Erythrocyte ageingin vivoandin vitro: structural aspects and implications for transfusion

Perioperative Blood Transfusions and Cancer Progression: A Narrative Review

PURPOSE OF REVIEW

To examine the most recent evidence about known controversies on the effect of perioperative transfusion on cancer progression.

RECENT FINDINGS

Laboratory evidence suggests that transfusion-related immunomodulation can be modified by blood management and storage practices, but it is likely of less intensity than the effect of the surgical stress response. Clinical evidence has questioned the independent effect of blood transfusion on cancer progression for some cancers but supported it for others. Despite major changes in surgery and anesthesia, cancer surgery remains a major player in perioperative blood product utilization. Prospective data is still required to strengthen or refute existing associations. Transfusion-related immunomodulation in cancer surgery is well-documented, but the extent to which it affects cancer progression is unclear. Associations between transfusion and cancer progression are disease-specific. Increasing evidence shows autologous blood transfusion may be safe in cancer surgery.

Differential Responses of Young and Old Erythrocytes Stored with Vitamin C and Vitamin E in Additive Solution-7

Oxidative stress (OS) causes biochemical and morphological alterations in erythrocytes. The primary factors contributing to OS are aging and storage. Antioxidants significantly alleviate OS. Therefore, this study aimed to investigate the response of young and old erythrocytes to vitamin C and vitamin E during storage. Erythrocytes were separated into young and old by the Percoll method. Each erythrocyte subpopulation was categorized into the i) Control (additive solution-7 [AS-7]) and ii) vitamin C and vitamin E in AS-7 (VC+VE) groups and stored for 21 days at 4°C. OS, antioxidant, and aging markers were analyzed on days 1, 14, and 21. The activity of antioxidant enzymes was similar throughout storage in young cells. However, superoxide dismutase activity elevated in old cells (Control and VC+VE) on days 1 and 21. Catalase (CAT) activity increased on days 14 and 21, whereas glutathione peroxidase (GPX) increased on days 1 and 14 in old Controls. However, in old VC+VE, CAT increased on day 21 and GPX increased on day 1. Advanced oxidation protein products, superoxides, glutathione, and uric acid increased in old cells throughout storage. Malondialdehyde decreased in old VC+VE compared with old Control on days 14 and 21. Sialic acids and glutamate oxaloacetate transaminase activity were higher in young cells compared to old cells. Young cells exhibited lower oxidative changes throughout storage. Vitamin C and vitamin E were effective in maintaining the redox balance in old cells. These findings emphasize the need for specific approaches for different subpopulations during erythrocyte banking.

Towards the crux of sex-dependent variability in red cell concentrates

Donor sex can alter the RBC 'storage lesion' progression, contributing to dissimilarities in blood product quality, and thus adverse post-transfusion reactions. The mechanisms underlying the reduced sensitivity of female RBCs to storage-induced stress are partially ascribed to the differential effects of testosterone, progesterone, and estrogen on hemolytic propensity. Contributing to this is the increased proportion of more robust, biologically 'young' subpopulations of RBCs in females. Herein, we discuss the impact of sex hormones on RBCs and the relevance of these biological subpopulations to provide further insight into sex-dependent blood product variability.

Dielectrophoretic profiling of erythrocytes to study the impacts of metabolic stress, temperature, and storage duration utilizing a point-and-planar microdevice

Dielectrophoresis (DEP) is widely utilized for trapping and sorting various types of cells, including live and dead cells and healthy and infected cells. This article focuses on the dielectric characterization of erythrocytes (red blood cells or RBCs) by quantifying DEP crossover frequency using a novel point-and-planar microwell device platform. Numerical simulations using COMSOL Multiphysics software demonstrate that the distribution of the DEP force is influenced by factors such as the shape of the point electrode, spacing between the point and planar electrodes, and the type of bioparticle being investigated. The dependency on electrode spacing is experimentally evaluated by analyzing the DEP crossover response of erythrocytes. Furthermore, the results are validated against the traditional electrical characterization technique called electrorotation, which typically requires laborious fabrication and operation using quadrupole electrodes. Other significant factors, including erythrocyte storage age and the changes in cell properties over time since collection, osmolarity, and temperature, are also assessed to determine the optimal conditions for erythrocyte characterization. The findings indicate a significant difference between fresh and stored erythrocyte samples (up to 4 days), highlighting the importance of maintaining an isotonic medium for cell storage.

Study protocol of the WashT Trial: transfusion with washed versus unwashed red blood cells to reduce morbidity and mortality in infants born less than 28 weeks' gestation - a multicentre, blinded, parallel group, randomised controlled trial

INTRODUCTION

Many extremely preterm newborns develop anaemia requiring a transfusion, with most receiving three to five transfusions during their admission. While transfusions save lives, the potential for transfusion-related adverse outcomes is an area of growing concern. Transfusion is an independent predictor of death and is associated with increased morbidity, length of hospital stay, risk of infection and immune modulation. The underlying mechanisms include adverse pro-inflammatory and immunosuppressive responses. Evidence supports an association between transfusion of washed red cells and fewer post-transfusion complications potentially through removal of chemokines, lipids, microaggregates and other biological response modifiers. However, the clinical and cost-effectiveness of washed cells have not been determined.

METHODS AND ANALYSIS

This is a multicentre, randomised, double-blinded trial of washed versus unwashed red cells. Infants <28 weeks' gestation requiring a transfusion will be enrolled. Transfusion approaches will be standardised within each study centre and will occur as soon as possible with a recommended fixed transfusion volume of 15 mL/kg whenever the haemoglobin is equal to or falls below a predefined restrictive threshold, or when clinically indicated. The primary outcome is a composite of mortality and/or major morbidity to first discharge home, defined as one or more of the following: physiologically defined bronchopulmonary dysplasia; unilateral or bilateral retinopathy of prematurity grade >2, and; necrotising enterocolitis stage ≥2. To detect a 10% absolute reduction in the composite outcome from 69% with unwashed red blood cell (RBCs) to 59% with washed RBCs with 90% power, requires a sample size of 1124 infants (562 per group). Analyses will be performed on an intention-to-treat basis with a prespecified statistical analysis plan. A cost-effectiveness analysis will also be undertaken.

ETHICS AND DISSEMINATION

Ethics approval has been obtained from the Women's and Children's Health Network Human Research Ethics Committee (HREC/12/WCHN/55). The study findings will be disseminated through peer-reviewed articles and conferences.

