POLYMER-COATED RED BLOOD CELL FOR SICKLE CELL DISEASE

描述：(研究人员摘要)虽然红细胞(RBC) 输血是处理急性并发症的重要组成部分。 镰状细胞病(SCD)，最近的“停止”研究表明 慢性输血可以预防SCD高危儿童中风， 在SCD中输血有相关的问题：1)高同种异体免疫率(上升 到30%)和铁的积累；2)输血后的限制 将红细胞压积降至35%以下，以避免血液高粘度，这可能会 引发血管闭塞事件。然而，我们最近开发了一种 有可能缓解这些问题的技术：共价键 将聚乙二醇膜或相关聚合物涂到红细胞上 浮出水面。到目前为止的结果表明，由于涂层，红细胞表面 不能被抗体访问(即，RBC血型抗原被“遮盖”) 而RBC相互作用，如RBC聚集，被最小化；后一种效果 结果极大地降低了低切血液粘度，即使当红细胞压积 SS血随包被红细胞的增加而增加。 本研究计划的最终目标是开发安全和 有效的红细胞聚合物包被方法，实现抗原掩蔽和 降低黏度，对镰状细胞有治疗作用 疾病研究对象。具体目标包括：1)优化聚合物涂层 通过评估线形、支化、星形和树枝状聚乙二醇分子的技术 以及各种成键化学和交联策略；2)评价 从红细胞形态来看，聚合物包被红细胞的功能状态， 流变性(即变形性)、膜运输和氧气 结合，鉴定受影响的膜蛋白(例如，C-14标记的 Pegs)，包被细胞的储存能力，以及在小鼠和 兔系统；3)评价聚合物包被红细胞作为治疗剂在 用体外流变学研究M和SS RBC混合物在不同温度下的SCD 血球压积和氧分压，以及通过大鼠体内血流研究 肠系膜和猫骨骼肌制剂.4)聚合物的评价 包被作为防止异体免疫和/或保护输血红细胞的一种手段 在同种异体免疫的受试者中，在体外利用两者(例如抗体/补体) 结合、补体裂解、单核细胞单层分析)和体内方法 (如同种异体免疫兔模型、异种输血)方法。一个互动的 提出了实现这些目标的方法；它们的成功实现应该产生 SCD的重要新数据和改善的医疗保健。

DESCRIPTION: (Investigator's abstract) Although red blood cell (RBC) transfusion is an essential component in the management of acute complications of sickle cell disease (SCD), and the recent "STOP" study has demonstrated that chronic blood transfusion can prevent stroke in high-risk SCD children, transfusion in SCD has associated problems: 1) high alloimmunization rates (up to 30 percent) and iron accumulation; 2) limitation of post-transfusion hematocrit to less than 35 percent to avoid blood hyperviscosity which may precipitate a vaso-occlusive event. However, we have recently developed a technique which has the potential to mitigate these problems: covalent bonding of a thin coating of polyethylene glycol (PEG) or related polymers to the RBC surface. Results to date indicate that consequent to coating, the RBC surface is inaccessible to antibodies (i.e., the RBC blood group antigens are "masked") and RBC interactions, such as RBC aggregation, are minimized; the latter effect results in greatly reduced low-shear blood viscosity even when the hematocrit of SS blood is increased with coated RBC. The ultimate objective of this Research Program is the development of safe and effective RBC polymer coating methods which achieve antigen masking and viscosity reduction and which offer therapeutic benefits for sickle cell disease subjects. Specific aims include: 1) optimizing polymer coating techniques via evaluating linear, branched, star and dendrimer PEG molecules and various bonding chemistries and crosslinking strategies; 2) evaluation of the functional status of polymer-coated RBC in terms of RBC morphology, rheological behavior (i.e., deformability), membrane transport and oxygen binding, identification of membrane proteins affected (e.g., C-14 labeled PEGs), the storage ability of coated-cells, and in vivo survival in mice and rabbit systems; 3) evaluation of polymer-coated RBC as therapeutic agents in SCD via in vitro rheologic studies of M and SS RBC mixtures at various hematocrits and oxygen tensions, and via in vivo flow studies using rat mesocecum and cat skeletal muscle preparations; 4) evaluation of polymer coating as a means to prevent alloimmunization and/or to protect transfused RBC in alloimmunized subjects by utilizing both in vitro (e.g., antibody/complement binding, complement lysis, monocyte monolayer assay) and in vivo approaches (e.g., alloimmunized rabbit model, xenotransfusions) methods. An interactive approach to these aims is proposed; their successful achievement should yield important new data and improved health care in SCD.