Microvessel density at different levels of normal or injured bile duct in dogs and its surgical implications.

BACKGROUND: Ischemic recurrent stricture after surgical repair for iatrogenic bile duct injury (BDI) remains a challenge in clinical practice. The present study was designed to investigate whether ischemia is universal and of varied severity at different levels of the proximal bile duct after BDI. METHODS: A total of 30 beagle dogs were randomly divided into control, BDI, and BDI-repaired groups. The BDI animal model was established based on the classic pattern of laparoscopic cholecystectomy-related BDI. The animals were sacrificed on postoperative day 15, and bile duct tissue was harvested to assess microvessel density (MVD) at selected levels of the normal, post-BDI and BDI-repaired bile duct with the CD34 immunohistochemistry technique. RESULTS: In the control group, MVD at level H (high level) was remarkably higher than that at level L (low level). No significant difference was found between MVDs at levels H and M (middle level), as well as at levels M and L. However, the tendency was noted that the closer the level to the hilus, the greater the MVD at that level. In both the BDI and BDI-repaired groups, MVDs at level H were generally greater than those at level L, despite the unremarkable differences between MVDs at neighboring levels. In these two groups, a similar tendency of MVD distribution to that in the control group was found; the closer the level to the injury site, the lower was the MVD at that level. Moreover, compared with the MDVs at the levels M and L in the control group, MVDs at the corresponding levels in the BDI and BDI-repaired groups were all remarkably reduced (P<0.05). In addition, MVDs at all three levels in the BDI group significantly declined further after BDI repair. CONCLUSIONS: After BDI, universal ischemic damage in the injured proximal bile duct develops close to the injury site, while close to the hilus, ischemia is relatively slight. High hepaticojejunostomy, rather than low biloenterostomy or end-to-end duct anastomosis, should be recommended for BDI repair. Great care should be taken to protect the peribiliary plexus during repair.

Prolonging warm ischemia reduces the cold preservation limits of liver grafts in swine.

BACKGROUND: The critical shortage of transplantable organs necessitates utilization of unconventional donors. But the safe time limits of cold preservation of liver grafts subjected to warm ischemia (WI) for up to 30 minutes from non-heart-beating-donors (NHBDs) has not been delineated. In this study, we investigated how the limits of cold ischemia (CI) in University of Wisconsin (UW) solution are changed in liver grafts subjected to WI from 10 to 30 minutes. METHODS: A simple porcine NHBD liver transplantation (LT) model was developed. In donors, livers were subjected to 10, 20 or 30 minutes of WI and subsequent different times of CI in UW solution. Animals were divided into three groups (WI 10 min, WI 20 min, WI 30 min, n=13 in each group) and nine subgroups (from CI 6 h to CI 28 h). One-week survival rates of recipients, hepatic function, liver energy metabolism, grafted liver microcirculation and pathological observations of the liver were compared. RESULTS: In the WI 10 min group, the one-week survival rate of the CI 20 h subgroup was significantly higher than in the other two subgroups (CI 24 h and CI 28 h) (P<0.05). Furthermore, the CI 20 h subgroup had a lower level of alanine aminotransferase (ALT), less pathological damage, a higher concentration of adenosine triphosphate (ATP) and microcirculatory blood flow in the grafted livers at 1 hour after reperfusion than the other two subgroups. The same trends were also found in the other two groups (WI 20 min and WI 30 min) and their subgroups. CONCLUSIONS: The cold preservation limits of the liver grafts shortened from 20 to 12 to 6 hours when WI time was prolonged from 10 to 20 to 30 minutes. Only the liver grafts within these time limits could be safely transplanted.

[Experimental study on tolerance time limits from warm ischemia to cold preservation of liver grafts].

