Dynamical changing patterns of histological structure and ultrastructure of liver graft undergoing warm ischemia injury from non-heart-beating donor in rats

AIM： To investigate the histological and ultra-structural characteristics of liver graft during different of warm ischemia time （WIT） in rats and to predict the maximum limitation of liver graft to warm ischemia. METHODS： The rats were randomized into 7 groups undergoing warm ischemia injury for 0, 10, 15, 20, 30, 45 and 60 min, respectively. All specimens having undergone warm ischemia injury were investigated dynamically by light and electron microscopy, and histochemistry staining. After orthotopic liver transplantation （OLT）, the recovery of morphology of liver grafts after 6, 24 and 48 h was observed. RESULTS： The donor liver from non-heart-beating donors （NHBD） underwent ischemia injury both in the warm ischemia period and in the reperfusion period. Morphological changes were positively related to warm ischemia injury in a time-dependent manner during the reperfusion period. The results demonstrated that different degrees of histocyte degeneration were observed when WIT was within 30 min, and became more severe with the prolongation of WIT, no obvious hepatocyte necrosis was noted in any specimen. In the group undergoing warm ischemia injury for 45 min, small focal necrosis occurred in the central area of hepatic Iobule first. In the group undergoing warm ischemia injury for 60 rain, patchy or diffused necrosis was observed and the area was gradually extended, while hepatic sinusoid endothelial cells were obviously swollen. Hepatic sinusoid was obstructed and microcirculation was in disorder.CONCLUSION： The rat liver graft undergoing warm ischemia injury is in the reversible stage when the WIT is within 30 min. The 45 min WIT may be a critical point of rat liver graft to endure warm ischemia injury. When the WIT is over 60 min, the damage is irreversible.

Dynamical changing patterns of glycogen and enzyme histochemical activities in rat liver graft undergoing warm ischemia injury

AIM:To investigate the changing patterns of glycogen and enzyme histochemical activities in rat liver graft under a different warm ischemia time (WIT) and to predict the tolerant time limitation of the liver graft to warm ischemia injury. METHODS: The rats were randomized into five groups, WIT was 0,15,30,45,60 min, respectively, and histochemical staining of liver graft specimens was observed. The recovery changes of glycogen and enzyme histochemistry activities were measured respectively 6 and 24 h following liver graft implantation. RESULTS: The activities of succinic dehydrogenase, cytochrome oxidase, apyrase (Mg++-ATPase) and content of glycogen were decreased gradually after different WIT in a time-dependent manner. The changes were significant when WIT was over 30 min. CONCLUSION: Hepatic injury is reversible within 30 min of warm ischemia injury. Glycogen and enzyme histochemistry activities of liver grafts and their recovery potency after reperfusion may serve as criteria to evaluate the quality of liver grafts.

Influence of warm ischemia injury on hepatic functional status and survival of liver graft in rats

OBJECTIVES: To investigate the changing patterns of functional and histological status, observe the posttransplantation survival of liver graft under different warm ischemia time (WIT) in rats, and determine the maximum limitation of liver graft to warm ischemia. METHODS: According to WIT, the rats were randomized into 7 groups, with WIT of 0, 10, 15, 20, 30, 45, 60 minutes respectively. Serum concentrations of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase were measured at 1, 2, 3 and 5 days after orthotopic liver transplantation respectively. Liver graft specimens were observed histopathologically at the same interval. The rats' survival in each subgroup was observed. RESULTS: In terms of graft survival, there was no significant difference between subgroups within 30-minute WIT. In the group with 30-minute WIT, the recipient rats' survival rate was 83.3% (10/12) at one week, 58.3% (7/12) at one month, and 50.0% (6/12) at 3 months. In the group with 45-minute WIT, the recipient rats' survival rate was 66.7% (8/12) at one week, 33.3% (4/12) at one month, and 8.3% (1/12) at 3 months, whereas only 8.3% (1/12) of the rats had one-week survival in the group with 60-minute WIT. CONCLUSIONS: These results indicate that rat liver graft could be safely subject to warm ischemia within 30 minutes. When WIT is prolonged to 45 minutes, the recipients long-term survival is severely insulted, and both function and histological structure of liver graft may develop irreversible damage when WIT is prolonged to 60 minutes.

Energy metabolism and survival of liver grafts from non-heart-beating donor rats with warm ischemia injury

BACKGROUND: The shortage of donor livers is a critical limiting factor for the use of liver transplantation in treatment of end-stage liver diseases. Organs from non- heart-beating donors seem to be an effective option to alleviate this problem. Warm ischemia injury, however, directly influences the grafts' activity and functional recovery after operation. We investigated the energy metabolism and post-transplant survival of liver grafts after different warm ischemia times (WITs) in rats and determined the maximum limit for liver grafts with warm ischemia. METHODS: Rats were randomized into 7 groups with WITs of 0 (control), 10, 15, 20, 30, 45 or 60 minutes. The indices of energy metabolism were measured by reversed- phase high performance liquid chromatograpy and all liver graft specimens were subjected to ultrastructural observation. After orthotopic liver transplantation (OLT), the recovery of energy metabolism in liver grafts after 24 and 48 hours and the survival of the rats were assessed. RESULTS: The levels of adenosine triphosphate (ATP) and energy charge (EC) decreased gradually after different WITs in a time-dependent manner, and this was especially significant within 30 minutes. The levels of ATP and EC in liver grafts with 30 minutes of warm ischemia largely recovered 24 hours after OLT, with 45 minutes of warm ischemia partially recovered 48 hours after OLT, and with 60 minutes of warm ischemia, hardly recovered even 48 hours after OLT. The survival time after OLT did not significantly change with up to 30 minutes of WIT, while long-term survival was reduced with 45 and 60 minutes of WIT.CONCLUSIONS: The levels of ATP and EC after OLT may be important criteria for evaluating the quality of a liver graft. The WIT of a liver graft is closely related to the recovery of hepatic energy metabolism and the graft survival.

Dynamic microcirculatory changes in liver graft from non-heart-beating donor with warm ischemia injury in rat

BACKGROUND: Since the 1990s, liver grafts from non- heart-beating donor (NHBD) have become an alternative because of the deficiency of grafts from heart-beating-do- nors (HBDs). Warm ischemia injury, however, directly influences the grafts' activity and functional recovery after operation. We investigated the microcirculatory change of liver graft at different warm ischemia time (WIT) in rats and determined the maximum limitation of liver graft to warm ischemia. METHODS: According to WIT, 120 rats were divided ran- domly into 5 groups of 0, 15 , 30 , 45 , 60 minutes respec- tively. The microcirculatory changes of their liver grafts were measured including serum level of hyaluronic acid (HA) and ultrastructural changes. After orthotopic liver transplantation (OLT), the recovery of microcirculation of the liver grafts after 24 hours, 48 hours and 3 days was ob- served. RESULTS: Microcirculatory changes and function of the liver grafts became normal after reperfusion when the WIT was less than 30 minutes. In the 45-minute WI group, part of blood sinusoids was full of cytoplasmic blebs stemming from the microvilli of hepatocytes and hemocytes. The se- rum level of HA in each group after 45 minutes of WI re- covered after reperfusion. CONCLUSIONS: The microcirculatory change of rat liver graft is reversible when the WIT is less than 30 minutes: rat liver graft could be safely subject to warm ischemia within30 minutes. The maximal 45 minutes of WI can be tolera- ted by the microcirculatory function of liver graft. After 60 minutes of WI, irreversible disturbance of microcirculation may appear.