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

Red blood cell urate levels are linked to hemolysis in vitro and post-transfusion as a function of donor sex, population and genetic polymorphisms in SLC2A9 and ABCG2

BACKGROUND

Storage of packed red blood cells (RBCs) for transfusion leads to biochemical and morphological changes, increasing hemolysis risk. Urate levels in blood bags at donation contribute to the molecular heterogeneity and hemolytic propensity of stored RBCs. However, studies to date have been underpowered to investigate at scale the contribution of donor demographics and genetics to the heterogeneity in urate levels across donations.

STUDY DESIGN AND METHODS

Urate levels were measured in 13,091 RBC units from the REDS study. Characteristics tested included hemolysis parameters (spontaneous, osmotic, oxidative) at storage end and post-transfusion hemoglobin (Hb) increments in recipients. Donor demographics, urate levels, and genetic variants were analyzed for associations with these outcomes.

RESULTS

Elevated urate levels were linked to male sex, older age, high BMI, and Asian descent. Units with high urate levels exhibited increased spontaneous and osmotic hemolysis, while oxidative hemolysis was unaffected. Genetic variants in SLC2A9 (V282I) and ABCG2 (Q141K) were strongly associated with elevated urate, particularly in Asian donors. Post-transfusion analyses revealed that units from female donors carrying these variants were associated with reduced Hb increments, with up to a 31% reduction in efficacy. This effect was not observed in male donors.

DISCUSSION

RBC urate levels and genetic traits significantly impact storage quality and transfusion outcomes. These findings highlight the importance of donor molecular characteristics for optimizing transfusion strategies. Moreover, genetic and metabolic insights may inform donor recruitment efforts, providing health feedback to volunteers while ensuring effective transfusion products.

Molecular modifications to mitigate oxidative stress and improve red blood cell storability

The development of red blood cell (RBC) storage lesion during hypothermic storage has long posed challenges for blood transfusion efficacy. These alterations are primarily driven by oxidative stress, concern both structural and biochemical aspects of RBCs, and affect their interactions with the recipient's tissues post-transfusion. Efforts to counteract these effects focus on improving the antioxidant capacity within stored RBCs, reducing oxygen exposure, and scavenging harmful molecules that accumulate during storage. Various supplements, such as ascorbic acid, N-acetylcysteine, polyphenolic compounds, and specific metabolites have shown the potential to improve RBC quality by reducing oxidative lesions and lysis phenomena, and enhancing antioxidant, energy, or proteostasis networks. Accordingly, anaerobic storage has emerged as a promising strategy, demonstrating improved RBC storability and recovery in both animal models and preliminary human studies. Finally, targeted scavenging of harmful storage-related phenotypes and molecules, like removal signals, oxidized proteins, and extracellular hemoglobin, while not so studied, also has the potential to benefit both the unit and the patient in need. Omics technologies have aided a lot in these endeavors by revealing biomarkers of superior storability and, thus, potential novel supplementation strategies. Nonetheless, while the so far examined storage modifications show significant promise, there are not many post-transfusion studies (either in vitro, in animal models, or humans) to evaluate RBC efficacy in the transfusion setting. Looking ahead, the future of blood storage and transfusion will likely depend on the optimization of these interventions to extend the shelf-life and quality of stored RBCs, as well as their therapeutic outcome.

Prevalence of anemia of varying severity, geographic variations, and association with metabolic factors among women of reproductive age in China: a nationwide, population-based study

To investigate the epidemiological characteristics of anemia of varying severity among women of reproductive age, we conducted a nationwide, cross-sectional study between January 1, 2019 and December 31, 2019, including 4 184 547 nonpregnant women aged 18-49 years from all 31 provinces in the mainland of China. Anemia was defined as having hemoglobin concentration < 120.0 g/L and categorized as mild, moderate, and severe. Multivariate logistic models with cluster effect were used to explore the association of anemia and metabolic risk factors. The standardized prevalence of anemia and moderate and worse anemia among women of reproductive age in China was 15.8% (95% CI 15.1%-16.6%) and 6.6% (6.3%-7.0%), respectively. The prevalence of anemia and the proportion of moderate and worse anemia significantly increased with age. We also observed great geographic variations in the prevalence of anemia, with a high likelihood in south, central, and northwest China. Moderate and/or severe anemia was positively associated with overweight and obesity, diabetes, and impaired kidney function. In conclusion, anemia remains a significant challenge for women of reproductive age in China. Geographic variations and metabolic risk factors should be considered in the comprehensive and targeting strategy for anemia reduction.

