Background: In clinical liver transplantation, whether the delay of hepatic arterial ischaemia increases biliary fibrosis or not is controversial. We designed a liver transplantation model to test this controversy and explore its mechanism.
Methods: Twelve dogs were divided into two groups randomly: hepatic arterial ischaemia (HAI) and control groups. In HAI group, hepatic artery was perfused 60 minutes after portal perfusion, but in control group, hepatic arterial perfusion was simultaneous with portal perfusion. The pathological changes of intrahepatic bile ducts were observed. Transforming growth factor beta 1 (TGF-beta1), expressed in epithelial cells of intrahepatic bile duct, was detected by immunohistochemical streptoadividin-biotin complex method. Expressions of Smad3, P-Smad3 and the transcriptional levels of alpha smooth muscle actin (alpha-SMA) mRNA in intrahepatic bile ducts were detected by Western blotting and RT-PCR respectively.
Results: Compared with the control group, more collagen deposition and leucocytic infiltration could be seen in biliary vessel walls. Significantly more buffy particles, which are the proteins of TGF-beta1, could be seen in biliary epithelial cells. P-Smad3 and alpha-SMA mRNA (as ratio to corresponding beta-actin) in intrahepatic bile ducts were 1.82 +/- 0.18 and 1.86 +/- 0.73 respectively in HAI group, significantly higher than those in control group (0.59 +/- 0.09 and 0.46 +/- 0.18, respectively).
Conclusions: Hepatic arterial ischaemia could increase the deposition of collagen fibres, trigger the transdifferentiation of myofibroblasts in intrahepatic bile duct and might result in biliary fibrosis by activating the TGF-beta1 signalling pathway.