Preservation-reperfusion Injury Research Articles

Effects of pentoxifylline pretreatment on Kupffer cells in rat liver transplantation

Previous research with pentoxifylline (PTX), a methylxanthine phosphodiesterase inhibitor, suggests that this drug may be capable of suppressing the activation of Kupffer cells and thereby help decrease liver injury after transplantation. To investigate this possibility, the current study sought to determine whether the release of O2- and tumor necrosis factor (TNF) from Kupffer cells in donor livers can be suppressed if the organs are exposed to PTX before preservation. In an in vitro experiment, rat livers were flushed with PTX (25 mg/kg body weight) in University of Washington (UW) solution or UW solution alone (control) and then and stored in UW solution for either 4 or 24 hours. Kupffer cells then were purified and their degree of activation determined by measuring O2- release and the production of TNF after lipopolysaccharide stimulation. In an in vivo experiment, a group of rats underwent orthotopic liver transplantation with grafts prepared in the same manner as in the in vitro study. TNF and aspartate transaminase (AST) were measured in blood samples taken 3 hours and 24 hours after transplantation. Compared with controls, the Kupffer cells from grafts pretreated with PTX produced significantly less O2- and TNF, and the recipients of PTX-pretreated grafts had lower levels of TNF and AST 3 hours after transplantation. The current data indicate that O2- and TNF production in liver grafts is suppressed by PTX pretreatment. Through its suppressive effect on Kupffer cells, PTX may help minimize preservation-reperfusion injury and improve graft survival.

Effects of pentoxifylline pretreatment on kupffer cells in rat liver transplantation

Previous research with pentoxifylline (PTX), a methylxanthine phosphodiesterase inhibitor, suggests that this drug may be capable of suppressing the activation of Kupffer cells and thereby help decrease liver injury after transplantation. To investigate this possibility, the current study sought to determine whether the release of O 2 − and tumor necrosis factor (TNF) from Kupffer cells in donor livers can be suppressed if the organs are exposed to PTX before preservation. In an in vitro experiment, rat livers were flushed with PTX (25 mg/kg body weight) in University of Washington (UW) solution or UW solution alone (control) and then and stored in UW solution for either 4 or 24 hours. Kupffer cells then were purified and their degree of activation determined by measuring O 2 − release and the production of TNF after lipopolysaccharide stimulation. In an in vivo experiment, a group of rats underwent orthotopic liver transplantation with grafts prepared in the same manner as in the in vitro study. TNF and aspartate transaminase (AST) were measured in blood samples taken 3 hours and 24 hours after transplantation. Compared with controls, the Kupffer cells from grafts pretreated with PTX produced significantly less 2 − and TNF, and the recipients of PTX-pretreated grafts had lower levels of TNF and AST 3 hours after transplantation. The current data indicate that O 2 − and TNF production in liver grafts is suppressed by PTX pretreatment. Through its suppressive effect on Kupffer cells, PTX may help minimize preservation-reperfusion injury and improve graft survival.

Role of platelets in hepatic allograft preservation injury in the rat

Cold preservation of liver allografts injuries hepatic sinusoidal lining cells. This injury is exacerbated on reperfusion, in part because of adhesion of leukocytes. Platelets also adhere to activated endothelial surfaces. In this study we examined the role of platelets in preservation injury. Our specific aim was to determine whether the degree of platelet adhesion on reperfusion of preserved rat livers was related to duration of cold or warm ischemia and whether platelet adhesion resulted in injury to allografts. We also examined the effect of prior activation of platelets on adhesion and injury. Rat livers were preserved at 1 degree C for different time periods in University of Wisconsin solution and then reperfused for 3 hr on the isolated perfused rat liver system with Krebs-Henseleit solution to which unactivated isolated rat platelets were added. Other livers were rewarmed before reperfusion or reperfused with activated platelets. Platelets were lost from the circulation in all studies; the percentage reduction of circulating platelets was dependent on the length of preservation. The initial platelet concentration did not affect the rate of reduction of platelets in the circuit. Rewarming before reperfusion increased platelet adherence, and prior activation also increased adherence. With electron microscopy we determined that platelets adhered in small aggregates to endothelial cells or endothelial cell remnants. Adherent platelets appeared more activated and contained fewer granules than did unperfused platelets. Liver injury as measured by release of transaminases into perfusate was worsened by longer periods of cold preservation and by addition of rewarming to the protocol. The presence of platelets under these circumstances aggravated injury. Prior activation of platelets also increased the extent of injury. These studies show that platelets have an important role in cold preservation-reperfusion injury.

