he goal of liver preservation during transplant surgery is to maintain cellular viability, to allow T early resumption of normal cellular metabolism on reperfusion, and thus to avoid the potential morbidity and mortality associated with poor graft function. The major tool used for liver preservation today is cold organ storage, which reduces metabolic activity by lowering the temperature to between 1 to 4°C.'To accomplish organ protection during prolonged cold ischemia different cold-storage solutions were designed. Belzer's and Southard's University of Wisconsin (UW) solution has been successfully used worldwide since the first clinical use in 1987. This complex solution supports good graft function even after extended cold preservation.2 The preservation principles of the U W solution are based on the prevention of liver-specific cellular features occurring during cold ischemia. Intracellular edema is prevented by adding nonmetabolizable impermeants such as lactobionate and raffinose. The colloid, hydroxyethyl starch, suppresses expansion of extracellular space.The solution contains no glucose to avoid intracellular acidosis and it contains the hydrogen ion buffer KH2P04. Glutathione and allopurinol are added to prevent injury by oxygen radicals. Allopurinol, a xanthine oxidase inhibitor, can also salvage adenosine triphosphate (ATP) precursors. The purine nucleotide pool for ATP synthesis is further supported by adding adenosine. ' Another solution, Bretschneider's histidine-tryptophan-ketoglutarate (HTK), was designed for cardiac preservation and it was formulated to retard acidosis Although the preservation potential of liver cold storage solutions has significantly improved, graft dysfunction after transplantation still occurs at a rate of 5% to 2O%.* A considerable part of primary graft dysfunction is attributable to inadequate cold storage, including an imperfect storage solution. Graft dysfunction results in increased mortality and morbidity rates.5 Subsequent retransplantations further enhance the demands on the short list of donor organs. Thus, new strategies to increase organ protection during cold preservation are still urgently needed.Cold ischemia-reperfusion injury of liver is a complex of various events that virtually affect all types of hepatic cells. Generally, characteristic features of ischemic cell injury are triggered by ATP depletion,GJ impairment of mitochondria1 respiratory function,8,9 and acidosis from glycolysis.10 Liver parenchymal cells are highly metabolically active and represent the majority (approximately SO%) of liver volume. * This could lead to the assumption that after cold ischemia liver function deteriorates mainly through affected hepatocytes. Hepatocytes, however, are known to be only minimally affected by cold storage. l 2Cold preservation of the liver followed by reperfusion results in loss of viability of sinusoidal endothelial cells (SEC) characterized morphologically by denudation and detachment of the endotheli~m.'~>'3 Disruption of the endothelial wall leads to...

The aim of this study was to evaluate whether the protective effect of intermittent clamping and ischemic preconditioning is related to an improved hepatic microcirculation after ischemia/reperfusion injury. Male C57BL/6 mice were subjected to 75 or 120 min of hepatic ischemia and 1 or 3 hours of reperfusion. The effects of continuous ischemia, intermittent clamping, and ischemic preconditioning before prolonged ischemia on sinusoidal perfusion, leukocyte-endothelial interactions, and Kupffer cell phagocytic activity were analyzed by intravital fluorescence microscopy. Kupffer cell activation was measured by tissue levels of tumor necrosis factor (TNF)-␣, and the integrity of sinusoidal endothelial cells and Kupffer cells were evaluated by electron microscopy. Continuous ischemia resulted in decreased sinusoidal perfusion rate and phagocytic activity of Kupffer cell, increased leukocyteendothelial interactions and TNF-␣ levels. Both protective strategies improved sinusoidal perfusion, leukocyteendothelial interactions and phagocytic activity of Kupffer cells after 75-minutes of ischemia, and intermittent clamping also after 120 minutes ischemia. TNF-␣ release was significantly reduced and sinusoidal wall integrity was preserved by both protective procedures. In conclusion, both strategies are protective against ischemia/reperfusion injury by maintaining hepatic microcirculation and decreasing Kupffer cell activation for clinically relevant ischemic periods, and intermittent clamping appears superior for prolonged ischemia. (Liver Transpl 2004;10:520-528.)

With increasing time of cold preservation, levels of highenergy nucleotides in the liver are reducing. The authors hypothesized that cold preservation sensitizes hepatocyte function to ischemic injury occurring during graft rewarming and that the injury can be prevented by short-term reperfusion. Rat livers were cold-preserved in University of Wisconsin solution for 0 to 18 hours and ischemically rewarmed for 0 to 45 minutes to simulate the implantation stage of transplantation. Hepatobiliary function was assessed using a blood-free perfusion model. In comparison with controls, neither 18-hour preservation nor 45-minute ischemic rewarming significantly influenced hepatocyte function. Compared with livers subjected to 45-minute ischemic rewarming, livers subjected to 9-hour preservation and 45-minute rewarming, and livers subjected to 18-hour preservation and 45-minute rewarming exhibited, respectively: 3.8 and 24 times reduced bile production, 4.3-and 116-fold decreased taurocholate excretion, and 3.1 and 42 times depressed bromosulfophthalein excretion. Thirty-minute oxygenated warm reperfusion after 9-and 18-hour preservation nearly completely blunted sensitization of hepatocyte function to rewarming ischemia. The authors found that shortterm oxygenated reperfusion restored adenine nucleotides in liver tissue to the values found before organ preservation and that reperfusion with energy substrate containing solutions increased tissue adenosine triphosphate concentration to a higher level than that found before preservation. In conclusion, sensitization of hepatocyte function to rewarming ischemia increases disproportionally with storage time, suggesting that this phenomenon may play a role in graft dysfunctions with increasing liver preservation time. Shortterm oxygenated reperfusion of the liver may protect hepatocyte functions against warm ischemic insult, even after extended preservation. (HEPATOLOGY 2000;32:289-296.) Preservation injury is a major cause of morbidity and mortality in liver transplant recipients. 1 Because hypothermic preservation causes selective liver injuries to nonparenchymal cells, while hepatocytes appear well-preserved, it is currently hypothesized that sinusoidal endothelial-cell impairment, 2-5 microcirculatory disturbances, 6,7 activation of Kupffer cells, [8][9][10] and sinusoidal accumulation of leukocytes 11,12 are major causes of preservation-related graft failure. This hypothesis is strongly supported by a number of studies showing that sinusoidal endothelial cells lose their function with increasing time of cold storage 13-15 and die during a brief period of reperfusion. 16,17 On the other hand, most parameters of hepatocyte function of livers reperfused after 18-or 24-hour cold preservation were found to be comparable with control livers perfused immediately after hepatectomy. [18][19][20] In clinical transplantation, however, several authors identified that during the implantation stage of transplantation, prolonged warm ischemic time (WIT), preferentially influencing hepat...

