Study on implantable artificial liver

由肝细胞和聚合物基质组成的混合型人工肝作为一种新的治疗急性肝衰竭的试验日益受到关注。高分子水凝胶对肝细胞的包封技术可防止细胞受到异体或异种免疫攻击，使其代谢功能在受体体内得以发挥。然而，尽管聚合物材料本身的物理化学性质可能为细胞封装提供信息建议，但很少有报道。本研究旨在了解适用于人工肝脏的水凝胶材料的基本知识。选择由海藻酸钠和聚丙烯胺（PAA）组成的多离子复合膜，因为在温和的条件下（例如37℃的水溶液）可以实现细胞包封。膜的含水量和机械强度或其对蛋白质、白蛋白和免疫球蛋白的渗透性与广泛用于肝细胞包膜的海藻酸盐-聚（l -赖氨酸）多离子复合物膜相似。然而，在包封前后，大鼠肝细胞的活力有很大差异。研究发现，细胞活力的降低是细胞与钙离子接触的原因，而钙离子是细胞包封的必要过程。这表明，使接触时间尽可能短的细胞封装是很重要的。

The hybrid-typed artificial liver composed of hepatocytes and polymer matrices has been increasingly notad as a new therapeutic trial of acute liver failure. The encapsulation technology of hepatocytes by polymer hydrogels will prevent the cells from allogeneically or xenogeneically immune attack, allowing their metabolic functions to perform in the recipients. However, little has been reported on the physicochemical prooerties of polymer materials themselves although they may provide an informative suggestion for cell encapsulation. The present research was undertaken to obtain basic knowledge about the hydrogel materials applicable for artificial liver. The polyion complex membrane composed of sodium alginate and poly (allyl amine) (PAA) was selected since the cell encapsulation can be achieved under mild conditions, e.g.at 37ﾟC in aqueous solution. The water content and mechanical strength of the membrane or its permeability of proeteins, albumin and immunoglobulim, were similar to those of aliginate-poly (L-lysine) polyion complex membrane which has been widely used for hepatocye encapsulation. However, a big difference in the viability of rat hepatocytes was observed before and after their encapsulation process. It was found that the viability decrease was responsible for the contact of cells with calcium ions which is a necessary process for cell encapsulation. This indicates that it is important to make the contact time as short as possible for cell encapsulation.