Fever-range hyperthermia (38–41 °C) is a typical physiological response to infection, inflammation, and systemic stress. Although increased temperatures are known to affect blood rheology and erythrocyte activity, their comprehensive impact on red blood cell (RBC) structure, mechanics, and lifespan remains incompletely understood. This review summarizes current understanding of how moderate hyperthermia affects RBC membrane structure, internal behavior, mechanical properties, and clearance cues. Evidence shows that brief exposure to febrile temperatures primarily induces reversible biophysical modifications, including heightened membrane fluidity, increased membrane fluctuations, changes in hemoglobin–water interactions, and short-term improvements in deformability. These changes reflect adaptive adjustments within the membrane–cytosol–cytoskeleton system, potentially temporarily boosting microcirculatory flow. On the other hand, prolonged or repeated heat stress causes oxidative damage, hemoglobin auto-oxidation, accumulation of membrane-bound hemoglobin, band 3 clustering, cytoskeletal restructuring, calcium imbalance, and disruption of membrane lipid asymmetry. These effects weaken membrane stability and lead to vesiculation, shape changes, increased cell fragility, altered aggregation, enhanced adhesion, and activation of clearance mechanisms. A primary focus is the transition from reversible membrane softening to permanent structural damage over time. The research supports a model in which temperature affects RBC mechanics and related membrane, cytosolic, and signaling processes that influence RBC viability. We propose interpreting febrile hyperthermia as a dynamic factor that shifts RBCs from an adaptive phase to accelerated aging and removal during prolonged heat exposure. This perspective enhances our understanding of RBC behavior during fever and systemic inflammation and underscores the role of temperature in shaping erythrocyte function and lifespan.

Polymeric micro- and nanoplastic particles (MPs/NPs) have recently been recognized as potential biomedical pollutants that can enter the human bloodstream. Advances in analytical techniques have detected various polymers in human blood, raising concerns about their possible interactions with circulating cells, especially red blood cells (RBCs). RBCs are abundant, highly flexible, and lack internal repair mechanisms. This review summarizes current knowledge of how MPs and NPs interact with RBCs, emphasizing how physicochemical factors, including particle size, surface chemistry, environmental aging, and protein corona formation, influence hemocompatibility. Studies indicate that MPs can bind to RBC membranes, change the ζ-potential, reduce deformability, induce vesiculation and eryptosis, and, in some cases, cause hemolysis. These sublethal and lethal effects could have clinical significance, as even minor impairments in RBC mechanics may affect microvascular blood flow, oxygen delivery, and splenic clearance. Vulnerable populations—such as neonates and transfusion recipients—may be particularly susceptible to microparticle-induced RBC stress. While experimental data suggest MPs can harm RBCs, significant uncertainties remain regarding actual exposure levels, in vivo toxicity, and long-term health consequences. Addressing these gaps will require a multidisciplinary approach that combines environmental science, membrane biophysics, analytical chemistry, and clinical hematology to evaluate the health risks associated with increased microplastic exposure.

Blood units are routinely collected from adult donors and stored as packed red blood cells (PRBC). The quality of PRBC, including their deformability, decreases during storage. Since PRBC transfusion has been reported to promote circulatory issues in premature neonates (PNs), they typically receive freshly stored units. To test the hypothesis that freshly stored PRBCs can provide red blood cells (RBCs) with appropriate deformability for PN recipients, we compared the deformability of PRBCs transfused to PNs with that of cord blood RBCs (CRBCs), which are known to have deformability equivalent to that of newborn RBCs (PN-RBC). We found that, on average, CRBC deformability was higher than that of PRBCs. However, both showed significant variability with overlapping ranges. A highly significant correlation was observed between cell deformability and the combined levels of specific membrane proteins (ezrin, stomatin, flotillins) and membrane-bound hemoglobin (Pearson coefficient > 0.70, p < 0.02). This study indicates that the storage duration is inadequate for selecting PRBCs for PN recipients. PRBCs with deformability similar to that of PN-RBCs could enable safer and more effective transfusions for PN patients. Measuring membrane proteins alongside membrane-bound hemoglobin can serve as a useful method for selecting appropriate PRBC units for transfusion to PNs.

