CELL AND PROTEIN REACTIONS WITH FOREIGN MATERIALS

缺乏对血液与高分子生物材料反应机制的了解仍然是设计用于与血液接触的更好材料的障碍。我们关于这些机制的假设可以概括如下：特定的材料变量导致吸附蛋白层的变化，而这些变化负责血小板粘附和/或活化的变化。对于某些聚氨酯（peu），重要的特定材料变量被认为是烷基链长度和密度以及FC peu中氟碳（FC）基团的表面富集程度。系统研究这些材料变量对蛋白质和血小板相互作用的影响将有助于更好地理解血液与聚合物的反应性。具体目的如下：1。吸附的粘附蛋白纤维蛋白原、血管性血友病因子、纤维连接蛋白和玻璃体连接蛋白在引起血小板活化中的作用将通过血浆中选择性缺乏该蛋白和一系列与血小板相互作用的peu来确定。血小板活化的特征将是测量粘附血小板参与血小板-血小板聚集形成的能力，血小板向促凝状态的转化，以及在流动条件下血小板粘附时细胞内钙动员的原位测量。还将进行缺陷因子修复效果的剂量反应研究。2. 为了验证生物材料的血小板活化是每种类型底物上吸附纤维蛋白原的数量和状态的函数这一假设，将流动悬浮液沉积的血小板活化与一系列聚氨酯上纤维蛋白原的总量和血小板可识别分数进行比较。吸附纤维蛋白原的血小板可识别性将使用单克隆抗体结合每个假定的纤维蛋白原血小板结合域来表征。3. 一系列特殊制造的聚氨酯（PEUs），其化学成分的变化会影响粘附蛋白和白蛋白的吸附和生物活性，将用于测试我们的机械材料假设。将使用侧链长度、链密度和链类型（CH2或CF2）不同的peu。尽管存在相对大量的吸附纤维蛋白原，但peu表现出低血小板粘附性，这将得到更深入的研究，因为我们相信，了解纤维蛋白原的生物活性被这些材料改变的机制，有助于改进生物材料的智能设计。参考材料为Biospan和NIH PE和PDMS。

The lack of knowledge of the mechanisms underlying the reactions of blood with polymeric biomaterials continues to be an obstacle to the design of better materials for use in contact with blood. Our hypothesis about these mechanisms can be stated generally as follows: a specific materials variable causes changes in the adsorbed protein layer that are responsible for changes in platelet adhesion and/or activation. For certain polyurethanes (PEUs), important specific materials variables are thought to be the alkyl chain length and density and the degree of surface enrichment of the fluorocarbon (FC) groups in FC PEUs. A systematic study of the effect of these materials variables on protein and platelet interactions will contribute to better understanding of blood reactivity with polymers. The specific aims are as follows: 1. The role of the adsorbed adhesion proteins fibrinogen, von Willebrand factor, fibronectin, and vitronectin in causing platelet activation will be determined using plasmas selectively deficient in the protein and a series of PEUs interacting with platelets under flow. Platelet activation will be characterized by measuring the ability of the adherent platelets to participate in platelet-platelet aggregate formation, the conversion of the platelets to the procoagulant state, and in situ measurement of intracellular calcium mobilization in platelets adhering under flow conditions. Dose-response studies of the effect of restoration of the deficient factors will also be done. 2. To test the hypothesis that the platelet activation by biomaterials is a function of both the amount and the state of adsorbed fibrinogen on each type of substrate, the activation of platelets deposited from flowing suspensions will be compared to the total amount and platelet recognizable fraction of fibrinogen on a series of polyurethanes. The platelet recognizability of the adsorbed fibrinogen will be characterized using monoclonal antibodies that bind to each of the putative platelet binding domains of fibrinogen. 3. A series of specially made polyurethanes (PEUs) with variations in chemical composition that should affect the adsorption and the biologic activity of the adhesion proteins and albumin will be used to test our mechanistic material hypotheses. PEUs with differences in side chain length, chain density, and chain type (CH2 or CF2) will be used. PEUs exhibiting low platelet adhesion despite the presence of relatively high amounts of adsorbed fibrinogen will be studied in greater depth, since we believe understanding of the mechanisms by which fibrinogen's biological activity is altered by these materials can contribute to the intelligent design of improved biomaterials. Reference materials will be Biospan and NIH PE and PDMS.