Cold ischemia affects sinusoidal endothelial cells while warm ischemia affects hepatocytes in liver transplantation

Evolution of morphological changes in donor livers undergoing normothermic machine perfusion

AIMS

There is a shortage of livers for transplantation in the United Kingdom; despite this, more than a fifth of those retrieved are not transplanted. Normothermic machine perfusion (NMP) allows a functional assessment of marginal organs using biochemical parameters. This study describes the histological changes in livers undergoing NMP.

METHODS AND RESULTS

A total of 170 biopsies taken pre-NMP, after 4 h of NMP, end-NMP and at implantation from 50 livers undergoing NMP as part of standard local transplant practice were retrospectively reviewed. Thirty-eight per cent had large droplet macrovesicular steatosis pre-NMP, which was associated with reduced organ utilisation, P = 0.096, subsequent extracellular fat and a neutrophilic reaction; 32% had small droplet macrovesicular steatosis pre-NMP suggestive of acute cellular stress, the severity of which was unchanged in 64% during the perfusion period. Those showing at least moderate hepatocellular necrosis at end-NMP were less likely to be transplanted (55 versus 24%, P = 0.0505). Variation in the extent of hepatocyte necrosis was seen between biopsies, with 43% of transplanted cases showing less hepatocyte necrosis at implantation compared to end-NMP and 21% more severe necrosis. Patchy portal inflammation was present in 96% of pre-NMP biopsies, although identifiable duct injury was rare and portal thrombi were not identified. Sinusoidal dilation pre-NMP was more frequent in donation after circulatory death donors, typically persisted during NMP although had improved by implantation in most and had resolved in cases with an early post-transplant biopsy.

CONCLUSIONS

Histological changes in NMP livers predominantly comprise donor-derived steatosis, stress-associated small droplet steatosis, retrieval- and procedure-associated sinusoidal dilation and ischaemic injury.

Normothermic Ex Vivo Liver Platform Using Porcine Slaughterhouse Livers for Disease Modeling

Metabolic and toxic liver disorders, such as fatty liver disease (steatosis) and drug-induced liver injury, are highly prevalent and potentially life-threatening. To allow for the study of these disorders from the early stages onward, without using experimental animals, we collected porcine livers in a slaughterhouse and perfused these livers normothermically. With our simplified protocol, the perfused slaughterhouse livers remained viable and functional over five hours of perfusion, as shown by hemodynamics, bile production, indocyanine green clearance, ammonia metabolism, gene expression and histology. As a proof-of-concept to study liver disorders, we show that an infusion of free fatty acids and acetaminophen results in early biochemical signs of liver damage, including reduced functionality. In conclusion, the present platform offers an accessible system to perform research in a functional, relevant large animal model while avoiding using experimental animals. With further improvements to the model, prolonged exposure could make this model a versatile tool for studying liver diseases and potential treatments.

Pre-Ischemic Hypothermic Oxygenated Perfusion Alleviates Protective Molecular Markers of Ischemia-Reperfusion Injury in Rat Liver

To expand the pool of organs, hypothermic oxygenated perfusion (HOPE), one of the most promising perfusion protocols, is currently performed after cold storage (CS) at transplant centers (HOPE-END). We investigated a new timing for HOPE, hypothesizing that performing HOPE before CS (HOPE-PRE) could boost mitochondrial protection allowing the graft to better cope with the accumulation of oxidative stress during CS. We analyzed liver injuries at 3 different levels. Histologic analysis demonstrated that, compared to classical CS (CTRL), the HOPE-PRE group showed significantly less ischemic necrosis compared to CTRL vs HOPE-END. From a biochemical standpoint, transaminases were lower after 2 hours of reperfusion in the CTRL vs HOPE-PRE group, which marked decreased liver injury. qPCR analysis on 37 genes involved in ischemia-reperfusion injury revealed protection in HOPE-PRE and HOPE-END compared to CTRL mediated through similar pathways. However, the CTRL vs HOPE-PRE group demonstrated an increased transcriptional level for protective genes compared to the CTRL vs HOPE-END group. This study provides insights on novel biomarkers that could be used in the clinic to better characterize graft quality improving transplantation outcomes.

