Engineered Protein Oxygen Carriers: a novel blood substitute for trauma care

迫切需要人工氧(O2)载体作为献血的替代品 产品。对于危及生命的出血患者，输血是目前最有效的治疗方法。 美国近25%的血液中心常年供不应求。此外，食品的易腐烂性 血液产品与血液的免疫反应潜力相结合，使得输血 产品在非医院环境中存在很大问题。及时获得血液的问题尤其突出 在艰苦的环境中(如战场、农村地点)具有挑战性，在那里需要长时间的运输才能最终确定 可能需要小心。不幸的是，未能在黄金时间内输血会增加 临床结果差的风险，包括死亡。 拟议的研究旨在利用从头设计的人造血红素蛋白的最新进展。 为了克服早期基于天然血红蛋白的紧急血液替代品的设计局限性。 工程蛋白O2载体(EPOCs)天生比血红蛋白更具适应性，从而 气态配基亲和力的直接控制。EPOCs还提供对热稳定性(高压灭菌性)的控制， 每种蛋白质的相对分子质量和净电荷(血液清除率)、氧结合部位密度 (运输能力)以及其他所需的物理特性。重要的是，我们的初步结果是 啮齿动物失血性休克模型显示，与对照组相比，EPOCs可增强组织氧输送 标准乳酸林吉斯复苏。 这项提议将在三个与 O2结合EpoC框架中的血红素以产生大量EpoC变异体文库。这些变种将 快速筛选出三个高、中、低氧亲和力的EPOC，同时保持紧密 亚铁血红素结合。他们还将被选为低一氧化氮结合力的人，以避免潜在的适得其反 血管收缩。用EPOCs替代失血大鼠的初步筛选试验 将确定这三种氧气亲和力中是否有哪一种比我们目前流通的EPOC表现得更好。 领先的EPOC候选者随后将在更大的老鼠试验中进行药物安全性测试，血液 稳定性和清除性，以及潜在的免疫原性或毒性。另一系列啮齿动物试验将 在两种休克模型中量化EPOC在治疗严重失血性休克中的效率 自由出血性肝撕裂伤休克模型。 通过确定流通中的EPOCs的最佳性能，并建立其安全性和 功效，我们将提供必要的手段，以建立一个安全，有效和持久的氧气载体 最终目标是扩大国家获得紧急“血液”产品的机会，并使 输血医学。

There is a pressing need for artificial oxygen (O2) carriers as an alternative to donated blood/blood products. For victims of life-threatening hemorrhage, transfusion is the most effective treatment, yet nearly 25% of the nation's blood centers are perennially in short supply. Additionally, the perishability of blood products coupled with blood's potential for immunologic reactions, makes the transfusion of blood products highly problematic in non-hospital settings. The issue of timely access to blood is particularly challenging in austere environments (i.e. battle field, rural site) where lengthy transports to definitive care may be required. Unfortunately, failure to transfuse blood within the “golden hour” increases the risk of poor clinical outcomes including death. The proposed studies aim to use modern advances in de novo designed artificial heme proteins to over come the design limitations of earlier emergency blood substitutes based on natural hemoglobin.. Engineered Protein O2 Carriers (EPOCs) are inherently more adaptable than hemoglobins, allowing direct control of gaseous ligand affinity. EPOCs also offer control over thermal stability (autoclavability), molecular weight and net charge (blood clearance rates), density of O2 binding sites per protein (transport capacity) as well as other desirable physical properties. Importantly, our preliminary results in a rodent hemorrhagic shock model suggest that EPOCs enhance tissue oxygen deliver compared to standard lactated Ringers resuscitation. This proposal will use diverse amino acid substitutions at three specific sites in contact with the O2 binding hemes in the EPOC frame to generate a large library of EPOC variants. These variants will be rapidly screened to select three EPOCs with high, medium, and low O2 affinity, while maintaining tight heme binding. They will also be selected for low nitric oxide binding to avoid potential counterproductive vascular constriction. An initial screening trial in rats using EPOCs to replace blood lost to hemorrhage will identify if any of the three classes of O2 affinities performs better than our current EPOC in circulation. The leading EPOC candidate will then be tested in larger rat trials for pharmacological safety, blood stability and clearance, and potential immunogenicity or toxicity. Another series of rodent trials will quantitate EPOC efficiency at treating severe hemorrhagic shock, in both a shock model with controlled bleeding and a freely hemorrhaging liver laceration shock model. By establishing the best properties for EPOCs in circulation and establishing their safety and efficacy, we will provide the means necessary to build a safe, effective and durable O2 carrier with the ultimate goal of expanding the nation's access to emergency “blood” products and revolutionizing transfusion medicine.