The mechanical stability and deformability of erythrocytes are vital for their function as they traverse capillaries, where shear stress can reach up to 10 Pa under physiological conditions. Human serum albumin (HSA) is known to help maintain erythrocyte stability by influencing cell shape, membrane integrity, and resistance to hemolysis. However, the precise mechanisms by which albumin exerts these effects remain debated, with some studies indicating a stabilizing role and others suggesting the opposite. This review highlights that under high shear rates, albumin molecules may undergo unfolding due to normal stress differences. Such structural changes can significantly alter albumin’s interactions with the erythrocyte membrane, thereby affecting cell mechanical stability. We discuss two potential scenarios explaining how albumin influences erythrocyte mechanics under shear stress, considering both the viscoelastic properties of blood and those of the erythrocyte membrane. Based on theoretical analyses and experimental evidence from the literature, we propose that albumin’s effect on erythrocyte mechanical stability depends on (i) the transition between unfolded and folded states of the protein and (ii) the impact of shear stress on the erythrocyte membrane’s ζ-potential. Understanding these factors is essential for elucidating the complex relationship between albumin and erythrocyte mechanics in physiological and pathological conditions.

Water molecules in the cytosol of red blood cells (RBCs) may exist in a free or bound state. The ratio between the free and bound water depends on the composition of the cytoplasm, particularly on the hemoglobin concentration. Microwave dielectric spectroscopy (MDS) provides information on the state of intracellular water in red blood cell suspension and the erythrocyte cytosol state. In the presented study, we used MDS to assess the differences in the free-to-bound water ratio in subpopulations of freshly donated human erythrocytes of different ages (young, mature, and senescent cells) obtained by fractionation in a Percoll density gradient. The obtained MDS parameters (dielectric strength ∆ε, the relaxation time τ, and the broadening parameter α) were compared with the red blood cell indices and single cell deformability measurements obtained for each subpopulation. We demonstrated that the unique hematological indices and deformability of red blood cells of different ages are well-correlated with the specific values of dielectric fitting parameters. The obtained results indicate that the dielectric properties of cytosolic water can serve as a sensitive marker of changes occurring in the cytosol of red blood cells during cell aging.

Human red blood cells (RBCs) are highly differentiated cells, essential in almost all physiological processes. During their circulation in the bloodstream, RBCs are exposed to varying levels of shear stress ranging from 0.1–10 Pa under physiological conditions to 50 Pa in arterial stenotic lesions. Moreover, the flow of blood through splenic red pulp and through artificial organs is associated with brief exposure to even higher levels of shear stress, reaching up to hundreds of Pa. As a result of this exposure, some properties of the cytosol, the cytoskeleton, and the cell membrane may be significantly affected. In this review, we aim to systematize the available information on RBC response to shear stress by focusing on reported changes in various red cell properties. We pay special attention to the results obtained using microfluidics, since these devices allow the researcher to accurately simulate blood flow conditions in the capillaries and spleen.

Hemoglobin A1C (HbA1C), a non-enzymatically glycated form of adult hemoglobin (HbA0), is a widely used biomarker for diabetes. Its concentration is strongly correlated with the long-term glycemic state and the risk of diabetes development. However, beyond its diagnostic role, its physiological functions remain poorly understood. To fill this gap, we investigated the intracellular distribution of HbA1C and its potential impact on red blood cell (RBC) functions. Specifically, the differences in cytosolic and membrane pools of HbA1C in RBCs from individuals with prediabetes, overt type 2 diabetes (T2D), and healthy controls were explored. Our cross-sectional findings confirmed the intracellular heterogeneity of HbA1C and revealed a strong correlation between fluctuations in HbA1C and those of other hemoglobin isoforms, specifically HbA2 and HbA0. This correlation was particularly evident in the context of diabetes or acute exposure to Ca2+-depleted environments. We also observed that short-term hyperglycemia does not significantly alter HbA1C intracellular localization. Furthermore, we found that the intracellular distribution of HbA1C is correlated with several physiological properties of RBCs, with these links varying according to the specific pathological abnormalities associated with pre- and overt diabetes. Further research is required to fully understand the mechanisms and implications of these observations.

