Non-Aqueous Polyhedral Liquid Marbles Stabilized with Polymer Plates Having Surface Roughness.

Hydrophobic polymer plates with smooth and rough surfaces are used as a stabilizer for cubic liquid marbles (LMs) to study the effect of surface roughness on their formation. The smooth and rough polymer plates can stabilize LMs using liquids with surface tensions of 72.8-26.6 and 72.8-22.9 mN m-1, respectively. It is clarified that the higher the surface roughness, the lower the surface tension of the liquids are stabilized to form the LMs. These results indicated that the introduction of surface roughness improves the hydrophobicity of the polymer plates and the rough polymer plates can stabilize LMs using liquids with a wider surface tension range. Electron microscopy studies and numerical analyses confirmed that the LMs can be formed, when the Cassie-Baxter wetting state, where θY>90° (θY: the contact angle on smooth surfaces) and θR>90° (θR: the contact angle on rough surfaces), and the metastable Cassie-Baxter wetting state, where θY<90° and θR>90°, are realized. Finally, the synthesis of cubic polymer particles are succeeded by free radical polymerization of the cubic LMs containing a hydrophobic vinyl monomer (dodecyl acrylate) in a solvent-free manner.

Hypoxic storage of donor red cells preserves deformability after exposure to plasma from adults with sickle cell disease.

BACKGROUND: Red cell (RBC) transfusions are beneficial for patients with sickle cell disease (SCD), but ex vivo studies suggest that inflamed plasma from patients with SCD during crises may damage these RBCs, diminishing their potential efficacy. The hypoxic storage of RBCs may improve transfusion efficacy by minimizing the storage lesion. We tested the hypotheses that (1) The donor RBCs exposed to the plasma of patients in crisis would have lower deformability and higher hemolysis than those exposed to non-crisis plasma, and (2) hypoxic storage, compared to standard storage, of donor RBCs could preserve deformability and reduce hemolysis. STUDY DESIGN AND METHODS: 18 SCD plasma samples from patients who had severe acute-phase symptoms (A-plasma; n = 9) or were at a steady-state (S = plasma; n = 9) were incubated with 16 RBC samples from eight units that were stored either under conventional(CRBC) or hypoxic(HRBC) conditions. Hemolysis and microcapillary deformability assays of these RBCs were analyzed using linear mixed-effect models after each sample was incubated in patient plasma overnight at 37°C RESULTS: Relative deformability was 0.036 higher (p < 0.0001) in HRBC pairs compared to CRBC pairs regardless of plasma type. Mean donor RBC hemolysis was 0.33% higher after incubation with A-plasma compared to S-plasma either with HRBC or CRBC (p = 0.04). HRBCs incubated with steady-state patient plasma demonstrated the highest deformability and lowest hemolysis. CONCLUSION: Hypoxic storage significantly influenced RBC deformability. Patient condition significantly influenced post-incubation hemolysis. Together, HRBCs in steady-state plasma maximized donor red cell ex vivo function and survival.

Nonspherical Epoxy Resin Polymer Particles Synthesized via Solvent-Free Polyaddition Reactions.

Cubic liquid marbles (LMs) were fabricated by using various epoxy monomers as internal liquids and millimeter-sized polymer plates as stabilizers. Successively, cubic polymer particles were synthesized via solvent-free polyaddition reactions by exposing the cubic LMs to NH3 vapor used as a curing agent. The effect of the solubility parameters (SPs) for the epoxy monomers on the formation of the cubic polymer particles was investigated. As a result, we succeeded in fabricating cubic polymer particles reflecting the shapes of the original LMs by using epoxy monomers with SP values of 23.70-21.66 (MPa)1/2. Furthermore, the shapes of the LMs could be controlled on demand (e.g., pentahedral and rectangular) by control of the number of polymer plates per LM and/or coalescence of the LMs, resulting in fabrication of polymer particles with shapes reflecting those of the LMs.

The oxygen saturation of red blood cell concentrates: The basis for a novel index of red cell oxidative stress.