OBJECTIVE: To investigate the tolerance time limits from warm ischemia to cold preservation of liver grafts. METHODS: Orthotopic liver transplantations (OLTs) were performed on Bama miniature swine. Morphological and functional changes of the liver grafts and biliary tracts after 10 minutes of warm ischemia followed by different durations of cold preservation and its reversibility were investigated. RESULTS: When the grafts were subjected to 10 minutes of warm ischemia followed by less than 16 hours of cold preservation, all animals could survive 1 week and there was no animal death from biliary necrosis. However, when the cold preservation time exceeded 16 hours, the incidence of biliary necrosis was significantly increased (P<0.05), and recipient death from bile leaks occurred. With further prolongation of the cold preservation time, primary graft nonfunction and intraoperative or early postoperative deaths occurred and the living animals all developed biliary necrosis. When compared with the less than 16 hours cold preservation group, the morphological scores and apoptosis index of the epithelial cells of bile ducts in grafts after reperfusion were significantly elevated in the more than 16 hours cold preservation group (P<0.05) and the activity of Na+-K+-ATPase and Ca2+-ATPase of bile ducts in grafts were also significantly reduced (P<0.05). Liver function tests showed that the recoveries of AST, AST, GGT and ALP were quicker in the 16 hours cold preservation group then those over 16 hour preservation ones. Correlation analysis revealed that the incidence of biliary necrosis was significantly correlated with the morphological score (r = 0.972) and with the apoptosis index of the epithelial cells of bile ducts in grafts after reperfusion (r = 0.931) and also correlated negatively (P<0.01) with the activity of Na+-K+-ATPase (r = -0.973) and Ca2+-ATPase (r = -0.973). CONCLUSIONS: It is concluded that with 10 minutes of warm ischemia, cold preservation of the grafts should not be longer than 16 hours in order to avoid early biliary necrosis, and the corresponding tolerance time limit of the livers to the cold preservation was less than 20 hours.

Cold preservation of pig liver grafts with warm ischemia and pentoxifylline-UW solution.

BACKGROUND: We undertook this study to investigate the safe time limits of cold preservation in UW solution of liver grafts subjected to warm ischemia (WI) for 20 min and the changes of the limits when pentoxifylline is added to UW solution. METHODS: The safe time limit was studied in a simple porcine orthotopic liver transplantation (LTx) model. In donors, livers were subjected to 20 min of WI and subsequent 12-h (group 1, n = 5), 16-h (group 2, n = 5), and 20-h (group 3, n = 3) cold preservation in UW solution, respectively. After the safe time limits were clear, another group (group 4, n = 5) was built to test whether or not the limits can be changed when pentoxifylline is added to UW solution in an unsafe time limit group. RESULTS: All five animals in group 1 survived up to 7 days of the survey endpoint. In group 2, only one animal survived up to the same survey endpoint and all animals in group 3 died within 12 h. The 1-week survival rate of group 1 was significantly higher than the other two groups. Group 1 had a lower level of alanine aminotransferase (ALT) or aspartase aminotransferase (AST) after LTx, less pathological damage, higher concentration of adenosine triphosphate (ATP) and higher microcirculation blood flux in the grafted liver tissue at 1 h after reperfusion than the other two groups. The results primarily showed that 12-h cold preservation was safe, 16 h was unsafe, and 20 h was highly unsafe. But when pentoxifylline was added to UW solution in cold preservation (16-h group, group 4), in contrast to group 2, the incidence of liver tissue necrosis and primary graft nonfunction was significantly lower in group 4 than in group 2. The 1-week survival rate of the pigs was 100% in the former and 20% in latter group. Levels of ALT and AST in recipients' artery blood, malondialdehyde and TNF-alpha concentration in grafted liver tissue, resistance of portal vein and hepatic artery after preservation in group 4 were significantly reduced, whereas microcirculation blood flux of the grafted liver, superoxide dismutase concentration and ATP concentration in grafted liver tissue were significantly elevated. CONCLUSIONS: The safe time limit of cold preservation in UW solution of liver grafts subjected to WI for 20 min was about 12 h and the limits can be prolonged to 16 h when pentoxifylline is added to UW solution. Many mechanisms were involved.