The deformability of red blood cells (RBCs), expressing their ability to change their shape as a function of flow-induced shear stress, allows them to optimize oxygen delivery to the tissues and minimize their resistance to flow, especially in microcirculation. During physiological aging and blood storage, or under external stimulations, RBCs undergo metabolic and structural alterations, one of which is hemoglobin (Hb) redistribution between the cytosol and the membrane. Consequently, part of the Hb may attach to the cell membrane, and although this process is reversible, the increase in membrane-bound Hb (MBHb) can affect the cell’s mechanical properties and deformability in particular. In the present study, we examined the correlation between the MBHb levels, determined by mass spectroscopy, and the cell deformability, determined by image analysis. Six hemoglobin subunits were found attached to the RBC membranes. The cell deformability was negatively correlated with the level of four subunits, with a highly significant inter-correlation between them. These data suggest that the decrease in RBC deformability results from Hb redistribution between the cytosol and the cell membrane and the respective Hb interaction with the cell membrane.

Aging-related processes lead to significant metabolic and structural changes in red blood cells (RBCs) and, as a result, to heterogeneity in cell populations. Using the Percoll linear density gradient, separating the RBC population and obtaining fractions enriched with cells of different ages is possible. Previously, cells from the “light” fraction were characterized by increased deformability. However, the distribution of RBC deformability in subpopulations possessing a different density has not been studied. In this study, we measured the deformability of RBCs from cell fractions characterized by different densities. RBC deformability was determined using a computerized cell flow-properties analyzer, which provides the deformability distribution in a population of 10,000–15,000 cells. Our results demonstrate a strong correlation between the cytosol hemoglobin concentration and the cell deformation indexes. In addition, we show that the “lightest” fraction of RBCs contains the lowest number of deformable and the highest number of highly deformable cells. In contrast, the “dense” fraction is enriched with undeformable RBCs, with a minimal presence of highly deformable cells. In summary, we have shown that RBC fractions depleted or enriched with undeformable cells can be obtained by using a density gradient. However, these fractions are not homogeneous in their deformability properties.

The sensitivity of cytosol water's microwave dielectric (MD) response to D-glucose uptake in Red Blood Cells (RBCs) allows the detailed study of cellular mechanisms as a function of controlled exposures to glucose and other related analytes like electrolytes. However, the underlying mechanism behind the sensitivity to glucose exposure remains a topic of debate. In this research, we utilize MDS within the frequency range of 0.5-40 GHz to explore how ionic redistributions within the cell impact the microwave dielectric characteristics associated with D-glucose uptake in RBC suspensions. Specifically, we compare glucose uptake in RBCs exposed to the physiological concentration of Ca2+ vs. Ca-free conditions. We also investigate the potential involvement of Na+/K+ redistribution in glucose-mediated dielectric response by studying RBCs treated with a specific Na+/K+ pump inhibitor, ouabain. We present some insights into the MD response of cytosol water when exposed to Ca2+ in the absence of D-glucose. The findings from this study confirm that ion-induced alterations in bound/bulk water balance do not affect the MD response of cytosol water during glucose uptake.

