Molecular pathways of regeneration and repair after liver transplantation

The protective roles of augmenter of liver regeneration in hepatocytes in the non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) occurs in 25% of the global population and manifests as lipid deposition, hepatocyte injury, activation of Kupffer and stellate cells, and steatohepatitis. Predominantly expressed in hepatocytes, the augmenter of liver regeneration (ALR) is a key factor in liver regulation that can alleviate fatty liver disease and protect the liver from abnormal liver lipid metabolism. ALR has three isoforms (15-, 21-, and 23-kDa), amongst which 23-kDa ALR is the most extensively studied. The 23-kDa ALR isoform is a sulfhydryl oxidase that resides primarily in the mitochondrial intermembrane space (IMS), whereby it protects the liver against various types of injury. In this review, we describe the role of ALR in regulating hepatocytes in the context of NAFLD. We also discuss questions about ALR that remain to be explored in the future. In conclusion, ALR appears to be a promising therapeutic target for treating NAFLD.

Single-cell transcriptomes identifies characteristic features of mouse macrophages in liver Mallory-Denk bodies formation

Mallory-Denk bodies (MDBs) consist of intracellular aggregates of misfolded proteins in ballooned hepatocytes and serve as important markers of progression in certain liver diseases. Resident hepatic macrophage-mediated inflammation influences the development of chronic liver diseases and cancer. Here, the first systematic study of macrophages heterogeneity in mice was conducted to illustrate the pathogenesis of MDB formation using single-nucleus RNA sequencing (snRNA-seq). Furthermore, we provided transcriptional profiles of macrophages obtained from the fractionation of mouse liver tissues following chronic injury. We equally identified seven discrete macrophage subpopulations, each involved in specific cellular activated pathways such as basal metabolism, immune regulation, angiogenesis, and cell cycle regulation. Among these, a specific macrophage cluster (Cluster4), a subpopulation specifically expressing genes that regulate cell division and the cell cycle, was identified. Interestingly, we found that CCR2 was significantly induced in Cluster2, thereby inducing monocytes to migrate to macrophages to promote MDB pathogenesis. Thus, our study is the first to demonstrate the heterogeneity of macrophages associated with liver MDB formation in mice through single-cell resolution. This serves as the basis for further insights into the pathogenesis of liver MDB formation and molecular mechanisms of chronic liver disease progression.

Transcriptomic profiles of human livers undergoing rewarming machine perfusion before transplantation-first insights

Machine perfusion by controlled oxygenated rewarming (COR) is feasible and safe in clinical application and result in a promising outcome. This study utilizes next-generation sequencing (NGS) to investigate the transcriptome of human liver tissue undergoing COR before liver transplantation. Cold-stored livers were subjected to machine-assisted slow COR for ~120 min before transplantation. Biopsies were taken before (preCOR) and after COR (postCOR) and 1 h after reperfusion (postRep). The samples were sequenced, using RNA-seq to analyze differential transcriptional changes between the different stages and treatments of the grafts. Comparison of differential gene expression preCOR and postCOR demonstrated 10 upregulated genes. postRep 97 and 178 genes were upregulated and 7 and 13 downregulated compared to preCOR and postCOR, respectively. A shift of gene expressions by machine perfusion to the TGF-beta pathway was observed. The present study demonstrates distinct transcriptome profiles associated with machine perfusion by COR and transplantation of human livers. Such data provide a deeper understanding of the molecular mechanisms of machine perfusion technology in human liver transplantation.

Co-cultured bone marrow mesenchymal stem cells repair thioacetamide-induced hepatocyte damage

Adult stem cells, such as bone marrow mesenchymal stem cells (BMSCs), are postdevelopmental cells found in many bone tissues. They are capable of multipotent differentiation and have low immune-rejection characteristics. Hepatocytes may become inflamed and produce a large number of free radicals when affected by drugs, poisoning, or a viral infection. The excessive accumulation of free radicals in the extracellular matrix (ECM) eventually leads to liver fibrosis. This study aims to investigate the restorative effects of mouse bone marrow mesenchymal stem cells (mBMSCs) on thioacetamide (TAA)-induced damage in hepatocytes. An in vitro transwell co-culture system of HepG2 cells were co-cultured with mBMSCs. The effects of damage done to TAA-treated HepG2 cells were reflected in the overall cell survival, the expression of antioxidants (SOD1, GPX1, and CAT), the ECM (COL1A1 and MMP9), antiapoptosis characteristics (BCL2), and inflammation (TNF) genes. The majority of the damage done to HepG2 by TAA was significantly reduced when cells were co-cultured with mBMSCs. The signal transducer and activator of transcription 3 (STAT3) and its phosphorylated STAT3 (p-STAT3), as related to cell growth and survival, were detected in this study. The results show that STAT3 was significantly decreased in the TAA-treated HepG2 cells, but the STAT3 and p-STAT3 of HepG2 cells were significantly activated when the TAA-treated HepG2 co-cultured with mBMSCs. Strong expression of interleukin (Il6) messenger RNA in co-cultured mBMSCs/HepG2 indicated mBMSCs secret the cytokines IL-6, which promotes cell survival through downstream STAT3 activation and aid in the recovery of HepG2 cells damaged by TAA.

The Macrophage Activation Marker Soluble CD163 is Associated With Early Allograft Dysfunction After Liver Transplantation

BACKGROUND/OBJECTIVES

Soluble CD163 (sCD163), a macrophage activation marker, is upregulated in conditions of macrophage proliferation and activation. Elevated sCD163 levels have been associated with liver disease severity and progression. During liver transplantation, the implanted liver is exposed to ischaemia and reperfusion injury, resulting in an acute inflammatory response and macrophage activation. The relationship between sCD163 levels during liver transplantation and the development of early allograft dysfunction (EAD) has not been investigated.

METHODS

We included 27 cirrhosis patients (age 55 [range 32-72] years, 23 men) on the waiting list for liver transplantation. Alcohol consumption and viral hepatitis were the most frequent causes for cirrhosis. Patients were characterised by standard biochemical analysis and based on clinical disease severity scores. Information about donor, graft and course of the liver transplantation was recorded. sCD163 levels were measured at the time of liver transplantation before surgery, 2 h after reperfusion, and then at 24 h after transplantation.

RESULTS

We observed above-normal sCD163 levels at baseline (5.9 mg/L [4.7-8.8]). Two hours after reperfusion, sCD163 levels increased significantly from baseline (8.4 mg/L [7.4-10.9]; P < 0.01). Twenty-four hours after transplantation, sCD163 levels were significantly reduced compared with baseline (3.7 mg/L [2.9-5.5]; P < 0.01). However, in patients with EAD (n = 16), sCD163 levels were increased compared with patients without EAD (4.1 [3.2-7.4] vs. 3.1 [2.8-3.8] mg/L; P = 0.03).