Biomarkers of Early Liver Graft Damage in Circulatory Death and Brain Death Donors: A Propensity Score Matching Analysis

BACKGROUND

Donation after circulatory death (DCD) is related to a warm ischemia time and more complications compared with traditional donors (donation after brain death [DBD]).

METHODS

This study included biopsy samples retrospectively collected from November 2014 to December 2018 to compare histologic and biological markers of DCD and DBD liver grafts. The analysis includes marker of early apoptosis (p21), senescence (telomerase reverse transcriptase [TERT]), cell damage (caspase-3 active), endothelial damage (vascular endothelial growth factor), stem cell (CD90), hypoxia (HIF1A), inflammatory activation (COX-2), and cross-organ allograft rejection (CD44). A propensity score matching (PSM) was used to match patients receiving DCD livers to those receiving DBD livers. We analyzed the immunohistochemical initial liver damage-related warm ischemia time.

RESULTS

Positive staining expression of liver damage biomarkers (COX-2, CD44, TERT, HIF1A, and CD90) was found, but no significant differences were found between DCD and DBD and with ischemic cholangiopathy. After PSM, there was a significant relationship between CD90 and male donors (odds ratio [OR], 0.26; 95% confidence interval [CI], 0.07-0.91), TERT with donor sodium (OR, 1.11; 95% CI, 1.02-1.2), HIF1A with steatosis (OR, 0.33; 95% CI, 0.13-0.83), and CD44 with donor vasoactive drugs (OR, 0.36; 95% CI, 0.13-1) and glutamic oxaloacetic transaminase 1 week increase (OR, 1.01; 95% CI, 1-1.03).

CONCLUSIONS

DCD immunohistochemical initial liver damage was found to behave similarly to DBD. The increase in complications and cholangiopathy associated with warm ischemia could be related to a different later phenomenon.

Donor Diabetes and Prolonged Cold Ischemia Time Synergistically Increase the Risk of Graft Failure After Liver Transplantation

Background

Both prolonged cold ischemia time (CIT) and donor history of diabetes mellitus (DM) are associated with reduced graft survival after liver transplantation. However, it is unknown whether the adverse effect of prolonged CIT on posttransplant graft survival is more pronounced after transplant with DM versus non-DM donor grafts.

Methods

The study sample included 58 226 liver transplant recipients (2002-2015) from the Scientific Registry of Transplant Recipients. Multivariable Cox survival regression with interaction analysis was used to quantify the extent to which history of donor DM (n = 6478) potentiates the adverse effect of prolonged (≥8 hours) CIT (n = 18 287) on graft survival.

Results

Donor DM and CIT 8 hours or longer were each associated with increased risk of graft failure (GF) (adjusted hazard ratio [aHR], 1.19; 95% confidence interval [CI], 1.06-1.35 and aHR, 1.42; 95% CI, 1.32-1.53, respectively) compared with transplanted grafts without either risk factor. However, the combination of DM and CIT 8 hours or longer was associated with a higher risk of GF than either factor alone (aHR, 1.79; 95% CI, 1.55-2.06) and had a synergy index of 1.30. The interaction was significant on a multiplicative scale in the later postoperative period, days 31 to 365 (P = 0.047).

Conclusions

These results suggest that liver grafts from DM donors are more susceptible to the adverse effects of prolonged CIT than livers from non-DM donors. We need to be cognizant that they are more susceptible to ischemic injury, and this may be considered during the allocation process.

A sequential assessment of the preservation injury in porcine intestines

BACKGROUND

Clinical and experimental evidence strongly suggest that ischemia-reperfusion injury after intestinal transplantation has deleterious short- and long-term effects and finding means to reduce ischemia-reperfusion injury is a major research area. The anatomical and physiological similarities between the human and porcine digestive tract favor its use as a preclinical model for translational research. Intriguingly, no systematic appraisal of the development of the intestinal preservation injury in pigs is available.

MATERIALS AND METHODS

Intestinal procurement was performed in nine pigs using histidine-tryptophan-ketoglutarate solution as preservation fluid. Ileal biopsies were obtained after 8, 14, and 24 h of static cold storage (SCS), and the preservation injury was assessed morphologically (Chiu score) as well as on the molecular level. Tight junction (zonula occludens, claudin-3 and 4, tricellulin, and occludin) and adherens junctions (E-cadherin) proteins were studied using immunofluorescence and Western blot.