The membrane-bound hemoglobin (Hb) fraction impacts red blood cell (RBC) rheology and metabolism. Therefore, Hb-RBC membrane interactions are precisely controlled. For instance, the signaling function of membrane-bound deoxy-Hb and the structure of the docking sites in the cytosolic domain of the anion exchanger 1 (AE-1) protein are well documented; however, much less is known about the interaction of Hb variants with the erythrocyte's membrane. Here, we identified factors other than O2 availability that control Hb abundance in the membrane-bound fraction and the possible variant-specific binding selectivity of Hb to the membrane. We show that depletion of extracellular Ca2+ by chelators, or its omission from the extracellular medium, leads to membrane-bound Hb release into the cytosol. The removal of extracellular Ca2+ further triggers the redistribution of HbA0 and HbA2 variants between the membrane and the cytosol in favor of membrane-bound HbA2. Both effects are reversible and are no longer observed upon reintroduction of Ca2+ into the extracellular medium. Fluctuations of cytosolic Ca2+ also impact the pre-membrane Hb pool, resulting in the massive transfer of Hb to the cellular cytosol. We hypothesize that AE-1 is the specific membrane target and discuss the physiological outcomes and possible clinical implications of the Ca2+ regulation of the intracellular Hb distribution.

Red blood cell (RBC) deformability, expressing their ability to change their shape, allows them to minimize their resistance to flow and optimize oxygen delivery to the tissues. RBC with reduced deformability may lead to increased vascular resistance, capillary occlusion, and impaired perfusion and oxygen delivery. A reduction in deformability, as occurs during RBC physiological aging and under blood storage, is implicated in the pathophysiology of diverse conditions with circulatory disorders and anemias. The change in RBC deformability is associated with metabolic and structural alterations, mostly uncharacterized. To bridge this gap, we analyzed the membrane protein levels, using mass spectroscopy, of RBC with varying deformability determined by image analysis. In total, 752 membrane proteins were identified. However, deformability was positively correlated with the level of only fourteen proteins, with a highly significant inter-correlation between them. These proteins are involved in membrane rafting and/or the membrane–cytoskeleton linkage. These findings suggest that the reduction of deformability is a programmed (not arbitrary) process of remodeling and shedding of membrane fragments, possibly mirroring the formation of extracellular vesicles. The highly significant inter-correlation between the deformability-expressing proteins infers that the cell deformability can be assessed by determining the level of a few, possibly one, of them.

In this article, we discuss the dielectric relaxation of water in the hemoglobin (Hb) aqueous solutions in different states [methemoglobin (MetHb), oxygenated hemoglobin (OxyHb), and deoxygenated hemoglobin (DeoxyHb)]. The interpretation of the results was performed by the 3-D trajectory approach, which considers dielectric parameters of water relaxation and protein concentration. It has been shown that the interaction of amino acid dipole residues, located on the surface of a protein macromolecule, with water dipoles determines the protein hydration. In addition, ions of the buffer, in which proteins are dissolved, are also hydrated. The transition from a dipole–ion interaction of water molecules to a dipole–dipole interaction of water with an increase in protein concentration is observed. We proposed a new approach to calculate Hb hydration shells. The theoretical model defines the change in the ratio between the content of free and bound water molecules (BWMs) as a function of MetHb concentration in ion-free and ion-containing aqueous solutions. It considers the number of positive and negative charges at the surface of the protein molecule, the number of BWMs in its hydration shells, and the partition of water molecules bound to MetHb and the inorganic ions. The theoretical evaluation of the ratio of free-to-bound water reveals that, in the absence of ions, MetHb binds about 1400 water molecules, which is in good agreement with experimental data. At MetHb concentrations close to physiological, Hb is dominating in binding water over the inorganic ions, and the amount of BWM remains at the level of ~20% of total cytosol water as the concentration of Hb increases above 15 g/dL. These results suggest that in the physiological concentration diapason (29–35 g/dL), molecules of MetHb are so close together that their hydration shells interact and shrink from four to one layer of water molecules. In contrast, Hb molecules aggregate to neutralize their surface charges mutually.

Red blood cells (RBCs, erythrocytes) are highly specialized cells devoted to the transport of respiratory gases [...].

