Erythrocyte ageingin vivoandin vitro: structural aspects and implications for transfusion

Red blood cell transfusion in infants and children - Current perspectives

Children routinely receive packed red blood transfusion when they are admitted in the intensive care unit or undergoing cardiac surgeries. These guidelines aim to summarize literature and provide transfusion triggers exclusively in infants and children.

Vitamin E Analogue Protects Red Blood Cells against Storage-Induced Oxidative Damage

Background

To investigate i) the effects of Trolox® or mannitol, which represent two different classes of antioxidants, on oxidative changes generated in manually isolated red blood cells (RBCs) from citrate-phosphate-dextrose (CPD) preserved whole blood, followed by up to 20 days refrigerated storage, and ii) whether Trolox supplemented to the blood bank-manufactured saline-adenine-glucose-mannitol (SAGM) preserved RBC units would offer better storage conditions compared with SAGM alone.

Methods

The percentage of hemolysis and extracellular activity of lactate dehydrogenase (LDH) was measured to assess RBC membrane integrity. Lipid peroxidation, reduced glutathione (GSH) levels and total antioxidant capacity (TAC) were quantified by thiobarbituric acid-reactive substances (TBARS), Ellman's reagent and 2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS^.+) based assay, respectively.

Results

Trolox was little more effective than mannitol in protecting against progressive RBC hemolysis. Trolox (0.125-3.125 mmol/l) inhibited storage-induced leakage of LDH, lipid peroxidation, and to a lesser extent GSH depletion. Mannitol at these concentrations neither inhibited TBARS formation nor prevented GSH depletion. RBC units stored in SAGM-Trolox had significantly lower hemolysis, LDH leakage, and lipid peroxidation level compared to RBCs stored in SAGM.

Conclusion

There is evidence of the beneficial effects of supplementing RBC-additive solutions with membrane-interacting antioxidants such as vitamin E analogues.

Change of plasmalogen content of red blood cells in myocardial hypoxia and acidosis

BACKGROUND

The contribution of hypoxic conditions to the chemical composition of membranes is not completely established. Plasmalogens, containing an alkenyl group with aldehydogenic ether linkage, are significant components of membrane lipids and their level can change in oxygen deficiency.

METHODS

Analysis of plasmalogens in red blood cells was performed in patients (n = 17) with coronary heart disease, stable angina (functional class II-III) and coronary atherosclerosis. The control group consisted of 17 healthy volunteers. In addition, isolated blood samples of seven healthy volunteers were analysed before and after 180 min incubation at 37 °C. Fatty acid ethyl esters and diethyl acetals of fatty aldehydes, obtained during sample preparation from red blood cells, were analysed by capillary gas-liquid chromatography. Quantitative assessment of the change of the plasmalogen levels was evaluated as change of the share of fatty aldehyde diethyl acetals in the total sum of fatty aldehyde diethyl acetals and fatty acid ethyl esters.

RESULTS

In comparison with the healthy volunteers, an increase in plasmalogen content of red blood cells and a reduction of the pH of the blood plasma in the group of patients with coronary heart disease were detected. In experimental hypoxia, there was an increase in the plasmalogen content of the red blood cells and a plasma pH decrease in all samples subjected to the incubation.

CONCLUSIONS

The results indicate changes in the physicochemical properties of the cell membrane in hypoxia. One of the most likely reasons of the increase of plasmalogen content in the membranes may be a more significant increase in activity of calcium-dependent phospholipases in comparison with the activity of calcium-independent plasmalogen phospholipases.

Physiologic Impact of Circulating RBC Microparticles upon Blood-Vascular Interactions

Here, we review current data elucidating the role of red blood cell derived microparticles (RMPs) in normal vascular physiology and disease progression. Microparticles (MPs) are submicron-size, membrane-encapsulated vesicles derived from various parent cell types. MPs are produced in response to numerous stimuli that promote a sequence of cytoskeletal and membrane phospholipid changes and resulting MP genesis. MPs were originally considered as potential biomarkers for multiple disease processes and more recently are recognized to have pleiotropic biological effects, most notably in: promotion of coagulation, production and handling of reactive oxygen species, immune modulation, angiogenesis, and in initiating apoptosis. RMPs, specifically, form normally during RBC maturation in response to injury during circulation, and are copiously produced during processing and storage for transfusion. Notably, several factors during RBC storage are known to trigger RMP production, including: increased intracellular calcium, increased potassium leakage, and energy failure with ATP depletion. Of note, RMP composition differs markedly from that of intact RBCs and the nature/composition of RMP components are affected by the specific circumstances of RMP genesis. Described RMP bioactivities include: promotion of coagulation, immune modulation, and promotion of endothelial adhesion as well as influence upon vasoregulation via influence upon nitric oxide (NO) bioavailability. Of particular relevance, RMPs scavenge NO more avidly than do intact RBCs; this physiology has been proposed to contribute to the impaired oxygen delivery homeostasis that may be observed following transfusion. In summary, RMPs are submicron particles released from RBCs, with demonstrated vasoactive properties that appear to disturb oxygen delivery homeostasis. The clinical impact of RMPs in normal and patho-physiology and in transfusion recipients is an area of continued investigation.

Perioperative red blood cell transfusion in orofacial surgery

In the field of orofacial surgery, a red blood cell transfusion (RBCT) is occasionally required during double jaw and oral cancer surgery. However, the question remains whether the effect of RBCT during the perioperative period is beneficial or harmful. The answer to this question remains challenging. In the field of orofacial surgery, transfusion is performed for the purpose of oxygen transfer to hypoxic tissues and plasma volume expansion when there is bleeding. However, there are various risks, such as infectious complications (viral and bacterial), transfusion-related acute lung injury, ABO and non-ABO associated hemolytic transfusion reactions, febrile non-hemolytic transfusion reactions, transfusion associated graft-versus-host disease, transfusion associated circulatory overload, and hypersensitivity transfusion reaction including anaphylaxis and transfusion-related immune-modulation. Many studies and guidelines have suggested RBCT is considered when hemoglobin levels recorded are 7 g/dL for general patients and 8-9 g/dL for patients with cardiovascular disease or hemodynamically unstable patients. However, RBCT is occasionally an essential treatment during surgeries and it is often required in emergency cases. We need to comprehensively consider postoperative bleeding, different clinical situations, the level of intra- and postoperative patient monitoring, and various problems that may arise from a transfusion, in the perspective of patient safety. Since orofacial surgery has an especially high risk of bleeding due to the complex structures involved and the extensive vascular distribution, measures to prevent bleeding should be taken and the conditions for a transfusion should be optimized and appropriate in order to promote patient safety.