RESULTS

Eight hours of SCS induced minimal mucosal changes (Chiu grade 1) that advanced to significant subepithelial edema (Chiu grade 3) after 24 h; progressive Goblet cell depletion was also noted. Apoptosis (studied by cleaved caspase-3 staining significantly increased after 24 h of SCS. Significant molecular changes with decreasing expression of zonula occludens, tricellulin, and occludin were evident already after 8 h of SCS and continuously worsened. Claudin-3 and Claudin-4 and E-cadherin expression remained relatively unaltered during SCS.

CONCLUSIONS

Important molecular alterations precede histologic changes during SCS of the porcine intestine and may be used as more sensitive injury markers than histologic changes in intestinal ischemia and transplantation.

Warm ischemic injury is reflected in the release of injury markers during cold preservation of the human liver

BACKGROUND

Liver transplantation plays a pivotal role in the treatment of patients with end-stage liver disease. Despite excellent outcomes, the field is strained by a severe shortage of viable liver grafts. To meet high demands, attempts are made to increase the use of suboptimal livers by both pretransplant recovery and assessment of donor livers. Here we aim to assess hepatic injury in the measurement of routine markers in the post-ischemic flush effluent of discarded human liver with a wide warm ischemic range.

METHODS

Six human livers discarded for transplantation with variable warm and cold ischemia times were flushed at the end of preservation. The liver grafts were flushed with NaCl or Lactated Ringer's, 2 L through the portal vein and 1 L through the hepatic artery. The vena caval effluent was sampled and analyzed for biochemical markers of injury; lactate dehydrogenase (LDH), alanine transaminase (ALT), and alkaline phosphatase (ALP). Liver tissue biopsies were analyzed for ATP content and histologically (H&E) examined.

RESULTS

The duration of warm ischemia in the six livers correlated significantly to the concentration of LDH, ALT, and ALP in the effluent from the portal vein flush. No correlation was found with cold ischemia time. Tissue ATP content at the end of preservation correlated very strongly with the concentration of ALP in the arterial effluent (P<0.0007, R2 = 0.96).

CONCLUSION

Biochemical injury markers released during the cold preservation period were reflective of the duration of warm ischemic injury sustained prior to release of the markers, as well as the hepatic energy status. As such, assessment of the flush effluent at the end of cold preservation may be a useful tool in evaluating suboptimal livers prior to transplantation, particularly in situations with undeterminable ischemic durations.

Vitamin C treatment attenuates hemorrhagic shock related multi-organ injuries through the induction of heme oxygenase-1

BACKGROUND

Vitamin C (VitC) has recently been shown to exert beneficial effects, including protecting organ function and inhibiting inflammation, in various critical care conditions, but the specific mechanism remains unclear. Induction of heme oxygenase (HO)-1, a heat shock protein, has been shown to prevent organ injuries in hemorrhagic shock (HS) but the relationship between VitC and HO-1 are still ill-defined so far. Here we conducted a systemic in vivo study to investigate if VitC promoted HO-1 expression in multiple organs, and then tested if the HO-1 induction property of VitC was related to its organ protection and anti-inflammatory effect.

METHODS

Firstly, to determine the HO-1 induction property of VitC, the HO-1 level were measured in tissues including kidney, liver and lung of the normal and HS model of Sprague-Dawley (SD) rats after VitC treatment (100 mg/kg body weight). Secondly, to testify if VitC prevented HS related organ injuries via inducing HO-1, the HS model of rats were separately pre- and post-treated with VitC, and some of them also received Zinc protoporphyrin (Znpp), a specific HO-1 inhibitor. The HO-1 activity in tissues was tested; the organ injuries (as judged by histological changes in tissues and the biochemical indicators level in serum) and inflammatory response in tissues (as judged by the level of pro-inflammatory cytokines Tumor necrosis factor-α and Interleukin-6 ) were analyzed.

RESULTS

The HO-1 mRNA and protein level in kidney, liver, and lung were highly induced by VitC treatement under normal and HS conditions. The HO-1 activity in tissues was enhanced by both VitC pre- and post-treatment, which was shown to improve the organ injuries and inhibit the inflammatory response in the HS model of rats. Of note, the beneficial effects of VitC were abolished after HO-1 activity was blocked by Znpp.