TRIAL REGISTRATION NUMBER

ACTRN12613000237785 Australian New Zealand Clinical Trials Registry.

Timing of Blood Transfusions and 30-Day Patient Outcomes After Coronary Artery Bypass Graft Surgery

OBJECTIVE

Packed red blood cell transfusion during coronary artery bypass graft surgery is known to be associated with adverse outcomes. However, the association of the timing between transfusions in relation to discharge and 30-day postoperative outcomes has not been studied. The study authors investigated the impact of transfusion timing on 30-day surgical outcomes.

DESIGN

A retrospective review.

SETTING

At a single tertiary-care academic hospital.

PARTICIPANTS

A total of 2,481 adult patients underwent primary coronary artery bypass graft surgery between January 2014 and December 2020.

MEASUREMENTS AND MAIN RESULTS

The relationship between the timing of packed red blood cell transfusion (intraoperative, postoperative, or both) and 30-day postoperative outcome variables was calculated as an odds ratio. The influence of timing of transfusion on adjusted probability of postoperative complications was plotted against the lowest intraoperative hematocrit. The median age of the population was 67 years (60.0-74.0), body mass index was 28.5 (25.6-32.3) kg/m², and 497 (20.0%) were female. A total of 1,588 (36%) patients received packed red blood cell transfusions; 182 (7.3%) received intraoperative transfusions, 489 (19.7%) received postoperative transfusions, and 222 (9.0%) received both (intraoperative and postoperative transfusions). Postoperative transfusion was associated with significantly higher odds of readmission (1.83 [1.32-2.54], p = 0.002) and heart failure (1.64 [1.2-2.23], p = 0.008) compared to patients with no transfusions; whereas intraoperative transfusions were not.

CONCLUSION

The authors' data suggested that the postoperative timing of transfusion in patients undergoing coronary artery bypass graft surgery may be associated with an increased incidence of 30-day heart failure and readmission. Prospective research is needed to conclusively confirm these findings.

Intermittent scavenging of storage lesion from stored red blood cells by electrospun nanofibrous sheets enhances their quality and shelf-life

Transfusion of healthy red blood cells (RBCs) is a lifesaving process. However, upon storing RBCs, a wide range of damage-associate molecular patterns (DAMPs), such as cell-free DNA, nucleosomes, free-hemoglobin, and poly-unsaturated-fatty-acids are generated. DAMPs can further damage RBCs; thus, the quality of stored RBCs declines during the storage and limits their shelf-life. Since these DAMPs consist of either positive or negative charged species, we developed taurine and acridine containing electrospun-nanofibrous-sheets (Tau-AcrNFS), featuring anionic, cationic charges and an DNA intercalating group on their surfaces. We show that Tau-AcrNFS are efficient in scavenging DAMPs from stored human and mice RBCs ex vivo. We find that intermittent scavenging of DAMPs by Tau-AcrNFS during the storage reduces the loss of RBC membrane integrity and reduces discocytes-to-spheroechinocytes transformation in stored-old-RBCs. We perform RBC-transfusion studies in mice to reveal that intermittent removal of DAMPs enhances the quality of stored-old-RBCs equivalent to freshly collected RBCs, and increases their shelf-life by ~22%. Such prophylactic technology may lead to the development of novel blood bags or medical device, and may therefore impact healthcare by reducing transfusion-related adverse effects.

Methodologies and tools to shed light on erythrophagocytosis

Red blood cells (RBC) are the most abundant circulating cell of the human body. RBC are constantly exposed to multiple stresses in the circulation, leading to molecular and structural impairments and death. The physiological process of RBC senescence or ageing is referred to as eryptosis. At the end of their lifespan, aged RBC are recognized and removed from the blood by professional phagocytes via a phenomenon called erythrophagocytosis (EP); the phagocytosis of RBC. Some genetic and acquired diseases can influence eryptosis, thereby affecting RBC lifespan and leading to hemolytic anemia. In some diseases, such as diabetes and atherosclerosis, eryptosis and EP can participate in disease progression with both professional and non-professional phagocytes. Therefore, investigating the process of EP in vivo and in vitro, as well as in different cell types, will not only contribute to the understanding of the physiological steps of EP, but also to the deciphering of the specific mechanisms involving RBC and EP that underlie certain pathologies. In this review, the process of EP is introduced and the different methods for studying EP are discussed together with examples of the experimental procedures and materials required.

Oxidation Stress as a Mechanism of Aging in Human Erythrocytes: Protective Effect of Quercetin

Aging is a multi-factorial process developing through a complex net of interactions between biological and cellular mechanisms and it involves oxidative stress (OS) as well as protein glycation. The aim of the present work was to verify the protective role of Quercetin (Q), a polyphenolic flavonoid compound, in a d-Galactose (d-Gal)-induced model of aging in human erythrocytes. The anion-exchange capability through the Band 3 protein (B3p) measured by the rate constant of the SO₄²⁻ uptake, thiobarbituric acid reactive substances (TBARS) levels—a marker of lipid peroxidation—total sulfhydryl (-SH) groups, glycated hemoglobin (A1c), and a reduced glutathione/oxidized glutathione (GSH-GSSG) ratio were determined following the exposure of erythrocytes to 100 mM d-Gal for 24 h, with or without pre-incubation with 10 µM Q. The results confirmed that d-Gal activated OS pathways in human erythrocytes, affecting both membrane lipids and proteins, as denoted by increased TBARS levels and decreased total sulfhydryl groups, respectively. In addition, d-Gal led to an acceleration of the rate constant of the SO₄²⁻ uptake through the B3p. Both the alteration of the B3p function and oxidative damage have been improved by pre-treatment with Q, which preferentially ameliorated lipid peroxidation rather than protein oxidation. Moreover, Q prevented glycated A1c formation, while no protective effect on the endogenous antioxidant system (GSH-GSSG) was observed. These findings suggest that the B3p could be a novel potential target of antioxidant treatments to counteract aging-related disturbances. Further studies are needed to confirm the possible role of Q in pharmacological strategies against aging.

