| Background and objective Auxiliary liver transplantation possesses promising prospect as a treatment of acute liver failure. In addition, this method is able to retain the opportunity of liver regeneration, probably avoid long-term use of immunosuppressants and possess other advantages. However, for both auxiliary and host livers, how to allocate the blood flow in portal vein system of receptors plays a vital role in liver outcomes and patients'prognosis. In this study, the pathway of intestinal endotoxin entering blood in SD rats with acute liver failure after partial hepatectomy was observed. Also, this study is designed to assess the effect of mesocaval shunt on the arterialization of autologous semi-hepatic portal vein, and validate the plausibility of applying auxiliary liver transplantation with mesenteric venous blood supply into treatment of acute liver failure.Methods1. The rats'models with acute liver failure induced by 90% partial hepatectomy were established. Those rats receiving 70% partial hepatectomy and sham operation were used as controls. Following operation, survival conditions of tested rats were observed. Liver function, variations in blood ammonia and TNF- levels were detected at different time points (6h, 12h, 18h, 24h, and 7d postoperatively), respectively. Endotoxin levels in different types of blood (mesenteric venous blood, splenic venous blood, and peripheral blood) were measured accordingly. Pathological changes in liver and intestinal tract were observed.2. The rats'models with arterialization of semi-hepatic portal vein were built. Those rats with arterialization of total liver portal vein, 70% partial hepatectomy, and sham operation were designed as controls. Liver function, blood ammonia changes were measured at various time points postoperatively (3d, 7d, 2w), respectively. Different liver lobes were weighted. Liver pathological status was observed under transmission electron microscopy. The expressions of Ki67 and Caspase-3 in liver cells were detected by immunohistological staining method.3. The rats'models receiving (95% partial hepatectomy+ arterialization of semi-hepatic portal vein+ mesocaval shunt) (95%PH+HPVA+MCS) were established. Those rats undergoing 95%PH, 95%PH+MCS, and simulating 95%PH+HPVA were regarded as controls. Following operation, survival conditions of tested rats were observed. Liver function, variations in blood ammonia and endotoxin levels were detected at different time points (24h, 48h, 72h, and 7d postoperatively), respectively. Different liver lobes were weighted. Liver pathological status was observed under transmission electron microscopy. The expression of Ki67 in liver cells was detected by immunohistological staining method.4. The auxiliary liver transplantation-rats'models with mesenteric venous blood supply were established. Those counterparts undergoing 90% PH were utilized as controls. Following operation, survival conditions of tested rats were observed. The weight variations and pathological prognosis in host and auxiliary livers were noted.5 Statistical analysis: SPSS 16.0 software was employed to perform one-way ANOVA, rank sum test, and survival analysis, etc. P<0.05 was considered to be significant difference.Results1. The rats receiving 90% PH died 28 to 51 h following operation, whose survival condition was significantly lower than those in sham operation group and 70% PH group (u = 12.746 P= 0.002). ALT, AST, ALP, and blood ammonia levels all gradually increased in 90% PH group, whereas albumin concentration decreased gradually. Endotoxin level in mesenteric venous blood was markedly higher compared with those in splenic venous blood and peripheral blood 24 h postoperatively in 70% PH group, and 6, 12 h postoperatively in 90% PH group. TNF- level in serum escalated as time proceeded in 90% PH group. Endotoxin levels in mesenteric vein, splenic vein, and peripheral blood all significantly correlated with TNF- level detected in peripheral blood (P<0.001), among which the highest correlation efficient of 0.993 was noted between endotoxin levels in mesenteric vein and TNF- level in peripheral blood. In 90% PH group, liver tissue injury can be seen. The structure of liver lobe was blurry. Blood sinus expanded in a diffusing or focal pattern. Liver cellular degeneration and necrosis occurred. Inflammatory cells infiltrated into portal venous area. The lamina propria in ileum mucosa became attenuated. Partial epithelial cells degenerated and disintegrated. The villus edema was found, which became thickened and shorter, and was distributed in disorder. Lymphocytosis was noted.2. Excellent postoperative survival condition was observed in rates receiving arterialization of semi-hepatic portal vein, arterialization of whole liver portal vein, and sham operation. Blood ammonia level in arterialization of whole liver portal vein group was significantly higher compared with those in other two surgical groups 7d and 2w postoperatively. After arterialization of whole liver portal vein operation, each liver lobe weight/rats'weight showed no evident changes compared to those in sham operation group. After arterialization of semi-hepatic portal vein operation, total liver weight/rats'weight presented no significant difference from those in sham operation group at each time points (3d, 7d, and 2w following operation), respectively. The ratio of right liver weight/rats'weight was increased gradually as time proceeded, while left plus middle liver weight/rats'weight steadily decreased (all P<0.05). Following arterialization of semi-hepatic portal vein operation, more liver cells apoptosis were found and steadily aggravated as time developed. In arterialization of semi-hepatic portal vein group, the positive rates of Ki67 expression in right lobe cells were markedly higher than those in any other group (all P<0.05) 3d and 7d following operation, respectively. At each postoperative time point (3d, 7d, and 2w), the positive rate of Caspase-3 expression of left lobe cells was significantly higher than that in any other group (all P<0.05),and the difference reached maximal level on 7th day postoperatively.3. The survival time in (95%PH+ HPVA+MCS) group was significantly longer than that in (95%PH +HPVA) group. However, the survival time in (95%PH +HPVA) group was markedly longer compared with those in 95% PH group and (95%PH +MCS) group. Compared with (95%PH+HPVA) group, 48h and 72h postoperatively, ALT, AST, ALP, TB and blood ammonia levels were significantly lower while ALB was markedly higher in (95%PH+ HPVA+MCS) group. In (95%PH+HPVA) group, ALT, AST, ALP, TB and blood ammonia levels steadily increased, whereas ALB level gradually dropped. In (95%PH+ HPVA+MCS) group, ALT, AST, ALP, TB and blood ammonia levels steadily decreased, whereas ALB level gradually climbed. Comparing endotoxin level between portal venous and peripheral blood, endotoxin level in portal vein was markedly higher than that in peripheral blood only in (95%PH+HPVA) group 24h postoperatively. In other groups, no significant difference was noted regarding endotoxin levels between portal venous and peripheral blood. The endotoxin levels obtained in portal vein and peripheral blood in 95%PH and (95%PH+MCS) groups were significantly higher than those in (95%PH+HPVA) and (95%PH+HPVA+MCS) groups. However, the endotoxin level in (95%PH+HPVA) group was markedly higher than that in (95%PH+HPVA+MCS) group. The endotoxin levels contained in portal vein and peripheral blood in (95%PH+HPVA) steadily enhanced as time proceeded. The endotoxin levels in (95%PH+HPVA+MCS) group basically stabilized after operation. In (95%PH+ HPVA+MCS) group, right lobe weight/rats'weight steadily increased as time developed. Right lobe weight/ rats'weight in (95%PH+ HPVA+MCS) group was significantly higher than those in (95%PH+HPVA) group 48h and 72h post operation, respectively. No significant difference was noted among (left + middle) lobe weight/ rats'weight calculated on the first 3 days postoperatively (24h, 48h, and 72h). But (left + middle) lobe weight/ rats'weight ratio significantly decreased 7d following operation. In 95%PH+HPVA+MCS) group, the positive rate of Ki67 expression in right lobe cells was markedly higher compared with those in (95%PH+HPVA) group at each time point assigned (24h, 48h, and 72h postoperatively). Twenty-four hours following operation, the positive rate of Ki67 expression in (left + middle) lobe cells in (95%PH+HPVA+MCS) group was markedly higher than that in (95%PH+HPVA) group 24h post operation.4. In 90% PH group, 10 SD rats died during 25 to 46 h postoperatively. In (90%PH+ALT-MVBS) group, 2 of 10 rats died 2w following operation, and survival rate was 8/10. The survival condition in (90%PH+ALT-MVBS) group was significantly higher than that in 90%PH group (u=15.752, P<0.001). In (90%PH+ALT-MVBS) group, 3d after operation, ALT, AST, and ALP levels were markedly higher compared with those in sham group, 7d group, and 2w group (all P<0.05). However, ALB level was significantly lower than that in any other group (P<0.05). There was no statistical significance among various groups in terms of TB and blood ammonia levels. In (90%PH+ALT-MVBS) group, the ratio of host liver weight/rats'weight gradually increased, whereas auxiliary liver weight/rats'weight ratio steadily decreased. Conclusion1. Acute liver failure can be successfully induced by 90% partial hepatectomy. The models chosen in this study are stable and easy to operate, which serves as a desirable rats model for acute liver failure. Progressively aggravated endotoxemia acts as an important link of the process of inducing acute liver failure by 90% partial hepatectomy. During the induction process, mesenteric venous reflux functions as one of major pathways for enterogenous endotoxin entering blood circulation.2. The livers receiving arterialization of semi-hepatic portal vein have no access to liver nutritional factors in portal vein system. The livers undergoing arterialization of liver portal vein steadily shrank postoperatively, while those livers accessible to portal venous blood supply gradually proliferate. These experimental results support the hypothesis that liver nutritional factors exist in portal vein system.3. During the development of inducing acute liver failure by partial hepatectomy, enterogenous endotoxin accumulated in mesenteric system may be a factor aggravating state of illness and causing death. In the treatment of acute liver failure induced by partial hepatectomy, arterialization of liver portal vein combined with mesocaval shunt can yield excellent survival rate.4. The heterotypic auxiliary liver transplantation models with mesenteric venous blood supply are easy to establish with a high success rate. In addition, acute liver failure induced by 90% partial hepatectomy can be successfully reversed. Host liver is able to regenerate well. Auxiliary liver still maintain excellent structure and morphology 2w postoperatively.
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