Using Tree Shrews (Tupaia belangeri) as a Novel Animal Model of Liver Transplantation

Liver transplantation (LT) is most effective and promising approach for end-stage liver disease. However, there remains room for further improvement and innovation, for example, to reduce ischemic reperfusion injury, transplant rejection and immune tolerance. A good animal model of LT is essential for such innovation in transplant research. Although rat LT model has been used since the last century, it has never been an ideal model because the results observed in rat may not be applied to human because these two species are genetically distinct from each other. In this study, we for the first time performed LT using the tree shrew (Tupaia belangeri), a species in the Order Scandentia which is closely related with primates, and evaluated the possibility to adopt this species as a new model of LT. We performed LT on 30 animals using the two-cuff technique, examining the success rate, the survival rate and the immunological reaction. The recipient operation time was 60 min averagely, and we limited the time of the anhepatic phase within 20 min. Twenty-seven (90%) of the animals survived for at least 3 days after the transplantation. Thirteen animals that did not receive any immunosuppressive drug died in 8 days mostly because of acute rejection effect (n=9), similar to the reaction in human but not in experimental rat. The rest 14 animals that were given rapamycin survived significantly longer (38 days) and half of them survived for 60 days until the end of the study. Our results suggest that performing LT in tree shrews can yield high success rate and high survival rate. More importantly, the tree shrews share similar immunological reaction with human. In addition, previous genomics study found that the tree shrews share more proteins with human. In sum, the tree shrews may outperform the experimental rats and could be used as a better and cost-effective animal model for LT.