Red Blood Cell Extracellular Vesicle-Based Drug Delivery: Challenges and Opportunities

Recently, red blood cell-derived extracellular vesicles (RBCEVs) have attracted attention for clinical applications because of their safety and biocompatibility. RBCEVs can escape macrophages through the binding of CD47 to inhibitory receptor signal regulatory protein α. Furthermore, genetic materials such as siRNA, miRNA, mRNA, or single-stranded RNA can be encapsulated within RBCEVs and then released into target cells for precise treatment. However, their side effects, half-lives, target cell specificity, and limited large-scale production under good manufacturing practice remain challenging. In this review, we summarized the biogenesis and composition of RBCEVs, discussed the advantages and disadvantages of RBCEVs for drug delivery compared with synthetic nanovesicles and non-red blood cell-derived EVs, and provided perspectives for overcoming current limitations to the use of RBCEVs for clinical applications.

Blood bank storage of red blood cells increases RBC cytoplasmic membrane order and bending rigidity

Blood banks around the world store blood components for several weeks ensuring its availability for transfusion medicine. Red blood cells (RBCs) are known to undergo compositional changes during storage, which may impact the cells' function and eventually the recipients' health. We extracted the RBC's cytoplasmic membrane (RBCcm) to study the effect of storage on the membranes' molecular structure and bending rigidity by a combination of X-ray diffraction (XRD), X-ray diffuse scattering (XDS) and coarse grained Molecular Dynamics (MD) simulations. Blood was stored in commercial blood bags for 2 and 5 weeks, respectively and compared to freshly drawn blood. Using mass spectrometry, we measured an increase of fatty acids together with a slight shift towards shorter tail lengths. We observe an increased fraction (6%) of liquid ordered (lo) domains in the RBCcms with storage time, and an increased lipid packing in these domains, leading to an increased membrane thickness and membrane order. The size of both, lo and liquid disordered (ld) lipid domains was found to decrease with increased storage time by up to 25%. XDS experiments reveal a storage dependent increase in the RBCcm's bending modulus κ by a factor of 2.8, from 1.9 kBT to 5.3 kBT. MD simulations were conducted in the absence of proteins. The results show that the membrane composition has a small contribution to the increased bending rigidity and suggests additional protein-driven mechanisms.

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.

Storage-Related Changes in Autologous Whole Blood and Irradiated Allogeneic Red Blood Cells and Their Ex Vivo Effects on Deformability, Indices, and Density of Circulating Erythrocytes in Patients Undergoing Cardiac Surgery With Cardiopulmonary Bypass

OBJECTIVES

Blood-processing techniques and preservation conditions cause storage lesions, possibly leading to adverse outcomes after transfusion. The authors investigated the metabolic changes and deformability of red blood cells (RBCs) during storage and determined the effect of storage lesions on circulating RBCs during cardiac surgery.

DESIGN

Prospective study.

SETTING

Tertiary care center affiliated with a university hospital.

PARTICIPANTS

Adults who underwent elective cardiac surgery requiring cardiopulmonary bypass.

INTERVENTIONS

The authors collected aliquots of autologous and irradiated allogeneic RBCs and blood samples from seven patients who received autologous whole blood and nine patients who received irradiated allogeneic RBCs before incision (baseline), at the start and end of cardiopulmonary bypass, and at completion of surgery.

MEASUREMENTS AND MAIN RESULTS

The authors analyzed RBC deformability, erythrocyte indices, and density distribution to evaluate blood banking-induced alterations of autologous and allogeneic RBCs and changes in circulating RBCs in recipients, after blood transfusion. Time-dependent biochemical changes and significant decreases in deformability during storage occurred in both groups; however, homologous RBCs had significantly lower deformability than autologous RBCs. Trends in mean corpuscular volume and mean corpuscular hemoglobin concentration differed in both groups. In the homologous transfusion group, during cardiac surgery, RBC deformability, mean corpuscular volume, and mean corpuscular hemoglobin concentration showed significant changes compared with baseline values, and a greater number of denser subpopulations was observed at surgery completion.

CONCLUSIONS

Blood-processing techniques contribute to storage lesions, suggesting that transfusion of autologous whole blood, rather than allogeneic RBCs, could maintain the ability of circulating RBCs to deform and lead to potentially better transfusion outcomes.

An Insight into the Stages of Ion Leakage during Red Blood Cell Storage

Packed red blood cells (pRBCs), the most commonly transfused blood product, are exposed to environmental disruptions during storage in blood banks. In this study, temporal sequence of changes in the ion exchange in pRBCs was analyzed. Standard techniques commonly used in electrolyte measurements were implemented. The relationship between ion exchange and red blood cells (RBCs) morphology was assessed with use of atomic force microscopy with reference to morphological parameters. Variations observed in the Na⁺, K⁺, Cl⁻, H⁺, HCO₃⁻, and lactate ions concentration show a complete picture of singly-charged ion changes in pRBCs during storage. Correlation between the rate of ion changes and blood group type, regarding the limitations of our research, suggested, that group 0 is the most sensitive to the time-dependent ionic changes. Additionally, the impact of irreversible changes in ion exchange on the RBCs membrane was observed in nanoscale. Results demonstrate that the level of ion leakage that leads to destructive alterations in biochemical and morphological properties of pRBCs depend on the storage timepoint.

The Redox Balance and Membrane Shedding in RBC Production, Maturation, and Senescence

Membrane shedding in the form of extracellular vesicles plays a key role in normal physiology and pathology. Partial disturbance of the membrane-cytoskeleton linkage and increased in the intracellular Ca content are considered to be mechanisms underlying the process, but it is questionable whether they constitute the primary initiating steps. Homeostasis of the redox system, which depends on the equilibrium between oxidants and antioxidants, is crucial for many cellular processes. Excess oxidative power results in oxidative stress, which affects many cellular components, including the membrane. Accumulating evidence suggests that oxidative stress indirectly affects membrane shedding most probably by affecting the membrane-cytoskeleton and the Ca content. In red blood cells (RBCs), changes in both the redox system and membrane shedding occur throughout their life-from birth-their production in the bone marrow, to death-aging in the peripheral blood and removal by macrophages in sites of the reticuloendothelial system. Both oxidative stress and membrane shedding are disturbed in diseases affecting the RBC, such as the hereditary and acquired hemolytic anemias (i.e., thalassemia, sickle cell anemia, and autoimmune hemolytic anemia). Herein, I review some data-based and hypothetical possibilities that await experimental confirmation regarding some aspects of the interaction between the redox system and membrane shedding and its role in the normal physiology and pathology of RBCs.