CONCLUSIONS

We observed elevated sCD163 levels in patients with EAD after liver transplantation, confirming macrophage activation to play a role in EAD. Thus, sCD163 may be used as an early marker for EAD after liver transplantation, but larger studies are warranted to validate these findings.

Comparison of Liver Graft Regeneration Between ABO-Compatible and ABO-Incompatible Living Donor Liver Transplantation: A Propensity Score Matching Analysis

BACKGROUND ABO-incompatible (ABOi) living donor liver transplantation (LDLT) was accepted as a feasible therapy for end-stage liver disease after the introduction of rituximab. The present study investigated the association between ABO incompatibility and graft regeneration in patients who underwent LDLT. MATERIAL AND METHODS A total of 335 adult patients who underwent elective LDLT were divided into ABO-compatible (ABOc) and ABOi LDLT groups using propensity score (PS) matching of graft regeneration-related factors. Postoperative serial changes in graft volumes were compared between the groups. The factors associated with graft volume on postoperative day (POD) 21 were investigated in patients who underwent ABOi LDLT. RESULTS In total, 300 (89.6%) patients underwent ABOc LDLT and 35 (10.4%) patients underwent ABOi LDLT. After PS matching, the ABOc and ABOi groups each included 32 paired patients. The absolute liver graft volumes on POD 21 were significantly lower in the ABOi group than those in the ABOc group in the PS-matched patients (1098.4 [964.0-1,162.0] vs. 1202.0 [1107.8-1455.2] mL; p=0.007). Major complications, including overall patient mortality during the follow-up period, did not differ between the groups. In patients who underwent ABOi LDLT, the preoperative graft volume/standard liver volume ratio and CD4+ cell level on POD 14 were independent factors related to liver graft volume on POD 21. CONCLUSIONS These results suggest that ABO incompatibility could affect postoperative liver graft regeneration. Therefore, graft regeneration must be investigated using a volumetric assessment in patients who have undergone ABOi LDLT.

A novel dual ex vivo lung perfusion technique improves immediate outcomes in an experimental model of lung transplantation

The lungs are dually perfused by the pulmonary artery and the bronchial arteries. This study aimed to test the feasibility of dual-perfusion techniques with the bronchial artery circulation and pulmonary artery circulation synchronously perfused using ex vivo lung perfusion (EVLP) and evaluate the effects of dual-perfusion on posttransplant lung graft function. Using rat heart-lung blocks, we developed a dual-perfusion EVLP circuit (dual-EVLP), and compared cellular metabolism, expression of inflammatory mediators, and posttransplant graft function in lung allografts maintained with dual-EVLP, standard-EVLP, or cold static preservation. The microvasculature in lung grafts after transplant was objectively evaluated using microcomputed tomography angiography. Lung grafts subjected to dual-EVLP exhibited significantly better lung graft function with reduced proinflammatory profiles and more mitochondrial biogenesis, leading to better posttransplant function and compliance, as compared with standard-EVLP or static cold preservation. Interestingly, lung grafts maintained on dual-EVLP exhibited remarkably increased microvasculature and perfusion as compared with lungs maintained on standard-EVLP. Our results suggest that lung grafts can be perfused and preserved using dual-perfusion EVLP techniques that contribute to better graft function by reducing proinflammatory profiles and activating mitochondrial respiration. Dual-EVLP also yields better posttransplant graft function through increased microvasculature and better perfusion of the lung grafts after transplantation.

Genomics of liver transplant injury and regeneration

While improved surgical techniques, post-operative care, and immunosuppression regimens have reduced morbidity and mortality associated with orthotopic liver transplantation (OLT), further improvement of outcomes requires personalized treatment and a better understanding of genomic mechanisms involved. Gene expression profiles of ischemia/reperfusion (I/R) injury, regeneration, and rejection, may suggest mechanisms for development of better predictive tools and treatments. The liver is unique in its regenerative potential, recovering lost mass and function after injury from ischemia, resection, and rejection. I/R injury, an inevitable consequence of perfusion cessation, cold storage, and reperfusion, is regulated by the interaction of the immune system, inflammatory cytokines, and reduced microcirculatory blood flow in the liver. Rejection, a common post-operative complication, is mediated by the recipient's immune system through T-cell-dependent responses activating proinflammatory and apoptotic pathways. Characterizing distinctive gene expression signatures for these events can identify therapies to reduce injury, promote regeneration, and improve outcomes. While certain markers of liver injury and regeneration have been observed in animals, many of these are unverified in human studies. Further investigation of these genomic signatures and mechanisms through new technology offers promise, but continues to pose a significant challenge. An overview of the current fund of knowledge in this area is reviewed.

Liver regeneration after liver transplantation

BACKGROUND/PURPOSE

The liver has a remarkable capacity to regenerate after injury or resection. The aim of this review is to outline the mechanisms and factors affecting liver regeneration after liver transplantation.

METHODS

Relevant studies were reviewed using Medline, PubMed and Springer databases.

RESULTS

A variety of cytokines (such as interleukin-6 and tumor necrosis factor-α), growth factors (like hepatocyte growth factor and transforming growth factor-α) and cells are involved in liver regeneration. Several factors affect liver regeneration after transplantation such as ischemic injury, graft size, immunosuppression, steatosis, donor age and viral hepatitis.

CONCLUSION

Liver regeneration has been studied for many years. However, further research is essential to reveal the complex processes affecting liver regeneration, which may provide novel strategies in the management of liver transplantation recipients and donors.

Evaluating human liver reserve function by measuring serum concentrations of phenacetin and its metabolites

OBJECTIVES

To evaluate human liver reserve function (LRF) by a simple and efficient method for measuring serum concentrations of phenacetin and its metabolites.

METHODS

Overall 20 patients with liver cirrhosis (Child-Pugh score ≥ 7, aged 48-79 years), 30 healthy young volunteers (aged 18-40 years), and 20 healthy elderly volunteers (aged 61-80 years) were enrolled. All participants received a single oral dose of 0.5 g phenacetin. Liquid chromatography tandem mass spectrometry was used to determine the serum concentrations of phenacetin and its metabolites, including acetaminophen, acetaminophen glucuronide and acetaminophen sulfate.

RESULTS

The serum concentration of phenacetin was significantly higher in cirrhotic patients than those in either of the healthy volunteer groups (P < 0.001). It was higher in healthy elderly volunteers than that in healthy young ones but there was no statistically significant difference (P > 0.05) between them. The serum concentrations of acetaminophen, acetaminophen glucuronide and acetaminophen sulfate were significantly lower in cirrhotic patients than in the healthy controls (P < 0.001). The serum concentrations of these three metabolites in healthy elderly volunteers were lower than those in healthy younger volunteers but again, there was no statistical significant difference (P > 0.05). The serum concentration of acetaminophen in healthy male volunteers was significantly higher than that in the women (P < 0.05).