Lymphocyte adherence in the reperfused rat liver: Mechanisms and effects

Leukocyte adhesion may play a central role in the pathogenesis of preservation-reperfusion injury to liver grafts. We previously showed that lymphocyte adhesion to sinusoids is dependent on the length of cold ischemia. In the present study we examined the mechanisms of lymphocyte adherence after harvesting combined with a short and a long preservation time. The effects of lymphocyte adherence on liver function were also examined. Rat livers were stored at 1°C in University of Wisconsin solution for 45 min or 30 hr and then reperfused at 37°C in the isolated perfused rat liver with isogeneic lymphocytes in an asanguineous perfusate. The role of reactive oxygen intermediates was investigated with allopurinol, a vitamin E analog and ascorbate or superoxide dismutase and catalase. For us to determine the role of Kupffer cells, Kupffer cell blockade was produced by gadolinium chloride. Leukotriene B4 effects were examined with the lipooxygenase inhibitor, nordihydroguaiaretic acid. We evaluated the possible presence of mechanical obstruction by studying flow rates and the circulation of red blood cells. We examined the role of adhesion molecules by pretreating lymphocytes with trypsin or neuraminidase and by exposing livers to arabinogalactan. We investigated the effects of lymphocyte adhesion on liver function by comparing perfusate liver enzymes in livers reperfused with and without lymphocytes, with trypsinized lymphocytes and with an increased number of lymphocytes. Allopurinol significantly reduced hypoxanthine degradation, and nordihydroguaiaretic acid inhibited leukotriene B4 release into the perfusate. The ability of gadolinium chloride to inhibit Kupffer cells was shown by colloid carbon uptake. In livers harvested and preserved for 45 min, lymphocytes decreased about 40% during reperfusion. In livers preserved for 30 hr, the reduction was significantly greater (about 80%). Lymphocyte adherence was lessened in livers preserved for 45 min by all three of the reactive oxygen intermediate protectants and by gadolinium chloride. In contrast, neither reactive oxygen intermediate protectants nor gadolinium chloride reduced adherence in livers preserved for 30 hr. Nordihydroguaiaretic acid had no effect in livers preserved for either 45 min or 30 hr. Portal flow in livers preserved for 45 min and 30 hr was similar, suggesting an absence of mechanical obstruction, and this finding was supported by a complete absence of red cell trapping. Trypsinization of lymphocytes and exposure of livers to arabinogalactan significantly lessened lymphocyte adherence in livers preserved for 30 hr but not in those preserved for 45 min. Pretreatment with neuraminidase significantly increased adherence in livers preserved for 30 hr. Finally, the presence of lymphocytes in the circuit significantly increased liver enzymes in livers preserved for 30 hr, unless the cells were trypsinized. The use of an increased number of lymphocytes increased perfusate transaminase levels. In livers preserved for 45 min, the release of liver enzymes was much lower and was not affected by the presence of lymphocytes. The results of this study demonstrate the existence of two distinct mechanisms of adhesion, one operative after harvesting and a short period of preservation and another operative after longer periods. Lymphocytes have deleterious effects on the reperfusion of livers stored for a prolonged period. (HEPATOLOGY 1993;17:131–142.)