Red Blood Cell Contribution to Hemostasis

Red Blood Cells (RBCs) have been increasingly recognized to play important roles in hemostasis and the mechanisms by which they do so continue to be elucidated. First and foremost, RBC biomechanics are the principal determinant of viscosity and flow dynamics of blood, which strongly influence all features of hemostasis. Of note, morphologic pathology, such as that found in sickle cell disease, leads to increased risk of thrombotic disease. RBC surface interactions govern signaling between platelets and RBCs and also aid in the conversion of prothrombin to thrombin. Additionally, RBCs generate microparticles which have been shown to reduce clotting time. Finally, blood clot structure and maturation are dependent on the inclusion of RBCs in forming thrombi. Here, we review the above mechanisms of RBC contribution to hemostasis.

Metabolic rejuvenation upgrades circulatory functions of red blood cells stored under blood bank conditions

BACKGROUND

Red blood cells (RBC) change upon hypothermic conservation, and storage for 6 weeks is associated with the short-term clearance of 15% to 20% of transfused RBCs. Metabolic rejuvenation applied to RBCs before transfusion replenishes energetic sources and reverses most storage-related alterations, but how it impacts RBC circulatory functions has not been fully elucidated.

STUDY DESIGN AND METHODS

Six RBC units stored under blood bank conditions were analyzed weekly for 6 weeks and rejuvenated on Day 42 with an adenine-inosine-rich solution. Impact of storage and rejuvenation on adenosine triphosphate (ATP) levels, morphology, accumulation of storage-induced microerythrocytes (SMEs), elongation under an osmotic gradient (by LORRCA), hemolysis, and phosphatidylserine (PS) exposure was evaluated. The impact of rejuvenation on filterability and adhesive properties of stored RBCs was also assessed.

RESULTS

Rejuvenation of RBCs restored intracellular ATP to almost normal levels and decreased the PS exposure from 2.78% to 0.41%. Upon rejuvenation, the proportion of SME dropped from 28.2% to 9.5%, while the proportion of normal-shaped RBCs (discocytes and echinocytes 1) increased from 47.7% to 67.1%. In LORCCA experiments, rejuvenation did not modify the capacity of RBCs to elongate and induced a reduction in cell volume. In functional tests, rejuvenation increased RBC filterability in a biomimetic splenic filter (+16%) and prevented their adhesion to endothelial cells (-87%).

CONCLUSION

Rejuvenation reduces the proportion of morphologically altered and adhesive RBCs that accumulate during storage. Along with the improvement in their filterability, these data show that rejuvenation improves RBC properties related to their capacity to persist in circulation after transfusion.

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.

Sex-related aspects of the red blood cell storage lesion

BACKGROUND

Several factors contribute to the manifestation of red blood cell (RBC) storage lesions, with one of the most interesting being the "donor variation effect". Since many haematological characteristics of blood donors are sex-dependent, sex hormones and their age-dependent variation may affect the storage profile of RBCs.

MATERIALS AND METHODS

Fresh blood from 200 healthy male and female donors underwent haematological, biochemical and physiological analysis. Three selected groups of donors (men, n=8; pre-menopausal women, n=8; and post-menopausal women, n=4) exhibiting as similar as possible baseline values were recruited for blood donation in leukoreduced CPD/SAGM units. RBC indices, haemolysis and propensity for haemolysis, reactive oxygen species (ROS) and plasma antioxidant capacity were measured bi-weekly.

RESULTS

Female blood was characterised by lower plasma antioxidant capacity and free haemoglobin (Hb) levels in vivo, in spite of the higher RBC osmotic fragility, compared to male blood. Comparatively low Hb concentration was also measured in stored RBCs from female donors, as in vivo. Mean corpuscular Hb (MCH), mean corpuscular Hb concentration (MCHC), and plasma antioxidant capacity were also lower in female donors throughout storage, even though baseline levels were equal to those of the male group. There was no difference in propensity of stored RBCs for haemolysis between male and female units but intracellular ROS levels were significantly lower in female RBCs. Increased end-of-storage extracellular potassium and recruitment of protein stress markers (clusterin, Hb) to the RBC membrane were observed in the units of post- vs pre-menopausal female donors at mid-storage onwards.

DISCUSSION

Donor's sex has an impact on Hb concentration and redox parameters of stored RBCs. In addition, menopause seems to promote RBC membrane remodelling, at least during prolonged storage. Our pilot study provides new insights on the different effects on RBC storage lesion according to sex.

Donor-dependent aging of young and old red blood cell subpopulations: Metabolic and functional heterogeneity

BACKGROUND

Characteristics of red blood cells (RBCs) are influenced by donor variability. This study assessed quality and metabolomic variables of RBC subpopulations of varied biologic age in red blood cell concentrates (RCCs) from male and female donors to evaluate their contribution to the storage lesion.

STUDY DESIGN AND METHODS

Red blood cell concentrates from healthy male (n = 6) and female (n = 4) donors were Percoll separated into less dense ("young", Y-RCCs) and dense ("old", O-RCCs) subpopulations, which were assessed weekly for 28 days for changes in hemolysis, mean cell volume (MCV), hemoglobin concentration (MCHC), hemoglobin autofluorescence (HGB), morphology index (MI), oxygen affinity (p50), rigidity, intracellular reactive oxygen species (ROS), calcium ([Ca²⁺ ]), and mass spectrometry-based metabolomics.

RESULTS

Young RCCs having disc-to-discoid morphology showed higher MCV and MI, but lower MCHC, HGB, and rigidity than O-RCCs, having discoid-to-spheroid shape. By Day 14, Y-RCCs retained lower hemolysis and rigidity and higher p50 compared to O-RCCs. Donor sex analyses indicated that females had higher MCV, HGB, ROS, and [Ca²⁺ ] and lower hemolysis than male RBCs, in addition to having a decreased rate of change in hemolysis by Day 28. Metabolic profiling indicated a significant sex-related signature across all groups with increased markers of high membrane lipid remodeling and antioxidant capacity in Y-RCCs, whereas O-RCCs had increased markers of oxidative stress and decreased coping capability.

CONCLUSION

The structural, functional, and metabolic dissimilarities of Y-RCCs and O-RCCs from female and male donors demonstrate RCC heterogeneity, where RBCs from females contribute less to the storage lesion and age slower than males.

