Rosa Franco-Gou

Preservation of Steatotic Livers in IGL-1 Solution

A new Institut Georges Lopez (IGL‐1) solution was used to preserve steatotic livers. Steatotic (obese [Ob]) and nonsteatotic (lean [Ln]) livers from Zücker rats (n = 16, 8 Ln and 8 Ob) were preserved for 24 hours at 4°C in University of Wisconsin (UW) or IGL‐1 solution, respectively, and then perfused ex vivo for 2 hours at 37°C. Additionally, Ob and Ln livers (n = 16, 8 Ln and 8 Ob) were preserved in IGL‐1 plus Nω‐nitro‐L‐arginine methyl ester hydrochloride (L‐NAME). Hepatic injury and function (aminotransferases, bile production, bromosulfophthalein clearance), and factors potentially involved in the susceptibility of steatotic livers to ischemia‐reperfusion injury, such as oxidative stress, mitochondrial damage, and vascular resistance, were studied. Nitric oxide (NO) production and constitutive and inducible NO synthase were also measured. Steatotic and nonsteatotic livers preserved in IGL‐1 solution showed lower transaminases, malondialdehyde, glutamate dehydrogenase levels, and higher bile production than UW‐solution‐preserved livers. IGL‐1 solution protected against oxidative stress, mitochondrial damage and the alterations in vascular resistance associated with cold ischemia‐reperfusion. Thus, at the end of reperfusion period, aspartate aminotransferase levels in steatotic livers were 281 ± 6 U/L in UW vs. 202 ± 10 U/L in IGL‐1 solution. Glutamate dehydrogenase was 463 ± 75 U/L in UW vs. 111 ± 4 U/L in IGL‐1 solution, and oxidative stress was 3.0 ± 0.1 nmol/mg prot in UW vs. 2.0 ± 0.1 nmol/mg prot in IGL‐1 solution. These beneficial effects of IGL‐1 solution were abolished by the addition of L‐NAME, which implicates NO in the benefits of IGL‐1. In conclusion, IGL‐1 solution provided steatotic livers with better protection against the deleterious effects of cold ischemia‐reperfusion injury than did UW solution. Liver Transpl 12:1215‐1223, 2006.

How ischaemic preconditioning protects small liver grafts

Interleukin‐1 (IL‐1) and transforming growth factor‐β (TGFβ) are key inhibitors of hepatocyte proliferation after hepatectomy. IL‐1 inhibition by heat shock proteins (HSPs) has been reported in inflammatory processes. A recent study indicated the benefits of ischaemic preconditioning in reduced‐size orthotopic liver transplantation (ROLT). The present study examined: (a) the effect of ischaemic preconditioning on IL‐1 and TGFβ in ROLT; (b) whether preconditioning protects small liver grafts through HSP induction; and (c) whether the potential benefits of preconditioning on HSP is related to IL‐1 inhibition. Our results, obtained with an IL‐1 receptor antagonist, indicated the injurious effects of IL‐1 in ischaemia‐reperfusion (I/R) injury and established a relationship between IL‐1 and growth factors. Thus, IL‐1 reduced hepatocyte growth factor (HGF) and promoted TGFβ release, thus contributing to the impaired liver regeneration associated with ROLT. Preconditioning inhibited IL‐1 through nitric oxide (NO), thereby protecting against the injurious effects of IL‐1. In addition, by another pathway independent of NO, preconditioning induced HSP70 and haem‐oxygenase‐1 (HO‐1). HO‐1 protected against I/R injury and liver regeneration, whereas the benefits resulting from HSP70 were mainly related to hepatocyte proliferation. These results suggest a mechanism that explains the effectiveness of preconditioning in ROLT. They suggest, too, that other strategies, in addition to preconditioning, that modulate IL‐1 and/or HSPs could be considered in clinical situations requiring liver regeneration such as small liver grafts. Copyright

Protection of Reduced‐Size Liver for Transplantation

The shortage of available organs for liver transplantation has motivated the development of new surgical techniques such as reduced‐size liver transplantation. Ischemia‐reperfusion (I/R) associated with liver transplantation impairs liver regeneration. Ischemic preconditioning is effective against I/R injury in clinical practice of liver tumour resections. The present study evaluated the effect of ischemic preconditioning on reduced‐size liver for transplantation and attempted to identify the underlying protective mechanisms. Hepatic injury and regeneration (transaminases, proliferating cell nuclear antigen [PCNA] labeling index, and hepatocyte growth factor [HGF]) were assessed after reduced‐size orthotopic liver transplantation (ROLT). Energy metabolism, oxidative stress, tumor necrosis factor‐α (TNF) and interleukin‐6 (IL‐6) were examined as possible mechanisms involved in liver regeneration. Ischemic preconditioning reduced transaminase levels and increased HGF levels and the percentage of PCNA‐positive hepatocytes after ROLT. This was associated with a decrease in oxidative stress following ROLT, whereas energy metabolism and hepatic IL‐6 and TNF release were unchanged. The benefits of ischemic preconditioning on hepatic injury and liver regeneration could be mediated, at least partially by nitric oxide. These results suggest a new potential application of ischemic preconditioning in reduced‐size liver transplantation.

New preservation strategies for preventing liver grafts against cold ischemia reperfusion injury

Background:  In spite of improvements in University of Wisconsin (UW) preservation solution, the injury from grafts during cold storage is an unresolved problem in liver transplantation. The aim of the present study was to evaluate the beneficial effect on ischemia–reperfusion injury associated with liver transplantation of the inversion of K+ and Na+ concentrations and the replacement of hydroxyethyl starch (HES) by polyethylene glycol (PEG) in UW preservation solution.

