The benefits of ligating the lobar portal triads before partial hepatectomy in the mouse

Extended liver resection in mice: state of the art and pitfalls-a systematic review

Background

Rodent models of liver resection have been used to investigate and evaluate the liver’s complex physiology and pathology since 1931. First documented by Higgins and Anderson, such models were created to understand liver regeneration mechanisms to improve outcomes in patients undergoing extensive liver resection for liver cancer or other underlying liver diseases.

Methods

A systematic search was conducted using Pubmed, gathering publications up to January 2019, which engaged with the mouse model of extended liver resection as a method itself. The results of this search were filtered according to their language, novelty, and relevancy.

Results

The Boolean search found 3741 articles on Pubmed, with 3130 publications remaining when filtered by language and the presence of a full text. In total, 21 of these publications examined the key themes of the animal model described. The mortality varied from 0 to 50% depending on the surgeon's experience and the resection method. The liver resection was mainly performed with classic sutures (14 out of 21 publications) and isoflurane was used for anaesthesia (10 out of 21 publications) in combination with analgesics (buprenorphine or ketamine/xylazine). The most used mouse strain was C57BL/6 (7 of 21 publications) which was on average 11 weeks old with a weight of 23 g.

Conclusion

Through the overview, laid out in the selected publications, this paper reviews the shift of the extended liver resection model from rat to the mouse, describes the state of the art in the experimental setting, and discusses the possible limitations and pitfalls. Clearly, the extended liver resection in mice is a reproducible, practical and easy to learn method.

A Novel Mouse Model of Liver Ischemic/Reperfusion Injury and its Differences to the Existing Model

BACKGROUND

Ischemia of the cephalad lobes (70% of liver mass) is a frequently employed mouse hepatic ischemia/reperfusion (I/R) model that does not involve outflow occlusion. This model produces results with relatively large variances.

MATERIALS AND METHODS

A novel model of ischemia of the left lateral lobe (35% of liver mass) that involves temporarily occluding the blood supply to the cephalad lobes to expel blood followed by occlusion of both the inflow and outflow of the left lateral lobe, was developed. Mice in the 35% (novel) and 70% (existing) model groups were subjected to I/R injury, and biochemical and histological analyses of blood and liver samples were performed. Tissue oxygen partial pressure (tPO2) measurements in the ischemic lobes were also performed to determine whether the hepatic tissue was in a stable hypoxic state. Statistical analyses of the biochemical results, histological scores, and tPO2 levels were performed from which coefficients of variation (CV) were calculated.

RESULTS

The CVs of the aminotransferase activities, histological scores, and tPO2 levels were much lower in the 35% group than those in the 70% group. The tPO2 measurements demonstrated that inflow occlusion in the 70% model did not result in a stable hypoxic state, even after the portal triads were ligated and severed, indicating that there was blood reflux from the vena cava, which would be responsible for the variations in results with the 70% I/R model.

CONCLUSIONS

The new 35% I/R model leads to reproducible results because both inflow and outflow of the ischemic lobe are occluded.

Simple and reproducible hepatectomy in the mouse using the clip technique

AIM: To investigate the reliability of massive hepatectomy models by using clip techniques.

METHODS: We analyzed anatomical findings in 100 mice following massive hepatectomy induced by liver reduction > 70%. The impact of various factors in the different models was also analyzed, including learning curves, operative time, survival curves, and histopathological findings.

RESULTS: According to anatomical results, models with 75%, 80%, and 90% hepatectomy produced massive hepatectomy. Learning curves and operative times were most optimal with the clip technique. Each hepatectomy performed using the clip technique produced a reasonable survival curve, and there were no differences in histopathological findings between the suture and clip techniques.

CONCLUSION: Massive hepatectomy by the clip technique is simple and can provide reliable and relevant data.

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.