BACKGROUND: Oxidative stress is a major driving force in the development of storage lesions in red cell concentrates (RCCs). Unlike manufactured pharmaceuticals, differences in component preparation methods and genetic/physiological status of donors result in nonuniform biochemical characteristics of RCCs. Various characteristics of donated blood on oxygen saturation (SO2 ) distribution were investigated, and a model to estimate potential oxidative stress burden of stored RCC at transfusion is proposed. STUDY DESIGN AND METHODS: The oxygen content of freshly prepared RCCs (770) was quantified noninvasively as fractional hemoglobin saturation (SO2 ) with visible reflectance spectrometry. Using separate RCCs and mimicking typical handling of RCCs during routine storage, evolution of SO2 was followed for construction of an empirical model. Based on this model, the oxygen exposure index (OEI) was formulated to estimate the accumulated oxygen exposure burden of RCC at the time of transfusion. RESULTS: The SO2 of RCCs varied widely at donation (mean 43% ± 1.3%; range 20%-93%). Multivariate regression model showed that sex and processing method had small effects on SO2 (R2  = 0.12), indicating that variability was mainly attributed to other individual donor characteristics. Storage simulation model indicated that median SO2 increased gradually over 6 weeks (approx. 1.3 fold), while OEI increased at a faster rate (approx. eight-fold). CONCLUSION: In addition to storage age, the OEI provides a potential new metric to assess the quality of RCCs at the time of transfusion in terms of their oxidative stress. In future studies, a single noninvasive measurement during storage could link OEI to clinical outcomes in transfusion recipients.

Red blood cell metabolism in Rhesus macaques and humans: comparative biology of blood storage.

Macaques are emerging as a critical animal model in transfusion medicine, because of their evolutionary similarity to humans and perceived utility in discovery and translational science. However, little is known about the metabolism of Rhesus macaque red blood cells (RBC) and how this compares to human RBC metabolism under standard blood banking conditions. Metabolomic and lipidomic analyses, and tracing experiments with [1,2,3-13C3]glucose, were performed using fresh and stored RBC (sampled weekly until storage day 42) obtained from Rhesus macaques (n=20) and healthy human volunteers (n=21). These results were further validated with targeted quantification against stable isotope-labeled internal standards. Metabolomic analyses demonstrated inter-species differences in RBC metabolism independent of refrigerated storage. Although similar trends were observed throughout storage for several metabolic pathways, species- and sex-specific differences were also observed. The most notable differences were in glutathione and sulfur metabolites, purine and lipid oxidation metabolites, acylcarnitines, fatty acyl composition of several classes of lipids (including phosphatidylserines), glyoxylate pathway intermediates, and arginine and carboxylic acid metabolites. Species-specific dietary and environmental compounds were also detected. Overall, the results suggest an increased basal and refrigerator-storage-induced propensity for oxidant stress and lipid remodeling in Rhesus macaque RBC cells, as compared to human red cells. The overlap between Rhesus macaque and human RBC metabolic phenotypes suggests the potential utility of a translational model for simple RBC transfusions, although inter-species storage-dependent differences need to be considered when modeling complex disease states, such as transfusion in trauma/hemorrhagic shock models.

Hypoxic storage of red blood cells improves metabolism and post-transfusion recovery.

BACKGROUND: Blood transfusion is a lifesaving intervention for millions of recipients worldwide every year. Storing blood makes this possible but also promotes a series of alterations to the metabolism of the stored erythrocyte. It is unclear whether the metabolic storage lesion is correlated with clinically relevant outcomes and whether strategies aimed at improving the metabolic quality of stored units, such as hypoxic storage, ultimately improve performance in the transfused recipient. STUDY DESIGN AND METHODS: Twelve healthy donor volunteers were recruited in a two-arm cross-sectional study, in which each subject donated 2 units to be stored under standard (normoxic) or hypoxic conditions (Hemanext technology). End-of-storage measurements of hemolysis and autologous posttransfusion recovery (PTR) were correlated to metabolomics measurements at Days 0, 21, and 42. RESULTS: Hypoxic red blood cells (RBCs) showed superior PTR and comparable hemolysis to donor-paired standard units. Hypoxic storage improved energy and redox metabolism (glycolysis and 2,3-diphosphoglycerate), improved glutathione and methionine homeostasis, decreased purine oxidation and membrane lipid remodeling (free fatty acid levels, unsaturation and hydroxylation, acyl-carnitines). Intra- and extracellular metabolites in these pathways (including some dietary purines) showed significant correlations with PTR and hemolysis, though the degree of correlation was influenced by sulfur dioxide (SO2 ) levels. CONCLUSION: Hypoxic storage improves energy and redox metabolism of stored RBCs, which results in improved posttransfusion recoveries in healthy autologous recipients-a Food and Drug Administration gold standard of stored blood quality. In addition, we identified candidate metabolic predictors of PTR for RBCs stored under standard and hypoxic conditions.

