PHYSIOLOGIC REQUIREMENTS FOR AUXILIARY LIVER HOMOTRANSPLANTATION.

Abstract

Auxiliary hepatic homotransplants were performed in dogs, the second liver being placed in the pelvis of the recipient. In each instance, the hepatic artery was revascularized from the external iliac artery. In 6 dogs, the portal vein of the homograft was anastomosed to the superior mesenteric vein and the proximal portal vein then ligated; the splanchnic blood flow was directed in a retrograde fashion through the homograft, and the dog’s own liver was left supplied solely by the hepatic artery. In another 6 dogs, a similar operation was performed and venous revascularization carried out so that the nonhepatic splanchnic flow of the recipient was shared by both the host liver and the homograft. In those animals in which the nonhepatic splanchnic flow was diverted through the auxiliary liver (group 1), the homograft retained its full size and there was marked shrinkage of the host’s own liver. Histologically, the loss of size observed in the host liver appeared to be due to centrizonal necrosis with collapse of the reticulin which was most pronounced around the central vein. In those animals in which the host liver and the homograft shared the nonhepatic splanchnic flow, there was variable shrinkage of the homograft with retention of normal size in all but 1 of the host livers. These findings appear to have defined an important physiologic requirement for auxiliary homotransplantation. Because of the apparent competition for nutritional substrate, which seems to occur in the presence of 2 livers, the homografted organ must receive its venous inflow directly from the alimentary venous return. Of even greater importance than the preservation of homograft morphologic integrity is the retention by the optimally vascularized auxiliary liver of the ability to sustain life, as demonstrated by the ultimate test imposed by removal of the host’s own liver. Despite the fact that 5 of the 6 homografts in the first group of animals had histologic evidence of cellular rejection, autologous hepatectomy in 3 of these dogs was followed by survival of 8, 28, and 49 days with total posttransplant survival of 69, 101, and 126 days. Survival in these experimental animals was greater than any previously reported hepatic homotransplantation and permitted observations of late pathologic changes. These included phlebosclerosis of the central veins, perivenous fibrosis of the portal and central veins, the development in the 2 longest survivors of fibrous bands joining some of the affected central zones one to another, and the disappearance in the same 2 dogs of the small intrahepatic bile ducts with the development of intrahepatic cholestasis. In the dogs in which serial biopsies were carried out, the findings of cellular rejection were demonstrated in every instance to diminish with the passage of time, the first histologic demonstration of the reversibility of rejection in hepatic homografts.