| Description |
- Background: Red blood cells (RBCs), in addition to carrying oxygen, generate and export vasoregulatory mediators as a function of their metabolic context. S- nitrosothiol (SNO) is exported to effect hypoxic vasodilation, a fundamental vascular reflex dependent on RBCs. This O2-sensitive, allosterically governed blood flow regulation by S- nitrosohemoglobin (SNO-Hb) ensures efficient and well-distributed tissue oxygenation. The generation and export of adenosine triphosphate (ATP) and SNO also assist in the maintenance of RBC deformability necessary for its efficient transit through narrow capillaries and the ability of RBCs to resist adhesion to endothelial cells. RBC transfusion is a vital tool for the anesthesiologist in the operating room, but conventional RBC storage leads to the development of storage lesions that compromise RBC quality. Multiple new storage strategies have been developed to mitigate these lesions. Recently, a method of hypoxic RBC storage has been FDA approved. This alternative storage method, trade name Hemanext, mitigates oxidative stress (driven by abundant O2) and thus storage lesion development, and preserves BPG (aka diphosphoglycerate or 2,3-DPG) and to some extent ATP. Hypoxic RBC storage has been shown to provide a protective influence on the appearance of RBC senescence markers (ROS increases, phosphatidylserine exposure, and calcium entry), and favorably influenced outcomes in a rat transfusion model. How this storage method affects RBC export of ATP or SNO is unknown.
Methods: We prepared 12 units of hypoxic stored RBCs and 6 control units. Of the 12 hypoxic units, 6 underwent CO2 repletion during the deoxygenation reaction process (which otherwise profoundly depletes CO2 as well as O2) and 6 underwent the standard Hemanext procedure. The units were stored and sampled over the course of 6 weeks with supernatant saved for future assays.
Results: The average sO2 in the hypoxically stored RBC units was 6.3 and 6.2 for the CO2 repleted and standard Hemanext procedure respectively, and 61.2 in the control units. The average pCO2 of the CO2 repleted group and control group were 90.8 and 104.2, respectively, while standard Hemanext procedure units pCO2 average was 26.1.
Conclusions: Our study establishes a reliable method of hypoxic blood storage and sampling technique for the assessment of RBC ATP and SNO export throughout the storage duration. Currently, vasomediator assays are underway to complete the study to understand how this novel RBC storage approach might influence responses to RBC transfusion.
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