The Liver Transplantation Model In Rats With Marginal Volume And Control Portal Pressure On The Donor Liver Protective Effect

Objective Our aim in this part is through different kind of reduced size liver transplantation in rats,to establish an animal model of orthotopic liver transplantation using marginal size graft.And it provides a suitable and stable animal model of marginal size graft liver transplantation model for studying small for size syndrome after liver transplantation.It is the base to understand the mechanism of grafts injury in small-for-size syndrome.Methods Male Sprague-Dawley rats,weighting from 190 to 250 grams,weight differs by 20 to 30 grams,the little one were chosen as donors.The experiment compared 4 groups of liver transplantation with designated ratios of donor and recipient liver weight.group A,whole graft group(n=24);group B,50%ratio liver transplantation(The median lobe and right lobe of the liver was selected to be the graft,n=24);group C, 30%ratio liver transplantation(The median lobe of the liver was selected to be the graft,n=24);group D,less than 30%ratio liver transplantation (The median lobe and left lobe of the liver was reduced,and remained lobe was selected to the graft,n=24).A rat model of nonarterialized orthotopic liver transplantation without veno-venous bypass was used.In the small-for-size graft group,the lobe ligation technique was used to reduce the graft size on the backtable.Operation parameters,portal pressure,liver function and survival rate were observed and analyzed in all group.Results One week survival rate of the group A,B,C and D was 100%,83.3%,16.7%and 0 respectively.The portal pressures of the whole graft group were relative stable after reperfusion.But there was a significant increase in portal pressure in the reduce size graft group at 5 and 15 minutes after reperfusion compared with that before transplantation.This increase in portal pressure reached a peak at 15 minutes(increased by 65%～82%,group C,16.47cmH₂O vs 9.97 cmH₂O,P＜0.05;group D,18.25 cmH₂O vs 10.05 cmH₂O,P＜0.05)and gradually subsided after 30 minutes of reperfusion.Each group ALT levels increased significantly at 24 hours after liver transplantation,the four groups in Group D to the highest level,C group followed,and then B group,Group A lowest.Each group of differences have statistics significance,P＜0.001.Conclusions1.The minimum safely graft volume in rat liver transplantation is 50%, The marginal size graft volume ratio is between30～35%,and the ratio less than 30%should be considered as extra-small-for-size liver transplantation in the rat.2.To establish an animal model of orthotopic liver transplantation using marginal size graft in rat,we can use weigh from 190 to 250 grams rat, and weight differs by 20 to 30 grams,the little one were chosen as donors.The median lobe of the liver was selected to be the graft and can let the ratio of the graft between 30～35%.3.In a rat liver transplantation model using marginal size graft,the portal pressure changes in marginal size grafts are transient.Progressive damage of the graft may result from microcirculatory failure due to irreversible endothelial injury after reperfusion. Objective The aim of this study is to investigate the protective effect of terlipressin on decrease portal pressure in a rat liver transplantation model using marginal size graft and to clarify the possible mechanism of the marginal size graft injure after acute phase of reperfusion.Methods The previously described rat model of nonarterialized liver transplantation using marginal size grafts was used.Survival recipients were divided into two groups:experimental group and control group.In experimental group,50ug/kg rat body weight of terlipressin was infused via the femoral vein before portal vein clamping and immediately after reperfusion,respectively.In control group,same vehicle of saline was administered as control.Six rats in each group were sacrificed randomly at 6hr and 24hr after reperfusion respectively.The survival rate of animals and portal pressure was investigated.The animals in experimental group and control group were sacrificed and blood samples were collected for endotoxin level and liver function measurement.Partly Liver specimens were morphologically examined under light microscopy and electron microscopy.The content of SOD and MDA in liver tissue was measured. The mRNA expression of TNF-αwas detected using real-time PCR (RT-PCR).6 rats at each time pointing each group were studied.Results1.Survival study showed the 7-day survival rate of 66.7%in terlipressin treatment group and 25.0%in control group,respectively.The significant difference was investigated between two groups(P＜0.05).2.There was a significant increase in portal pressure in both groups at 5 and 15 minutes after reperfusion compared with that before transplantation.This increase in portal pressure reached a peak at 15 minutes(increased by 59%in control group and 33%in experimental group,13.52 vs 16.07,P=0.003)and gradually subsided after 30 minutes of reperfusion.The portal pressures of the experimental group were relative stable after reperfusion.3.Biochemical data showed that the level of hepatic enzymes(ALT and AST)reached the peak at 6 hours after reperfusion in each group.At 6 and 24 hours after reperfusion,the levels of ALT and AST in experimental group were significantly lower than those in control group (P＜0.05).4.Morphological investigations using light microscopy and electron microscopy showed the well-preserved morphology and ultrastructural integrity in experimental group,5.RT-PCR results showed that the intragraft expression of TNF-αmRNA in terlipressin treatment group was down-regulated at each time point after reperfusion.6.The level of plasma endotoxin after reperfusion was increasing by time. At 6 and 24 hours after reperfusion the levels of plasma endotoxin in experimental group were significantly lower than those in control group respectively(P＜0.05).7.The content of MDA after reperfusion was increased by time,inversely; the level of SOD was decreasing by time.But There was no statistical significance(P＞0.05)Conclusions1.In the rat liver transplantation model using marginal size graft,the distinct hepatic injury of marginal size liver grafts was characterized by irreversible endothelial injury that resulted from severe hepatic sinusoid shear stress induced by transient significant increase portal hypertension at the early phase after reperfusion.2.Terlipressin can rescue marginal size graft from acute phase injury after reperfusion by attenuated the acute phase shear stress that resulted from transient portal hypertension. Objective The aim of this study is to evaluate the effects of control portal pressure on liver regeneration in marginal size liver transplantation in rat.Methods The previously described rat model of nonarterialized liver transplantation using marginal size grafts was used.Survival recipients were divided into two groups:experimental group and control group.In experimental group,50ug/kg rat body weight of terlipressin was infused via the femoral vein before portal vein clamping and immediately after reperfusion,respectively.In control group,same vehicle of saline was administered as control.Six rats in each group were sacrificed randomly at 1,2,4 and 7 days after transplantation respectively.Each graft was removed and weighed.The regenerative response of liver graft was evaluated by Flow Cytometry.Expression of Ki-67 antigen in hepatocyte was measured with immunohistochemistry assay. Results1.On 1 and 2 days after transplantation the wet weight of graft and liver regeneration rate in experimental group was significantly larger than that of the grafts in control group.But on 4 and 7 days after transplantation there are no different in both groups.2.The results of the hepatocyte proliferate index and Ki-67 labeling index of the graft show,that the hepatocyte proliferate index and Ki-67 labeling index of the graft reach a peak at 2 day after transplantation in both group.The hepatocyte proliferate index and Ki-67 labeling index of the graft of experiment group was higher than that in control group on 1 day and 2 day after transplantation.While there was no significant difference between two group on 4 day and 7 day.ConclusionsTerlipressin have no directly effect on hepatocyte regeneration in rat liver transplantation model using marginal size graft.It only by reducing portal pressure,protect the marginal size graft and indirectly for the maintenance the liver regeneration smoothly.