CONCLUSION

Monitoring cytochrome P450 1A2 (CYP450 1A2)-mediated phenacetin metabolism is a simple and efficient method for evaluating human LRF. This method would warrant further validation in a large cohort clinical study.

Current status of oxidative stress in pediatric liver transplantation

Generation of free radicals in children after liver transplantation is multifactorial from ischemia-reperfusion injury, immunosuppression and post-transplant complications. Thus, this group is at higher risk of oxidative imbalance with molecular and clinical consequences. We discuss pathogenesis and ways of action against oxidative stress in liver transplant recipients.

Variations in Interferon Gamma Receptor Gene Expression during Liver Regeneration after Partial Hepatectomy in Rats

Cell-mediated immunity, which includes interferon gamma (IFN-γ) expression, is activated during the process of liver regeneration; however, the genetic pathway of this activation is still unclear. The present study evaluated variations in the interferon gamma receptor (IFN-γR) gene and its mRNA expression during liver regeneration after partial hepatectomy (PH). Male Wistar rats weighing approximately 200 g were subjected to PH (70 or 40%). IFN-γR gene expression in the remnant liver was measured by cDNA microarray, and mRNA expression was verified by real-time quantitative reverse transcription-polymerase chain reaction (Q-PCR) preoperatively and at 2, 4, 6,12, 24, and 72 hours and 7 days postoperatively. The ratio of remnant liver weight to body weight increased markedly after 70 per cent PH and more gradually after 40 per cent PH. It reached near 90 per cent of the preoperative level at 72 hours after PH in both groups. The scanned spots of the genomic survey on the cDNA microarray chips were uneven and increased irregularly in number and density after PH. IFN-γR gene expression increased markedly in a single peak pattern, up to more than double the preoperative level, at 6 hours after 70 per cent PH. The curve in the 40 per cent PH group was flat and peaked at only 1.6 times the preoperative level. The variations in IFN-γR-related mRNA expression were verified by Q-PCR. Elevations in IFN-γR gene and mRNA expression were shown during the early stage of liver regeneration after PH. The genetic pathway of IFN-γ/IFN-γR expression is activated during liver regeneration.

Effect of ischemia-reperfusion on the incidence of acute cellular rejection and timing of histologic hepatitis C virus recurrence after liver transplantation

BACKGROUND

Because of a critical shortage of deceased donor (DD) livers, more extended criteria allografts are being utilized; these allografts are at increased risk for ischemia-reperfusion injury (IRI). We assessed whether, in a large cohort of patients transplanted for hepatitis C virus (HCV) either via a DD or live donor (LD), there was a relationship between the degree of IRI and the frequency and timing of acute cellular rejection (ACR) and histologic HCV recurrence.

METHODS

During an 8-year study, patients were separated into four groups based on peak alanine aminotransferase (ALT) levels and three groups based on severity of IRI on postreperfusion liver biopsy.

RESULTS

The mean follow-up time of 433 DD and 44 LD recipients was 1212 days. We noted a strong correlation in DD between peak ALT and the histologic degree of IRI (P = .01). There was no difference in the incidence or grade of ACR among the four groups. There was no correlation between the severity of IRI and the incidence or time to histologic recurrence of HCV.

CONCLUSIONS

The magnitude of peak ALT correlated with the severity of IRI on postreperfusion liver biopsy. Among this large HCV cohort, there was no correlation between the severity of IRI and the incidence or timing of histologic HCV recurrence or incidence of ACR.

Role of Kupffer cells in the induction of tolerance of orthotopic liver transplantation in rats

Because the role of Kupffer cells (KCs) in liver transplantation (LT) tolerance is not well understood, we investigated their role in liver allograft acceptance in rats. Male Sprague-Dawley rats were randomly assigned to either an LT group or a transplantation group pretreated with GdCl(3) (Gd group). The rats were postoperatively sacrificed at indicated times for histology and assessment of KC function, nuclear factor kappa B (NF-kappaB) activity, and cytokine production. KCs and T cells (TCs) were isolated from allografts to assess Fas/Fas ligand (FasL) expression. Cytotoxicity of KCs against TCs was monitored by coculturing of (3)H-thymidine TCs with KCs at various effector-to-target ratios. The results were as follows. First, grafts were spontaneously accepted in the LT group with evident apoptosis of TCs; however, inhibition of KCs by pretreatment with GdCl(3) decreased TC apoptosis and shortened the survival of allografts. Second, KCs in the LT group had increased levels of FasL messenger RNA and protein with respect to that in the Gd group. Third, by in vitro cocultivation assays, KCs induced TC apoptosis though elevated expression of FasL, and this process could be blocked by anti-FasL antibody. Fourth, there was a positive correlation between activation of NF-kappaB and FasL expression in KCs and interleukin-4 production in the LT group, and the activation of NF-kappaB was inhibited by pretreatment with GdCl(3). In conclusion, KC-induced depletion of TCs via the Fas/FasL pathway might play a critical role in LT tolerance. However, the tolerance is abrogated by suppression of FasL and IL-4 expression via inhibition of NF-kappaB activity by GdCl(3).

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.

METHODS

Using an orthotopic liver transplantation model, the effects on rat liver preservation of a modified preservation solution (UW-PEG) were evaluated, based on the inversion of K(+) and Na(+) concentration and the replacement of HES by PEG 35 kDa (0.03 mmol/L) in UW preservation solution.

RESULTS

The use of UW-PEG preservation solution ameliorated the biochemical and histological parameters of hepatic damage. Thus, at 24 h after transplantation, transaminase levels were reduced significantly when livers were preserved during 8 h in UW-PEG preservation solution compared with the original UW solution. In addition, histological findings revealed fewer and smaller areas of hepatocyte necrosis. The benefits of UW-PEG solution cannot be explained by modifications in oxidative stress or neutrophil accumulation associated with liver transplantation. However, the results of hepatic and portal blood flow indicated that the benefits of this modified preservation solution, UW-PEG were associated with improvements in the microcirculatory disorders after reperfusion.

CONCLUSIONS

The UW-PEG solution, while retaining all the advantages of UW solution, improved hepatic ischemia-reperfusion injury associated with liver transplantation.

Rating of CCl(4)-induced rat liver fibrosis by blood serum glycomics

BACKGROUND

Non-invasive staging of human liver fibrosis is a desirable objective that remains under extensive evaluation. Animal model systems are often used for studying human liver disease and screening antifibrotic compounds. The aim of the present study was to investigate the potential use of serum N-glycan profiles to evaluate liver fibrosis in a rat model.

METHODS

Liver fibrosis and cirrhosis were induced in rats by oral administration of CCl(4). Liver injury was assessed biochemically (alanine aminotransferase [ALT] activity, aspartate aminotransferase [AST] activity and total bilirubin) and histologically. The N-glycan profile (GlycoTest) was performed using DNA sequencer-assisted-fluorophore-assisted carbohydrate electrophoresis technology. In parallel, the effect of cotreatment with antifibrotic interferon-gamma (IFN-gamma) was studied.