Development of a flow standard to enable highly reproducible measurements of deformability of stored red blood cells in a microfluidic device.

BACKGROUND: Great deformability allows red blood cells (RBCs) to flow through narrow capillaries in tissues. A number of microfluidic devices with capillary-like microchannels have been developed to monitor storage-related impairment of RBC deformability during blood banking operations. This proof-of-concept study describes a new method to standardize and improve reproducibility of the RBC deformability measurements using one of these devices. STUDY DESIGN AND METHODS: The rate of RBC flow through the microfluidic capillary network of the microvascular analyzer (MVA) device made of polydimethylsiloxane was measured to assess RBC deformability. A suspension of microbeads in a solution of glycerol in phosphate-buffered saline was developed to be used as an internal flow rate reference alongside RBC samples in the same device. RBC deformability and other in vitro quality markers were assessed weekly in six leukoreduced RBC concentrates (RCCs) dispersed in saline-adenine-glucose-mannitol additive solution and stored over 42 days at 4°C. RESULTS: The use of flow reference reduced device-to-device measurement variability from 10% to 2%. Repeated-measure analysis using the generalized estimating equation (GEE) method showed a significant monotonic decrease in relative RBC flow rate with storage from Week 0. By the end of storage, relative RBC flow rate decreased by 22 ± 6% on average. CONCLUSIONS: The suspension of microbeads was successfully used as a flow reference to increase reproducibility of RBC deformability measurements using the MVA. Deformability results suggest an early and late aging phase for stored RCCs, with significant decreases between successive weeks suggesting a highly sensitive measurement method.

Improved in vitro quality of stored red blood cells upon oxygen reduction prior to riboflavin/UV light treatment of whole blood.

BACKGROUND: The application of riboflavin/UV-based pathogen inactivation (PI) to whole blood (WB) is currently limited by its negative impact on red blood cell (RBC) quality. The generation of reactive oxidative species in RBC products contributes to increased hemolysis. This study evaluated the impact of deoxygenation of WB prior to riboflavin/UV light treatment versus deoxygenation of RBC concentrates after PI treatment by monitoring RBC in vitro quality parameters. STUDY DESIGN AND METHODS: Six ABO-matched WB units were pooled and split. Within three pairs, one unit was treated with riboflavin/UV light while the other was kept as an untreated control prior to manufacture into red cell concentrates (RCCs). The first pair (Cntr; Cntr-PI) served as the normoxic controls. Deoxygenation was performed at the RCC level for the second pair (RCCdeox; PI-RCCdeox), and at the WB level of the third pair (WBdeox; WBdeox-PI). In vitro qualities of the respective RBC units were assessed throughout storage. RESULTS: The data for the Cntr and Cntr-PI units were comparable to previous reports. The PI-RCCdeox units exhibited worse in vitro quality for most parameters tested compared to Cntr-PI and WBdeox-PI units throughout storage. Hemolysis and microvesicle release was significantly (p < 0.05) higher on Days 21 and 42 in Cntr-PI units compared to WBdeox-PI units. CONCLUSION: WB deoxygenation may help to decrease the accelerated deterioration in RCC in vitro quality caused by treatment with riboflavin/UV light. Treatment of WB under reduced oxygen levels needs to be assessed for PI effectiveness.

Oxidative modifications of glyceraldehyde 3-phosphate dehydrogenase regulate metabolic reprogramming of stored red blood cells.

