Reduced-size Orthotopic Liver Transplantation Research Articles

Losartan activates sirtuin 1 in rat reduced-size orthotopic liver transplantation

To investigate a possible association between losartan and sirtuin 1 (SIRT1) in reduced-size orthotopic liver transplantation (ROLT) in rats. Livers of male Sprague-Dawley rats (200-250 g) were preserved in University of Wisconsin preservation solution for 1 h at 4 °C prior to ROLT. In an additional group, an antagonist of angiotensin II type 1 receptor (AT1R), losartan, was orally administered (5 mg/kg) 24 h and 1 h before the surgical procedure to both the donors and the recipients. Transaminase (as an indicator of liver injury), SIRT1 activity, and nicotinamide adenine dinucleotide (NAD(+), a co-factor necessary for SIRT1 activity) levels were determined by biochemical methods. Protein expression of SIRT1, acetylated FoxO1 (ac-FoxO1), NAMPT (the precursor of NAD+), heat shock proteins (HSP70, HO-1) expression, endoplasmic reticulum stress (GRP78, IRE1α, p-eIF2) and apoptosis (caspase 12 and caspase 3) parameters were determined by Western blot. Possible alterations in protein expression of mitogen activated protein kinases (MAPK), such as p-p38 and p-ERK, were also evaluated. Furthermore, the SIRT3 protein expression and mRNA levels were examined. The present study demonstrated that losartan administration led to diminished liver injury when compared to ROLT group, as evidenced by the significant decreases in alanine aminotransferase (358.3 ± 133.44 vs 206 ± 33.61, P < 0.05) and aspartate aminotransferase levels (893.57 ± 397.69 vs 500.85 ± 118.07, P < 0.05). The lessened hepatic injury in case of losartan was associated with enhanced SIRT1 protein expression and activity (5.27 ± 0.32 vs 6.08 ± 0.30, P < 0.05). This was concomitant with increased levels of NAD(+) (0.87 ± 0.22 vs 1.195 ± 0.144, P < 0.05) the co-factor necessary for SIRT1 activity, as well as with decreases in ac-FoxO1 expression. Losartan treatment also provoked significant attenuation of endoplasmic reticulum stress parameters (GRP78, IRE1α, p-eIF2) which was consistent with reduced levels of both caspase 12 and caspase 3. Furthermore, losartan administration stimulated HSP70 protein expression and attenuated HO-1 expression. However, no changes were observed in protein or mRNA expression of SIRT3. Finally, the protein expression pattern of p-ERK and p-p38 were not altered upon losartan administration. The present study reports that losartan induces SIRT1 expression and activity, and that it reduces hepatic injury in a ROLT model.

The use of a reversible proteasome inhibitor in a model of Reduced-Size Orthotopic Liver transplantation in rats

Ischemia/reperfusion injury (IRI), inherent in liver transplantation (LT), is the main cause of initial deficiencies and primary non-function of liver allografts. Living-related LT was developed to alleviate the mortality resulting from the scarcity of suitable deceased grafts. The main problem in using living-related LT for adults is graft size disparity. In this study we propose for the first time that the use of a proteasome inhibitor (Bortezomib) treatment could improve liver regeneration and reduce IRI after Reduced-Size Orthotopic Liver transplantation (ROLT). Rat liver grafts were reduced by removing the left lateral lobe and the two caudate lobes and preserved in UW or IGL-1 preservation solution for 1h liver and then subjected to ROLT with or without Bortezomib treatment. Our results show that Bortezomib reduces IRI after LT and is correlated with a reduction in mitochondrial damage, oxidative stress and endoplasmic reticulum stress. Furthermore, Bortezomib also increased liver regeneration after reduced-size LT and increased the expression of well-known ischemia/reperfusion protective proteins such as nitric oxide synthase, heme oxigenase 1 (HO-1) and Heat Shock Protein 70. Our results open new possibilities for the study of alternative therapeutic strategies aimed at reducing IRI and increasing liver regeneration after LT. It is hoped that the results of our study will contribute towards improving the understanding of the molecular processes involved in IRI and liver regeneration, and therefore help to improve the outcome of this type of LT in the future.

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.

Feasibility of Reduced-size Orthotopic Liver Transplantation with Fatty Grafts and its Potential Regeneration in Rats

