The Small Size Of Rats After Liver Transplantation Characteristics Of Liver Regeneration, Ischemic Preconditioning In Liver Regeneration And Related Mechanisms

PartⅠImproved methods for establishment of 30% small-for-size livertransplantation in the rat.Objective: to explore an effective and viable way to establishsmall-for-size liver transplantation model in the rat.Methods: Animals were divided into the following groups: GroupⅠ:15 rats for anatomy observation; GroupⅡ(n=28): 30% size graft livertransplantation using a median lobe graft; GroupⅢ(n=15): 30% sizegraft liver transplantation using right lobe and right mediam lobe graft;GroupⅣ(n=36): 30% size graft liver transplantation using a median lobegraft, with an improved technic of lobe resection. For GroupⅡ,Ⅲ,Ⅳ,Male Lewis rats were used as donors and recipients, the grafts wereimplanted according to Kamada's 2-cuff method. 7-day survival rate andthe technical complications including bleeding, IVC or portal veinstricture and bile leakage were compared between the groups.Results: the mean ratio of median lobe weight to the whole liverweight is 4.9% less than that of right lobe and right median lobe. 30%size liver graft could be obtained by using a donor whose weight is 10-20g less than that of a recipient when a median lobe was selected asthe graft, or 20-40g less body weight when right lobe and right medianlobe was selected as the graft. Compared to GroupⅡ,The time for liverlobe reducing in GroupⅢwas shorter, with less IVC strictures, but morebile leakages. After the improvement of lobe resection method, theincidence of IVC strictures was significantly decreased, when comparedGroupⅡwith GroupⅣ. Other complications showed no significantdifference. There were no significant differences in the 7-day survivalrate between three transplantation groups, though GroupⅣhad moresurvivors 7 days after liver transplantation.Conclusion: With improved method of lobe resection, more effectiveand viable 30% small-for-size rat liver transplantation model with amedian lobe graft can be established.PartⅡHepatic regenerative response and associated mechanisms in a ratmodel of small-for-size liver transplantation.Objective: To investigate the hepatic regeneration and associatedmechanism after small-for-size liver transplantation in the rat.Methods: We employed a rat orthotopic liver transplantation modelusing different size grafts. Animals were divided into the following groups: 100% graft size liver transplantation group (whole size group),50% graft size liver transplantation group (50% size group), 30% graftsize liver transplantation (30% group size group) and sham group.Survival rate, graft injury, hepatocellular proliferation, IL-6, activation ofStat3 and cell cycle progression were assessed.Results: The portal pressure was significantly higher in the 50% and30% size graft groups than that of the whole graft group after reperfusion.Between the two small-for-size graft groups, the 30% size graft groupshowed higher portal pressure compared with the 50% size graft group.The serum AST levels in small-for-size grafts were significantly higherthan that in the whole size grafts, but no significant difference wasobserved between the two small-for-size groups. The hepatic IL-6 levelsin the 50% size liver graft group were significantly higher than in thewhole graft group at 2 h and 48 h after reperfusion, and significantlylower than that in the 30% size grafts at 2 h and 6 h time point. Markersof regeneration downstream of IL-6, Stat3 phosphorylation, cyclin D1and PCNA expression, were also markedly increased in the small sizeliver grafts compared with the whole size ones, and appeared to positivelycorrelate with the early portal pressure and the subsequent hepaticparenchymal injury. 7-day survival rate was also reduced in the two smallsize groups, but it did not reach a significant difference.Conclusion: The vigorous hepatic regenerative response in Small-for-size liver grafts may associate with highly activated IL-6/Stat3signaling, which may due to the smaller graft size, higher portal pressure,and subsequent hepatic parenchymal injury.PartⅢImpaired hepatic regeneration by ischemic preconditioning in a ratmodel of small-for-size liver transplantationObjective: Graft size is a major risk factor in adult-to-adult livingdonor liver transplantation (ALDLT). Rapid regeneration is clearlyrequired after ALDLT. Ischemic preconditioning (IPC) has been provenan effective strategy to reduce hepatic ischemia-reperfusion injury andenhance liver regeneration. This study was designed to evaluate theeffects of IPC on liver regeneration in small-for-size liver grafts.Methods: We employed a rat orthotopic liver transplantation modelusing a small-for-size (30%) graft without (control) or with IPC (10minutes of ischemia followed by 15 minutes of reperfusion). Survival rate,graft injury, hepatocellular proliferation, TNF-α, IL-6, activation of Stat3and cell cycle progression were assessed.Results: IPC significantly enhanced the graft injury and reduced thehepatic regeneration in small-for-size liver grafts. 7-day survival rate wasalso reduced by IPC but it did not reach a significant difference. IPC did not modify TNF-αlevel, but significantly decreased the elevation of IL-6after reperfusion. Correlated with these changes, cyclin E and cyclin D1were down-regulated and, PCNA-positive nuclei were significantlydecreased in the IPC grafts. These results did not appear consistent withthe activation of Stat3, as P-Stat3 displayed stronger and prolongedpattern of activation in the IPC group.Conclusion: IPC may impair liver regeneration in small-for-size livergrafts by decreasing IL-6 and blunting the cell cycle progression, and atleast partly independent of Stat3.