Maturation of phagosomes containing different erythrophagocytic particles in primary macrophages

Erythrophagocytosis is a physiological process that aims to remove damaged red blood cells from the circulation in order to avoid hemolysis and uncontrolled liberation of iron. Many efforts have been made to understand heme trafficking inside macrophages, but little is known about the maturation of phagosomes containing different types of erythrophagocytic particles with different signals at their surfaces. Therefore, we performed a comparative study on the maturation of phagosomes containing three different models of red blood cells (RBC): aged/senescent, complement-opsonized, and IgG-opsonized. We also used two types of professional phagocytes: bone marrow-derived and peritoneal macrophages. By comparing markers from different stages of phagosomal maturation, we found that phagosomes carrying aged RBC reach lysosomes with a delay compared to those containing IgG- or complement-opsonized RBC, in both types of macrophages. These findings contribute to understanding the importance of the different signals at the RBC surface in phagolysosome biogenesis, as well as in the dynamics of RBC removal.

Macrophages and Iron Metabolism

Macrophages exert multiple important roles in iron metabolism. As scavengers, splenic and hepatic macrophages phagocytize and degrade senescent and damaged erythrocytes to recycle iron, predominantly for the production of hemoglobin in new erythrocytes. Splenic red pulp macrophages are specialized for iron recycling, with increased expression of proteins for the uptake of hemoglobin, breakdown of heme, and export of iron. Iron release from macrophages is closely regulated by the interaction of hepcidin, a peptide hormone produced by hepatocytes, with the macrophage iron exporter ferroportin. As regulators and effectors of antimicrobial host defense, macrophages employ multiple mechanisms to contain microbial infections by depriving microbes of iron. Macrophages also have an important trophic role in the bone marrow, supporting efficient erythropoiesis.

Contribution of plasma membrane lipid domains to red blood cell (re)shaping

Although lipid domains have been evidenced in several living cell plasma membranes, their roles remain largely unclear. We here investigated whether they could contribute to function-associated cell (re)shaping. To address this question, we used erythrocytes as cellular model since they (i) exhibit a specific biconcave shape, allowing for reversible deformation in blood circulation, which is lost by membrane vesiculation upon aging; and (ii) display at their outer plasma membrane leaflet two types of submicrometric domains differently enriched in cholesterol and sphingomyelin. We here reveal the specific association of cholesterol- and sphingomyelin-enriched domains with distinct curvature areas of the erythrocyte biconcave membrane. Upon erythrocyte deformation, cholesterol-enriched domains gathered in high curvature areas. In contrast, sphingomyelin-enriched domains increased in abundance upon calcium efflux during shape restoration. Upon erythrocyte storage at 4 °C (to mimick aging), lipid domains appeared as specific vesiculation sites. Altogether, our data indicate that lipid domains could contribute to erythrocyte function-associated (re)shaping.

Association between body size and selected hematological parameters in men and women aged 45 and above from a hospitalized population of older adults: an insight from the Polish Longitudinal Study of Aging (1960–2000)

In elderly people, anemia occurs with increasing frequency with each advancing decade and can be a harbinger of very serious health conditions, including gastrointestinal bleeding, gastric and duodenal ulcers, and cancer. Therefore, age-dependant changes in hematological parameters deserve special attention. Nonetheless, very few longitudinal studies of aging have focused on possible associations between basic anthropometric characteristics and hematological parameters in older people. Here, we present some evidence that body size can be associated with red blood cell count as well as some other selected hematological parameters in adults aged 45 to 70 years. Longitudinal data on anthropometric and hematological parameters have been obtained from physically healthy residents at the Regional Psychiatric Hospital for People with Mental Disorders in Cibórz, Lubuskie Province, Poland (142 individuals, including 68 men and 74 women). The residents who took psychoactive drugs were excluded from the study. To evaluate the studied relationships, three anthropometric traits were used and three dichotomous divisions of the study sample were made. The medians of body height, body weight, and body mass index at the age of 45 years were used to divide the sample into: shorter and taller, lighter and heavier, and slimmer and stouter individuals, respectively. Student’s t-test, Pearson’s correlation, and regression analysis were employed. The results of the present study suggest that the relationship between body size and red blood cell count is slightly more pronounced in men and its strength depends on age. However, the correlations between body size and red blood cell count proved to be weak in both sexes. With aging, the strength of the relation decreased gradually, which might have been caused by the aging-associated changes in the hematopoietic system, anemia, or was an artifact. Further studies are needed to elucidate the unclear association between body size and hematological parameters in older adults.

Influence of red blood cell-derived microparticles upon vasoregulation

Here we review recent data and the evolving understanding of the role of red blood cell-derived microparticles (RMPs) in normal physiology and in disease progression. Microparticles (MPs) are small membrane vesicles derived from various parent cell types. MPs are produced in response to a variety of stimuli through several cytoskeletal and membrane phospholipid changes. MPs have been investigated as potential biomarkers for multiple disease processes and are thought to have biological effects, most notably in: promotion of coagulation, production and handling of reactive oxygen species, immune modulation, angiogenesis, and in apoptosis. Specifically, RMPs are produced normally during RBC maturation and their production is accelerated during processing and storage for transfusion. Several factors during RBC storage are known to trigger RMP production, including: increased intracellular calcium, increased potassium leakage, and energy failure with ATP depletion. Of note, RMP composition differs from that of intact RBCs, and the nature and composition of RMP components are affected by both storage duration and the character of storage solutions. Recognised RMP bioactivities include: promotion of coagulation, immune modulation, and promotion of endothelial adhesion, as well as influence upon vasoregulation via nitric oxide (NO) scavenging. Of particular relevance, RMPs are more avid NO scavengers than intact RBCs and this feature has been proposed as a mechanism for the impaired oxygen delivery homeostasis that has been observed following transfusion. Preliminary human studies demonstrate that circulating RMP abundance increases with RBC transfusion and is associated with altered plasma vasoactivity and abnormal vasoregulation. In summary, RMPs are submicron particles released from stored RBCs, with demonstrated vasoactive properties that appear to disturb oxygen delivery homeostasis. The clinical impact of RMPs in transfusion recipients is an area of continued investigation.