Influence of AS-7 on the storage lesion in young and old circulating erythrocytes

Blood and its components are stored to meet the demands of blood transfusion. Erythrocytes undergo progressive modifications during storage known as storage lesions. Storage solutions were developed to improve shelf life and extend red cell viability. Therefore, the objective of this study is to analyze the effects of AS-7 on young and old erythrocytes during storage. Blood was collected from the blood bank at Kempegowda Institute of Medical Sciences (KIMS) hospital, Bengaluru. Erythrocytes were isolated from whole blood and separated based on its age using Percoll density gradient. The young and old erythrocytes were stored in AS-7 for 35 days and every 5th day, oxidative stress markers - Hemoglobin (Hb), Oxidative Hemolysis, Mechanical Fragility, Sialic Acid, Superoxides, Glucose, Lactate Dehydrogenase (LDH), Glutathione, antioxidant capacity (TAC_CUPRAC), Plasma Membrane Redox System (PMRS), antioxidant enzymes, lipid peroxidation, and protein oxidation products were assessed. Hb, glucose, TAC_CUPRAC, and superoxide dismutase reduced, while oxidative hemolysis, mechanical fragility, protein oxidation, and lipid peroxidation products increased in young and old cells over storage. LDH, PMRS, catalase, advanced oxidation protein products, and conjugate dienes were significant in old cells from day 5 itself, whereas in young cells towards the end of storage (from day 25). Oxidative insult was higher in old cells compared to young cells. AS-7 was beneficial to young erythrocytes during storage and thus laying the foundation for the possibilities of utilizing young cells as models for storage studies.

Past, Present, and Future of Affinity-based Cell Separation Technologies

Progress in cell purification technology is critical to increase the availability of viable cells for therapeutic, diagnostic, and research applications. A variety of techniques are now available for cell separation, ranging from non-affinity methods such as density gradient centrifugation, dielectrophoresis, and filtration, to affinity methods such as chromatography, two-phase partitioning, and magnetic-/fluorescence-assisted cell sorting. For clinical and analytical procedures that require highly purified cells, the choice of cell purification method is crucial, since every method offers a different balance between yield, purity, and bioactivity of the cell product. For most applications, the requisite purity is only achievable through affinity methods, owing to the high target specificity that they grant. In this review, we discuss past and current methods for developing cell-targeting affinity ligands and their application in cell purification, along with the benefits and challenges associated with different purification formats. We further present new technologies, like stimuli-responsive ligands and parallelized microfluidic devices, towards improving the viability and throughput of cell products for tissue engineering and regenerative medicine. Our comparative analysis provides guidance in the multifarious landscape of cell separation techniques and highlights new technologies that are poised to play a key role in the future of cell purification in clinical settings and the biotech industry. STATEMENT OF SIGNIFICANCE: Technologies for cell purification have served science, medicine, and industrial biotechnology and biomanufacturing for decades. This review presents a comprehensive survey of this field by highlighting the scope and relevance of all known methods for cell isolation, old and new alike. The first section covers the main classes of target cells and compares traditional non-affinity and affinity-based purification techniques, focusing on established ligands and chromatographic formats. The second section presents an excursus of affinity-based pseudo-chromatographic and non-chromatographic technologies, especially focusing on magnetic-activated cell sorting (MACS) and fluorescence-activated cell sorting (FACS). Finally, the third section presents an overview of new technologies and emerging trends, highlighting how the progress in chemical, material, and microfluidic sciences has opened new exciting avenues towards high-throughput and high-purity cell isolation processes. This review is designed to guide scientists and engineers in their choice of suitable cell purification techniques for research or bioprocessing needs.

Elastic hysteresis loop acts as cell deformability in erythrocyte aging

The decrease in cellular deformability shows strong correlation with erythrocyte aging. Cell deformation can be divided into passive deformation and active deformation; however, the active deformation has been ignored in previous studies. In this work, Young's moduli of age-related erythrocytes were tested by atomic force microscopy. Furthermore, the deformation and passive and active deformation values were calculated by respective areas. Our results showed that erythrocytes in the densest fraction had the highest values of the Young's modulus, deformation, and active deformation, but the lowest values of passive deformation. Moreover, values of the deformation and active deformation both increased gradually with erythrocyte aging. The present data indicate that the elastic hysteresis loop between the approach and the retract curve could be regarded as erythrocyte deformability, and cellular deformability could be characterized by energy states. In addition, active deformation might be a crucial mechanical factor for clearing aged erythrocytes. This could provide an important information on erythrocyte biomechanics in the removal of aged cell.

Evaluation of hematologic, biochemical, and blood gas variables in stored canine packed red blood cells, and the impact of storage time on blood recipients

BACKGROUND

Canine packed red blood cells (pRBCs) can be stored under refrigeration for several days; however, cellular metabolism remains active inside the units, thus producing substances that affect their quality.

OBJECTIVES

We aimed to evaluate hematologic, biochemical, and blood gas variable alterations that occur in canine pRBCs during storage, and their effects on recipient clinicopathologic parameters.

METHODS

The study was conducted in two phases. In phase I, 15 pRBC units containing CPDA-1 were stored for 28 days; samples were collected weekly from the units of days 0 to 28 to measure the packed cell volume (PCV), pH, partial pressure carbon dioxide (PCO₂ ), partial pressure oxygen (PO₂ ), concentrations of lactate and potassium, and the percent hemolysis. In phase II, another 22 canine pRBC units stored for different time periods (maximum of 21 days) were transfused, and the recipients were evaluated before and after transfusion for changes in clinical parameters (heart rate, respiratory rate, systolic arterial pressure, and rectal temperature) and hematologic variables (PCV, lactate and potassium concentrations, pH, PCO₂ , the ratio of arterial oxygen partial pressure to fractional inspired oxygen [PO₂ /FiO₂ ] ratio, oxygen saturation [SaO₂ ], base excess, and bicarbonate [HCO₃ ]).

RESULTS

In the pRBC units, the PCV increased from 70% to 78.33%, the lactate concentration increased 627%, the potassium concentration increased 183%, the percent hemolysis reached 0.69%, and the pH decreased 9% after 28 days. However, the dogs who received transfusions were not negatively affected. There was a significant increase in PCVs, and a significant decrease in heart rates.

CONCLUSION

Canine pRBCs undergo hematologic, blood gas, and biochemical alterations during storage; however, the transfusion of pRBCs stored for up to 21 days increased PCVs without causing harm to the dogs.

