Establishment of an animal model of ischemic type intrahepatic biliary lesion in rabbits

Contrast-Enhanced Ultrasound for Biliary Ischemia: A Possible New Clinical Indication

OBJECTIVES

Biliary perfusion is considered to contribute to biliary diseases, but routine imaging methods are insufficient to show it. This research investigated the ability of contrast-enhanced ultrasound (CEUS) for biliary perfusion in a biliary ischemia model.

METHODS

This research consisted of 2 parts. First, to determine whether CEUS enhancement of the tiny biliary wall represents biliary perfusion, a vascular tracer was used as a reference to evaluate the consistency with the enhancement of the biliary wall on CEUS and the staining by the vascular tracer under the conditions of occluded and recovered biliary perfusion. In the second part, the ability of CEUS for biliary ischemia was further evaluated with microvascular density measurement as a reference. The enhancement patterns were assigned CEUS scores, in which higher scores meant more decreased enhancement, and the diagnostic ability of CEUS was assessed by a receiver operating characteristic curve analysis.

RESULTS

The biliary wall was unstained by the vascular tracer and nonenhanced on CEUS when biliary perfusion was interrupted and was stained blue and enhanced after recovery. The biliary wall in the ischemia surgery group showed lower microvascular density measurements (P < .001), decreased enhancement levels (P < .001), and higher CEUS scores (P < .001). When a CEUS score of 3 or higher (obvious decrease of the biliary wall to hypoenhancement or nonenhancement in the arterial phase or rapid wash-out to nonenhancement in the portal venous phase) was applied, CEUS had sensitivity of 87.8%, specificity of 98.3%, accuracy of 93.8%, and an area under the receiver operating characteristic curve of 0.98.

CONCLUSIONS

Contrast enhancement of the biliary wall on CEUS represents biliary perfusion and has reasonably good diagnostic performance for biliary ischemia in an experimental animal setting.

Delayed rearterialization unlikely leads to nonanastomotic stricture but causes temporary injury on bile duct after liver transplantation

Nonanastomotic strictures (NAS) are common biliary complications after liver transplantation (LT). Delayed rearterialization induces biliary injury in several hours. However, whether this injury can be prolonged remains unknown. The correlation of this injury with NAS occurrence remains obscure. Different delayed rearterialization times were compared using a porcine LT model. Morphological and functional changes in bile canaliculus were evaluated by transmission electron microscopy and real-time PCR. Immunohistochemistry and TUNEL were performed to validate intrahepatic bile duct injury. Three months after LT was performed, biliary duct stricture was determined by cholangiography; the tissue of common bile duct was detected by real-time PCR. Bile canaliculi were impaired in early postoperative stage and then exacerbated as delayed rearterialization time was prolonged. Nevertheless, damaged bile canaliculi could fully recover in subsequent months. TNF-α and TGF-β expressions and apoptosis cell ratio increased in the intrahepatic bile duct only during early postoperative period in a time-dependent manner. No abnormality was observed by cholangiography and common bile duct examination after 3 months. Delayed rearterialization caused temporary injury to bile canaliculi and intrahepatic bile duct in a time-dependent manner. Injury could be fully treated in succeeding months. Solo delayed rearterialization cannot induce NAS after LT.

Effects of autologous bone marrow mononuclear cells implantation on cholangiocytes apoptosis in model of intrahepatic ischemic type biliary lesion in rabbits

AIM

To investigate the effects of autologous bone marrow mononuclear cells (BM-MNCs) implantation on regulation of cholangiocyte apoptosis in a model of intrahepatic ischemic type biliary lesion (ITBL) in rabbits.

MATERIALS AND METHODS

Thirty Japanese white rabbits were divided randomly into 3 groups (10 per group) including controls (group A), ITBL model (group B), and BM-MNCs implantation groups (group C). All rabbits underwent the same surgical procedure to prepare the liver for graft removal during transplantation. Subsequently, no additional vascular intervention was performed in group A. In group B, the hepatic artery and common bile duct were clamped with microvascular clips for 2 hours, where after the clips were removed to recover the blood supply. Group C received, BM-MNCs (10(8) cells per rabbit) injected through the hepatic artery after removing the clips. The animals were killed 4 weeks after operation. The survival rate, histopathologic examination, cholangiocyte apoptosis with terminal uridine nick-end labeling (TUNEL) staining and expressions of Bcl-2 and Bax proteins were examined using immunohistochemical staining.

