Competition Between Native Liver and Graft in Auxiliary Liver Transplantation in a Rat Model

Abstract

The competition between the native and the grafted liver in heterotopic auxiliary liver transplantation (HALT) with portal vein arterialization (PVA) was investigated in a rat model. The experimental groups were: HALT with flow-regulated PVA and 70% resection of a native liver and graft (n = 32; group I) versus 70% liver resection (n = 32; group II). After HALT, the weight of the native liver increased until the sixth postoperative week (431% ± 55% of the intraoperative weight), whereas, the graft weight was only 76% ± 31% of the intraoperative weight at this time. In group II, liver weight increased continuously to 529% ± 30% of the intraoperative weight after 6 weeks. On postoperative day 2, there was significantly increased proliferative hepatocellular activity in all groups. This was highest in the resected livers of group II, followed by the native livers of group I, and the grafts of group I (301 ± 126 vs 262 ± 97 vs 216 ± 31 Ki-67-positive hepatocytes/10 visual fields). However, the differences between the groups were not significant. With regard to hepatocellular apoptosis, the livers were similar among all groups and at all time points, M30-positive hepatocyte counts were ≤1/10 visual fields, which was equivalent to normal values. After HALT with flow-regulated PVA, the native liver regenerated and the graft showed atrophy, most likely caused by the lack of hepatotrophic factors in the arterialized graft portal vein blood. Regeneration of the 70% resected native liver in the presence of an arterialized heterotopic auxiliary liver graft was less pronounced than the regeneration of a 70% resected liver without HALT. Native liver regeneration seemed negatively influenced by a graft, suggesting a competition between the 2 livers.