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

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

Modelling of Red Blood Cell Morphological and Deformability Changes during In-Vitro Storage

Storage lesion is a critical issue facing transfusion treatments, and it adversely affects the quality and viability of stored red blood cells (RBCs). RBC deformability is a key indicator of cell health. Deformability measurements of each RBC unit are a key challenge in transfusion medicine research and clinical haematology. In this paper, a numerical study, inspired from the previous research for RBC deformability and morphology predictions, is conducted for the first time, to investigate the deformability and morphology characteristics of RBCs undergoing storage lesion. This study investigates the evolution of the cell shape factor, elongation index and membrane spicule details, where applicable, of discocyte, echinocyte I, echinocyte II, echinocyte III and sphero-echinocyte morphologies during 42 days of in-vitro storage at 4 °C in saline-adenine-glucose-mannitol (SAGM). Computer simulations were performed to investigate the influence of storage lesion-induced membrane structural defects on cell deformability and its recoverability during optical tweezers stretching deformations. The predicted morphology and deformability indicate decreasing quality and viability of stored RBCs undergoing storage lesion. The loss of membrane structural integrity due to the storage lesion further degrades the cell deformability and recoverability during mechanical deformations. This numerical approach provides a potential framework to study the RBC deformation characteristics under varying pathophysiological conditions for better diagnostics and treatments.

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.

Decoding the metabolic landscape of pathophysiological stress-induced cell death in anucleate red blood cells

BACKGROUND

In response to stress, anucleate red blood cells (RBCs) can undergo a process of atypical cell death characterised by intracellular Ca²⁺ accumulation and phosphatidylserine (PS) externalisation. Here we studied alterations in RBC metabolism, a critical contributor to their capacity to survive environmental challenges, during this process.

MATERIALS AND METHODS

Metabolomics analyses of RBCs and supernatants, using ultra-high-pressure liquid chromatography coupled to mass spectrometry, were performed after in vitro exposure of RBCs to different pathophysiological cell stressors, including starvation, extracellular hypertonicity, hyperthermia, and supraphysiological ionic stress. Cell death was examined by flow cytometry.

RESULTS

Our data show that artificially enhancing RBC cytosolic Ca²⁺ influx significantly enhanced purine oxidation and strongly affected cellular bioenergetics by reducing glycolysis. Depleting extracellular Ca²⁺ curtailed starvation-induced cell death, an effect paralleled by the activation of compensatory pathways such as the pentose phosphate pathway, carboxylic acid metabolism, increased pyruvate to lactate ratios (methemoglobin reductase activation), one-carbon metabolism (protein-damage repair) and glutathione synthesis; RBCs exposed to hypertonic shock displayed a similar metabolic profile. Furthermore, cell stress promoted lipid remodelling as reflected by the levels of free fatty acids, acyl-carnitines and CoA precursors. Notably, RBC PS exposure, independently of the stressor, showed significant correlation with the levels of free fatty acids, glutamate, cystine, spermidine, tryptophan, 5-oxoproline, lactate, and hypoxanthine.

DISCUSSION

In conclusion, different cell death-inducing pathophysiological stressors, encountered in various clinical conditions, result in differential RBC metabolic phenotypes, only partly explained by intracellular Ca²⁺ levels and ATP availability.

Contrasting effects of stored allogeneic red blood cells and their supernatants on permeability and inflammatory responses in human pulmonary endothelial cells

Transfusion of red blood cells (RBCs) is a common life-saving clinical practice in severely anemic or hemorrhagic patients; however, it may result in serious pathological complications such as transfusion-related acute lung injury. The factors mediating the deleterious effects of RBC transfusion remain unclear. In this study, we tested the effects of washed long-term (RBC-O; >28 days) versus short-term (RBC-F; <14 days) stored RBCs and their supernatants on lung endothelial (EC) permeability under control and inflammatory conditions. RBCs enhanced basal EC barrier function as evidenced by an increase in transendothelial electrical resistance and decrease in permeability for macromolecules. RBCs also attenuated EC hyperpermeability and suppressed secretion of EC adhesion molecule ICAM-1 and proinflammatory cytokine IL-8 in response to LPS or TNF-α. In both settings, RBC-F had slightly higher barrier protective effects as compared with RBC-O. In contrast, supernatants from both RBC-F and RBC-O disrupted the EC barrier. The early phase of EC permeability response caused by RBC supernatants was partially suppressed by antioxidant N-acetyl cysteine and inhibitor of Src kinase family PP2, while addition of heme blocker and inhibition of NOD-like receptor family pyrin domain containing protein 3 (NLRP3), stress MAP kinases, receptor for advanced glycation end-products (RAGE), or Toll-like receptor-4 (TLR4) signaling were without effect. Morphological analysis revealed that RBC supernatants increased LPS- and TNF-α-induced breakdown of intercellular junctions and formation of paracellular gaps. RBC supernatants augmented LPS- and TNF-α-induced EC inflammation reflected by increased production of IL-6, IL-8, and soluble ICAM-1. These findings demonstrate the deleterious effects of RBC supernatants on EC function, which may have a major impact in pathological consequences associated with RBC transfusion.

A Flow Induced Autoimmune Response and Accelerated Senescence of Red Blood Cells in Cardiovascular Devices

Red blood cells (RBCs) passing through heart pumps, prosthetic heart valves and other cardiovascular devices undergo early senescence attributed to non-physiologic forces. We hypothesized that mechanical trauma accelerates aging by deformation of membrane proteins to cause binding of naturally occurring IgG. RBCs isolated from blood of healthy volunteers were exposed to high shear stress in a viscometer or microfluidics channel to mimic mechanical trauma and then incubated with autologous plasma. Increased binding of IgG was observed indicating forces caused conformational changes in a membrane protein exposing an epitope(s), probably the senescent cell antigen of band 3. The binding of immunoglobulin suggests it plays a role in the premature sequestration and phagocytosis of RBCs in the spleen. Measurement of IgG holds promise as a marker foreshadowing complications in cardiovascular patients and as a means to improve the design of medical devices in which RBCs are susceptible to sublethal trauma.

Single-cell modeling of routine clinical blood tests reveals transient dynamics of human response to blood loss

Low blood count is a fundamental disease state and is often an early sign of illnesses including infection, cancer, and malnutrition, but our understanding of the homeostatic response to blood loss is limited, in part by coarse interpretation of blood measurements. Many common clinical blood tests actually include thousands of single-cell measurements. We present an approach for modeling the unsteady-state population dynamics of the human response to controlled blood loss using these clinical measurements of single-red blood cell (RBC) volume and hemoglobin. We find that the response entails (1) increased production of new RBCs earlier than is currently detectable clinically and (2) a previously unrecognized decreased RBC turnover. Both component responses offset the loss of blood. The model provides a personalized dimensionless ratio that quantifies the balance between increased production and delayed clearance for each individual and may enable earlier detection of both blood loss and the response it elicits.

