Effects of bone marrow mesenchymal stem cells combined with normothermic mechanical perfusion on biliary epithelial cells donated after cardiac death in rats / 中华危重病急救医学

ABSTRACT

Objective@#To investigate the protective effect of bone marrow mesenchymal stem cells (BMMSC) combined with normothermic mechanical perfusion (NMP) on biliary epithelial cells (BEC) in rats receiving donation after cardiac death (DCD) donor liver transplantation.@*Methods@#The BMMSC were isolated from male Sprague-Dawley (SD) rats aged 2-3 weeks and weighing 40-60 g, and then cultured, identified and expanded to the third generation in vitro. Male SD rats aged 6-8 weeks and weighing 200-220 g were divided into sham-operated group (Sham group), static cold storage (SCS group), simple NMP group (NMP group) and BMMSC combined with NMP group (BMMSC+NMP group) by random number table method with 44 rats in each group. The DCD donor liver transplantation models in rats were reproduced with 30-minute warm ischemic time. While the rats in Sham group merely received perihepatic ligaments-separation, which did not affect their liver blood supply, and then their incisions were sutured after 30 minutes. The DCD donor grafts in SCS group were preserved in the University of Wisconsin (UW) cold storage solution for 4 hours. While the DCD donor grafts in the NMP group and the BMMSC+NMP group were perfused with the DMEM/F12-based culture solution or combined with BMMSC for 4 hours through the established ex vivo NMP system. The orthotopic liver transplantation model was reproduced, and the survival rate of the recipients was observed at 0, 1, 7 and 14 days after liver transplantation. The biochemical liver function of rats in different groups was determined at each time point after operation. The morphological changes in bile ducts of liver grafts were observed by hematoxylin-eosin (HE) staining, and the expression of cytokeratin 19 (CK19) was determined qualitatively by immunohistochemistry and quantitatively by Western Blot after protein extraction from BEC in liver samples.@*Results@#The morphology, differentiation function and phenotypic identification of BMMSC confirmed that the stem cells used in this experiment were standard BMMSC. The survival rates of rats in the NMP group and the BMMSC+NMP group were significantly higher than that in the SCS group at 0, 1, 7 and 14 days after operation. The increase was more significant in the BMMSC+NMP group, with 100% on postoperative day (POD) 0, and the 14-day survival rate was still significantly higher than that in the SCS group and the NMP group [80.0% (16/20) vs. 20.0% (4/20), 70.0% (14/20), both P < 0.05]. As the time after liver transplantation prolonged, the liver function parameters of rats in the SCS group were deteriorated gradually, which reached the peak at 1-7 days after operation. The damage of biliary tissue increased gradually under the microscope, and the injury was most serious on POD 7 in the SCS group, showing a lot of balloon-like changes in hepatocytes, with obvious bile duct dilatation accompanied by large area inflammatory cell infiltration. Immunohistochemistry and Western Blot showed that the expression of CK19 in BEC cytoplasm was decreased gradually in the SCS group, reached the lowest on POD 7, and then gradually increased. The BMMSC+NMP group and the NMP group were significantly better than the SCS group in terms of liver function, pathological injury of biliary tract and CK19 expression in BEC, and the improvement was more significant in the BMMSC+NMP group. These results suggested that the protective effects of BMMSC combined with NMP on BEC was significantly better than that of the SCS and NMP.@*Conclusion@#Preservation of rat DCD donor liver by BMMSC combined with NMP can reduce the BEC injury after liver transplantation significantly, thus improving both the prognosis and the survival rate after transplantation.