CONCLUSIONS

VitC led to a profound induction of HO-1 in multiple organs including the kidney, liver and lung, and this property might be responsible for the organ protection and inflammation inhibitory effects of both pre- and post-treatment with VitC in HS.

Determination and extension of the limits to static cold storage using subnormothermic machine perfusion

BACKGROUND/AIMS

Static cold storage (SCS) of the liver for transplantation is limited by time. Continuation of metabolic activity leads to depletion of energy stores and loss of cellular function, which results in poor post-transplant function. Machine perfusion (MP) applied at the end of preservation may improve the viability of marginal liver grafts and provides information on the quality of the organ. We attempt to define the limits to SCS in terms of easily measurable perfusion parameters and investigate whether MP can improve liver viability. 


METHODS

Rat livers were cold-stored for 0, 24, 48, 72, and 120 h, after which they were treated with subnormothermic machine perfusion (SNMP). Livers cold-stored for 48 and 72 h were transplanted orthotopically with or without SNMP. During SNMP easily measurable parameters were monitored and adenosine triphosphate (ATP) content was measured following preservation and SNMP. 


RESULTS

ATP increased significantly during SNMP, but the recovered ATP content deteriorated with increased duration of SCS, with minimal improvement after 72 h of SCS. Vascular resistance during SNMP increased with extended preservation. After 48 h of SCS, orthotopic transplantation survival increased significantly from 50% to 100% with SNMP, but did not improve after 72 h. 


CONCLUSIONS

Vascular resistance and ATP recovery suggest a decrease in viability after 48 h of SCS. Survival data confirms the loss of post-transplant graft function and supports the use of ATP and vascular resistance as useful indicators. Further, we show that the recoverability of a liver using SNMP is limited to 48 h of SCS.

Intrahepatic complement activation, sinusoidal endothelial injury, and lactic acidosis are associated with initial poor function of the liver after transplantation

BACKGROUND

Changes in glucose metabolism in the liver during transplantation have been recently described using microdialysis. Here, these findings are correlated with histopathologic, immunohistochemical, and ultrastructural changes in liver.

METHODS

Microdialysis catheters were inserted into 15 human livers, which were perfused with isotonic solution, and samples of perfusate were analyzed before harvest, after storage, and after reperfusion. At each stage Menghini needle biopsy samples were taken and each studied using light and electron microscopy.

RESULTS

Six livers showed serum biochemical evidence of initial poor function. These livers had significantly more staining for complement fragment 4d (C4d) of both lobular and periportal hepatocytes. C4d-positive hepatocytes were also found in the liver during cold storage (3 of 15). These periportal hepatocytes also showed evidence of necrosis and were found to have intracellular neutrophils. Hepatocyte rounding in zone III, necrosis, and C4d staining in recipient were also significantly correlated with the degree of lactic acidosis during this phase. Intrahepatic lactic acidosis at all time points was significantly associated with sinusoidal endothelial cell injury after reperfusion. There were no correlations between glucose, pyruvate, and glycerol levels and histopathologic changes in the liver.

DISCUSSION

In the patients studied, the degree of C4d staining correlated with initial poor function and was associated with intrahepatic lactic acidosis in the donor during cold storage and after reperfusion. Complement activity in the liver during cold storage may be after in situ activation. Intrahepatic lactic acidosis is associated with sinusoidal endothelial cell and hepatocyte injury. The role of intrahepatic neutrophils is uncertain and could possibly be in response to cell necrosis.

General aspects and pitfalls in liver transplant pathology

Pathology in a liver transplant setting addresses four different topics: establishment of a definite diagnosis of the liver disease before listing for transplantation, evaluation of the donor liver with regard to pre-existing diseases, in particular macrovesicular steatosis and fibrosis, assessment of the hepatectomy specimen, and post-transplant biopsy evaluation. Of these, post-transplant biopsy evaluation is the most challenging and clinically the most relevant issue. It requires fast diagnoses to facilitate specific treatment and it has to incorporate a broad spectrum of differential diagnoses. Precise knowledge about rejection, post-transplant therapy, pathology of immunosuppression, and recurrence of the initially underlying liver disease including the characteristic time peaks and atypical histological presentations (e.g., fibrosing cholestatic hepatitis) is needed to evaluate specific and combined histological pictures of liver damage. For adequate interpretation of post-transplant biopsies the hepatopathologist has to be informed about the essential clinico-anamnestic aspects such as time course, medication, imaging results, and serology.