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) plays a key regulatory function in glucose oxidation by mediating fluxes through glycolysis or the pentose phosphate pathway (PPP) in an oxidative stress-dependent fashion. Previous studies documented metabolic reprogramming in stored red blood cells (RBCs) and oxidation of GAPDH at functional residues upon exposure to pro-oxidants diamide and H2O2 Here we hypothesize that routine storage of erythrocyte concentrates promotes metabolic modulation of stored RBCs by targeting functional thiol residues of GAPDH. Progressive increases in PPP/glycolysis ratios were determined via metabolic flux analysis after spiking (13)C1,2,3-glucose in erythrocyte concentrates stored in Additive Solution-3 under blood bank conditions for up to 42 days. Proteomics analyses revealed a storage-dependent oxidation of GAPDH at functional Cys152, 156, 247, and His179. Activity loss by oxidation occurred with increasing storage duration and was progressively irreversible. Irreversibly oxidized GAPDH accumulated in stored erythrocyte membranes and supernatants through storage day 42. By combining state-of-the-art ultra-high-pressure liquid chromatography-mass spectrometry metabolic flux analysis with redox and switch-tag proteomics, we identify for the first time ex vivo functionally relevant reversible and irreversible (sulfinic acid; Cys to dehydroalanine) oxidations of GAPDH without exogenous supplementation of excess pro-oxidant compounds in clinically relevant blood products. Oxidative and metabolic lesions, exacerbated by storage under hyperoxic conditions, were ameliorated by hypoxic storage. Storage-dependent reversible oxidation of GAPDH represents a mechanistic adaptation in stored erythrocytes to promote PPP activation and generate reducing equivalents. Removal of irreversibly oxidized, functionally compromised GAPDH identifies enhanced vesiculation as a self-protective mechanism in ex vivo aging erythrocytes.

Hypoxia modulates the purine salvage pathway and decreases red blood cell and supernatant levels of hypoxanthine during refrigerated storage.

Hypoxanthine catabolism in vivo is potentially dangerous as it fuels production of urate and, most importantly, hydrogen peroxide. However, it is unclear whether accumulation of intracellular and supernatant hypoxanthine in stored red blood cell units is clinically relevant for transfused recipients. Leukoreduced red blood cells from glucose-6-phosphate dehydrogenase-normal or -deficient human volunteers were stored in AS-3 under normoxic, hyperoxic, or hypoxic conditions (with oxygen saturation ranging from <3% to >95%). Red blood cells from healthy human volunteers were also collected at sea level or after 1-7 days at high altitude (>5000 m). Finally, C57BL/6J mouse red blood cells were incubated in vitro with 13C1-aspartate or 13C5-adenosine under normoxic or hypoxic conditions, with or without deoxycoformycin, a purine deaminase inhibitor. Metabolomics analyses were performed on human and mouse red blood cells stored for up to 42 or 14 days, respectively, and correlated with 24 h post-transfusion red blood cell recovery. Hypoxanthine increased in stored red blood cell units as a function of oxygen levels. Stored red blood cells from human glucose-6-phosphate dehydrogenase-deficient donors had higher levels of deaminated purines. Hypoxia in vitro and in vivo decreased purine oxidation and enhanced purine salvage reactions in human and mouse red blood cells, which was partly explained by decreased adenosine monophosphate deaminase activity. In addition, hypoxanthine levels negatively correlated with post-transfusion red blood cell recovery in mice and - preliminarily albeit significantly - in humans. In conclusion, hypoxanthine is an in vitro metabolic marker of the red blood cell storage lesion that negatively correlates with post-transfusion recovery in vivo Storage-dependent hypoxanthine accumulation is ameliorated by hypoxia-induced decreases in purine deamination reaction rates.

Methylation of protein aspartates and deamidated asparagines as a function of blood bank storage and oxidative stress in human red blood cells.

