Gupta S, Kim S K, Vemuru R P, Aragona E, Yerneni P R, Burk R D, Rha C K
Department of Medicine, Albert Einstein College of Medicine, Bronx, NY.
Int J Artif Organs. 1993 Mar;16(3):155-63.
To evaluate systems for barrier immunoisolation of transplanted hepatocytes, we used transgenic mouse hepatocytes that secrete HBsAg. Hepatocytes were rapidly encapsulated in chitosan, a cationic polymer derived by deacetylation of chitin. Chitosan was allowed to electrostatically bond with anionic sodium alginate for creating an outer bipolymer membrane of the capsules. After encapsulation, hepatocyte viability remained unchanged for seven days in vitro with secretion of HBsAg into the culture medium throughout this period. Following intraperitoneal transplantation of encapsulated hepatocytes, HBsAg promptly appeared in blood of recipients. In congeneic recipients, serum HBsAg peaked at two weeks. Hepatocytes were present in recovered chitosan capsules and expressed HBsAg mRNA. In allogeneic recipients, however, serum HBsAg disappeared within one week and recovered chitosan capsules showed lymphomononuclear cells but not hepatocytes. Transplantation of chitosan encapsulated HbsAg secreting hepatocytes failed to induce an anti-HBs response, suggesting modulation of the host immune response. These results indicate that transplantation systems using genetically modified hepatocytes which secrete gene products in the blood of recipients should facilitate evaluation of hepatocyte encapsulation.
为了评估移植肝细胞的屏障免疫隔离系统，我们使用了分泌乙肝表面抗原（HBsAg）的转基因小鼠肝细胞。肝细胞被迅速包裹在壳聚糖中，壳聚糖是一种通过甲壳素脱乙酰化得到的阳离子聚合物。使壳聚糖与阴离子海藻酸钠静电结合，以形成胶囊的外部双聚合物膜。包裹后，肝细胞活力在体外七天内保持不变，在此期间HBsAg持续分泌到培养基中。腹腔移植包裹的肝细胞后，HBsAg迅速出现在受体的血液中。在同基因受体中，血清HBsAg在两周时达到峰值。回收的壳聚糖胶囊中存在肝细胞并表达HBsAg mRNA。然而，在异基因受体中，血清HBsAg在一周内消失，回收的壳聚糖胶囊显示有淋巴细胞单核细胞，但没有肝细胞。壳聚糖包裹的分泌HBsAg的肝细胞移植未能诱导抗HBs反应，提示宿主免疫反应受到调节。这些结果表明，使用在受体血液中分泌基因产物的基因修饰肝细胞的移植系统应有助于评估肝细胞包裹情况。
