Orthotopic liver retransplantation in rats

Metformin Preconditioning Improves Hepatobiliary Function and Reduces Injury in a Rat Model of Normothermic Machine Perfusion and Orthotopic Transplantation

Background.

Preconditioning of donor livers before organ retrieval may improve organ quality after transplantation. We investigated whether preconditioning with metformin reduces preservation injury and improves hepatobiliary function in rat donor livers during ex situ normothermic machine perfusion (NMP) and after orthotopic liver transplantation.

Methods.

Lewis rats were administered metformin via oral gavage, after which a donor hepatectomy was performed followed by a standardized cold storage period of 4 hours. Graft assessment was performed using NMP via double perfusion of the hepatic artery and portal vein. In an additional experiment, rat donor livers preconditioned with metformin were stored on ice for 4 hours and transplanted to confirm postoperative liver function and survival. Data were analyzed and compared with sham-fed controls.

Results.

Graft assessment using NMP confirmed that preconditioning significantly improved ATP production, markers for hepatobiliary function (total bile production, biliary bilirubin, and bicarbonate), and significantly lowered levels of lactate, glucose, and apoptosis. After orthotopic liver transplantation, metformin preconditioning significantly reduced transaminase levels.

Conclusions.

Preconditioning with metformin lowers hepatobiliary injury and improves hepatobiliary function in an in situ and ex situ model of rat donor liver transplantation.

Comprehensive and innovative techniques for liver transplantation in rats: A surgical guide

AIM: To investigate our learning curves of orthotopic liver transplantation (OLT) in rats and the most important factor for successful surgery.

METHODS: We describe the surgical procedures for our rat OLT model, and determined the operator learning curves. The various factors that contributed to successful surgery were determined. The most important surgical factors were evaluated between successful and unsuccessful surgeries.

RESULTS: Learning curve data indicated that 50 cases were required for operator training to start a study. Operative time, blood loss, warm ischemic time, anhepatic phase, unstable systemic hemodynamic state, and body temperature after surgery significantly affected surgery success by univariate analysis, while the anhepatic phase was the most critical factor for success by multivariate analysis.

CONCLUSION: OLT in rats is the only liver transplantation model that provides clinically relevant and reliable results. Shortened anhepatic phase is key to success in this model.

Disseminated tumor cells homing into rats' liver: a new possible mechanism of HCC recurrence

AIM

To detect the origin of hepatocellular carcinoma (HCC) recurring and attempt to propose a new recurrent mechanism.

METHODS

Orthotopic liver allotransplantation was performed on male rats with HCC- induced by diethylnitrosamine using female donors. Metastatic tumors in transplanted livers were obtained. A DNA probe that exhibits specificity for the rat Y chromosome was generated by using a set of primers specific to murine sry gene. In situ hybridization (ISH) for Y chromosome was used to detected the origin of HCC recurring. Male HCC tissue was designed to be positive control. ISH on female tissue and using non-labeled with DIG probe was thought to be negative control.

RESULTS

Positive marks were seen through ISH for Y chromosome in recurrent tumor tissue and positive control. No signal was detected in both negative controls.

CONCLUSION

Recurrent HCC after liver transplantation originated from disseminated tumor cells in recipients. Extrahepatic cells homing into liver may be a new HCC recurrence mechanism. Likewise, it implicates that this mechanism is responsible for HCC recurring after hepatectomy.

The prevention of graft-versus-host disease by the serum of liver retransplanted rats

The effect of serum from orthotopic liver retransplanted rats (re-OLT serum) on graft-versus-host disease (GVHD) was studied in rats. In the re-transplantation model of rat liver, orthotopic liver transplantation (OLT) was carried out in the DA (RT1a) into PVG (RT1c) combination; two days later the DA liver was removed and a new PVG liver implanted into the same recipient (re-OLT). In the in vivo GVHD model, male PVG rats were sublethally irradiated and injected intravenously with 3 x 10(8) DA or BN (RT1n) spleen through the penial vein. Within 1 h of the inoculation, rats of the experimental group were injected with 1 ml of re-OLT serum taken at postoperative day (POD) 7. Rats in the control group received 1 ml of normal PVG serum or syngeneic re-OLT serum (PVG-PVG, PVG-PVG). All PVG rats in the control groups died of GVHD within 21 days after the inoculation of DA or BN spleen lymphocytes. However, when the animals were treated with re-OLT serum, 100% (6/6) of the rats survived more than 60 days, following inoculation with DA lymphocytes but not with BN lymphocytes. The POD 7 re-OLT serum showed a strong inhibition against DA anti-PVG mixed lymphocyte reaction (MLR), although re-OLT serum did not contain soluble DA class I antigens, anti-DA class I or II antibody. The potential GVHD inhibitory factors in re-OLT serum may be two unique immunosuppressive proteins, which have been detected by SDS PAGE and reported previously. We conclude that re-OLT serum has immunosuppressive factors, which, at least in part, prevented the induction of GVHD in rats.

Novel immunosuppressive proteins purified from the serum of liver-retransplanted rats

Liver grafts between certain rat strain combinations, such as DA (RT1a)-into-PVG (RT1c), are accepted without the use of immunosuppressive agents. To explore the nature and role of serum proteins in liver-induced immunosuppression, we have developed a retransplantation model of rat liver grafting. In this procedure, orthotopic liver transplantation (OLT) is carried out in the DA-into-PVG combination; two days later the DA liver is removed and a new PVG liver implanted into the same recipient (re-OLT). Serum from re-OLT rats was immunosuppressive when tested in mixed lymphocyte reactions (MLR). Three novel proteins were detected in re-OLT serum by SDS-PAGE, with sizes of 180 kD, 87 kD, and 10 kD. The N-terminal sequences of these were distinct and did not match protein sequences in the computer databases, although there was some homology between the 10 kD sequence and the beta-chain of rat hemoglobin. Purified 87 kD and 10 kD proteins were immunosuppressive in MLR; in both cases suppression was dose-dependent and nonstimulator-specific. Production of the 180 kD and 87 kD molecules required the presence of the recipient spleen. We conclude that re-OLT serum contains novel immunosuppressive proteins, which may be products of immune recognition and associated with the immediate termination of graft rejection.