We undertook this study to determine the minimum necessary volume of various grades of fatty liver grafts in reduced-size orthotopic liver transplantation (ROLT) and to elucidate the property of fatty liver regeneration. By modified two-cuff technique, ROLT of different rats was performed with various grades and volumes of fatty liver grafts. The survival rate, graft-to-recipient body weight ratio (GRWR), standard liver volume (SLV) and liver function were detected to determine appropriate steatotic grafts that could be safely adopted in ROLT. In grade II macrovesicular steatosis (MaS) grafts, the 1-week survival rate of 70% ROLT was significantly worse (25%). In grafts with microvesicular steatosis (MiS) undergoing 70%, 60%, and 50% ROLT, 7-day survival decreased according to the graft volume (75%, 75%, and 33.3%). Proliferating cell nuclear antigen (PCNA) and 5-bromo-2'-deoxyuridine (BrdU) labeling index in normal liver graft reached the highest on postoperative day (POD) 3, whereas in fatty grafts the expression peak was on POD 7. Liver regeneration ratios of normal liver graft were higher than mild MaS graft, but grade II MaS grafts hardly regenerated. When compared with moderate MaS grafts B2 (70% ROLT) and mild MaS grafts A3 (60%) groups, the disparities of alanine aminotransferase and total bilirubin were significant. In successful and long-term survival of rat ROLT, MiS or grade II MaS livers could be safely used as grafts only when their GRWR >2.29+/-0.20 (or 2.28+/-0.12) % and SLV >60%; MaS livers in grade II should not be used as grafts. Hepatic regeneration potential of mild MaS or MiS with any grade graft is not obviously impaired after ROLT, but delayed proliferative peak and prolonged cell proliferative cycle are shown.

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.

Protection against lung damage in reduced-size liver transplantation*

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. Randomized and controlled animals study. Experimental laboratory. Male Sprague-Dawley rats. Lung damage was evaluated in ROLT with or without preconditioning. Nitric oxide and interleukin (IL)-1 actions were altered pharmacologically. IL-1, tumor necrosis factor (TNF)-alpha, 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-1alpha 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-1alpha and lung damage, reduced systemic sTNFR2 and increased free TNF levels. These injurious effects were avoided when IL-1 action was inhibited. 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.

How ischaemic preconditioning protects small liver grafts

Interleukin-1 (IL-1) and transforming growth factor-beta (TGFbeta) 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 TGFbeta 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 TGFbeta 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.

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.

Effects of deletion variant of hepatocyte growth factor on reduced-size liver transplantation in rats.

The deletion variant of hepatocyte growth factor (dHGF) exerts mitogenic and antifibrotic effects. The purpose of this study was to evaluate the effect of dHGF on rats that had undergone syngeneic or allogeneic reduced-size (60%) orthotopic liver transplantation (ROLT). Starting immediately after the syngeneic (Lewis to Lewis) and allogeneic (Lewis to Brown Norway) ROLT, 500 microg/kg dHGF was administered i.v. twice a day until the day the rats were killed. Its effect on hepatic graft weight, regeneration, and biochemical parameters was evaluated. dHGF promoted restoration of the liver volume and liver regeneration as well as protein synthesis in the rats that underwent syngeneic ROLT. In the rats that underwent allogeneic ROLT, dHGF reduced the level of serum cytosolic enzymes related to acute cellular rejection, but a significant improvement in liver regeneration and protein synthesis was not seen. When tacrolimus was administered to prevent rejection of the allogeneic grafts, the beneficial effect of dHGF was apparent, and was as beneficial as in syngeneic ROLT. Administering dHGF after liver transplantation augments the regeneration and functional recovery of partial liver grafts and reduces hepatocyte injury in acute cellular rejection.

Split-liver transplantation: One plus one doesn't always equal two

Surgical reduction of donor livers to treat small children has been performed successfully in several centers. While this procedure improves the allocation of livers, it does not increase the organ supply. We have extended reduced-size orthotopic liver transplantation (OLT) to treat 18 patients with 9 livers, accounting for 26% of our transplants during a 10-month period and have evaluated the results. In 18 split liver OLTs, patient survival was 67% and graft survival was 50%. In comparison, for 34 patients treated with full-size OLT during the same period, patient survival was 84% (p = 0.298) and graft survival was 76% (p = 0.126). Biliary complications were significantly more frequent in split grafts, occurring in 27%, as compared to 4% in full-sized grafts (p = 0.017). Primary nonfunction (4% versus 5.5%) and arterial thrombosis (6% versus 9%) occurred with similar frequency in split and full-size OLT (p = not significant). These results demonstrated that split-liver OLT is feasible and could have a substantial impact in transplant practice. We believe that biliary complications can be prevented by technical improvements and that split-liver OLT will improve transplant therapy by making more livers available. The University of Chicago program in pediatric liver transplantation continues actively to seek innovative surgical solutions to problems related to the management of children with end-stage liver disease. Among the most important problems facing these children is a shortage of donor organs, which results from three factors in addition to the actual supply of pediatric donors: the concentration of pediatric liver disease in the population younger than 2 years; the necessity for a graft that is small enough; and the epidemiology of accidents and other events that lead to organ donation. Transplantation using a liver love as a graft overcomes size disparity and shifts the available supply of organs fromolder donors to tounger recipients. This work describes the technical aspects of recent innovations in the use of liver lobes in pediatric transplantation, simple reduced-size liver transplantation (RLT), split-liver transplantation (SLT), orthotopic auxiliary liver grafting (ALT), and transplantation using a living related donor (LRLT), and compares their results. Since November 1986 a total of 61 procedures have been performed in which a liver lobe was used as a graft: 26 RLT;30 SLT,25 in children and 5 in adults; 5 LRLT; and 1 ALT. Overall 62% of transplants performed in children have involved using a liver lobe as a graft. The rates of ccomplications are somewhat higher than with whole-liver transplantation, but this may not be entirely the result of the complex procedures. Split liver transplantation is associated with complications in donors and recipients, but to date survival is 100%. Orthotopic auxillary liver transplatation effectively corrected the metabolic defect n one patient with ornithine transcarbamylase deficiency. Overall the various modalities of using graft reduction have reduction have resulted in postoperative results similar to those aachieved with full-size grafts, while pretransplantation mortality has been limited to less than 2%. Thous the use of grafts as liver lobes accomplisshes the goal of reducing global mortality among children with end-stage liver disease, but at the cost of increased surgical complexity and more postoperative complications.