RESULTS

The biopsy scoring system showed that CCl(4) induced early fibrosis (F < 1-2) in rats after 3 weeks of treatment, and cirrhosis (F4) after 12 weeks. Significant increases in ALT activity, AST activity and total bilirubin levels were detected only after 12 weeks of CCl(4) treatment. GlycoTest showed three glycans were significantly altered in the CCl(4)-goup. Peak 3 started at week 6, at an early stage in fibrosis development (F < 1-2), whereas peaks 4 and 5 occurred at week 9, at which time mild liver fibrosis (F = 1-2) had developed. The changes in the CCl(4)-IFN-gamma group were intermediate between the CCl(4)- and the control groups.

CONCLUSION

The GlycoTest is much more sensitive than biochemical tests for evaluating liver fibrosis/cirrhosis in the rat model. The test can also be used as a non-invasive marker for screening and monitoring the antifibrotic activity of potential therapeutic compounds.

Organ transplantation in rodents: novel applications of long-established methods

Rodent models of solid organ transplantation have been used for many decades. Standardized operative techniques resulting in highly reproducible survival rates have been developed for several organs. This allowed scientists to investigate many clinically relevant problems, test new drugs and establish novel treatment regimens. Recently, many studies used these models to explore novel issues such as graft modification by pharmaceutical, surgical or genetic engineering methods, post-transplant regeneration, leukocyte trafficking or interactions between the innate and allo-specific arms of the immune response. The results from these studies clearly facilitate a more complex and comprehensive understanding of existing problem. The long-established methods of rodent organ transplantation, combined with the newest achievements in surgical techniques, biotechnology and imaging, will remain indispensable tools of transplantation biology.

Liver I/R injury is improved by the arginase inhibitor, N(omega)-hydroxy-nor-L-arginine (nor-NOHA)

Liver ischemia-reperfusion (I/R) injury is associated with profound arginine depletion due to arginase release from injured hepatocytes. The purpose of this study was to determine whether arginase inhibition with N(omega)-hydroxy-nor-l-arginine (nor-NOHA) would increase circulating arginine levels and decrease hepatic damage during liver I/R injury. The effects of nor-NOHA were initially tested in normal animals to determine in vivo toxicity. In the second series of experiments, orthotopic syngeneic liver transplantation (OLT) was performed after 18 h of cold ischemia time in Lewis rats. Animals were given nor-NOHA (100 mg/kg) or saline before and after graft reperfusion. In normal animals treated with nor-NOHA, there were no histopathological changes to organs, liver enzymes, serum creatinine, or body weight. In the OLT model, animals treated with saline exhibited markedly elevated serum transaminases and circulating arginase protein levels. Nor-NOHA administration blunted the increase in serum arginase activity by 80% and preserved serum arginine levels at 3 h after OLT. Nor-NOHA treatment reduced post-OLT serum liver enzyme release by 50%. Liver histology (degree of necrosis) in nor-NOHA-treated animals was markedly improved compared with the saline-treated group. Furthermore, use of the arginase inhibitor nor-NOHA did not influence polyamine synthesis owing to the decrease in ornithine levels. Arginase blockade represents a potentially novel strategy to combat hepatic I/R injury associated with liver transplantation.

Gene Expression Profiles in Living Donors Immediately After Partial Hepatectomy—The Initial Response of Liver Regeneration

BACKGROUND/PURPOSE

Gene expression profiles of liver regeneration are well explored in rat models. However, there are limited relative data in humans. This study aimed to show that mRNA expression profiles change immediately after right hepatectomy in living-related donors and correlate with mechanisms of liver regeneration reported in the literature.

METHODS

Prospective study was conducted from March 2003 to August 2004. Living-related donors who donated right lobe of liver were included. Liver biopsies were performed at the beginning and, 5 hours later, at the end of liver resection. RNAs were isolated to synthesize cRNA. Oligo DNA microarray experiments were conducted and paired signal intensity ratios (Cy3/Cy5) were normalized with rank-invariant global Lowess regression analysis by taking base two logarithms. Genes whose average residuals more than 2.5-fold increased or less than -2.5-fold decreased were selected to get the most pronounced expression changes during this period.

RESULTS

Five of 34 donors were included with qualified samples. The expression patterns of paired DNA microarray experiments were similar in five donors. A total of 28 upregulated and 14 downregulated genes were collected. Acute-phase proteins (serum amyloid A, complement-reactive protein, heme oxygenase-1) were upregulated. Genes related to growth signal transduction (G-protein coupled receptor-30) were downregulated.

CONCLUSION

Gene expression profiles immediately after partial hepatectomy were reported first in humans with the techniques of oligo DNA microarray, which were compatible with the initial gene expression patterns of liver regeneration in rats.

Interleukin-6 and STAT3 protect the liver from hepatic ischemia and reperfusion injury during ischemic preconditioning

BACKGROUND

Ischemic preconditioning has been shown to protect the liver from ischemia/reperfusion injury. We hypothesized that IL-6 directly modulates the protective effects of ischemic preconditioning.

METHODS

Three weeks after undergoing splenic transposition, wild-type C57BL/6 and IL-6 null mice underwent 75 minutes of total hepatic ischemia with or without prior ischemic preconditioning (10 minutes of ischemia followed by 15 minutes of reperfusion). After reperfusion, serum ALT, serum IL-6, hepatic IL-6 mRNA, hepatic pSTAT3, and liver histology were evaluated.

RESULTS

In wild-type mice, survival at 24 hours was greater in the preconditioned group compared with the non-preconditioned group (75% vs 40%, P<.05). In IL-6 null mice, however, ischemic preconditioning did not improve survival when compared with the non-preconditioned group. Preconditioning significantly reduced hepatocellular injury in wild-type mice (P<.05) when compared with IL-6 null animals. This protection was associated with significant increases in serum IL-6, hepatic IL-6 mRNA, and hepatic pSTAT3 levels (P<.05). The protective effects of ischemic preconditioning that correlated with significant increases in systemic IL-6, hepatic IL-6 mRNA abundance, and pSTAT3 levels, were not observed in IL-6 null mice.

CONCLUSIONS

The protective effects of ischemic preconditioning during total hepatic ischemia/reperfusion injury are dependent on IL-6 signaling and are associated with increased phosphorylation of hepatic STAT3.

