The Study Of The Protective Effect Of Normothermic Machine Perfusion On Pig Split Liver Transplantation

Objective: Liver transplantation has become the only treatment modality for patients with end-stage liver diseases. Unfortunately, available donor supply could not keep up with the growing number of recipients. To overcome this growing imbalance,transplant centers developed strategies to expand the organ donor pool. These strategies have included living donor liver transplantation(LDLT), split-liver transplantation(SLT), extended criteria donor livers such as elderly livers, and donation after cardiac death donors. Living donor liver transplant surgery has higher complication rates, both biliary and vascular than SLT. Another advantage to SLT is that it eliminates potential donor complication and death associated with LDLT. SLT include ex-vivo splitting of the liver and in-situ splitting of the liver.The most grafts in china are DCD grafts, splitting of the liver under the cold preservation has lead to a long time of cold preservation,and a severe outcome of ischemia-reperfusion injury. Research have showed that the time of liver cold ischemia severely affects the prognosis of liver transplantation, and directly related to the increasing incidence of PNF and complication of biliary. NMP could maintain the physiological function and metabolism of the cells mainly through the continuous supply of oxygen, nutrients in vitro. we subject to establish a simple, stable, practical NMP system, and to investigate the protective effect of NMP on porcine SLT.Methods: 1. The establishment and evaluation of NMP preservation system in the process of SLT. NMP system was established with peristaltic pump, oxygenator, water bath box, filter plug device, flow pressure sensor, and etc. To confirm the stability and practicability of the NMP device in the process of splitting donor livers, we investigate the pressure and flow of the portal vein and hepatic artery, temperature, blood gas analysis, ALT, AST, LDH, ALP in the perfusion fluid, and the bile production, pathological changes of the ex vivo splitting donor livers under NMP preservation derived from 4 Bama miniature pigs. 2. The establishment of split liver transplantation model in pigs without veno-venous bypass : The model of split liver transplantation in pigs without veno-venous bypass was developed using 20 healthy Bama miniature pigs after splitting in the process of cold preservation. The intraoperative hemodynamic changes, biochemical markers(ALT, AST, TBIL, DBIL) in the following 5 days after the operation, the incidence of postoperative complications were monitored to verify the stability of the model and master the operation skills of the split liver transplantation. 3. The protective effect of NMP on porcine SLT: 24 Bama miniature donor pigs were randomly allocated to two groups. In the group A, donor livers were split in the process of cold preservation. In the group B, donor livers were split in the process of NMP preservation. SLT without by-pass was performed in both groups. The serum biochemical markers, the histopathological changes of the donor livers were compared between two groups.Results: 1. The NMP equipment was successfully constructed. During the course of the pig donor livers splitting under NMP preservation, the blood flow and pressure of hepatic artery and portal vein, the temperature were stable. The production of bile secretion decreased gradually, the levels of ALT, LDH slightly elevated, the levels of ALP were stable with the progress of liver splitting, the levels of AST were close to the beginning of NMP preservation, and then elevated with the progress of liver splitting. The pathological examination demonstrated that the histological structure of the donor livers was normal after splitting donor livers under NMP preservation. 2. The 5d survival rate of the recipient pigs was 50%, and no surgical complications were occurred after early period of technical training. 5 recipient pigs were died. 2 cases of them died of intraperitoneal hemorrhage, the remaining 3 cases died of hypovolemic shock caused by much more peritoneal exudate. Obvious decreasing of the MAP and increasing of the heart rate was observed during the anhepatic phase. Significant depressing of the pH and BE level in arterial blood was found after the reperfusion of donor livers. The levels of ALT, AST were stable, the levels of TBIL,DBIL slightly elevated after the operation, reaching a peak on the second day and then declined slightly. 3. The amount of bleeding during the operation was obviously less in group A than in group B(p<0.05), the levels of ALT, AST in group A was lower than those in group B after 3 days of postoperative(p<0.05), the levels of LDH in group A was lower than those in group B(p<0.05) after 2 days of postoperative. The pathological examination of the donor liver demonstrated that the injury of the hepatocytes in group A was slighter than that in group B after splitting of preservation or reperfusion.Conclusion: 1. The NMP preservation system established in the study was stable, there was no obvious injury to the liver tissue in the progress of liver splitting under the NMP preservation. 2. The model of pig SLT without veno-venous bypass was successfully developed, operation skills was improved through training repeatedly, especially in stanch bleeding of liver splitting section. The size of graft required for successful SLT is(40.50±4.83)% of the expected liver weight for the recipient or(0.95±0.16)% of the body weight for the recipient. 3. The successful model of pig SLT proved NMP system has a protective effect on pig SLT.