Effects of warm ischemia time on biliary injury in rat liver transplantation

Anti-apoptotic treatment of warm ischemic male rat livers in machine perfusion improves symptoms of ischemia-reperfusion injury

Background

Liver donation after cardiac death (DCD) makes up a small percentage of the organs used in transplantation and poses a higher risk of graft loss compared to donation after brain death (DBD); this is a result of ischemia reperfusion for which the exact injury mechanisms are currently not fully understood. However, reperfusion injury has been shown to lead to necrosis as well as apoptosis through oxidative stress and mitochondrial dysfunction. In this work, we propose that use of the pro-survival, anti-apoptotic CEPT cocktail in post-ischemia normothermic machine perfusion (NMP) may improve recovery in rat livers subjected to extended durations of warm ischemia.

Materials and Methods

Livers procured from male Lewis rats were subjected to 90 min of warm ischemia, followed by 6 h of NMP where they were treated either with the survival-enhancing anti-apoptotic cocktail (CEPT), the vehicle (DMSO) or the base media with no additives.

Results

The CEPT-treated group exhibited lower expression of hepatic injury biomarkers, and improvement in a range of hepatocellular symptoms associated with the hepatic parenchyma, biliary epithelium and the sinusoidal endothelium, including recovery of bile secretion and lowered vascular resistance.

Conclusions

This study's findings suggest apoptosis plays a more significant role in ischemia-reperfusion injury than previously understood, and provide useful insight for further investigation of the specific underlying mechanisms and development of novel treatment methods.

Anti-apoptotic treatment of warm ischemic male rat livers in machine perfusion improves symptoms of ischemia-reperfusion injury

Liver donation after cardiac death (DCD) makes up a small percentage of the donor pool and poses a higher risk of graft loss compared to donation after brain death (DBD); this is a result of ischemia reperfusion for which the exact injury mechanisms are currently not fully understood. However, reperfusion injury has been shown to lead to necrosis as well as apoptosis at the cellular level. In this work, we propose that use of the pro-survival, anti-apoptotic CEPT cocktail in post-ischemia normothermic machine perfusion (NMP) may improve recovery in rat livers subjected to extended durations of warm ischemia. Livers procured from male lewis rats were subjected to 90 minutes of warm ischemia, followed by 6 hours of NMP where they were treated with the survival-enhancing anti-apoptotic cocktail (CEPT), the vehicle (DMSO) or the base media with no additives. The CEPT-treated group exhibited lower expression of hepatic injury biomarkers, and improvement in a range of hepatocellular functions associated with the hepatic parenchyma, biliary epithelium and especially the sinusoidal endothelium. This study's findings provide useful insight for further investigation of the extent of apoptotic contribution to ischemia reperfusion injury (IRI).

Risk Factors Related to Early Biliary Complications After Liver Transplantation: a Single-Center Analysis

BACKGROUND

The aim of this study was to evaluate the risk factors of early biliary complications (EBC) after liver transplantation (LT) and seek effective treatments based on our single-center experience.

METHODS

A total of 124 adult patients were divided into a non-EBC group and EBC group. EBC usually accounts for biliary leakage, biliary stricture, biliary stones, sphincter of Oddi dysfunction, and transient jaundice within 3 months after LT. Statistical analysis including logistic regression was performed to determine EBC risk factors. All procedures complied with the Helsinki Congress and the Declaration of Istanbul.

RESULTS

Non-EBC (n = 95) and EBC (n = 29) were finally compared, which had no difference in their general characteristics. EBC occurred in 29 patients (26.92%): 1 biliary hemorrhage (3.45%), 7 biliary leakage (24.13%), and 16 biliary stricture (55.18%), and 5 others (17.24%). Of all EBC patients, endoscopic retrograde cholangiopancreatography (68.96%) was higher used to deal with complications than conservative treatment (10.35%), percutaneous transhepatic cholangial drainage (17.24%), and surgical treatment (3.45%). On univariate analyses, risk factors for EBC were bilirubin (P = .014), warm ischemia time (WIT) (P = .020), second WIT (P = .042), and operative time (OT) (P = .033). On multivariate analysis, independent risk factors for BC were WIT (P = .011) and OT (P = .049).