BACKGROUND: Being devoid of de novo protein synthesis capacity, red blood cells (RBCs) have evolved to recycle oxidatively damaged proteins via mechanisms that involve methylation of dehydrated and deamidated aspartate and asparagine residues. Here we hypothesize that such mechanisms are relevant to routine storage in the blood bank. STUDY DESIGN AND METHODS: Within the framework of the REDS-III RBC-Omics (Recipient Epidemiology Donor Evaluation Study III Red Blood Cell-Omics) study, packed RBC units (n = 599) were stored under blood bank conditions for 10, 23, and 42 days and profiled for oxidative hemolysis and time-dependent metabolic dysregulation of the trans-sulfuration pathway. RESULTS: In these units, methionine consumption positively correlated with storage age and oxidative hemolysis. Mechanistic studies show that this phenomenon is favored by oxidative stress or hyperoxic storage (sulfur dioxide >95%), and prevented by hypoxia or methyltransferase inhibition. Through a combination of proteomics approaches and 13 C-methionine tracing, we observed oxidation-induced increases in both Asn deamidation to Asp and formation of methyl-Asp on key structural proteins and enzymes, including Band 3, hemoglobin, ankyrin, 4.1, spectrin beta, aldolase, glyceraldehyde 3-phosphate dehydrogenase, biphosphoglycerate mutase, lactate dehydrogenase and catalase. Methylated regions tended to map proximal to the active site (e.g., N316 of glyceraldehyde 3-phosphate dehydrogenase) and/or residues interacting with the N-terminal cytosolic domain of Band 3. CONCLUSION: While methylation of basic amino acid residues serves as an epigenetic modification in nucleated cells, protein methylation at carboxylate side chains and deamidated asparagines is a nonepigenetic posttranslational sensor of oxidative stress and refrigerated storage in anucleated human RBCs.

Citrate metabolism in red blood cells stored in additive solution-3.

BACKGROUND: Red blood cells (RBCs) are thought to have a relatively simple metabolic network compared to other human cell types. Recent proteomics reports challenge the notion that RBCs are mere hemoglobin carriers with limited metabolic activity. Expanding our understanding of RBC metabolism has key implications in many biomedical areas, including transfusion medicine. STUDY DESIGN AND METHODS: In-gel digestion coupled with mass spectrometric analysis proteomics approaches were combined with state-of-the-art tracing experiments by incubating leukofiltered RBCs in additive solution-3 for up to 42 days under blood bank conditions, in presence of 13 C1,2,3 -glucose, 2,2,4,4-d-citrate, and 13 C,15 N-glutamine. RESULTS: Results indicate that the pentose phosphate pathway/glycolysis ratio increases during storage in additive solution-3. While the majority of supernatant glucose is consumed to fuel glycolysis, incorporation of glucose-derived pentose phosphate moieties was observed in nucleoside monophosphates. Incubation with deuterated citrate indicated that citrate uptake and metabolism contribute to explain the origin of up to approximately 20% to 30% lactate that could not be explained by glucose oxidation and 2,3-diphosphoglycerate consumption alone. Incubation with 13 C,15 N-glutamine showed that glutaminolysis fuels transamination reactions and accumulation of millimolar levels of 5-oxoproline, while de novo glutathione synthesis was not significantly active during refrigerated storage. CONCLUSION: Quantitative tracing metabolic experiments revealed that mature RBCs can metabolize other substrates than glucose, such as citrate, an observation relevant to transfusion medicine (i.e., formulation of novel additives), and other research endeavors where metabolic modulation of RBCs opens potential avenues for therapeutic interventions, such as in sickle cell disease.

CO2 -dependent metabolic modulation in red blood cells stored under anaerobic conditions.

BACKGROUND: Anaerobic red blood cell (RBC) storage reduces oxidative damage, maintains adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (DPG) levels, and has superior 24-hour recovery at 6 weeks compared to standard storage. This study will determine if removal of CO2 during O2 depletion by gas exchange may affect RBCs during anaerobic storage. STUDY DESIGN AND METHODS: This is a matched three-arm study (n = 14): control, O2 and CO2 depleted with Ar (AN), and O2 depleted with 95%Ar/5%CO2 (AN[CO2 ]). RBCs in additives AS-3 or OFAS-3 were evenly divided into three bags, and anaerobic conditions were established by gas exchange. Bags were stored at 1 to 6°C in closed chambers under anaerobic conditions or ambient air, sampled weekly for up to 9 weeks for a panel of in vitro tests. A full metabolomics screening was conducted for the first 4 weeks of storage. RESULTS: Purging with Ar (AN) results in alkalization of the RBC and increased glucose consumption. The addition of 5% CO2 to the purging gas prevented CO2 loss with an equivalent starting and final pH and lactate to control bags (p > 0.5, Days 0-21). ATP levels are higher in AN[CO2 ] (p < 0.0001). DPG was maintained beyond 2 weeks in the AN arm (p < 0.0001). Surprisingly, DPG was lost at the same rate in both control and AN[CO2 ] arms (p = 0.6). CONCLUSION: Maintenance of ATP in the AN[CO2 ] arm demonstrates that ATP production is not solely a function of the pH effect on glycolysis. CO2 in anaerobic storage prevented the maintenance of DPG, and DPG production appears to be pH dependent. CO2 as well as O2 depletion provides metabolic advantage for stored RBCs.