The first one thousand liver transplants in Turin: a single-center experience in Italy

The first Italian liver transplant center to reach the goal of 1000 procedures was Turin. The paper reports this single-center experience, highlighting the main changes that have occurred over time. From 1990 to 2002, 1000 consecutive liver transplants were performed in 910 patients, mainly cirrhotics. Surgical technique was based on the preservation of the retrohepatic vena cava of the recipient. The veno-venous bypass was used in 30 cases only and abandoned since 1997. Operating time, warm ischemia time and length of hospital stay significantly decreased over the years, while operating room extubation became routine. Immunosuppression pivoted on cyclosporine A. Management of retransplantations, marginal grafts, and of HCV-positive, HBV-positive and hepatocellular carcinoma recipients were optimized. Median follow-up of the patients was 41 months. Overall survival rates at 1, 5 and 10 years were 87%, 78% and 72% respectively. Survival rates obtained in the second half of the cases (1999-2002 period) were significantly better than those obtained in the first half (1990-1998 period) (90% vs. 83% at 1 year and 81% vs. 76% at 5 years respectively). Increasing experience in liver transplant surgery and postoperative care allowed standardization of the procedure and expansion of the activity, with parallel improvement of the results.

Liver Transplantation in Italy: Analysis of Risk Factors Associated with Graft Outcome

Objective

To analyze the graft outcome after liver transplantation in Italy in the years 1995 to 2000.

Methods

We performed a longitudinal study with follow-up at 3 months, 1 year, 3 years, and 5 years on 1987 liver grafts. The effect of several variables on graft survival was also analyzed.

Results

Several variables affect graft survival: Donor and recipient older age, gender mismatching, prolonged cold ischemia time, acute hepatic necrosis, and retransplantation are reported to significantly affect liver graft survival. Donors older than 60 years show a relative risk of 1.59 (95% CI, 1.23–2.05) compared with donors with an age between 19 and 60 years; recipients older than 50 years show a relative risk of 1.29 (95% CI, 1.04–1.60) compared with recipients aged 19 to 50 years. A cold ischemia time of 12 hours or longer doubled the risk of failure (relative risk = 2.01, 95% CI, 1.36–2.96) compared with a cold ischemia time of less than 6 hours.

Conclusions

The results show that the overall quality of liver transplantation in Italy is satisfying and comparable to the outcome reported by international registries. Follow-up studies on large numbers of liver transplants are useful to define predictors of outcome, and subsequently modify the criteria for organ allocation.

Prevention of hemorrhagic shock-induced lung injury by heme arginate treatment in rats

Hemorrhagic shock followed by resuscitation (HSR) induces oxidative stress, which leads to acute lung injury. Heme oxygenase (HO)-1 (EC 1.14.99.3), the rate-limiting enzyme in heme catabolism, is inducible by oxidative stress and is thought to play an important role in the protection from oxidative tissue injuries. In this study, we examined expression of HO-1 as well as tissue injuries in the lung, liver, and kidney after HSR in rats. We also pretreated animals with heme arginate (HA), a strong inducer of HO-1, and examined its effect on the HSR-induced lung injury. HO-1 expression significantly increased in the liver and kidney following HSR, while its expression in the lung was very low and unchanged after HSR. In contrast to HO-1 expression, tissue injury and tumor necrosis factor-alpha (TNF-alpha) gene expression was more prominent in the lung compared with those in the liver and kidney. HA pretreatment markedly induced HO-1 in pulmonary epithelial cells, and ameliorated the lung injury induced by HSR as judged by the improvement of histological changes, while it decreased TNF-alpha and inducible nitric oxide synthase gene expression, lung wet weight to dry weight ratio, and myeloperoxidase activity. In contrast, inhibition of HO-1 by tin-mesoporphyrin administration abolished the beneficial effect of HA pretreatment. These findings suggest that tissues with higher HO-1 may be better protected than those with lower HO-1 from oxidative tissue injury induced by HSR. Our findings also indicate that HA pretreatment can significantly suppress the HSR-induced lung injury by virtue of its ability to induce HO-1.