The mechanisms of liver injury from cold storage and reperfusion are not completely understood. The aim of the present study was to investigate: 1) whether the inactivation of Kupffer cells (KCs) by gadolinium chloride (GadCl) modulates cold ischemia-reperfusion injury of rat liver; and 2) whether cold storage of rat liver involves injury to biliary epithelial cells (BECs). Hepatobiliary function was assessed using an isolated perfused rat liver model. Compared with control livers, in livers subjected to cold storage at 4 degrees C in Euro-Collins solution (EC) for 18 hours or in University of Wisconsin solution (UW) for 48 hours, portal flow was lower and resistance significantly higher, taurocholate (TC) and bromosulfophthalein (BSP) elimination were markedly impaired, bile flow was reduced, and lactate dehydrogenase (LDH) leakage into the perfusate was increased. Pretreatment of rats with GadCl, a selective KC toxicant, abrogated disturbances of the microcirculation in both models, but it did not influence viability and functional parameters of the liver. Most of the parameters studied in livers stored in UW solution for 18 hours were not significantly different from those found in control livers. As to biliary activity of gamma-glutamyl transferase (GGT), as an index of BEC integrity, it was increased with increasing time of cold storage. The reabsorption of glucose from the bile decreased with longer storage time. The results suggest the following: 1) that cold ischemia-reperfusion injury of rat liver is mediated by KC-dependent (hepatic microcirculation) and -independent (parenchymal cell function) mechanisms; and 2) that cold storage of rat liver induces functional impairment of BECs.

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he goal of liver preservation during transplant surgery is to maintain cellular viability, to allow T early resumption of normal cellular metabolism on reperfusion, and thus to avoid the potential morbidity and mortality associated with poor graft function. The major tool used for liver preservation today is cold organ storage, which reduces metabolic activity by lowering the temperature to between 1 to 4°C.'To accomplish organ protection during prolonged cold ischemia different cold-storage solutions were designed. Belzer's and Southard's University of Wisconsin (UW) solution has been successfully used worldwide since the first clinical use in 1987. This complex solution supports good graft function even after extended cold preservation.2 The preservation principles of the U W solution are based on the prevention of liver-specific cellular features occurring during cold ischemia. Intracellular edema is prevented by adding nonmetabolizable impermeants such as lactobionate and raffinose. The colloid, hydroxyethyl starch, suppresses expansion of extracellular space.The solution contains no glucose to avoid intracellular acidosis and it contains the hydrogen ion buffer KH2P04. Glutathione and allopurinol are added to prevent injury by oxygen radicals. Allopurinol, a xanthine oxidase inhibitor, can also salvage adenosine triphosphate (ATP) precursors. The purine nucleotide pool for ATP synthesis is further supported by adding adenosine. ' Another solution, Bretschneider's histidine-tryptophan-ketoglutarate (HTK), was designed for cardiac preservation and it was formulated to retard acidosis Although the preservation potential of liver cold storage solutions has significantly improved, graft dysfunction after transplantation still occurs at a rate of 5% to 2O%.* A considerable part of primary graft dysfunction is attributable to inadequate cold storage, including an imperfect storage solution. Graft dysfunction results in increased mortality and morbidity rates.5 Subsequent retransplantations further enhance the demands on the short list of donor organs. Thus, new strategies to increase organ protection during cold preservation are still urgently needed.Cold ischemia-reperfusion injury of liver is a complex of various events that virtually affect all types of hepatic cells. Generally, characteristic features of ischemic cell injury are triggered by ATP depletion,GJ impairment of mitochondria1 respiratory function,8,9 and acidosis from glycolysis.10 Liver parenchymal cells are highly metabolically active and represent the majority (approximately SO%) of liver volume. * This could lead to the assumption that after cold ischemia liver function deteriorates mainly through affected hepatocytes. Hepatocytes, however, are known to be only minimally affected by cold storage. l 2Cold preservation of the liver followed by reperfusion results in loss of viability of sinusoidal endothelial cells (SEC) characterized morphologically by denudation and detachment of the endotheli~m.'~>'3 Disruption of the endothelial wall leads to...

Determination of ACP, alanine transaminase, and aspartate transaminase activities in the washout solution can be used as a rapid, simple, and cost-effective way for screening liver preservation solutions. The results also suggest that KC were not involved in preservation-induced liver damage.