Aim About 50% of premature neonates (PN) are treated with transfusion of packed red blood cells (PRBC) collected from adult donors, which has been suggested to potentially provoke PN pathologies, characterized as blood circulation disorders. RBC have properties that are key determinants of blood circulation, primarily the cell deformability. In previous studies we have shown that transfusion of RBC with reduced deformability impaired the transfusion outcome. Although RBC of PN (PN-RBC) are larger, and their microvessels are narrower than those of adults, their blood circulation is very efficient, pointing to the possibility that the deformability of adults' PRBC is inferior to that of PN-RBC, and that treating PN with PRBC transfusion might, therefore, introduce a risk to the recipients. This would infer that PN should be given RBC with high deformability. However, since using PN-RBC is not feasible, the use of cord blood RBC (CB-RBC) is a sound alternative, assuming that the deformability of CB-RBC is comparable to that of PN-RBC.The present study is aimed at testing this hypothesis. Methods We compared the deformability of (1) RBC of PN vs. the PRBC they received, and (2) PN-RBC vs. their autologous CB-RBC. Results 1. The deformability of the transfused PRBC is indeed inferior to that of PN-RBC. 2. The deformability of CB-RBC is equivalent to that of PN-RBC. Conclusion This study supports the notion that treating PN with transfusion of adults' PRBC has the potential to introduce a circulatory risk to the recipients, while CB-RBC, with their superior deformability, provides a safer and more effective PN-specific transfusion therapy.

TransfusionVolume 62, Issue 6 p. 1310-1311 LETTER Plasma transfusion to premature newborns as a risk factor of necrotizing enterocolitis development: Proposed mechanism Dan Arbell, Dan Arbell Department of Pediatric Surgery, Hadassah University Hospital, Jerusalem, IsraelSearch for more papers by this authorGregory Barshtein, Corresponding Author Gregory Barshtein [email protected] orcid.org/0000-0001-6588-7229 Department of Biochemistry, Hebrew University Faculty of Medicine, Jerusalem, Israel Correspondence Gregory Barshtein, Department of Biochemistry Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel. Email: [email protected]Search for more papers by this authorAlexander Gural, Alexander Gural Blood Bank, Hadassah University Hospital, Jerusalem, IsraelSearch for more papers by this authorSmadar Eventov-Friedman, Smadar Eventov-Friedman Department of Neonatology, Hadassah University Hospital, Jerusalem, IsraelSearch for more papers by this authorSaul Yedgar, Saul Yedgar orcid.org/0000-0001-7676-9017 Department of Biochemistry, Hebrew University Faculty of Medicine, Jerusalem, IsraelSearch for more papers by this author Dan Arbell, Dan Arbell Department of Pediatric Surgery, Hadassah University Hospital, Jerusalem, IsraelSearch for more papers by this authorGregory Barshtein, Corresponding Author Gregory Barshtein [email protected] orcid.org/0000-0001-6588-7229 Department of Biochemistry, Hebrew University Faculty of Medicine, Jerusalem, Israel Correspondence Gregory Barshtein, Department of Biochemistry Hebrew University-Hadassah Medical School, Jerusalem, 91120, Israel. Email: [email protected]Search for more papers by this authorAlexander Gural, Alexander Gural Blood Bank, Hadassah University Hospital, Jerusalem, IsraelSearch for more papers by this authorSmadar Eventov-Friedman, Smadar Eventov-Friedman Department of Neonatology, Hadassah University Hospital, Jerusalem, IsraelSearch for more papers by this authorSaul Yedgar, Saul Yedgar orcid.org/0000-0001-7676-9017 Department of Biochemistry, Hebrew University Faculty of Medicine, Jerusalem, IsraelSearch for more papers by this author First published: 09 June 2022 https://doi.org/10.1111/trf.16876Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. REFERENCES 1Parvizian MK, Barty R, Heddle NM, Li N, McDougall T, Mukerji A, et al. Necrotizing enterocolitis and mortality after transfusion of ABO non-identical blood. Transfusion. 2021; 61: 3094–103. 2Boral LI, Staubach ZG, de Leeuw R, Macivor DC, Kryscio R, Bada HS. Comparison of outcomes of group O vs non-group O premature neonates receiving group O RBC transfusions. Am J Clin Pathol. 2013; 140: 780–6. 3Ben-Ami R, Barshtein G, Mardi T, Deutch V, Elkayam O, Yedgar S, et al. A synergistic effect of albumin and fibrinogen on immunoglobulin-induced red blood cell aggregation. Am J Physiol Heart Circ Physiol. 2003; 285: H2663–9. 4Linderkamp O, Versmold HT, Riegel KP, Betke K. Contributions of red cells and plasma to blood viscosity in preterm and full-term infants and adults. Pediatrics. 1984; 74: 45–51. 5Arbell D, Orkin B, Bar-Oz B, Barshtein G, Yedgar S. Premature red blood cells have decreased aggregation and enhanced aggregability. J Physiol Sci. 2008; 58: 161–5. Volume62, Issue6June 2022Pages 1310-1311 ReferencesRelatedInformation