Hypoxically stored RBC resuscitation in a rat model of traumatic brain injury and severe hemorrhagic shock.

This study aims to investigate the effects of hypoxically stored Red Blood Cells (RBCs) in a rat model of traumatic brain injury followed by severe hemorrhagic shock (HS) and resuscitation. RBCs were made hypoxic using an O2 depletion system (Hemanext Inc. Lexington, MA) and stored for 3 weeks. Experimental animals underwent craniotomy and blunt brain injury followed by severe HS. Rats were resuscitated with either fresh RBCs (FRBCs), 3-week-old hypoxically stored RBCs (HRBCs), or 3-week-old conventionally stored RBCs (CRBCs). Resuscitation was provided via RBCs transfusion equivalent to 70 % of the shed blood and animals were followed for 2 h. The control group was comprised of healthy animals that were not instrumented or injured. Post-resuscitation hemodynamics and lactate levels were improved with FRBCs and HRBCs, and markers of organ injury in the liver (Aspartate aminotransferase [AST]), lung (chemokine ligand 1 [CXCL-1] and Leukocytes count), and heart (cardiac troponin, Interleukin- 6 [IL-6] and Tumor Necrosis Factor Alpha[TNF-α]) were lower with FRBCs and HRBCs resuscitation compared to CRBCs. Following reperfusion, biomarkers for oxidative stress, lipid peroxidation, and RNA/DNA injury were assessed. Superoxide dismutase [SOD] levels in the HRBCs group were similar to the FRBCs group and levels in both groups were significantly higher than CRBCs. Catalase levels were not different than control values in the FRBCs and HRBCs groups but significantly lower with CRBCs. Thiobarbituric acid reactive substances [Tbars] levels were higher for both CRBCs and HRBCs. Hypoxically stored RBCs show few differences from fresh RBCs in resuscitation from TBI + HS and decreased organ injury and oxidative stress compared to conventionally stored RBCs.

High-Throughput Metabolomics Platform for the Rapid Data-Driven Development of Novel Additive Solutions for Blood Storage.

Red blood cell transfusion is a life-saving intervention, and storage is a logistic necessity to make ~110 million units available for transfusion every year worldwide. However, storage in the blood bank is associated with a progressive metabolic decline, which correlates with the accumulation of morphological lesions, increased intra- and extra-vascular hemolysis upon transfusion, and altered oxygen binding/off-loading kinetics. Prior to storage, red blood cells are suspended in nutrient formulations known as additive solutions to prolong cellular viability. Despite a thorough expansion of knowledge regarding red blood cell biology over the past few decades, only a single new additive solution has been approved by the Food and Drug Administration this century, owing in part to the limited capacity for development of novel formulations. As a proof of principle, we leveraged a novel high-throughput metabolomics technology as a platform for rapid data-driven development and screening of novel additive solutions for blood storage under both normoxic and hypoxic conditions. To this end, we obtained leukocyte-filtered red blood cells (RBCs) and stored them under normoxic or hypoxic conditions in 96 well plates (containing polyvinylchloride plasticized with diethylhexylphthalate to concentrations comparable to full size storage units) in the presence of an additive solution supplemented with six different compounds. To inform this data-driven strategy, we relied on previously identified metabolic markers of the RBC storage lesion that associates with measures of hemolysis and post-transfusion recovery, which are the FDA gold standards to predict stored blood quality, as well as and metabolic predictors of oxygen binding/off-loading parameters. Direct quantitation of these predictors of RBC storage quality were used here-along with detailed pathway analysis of central energy and redox metabolism-as a decision-making tool to screen novel additive formulations in a multiplexed fashion. Candidate supplements are shown here that boost-specific pathways. These metabolic effects are only in part dependent on the SO2 storage conditions. Through this platform, we anticipate testing thousands of novel additives and combinations thereof in the upcoming months.

Effect of Hypoxic Blood Infusion on Pulmonary Physiology.