The Use of Reduced-Size Liver Transplants in Children, Including Split Livers and Living Related Liver Transplants

One of the key problems facing children awaiting liver transplantation is the shortage of donor organs. Surgical procedures that address this problem include: reduced-size liver transplantation (RLT), split liver transplantation (SLT), and living related liver transplantation (LRLT). RLT makes more of the current donor pool accessible to the pediatric recipient. SLT furnishes 2 liver grafts from 1 cadaveric donor, and LRLT provides an innovative supply of donor organs. This report compares the results achieved with RLT, SLT, and LRLT to those seen with full-size orthotopic liver transplantation (OLT). Between November 1984 and February 1991, 457 liver transplants were performed at the University of Chicago. Two hundred fourteen of these transplants were placed into recipients less than 13 years of age. Of these 214 pediatric orthotopic liver transplants (OLT), 103 were full-size livers and 111 were some type of reduced graft (RLT, SLT, or LRLT). There were 57 RLT, 34 SLT, and 20 LRLT. The recipients of the reduced grafts (RLT, SLT, or LRLT) averaged 1.9 +/- 1.8 years of age and 9.6 +/- 6.4 kg compared to the recipients of the full-size livers who averaged 3.5 +/- 3.4 years of age and 14.1 +/- 8.8 kg (p = 0.0001). The most common indication for transplantation was biliary atresia (105 patients). Overall patient survival after primary full-size OLT was 71.8%. Reduced-size OLT (RLT, SLT, and LRLT) resulted in an overall patient survival of 72.6% after primary transplantation. Patient survivals for primary transplants with specific types of reduced-size grafts were: RLT 76.5% (after RLT was used routinely), SLT 66.7%, and LRLT 89.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Transplantation of Two Patients with One Liver

Surgical reduction of donor livers to treat small children has been performed successfully in several centers. While this procedure improves the allocation of livers, it does not increase the organ supply. We have extended reduced-size orthotopic liver transplantation (OLT) to treat 18 patients with 9 livers, accounting for 26% of our transplants during a 10-month period and have evaluated the results. In 18 split liver OLTs, patient survival was 67% and graft survival was 50%. In comparison, for 34 patients treated with full-size OLT during the same period, patient survival was 84% (p = 0.298) and graft survival was 76% (p = 0.126). Biliary complications were significantly more frequent in split grafts, occurring in 27%, as compared to 4% in full-sized grafts (p = 0.017). Primary nonfunction (4% versus 5.5%) and arterial thrombosis (6% versus 9%) occurred with similar frequency in split and full-size OLT (p = not significant). These results demonstrated that split-liver OLT is feasible and could have a substantial impact in transplant practice. We believe that biliary complications can be prevented by technical improvements and that split-liver OLT will improve transplant therapy by making more livers available.

Reduced-size orthotopic liver transplantation: use in the management of children with chronic liver disease.

Reducing the size of a liver for use in a recipient smaller than the donor is one way to reduce mortality before orthotopic liver transplantation in children because of the scarcity of pediatric organ donors. In this report, we review the results of this approach over the past 2 years, during which we have used reduced-size orthotopic liver transplantation routinely in small children. Forty-nine children underwent orthotopic liver transplantation between September, 1986, and October, 1988; orthotopic liver transplantation with a whole organ (full-size orthotopic liver transplantation) was performed in 36 children, whereas 13 patients received reduced-size orthotopic liver transplantation. In two pairs of patients, the reduced grafts were obtained from single donors, using a "split-liver" procedure. All grafts were implanted in the orthotopic position following total recipient hepatectomy. The preoperative diagnostic categories were not significantly different between groups. Patients receiving reduced-size orthotopic liver transplantation were younger (1.6 +/- 1.5 vs. 4.4 +/- 4.6 years), and a higher percentage were in the intensive care unit prior to transplant (31 vs. 9%). Thirty of 36 (82%) patients receiving full-size orthotopic liver transplantation and 10 of 13 (77%) patients receiving reduced-size orthotopic liver transplantation are alive 3 to 27 months after transplantation. The rates of retransplantation were 24% for full-size orthotopic liver transplantation and 15% for reduced-size orthotopic liver transplantation. Despite the greater complexity of reduced-size orthotopic liver transplantation and the higher frequency of critically ill recipients selected for the procedure, the results of reduced-size orthotopic liver transplantation are comparable with full-size orthotopic liver transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)