The potential use of nanomaterials in medicine offers opportunities for novel therapeutic approaches to treating complex disorders. For that reason, a new branch of science, named nanotoxicology, which aims to study the dangerous effects of nanomaterials on human health and on the environment, has recently emerged. However, the toxicity and risk associated with nanomaterials are unclear or not completely understood. The development of an adequate experimental strategy for assessing the toxicity of nanomaterials may include a rapid/express method that will reliably, quickly, and cheaply make an initial assessment. One possibility is the characterization of the hemocompatibility of nanomaterials, which includes their hemolytic activity as a marker. In this review, we consider various factors affecting the hemolytic activity of nanomaterials and draw the reader's attention to the fact that the formation of a protein corona around a nanoparticle can significantly change its interaction with the red cell. This leads us to suggest that the nanomaterial hemolytic activity in the buffer does not reflect the situation in the blood plasma. As a recommendation, we propose studying the hemocompatibility of nanomaterials under more physiologically relevant conditions, in the presence of plasma proteins in the medium and under mechanical stress.

The use of intra-operative blood salvage, dialysis, and artificial organs are associated with the application of non-physiological mechanical stress on red blood cells (RBCs). To explore the effect of these procedures on red cell deformability, we determined it before and after the mechanical stress application both in an in vitro system and following a blood-saving procedure. RBC from eight healthy donors and fifteen packed RBC units were subjected to mechanical stress. RBCs from five patients undergoing orthopedic surgery were also collected. We measured the percent of undeformable cells (%UDFC) in the red cell samples using our cell flow properties image analyzer, which provides the distribution of RBC deformability in a large cell population. Mechanical stress systematically reduced the cell deformability and increased the %UDFC, while simultaneously causing hemolysis of rigid, undeformable RBCs. Ultimately, the overall result depended on the initial level of the undeformable cells; the stress-induced change in the proportion of rigid cells (Δ%UDFC) increased (Δ%UDFC > 0) when its initial value was low, and decreased (Δ%UDFC < 0) when its initial value was high. This suggests that the final impact of mechanical stress on the percent of rigid cells in the RBC population is primarily determined by their initial concentration in the sample.

Dielectric spectroscopy has been used in the study and development of non-invasive glucose monitoring (NIGM) sensors, including the range of microwave frequencies. Dielectric relaxation of red blood cell (RBC) cytosolic water in the microwave frequency band has been shown to be sensitive to variations in the glucose concentration of RBC suspensions. It has been hypothesized that this sensitivity stems from the utilization of D-glucose by RBCs. To verify this proposition, RBCs were pretreated with inhibitors of D-glucose uptake (cytochalasin B and forskolin). Then their suspensions were exposed to different D-glucose concentrations as measured by microwave dielectric spectroscopy (MDS) in the 500 MHz–40 GHz frequency band. After incubation of RBCs with either inhibitor, the dielectric response of water in the cytoplasm, and specifically its relaxation time, demonstrated minimal sensitivity to the change of D-glucose concentration in the medium. This result allows us to conclude that the sensitivity of MDS to glucose uptake is associated with variations in the balance of bulk and bound RBC cytosolic water due to intracellular D-glucose metabolism, verifying the correctness of the initial hypothesis. These findings represent a further argument to establish the dielectric response of water as a marker of glucose variation in RBCs.