Dielectric Response of Cytoplasmic Water and Its Connection to the Vitality of Human Red Blood Cells. II. The Influence of Storage

Maintaining an appropriate inventory of packaged blood products is a critical part of modern medicine. Consequently, the assessment of red blood cell (RBC) functionality is instrumental for the monitoring of the quality of stored RBC (sRBC) in the blood bank. We present a comprehensive study of sRBC lesion kinetics in SAGM (saline, adenine, glucose, mannitol) solution, using microwave dielectric spectroscopy (0.5-50 GHz) and cell deformability. As part of the research, we have isolated the microwave dielectric response of cytoplasmic water in sRBC. The extracted dielectric parameters are sensitive to the age of the cells and, in particular, to the critical moment of transition from discocyte to echinocyte. From the analysis of the dielectric relaxation as a function of storage-duration, we postulate that the behavior is rooted in the delicate interplay between bound and bulk water in the cellular interior. In particular, the microwave dielectric response reflects the moment when the continuous diffusion of oxygen to the cell and the oxygenation of hemoglobin affects the role played by water in the maintenance of cell integrity. These results open a possible new avenue for the noninvasive inspection of stored red blood cells, permitting a true inventory system for the modern blood bank.

Understanding quasi-apoptosis of the most numerous enucleated components of blood needs detailed molecular autopsy

Erythrocytes are the most numerous cells in human body and their function of oxygen transport is pivotal to human physiology. However, being enucleated, they are often referred to as a sac of molecules and their cellularity is challenged. Interestingly, their programmed death stands a testimony to their cell-hood. They are capable of self-execution after a defined life span by both cell-specific mechanism and that resembling the cytoplasmic events in apoptosis of nucleated cells. Since the execution process lacks the nuclear and mitochondrial events in apoptosis, it has been referred to as quasi-apoptosis or eryptosis. Several studies on molecular mechanisms underlying death of erythrocytes have been reported. The data has generated a non-cohesive sketch of the process. The lacunae in the present knowledge need to be filled to gain deeper insight into the mechanism of physiological ageing and death of erythrocytes, as well as the effect of age of organism on RBCs survival. This would entail how the most numerous cells in the human body die and enable a better understanding of signaling mechanisms of their senescence and premature eryptosis observed in individuals of advanced age.

Red blood cell storage time and transfusion: current practice, concerns and future perspectives

Red blood cells (RBCs) units are the most requested transfusion product worldwide. Indications for transfusion include symptomatic anaemia, acute sickle cell crisis, and acute blood loss of more than 30% of the blood volume, with the aim of restoring tissue oxygen delivery. However, stored RBCs from donors are not a qualitative equal product, and, in many ways, this is a matter of concern in the transfusion practice. Besides donor-to-donor variation, the storage time influences the RBC unit at the qualitative level, as RBCs age in the storage bag and are exposed to the so-called storage lesion. Several studies have shown that the storage lesion leads to post-transfusion enhanced clearance, plasma transferrin saturation, nitric oxide scavenging and/or immunomodulation with potential unwanted transfusion-related clinical outcomes, such as acute lung injury or higher mortality rate. While, to date, several studies have claimed the risk or deleterious effects of "old" vs "young" RBC transfusion regimes, it is still a matter of debate, and consideration should be taken of the clinical context. Transfusion-dependent patients may benefit from transfusion with "young" RBC units, as it assures longer inter-transfusion periods, while transfusion with "old" RBC units is not itself harmful. Unbiased Omics approaches are being applied to the characterisation of RBC through storage, to better understand the (patho)physiological role of microparticles (MPs) that are found naturally, and also on stored RBC units. Perhaps RBC storage time is not an accurate surrogate for RBC quality and there is a need to establish which parameters do indeed reflect optimal efficacy and safety. A better Omics characterisation of components of "young" and "old" RBC units, including MPs, donor and recipient, might lead to the development of new therapies, including the use of engineered RBCs or MPs as cell-based drug delivering tools, or cost-effective personalised transfusion strategies.

Red blood cell membrane water permeability increases with length of ex vivo storage

Water transport across the red blood cell (RBC) membrane is an essential cell function that needs to be preserved during ex vivo storage. Progressive biochemical depletion during storage can result in significant conformational and compositional changes to the membrane. Characterizing the changes to RBC water permeability can help in evaluating the quality of stored blood products and aid in the development of improved methods for the cryopreservation of red blood cells. This study aimed to characterize the water permeability (L_p), osmotically inactive fraction (b), and Arrhenius activation energy (E_a) at defined storage time-points throughout storage and to correlate the observed results with other in vitro RBC quality parameters. RBCs were collected from age- and sex-matched blood donors. A stopped flow spectrophotometer was used to determine L_p and b by monitoring changes in hemoglobin autofluorescence when RBCs were exposed to anisotonic solutions. Experimental values of L_p were characterized at three different temperatures (4, 20 and 37 °C) to determine the E_a. Results showed that L_p, b, and E_a of stored RBCs significantly increase by day 21 of storage. Degradation of the RBC membrane with length of storage was seen as an increase in hemolysis and supernatant potassium, and a decrease in deformability, mean corpuscular hemoglobin concentration and supernatant sodium. RBC osmotic characteristics were shown to change with storage and correlate with changes in RBC membrane quality metrics. Monitoring water parameters is a predictor of membrane damage and loss of membrane integrity in ex vivo stored RBCs.

Biophysical and Biochemical Markers of Red Blood Cell Fragility

BACKGROUND

Red blood cells (RBCs) undergo a natural aging process occurring in the blood circulation throughout the RBC lifespan or during routine cold storage in the blood bank. The aging of RBCs is associated with the elevation of mechanical fragility (MF) or osmotic fragility (OF) of RBCs, which can lead to cell lysis. The present study was undertaken to identify RBC properties that characterize their susceptibility to destruction under osmotic/mechanical stress.

METHODS

RBCs were isolated from freshly donated blood or units of packed RBCs (PRBCs) and suspended in albumin-supplemented phosphate-buffered saline (PBS). In addition, PRBCs were separated by filtration through a microsphere column into two fractions: enriched with rigid (R-fraction) and deformable (D-fraction) cells. The RBCs were subjected to determination of deformability, MF and OF, moreover, the level of cell surface phosphatidylserine (PS) and the stomatin level in isolated RBC membranes were measured.

RESULTS

In the RBC population, the cells that were susceptible to mechanical and osmotic stress were characterized by low deformability and increased level of surface PS. The OF/MF was higher in the R-fraction than in the D-fraction. Stomatin was depleted in destroyed cells and in the R-fraction.

CONCLUSION

RBC deformability, the levels of surface PS, and membrane stomatin can be used as markers of RBC fragility.

