In Vitro and in Vivo Nonthorombogenicity of Microdomain Polymers

我们已经报道了由甲基丙烯酸2-羟乙基酯（HEMA）和苯乙烯（St）组成的嵌段共聚物，具有亲疏水微域结构，表现出良好的非同源性。在这项研究中，我们讨论了表面结构和血小板活化之间的关系，用明确定义的HEMA-St嵌段共聚物。通过TEM观察、ESCA测量和接触角测量对嵌段共聚物的表面结构进行了表征。透射电镜观察到片状结构清晰，畴间距在100 ~ 600A之间。ESCA和接触角测量表明，干燥状态下St段主要集中在空气表面。聚合物浸泡在水中后，聚合物表面润湿性增加，聚合物表面接触角与PHEMA几乎相同。用柱法测定嵌段共聚物的非致气孔性。随着微畴间距的改变，血小板粘附在微畴间距160A时达到最小值。此外，为了明确膜运动对血小板在聚合物表面粘附的影响，在嵌段共聚物涂覆的玻璃珠柱中，低温和秋水珠碱处理的血小板洗脱量在秋水珠碱处理的PRP和对照PRP之间没有差异。这表明，当血小板与微结构域接触时，血小板膜运动受到抑制，血小板的主动粘附不进行。此外，在体内应用方面，还发展了以人工血管作为隐血管的植皮新技术。

We have already reported that block copolymers composed of 2-hydroxyethyl methacylate (HEMA) and styrene (St), having hydrophilic/hydrophobic microdomain structures, demonstrated excellent nonthorombogenicty. In this study, we discuss about relationship between surface structure and activation of platelets by using well-defined HEMA-St block copolymer. The surface structure of block copolymers were estimated by TEM observation, ESCA measurement and contact angle measurement. The lamella structure was clearly observed by TEM and domain spacings were from 100 to 600A. ESCA and contact angle measurement suggested that St segment was concentrated on air surface at dry state. After soaking polymers into water, however, wetability of polymer surface increase and contact angle of polymer surface show almost same value as that of PHEMA. Nonthombogenicity of block copolymers were measured by column method. As the domain spacing was altered, the platelet adhesion exhibited minimum value at 160A of micro domain spacing. Furthermore, to clarify effects of membrane movement on platelets adhesion on polymer surface, platelets were treated with low temperature and colchichine In the block copolymer coated glass bead column, the amount of eluted platelet show no deference between colchichine treated PRP and control PRP. This results indicate that platelets membrane movement was suppressed without drug when platelet contact with the micro domain structure and the active adhesion of platelet is not progressed. Further more, as in vivo application, new skin grafting technique with using artificial blood tubes as saphenous blood tubes was developed.