Impact of Different Red Blood Cell Storage Solutions and Conditions on Cell Function and Viability: A Systematic Review

Red blood cell (RBC) storage solutions have evolved significantly over the past decades to optimize the preservation of cell viability and functionality during hypothermic storage. This comprehensive review provides an in-depth analysis of the effects of various storage solutions and conditions on critical RBC parameters during refrigerated preservation. A wide range of solutions, from basic formulations such as phosphate-buffered saline (PBS), to advanced additive solutions (ASs), like AS-7 and phosphate, adenine, glucose, guanosine, saline, and mannitol (PAGGSM), are systematically compared in terms of their ability to maintain key indicators of RBC integrity, including adenosine triphosphate (ATP) levels, morphology, and hemolysis. Optimal RBC storage requires a delicate balance of pH buffering, metabolic support, oxidative damage prevention, and osmotic regulation. While the latest alkaline solutions enable up to 8 weeks of storage, some degree of metabolic and morphological deterioration remains inevitable. The impacts of critical storage conditions, such as the holding temperature, oxygenation, anticoagulants, irradiation, and processing methods, on the accumulation of storage lesions are also thoroughly investigated. Personalized RBC storage solutions, tailored to individual donor characteristics, represent a promising avenue for minimizing storage lesions and enhancing transfusion outcomes. Further research integrating omics profiling with customized preservation media is necessary to maximize post-transfusion RBC survival and functions. The continued optimization of RBC storage practices will not only enhance transfusion efficacy but also enable blood banking to better meet evolving clinical needs.

Phosphoproteomics and morphology of stored human red blood cells treated by protein tyrosine phosphatases inhibitor

ABSTRACT

The process of protein phosphorylation is involved in numerous cell functions. In particular, phosphotyrosine (pY) has been reported to play a role in red blood cell (RBC) functions, including the cytoskeleton organization. During their storage before transfusion, RBCs suffer from storage lesions that affect their energy metabolism and morphology. This study investigated the relationship between pY and the storage lesions. To do so, RBCs were treated (in the absence of calcium) with a protein tyrosine phosphatase inhibitor (orthovanadate [OV]) to stimulate phosphorylation and with 3 selective kinase inhibitors (KIs). Erythrocyte membrane proteins were studied by western blot analyses and phosphoproteomics (data are available via ProteomeXchange with identifier PXD039914) and cell morphology by digital holographic microscopy. The increase of pY triggered by OV treatment (inducing a global downregulation of pS and pT) disappeared during the storage. Phosphoproteomic analysis identified 609 phosphoproteins containing 1752 phosphosites, of which 41 pY were upregulated and 2 downregulated by OV. After these phosphorylation processes, the shape of RBCs shifted from discocytes to spherocytes, and the addition of KIs partially inhibited this transition. The KIs modulated either pY or pS and pT via diverse mechanisms related to cell shape, thereby affecting RBC morphology. The capacity of RBCs to maintain their function is central in transfusion medicine, and the presented results contribute to a better understanding of RBC biology.

The Effect of the Donor's and Recipient's Sex on Red Blood Cells Evaluated Using Transfusion Simulations

The hypothesis of the potential impact of the sex of red blood cell (RBC) concentrate (RCC) donors, as well as the sex of the recipients, on the clinical outcome, is still under evaluation. Here, we have evaluated the sex impact on RBC properties using in vitro transfusion models. Using a "flask model", RBCs from RCCs (representing the donor)-at different storage lengths-were incubated in a sex-matched and sex-mismatched manner with fresh frozen plasma pools (representing the recipient) at 37 °C, with 5% of CO2 up to 48 h. Standard blood parameters, hemolysis, intracellular ATP, extracellular glucose and lactate were quantified during incubation. Additionally, a "plate model", coupling hemolysis analysis and morphological study, was carried out in similar conditions in 96-well plates. In both models, RBCs from both sexes hemolyzed significantly less in female-derived plasma. No metabolic or morphological differences were observed between sex-matched and -mismatched conditions, even though ATP was higher in female-derived RBCs during incubations. Female plasma reduced hemolysis of female- as well as male-derived RBCs, which may be related to a sex-dependent plasma composition and/or sex-related intrinsic RBC properties.

The relationship between hyperuricemia and anemia and metabolic syndrome in Korean adults: The Korea National Health and Nutrition Examination Survey 2019

AIM

The present study was conducted to assess the relationship between hyperuricemia and anemia in Korean adults with or without metabolic syndrome (MetS).

METHODS

Data from 6073 adults (age ≥ 20 years) in the Eighth Korean National Health and Nutrition Examination Survey (2019) were analyzed.

RESULTS

Several key findings were identified. First, after adjusting for the related variables, the hemoglobin [Hb] level in the hyperuricemia subgroup (uric acid [UA] ≥ 7.0 mg/dL in men or ≥ 6.0 mg/dL in women) was higher than in the normouricemia subgroup (UA < 7.0 mg/dL in men or < 6.0 mg/dL in women) in subjects with non-MetS (p = 0.005), whereas it was lower than in the normouricemia subgroup in subjects with MetS (p = 0.032). Second, after adjusting for the related variables, the odds ratio (OR) of anemia (Hb < 13.0 g/dL in men or < 12 g/dL in women), using the normouricemia subgroup as a reference, was negatively significant for the hyperuricemia subgroup in subjects with non-MetS (OR, 0.478; 95 % CI, 0.300-0.761) but positively significant for the hyperuricemia subgroup in subjects with MetS (OR, 1.765; 95 % CI, 1.160-2.198).

CONCLUSIONS

Hyperuricemia was associated with a decrease in anemia in non-MetS but an increase in anemia in MetS.