Endurance training alters enzymatic and rheological properties of red blood cells (RBC) in type 2 diabetic men during in vivo RBC aging

This study examines the effects of endurance training on red blood cells (RBC) in seventeen non-insulin-dependent type 2 diabetic men with a special focus on in vivo RBC aging. Venous blood was collected pre- and post-training at rest. RBC from whole blood and RBC separated according to cell age by density-gradient centrifugation were analyzed. RBC deformability was measured by ektacytometry. Immunohistochemical staining was performed to quantify the RBC-nitric oxide (NO) synthase activation (RBC-NOSSer1177) because RBC-NOS-produced NO can contribute to increased RBC deformability. The proportion of "young" RBC was significantly higher post-training. RBC deformability of all RBC (RBC of all ages) remained unaltered post-training. During RBC aging, RBC deformability decreased in both pre- and post-training. However, the training significantly increased RBC deformability in "young" and reduced their deformability in aging RBC. RBC-NOS activation remained unaltered in all RBC post-training. It tendentially increased in aging RBC pre-training, but did not change during aging post-training. The training significantly reduced RBC-NOS activation in "old" RBC. Endurance training may improve the RBC system (higher amount of "young" RBC which are more deformable). It remains speculative whether changes in older RBC (reduced RBC-NOS activation and deformability) could lead to more rapid elimination of aged RBC.

Effects of Leukoreduction and Storage on Erythrocyte Phosphatidylserine Expression and Eicosanoid Concentrations in Units of Canine Packed Red Blood Cells

Background

Storage of canine packed red blood cells (pRBCs) can increase erythrocyte phosphatidylserine (PS) expression and eicosanoid concentrations.

Hypothesis/Objectives

To determine the effects of leukoreduction on erythrocyte PS expression and eicosanoid concentrations in stored units of canine pRBCs. Our hypothesis was that leukoreduction would decrease PS expression and eicosanoid concentrations.

Animals

Eight healthy dogs.

Methods

In a cross‐over study, units of whole blood were leukoreduced (LR) or non‐LR and stored (10 and 21 days) as pRBCs. Samples were collected at donation, and before and after a simulated transfusion. PS expression was measured by flow cytometry, and concentrations of arachidonic acid (AA), prostaglandin F_2α (PGF_2α), prostaglandin E₂ (PGE₂), prostaglandin D₂ (PGD₂), thromboxane B₂ (TXB₂), 6‐keto‐prostaglandin F_1α (6‐keto‐PGF_1α), and leukotriene B₄ (LTB₄) were quantified by liquid chromatography–mass spectrometry.

Results

There was no change in PS expression during leukoreduction, storage, and simulated transfusion for non‐LR and LR units. Immediately after leukoreduction, there was a significant increase in TXB₂ and PGF_2α concentrations, but during storage, these eicosanoids decreased to non‐LR concentrations. In both LR and non‐LR units, 6‐keto‐PGF_1α concentrations increased during storage and simulated transfusion, but there was no difference between unit type. There was no difference in AA, LTB₄, PGE₂, and PGD₂ concentrations between unit types.

Conclusions and Clinical Importance

Leukoreduction, storage, and simulated transfusion do not alter erythrocyte PS expression. Leukoreduction causes an immediate increase in concentrations of TXB₂ and PGF_2α, but concentrations decrease to non‐LR concentrations with storage. Leukoreduction does not decrease the accumulation of 6‐keto‐PGF_1α during storage.

Extracellular vesicles in blood, milk and body fluids of the female and male urogenital tract and with special regard to reproduction

Extracellular vesicles (EVs) are released from almost all cells and tissues. They are able to transport substances (e.g. proteins, RNA or DNA) at higher concentrations than in their environment and may adhere in a receptor-controlled manner to specific cells or tissues in order to release their content into the respective target structure. Blood contains high concentrations of EVs mainly derived from platelets, and, at a smaller amount, from erythrocytes. The female and male reproductive tracts produce EVs which may be associated with fertility or infertility and are released into body fluids and mucosas of the urogenital organs. In this review, the currently relevant detection methods are presented and critically compared. During pregnancy, placenta-derived EVs are dynamically detectable in peripheral blood with changing profiles depending upon progress of pregnancy and different pregnancy-associated pathologies, such as preeclampsia. EVs offer novel non-invasive diagnostic tools which may reflect the situation of the placenta and the foetus. EVs in urine have the potential of reflecting urogenital diseases including cancers of the neighbouring organs. Several methods for detection, quantification and phenotyping of EVs have been established, which include electron microscopy, flow cytometry, ELISA-like methods, Western blotting and analyses based on Brownian motion. This review article summarises the current knowledge about EVs in blood and cord blood, in the different compartments of the male and female reproductive tracts, in trophoblast cells from normal and pre-eclamptic pregnancies, in placenta ex vivo perfusate, in the amniotic fluid, and in breast milk, as well as their potential effects on natural killer cells as possible targets.

Comparative studies on osmosis based encapsulation of sodium diclofenac in porcine and outdated human erythrocyte ghosts

The objective of our study was to develop controlled drug delivery system based on erythrocyte ghosts for amphiphilic compound sodium diclofenac considering the differences between erythrocytes derived from two readily available materials - porcine slaughterhouse and outdated transfusion human blood. Starting erythrocytes, empty erythrocyte ghosts and diclofenac loaded ghosts were compared in terms of the encapsulation efficiency, drug releasing profiles, size distribution, surface charge, conductivity, surface roughness and morphology. The encapsulation of sodium diclofenac was performed by an osmosis based process - gradual hemolysis. During this process sodium diclofenac exerted mild and delayed antihemolytic effect and increased potassium efflux in porcine but not in outdated human erythrocytes. FTIR spectra revealed lack of any membrane lipid disorder and chemical reaction with sodium diclofenac in encapsulated ghosts. Outdated human erythrocyte ghosts with detected nanoscale damages and reduced ability to shrink had encapsulation efficiency of only 8%. On the other hand, porcine erythrocyte ghosts had encapsulation efficiency of 37% and relatively slow drug release rate. More preserved structure and functional properties of porcine erythrocytes related to their superior encapsulation and release performances, define them as more appropriate for the usage in sodium diclofenac encapsulation process.

Addition of Sodium Pyruvate to Stored Red Blood Cells Attenuates Liver Injury in a Murine Transfusion Model

RBCs undergo numerous changes during storage and stored RBCs may induce adverse effects, ultimately resulting in organ injury in transfusion recipients. We tested the hypothesis that the addition of SP to stored RBCs would improve the quality of the stored RBCs and mitigate liver injury after transfusion in a murine model. RBCs were harvested from C57BL/6J mice and stored for 14 days in CPDA-1 containing either a solution of SP in saline or saline alone. Haemolysis, the 24-hour posttransfusion recovery, the oxygen-carrying capacity, and the SOD activity of stored RBCs were evaluated. The plasma biochemistry, hepatic MDA level, MPO activity, IL-6, TNF-α concentrations, and histopathology were measured two hours after the transfusion of stored RBCs. Compared with RBCs stored in CPDA-1 and saline, the addition of SP to stored RBCs restored their oxygen-carrying capacity and SOD activity, reduced the AST activity, BUN concentrations, and LDH activity in the plasma, and decreased the MDA level, MPO activity, and concentrations of IL-6 and TNF-α in the liver. These data indicate that the addition of SP to RBCs during storage has a beneficial effect on storage lesions in vitro and subsequently alleviates liver injury after the transfusion of stored RBCs in vivo.