UW is superior to Celsior and HTK in the protection of human liver endothelial cells against preservation injury

Celsior solution (CS), a new preservation solution in thoracic organ transplantation, was evaluated for its efficacy in cold preservation of human liver endothelial cells (HLEC) and was compared to University of Wisconsin solution (UW) and histidine-tryptophan-ketoglutarate solution (HTK, Custodiol). HLEC cultures were preserved at 4 degrees C in CS, UW, and HTK, for 2, 6, 12, 24, and 48 hours, with 6 hours of reperfusion. Levels of lactate dehydrogenase (LDH), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and adenosine 5'-triphosphate (ATP) were measured after each interval of ischemia and the respective phase of reperfusion. Preservation injury of HLEC as measured by LDH release, intracellular ATP level, and MTT reduction were overall significantly (P <or= .01, P <or= .01, P < .05, respectively) lower in UW than in CS and HTK. CS demonstrates a modest superiority to HTK in HLEC preservation. Furthermore, cold preservation remains the main cause of preservation injury of HLEC regardless of the preservation solution used. Additionally, the maintenance of a high intracellular ATP level of HLEC after ischemia and reperfusion, as shown by UW, could be taken as a beneficial effect, particularly in long-term ischemia. In conclusion, our cell culture model reveals the order of efficacy to protect HLEC against preservation injury as: UW >> CS > HTK.

Protective effect of matrine on sinusoidal endothelial cells of rat liver isograft

AIM

To investigate the protection effect of matrine on cold ischemia and reperfusion injury of sinusoidal endothelial cells (SEC) of liver isograft.

METHODS

Two hundred and twenty-four SD rats were randomly divided into four groups: untreated group, low-dose treated group, high-dose treated group and sham operation group. After 5 hours of cold preservation with Ringer's solution, orthotopic liver transplantation was performed. At 1 h, 2 h and 4 h time-points after reperfusion, 6 rats were killed in each group to collect the serum sample and the middle lobe of liver for detection, and the other 8 rats were raised to study the one week survival rate post-transplantation.

RESULTS

All recipients in control group died within 48 hours, mostly between 10 to 20 hours, and matrine treatment increased one week survival rate to 75% in both treated groups. The level of Hylluronic Acid (HA) and glutamate pyruvate transaminase (ALT) decreased significantly with matrine treatment. And the expression of intercellular adhesion molecule-1 (ICAM-1) decreased significantly in both treated groups, and the pathological changes of SEC ameliorated.

CONCLUSION

Matrine can prevent SEC from cold ischemia and reperfusion injury in rat orthotopic liver transplantation.

Risk factors for and clinical course of non-anastomotic biliary strictures after liver transplantation

Non-anastomotic biliary stricture (NAS) formation is a major complication of liver transplantation. We prospectively determined the time to development of responsiveness to treatment, and clinical outcomes following NAS formation. In addition, an extensive analysis of the association of recipient, donor, and clinical variables with NAS formation was performed. A total of 749 consecutive patients was studied in a prospective, protocol-based fashion. Seventy-two patients (9.6%) developed NAS at a mean of 23.6 +/- 34.2 weeks post-transplantation. Non-anastomotic biliary stricture formation resolved in only 6% of affected patients. Although patient survival was not affected, retransplantation and graft loss rates were significantly greater in recipients who developed NAS. In contrast to previous reports, a pretransplant diagnosis of HCV was associated with a low frequency of NAS formation. The incidence of NAS was independently associated with pretransplant diagnoses of PSC and autoimmune hepatitis. Hepatic artery thrombosis, and prolonged warm and cold ischemia times were also independent risk factors for NAS formation. We conclude that NAS developed in approximately 10% of primary liver transplant recipients. A pretransplant diagnosis of autoimmune hepatitis has been identified as a novel independent risk factor for NAS formation. Development of NAS significantly attenuates graft but not patient survival.

