diabetic erythrocyte is associated with hyperglycemia-induced phosphatidylserine externalization and reversed by metformin

Insulin resistance can broadly be defined as the diminished ability of cells to respond to the action of insulin in transporting glucose from the bloodstream into cells and tissues. Here, we report that erythrocytes (ERYs) obtained from type 2 diabetic rats display an apparent resistance to Zn(2+)-activated C-peptide. Thus, the aims of this study were to demonstrate that Zn(2+)-activated C-peptide exerts potentially beneficial effects on healthy ERYs and that these same effects on type 2 diabetic ERYs are enhanced in the presence of metformin. Incubation of ERYs (obtained from type 2 diabetic BBZDR/Wor-rats) with Zn(2+)-activated C-peptide followed by chemiluminescence measurements of ATP resulted in a 31.2 +/- 4.0% increase in ATP release from these ERYs compared to a 78.4 +/- 4.9% increase from control ERYs. Glucose accumulation in diabetic ERYs, measured by scintillation counting of (14)C-labeled glucose, increased by 35.8 +/- 1.3% in the presence of the Zn(2+)-activated C-peptide, a value significantly lower than results obtained from control ERYs (64.3 +/- 5.1%). When Zn(2+)-activated C-peptide was exogenously added to diabetic ERYs, immunoassays revealed a 32.5 +/- 8.2% increase in C-peptide absorbance compared to a 64.4 +/- 10.3% increase in control ERYs. Phosphatidylserine (PS) externalization and metformin sensitization of Zn(2+)-activated C-peptide were examined spectrofluorometrically by measuring the binding of FITC-labeled annexin to PS. The incubation of diabetic ERYs with metformin prior to the addition of Zn(2+)-activated C-peptide resulted in values that were statistically equivalent to those of controls. Summarily, data obtained here demonstrate an apparent resistance to Zn(2+)-activated C-peptide by the ERY that is corrected by metformin.

Chromatographic and mass spectrometric analysis of glutathione in biological samples

Biological thiol compounds are classified into high-molecular-mass protein thiols and low-molecular-mass free thiols. Endogenous low-molecular-mass thiol compounds, namely, reduced glutathione (GSH) and its corresponding disulfide, glutathione disulfide (GSSG), are very important molecules that participate in a variety of physiological and pathological processes. GSH plays an essential role in protecting cells from oxidative and nitrosative stress and GSSG can be converted into the reduced form by action of glutathione reductase. Measurement of GSH and GSSG is a useful indicator of oxidative stress and disease risk. Many publications have reported successful determination of GSH and GSSG in biological samples. In this article, we review newly developed techniques, such as liquid chromatography coupled with mass spectrometry and tandem mass spectrometry, for identifying GSH bound to proteins, or for localizing GSH in bound or free forms at specific sites in organs and in cellular locations.