Perspectives on the impact of storage duration on blood quality and transfusion outcomes

Background & Objectives

Red blood cells (RBCs) may be stored up to 42 days before transfusion, per US and EU standards. Although there is ample evidence that RBCs undergo deleterious changes during storage, studies assessing outcomes relative to storage time report conflicting findings. This study investigated RBC storage duration perspectives and practices among blood banking and transfusion professionals.

Materials & Methods

A survey was administered at the American Association of Blood Banking annual meeting in October 2014 (N = 69).

Results

On average, participants believed RBC storage should not exceed 34 days (median: 35; range: 1–52), and estimated that RBCs are typically stored 21 days before transfusion at their institutions (median: 20; range: 10–40). There was 97% agreement that minimizing/reversing changes during RBC storage may produce clinical benefits; however, 80% believed the research does not consistently demonstrate worse outcomes using older blood. Two‐thirds agreed that RBC storage duration is a major concern, but 81% agreed most institutions are not pursuing measures to shorten storage.

Conclusions

This study found that many transfusion professionals believe RBCs should be stored for fewer than the 42 days currently allowed and that further efforts are warranted to abrogate changes in stored RBCs. These findings suggest a need for increased awareness of potential consequences of extended RBC storage and for strategies to maximize transfusion benefits.

Adenosine monophosphate deaminase 3 activation shortens erythrocyte half-life and provides malaria resistance in mice

The factors that determine red blood cell (RBC) lifespan and the rate of RBC aging have not been fully elucidated. In several genetic conditions, including sickle cell disease, thalassemia, and G6PD deficiency, erythrocyte lifespan is significantly shortened. Many of these diseases are also associated with protection from severe malaria, suggesting a role for accelerated RBC senescence and clearance in malaria resistance. Here, we report a novel, N-ethyl-N-nitrosourea-induced mutation that causes a gain of function in adenosine 5'-monophosphate deaminase (AMPD3). Mice carrying the mutation exhibit rapid RBC turnover, with increased erythropoiesis, dramatically shortened RBC lifespan, and signs of increased RBC senescence/eryptosis, suggesting a key role for AMPD3 in determining RBC half-life. Mice were also found to be resistant to infection with the rodent malaria Plasmodium chabaudi. We propose that resistance to P. chabaudi is mediated by increased RBC turnover and higher rates of erythropoiesis during infection.

Past, present and forecast of transfusion medicine: What has changed and what is expected to change?

Blood transfusion is the second most used medical procedures in health care systems worldwide. Over the last few decades, significant changes have been evolved in transfusion medicine practices. These changes were mainly needed to increase safety, efficacy, and availability of blood products as well as reduce recipients' unnecessary exposure to allogeneic blood. Blood products collection, processing, and storage as well as transfusion practices throughout all patient populations were the main stream of these changes. Health care systems across the world have adopted some or most of these changes to reduce transfusion risks, to improve overall patients' outcome, and to reduce health care costs. In this article, we are going to present and discuss some of these recent modifications and their impact on patients' safety.

The effect of red blood cell transfusion on the microcirculation of anemic children

Red blood cell transfusion can improve but also might temporarily reduce the microcirculation. The buccal microcirculation was visualized and total vessel density (TVD) determined with sidestream dark field imaging in 19 pediatric anemic (Hb 7.2 g/dL, 95 % CI 6.5-7.9) oncology or hematology patients receiving red blood cell transfusions (Tx) and in 18 age-matched healthy non-anemic controls. After transfusion, Hb (8.0 g/dL, 95 % CI 7.3-8.6) and TVD increased (14.7 ± 1.7 versus 16.6 ± 2.0 mm/mm(2)) significantly with a concomitant decrease in RBC velocity in medium-sized vessels (pre-Tx 711 ± 199 versus post-Tx 627 ± 163 μm/s). Compared to the controls, pre-Tx TVD (17.5 ± 1.3 mm/mm(2)) was lower and RBC velocity (476 ± 77 μm/s) was significantly higher. After transfusion, TVD and RBC velocity remained significantly lower and higher, respectively. In a subgroup, analysis of the transfused children with infection of TVD at baseline was lower with a larger increase after transfusion compared to anemic children without infection (ΔTVD 3.4 ± 2.6 versus ΔTVD 1.3 ± 1.5 mm/mm(2)).

CONCLUSION

With the rise of hemoglobin after transfusion, significant improvements of tissue perfusion were demonstrated but differences to non-anemic controls persisted. In particular, the microcirculation of anemic oncology patients with infection improved after transfusion.

WHAT IS KNOWN

• Transfusions can improve but also temporarily reduce the microcirculation. • In neonates, transfusion significantly increases total vessel density. What is New: • Pretransfusion, the microcirculation of the anemic children differed significantly from the controls. • After transfusion, the microcirculation improved but still differed from the controls. • These changes were most profound in anemic patients with concurrent infection, therefore transfusion threshholds might need to be higher.

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.

Donor variation effect on red blood cell storage lesion: a multivariable, yet consistent, story

BACKGROUND

Previous studies have shown that baseline hematologic characteristics concerning or influencing red blood cell (RBC) properties might affect storage lesion development in individual donors. This study was conducted to evaluate whether variation in hemolysis, microparticle accumulation, phosphatidylserine (PS) exposure, and other storage lesion-associated variables might be a function of the prestorage hematologic and biologic profiles of the donor.

STUDY DESIGN AND METHODS

Ten eligible, regular blood donors were paired and studied before donation (fresh blood) and during storage of RBCs in standard blood banking conditions. Plasma and cellular characteristics and modifications were evaluated by standard laboratory and biochemical or biologic analyses as well as by statistical and network analysis tools.

RESULTS

Nitrate/nitrite and other bioactive factors exhibited high interdonor variability, which further increased during storage in a donor-specific manner. Storage lesion evaluators, including RBC fragility and PS exposure, fluctuated throughout the storage period in proportion to their values in fresh blood. Donors' levels of phosphatidylserine exposure and hemoglobin F correlated with stored cells' mean cell (RBC) Hb concentration, oxidative stress markers, and cellular fragility.

