Ansorge W, Spindler E, Vienken J, Baurmeister U
Institute for Medical Membrane Application, Wuppertal, Germany.
Transfus Sci. 1993 Apr;14(2):199-209. doi: 10.1016/0955-3886(93)90032-P.
Plasmapheresis can be performed by centrifugation and by use of membrane technology. With the latter technique we receive a plasma which is absolutely free from platelets. This is why membranes are gaining market shares in this particular field of medical application. Today plasmapheresis membranes are mostly fabricated from synthetic polymers, such as polypropylene (e.g. PLASMAPHAN), polysulfone, polyacrylonitrile, polymethylmethacrylate, polyvinylalcohol and others, the only exception being cellulose acetate. Parameters determining the biocompatibility of plasmapheresis membranes are generation of complement C3a or C5a, hemolysis and possible thrombus formation. These parameters depend on various properties of the membrane polymer: e.g. the nature of the molecular end/side-groups, the distribution of electrical charges on the polymer surface and the different chemical structures and conformation of the polymer. In addition, membrane properties like pore distribution and geometry or the flow characteristics of a particular device-design may trigger cell activation or influence biocompatibility through the adsorption of various plasmacomponents. Most of the polymers which are used today for manufacturing plasmapheresis membranes have not been developed for this purpose. They were originally selected to be used as textile fibers. Further, no present membrane polymer has been specifically developed to achieve high biocompatibility. The membrane profile was designed in such a way that pheresis properties were met rather than optimizing biochemical blood/polymer interactions. One reason for this decision may be that the market volume of plasmapheresis technology is too small in order to justify specific and high-cost developments of polymers for this purpose. Polymer selection to achieve excellent biocompatibility profiles is determined by polymer-availability, costs, membrane-forming processes and environmental aspects related to possible pollution during the manufacturing process. The production of PLASMAPHAN by the unique Accurel-process combines several of these parameters. The main membrane production processes and especially the Accurel-process are described here. The influence of polymer-surface properties, membrane structure and module-design on the biocompatibility of plasmapheresis treatments are discussed and explained by appropriate examples.
血浆置换可通过离心法和使用膜技术来进行。采用后一种技术，我们能获得完全不含血小板的血浆。这就是膜技术在这一特定医学应用领域中市场份额不断增加的原因。如今，血浆置换膜大多由合成聚合物制成，如聚丙烯（如PLASMAPHAN）、聚砜、聚丙烯腈、聚甲基丙烯酸甲酯、聚乙烯醇等，唯一的例外是醋酸纤维素。决定血浆置换膜生物相容性的参数有补体C3a或C5a的产生、溶血以及可能的血栓形成。这些参数取决于膜聚合物的各种特性，例如分子端基/侧基的性质、聚合物表面电荷的分布以及聚合物不同的化学结构和构象。此外，膜的特性，如孔径分布和几何形状，或特定设备设计的流动特性，可能会引发细胞活化，或通过各种血浆成分的吸附影响生物相容性。如今用于制造血浆置换膜的大多数聚合物并非为此目的而开发。它们最初是被选作纺织纤维使用的。此外，目前还没有专门为实现高生物相容性而开发的膜聚合物。膜的特性设计是为了满足单采特性，而非优化血液/聚合物的生化相互作用。做出这一决定的一个原因可能是血浆置换技术的市场规模太小，不足以证明为此目的专门开发高成本聚合物的合理性。实现优异生物相容性特性的聚合物选择取决于聚合物的可得性、成本、成膜工艺以及与制造过程中可能的污染相关的环境因素。通过独特的Accurel工艺生产PLASMAPHAN综合了其中几个参数。这里描述了主要的膜生产工艺，尤其是Accurel工艺。通过适当的例子讨论并解释了聚合物表面特性、膜结构和组件设计对血浆置换治疗生物相容性 的影响。