Molecular adsorbent recirculating system in patients with early allograft dysfunction after liver transplantation: a pilot study

Early allograft dysfunction (EAD) after orthotopic liver transplantation (OLT) causes marked morbidity and mortality. We conducted a prospective pilot study to assess the safety and efficacy of molecular adsorbent recirculating system (MARS) in treatment of EAD after OLT. Twelve consecutive adult liver allograft recipients with a median age of 48 years, 9 of whom were male, were prospectively included and supported with MARS. EAD was defined as the presence of at least 2 of the following: serum bilirubin >10 mg/dL, prothrombin time <40%, aspartate aminotransferase or alanine transferase >1,000 U/L, and plasma disappearance rate of indocyanine green (PDR(ICG)) <10% per minute within 72 hours after reperfusion. One-year patient and graft survival was 66%. There was a significant decrease in serum bilirubin (P = 0.002), serum creatinine (P = 0.006), and aspartate aminotransferase (P = 0.005) and a significant increase in PDR(ICG) (P = 0.007) after MARS treatment. Prothrombin time, albumin level, and platelet count remained stable. Sustained improvement of renal and neurological function and of mean arterial pressure were observed. No MARS-related adverse effects occurred. MARS treatment provides a safe approach to the treatment of EAD after OLT. On the basis of this pilot study, a multicenter randomized clinical trial that uses MARS treatment in EAD after OLT has been initiated.

Augmenter of liver regeneration promotes hepatocyte proliferation induced by Kupffer cells

AIM

To observe the effects of augmenter of liver regeneration (ALR) on Kupffer cells and to determine whether ALR promotes hepatocyte proliferation induced by Kupffer cells.

METHODS

Kupffer cells and hepatocytes were cultured in vitro and various concentrations of recombinant rat ALR (rrALR) were added. 3H-thymidine, BrdU and 3H-leucine incorporation was determined in cultured Kupffer cells and hepatocytes, in hepatocytes conditioned by Kupffer cells, and in associated medium. rrALR was labeled by iodination and used to determine its binding activity by Scatchard analysis in Kupffer cells and primarily cultured rat hepatocytes.

RESULTS

rrALR stimulated DNA replication in Kupffer cells and protein synthesis both in cells and in medium in a non-concentration-dependent manner. The effect was significant at the concentration of 1 microg/L ALR. However, rrALR had no effect on primarily cultured hepatocytes, when hepatocytes were cultured with the Kupffer cell medium conditioned by ALR, DNA replication and protein synthesis in hepatocytes increased significantly at the concentration of 1 microg/L ALR. When the ALR concentration was increased, its effect on hepatocyte proliferation decreased to the basal level. Scatchard analysis indicated the presence of a single class of high affinity receptors with a dissociation constant (Kd) of 0.883 nmol/L and a maximum binding capacity (Bmax) of 126.1 pmol/g protein in the rat Kupffer cells.

CONCLUSION

ALR can promote hepatocyte proliferation induced by Kupffer cells, which is associated with the concentration of ALR, suggesting that Kupffer cells play a dual role in liver regeneration.

The transcription factor interferon regulatory factor-1 mediates liver damage during ischemia-reperfusion injury

Hepatic ischemia occurs in the settings of trauma, transplantation, and elective liver resections. The initiating events that account for local organ damage are only partially understood. Interferon (IFN) regulatory factor-1 (IRF-1) is a transcription factor that regulates the expression of a number of genes involved in both innate and acquired immunity; however, its function in liver injury is unknown. Therefore, the purpose of this study was to investigate the role of IRF-1 in hepatic ischemia-reperfusion (I/R) injury. In C57BL/6 mice undergoing 60 min of hepatic ischemia, IRF-1 protein expression increased as early as 1 h after reperfusion. IRF-1 knockout mice were significantly protected from hepatic I/R-induced damage compared with their wild-type controls. Hepatic I/R injury resulted in marked activation of the MAP kinase c-Jun NH(2)-terminal kinase (JNK) in wild-type mice but not IRF-1 knockout mice. IRF-1 knockout mice also exhibited significantly lower hepatic expression of TNF-alpha, IL-6, ICAM-1, and inducible nitric oxide synthase (iNOS) mRNA. Adenoviral delivery of IRF-1 into C57BL/6 mice resulted in increased liver damage even without an ischemic insult. This injury was associated with increased JNK activation and hepatic iNOS expression. Because IRF-1 contributed to liver injury, we also examined for inflammatory signals that regulated IRF-1 gene expression in cultured hepatocytes. Whereas IFN-gamma and IFN-beta were strong inducers of IRF-1 mRNA (>10-fold) in a time- and dose-dependent manner, TNF-alpha and IL-1beta also induced IRF-1 mRNA to a lesser extent (2- to 3-fold). IL-6 and lipopolysaccharide had no effect on IRF-1 expression. This study demonstrates that IRF-1 exerts a harmful role in hepatic I/R injury by modulating the expression of multiple inflammatory mediators. We further show that IRF-1-mediated injury involves the activation of JNK and that hepatocellular IRF-1 expression itself is regulated by specific cytokines.

Liver Regeneration and Splenic Enlargement in Donors after Living-Donor Liver Transplantation

Liver regeneration after donor hepactectomy offers a unique insight into the process of liver regeneration in normal livers. As the liver restores itself, concurrent splenic enlargement occurs. There are many theories about why this phenomenon takes place: some investigators have proposed a relative portal hypertension that leads to splenic congestion or, perhaps, the presence of a common growth factor that induces both the liver and spleen to enlarge. Between the months of June 2001 and May 2004, 112 live donor liver transplants (LDLTs) were performed in Chang Gung Memorial Hospital, Kaohsiung, Taiwan. The total number of donor hepatectomies performed during this period was 113, however, because one of the cases required dual donors. Of our 113 donors, we eventually analyzed the data of 109; 4 patients were lost to follow-up 6 months later and were excluded from our study. The average age of our donor population was 32.32 +/- 8.48 years. The mean liver volume at donation was noted to be 1207.72 +/- 219.95 cm3, and 6 months later, it was 1027.18 +/- 202.41 cm3. Expressed as a percentage of the original volume, the mean liver volume 6 months after hepatectomy was 90.70% +/- 12.47% in this series. For right graft donors, mean liver volume after 6 months was 89.68% +/- 12.37% of the original liver volume, whereas that for left graft donors was 91.99% +/- 12.6%. Only 26 of the 109 (23.85%) donors were able to achieve full regeneration 6 months post-donation. Notably, liver function profiles of all donors were normal when measured 6 months after operation. The average splenic volume at donation as measured by computed tomography (CT) volumetry was 159 +/- 58 cm3, and the splenic volume 6 months post-donation was 213 +/- 85 cm3. There was a mean increment in splenic volume of 35% +/- 28% 6 months after donation. The blood profiles of the donors were monitored; particular attention was given to platelet levels and liver function tests, and these were found to be within normal limits 6 months after operation. Of note, splenic enlargement was significantly greater among right-sided donors than their left-sided counterparts. Greater splenic enlargement was also observed in those donors who achieved full liver regeneration at their evaluation 6 months postoperatively than in those who did not. Although original liver volume was not re-established in most patients 6 months after liver donation, there seemed to have been no untoward effects to the donor. The factors that affect liver regeneration are complex and myriad. Although there is splenic enlargement at 6 months post-donation in donors of LDLT, there are no untoward effects of this enlargement.