RESULTS

Group A animals showed a survival of 100%; the rates in groups B and C were both 90%. Histopathologic examination revealed normal intrahepatic cholangiocytes in group A, obviously damaged ones in group B, and alleviated damage in group C. TUNEL staining indicated apoptosis of cholangiocytes in group B was more serious than that in group A or group C. Immunohistochemical staining demonstrated significantly decreased Bcl-2 expression in group B compared with that in group A; Bcl-2 expression in group C returned to the level of group A. Simultaneously, the Bax expression presented adverse results; the ratios of Bcl-2/Bax were ranked as group A > group C > group B.

CONCLUSION

Implantation of autologous BM-MNCs significantly reduced apoptosis of intrahepatic cholangiocytes and prevented or abated intrahepatic ITBL.

Establishment of a rat model of extrahepatic biliary ischemic stenosis

AIM: To develop a rat model of extrahepatic biliary ischemic stenosis.

METHODS: Forty-eight Sprague-Dawley rats were divided randomly and equally into four groups: rats undergoing sham operation and those subjected to clamping of the common bile duct with a clip for 60, 120, or 180 min. After scheduled clamping, the clip was removed to recover blood supply. The animals were killed 4 and 8 wk after operation. The survival, liver function, and histopathological changes were observed in rats of each group.

RESULTS: The survival rate was 100% in rats undergoing sham operation and those undergoing clamping for 60 or 120min, and 75% in those undergoing clamping for 180 min. At week 4, the body weight of rats undergoing clamping for 60, 120 or 180 min was lower than that of rats undergoing sham operation (240.4 g ± 11.5 g, 212.7 g ± 13.6 g, 200.6 g ± 11.8 g vs 260.6 g ± 15.7 g, all P < 0.05). Liver function parameters were higher in rats undergoing clamping for 60, 120 or 180 min than in those undergoing sham operation (ALT: 55.3 IU/L ± 5.3 IU/L, 215.6 IU/L ± 26.8 IU/L, 245.5 IU/L ± 38.5 IU/L vs 45.5 IU/L ± 3.9 IU/L, all P < 0.05; AST: 161.3 IU/L ± 15.9 IU/L, 645.3 IU/L ± 50.5 IU/L, 698.8 IU/L ± 46.7 IU/L vs 140.3 IU/L ± 6.1 IU/L, all P < 0.05; TILB: 8.5 μmol/L ± 1.2 μmol/L, 72.6 μmol/L ± 11.0 μmol/L, 78.7 μmol/L ± 12.2 μmol/L vs 6.1 μmol/L ± 1.2 μmol/L, all P < 0.05; ALP: 202.4 IU/L ± 20.7 IU/L, 815.4 IU/L ± 68.1 IU/L, 902.9 IU/L ± 96.6 IU/L vs 158.5 IU/L ± 23.6 IU/L, all P < 0.05; GGT: 10.6 IU/L ± 2.7 IU/L, 52.3 IU/L ± 8.6 IU/L, 57.4 IU/L ± 11.3 IU/L vs 7.6 IU/L ± 1.4 IU/L, all P < 0.05). Histopathological examination showed that biliary stenosis was not apparent and wall fibrosis was milder in rats undergoing sham operation and those undergoing clamping for 60 min, while severe biliary stenosis and wall fibrosis were observed in those undergoing clamping for 120 or 180 min. At week 8, these lesions could not regress spontaneously.

CONCLUSION: An animal model of extrahepatic biliary ischemic stenosis is successfully established with the clamping method in rats, which provides a useful tool for basic and clinical research of the etiology, development and prophylaxis of extrahepatic biliary ischemic stenosis after liver transplantation.