Surgical techniques of arterialized orthotopic liver transplantation in rats:

Prediction of rat liver transplantation outcomes using energy metabolites measured by microdialysis

BACKGROUND

Warm ischemia jeopardizes graft quality and recipient survival in donation after cardiac death (DCD) transplantation. Currently, there is no system to objectively evaluate the liver quality from DCD. The present study tried to use energy metabolites to evaluate the donor liver quality.

METHODS

We divided 195 Sprague-Dawley rats into five groups: the control (n = 39), warm ischemic time (WIT) 15 min (n = 39), WIT 30 min (n = 39), WIT 45 min (n = 39), and WIT 60 min (n = 39) groups. Three rats from each group were randomly selected for pretransplant histologic evaluation of warm ischemia-related damage. The remaining 36 rats were randomly divided into donors and recipients of 18 liver transplantations, and were subjected to postoperative liver function and survival analyses. Between cardiac arrest and cold storage, liver energy metabolites including glucose, lactate, pyruvate, and glycerol were measured by microdialysis. The lactate to pyruvate ratio (LPR) was calculated.

RESULTS

The changes in preoperative pathology with warm ischemia were inconspicuous, but the trends in postoperative pathology and aminotransferase levels were consistent with preoperative energy metabolite measurements. The 30-day survival rates of the control and WIT 15, 30, 45, and 60 min groups were 100%, 81.82%, 76.92%, 58.33%, and 25.00%, respectively. The areas under the receiver operating characteristic curves of glucose, lactate, glycerol, and LPR were 0.87, 0.88, 0.88, and 0.92, respectively.

CONCLUSION

Glucose, lactate, glycerol, and LPR are predictors of graft quality and survival outcomes in DCD transplantation.

Comparison of Methods for the Reconstruction of the Hepatic Artery in Mouse Orthotopic Liver Transplantation

Background

The mouse model of arterialized orthotopic liver transplantation (AOLT) has played an important role in biomedical research. The available methods of sutured anastomosis for reconstruction of the hepatic artery are complicated, resulting in a high incidence of complications and failure. Therefore, we developed and evaluated a new model of AOLT in mice.

Materials and methods

Male inbred C57BL/6 mice were used in this study. A continuous suture approach was applied to connect the suprahepatic inferior vena cava (SHVC). The portal vein and infrahepatic inferior vena cava (IHVC) were connected according to the "two-cuff" method. The common bile duct was connected by a biliary stent. We used the stent (G3 group) or aortic trunk (G2 group) to reconstruct the hepatic artery. The patency of the hepatic artery was verified by transecting the artery near the graft after one week. The survival rate of the recipients and serum alanine aminotransferase (ALT) levels, hepatic pathologic alterations, apoptosis and necrosis were observed at one week postoperatively.

Results

The patency of the hepatic artery was verified in eight of ten mice in G3 and in six of ten mice in G2. The 7-day survival rate, extents of necrosis and apoptosis, and TGF-β levels were not significantly different among the three groups (P>0.05). However, the serum ALT levels and operation time were markedly lower in G3 compared with G2 or G1 (both P<0.05).

Conclusions

Reconstruction of the hepatic artery using a stent can be performed quickly with a high rate of patency. This model simplifies hepatic artery anastomosis and should be promoted in the field of biomedical research.

Impact of hepatic arterial reconstruction on orthotopic liver transplantation in the rat

Orthotopic liver transplantation (OLT) models in rats have been investigated in many studies, but detailed information on the impact of hepatic artery (HA) reconstruction on postoperative factors remains to be investigated. HA reconstruction also requires advanced skills. The effect of the reconstruction of the HA by a hand-suture technique in rats with a whole-liver syngeneic graft was investigated. Long-term survival, histopathological assessment, immunohistological evaluation, and blood biochemistry were investigated until postoperative day (POD) 28. From the early postoperative period, significant differences between OLTs with or without HA reconstruction were found in graft parenchymal damage, induction of apoptosis, and transaminase levels, though survival curves and the coagulation profile showed no differences. In OLT without HA reconstruction, biliary proliferation was decreased at POD 5-14, and total bilirubin level was increased at PODs 10 and 14. The study indicates that HA reconstruction is required for reliable OLT in rats.

The current state of knowledge of hepatic ischemia-reperfusion injury based on its study in experimental models

The present review focuses on the numerous experimental models used to study the complexity of hepatic ischemia/reperfusion (I/R) injury. Although experimental models of hepatic I/R injury represent a compromise between the clinical reality and experimental simplification, the clinical transfer of experimental results is problematic because of anatomical and physiological differences and the inevitable simplification of experimental work. In this review, the strengths and limitations of the various models of hepatic I/R are discussed. Several strategies to protect the liver from I/R injury have been developed in animal models and, some of these, might find their way into clinical practice. We also attempt to highlight the fact that the mechanisms responsible for hepatic I/R injury depend on the experimental model used, and therefore the therapeutic strategies also differ according to the model used. Thus, the choice of model must therefore be adapted to the clinical question being answered.

Hepatic arterial reconstruction for orthotopic liver transplantation in the rat

BACKGROUND

Orthotopic liver transplantation (OLT) models in rats have been investigated in many studies. The reconstruction of hepatic artery is required for reliable OLT and also requires advanced skills.

METHODS

The hepatic artery reconstructions by a hand-suture technique and a new method using a micro T-tube were investigated in rats with a whole-liver syngeneic graft. Operative time and postoperative patency were compared between the hand-suture and micro T-tube techniques.