Impairment of hepatosplanchnic oxygenation and increase of serum hyaluronate during normothermic and mild hypothermic cardiopulmonary bypass

Hepatic sinusoidal endothelial cells (SECs) are more vulnerable to hypoxia or hypothermia than hepatocytes. To test the hypothesis that hepatic venous desaturation during cardiopulmonary bypass (CPB) leads to impairment of SEC function, we studied the plasma kinetics of endogenous hyaluronate (HA), a sensitive indicator of SEC function, and hepatosplanchnic oxygenation during and after CPB. Twenty-five consecutive patients scheduled for elective coronary artery bypass graft surgery, who underwent normothermic (>35 degrees C; n = 15) or mild hypothermic (32 degrees C; n = 10) CPB participated in this study. A hepatic venous catheter was inserted into each patient to monitor hepatosplanchnic oxygenation and serum levels of HA concentration. Hepatic venous oxygen saturation decreased essentially to a similar degree during normothermic and mild hypothermic CPB. Hepatosplanchnic oxygen consumption and extraction increased during normothermic (P < 0.05), but not mild hypothermic, CPB. Both arterial and hepatic venous HA concentrations showed threefold increases during and after CPB in both groups. A positive correlation was found between hepatosplanchnic oxygen consumption and arterial HA concentrations during CPB, suggesting a role of changes in hepatosplanchnic oxygen metabolism in the mechanisms of increases in serum HA concentrations. The failure of the liver to increase HA extraction to a great degree suggests that a functional impairment of the SEC may contribute to the observed increase of serum HA.

IMPLICATIONS

Hepatic sinusoidal endothelial cells (SECs) are pivotal in the regulation of sinusoidal blood flow. This study showed that SEC function might be impaired during and after cardiopulmonary bypass, irrespective of the temperature management.

Extracorporeal suture technique for suprahepatic caval anastomosis in liver transplantation

BACKGROUND

During liver transplantation, an oversized graft or active bleeding in the hepatic area can make performance of the suprahepatic caval anastomosis extremely difficult or even impossible. In other instances, a brief as possible warm ischemia is desired to provide a marginal graft with maximum chances of good functioning.

METHODS

In order to manage those conditions, a suture technique was devised that allows the construction of a substantial part of the suprahepatic caval anastomosis keeping the graft outside the abdomen of the recipient.

RESULTS

Over a 12-month period, the technique was applied in 7 out of 148 transplants (5%). The 7 cases presented one or more of the following conditions: significant oversize mismatch (n = 6), active bleeding in the hepatic area (n = 1), and marginal graft (n = 4). Warm ischemia time averaged 27 minutes, a value not significantly different from the mean warm ischemia time of 25 minutes recorded in the easier transplants in which the conventional technique was used (P = 0.2467).

CONCLUSIONS

This extracorporeal suture technique allows construction of the suprahepatic caval anastomosis in critical situations arising during liver transplantation and avoidance of the prolonged warm ischemia that could be expected in such cases.

Role of hepatocytes and bile duct cells in preservation-reperfusion injury of liver grafts

In liver transplantation, it is currently hypothesized that nonparenchymal cell damage and/or activation is the major cause of preservation-related graft injury. Because parenchymal cells (hepatocytes) appear morphologically well preserved even after extended cold preservation, their injury after warm reperfusion is ascribed to the consequences of nonparenchymal cell damage and/or activation. However, accumulating evidence over the past decade indicated that the current hypothesis cannot fully explain preservation-related liver graft injury. We review data obtained in animal and human liver transplantation and isolated perfused animal livers, as well as isolated cell models to highlight growing evidence of the importance of hepatocyte disturbances in the pathogenesis of normal and fatty graft injury. Particular attention is given to preservation time-dependent decreases in high-energy adenine nucleotide levels in liver cells, a circumstance that (1) sensitizes hepatocytes to various stimuli and insults, (2) correlates well with graft function after liver transplantation, and (3) may also underlie the preservation time-dependent increase in endothelial cell damage. We also review damage to bile duct cells, which is increasingly being recognized as important in the long-lasting phase of reperfusion injury. The role of hydrophobic bile salts in that context is particularly assessed. Finally, a number of avenues aimed at preserving hepatocyte and bile duct cell integrity are discussed in the context of liver transplantation therapy as a complement to reducing nonparenchymal cell damage and/or activation.

Intrahepatic cholestasis following liver transplantation

Intrahepatic cholestasis following liver transplantation commonly occurs after liver transplantation and may be caused by infections, drugs such as cyclosporine and sulfonamides, and acute or chronic rejection. Less common causes such as fibrosing cholestatic hepatitis or recurrent primary biliary cirrhosis or primary sclerosing cholangitis may also be encountered. Biliary strictures may also be present. Although some disorders may be managed medically, others often require repeat liver transplantation. Prompt recognition and specific treatment can improve the outcome for liver transplant recipients.