Restoration and Function of S-nitrosothiol in Stored Blood

描述(由申请人提供)： 输注红细胞(RBC)是维持和/或改善组织和终末器官氧输送的最常见的治疗干预措施。尽管这种治疗在概念上很简单，但最近的研究表明，异基因红细胞输注通常不会产生多少临床益处，实际上可能会损害受者的健康。我们最近确定，储存人类血液会导致一氧化氮(NO)生物活性(S-亚硝基-血红蛋白)的迅速丧失，这与储存的红细胞扩张血管从而输送氧气的能力的丧失完全平行。我们进一步证明，通过补充无生物活性，缺陷被纠正。我们现在还发现，长时间储存会导致S-亚硝基-红细胞再生的缺陷(即较老的血液表现明显)，这至少是部分可逆的。这种库血失去生理活性的新机制，以及更重要的是对其纠正的假定干预，增加了在给药前恢复无生物活性可能显著改善输血相关缺血发病率的可能性。我们的发现导致了目前的拨款申请，其中我们将检验以下假设：通过肾化来增加S-亚硝基-血红蛋白的含量，恢复储存的红细胞的缺氧-血管扩张活性，以改善组织的氧输送和输血期间的生理状态。 研究目标： 1.优化和验证体外大规模重氮缩合的方法，以恢复不同血型和不同储存条件下储存的红细胞的缺氧血管活性；以及 2.进行有针对性的体内评估，以证明输血前肾氨酸化对血流和局部氧气输送的好处。 通过本文详细介绍的一系列工作台、临床前和临床实验，我们将建立大规模的方法来重硝化储存的血液，并彻底评估其生理益处。我们预计，这些研究产生的信息可能会影响临床护理的根本性变化。恢复储存的红细胞的无生物活性和氧气输送能力将导致输血达到其临床目的：在微循环中扩张血管，以维持或增强贫血患者的终末器官氧气输送。肾氨酸化将是一种新的治疗措施，非常容易实施，可以产生显著的临床效益和经济节省。 公共卫生相关性： 输血是最常见的医疗程序之一：每年约有500万美国人接受1400万单位的红细胞(RBC)，用于治疗各种急性原因和慢性病状态引起的贫血。然而，现在人们认识到，给药填充红细胞不仅不能改善氧气输送，而且实际上可能会加剧缺血。基于红细胞的血管扩张能力受损(由储存相关的一氧化氮生物活性耗尽引起)与输血相关的发病率显著相关这一命题，我们建议在临床环境下建立恢复红细胞一氧化氮生物活性的方法，并确定恢复红细胞血管扩张是否能减轻输血的有害影响。

DESCRIPTION (provided by applicant): Red blood cell (RBC) transfusion is the most common therapeutic intervention employed to maintain and/or improve tissue and end-organ oxygen delivery. Despite the conceptual simplicity of this treatment recent studies indicate that allogenic RBC infusion often produces little clinical benefit and may actually harm the recipient. We recently determined that storage of human blood leads to rapid losses in nitric oxide (NO) bioactivity (S-nitroso-hemoglobin) that are precisely paralleled by losses in the ability of stored RBCs to dilate blood vessels and thereby deliver oxygen. We further showed that by replenishing NO bioactivity, the defect was corrected. We have now also found that prolonged storage leads to a defect in the regeneration of S-nitroso-hemoglobion (i.e. evident with older blood), which is at least partly reversible. This novel mechanism for the loss of physiological activity in banked blood and, more importantly, a putative intervention for its correction, raise the possibility that restoration of NO bioactivity prior to administration of packed RBCs may significantly ameliorate transfusion-associated ischemic morbidity. Our findings have led to the present grant application in which we will test the following hypothesis: Renitrosylation to increase S-nitroso-hemoglobin content restores the hypoxic-vasodilatory activity of stored RBCs to improve tissue oxygen delivery and physiologic status during transfusion. Research Objectives: 1. To optimize and validate in vitro methods of large-scale renitrosylation that restore hypoxic- vasodliatory activity to banked RBCs independent of blood group and across storage conditions; and 2. To conduct focused in vivo assessments to demonstrate the benefits of pre-transfusion renitrosylation on blood flow and local oxygen delivery. Through the proposed series of bench top, pre-clinical, and clinical experiments detailed herein, we will establish large-scale methodology to renitrosylate stored blood and thoroughly assess the physiological benefits. We anticipate that the information generated from these studies may affect fundamental changes in clinical care. Restoration of NO bioactivity and oxygen delivery capabilities of stored RBCs will result in blood transfusion achieving its clinical purpose: vasodilation in the micro-circulation to maintain or enhance end- organ oxygen delivery in the anemic patient. Renitrosylation would be a novel therapeutic intervention, extremely easy to implement, that could yield significant clinical benefits and economic savings. PUBLIC HEALTH RELEVANCE: Blood transfusion is among the most commonly performed medical procedures: each year approximately 5 million Americans receive 14 million units of packed red blood cells (RBCs) to treat anemia resulting from a variety of acute causes and chronic disease states. However, it is now recognized that the administration of packed RBCs may not only fail to improve oxygen delivery but may actually worsen ischemia. Based on the proposition that an impairment in the vasodilatory ability of RBCs (resulting from storage-related depletion of nitric oxide bioactivity) contributes substantially to transfusion-related morbidity, we propose to generate methods for the restoration of RBC nitric oxide bioactivity in clinical settings, and to determine whether restoration of RBC vasodilation ameliorates the deleterious effects of transfusion.