RESULTS

Our technique using the micro T-tube shortened the operative time of recipient surgery compared with the hand-suture technique and prolonged the operative time for the donor. The patency ratio was maintained at 24h after OLT with hand suturing but was significantly reduced with the micro T-tube, which had a patency ratio of 0.83 only up to 6h after OLT.

CONCLUSION

The micro T-tube technique may have potential usefulness in the rat OLT model but requires further modification.

A novel end-to-side anastomosis technique for hepatic rearterialization in rat orthotopic liver transplantation to accommodate size mismatches between vessels

BACKGROUND/AIMS

We present our modification of a sutured arterial anastomosis in orthotopic rat liver transplantation as well as a literature survey and analysis of the existing techniques of rearterialization with regard to technical difficulties and potential limitations.

METHODS

The donor common hepatic artery (CHA) was anastomosed to the enlarged lumen of the recipient proper hepatic artery (PHA), tailored to match the size of the donor CHA, with an end-to-side interrupted suture technique. Vascular patency of hepatic rearterialization was assessed both intraoperatively and at the time the liver grafts were harvested (postoperative days 2 and 28). The effect of arterialization on hepatic morphology was confirmed by histological examination and compared to nonarterialized rat orthotopic liver transplantation.

RESULTS

The CHAs had a significantly larger diameter (up to 3-fold) compared to the PHAs, which represents a considerable size mismatch. The anastomosis procedure including the size adaptation required 15-25 min. All anastomoses were patent immediately, 5 min after rearterialization and at both harvest time points. The liver lobular architecture was intact in the rearterialized group, whereas a moderate degree of bile duct proliferation and portal/lobular lymphocytic infiltration were observed in the nonarterialized group.

CONCLUSION

The new technique is a time-consuming and microsurgically challenging but universally applicable and robust procedure accommodating even a substantial mismatch in vessel diameter.

The value of microsurgery in liver research

The use of an operating microscope in rat liver surgery makes it possible to obtain new experimental models and improve the already existing macrosurgical models. Thus, microsurgery could be a very valuable technique to improve experimental models of hepatic insufficiency. In the current review, we present the microsurgical techniques most frequently used in the rat, such as the portacaval shunt, the extrahepatic biliary tract resection, partial and total hepatectomies and heterotopic and orthotopic liver transplantation. Hence, reducing surgical complications allows for perfecting the resulting experimental models. Thus, liver atrophy related to portacaval shunt, prehepatic portal hypertension secondary to partial portal vein ligation, cholestasis by resection of the extrahepatic biliary tract, hepatic regeneration after partial hepatectomies, acute liver failure associated with subtotal or total hepatectomy and finally complications derived from preservation or rejection in orthotopic and heterotopic liver transplantation can be studied in more standardized experimental models. The results obtained are therefore more reliable and facilitates the flow of knowledge from the bench to the bedside. Some of these microsurgical techniques, because of their simplicity, can be performed by researchers without any prior surgical training. Other more complex microsurgical techniques require in-depth surgical training. These techniques are ideal for achieving a complete surgical training and more select microsurgical models for hepatology research.

Simultaneous orthotopic liver-kidney transplantation with hepatic arterial reconstitution in rats

Although combined liver-kidney (LK) transplantation has been effectively used in patients with end-stage liver disease and concurrent renal failure, a small animal model has been rarely described because of the technical difficulties. Herein, we have described techniques of a modified simultaneous LK transplantation model in rats. We have modified the techniques to perform 47 combined LK transplants in rats with reconstructed hepatic artery and renal vessels by a microvascular sleeve method and an end-to-end anastomosis technique without cross-clamping the vena cava and abdominal aorta, respectively. An average donor operation time was 34.4+/-6.3 min with cold ischemia times of 49.7+/-6.5 min and 61.3+/-4.1 min for liver and kidney grafts, respectively. The total time for recipient operation was 96.8+/-9.4 min with a 4-wk survival rate of 92.3% (36/39). A cumulative hepatic and renal arterial patency rate reached 90.2% (37/41). Normal grafts function tests were observed within the first week post-transplant, as well as normal histopathology studies of the 2 grafts in wk 4 post-transplant. Our method proves to be practical and may contribute to a wider use of the model in the studies of allograft rejection and tolerance induction during combined LK transplantation.

Improvement of microsurgical techniques in orthotopic rat liver transplantation

BACKGROUND

Because of the limited tolerance to portal venous clamping, the model of liver transplantation in rats represents a difficult task, which requires a great proportion of experience. Since techniques that include the introduction of an artificial stent increase the risk of thrombosis, it was our goal to modify the classical vascular hand-sewn venous anastomosis technique by using a modified end-to-end knotless procedure.

MATERIALS AND METHODS

Seventy-two animals were randomly assigned to 1 of 2 experimental groups, which differed by the technique for the 3 venous anastomoses (supra- and infrahepatic vena cava, portal vein). Group 1 comprised the established suturing technique for rat liver transplantation, whereas all venous anastomosis of the second group were performed using our modified technique.

RESULTS

With our method, average anhepatic time could be significantly reduced from 14 min 10 s (+/-100 s) to 11 min 40 s (+/-60 s) (P < 0.001). Kaplan-Meier survival rates demonstrated a better 7-d survival for the knotless (94%) compared to the classic technique (83%) (not significant, P = 0.137). Biliary complications were low in both groups but tended to be higher in the classical group.

CONCLUSIONS

Our modified knotless anastomosis proves to be equally safe in regard to complications, improves timing, and provides excellent results in the model of orthotopic rat liver transplantation.