DISCUSSION

Storage lesion indicators change in an orderly fashion, namely, by following donor-related prestorage attributes. These correlations are illustrated for the first time in "prestorage versus storage" biologic networks, which might help determine the best candidates for in vivo biomarkers of storage quality and provide deeper insight into the apparently complex donor variation effect on the RBC storage lesion.

Erythropoietin reduces storage lesions and decreases apoptosis indices in blood bank red blood cells

Background

Recent evidence shows a selective destruction of the youngest circulating red blood cells (neocytolysis) trigged by a drop in erythropoietin levels.

Objective

The aim of this study was to evaluate the effect of recombinant human erythropoietin beta on the red blood cell storage lesion and apoptosis indices under blood bank conditions.

Methods

Each one of ten red blood cell units preserved in additive solution 5 was divided in two volumes of 100 mL and assigned to one of two groups: erythropoietin (addition of 665 IU of recombinant human erythropoietin) and control (isotonic buffer solution was added). The pharmacokinetic parameters of erythropoietin were estimated and the following parameters were measured weekly, for six weeks: Immunoreactive erythropoietin, hemolysis, percentage of non-discocytes, adenosine triphosphate, glucose, lactate, lactate dehydrogenase, and annexin-V/esterase activity. The t-test or Wilcoxon's test was used for statistical analysis with significance being set for a p-value <0.05.

Results

Erythropoietin, when added to red blood cell units, has a half-life >6 weeks under blood bank conditions, with persistent supernatant concentrations of erythropoietin during the entire storage period. Adenosine triphosphate was higher in the Erythropoietin Group in Week 6 (4.19 ± 0.05 μmol/L vs. 3.53 ± 0.02 μmol/L; p-value = 0.009). The number of viable cells in the Erythropoietin Group was higher than in the Control Group (77% ± 3.8% vs. 71% ± 2.3%; p-value <0.05), while the number of apoptotic cells was lower (9.4% ± 0.3% vs. 22% ± 0.8%; p-value <0.05).

Conclusions

Under standard blood bank conditions, an important proportion of red blood cells satisfy the criteria of apoptosis. Recombinant human erythropoietin beta seems to improve storage lesion parameters and mitigate apoptosis.

Microparticles variability in fresh frozen plasma: preparation protocol and storage time effects

BACKGROUND

Extracellular vesicles or microparticles exhibiting procoagulant and thrombogenic activity may contribute to the haemostatic potential of fresh frozen plasma.

MATERIALS AND METHODS

Fresh frozen plasma was prepared from platelet-rich plasma at 20 °C (Group-1 donors) or directly from whole blood at 4 °C (Group-2 donors). Each unit was aseptically divided into three parts, stored frozen for specific periods of time, and analysed by flow cytometry for procoagulant activity immediately after thaw or following post-thaw storage for 24 h at 4 °C. Donors' haematologic, biochemical and life-style profiles as well as circulating microparticles were analysed in parallel.

RESULTS

Circulating microparticles exhibited a considerable interdonor but not intergroup variation. Fresh frozen plasma units were enriched in microparticles compared to plasma in vivo. Duration of storage significantly affected platelet- and red cell-derived microparticles. Fresh frozen plasma prepared directly from whole blood contained more residual platelets and more platelet-derived microparticles compared to fresh frozen plasma prepared from platelet-rich plasma. Consequently, there was a statistically significant difference in total, platelet- and red cell-derived microparticles between the two preparation protocols over storage time in the freezer. Preservation of the thawed units for 24 h at 4 °C did not significantly alter microparticle accumulation. Microparticle accumulation and anti-oxidant capacity of fresh frozen plasma was positively or negatively correlated, respectively, with the level of circulating microparticles in individual donors.

DISCUSSION

The preparation protocol and the duration of storage in the freezer, independently and in combination, influenced the accumulation of microparticles in fresh frozen plasma units. In contrast, storage of thawed units for 24 h at 4 °C had no significant effect on the concentration of microparticles.

Restoring the youth of aged red blood cells and extending their lifespan in circulation by remodelling membrane sialic acid

Membrane sialic acid (SA) plays an important role in the survival of red blood cells (RBCs), the age-related reduction in SA content negatively impacts both the structure and function of these cells. We have therefore suggested that remodelling the SA in the membrane of aged cells would help recover cellular functions characteristic of young RBCs. We developed an effective method for the re-sialylation of aged RBCs by which the cells were incubated with SA in the presence of cytidine triphosphate (CTP) and α-2,3-sialytransferase. We found that RBCs could be re-sialylated if they had available SA-binding groups and after the re-sialylation, aged RBCs could restore their membrane SA to the level in young RBCs. Once the membrane SA was restored, the aged RBCs showed recovery of their biophysical and biochemical properties to similar levels as in young RBCs. Their life span in circulation was also extended to twofold. Our findings indicate that remodelling membrane SA not only helps restore the youth of aged RBCs, but also helps recover injured RBCs.

Time Dependent Assessment of Morphological Changes: Leukodepleted Packed Red Blood Cells Stored in SAGM

Usually packed red blood cells (pRBCs) require specific conditions in storage procedures to ensure the maximum shelf life of up to 42 days in 2-6°C. However, molecular and biochemical consequences can affect the stored blood cells; these changes are collectively labeled as storage lesions. In this study, the effect of prolonged storage was assessed through investigating morphological changes and evaluating oxidative stress. Samples from leukodepleted pRBC in SAGM stored at 4°C for 42 days were withdrawn aseptically on day 0, day 14, day 28, and day 42. Morphological changes were observed using scanning electron microscopy and correlated with osmotic fragility and hematocrit. Oxidative injury was studied through assessing MDA level as a marker for lipid peroxidation. Osmotic fragility test showed that extended storage time caused increase in the osmotic fragility. The hematocrit increased by 6.6% from day 0 to day 42. The last 2 weeks show alteration in the morphology with the appearance of echinocytes and spherocytes. Storage lesions and morphological alterations appeared to affect RBCs during the storage period. Further studies should be performed to develop strategies that will aid in the improvement of stored pRBC quality and efficacy.

Recent progress on lipid lateral heterogeneity in plasma membranes: From rafts to submicrometric domains

The concept of transient nanometric domains known as lipid rafts has brought interest to reassess the validity of the Singer-Nicolson model of a fluid bilayer for cell membranes. However, this new view is still insufficient to explain the cellular control of surface lipid diversity or membrane deformability. During the past decades, the hypothesis that some lipids form large (submicrometric/mesoscale vs nanometric rafts) and stable (>min vs s) membrane domains has emerged, largely based on indirect methods. Morphological evidence for stable submicrometric lipid domains, well-accepted for artificial and highly specialized biological membranes, was further reported for a variety of living cells from prokaryot es to yeast and mammalian cells. However, results remained questioned based on limitations of available fluorescent tools, use of poor lipid fixatives, and imaging artifacts due to non-resolved membrane projections. In this review, we will discuss recent evidence generated using powerful and innovative approaches such as lipid-specific toxin fragments that support the existence of submicrometric domains. We will integrate documented mechanisms involved in the formation and maintenance of these domains, and provide a perspective on their relevance on membrane deformability and regulation of membrane protein distribution.