Early perioperative death associated with reexpansion pulmonary edema during liver transplantation

Hydrothorax is a frequent finding in patients with end-stage liver disease. During the hepatectomy phase of liver transplantation, it is often needed to evacuate large pleural effusions. The acute expansion of the collapsed lung can cause reexpansion pulmonary edema with variable clinical significance. However, this complication has rarely been reported after liver transplantation. In conclusion, we report on an overwhelming reexpansion pulmonary edema during a liver transplantation that rapidly led to the patient's demise and speculate if this condition has not been under recognized in the transplantation setting.

The contemporary role of antioxidant therapy in attenuating liver ischemia-reperfusion injury: a review

Oxidative stress is an important factor in many pathological conditions such as inflammation, cancer, ageing and organ response to ischemia-reperfusion. Humans have developed a complex antioxidant system to eliminate or attenuate oxidative stress. Liver ischemia-reperfusion injury occurs in a number of clinical settings, including liver surgery, transplantation, and hemorrhagic shock with subsequent fluid resuscitation, leading to significant morbidity and mortality. It is characterized by significant oxidative stress but accompanied with depletion of endogenous antioxidants. This review has 2 aims: firstly, to highlight the clinical significance of liver ischemia-reperfusion injury, the underlying mechanisms and the main pathways by which the antioxidants function, and secondly, to describe the new developments that are ongoing in antioxidant therapy and to present the experimental and clinical evidence about the role of antioxidants in modulating hepatic ischemia-reperfusion injury.

Gadolinium chloride-induced improvement of postischemic hepatic perfusion after warm ischemia is associated with reduced hepatic endothelin secretion

Selective Kupffer cell blockade by gadolinium chloride (GdCl(3)) pretreatment of liver donors previously proved to be effective in reducing ischemia/reperfusion injury in rat liver transplants. Physiological mechanisms of this effect have not been specified so far. Vasoactive peptides are involved in liver blood flow regulation. We tested the hypothesis, that hepatic hemodynamic effects of GdCl(3) pretreatment are mediated by intrahepatic endothelin-1 (ET) secretion in a standardized porcine model of warm liver ischemia and reperfusion. Standardized warm hepatic ischemia (45 min) was induced after laparotomy in intubation narcoses (ITN) by Pringle-maneuver in pigs (n = 12). Animals were either pretreated with GdCl(3) (20 mg/kg i.v.) or sodium chloride 0.9% (control group) in a randomized manner 24 h before investigation. Relaparotomy was performed at day 7. Before, during ischemia and until 6 h after liver reperfusion, transhepatic blood flow (portal venous + hepatic artery flow) was defined by ultrasonic flow probes and hepatic parenchymous microcirculation evaluated by implanted thermodiffusion electrodes. ET plasma concentrations were analyzed (commercial RIA) at all time points in the hepatic veins after selective canulation. GdCl(3) pretreatment of animals markedly improved hepatic macro- and microperfusion before and particularly after warm ischemia. Mean ET plasma concentrations in the hepatic vein were significantly lower before, 6 h and 7 days after ischemia, compared with controls. Kupffer cell destruction by GdCl(3) pretreatment improves hepatic micro- and macroperfusion after warm ischemia, thus indicating reduced ischemia/reperfusion injury. Documented reduction of postischemic liver blood flow impairment after GdCl(3) pretreatment could be mediated by a decreased hepatic ET secretion, as hemodynamic effects were associated with significantly reduced ET plasma levels in hepatic veins.

Effects of duration of ischemia and donor pretreatment with methylprednisolone or its macromolecular prodrug on the disposition of indocyanine green in cold-preserved rat livers

PURPOSE

Cold preservation of the liver before transplantation may change uptake and excretory functions of hepatocytes. We hypothesized that an increase in the duration of preservation would result in a progressive decrease in the hepatic uptake and/or biliary excretion of indocyanine green (ICG), which would be attenuated by pharmacologic interventions.

METHODS

Donor rats (n = 40) were administered saline (control) or single 5 mg/kg doses of methylprednisolone (MP) or its liver-targeted prodrug (DMP) 2 h prior to liver harvest. Following preservation in cold University of Wisconsin solution for 0, 24, 48, or 72 h, livers were reperfused in a single-pass manner for 30 min in the presence of ICG (approximately 4 microg/ml), followed by 60 min of ICG-free perfusion. The inlet, outlet, and bile concentrations of ICG were measured periodically by high performance liquid chromatography (HPLC), and kinetic parameters were estimated.

RESULTS

Effects of duration of preservation: In unpreserved livers, a significant portion of ICG dose (16%) was effluxed from the liver during the washout period. Cold preservation for 24-72 h progressively increased (p < 0.05) the efflux of ICG (>2-fold at 72 h). Similarly, average extraction ratio showed a modest (30-40%) decrease with increasing preservation time (p < 0.05). However, biliary excretion of ICG showed the most sensitivity to the preservation time (14 to >800-fold decline). Effects of pretreatment: DMP caused significant (p < 0.05) increases in biliary ICG levels (>12-fold) and bile flow rates (6-15-fold) of preserved livers. Although MP pretreatment significantly (p < 0.05) increased (6-fold) bile flow rates in 48-h preserved livers, its effects on biliary ICG levels were not significant (p > 0.05).

CONCLUSIONS

Biliary excretion of ICG is the most sensitive kinetic parameter to prolonged cold ischemia-reperfusion injury in a rat liver perfusion model. The injury may be significantly attenuated by pharmacologic pretreatment of the liver donors.

Ethyl pyruvate ameliorates liver ischemia-reperfusion injury by decreasing hepatic necrosis and apoptosis

BACKGROUND

Hepatic ischemia-reperfusion injury (I/R) occurs in the settings of transplantation, trauma, and elective liver resections. Reactive oxygen species (ROS) have been shown to play a major role in organ I/R injury. Pyruvate, a key intermediate in cellular metabolism, is an effective scavenger of ROS. The purpose of this study was to test the hypothesis that ethyl pyruvate (EP), a soluble pyruvate derivative, is effective in preventing hepatic I/R injury.

METHODS

Lewis rats underwent 60 minutes of partial warm hepatic ischemia. Three doses of EP dissolved in lactated Ringer's solution or lactated Ringer's solution (LR) alone were given by intravenous injection. Serum and tissue samples were obtained at 1 to 24 hours postreperfusion.

