Deoxygenation of leucofiltered erythrocyte concentrates preserves proteome stability during storage in the blood bank

Red blood cell storage lesion: causes and potential clinical consequences

Red blood cells (RBCs) are a specialised organ that enabled the evolution of multicellular organisms by supplying a sufficient quantity of oxygen to cells that cannot obtain oxygen directly from ambient air via diffusion, thereby fueling oxidative phosphorylation for highly efficient energy production. RBCs have evolved to optimally serve this purpose by packing high concentrations of haemoglobin in their cytosol and shedding nuclei and other organelles. During their circulatory lifetimes in humans of approximately 120 days, RBCs are poised to transport oxygen by metabolic/redox enzymes until they accumulate damage and are promptly removed by the reticuloendothelial system. These elaborate evolutionary adaptions, however, are no longer effective when RBCs are removed from the circulation and stored hypothermically in blood banks, where they develop storage-induced damages ("storage lesions") that accumulate over the shelf life of stored RBCs. This review attempts to provide a comprehensive view of the literature on the subject of RBC storage lesions and their purported clinical consequences by incorporating the recent exponential growth in available data obtained from "omics" technologies in addition to that published in more traditional literature. To summarise this vast amount of information, the subject is organised in figures with four panels: i) root causes; ii) RBC storage lesions; iii) physiological effects; and iv) reported outcomes. The driving forces for the development of the storage lesions can be roughly classified into two root causes: i) metabolite accumulation/depletion, the target of various interventions (additive solutions) developed since the inception of blood banking; and ii) oxidative damages, which have been reported for decades but not addressed systemically until recently. Downstream physiological consequences of these storage lesions, derived mainly by in vitro studies, are described, and further potential links to clinical consequences are discussed. Interventions to postpone the onset and mitigate the extent of the storage lesion development are briefly reviewed. In addition, we briefly discuss the results from recent randomised controlled trials on the age of stored blood and clinical outcomes of transfusion.

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.

Metabolomics in transfusion medicine

Biochemical investigations on the regulatory mechanisms of red blood cell (RBC) and platelet (PLT) metabolism have fostered a century of advances in the field of transfusion medicine. Owing to these advances, storage of RBCs and PLT concentrates has become a lifesaving practice in clinical and military settings. There, however, remains room for improvement, especially with regard to the introduction of novel storage and/or rejuvenation solutions, alternative cell processing strategies (e.g., pathogen inactivation technologies), and quality testing (e.g., evaluation of novel containers with alternative plasticizers). Recent advancements in mass spectrometry-based metabolomics and systems biology, the bioinformatics integration of omics data, promise to speed up the design and testing of innovative storage strategies developed to improve the quality, safety, and effectiveness of blood products. Here we review the currently available metabolomics technologies and briefly describe the routine workflow for transfusion medicine-relevant studies. The goal is to provide transfusion medicine experts with adequate tools to navigate through the otherwise overwhelming amount of metabolomics data burgeoning in the field during the past few years. Descriptive metabolomics data have represented the first step omics researchers have taken into the field of transfusion medicine. However, to up the ante, clinical and omics experts will need to merge their expertise to investigate correlative and mechanistic relationships among metabolic variables and transfusion-relevant variables, such as 24-hour in vivo recovery for transfused RBCs. Integration with systems biology models will potentially allow for in silico prediction of metabolic phenotypes, thus streamlining the design and testing of alternative storage strategies and/or solutions.

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.