Quantitative investigation of red blood cell three-dimensional geometric and chemical changes in the storage lesion using digital holographic microscopy

Quantitative phase information obtained by digital holographic microscopy (DHM) can provide new insight into the functions and morphology of single red blood cells (RBCs). Since the functionality of a RBC is related to its three-dimensional (3-D) shape, quantitative 3-D geometric changes induced by storage time can help hematologists realize its optimal functionality period. We quantitatively investigate RBC 3-D geometric changes in the storage lesion using DHM. Our experimental results show that the substantial geometric transformation of the biconcave-shaped RBCs to the spherocyte occurs due to RBC storage lesion. This transformation leads to progressive loss of cell surface area, surface-to-volume ratio, and functionality of RBCs. Furthermore, our quantitative analysis shows that there are significant correlations between chemical and morphological properties of RBCs.

Prolonged storage of packed red blood cells for blood transfusion

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Thermodynamic evaluation of vesicles shed by erythrocytes at elevated temperatures

Erythrocytes undergo structural transformation and shed small vesicles at elevated temperatures. To characterize mechanisms of the phenomenon, the Arrhenius and Eyring equations were used for analysis of the literature, experimental data on vesiculation of human and rat erythrocytes after the temperature was elevated by physical exercise or by exposure to external heat. The thermodynamic analysis of the data showed that erythrocyte transformation, vesicle release, and other associated processes are driven by entropy with enthalpy-entropy compensation. It is suggested that the physical state of the hydrated cell membrane is responsible for the compensation. The increase of vesicle number related to elevated temperatures may be indicative of the heat stress level and serve as diagnostic of erythrocyte stability and human performance.

Procoagulant phospholipid concentration in canine erythrocyte concentrates stored with or without prestorage leukoreduction

OBJECTIVE

To evaluate canine erythrocyte concentrates (ECs) for the presence of procoagulant phospholipid (PPL), determine whether PPL concentration changes during the course of storage of ECs, and ascertain whether prestorage leukoreduction (removal of leukocytes via gravity filtration) reduces the development of PPL.

SAMPLE

10 whole blood units (420 g each) collected from 10 random-source, clinically normal dogs (1 U/dog).

PROCEDURES

The dogs were randomized to 1 of 2 groups. Of the 10 whole blood units collected, 5 were processed through a standard method, and 5 underwent leukoreduction. Whole blood units were processed to generate ECs, from which aliquots were aseptically collected from each unit weekly for 5 weeks. Supernatants from the concentrates were evaluated for procoagulant activity, which was converted to PPL concentration, by use of an automated assay and by measurement of real-time thrombin generation.

RESULTS

Supernatants from stored canine ECs contained procoagulant activity as measured by both assays. In general, the PPL concentration gradually increased during the storage period, but leukoreduction reduced the development of increased procoagulant activity over time.

CONCLUSIONS AND CLINICAL RELEVANCE

The presence of PPL in canine ECs may be associated with procoagulant and proinflammatory effects in vivo, which could have adverse consequences for dogs treated with ECs.

Deficiency in mouse hyaluronidase 2: a new mechanism of chronic thrombotic microangiopathy

Hyaluronan is a major component of the extracellular matrix and glycocalyx. Its main somatic degrading enzymes are hyaluronidases 1 and 2, neither of which is active in the bloodstream. We generated hyaluronidase 2-deficient mice. These animals suffer from chronic, mild anemia and thrombocytopenia, in parallel with a 10-fold increase in plasma hyaluronan concentration. In this study we explored the mechanism of these hematologic anomalies. The decreased erythrocyte and platelet counts were attributed to peripheral consumption. The erythrocyte half-life was reduced from 25 to 8 days without signs of premature aging. Hyaluronidase 2-deficient platelets were functional. Major intrinsic defects in erythrocyte membrane or stability, as well as detrimental effects of high hyaluronan levels on erythrocytes, were ruled out in vitro. Normal erythrocytes transfused into hyaluronidase 2-deficient mice were quickly destroyed but neither splenectomy nor anti-C5 administration prevented chronic hemolysis. Schistocytes were present in blood smears from hyaluronidase 2-deficient mice at a level of 1% to 6%, while virtually absent in control mice. Hyaluronidase 2-deficient mice had increased markers of endothelial damage and microvascular fibrin deposition, without renal failure, accumulation of ultra-large multimers of von Willebrand factor, deficiency of A Disintegrin And Metalloproteinase with ThromboSpondin type 1 motifs, member 13 (ADAMTS13), or hypertension. There was no sign of structural damage in hepatic or splenic sinusoids, or in any other microvessels. We conclude that hyaluronidase 2 deficiency induces chronic thrombotic microangiopathy with hemolytic anemia in mice. The link between this uncommon condition and hyaluronidase 2 remains to be explored in humans.

Cell or cell membrane-based drug delivery systems

Natural cells have been explored as drug carriers for a long period. They have received growing interest as a promising drug delivery system (DDS) until recently along with the development of biology and medical science. The synthetic materials, either organic or inorganic, are found to be with more or less immunogenicity and/or toxicity. The cells and extracellular vesicles (EVs), are endogenous and thought to be much safer and friendlier. Furthermore, in view of their host attributes, they may achieve different biological effects and/or targeting specificity, which can meet the needs of personalized medicine as the next generation of DDS. In this review, we summarized the recent progress in cell or cell membrane-based DDS and their fabrication processes, unique properties and applications, including the whole cells, EVs and cell membrane coated nanoparticles. We expect the continuing development of this cell or cell membrane-based DDS will promote their clinic applications.

