Red blood cell (RBC) transfusions are life-saving procedures for a wide variety of patient populations, resulting in nearly 30,000 transfusions each day within the United Sates. However, transfusions can also result in complications for patients, including inflammation, edema, infection, and organ dysfunction. These poor transfusion outcomes may be related to irreversible chemical and physical damages that occur to RBCs during storage, called the “storage lesion”. These damages, including diminished ATP production/release, decreased deformability, increased oxidative stress, and increased membrane damage, may result in poor functionality when transfused. The damage that occurs during storage may be due to the hyperglycemic nature of current anticoagulants and additive solutions used for RBC storage. All FDA approved storage solutions contain glucose at concentrations that are over 8x higher than the blood stream of a healthy individual. Previous work has already shown that storing RBCs at physiological concentrations of glucose (4-6 mM), or normoglycemic conditions, resulted in the alleviation of many storage-induced damages, including an increase in ATP release, increased deformability, reduced osmotic fragility, and decreased oxidative stress. However, this storage technique was also accompanied by many limitations in its translation to clinical practice. The manual feeding of glucose to normoglycemic stored RBCs to maintain physiological levels of glucose introduced both a breach in sterility and unreasonable labor requirements that could not be translated to clinical practice. Additionally, the low-volume storage (< 2 mL) method with custom PVC bags used in previous work may not illicit similar benefits when scaled up to larger volumes with commercially available blood collection bags. This work overcame these limitations through the design and implementation of an autonomous glucose delivery system that maintained normoglycemia of stored RBCs autonomously for 39 days in storage, while also maintaining sterility. This system was then used to store RBCs under normoglycemic conditions and monitor key storage lesion indicators, resulting in reduced osmotic fragility, decreased oxidative stress, and reduced morphological changes. There was also no impact on glycolytic activity or hemolysis levels, improving upon previous work which reported significant hemolysis that surpassed the FDA threshold of 1%. These data solidify and improve upon previous results, indicating that normoglycemic RBC storage results in reduced damages in storage that may translate to better in vivo function. The autonomous glucose delivery system also significantly advances the applicability of the normoglycemic storage technique to clinical practice, making large scale studies now possible. An alternative strategy to combat RBC storage-induced damage was investigated through the use of albumin as a novel rejuvenating agent. Albumin, a 66 kDa protein, was able to reverse the echinocytic shape transformations seen during RBC storage, resulting in RBCs closer in shape and size to that of fresh RBCs. These data indicate that this phenomenon is likely due to a change in the Donnan equilibrium that reverses echinocytosis, resulting in a recovery of RBC shape and size. Rejuvenation of stored RBCs with albumin had no impact on phosphatidylserine externalization, reactive oxygen species generation, or osmotic fragility in comparison to a buffer without albumin, supporting the hypothesis that rejuvenation does not occur via lipid interaction, osmotic changes, or antioxidant abilities of albumin, but rather by alteration of the Donnan equilibrium in favor of stomatocytosis. These data highlight a possible mechanism responsible for RBC rejuvenation via albumin that may result in improved in vivo function.
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