The ability to store red blood cells (RBCs) and other components for extended periods of time has expanded the availability and use of transfusion as a life-saving therapy. However, conventional RBC storage has a limited window of effective preservation and is accompanied by the progressive accumulation of a series of biochemical and morphological modifications, collectively referred to as "storage lesions." These lesions have been associated with negative clinical outcomes (i.e., postoperative complications as well as reduced short-term and long-term survival) in patients transfused with conventionally stored blood with older and deteriorated transfused red cells. Hence, there is an increased unmet need for improved RBC storage. Hypoxic storage of blood entails the removal of large amounts of oxygen to low levels prior to refrigeration and maintenance of hypoxic levels through the entirety of storage. As opposed to conventionally stored blood, hypoxic storage can lead to a reduction of oxidative damage to slow storage lesion development and create a storage condition expected to result in enhanced efficacy of stored RBCs without an effect on oxygen exchange in the lung. Hypoxic blood transfusions appear to offer minimal safety concerns, even in patients with hypoxemia. This review describes the physiology of hypoxically stored blood, how it differs from conventionally stored blood, and its use in potential clinical application, such as massively transfused and critically ill patients with oxygenation/ventilation impairments.

A deep 96-well plate RBC storage platform for high-throughput screening of novel storage solutions.

Background: Red blood cell (RBC) storage solutions, also known as additive solutions (ASs), first developed in the 1970s, enable extended storage of RBCs. Unfortunately, the advancements in this field have been limited, due to labor intensive and time-consuming serial in vitro and in vivo testing, coupled with very high commercialization hurdles. This study examines the utility of deep 96-well plates for preliminary screenings of novel ASs through comparison of RBC storage with the standard PVC bags in terms of hemolysis and ATP levels, under both normoxic (N) and hypoxic/hypocapnic (H) storage conditions. The necessity for the presence of DEHP, normally provided by PVC bags, is also examined. Materials and methods: A pool of 2 ABO compatible RBC units was split between a bag and a plate. Each plate well contained either 1, 2 or 0 PVC strips cut from standard storage bags to supply DEHP. The H bags and plates were processed in an anaerobic glovebox and stored in O2 barrier bags. Hemolysis and ATP were measured bi-weekly using standard methods. Results: Final ATP and hemolysis values for the plate-stored RBCs were comparable to the typical values observed for 6-week storage of leukoreduced AS-3 RBCs in PVC bags under both N and H conditions. Hemolysis was below FDA and EU benchmarks of 1% and 0.8%, respectively, and excluding DEHP from plates during storage, resulted in an inconsequential increase when compared to bag samples. Discussion: In combination with high-throughput metabolomics workflow, this platform provides a highly efficient preliminary screening platform to accelerate the initial testing and consequent development of novel RBC ASs.

Microfluidic capillary networks are more sensitive than ektacytometry to the decline of red blood cell deformability induced by storage.

Ektacytometry has been the primary method for evaluating deformability of red blood cells (RBCs) in both research and clinical settings. This study was designed to test the hypothesis that the flow of RBCs through a network of microfluidic capillaries could provide a more sensitive assessment of the progressive impairment of RBC deformability during hypothermic storage than ektacytometry. RBC units (n = 9) were split in half, with one half stored under standard (normoxic) conditions and the other half stored hypoxically, for up to 6 weeks. RBC deformability was measured weekly using two microfluidic devices, an artificial microvascular network (AMVN) and a multiplexed microcapillary network (MMCN), and two commercially available ektacytometers (RheoScan-D and LORRCA). By week 6, the elongation indexes measured with RheoScan-D and LORRCA decreased by 5.8-7.1% (5.4-6.9% for hypoxic storage). Over the same storage duration, the AMVN perfusion rate declined by 27.5% (24.5% for hypoxic) and the MMCN perfusion rate declined by 49.0% (42.4% for hypoxic). Unlike ektacytometry, both AMVN and MMCN measurements showed statistically significant differences between the two conditions after 1 week of storage. RBC morphology deteriorated continuously with the fraction of irreversibly-damaged (spherical) cells increasing significantly faster for normoxic than for hypoxic storage. Consequently, the number of MMCN capillary plugging events and the time MMCN capillaries spent plugged was consistently lower for hypoxic than for normoxic storage. These data suggest that capillary networks are significantly more sensitive to both the overall storage-induced decline of RBC deformability, and to the differences between the two storage conditions, than ektacytometry.