Peroxiredoxin 2, glutathione peroxidase, and catalase in the cytosol and membrane of erythrocytes under H2O2-induced oxidative stress

Erythrocytes are continuously exposed to risk of oxidative injury due to oxidant oxygen species. To prevent damage, they have antioxidant agents namely, catalase (Cat), glutathione peroxidase (GPx), and peroxiredoxin 2 (Prx2). Our aim was to contribute to a better understanding of the interplay between Prx2, Cat, and GPx under H2O2-induced oxidative stress, by studying their changes in the red blood cell cytosol and membrane, in different conditions. These three enzymes were quantified by immunoblotting. Malondialdehyde, that is, lipoperoxidation (LPO) in the erythrocyte membrane, and membrane-bound hemoglobin (MBH) were evaluated, as markers of oxidative stress. We also studied the erythrocyte membrane protein profile, to estimate how oxidative stress affects the membrane protein structure. We showed that under increasing H2O2 concentrations, inhibition of the three enzymes with or without metHb formation lead to the binding of Prx2 and GPx (but not Cat) to the erythrocyte membrane. Prx2 was detected mainly in its oxidized form and the linkage of metHb to the membrane seems to compete with the binding of Prx2. Catalase played a major role in protecting erythrocytes from high exogenous flux of H2O2, since whenever Cat was active there were no significant changes in any of the studied parameters. When only Cat was inhibited, Prx2 and GPx were unable to prevent H2O2-induced oxidative stress resulting in increasing MBH and membrane LPO. Additionally, the inhibition of one or more of these enzymes induced changes in the anchor/linker proteins of the junctional complexes of the membrane cytoskeleton-lipid bilayer, which might lead to membrane destabilization.

Increase in Red Blood Cell-Nitric Oxide Synthase Dependent Nitric Oxide Production during Red Blood Cell Aging in Health and Disease: A Study on Age Dependent Changes of Rheologic and Enzymatic Properties in Red Blood Cells

AIM

To investigate RBC-NOS dependent NO signaling during in vivo RBC aging in health and disease.

METHOD

RBC from fifteen healthy volunteers (HC) and four patients with type 2 diabetes mellitus (DM) were separated in seven subpopulations by Percoll density gradient centrifugation.

RESULTS

The proportion of old RBC was significantly higher in DM compared to HC. In both groups, in vivo aging was marked by changes in RBC shape and decreased cell volume. RBC nitrite, as marker for NO, was higher in DM and increased in both HC and DM during aging. RBC deformability was lower in DM and significantly decreased in old compared to young RBC in both HC and DM. RBC-NOS Serine1177 phosphorylation, indicating enzyme activation, increased during aging in both HC and DM. Arginase I activity remained unchanged during aging in HC. In DM, arginase I activity was significantly higher in young RBC compared to HC but decreased during aging. In HC, concentration of L-arginine, the substrate of RBC-NOS and arginase I, significantly dropped from young to old RBC. In DM, L-arginine concentration was significantly higher in young RBC compared to HC and significantly decreased during aging. In blood from healthy subjects, RBC-NOS activation was additionally inhibited by N5-(1-iminoethyl)-L-Ornithine dihydrochloride which decreased RBC nitrite, and impaired RBC deformability of all but the oldest RBC subpopulation.

CONCLUSION

This study first-time showed highest RBC-NOS activation and NO production in old RBC, possibly to counteract the negative impact of cell shrinkage on RBC deformability. This was even more pronounced in DM. It is further suggested that highly produced NO only insufficiently affects cell function of old RBC maybe because of isolated RBC-NOS in old RBC thus decreasing NO bioavailability. Thus, increasing NO availability may improve RBC function and may extend cell life span in old RBC.

Quantifying morphological heterogeneity: a study of more than 1 000 000 individual stored red blood cells

BACKGROUND AND OBJECTIVES

The morphology of red blood cells (RBCs) deteriorates progressively during hypothermic storage. The degree of deterioration varies between individual cells, resulting in a highly heterogeneous population of cells contained within each RBC unit. Current techniques capable of categorizing the morphology of individual stored RBCs are manual, laborious and error-prone procedures that limit the number of cells that can be studied. Our objective was to create a simple, automated system for high-throughput RBC morphology classification.

MATERIALS AND METHODS

A simple microfluidic device, designed to enable rapid, consistent acquisition of images of optimally oriented RBCs, was fabricated using soft lithography. A custom image analysis algorithm was developed to categorize the morphology of each individual RBC in the acquired images. The system was used to determine morphology of individual RBCs in several RBC units stored hypothermically for 6-8 weeks.

RESULTS

The system was used to automatically determine the distribution of cell diameter within each morphological class for >1 000 000 individual stored RBCs (speed: >10 000 cells/h; accuracy: 91·9% low resolution, 75·3% high resolution). Diameter mean and standard deviation by morphology class were as follows: discocyte 7·80 ± 0·49 μm, echinocyte 1 7·61 ± 0·63 μm, echinocyte 2 7·02 ± 0·61 μm, echinocyte 3 6·47 ± 0·42 μm, sphero-echinocyte 6·01 ± 0·26 μm, spherocyte 6·02 ± 0·27 μm, stomatocyte 1 6·95 ± 0·61 μm and stomatocyte 2 7·32 ± 0·47 μm.

CONCLUSIONS

The automated morphology classification procedure described in this study is significantly simpler, faster and less subjective than conventional manual procedures. The ability to evaluate the morphology of individual RBCs automatically, rapidly and in statistically significant numbers enabled us to perform the most extensive study of stored RBC morphology to date.

Propensity of red blood cells to undergo P2X7 receptor-mediated phosphatidylserine exposure does not alter during in vivo or ex vivo aging

BACKGROUND

Phosphatidylserine (PS) exposure facilitates the removal of red blood cells (RBCs) from the circulation, potentially contributing to the loss of stored RBCs after transfusion, as well as senescent RBCs. Activation of the P2X7 receptor by extracellular adenosine 5'-triphosphate (ATP) can induce PS exposure on freshly isolated human RBCs, but whether this process occurs in stored RBCs or changes during RBC aging is unknown.

STUDY DESIGN AND METHODS

RBCs were processed and stored according to Australian blood banking guidelines. PS exposure was determined by annexin V binding and flow cytometry. Efficacy of P2X antagonists was assessed by flow cytometric measurements of ATP-induced ethidium+ uptake in RPMI 8226 cells. Osmotic fragility was assessed by lysis in hypotonic saline. RBCs were fractionated by discontinuous density centrifugation.

RESULTS

ATP (1 mmol/L) induced PS exposure on RBCs stored for less than 1 week. This process was near-completely inhibited by the P2X7 antagonists A438079 and AZ10606120 and the P2X1/P2X7 antagonist MRS2159 but not the P2X1 antagonist NF499. ATP-induced PS exposure on RBCs was not dependent on K+, Na+, or Cl- fluxes. ATP did not alter the osmotic fragility of stored RBCs. ATP-induced PS exposure was similar between RBCs of different densities. ATP-induced PS exposure was also similar between RBCs stored for less than 1 week or for 6 weeks.

CONCLUSION

The propensity of RBCs to undergo P2X7-mediated PS exposure does not alter during in vivo and ex vivo aging. Thus, P2X7 activation is unlikely to be involved in the removal of senescent RBCs or stored RBCs after transfusion.