Lymphocyte Adherence in the Reperfused Rat Liver: Mechanisms and Effects

Leukocyte adhesion may play a central role in the pathogenesis of preservation-reperfusion injury to liver grafts. We previously showed that lymphocyte adhesion to sinusoids is dependent on the length of cold ischemia. In the present study we examined the mechanisms of lymphocyte adherence after harvesting combined with a short and a long preservation time. The effects of lymphocyte adherence on liver function were also examined. Rat livers were stored at 1 degrees C in University of Wisconsin solution for 45 min or 30 hr and then reperfused at 37 degrees C in the isolated perfused rat liver with isogeneic lymphocytes in an asanguineous perfusate. The role of reactive oxygen intermediates was investigated with allopurinol, a vitamin E analog and ascorbate or superoxide dismutase and catalase. For us to determine the role of Kupffer cells, Kupffer cell blockade was produced by gadolinium chloride. Leukotriene B4 effects were examined with the lipooxygenase inhibitor, nordihydroguaiaretic acid. We evaluated the possible presence of mechanical obstruction by studying flow rates and the circulation of red blood cells. We examined the role of adhesion molecules by pretreating lymphocytes with trypsin or neuraminidase and by exposing livers to arabinogalactan. We investigated the effects of lymphocyte adhesion on liver function by comparing perfusate liver enzymes in livers reperfused with and without lymphocytes, with trypsinized lymphocytes and with an increased number of lymphocytes. Allopurinol significantly reduced hypoxanthine degradation, and nordihydroguaiaretic acid inhibited leukotriene B4 release into the perfusate. The ability of gadolinium chloride to inhibit Kupffer cells was shown by colloid carbon uptake. In livers harvested and preserved for 45 min, lymphocytes decreased about 40% during reperfusion. In livers preserved for 30 hr, the reduction was significantly greater (about 80%). Lymphocyte adherence was lessened in livers preserved for 45 min by all three of the reactive oxygen intermediate protectants and by gadolinium chloride. In contrast, neither reactive oxygen intermediate protectants nor gadolinium chloride reduced adherence in livers preserved for 30 hr. Nordihydroguaiaretic acid had no effect in livers preserved for either 45 min or 30 hr. Portal flow in livers preserved for 45 min and 30 hr was similar, suggesting an absence of mechanical obstruction, and this finding was supported by a complete absence of red cell trapping. Trypsinization of lymphocytes and exposure of livers to arabinogalactan significantly lessened lymphocyte adherence in livers preserved for 30 hr but not in those preserved for 45 min.(ABSTRACT TRUNCATED AT 400 WORDS)

Preservation-reperfusion injury, primary graft non-function and tumour necrosis factor

The evolution of orthotopic liver transplantation from an experimental procedure to its present widespread role has been made possible by advances in hypothermic organ preservation techniques. The time that the organ spends in limbo from hepatectomy to reperfusion is balanced between the need to transfer organs to donors at distant sites and the liver damage resulting from prolonged ischaemia. Realistic storage times of up to 24 h are possible following the introduction of University of Wisconsin (UW) storage solution (1,2). However, primary non-function still occurs in up to 10% of grafts and liver damage as a result of the preservation process remains a clinical problem. Preservation-reperfusion injury is the result of graft ischaemia modified by the cooling process the extent of injury is essentially dependent upon the duration of cold ischaemia (3). Although many of the mechanisms remain poorly understood (for a recent detailed review, see Ref. 4), the weak link in the chain appears to be the sinusoidal endothelial cell lining, with damage to these cells resulting in disturbance of the hepatic microcirculation and subsequent graft failure. Cold ischaemia is damaging to some extent to all cells. Metabolic processes continue, albeit at a slow rate, resulting in reduced ATP levels (5) and intracellular acidosis (6); inhibition of NA+/K+-ATPase causes Na + influx and cell swelling. In hepatocytes xanthine oxidase accumulates during the period of cold ischaemia on reperfusion this results in the production of toxic reactive oxygen intermediates (7). In animal models the earliest morphological changes in liver are seen in sinusoidal endothelial cells, with widening of fenestrations followed by withdrawal of cell processes after 4-8 hours cold ischaemia (3). Following reperfusion there is morphological evidence of Kupffer cell activation, rounding of sinusoidal endothelial cells (3), and adherence of lymphocytes to the endothelium (8).