Currently, there is a large discrepancy between the number of donated liver organs and the number of patients waiting for a donated liver. The shortage of liver organs is a global problem. To expand the donor pool, split liver transplantation (LTx) and living donor LTx were developed to use a partial liver as a graft1.
To further investigate the mechanism behind partial liver transplantation (PLTx), relevant animal models have been established2,3,4,5. In rat PLTx, the liver lobes are resected in vivo and ex vivo to mimic the conditions of the living donor LTx and split LTx, respectively, in human. A paper published in the Journal of Visualized Experiments presented a detailed protocol involving a 50% rat PLTx using an ex vivo hepatectomy5. However, a rat PLTx with an in vivo hepatectomy has not yet been reported in the visualized literature.
In addition to the difference between in vivo and ex vivo hepatectomies, the technique of performing a hepatectomy itself also plays an important role in determining the outcome of PLTx. Currently, in many surgical studies using the rat PTLx model, the liver lobes were resected after placing a simple ligation at the pedicle of the liver lobe2,3,6,7,8,9. However, placing a simple ligation before resection is not suitable for all liver lobes, as different liver lobes have different shapes and sizes. A simple ligation at the base of the median lobe carries a high risk of causing a constriction of the vena cava, which might eventually affect the outflow of the partial liver graft10,11. Therefore, an update hepatectomy technique based on knowledge of the rat hepatic anatomy is required in the field of rat PTLx.
In the protocol described in this study, an updated vessel-oriented 70% hepatectomy was incorporated into the procedure of the rat PLTx. The portal veins and hepatic arteries of the left lateral lobe (LLL) and median lobe (ML) were dissected and divided individually before removal of the liver parenchyma. Then, the hepatic veins of the LLL and ML were ligated by piercing sutures. By using individual ligations and multiple piercing sutures rather than placing a simple ligation, the remnant stump of the ML was able to spread over the vena cava. Hence, the constriction of the infrahepatic vena cava caused by a surgical ligation was avoided. Additionally, occlusion of the blood supply of the LLL and ML by individual ligations before removal of the liver parenchyma decreased the rate of bleeding in the remnant liver stump, thereby minimizing the influence of blood loss on the experiments11.
For microsurgeons, it is a significant challenge to reconstruct the proper hepatic artery (PHA) of a liver graft because of the extremely small diameter of this vessel. Although the question of whether re-arterialization in LTx is truly necessary is still under debate12,13,14, numerous microsurgical techniques for reconstructing the hepatic artery have been proposed14. Here, we introduce a novel technique for re-arterialization of the liver graft, which anastomoses the common hepatic artery (CHA) to the enlarged PHA in an end-to-side manner. By using this end-to-side technique, two hepatic arteries are connected with an anastomosis of a larger diameter. The larger the diameter of the anastomosis is, the easier hand suturing is to perform and the greater the improvement in the patency of the anastomosis becomes.