Packed Red Blood Cell Transfusion Modulates Myeloid Dendritic Cell Activation and Inflammatory Response In Vitro

Transfusion of packed red blood cells (PRBCs) modulates patients' immune responses and clinical outcomes; however, the underpinning mechanism(s) remain unknown. The potential for PRBC to modulate myeloid dendritic cells (mDC) and blood DC antigen 3 was assessed using an in vitro transfusion model. In parallel, to model processes activated by viral or bacterial infection, toll-like receptor agonists polyinosinic:polycytidylic acid or lipopolysaccharide were added. Exposure to PRBC upregulated expression of CD83 and downregulated CD40 and CD80 on both DC subsets, and it suppressed production of interleukin (IL)-6, IL-8, IL-12, tumor necrosis factor-α, and interferon-gamma-inducible protein-10 by these cells. Similar effects were observed when modeling processes activated by concurrent infection. Furthermore, exposure to PRBC at date of expiry was associated with more pronounced effects in all assays. Our study suggests PRBC have an impact on recipient DC function, which may result in failure to establish an appropriate immune response, particularly in patients with underlying infection.

Age-Related Modulations in Erythrocytes under Blood Bank Conditions

Background

During storage of erythrocytes, storage lesions are formed that reduce the safety and efficacy of the stored blood. Thus, there is a need to understand the changes that occur during storage. Most studies have focused on storage of a mixed population of erythrocytes. The aim of this study is to analyze the changes in young and old erythrocytes over the course if storage.

Materials and Methods

Blood was collected from the blood bank at the Kempegowda Institute of Medical Sciences (KIMS) Hospital (Bengaluru, India) and stored for 35 days in CPDA-1 at 4°C. Every 5 days, erythrocytes were separated based on the blood's age using a Percoll-BSA gradient. Young and old erythrocytes obtained were used for analysis of the following oxidative stress (OS) markers: hemoglobin (Hb), hemolysis, mechanical fragility, antioxidant enzymes (superoxide dismutase and catalase [CAT]), superoxides, sialic acid, glutamic oxaloacetate transaminase (GOT), glucose, plasma membrane redox system (PMRS), total antioxidant capacity-cupric ion reducing antioxidant capacity assay (TAC_CUPRAC), lactate dehydrogenase (LDH), lipid peroxidation products (malondialdehyde [MDA] and conjugate dienes), and protein oxidation products (advanced oxidation protein products and protein sulfhydryls).

Result

Young cells had higher amounts of Hb, sialic acid, GOT, LDH, TAC_CUPRAC, CAT, and superoxides compared to old cells. Old cells, however, had higher PMRS and MDA levels with respect to young cells.

Discussion

Young cells could endure OS during storage more efficiently than old cells. In conclusion, the efficacy of stored blood depends on the ratio of young cells in the population. This study highlights the prospects of storing young erythrocytes for a prolonged shelf life of blood.

Red Blood Cell Homeostasis and Altered Vesicle Formation in Patients With Paroxysmal Nocturnal Hemoglobinuria

A subset of the red blood cells (RBCs) of patients with paroxysmal nocturnal hemoglobinuria (PNH) lacks GPI-anchored proteins. Some of these proteins, such as CD59, inhibit complement activation and protect against complement-mediated lysis. This pathology thus provides the possibility to explore the involvement of complement in red blood cell homeostasis and the role of GPI-anchored proteins in the generation of microvesicles (MVs) in vivo. Detailed analysis of morphology, volume, and density of red blood cells with various CD59 expression levels from patients with PNH did not provide indications for a major aberration of the red blood cell aging process in patients with PNH. However, our data indicate that the absence of GPI-anchored membrane proteins affects the composition of red blood cell-derived microvesicles, as well as the composition and concentration of platelet-derived vesicles. These data open the way toward a better understanding on the pathophysiological mechanism of PNH and thereby to the development of new treatment strategies.

Alterations in phospholipid profiles of erythrocytes deep-frozen without cryoprotectants

The erythrocyte membrane is composed of a phospholipid bilayer, which is known to undergo physicochemical changes during storage at low temperatures. This study was conducted to identify marker phospholipids that indicate alteration during deep-frozen storage and to determine the amount of marker phospholipids. Our research suggested a method to detect phospholipids by profiling analysis of thermally injured red blood cells (RBCs) without protecting agents. Human blood was stored at -80°C for 72 days. The RBC membrane phospholipids were extracted through a modified Bligh and Dyer method. Six selected phospholipids were analyzed and quantified using liquid chromatography-tandem mass spectrometry, and an in vitro model system was developed. The intracellular level of N-nervonoyl-D-erythro-sphingosylphosphorylcholine significantly increased in the thermally injured RBCs, and multiple biomarker candidates were evaluated by profiling analysis and mass spectrometry technology for targeted metabolomics.

Preclinical Evaluation of Safety and Biodistribution of Red Cell Microparticles: A Novel Hemostatic Agent

BACKGROUND

Uncontrollable bleeding is a major cause of mortality and morbidity worldwide. Effective hemostatic agents are urgently needed. Red cell microparticles (RMPs) are a highly promising hemostatic agent. This study evaluated the safety profile of RMPs preliminary to clinical trial.

METHODS AND RESULTS

RMPs were prepared from type O+ human red blood cell by high-pressure extrusion. Male rats were treated with RMPs either a 1 × bolus, or 4 × or 20 × administered over 60 minutes. The vehicle-treated group was used as a control. Effects on physiological parameters were evaluated; namely, blood pressure, body and head temperature, hematocrit, and blood gases. We did not observe any adverse effects of RMPs on these physiological parameters. In addition, brain, heart, and lungs of rats treated with 4 × dose (bolus followed by infusion over 60 minutes) or vehicle were examined histologically for signs of thrombosis or other indications of toxicity. No thrombosis or indications of toxicity in brain, heart, or lungs were observed. Studies revealed that RMPs were distributed mainly in liver, spleen, and lymph nodes, and were potentially excreted through the kidneys.

CONCLUSIONS

Our study indicates that RMP administration appears not to have any negative impact on the parameters studied and did not produce thrombosis in heart, brain, and lungs. However, more detailed long-term studies confirming the safety of RMP as a hemostatic agent are warranted.

