"Red blood cell (RBC) transfusion has become a highly organized and life-saving component of critical healthcare. Approximately 40,000 units of RBCs are transfused every day in the US, therefore the safety and efficiency of RBC transfusions are essential to patients' health. However, post-transfusion complications still exist, therefore remaining a threat to the patients' life. It is well-known that stored RBCs experience metabolic and physical changes during the storage period, collectively known as the storage lesion, which may cause adverse effects after transfusion. The Spence group hypothesizes that the high concentration of glucose present in the blood storage solutions plays an important role in the development of the storage lesion. In order to improve the quality of stored RBCs, normoglycemic versions for the current FDA approved blood storage solutions have been proposed, where the glucose concentrations were modified to 5.5 mM. The benefits of normoglycemic storage of RBCs were quantitatively evaluated through a variety of experiments. First, flow-induced ATP released from stored RBCs was studied using a 3D-printed fluidic device. It is well-known that the primary function of the RBC is to deliver oxygen to tissues. Besides that, the RBC acts as a blood flow regulator by releasing adenosine triphosphate (ATP) into the blood stream. RBC-derived ATP release can stimulate nitric oxide (NO), a known vasodilator, production within endothelial cells, increasing blood flow. RBC derived-ATP release decreases approximately 50% when cells are stored in hyperglycemic environments, compared to normoglycemic storage. This result indicates that RBCs stored in normoglycemic conditions may have improved blood flow during and after transfusion. Next, the mechanism of impaired ATP release was explored by studying cell deformability. This work was done by applying a 3D-printed, multi-port membrane based device accompanied with flow cytometry for cell counting. It is shown that RBCs stored in hyperglycemia lost 15 - 20% of their deformability. One possible element causing cell deformability loss is oxidative damage triggered by the massive production of intracellular sorbitol from RBCs stored in standard storage solutions. In order to further discover the mechanisms of concentrated glucose damage to stored RBCs, cell membrane phosphatidylethanolamine (PE) glycation was analyzed by a high resolution/accurate mass spectrometry. The results showed that the glycated product of PE, Amadori-PE, to normal PE ratio on the RBC membrane decreases as a function of time during the storage period when cells are stored in physiological levels of glucose. In summary, the work here demonstrates that the excess glucose present in storage solutions might be the main contributor for the development of storage lesions. Alternatively, storing RBCs in normoglycemic conditions can reduce the severity of those deleterious effects, therefore having high potential benefits in the clinic."--Pages ii-iii.
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