An Experimental Study on the Immune Responses to Regenerating Allografts in the Rat

Lee, Kyu Jin; Yoo, Chang Hyun; Heu, Bang; Yoon, Myong Hee; Lee, Chung Han; Park, Young Hun

Abstract

Partial liver transplantation from a living donor or by splitting the liver was developed to expand the donor pool. Sometimes the small-for-size liver is transplanted into larger recipient and it regenerates shortly to ideal volume for the recipient. The relationship between regeneration and rejection-intensity has not defined clearly yet. In this study the 30% partial liver of DA (Dark-Agauti) rats were transplanted heterotopically to Lewis rats by microsurgical technique. End-to-side cavocaval and end-to-end portoportal (or portomesenteric) anastomoses were performed but the artery and the bile duct were not reconstructed. In regenerating group (R), total portal blood of the recipient was diverted to the graft. In non-regenerating group (N), the superior mesenteric vein below the confluence of the splenic vein was anstomosed to the portal vein of the recipient. Both groups were treated with tacrolimus (FK-506 2 mg/kg/d) and compared with non-treated groups. Transplantations were successful with minimal operative mortality. The animals could survive for the studying period in both groups. When compared on day 3, day 5, and day 7, histologic examination revealed no significant differences of cellular infiltration between two groups. In tacrolimus-treated groups, the cellular infiltration was markedly decreased and there were no significant differences in cellular infiltration between regenerating group treated with tarcrolimus (R-F) and non-regenerating group treated with tarcrolimus (N-F). These findings suggest that immune responses to the allograft are not significantly influenced by the hepatic regeneration process in small-for-size graft. Further immunologic and molecular biologic investigation may be needed.