Oxidants and Antioxidants in the Redox Biochemistry of Human Red Blood Cells

Red blood cells (RBCs) are exposed to both external and internal sources of oxidants that challenge their integrity and compromise their physiological function and supply of oxygen to tissues. Autoxidation of oxyhemoglobin is the main source of endogenous RBC oxidant production, yielding superoxide radical and then hydrogen peroxide. In addition, potent oxidants from other blood cells and the surrounding endothelium can reach the RBCs. Abundant and efficient enzymatic systems and low molecular weight antioxidants prevent most of the damage to the RBCs and also position the RBCs as a sink of vascular oxidants that allow the body to maintain a healthy circulatory system. Among the antioxidant enzymes, the thiol-dependent peroxidase peroxiredoxin 2, highly abundant in RBCs, is essential to keep the redox balance. A great part of the RBC antioxidant activity is supported by an active glucose metabolism that provides reducing power in the form of NADPH via the pentose phosphate pathway. There are several RBC defects and situations that generate oxidative stress conditions where the defense mechanisms are overwhelmed, and these include glucose-6-phosphate dehydrogenase deficiencies (favism), hemoglobinopathies like sickle cell disease and thalassemia, as well as packed RBCs for transfusion that suffer from storage lesions. These oxidative stress-associated pathologies of the RBCs underline the relevance of redox balance in these anucleated cells that lack a mechanism of DNA-inducible antioxidant response and rely on a complex and robust network of antioxidant systems.

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

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

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

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

Storage of red blood cell concentrates: Clinical impact

The storage of red blood cells for transfusion purposes induces modifications of biochemical and biological properties. Moreover, these modifications are modulated by the donors' characteristics and the cell processing. These ex vivo alterations were suspected to decrease the transfusion efficiency and even to induce adverse events. This short article will review the red blood cells storage lesions and the clinical data related to them. In particular, the questions regarding the donors and recipients sex will be discussed.

Deep Learning-based Phenotypic Assessment of Red Cell Storage Lesions for Safe Transfusions

This study presents a novel approach to automatically perform instant phenotypic assessment of red blood cell (RBC) storage lesion in phase images obtained by digital holographic microscopy. The proposed model combines a generative adversarial network (GAN) with marker-controlled watershed segmentation scheme. The GAN model performed RBC segmentations and classifications to develop ageing markers, and the watershed segmentation was used to completely separate overlapping RBCs. Our approach achieved good segmentation and classification accuracy with a Dices coefficient of 0.94 at a high throughput rate of about 152 cells per second. These results were compared with other deep neural network architectures. Moreover, our image-based deep learning models recognized the morphological changes that occur in RBCs during storage. Our deep learning-based classification results were in good agreement with previous findings on the changes in RBC markers (dominant shapes) affected by storage duration. We believe that our image-based deep learning models can be useful for automated assessment of RBC quality, storage lesions for safe transfusions, and diagnosis of RBC-related diseases.

Image- and Fluorescence-Based Test Shows Oxidant-Dependent Damages in Red Blood Cells and Enables Screening of Potential Protective Molecules

An increase of oxygen saturation within blood bags and metabolic dysregulation occur during storage of red blood cells (RBCs). It leads to the gradual exhaustion of RBC antioxidant protective system and, consequently, to a deleterious state of oxidative stress that plays a major role in the apparition of the so-called storage lesions. The present study describes the use of a test (called TSOX) based on fluorescence and label-free morphology readouts to simply and quickly evaluate the oxidant and antioxidant properties of various compounds in controlled conditions. Here, TSOX was applied to RBCs treated with four antioxidants (ascorbic acid, uric acid, trolox and resveratrol) and three oxidants (AAPH, diamide and H₂O₂) at different concentrations. Two complementary readouts were chosen: first, where ROS generation was quantified using DCFH-DA fluorescent probe, and second, based on digital holographic microscopy that measures morphology alterations. All oxidants produced an increase of fluorescence, whereas H₂O₂ did not visibly impact the RBC morphology. Significant protection was observed in three out of four of the added molecules. Of note, resveratrol induced diamond-shape “Tirocytes”. The assay design was selected to be flexible, as well as compatible with high-throughput screening. In future experiments, the TSOX will serve to screen chemical libraries and probe molecules that could be added to the additive solution for RBCs storage.

Why Does Hyperuricemia Not Necessarily Induce Gout?

Hyperuricemia is a risk factor for gout. It has been well observed that a large proportion of individuals with hyperuricemia have never had a gout flare(s), while some patients with gout can have a normuricemia. This raises a puzzle of the real role of serum uric acid (SUA) in the occurrence of gout flares. As the molecule of uric acid has its dual effects in vivo with antioxidant properties as well as being an inflammatory promoter, it has been placed in a delicate position in balancing metabolisms. Gout seems to be a multifactorial metabolic disease and its pathogenesis should not rely solely on hyperuricemia or monosodium urate (MSU) crystals. This critical review aims to unfold the mechanisms of the SUA role participating in gout development. It also discusses some key elements which are prerequisites for the formation of gout in association with the current therapeutic regime. The compilation should be helpful in precisely fighting for a cure of gout clinically and pharmaceutically.