Hypoxia and hypocapnia storage of γ-irradiated red cell concentrates.

BACKGROUND: γ-irradiation is used to treat red blood cell (RBC) concentrates (RCCs) transfused to immunosuppressed patients. This treatment damages RBCs and increases storage lesions. Several studies have shown the beneficial effect of reducing O2 content during RBC storage. The present research work investigated the effect of γ-irradiation on RCCs stored under normal and hypoxia/hypocapnia conditions. MATERIALS AND METHODS: O2 concentration (measured as oxyhaemoglobin fraction, sO2) and ABO-matched RCCs from whole blood donations, leukoreduced and prepared in phosphate, adenine, glucose, guanosine, saline and mannitol (PAGGSM) were pooled and split in two identical RCCs within 24 h post donation. One bag (Hx) was submitted to O2 and CO2 adsorption for 3 h on an orbital shaker at 22±2 °C and then transferred to a storage bag impermeable to gas. The other bag (Ctrl) was left as it was. The two bags were then stored at 4 °C. γ-irradiation (25 Gy) was applied at day 2 or 14, and the RCCs were stored until day 43. Different parameters (metabolites, haemolysis, morphology) were measured. RESULTS: Starting sO2 values were 63.7±18.4% (n=12) in Ctrl and 20.8±9.8% (n=12) in Hx bags, and reached 90.8±9.1% and 6.6±5.9% at day 43, respectively. As expected, an increase in glycolysis rate was observed after deoxygenation. Extracellular potassium concentrations were identical and reached around 70 mM at expiry with an irradiation-dependent kinetic release. No difference in haemolysis was observed after irradiation on day 2 in either group (<0.40%, p>0.9999). When irradiated at day 14, haemolysis was lower (p=0.033) in RCCs under hypoxia at the end of storage (day 28, 0.67±0.16%) compared to control (1.06±0.33%). Percentages of spherocytes were lower under hypoxia. DISCUSSION: The storage under hypoxia provided equivalent storage when RCCs were irradiated at day 2 and was advantageous when irradiated at day 14. In summary, O2-depletion of RCCs enable a better storage of RBCs, particularly when late irradiation is applied.

Oxygen in Red Blood Cell Concentrates: Influence of Donors' Characteristics and Blood Processing.

Objective: Unexpectedly wide distribution (<10 to >90%) of hemoglobin oxygen saturation (sO2) within red cell concentrates (RCCs) has recently been observed. Causes of such variability are not yet completely explained whereas the roles of oxygen and oxidative lesions during the storage of RCCs are known. The objectives of the present study are to characterize sO2 distribution in RCCs produced in a Swiss blood center and to investigate the influence of processing and donors' characteristics. Methods: The level of sO2 was measured in 1701 leukocyte-depleted RCCs derived from whole blood donations in both top-bottom (TB; component filtered, SAGM) and top-top (TT; whole blood filtration, PAGGSM) RCCs. The sO2 value was measured non-invasively through the PVC bag prior to storage by resonance Raman spectroscopy. Gender, age, blood type, hemoglobin level, and living altitude of donors, as well as process method and time-to-process were recorded. Results: Overall, the sO2 exhibited a wide non-Gaussian distribution with a mean of 51.2 ± 18.5%. Use of top-top kits resulted in a 16% higher sO2 (P < 0.0001) than with top-bottom ones. Waiting time before processing only had a modest impact, but the blood processing itself reduced the sO2 by almost 12% (P < 0.0001). sO2 was also significantly affected by some donors' characteristics. RCCs from men exhibited 25% higher sO2 (P < 0.0001) than those donated by women. Multivariate analysis revealed that the apparent correlation observed with hemoglobin level and age was actually due to multicollinearity with the sex variable. Finally, we noticed no significant differences across blood type but found that altitude of residence was associated with the sO2 (i.e., higher in higher living place). Conclusion: These data confirm wide sO2 distribution in RCCs reported recently. The sO2 was impacted by the processing and also by donors' characteristics such as the gender and the living altitude, but not by the hemoglobin level, blood group and donor age. This study provides new hints on the factors influencing red blood cells storage lesions, since they are known to be related to O2 content within the bags, giving clues to better process and to better store RCCs and therefore potentially improve the efficacy of transfusion.