Whole Blood Storage in CPDA1 Blood Bags Alters Erythrocyte Membrane Proteome

Autologous blood transfusion (ABT) has been frequently abused in endurance sport and is prohibited since the mid-1980s by the International Olympic Committee. Apart from any significant performance-enhancing effects, the ABT may pose a serious health issue due to aging erythrocyte-derived "red cell storage lesions." The current study investigated the effect of blood storage in citrate phosphate dextrose adenine (CPDA1) on the red blood cell (RBC) membrane proteome. One unit of blood was collected in CPDA1 blood bags from 6 healthy female volunteers. RBC membrane protein samples were prepared on days 0, 14, and 35 of storage. Proteins were digested in gel and peptides separated by nanoliquid chromatography coupled to tandem mass spectrometry resulting in the confident identification of 33 proteins that quantitatively change during storage. Comparative proteomics suggested storage-induced translocation of cytoplasmic proteins to the membrane while redox proteomics analysis identified 14 proteins prone to storage-induced oxidation. The affected proteins are implicated in the RBC energy metabolism and membrane vesiculation and could contribute to the adverse posttransfusion outcomes. Spectrin alpha chain, band 3 protein, glyceraldehyde-3-phosphate dehydrogenase, and ankyrin-1 were the main proteins affected by storage. Although potential biomarkers of stored RBCs were identified, the stability and lifetime of these markers posttransfusion remain unknown. In summary, the study demonstrated the importance of studying storage-induced alterations in the erythrocyte membrane proteome and the need to understand the clearance kinetics of transfused erythrocytes and identified protein markers.

Evolution of intramural duodenal hematomas on magnetic resonance imaging

BACKGROUND

The magnetic resonance imaging (MRI) characteristics of evolving duodenal hematomas in children are unknown.

OBJECTIVE

To describe the MRI changes exhibited by evolving duodenal hematomas and the likely mechanisms behind these changes.

MATERIALS AND METHODS

We retrospectively reviewed the MR features of intramural duodenal hematomas (6 lesions, 10 examinations) studied on a 1.5-T MR unit. All patients had clinical histories of blunt abdominal trauma or endoscopic procedures and we were able to determine the time interval between the onset and MR imaging. We evaluated and analyzed the appearance and signal intensity patterns of hematomas of varying ages and we compared the results with those in previously reported intracranial hematomas.

RESULTS

The imaging appearances on five examinations were consistent with presence of deoxyhemoglobin. Two of these lesions were hypointense on T2-weighted images and iso- to hyperintense on T1-weighted images. Three had heterogeneous appearances on both T1- and T2-weighted images, and the bulk of the hematoma progressively increased in size and signal intensity on T2-weighted images. On the remaining five examinations, one lesion was hyperintense on T1-weighted images and iso- to hyperintense on T2-weighted images, consistent with intracellular methemoglobin, and four lesions were hyperintense on both T1- and T2-weighted images, consistent with the presence of extracellular methemoglobin. Duodenal hematoma stages were slower than those of intracranial hematomas; the acute stage spanned 2-7 days, and early and late subacute stages occurred 10-17 days after the injury.

CONCLUSION

Duodenal hematomas evolve like intracranial hematomas, but slower. Signal heterogeneity is common in the acute stage.

Quantification of stored red blood cell fluctuations by time-lapse holographic cell imaging

We propose methods to quantitatively calculate the fluctuation rate of red blood cells with nanometric axial and millisecond temporal sensitivity at the single-cell level by using time-lapse holographic cell imaging. For this quantitative analysis, cell membrane fluctuations (CMFs) were measured for RBCs stored at different storage times. Measurements were taken over the whole membrane for both the ring and dimple sections separately. The measurements show that healthy RBCs that maintain their discocyte shape become stiffer with storage time. The correlation analysis demonstrates a significant negative correlation between CMFs and the sphericity coefficient, which characterizes the morphological type of erythrocyte. In addition, we show the correlation results between CMFs and other morphological properties such as projected surface area, surface area, mean corpuscular volume, and mean corpuscular hemoglobin.

A microfluidic approach to study the effect of mechanical stress on erythrocytes in sickle cell disease

The human red blood cell is a biconcave disc of 6-8 × 2 μm that is highly elastic. This capacity to deform enables it to stretch while circulating through narrow capillaries to ensure its main function of gas exchange. Red cell shape and deformability are altered in membrane disorders because of defects in skeletal or membrane proteins affecting protein-protein interactions. Red cell properties are also altered in other pathologies such as sickle cell disease. Sickle cell disease is a genetic hereditary disorder caused by a single point mutation in the β-globin gene generating sickle haemoglobin (HbS). Hypoxia drives HbS polymerisation that is responsible for red cell sickling and reduced deformability. The main clinical features of sickle cell disease are vaso-occlusive crises and haemolytic anaemia. Foetal haemoglobin (HbF) inhibits HbS polymerisation and positively impacts red cell survival in the circulation but the mechanism through which it exerts this action is not fully characterized. In this study, we designed a microfluidic biochip mimicking the dimensions of human capillaries to measure the impact of repeated mechanical stress on the survival of red cells at the single cell scale under controlled pressure. We show that mechanical stress is a critical parameter underlying intravascular haemolysis in sickle cell disease and that high intracellular levels of HbF protect against lysis. The biochip is a promising tool to address red cell deformability in pathological situations and to screen for molecules positively impacting this parameter in order to improve red cell survival in the circulation.

Identification of Oxidative Stress in Red Blood Cells with Nanoscale Chemical Resolution by Infrared Nanospectroscopy

During their lifespan, Red blood cells (RBC), due to their inability to self-replicate, undergo an ageing degradation phenomenon. This pathway, both in vitro and in vivo, consists of a series of chemical and morphological modifications, which include deviation from the biconcave cellular shape, oxidative stress, membrane peroxidation, lipid content decrease and uncoupling of the membrane-skeleton from the lipid bilayer. Here, we use the capabilities of atomic force microscopy based infrared nanospectroscopy (AFM-IR) to study and correlate, with nanoscale resolution, the morphological and chemical modifications that occur during the natural degradation of RBCs at the subcellular level. By using the tip of an AFM to detect the photothermal expansion of RBCs, it is possible to obtain nearly two orders of magnitude higher spatial resolution IR spectra, and absorbance images than can be obtained on diffraction-limited commercial Fourier-transform Infrared (FT-IR) microscopes. Using this approach, we demonstrate that we can identify localized sites of oxidative stress and membrane peroxidation on individual RBC, before the occurrence of neat morphological changes in the cellular shape.

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.