Matrix metalloproteinase 2 in reduced-size liver transplantation: beyond the matrix.

We studied the contribution of matrix metalloproteinase 2 (MMP2) and matrix metalloproteinase 9 (MMP9) to the beneficial effects of preconditioning (PC) in reduced‐size orthotopic liver transplantation (ROLT). We also examined the role of c‐Jun N‐terminal kinase (JNK) and whether it regulates MMP2 in these conditions. Animals were subjected to ROLT with or without PC and pharmacological modulation, and liver tissue samples were then analyzed. We found that MMP2, but notMMP9, is involved in the beneficial effects of PC in ROLT. MMP2 reduced hepatic injury and enhanced liver regeneration. Moreover, inhibition of MMP2 in PC reduced animal survival after transplantation. JNK inhibition in the PC group decreased hepatic injury and enhanced liver regeneration. Furthermore, JNK upregulated MMP2 in PC. In addition, we showed that Tissue inhibitors of matrix metalloproteinases 2 (TIMP2) was also upregulated in PC and that JNK modulation also altered its levels in ROLT and PC. Our results open up new possibilities for therapeutic treatments to reduce I/R injury and increase liver regeneration after ROLT, which are the main limitations in living‐donor transplantation.

Effect of Angiotensin II and Bradykinin Inhibition in Rat Reduced-Size Liver Transplantation

This study examined whether angiotensin II (Ang II) blockers [Ang II type I receptor antagonist, Ang II type II receptor antagonist, and angiotensin converting enzyme (ACE) inhibitor] could reduce hepatic injury and improve regeneration in reduced‐size orthotopic liver transplantation (ROLT) and whether the beneficial effects of ischemic preconditioning (PC) in ROLT could be explained by changes in Ang II. We show that small liver grafts generated Ang II after ROLT and that this was associated with increased angiotensinogen and ACE messenger RNA expression. Furthermore, inhibition of Ang II did not contribute to PC‐induced protection in ROLT. All Ang II blockers reduced hepatic injury, but none of them promoted liver regeneration. Bradykinin (BK) receptor antagonist improved liver regeneration but did not reduce hepatic injury in ROLT. Finally, the combination of Ang II blockers and BK receptor antagonists in ROLT reduced hepatic injury and improved liver regeneration. In conclusion, treatments with either Ang II blockers or BK receptor antagonists cannot, on their own, improve the outcome of ROLT. Although Ang II blockers can reduce hepatic ischemia‐reperfusion injury and BK receptor antagonists can promote liver regeneration, neither confers both benefits at the same time. Consequently, it may be of clinical interest to apply both treatments simultaneously. Liver Transpl 15:313–320, 2009.

Protection against lung damage in reduced-size liver transplantation.

Objective:This study examined the effect of ischemic preconditioning on pulmonary damage associated with reduced-size orthotopic liver transplantation (ROLT) and attempted to identify the underlying protective mechanisms. Design:Randomized and controlled animals study. Setting:Experimental laboratory. Subjects:Male Sprague-Dawley rats. Interventions:Lung damage was evaluated in ROLT with or without preconditioning. Nitric oxide and interleukin (IL)-1 actions were altered pharmacologically. Measurements and Main Results:IL-1, tumor necrosis factor (TNF)-α, soluble TNF receptors (sTNFR), and inflammatory response in lung were measured after ROLT. Our results indicate the involvement of IL-1 in the lung damage following ROLT. Ischemic preconditioning, mediated by nitric oxide, reduced IL-1 release and protected against lung damage. Nitric oxide synthesis inhibition in the preconditioned group led to increased IL-1 levels and increased lung damage following ROLT, whereas the addition of IL-1 receptor antagonist protected against the injurious effects of nitric oxide inhibition. In addition, nitric oxide pretreatment gave similar results in terms of IL-1α and lung protection to those found in preconditioning. The benefits to the lung attributable to IL-1 inhibition might be linked to the effect of this cytokine on sTNFR, an endogenous mechanism that modulates systemic TNF actions. In fact, strategies aimed at inhibiting IL-1 action, including IL-1 receptor antagonist, ischemic preconditioning, and nitric oxide donor, increased systemic sTNFR2 and decreased free TNF, following ROLT. Similarly, nitric oxide synthesis inhibition in the preconditioned group, which increased IL-1α and lung damage, reduced systemic sTNFR2 and increased free TNF levels. These injurious effects were avoided when IL-1 action was inhibited. Conclusions:Ischemic preconditioning and pharmacologic strategies that simulate its benefits protected against lung damage in an experimental model of ROLT. Our results also suggest a potential relationship between nitric oxide, IL-1, and TNF/sTNF in the benefits of preconditioning on the lung damage associated with ROLT.

Síndrome de isquemia-reperfusión asociado al trasplante hepático: una visión actualizada

Ischemia-reperfusion (I/R) injury is the main cause of both initial graft dysfunction and primary failure in liver transplantation. The search for therapeutic strategies to prevent I/R injury has led to research into promising drugs, although most have not been used clinically. Gene therapy requires better transfection techniques, avoiding vector toxicity, and ethical debate before being used clinically. Ischemic preconditioning is the first therapeutic strategy used in clinical practice to reduce I/R injury in hepatectomies for tumors. Future research will provide data on the effectiveness of ischemic preconditioning in reducing I/R injury associated with liver transplantation, and in reducing the vulnerability of steatotic grafts to I/R syndrome so that they can be used in transplantation, thus relieving the organ shortage.