RESULTS

Serum transaminases, degree of hepatic necrosis, and neutrophil infiltration were all significantly decreased in the EP-treated rats compared with control animals. The amount of hepatic lipid peroxidation was also significantly decreased in EP-treated animals. Both circulating levels and hepatic expression of inflammatory cytokines were significantly decreased in the EP-treated animals. Furthermore, EP inhibited activation of extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase mitogen-activated protein kinases, as well as nuclear factor-kappaB, signaling pathways involved in cytokine release. Treatment with EP also inhibited hepatic apoptosis.

CONCLUSION

EP has a protective effect on hepatic I/R injury, mediated in part by decreasing lipid peroxidation, down-regulation of inflammatory mediators, and inhibition of apoptosis. Strategies using this additive to LR solution should be considered in clinical settings of ischemic liver injury to decrease organ damage.

Gradual graft-cell repopulation with recipient cells following vasularized bone and limb allotransplantation

Little is known about the fate of graft cells following vascularized bone allografting. This study was conducted to define the process of graft-cell repopulation with recipient cells. Sixty-five vascularized tibial bone and 50 limb allotransplantations were performed in rat sex-mismatched pairs. FK 506 was used for immunosuppression. The ratio of donor and recipient cells in the graft was evaluated by semiquantitative polymerase chain reaction, using the Y-chromosome primers. Allografted bones had no rejection episodes. In the vascularized bone allograft model, donor-derived cells were gradually replaced by cells of recipient origin, such that by 24 weeks, they comprised only 10% of total cells. In the limb allograft model, male recipient cells were detected in female grafts not at 1 week but at 48 weeks posttransplantation. The ratio of recipient cells was more than 10% in the femur and tibia. Recipient-derived cells gradually migrated into the grafted bone cells with the passage of time.

Cell traffic between donor and recipient following rat limb allograft

Although cell traffic from the graft into the recipient and from the recipient into the graft had been noticed in allogeneic organ transplantation, little is known following whole-limb allografting. This study was conducted to define cell migration between donor and recipient. Sixty-seven vascularized hind limb allotransplantations were performed in rat sex-mismatched pairs and the recipient animals were treated with FK506 immunosuppression. The ratio of donor and recipient cells was evaluated by semi-quantitative PCR using the specific primers of the Y-chromosome. Allografted limbs had no rejection episode until the final assessment. The male recipient cells were detected in female limb grafts not at 1 week but at 48 weeks after transplantation. The male donor cells were detected in the humerus and tibia in the female recipient but not in the gastrocnemius muscle and leg skin. Our results demonstrated that recipient-derived cells gradually migrated into the grafted bone, muscle and skin cells with the duration of time. Donor-derived cells migrated into the healthy bones but not into the healthy muscle and skin. Because active regeneration occurs in the grafted limb to compensate graft damage secondary to ischemia and operative intervention, recipient-derived cells may mediate a muscular and dermo-epidermal renewal.

Severe preservation injury induces Il-6/STAT3 activation with lack of cell cycle progression after partial liver graft transplantation

Partial liver graft transplantation is a surgical advance developed to overcome severe donor shortage. Survival of these grafts involves recovery from cold ischemia and reperfusion (CIR) injury, immediate regeneration and maintenance of function. Here we examined the outcome of partial liver grafts in comparison to whole grafts following CIR injury. Lewis rats subjected to orthotopic liver transplantation (OLT) with whole grafts preserved in Viaspan were compared to rats receiving 50% and 30% grafts. Outcome was analyzed by survival and regeneration. Transplantation was associated with 100% survival for all grafts, whereas 16 h preservation resulted in 100%, 20% and 0% survival in animals receiving whole, 50% and 30% grafts, respectively. CIR induced increased IL-6 levels in 50% and 30% grafts, and activation of STAT3. Cell cycle progression (cyclin D1) and regeneration (BrdU) was initiated in all livers preserved for 1 or 8 h, but not in partial grafts preserved for 16 h. In conclusion, partial grafts recover from CIR injury through similar molecular pathways to whole grafts. Partial grafts with severe injury fail to achieve cellular proliferation despite the early initiating signals. This failure could be attributed to the impaired ability of the parenchyma to respond to initiating signals for regeneration.

Growth hormone/insulin-like growth factor 1 axis recovery after liver transplantation: a preliminary prospective study

Many studies on cirrhotic patients have shown that insulin-like growth factor 1 (IGF-1) plasma levels are related to the severity of liver dysfunction. This result suggests that IGF-1 is probably useful for monitoring liver function in the perioperative course of orthotopic liver transplantation (OLT). Growth hormone (GH), IGF-1 plasma levels, and routine liver function tests were measured in 15 adult cirrhotic patients undergoing OLT. Measurements were made at the beginning of the operation; during OLT; 24 hours after reperfusion; and in the morning on days 7, 30, and 90. Twenty age-matched healthy volunteers with normal liver function served as controls. The study group had significantly higher GH levels and lower IGF-1 levels in the preoperative period compared with the controls. All patients achieved a complete functional hepatic recovery 1 month after OLT, although in 6 of them, the graft had an initial poor function (Group-IPF). GH and IGF-1 levels achieved near normal range within 1 week after OLT, and they had no significant correlations with other routine biochemistry tests in this period. IGF-1 levels in Group-IPF rose more slowly than in the group with a normal recovery of graft function. Surprisingly, 24 hours after reperfusion, IGF-1 levels were higher in Group-IPF than in the group with normal graft function. In conclusion, the severe GH/IGF-1 axis impairment found in patients with end-stage cirrhosis reverted very rapidly in the first days after successful OLT. Such a quick, postoperative modulation of IGF-1 plasma level by the graft suggests that this hormone has the potential to become one of the early indicators of post-OLT liver function recovery.

Pattern of ischemia reperfusion injury in a mouse orthotopic liver transplant model

BACKGROUND

The molecular pathways of ischemic injury after liver transplantation are complex and difficult to dissect because of the presence of many variables. Transgenic and genetically deficient strains of mice provide ideal models for the study of the contribution of a single gene product in biological processes in vivo. Although well described in rats, prolonged preservation has not been studied in a mouse model of orthotopic liver transplantation (mOLT). The aim of this study was to establish a model of cold ischemia and reperfusion injury in mOLT and describe the pattern of the regenerative response to various lengths of cold storage.

MATERIALS AND METHODS

mOLT was performed using a syngeneic combination. Grafts were preserved at 4 degrees C in University of Wisconsin (Viaspan) solution for increasing periods of cold preservation. After cold storage, the liver grafts were transplanted and recipient survival was monitored. Hepatocellular injury was determined by histology, and the regenerative response was quantitated by interleukin 6 upregulation and DNA replication.

RESULTS

Long-term survival was 100%, 100%, 88%, and 0% for cold preservation of 1, 4, 8, and 16 h, respectively. Grafts with short preservation times (1 and 4 h) demonstrated limited injury and a weak regenerative response, with slight IL-6 early upregulation and minimal cell division. Eight hours of cold ischemia resulted in prominent injury and an intense regenerative response accompanied by significant IL-6 upregulation and DNA synthesis. Sixteen hours of storage resulted in all recipients succumbing to liver failure, with histology showing extensive hepatic necrosis.

CONCLUSIONS

This study demonstrated the feasibility of using the mOLT model for the study of molecular mechanisms associated with recovery from cold ischemia and reperfusion injury. Increasing lengths of cold ischemia correlate with progressive tissue damage whereas recovery is associated with a regenerative response that correlates with the severity of injury.

Dexamethasone inhibits early regenerative response of rat liver after cold preservation and transplantation

Regeneration is crucial for the recovery of hepatic mass following liver transplantation. Glucocorticoids, immunosuppressive and antiinflammatory agents commonly used in transplantation, are known to inhibit the expression of specific cytokines and growth factors. Some of these proteins, namely tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6), play a critical role in the initiation of liver regeneration. Following cold preservation and reperfusion of the transplanted liver, the normal recovery process is marked by increased expression of TNF-alpha and IL-6, followed by activation of cytokine-responsive transcription factors and progression of the cell cycle resulting in hepatocyte proliferation. We hypothesized that glucocorticoids may influence the repair mechanisms initiated after extended cold preservation and transplantation. Using a rat orthotopic liver transplant model, recipient animals were treated with dexamethasone at the time of transplantation of liver grafts with prolonged cold storage (16 hours). Treatment with dexamethasone suppressed and delayed the expression of TNF-alpha and IL-6 compared with animals receiving no treatment and attenuated downstream nuclear factor kappaB (NF-kappaB), signal transduction and activator of transcription 3 (STAT3), and activation protein 1 (AP-1) activation. This suppression was accompanied by poor cell-cycle progression, delayed cyclin D1 nuclear transposition, and impaired hepatocyte proliferation by BrdU uptake. Histologically, the liver grafts in treated animals demonstrated more injury than controls, which appeared to be necrosis, rather than apoptosis. In conclusion, these data provide evidence that the administration of glucocorticoids at the time of transplantation inhibits the initiation of the regenerative process and may have a deleterious effect on the recovery of liver grafts requiring significant regeneration. This may be particularly relevant for transplantation of partial liver grafts in the living donor setting.

Atrial natriuretic peptide preconditioning protects against hepatic preservation injury by attenuating necrotic and apoptotic cell death

BACKGROUND/AIMS

Preconditioning of livers with the atrial natriuretic peptide (ANP) markedly reduces hepatic ischemia-reperfusion injury. Aim of this study was to characterize the influence of ANP preconditioning on necrotic and apoptotic cell death and on proliferation.

METHODS

Rat livers were perfused with Krebs-Henseleit buffer with or without ANP or its second messenger analogue 8-Bromo cyclic guanosine monophosphate (8-Br cGMP) for 20 min, stored in cold University of Wisconsin solution (24 h), and reperfused for up to 120 min. Apoptosis and necrosis were determined using biochemical and morphological criteria, proliferation was assessed by Ki67 histochemistry.

RESULTS

Apoptosis peaked after 24 h of cold ischemia. Preconditioning with both ANP and 8-Br-cGMP significantly reduced caspase-3-like activity and the number of triphosphate nick-end labelling-positive cells. Reduction of apoptosis was significant for hepatocytes, but not for endothelial cells. After ischemia, degenerative cell changes were clearly reduced in ANP pretreated livers. After reperfusion, ANP preconditioning led to a significant reduction of necrotic hepatocytes and endothelial cells in periportal zones. Cell proliferation was not affected by preconditioning.

CONCLUSIONS

ANP reduces necrotic and apoptotic cell death without affecting the proliferation status. The protection takes place mainly in the periportal area and seems to be most prominent against necrosis of hepatocytes and endothelial cells during reperfusion.

Arterialized partial orthotopic liver transplantation in the mouse: a new model and evaluation of the critical liver mass

The availability of a model of partial orthotopic liver transplantation (OLT) in the mouse would be an important tool for studying injuries associated with transplantation. The goals of this study were three-fold: (1). to develop a model of partial OLT in the mouse, (2). to determine the minimal graft volume in this model, and (3). to define the injury associated with small volume incompatible with animal survival. Putative grafts of 30% and 50% were prepared. Their weight was 30 +/- 5% and 45 +/- 10%, respectively. Subsequently, 30% and 45% syngeneic partial liver grafts were orthotopically transplanted into C57BL/6 mice. Each recipient receiving a 45% graft survived permanently, whereas those receiving only a 30% graft volume died within 2 to 4 days of surgery. Serum transaminase levels normalized in the 45% graft group within 14 days after surgery. In this group, small foci of necrosis and mild steatosis were noted on histology at postoperative day 2, but no abnormalities were noted after 14 days and 100 days. In contrast, recipients who underwent transplantation with a 30% graft volume showed a comparable amount of necrosis and significant microvesicular steatosis in most hepatocytes 2 days after surgery. Hepatocyte proliferation was reduced in this group when compared with animals who underwent transplantation with a 45% graft volume. In conclusion, partial liver transplantation is feasible in the mouse with a critical graft volume ranging between 30% and 45%. Small liver grafts develop massive microvesicular steatosis and impaired regeneration rapidly leading to animal death.

Liver regeneration and surgical outcome in donors of right-lobe liver grafts

INTRODUCTION

Previous studies of healthy live-liver donors have suggested that complete liver regeneration occurs within a matter of weeks; however, there have been no long-term studies evaluating liver regeneration and few studies documenting long-term donor outcome.

MATERIALS AND METHODS

Fifty-one donors who provided right-lobe grafts underwent volumetric spiral computed tomography scans preoperatively and postoperatively at time intervals of 1 week and 1, 3, 6, and 12 months. Patient demographics, surgical data, and postoperative outcome were correlated with liver regeneration data. Donor surgical outcome was followed prospectively and recorded in a comprehensive database.

RESULTS

Thirty-three males and 18 females (mean age 36.0+/-9.6 years) provided 51 right-lobe grafts. Mean follow-up was 9.8+/-3.4 months. No donor operation was aborted, and surgical morbidity and mortality rates were 39% and 0%, respectively. Donor remnant liver volume was 49.4+/-5.7% of the original total liver volume (TLV). Overall liver regeneration was 83.3+/-9.0% of the TLV by 1 year. Female donors had significantly slower liver regrowth when compared with males at 12 months (79.8+/-9.3% vs. 85.6+/-8.2%, P<0.01). There was no effect of age, body mass index, operative time, estimated blood loss, postoperative complications, or perioperative liver function tests on liver regeneration.

DISCUSSION

Liver regeneration continues throughout the first postoperative year. Only one donor achieved complete liver regeneration during this time period; however, all donors have maintained normal liver function without long-term complications. Longer follow-up is needed to determine whether donors ever achieve original TLV.