CONCLUSIONS

The presence of WIT and OT were the independent risk factors for the development of EBC. In addition, we also confirmed that endoscopic retrograde cholangiopancreatography was beneficial and safe in the management of EBC after LT.

Ultrastructural changes of donor livers in liver transplantation indicate hepatocytes injury

The use of electron microscopy (EM) can provide details about cells and tissue down to the nanometer level. We aim to observe ultrastructural changes in the donor liver by EM and analyze the relationship with prognosis. Data from 89 liver transplant recipients were collected and analyzed for recovery of graft function. The results revealed significantly higher organelle injury scores in the primary liver graft nonfunction (PNF) group. High-score group had higher peak alanine aminotransferases, peak aspartate aminotransferases, and peak international normalized ratio (p = .041, .006 and .036, respectively). Warm ischemia time, score of rough endoplasmic reticulum and nucleus was larger in low-score group (p = .007, .006, and .025, respectively). Patients in high-score group had a significantly short survival time (60.0% vs. 92.9%, p = .0039). No significant difference was found in the analysis of 3-year survival rate (60% vs. 84.5%, p = .07). EM is one of feasible and effective strategy for evaluating the quality of donor liver and the patient's prognosis. Ultrastructural changes under EM indicate hepatocytes injury and a high score indicates a worse outcome in early period but does not affect long-term survival.

Early Experience of Pure Robotic Right Hepatectomy for Liver Donors in a Small-Volume Center

Background and Objectives

Living donor right hepatectomy has become the most common method of liver transplantation. With minimally invasive surgery, laparoscopic donor hepatectomy became possible, but with some limitations. Advancements in robotic technology made it possible to overcome these shortcomings and maximize the advantages of minimally invasive surgery in transplantation. For this reason, some centers have started robotic donor hepatectomy. Our study aimed to introduce our early experience of robotic donor right hepatectomy and investigate the feasibility of this surgery.

Methods

This study included 10 (30%) living donors who underwent pure robotic donor right hepatectomy at Dong-A University Hospital from January 1, 2020 to December 31, 2021. The medical records were analyzed to determine the short-term outcomes of these patients.

Results

The total operation time and warm ischemic time were 396.6 min ± 62.7 min and 19.7 min± 5.6 min, respectively. Moreover, there was no transfusion during the operation and no other port use and open conversion. The average real graft volume was 590 mL ± 73.5 mL, and the mean hospital stay was 8.7 d ± 2.6 d. There have been no specific complications noted in the donor group.

Conclusions

Based on our positive experience with pure robotic right hepatectomy for a liver donor, the robotic technique may be a new option for achieving minimally invasive surgery for a liver donor.

The role of graft reperfusion sequence in the development of non-anastomotic biliary strictures following orthotopic liver transplantation: A meta-analysis

BACKGROUND

Liver transplant is a potential cure for liver failure and hepatic malignancy but there are many techniques which have been described for vascular reconstruction. This study was to compare the prevalence of non-anastomotic biliary stricture and other surgical complications based on Clavien-Dindo scoring system, in initial portal reperfusion (sequential) versus simultaneous or initial artery reperfusion.

DATA SOURCES

Meta-analysis of published studies comparing the outcomes of both techniques was carried out. Data search was conducted across the major databases and studies were selected under the guidance of the Cochrane guidelines for systematic reviews and meta-analysis.

RESULTS

Seven studies were included to address the primary and the secondary outcomes. No statistical difference was found in the incidence of non-anastomotic biliary strictures (OR = 0.40; P = 0.14), regardless of reperfusion technique. The pooled estimate of the Clavien-Dindo grading of complications was not significantly different between the techniques, though Clavien-Dindo II complications were higher in the simultaneous or initial artery reperfusion group than the initial portal reperfusion group (OR = 2.73; P = 0.01). Similarly, there was no difference in the operative time, hospital stay and other outcomes addressed in this report.

CONCLUSIONS

The available evidence suggests that there is no significant difference demonstrated in the rate of non-anastomotic biliary strictures or other complications, between the two techniques, except for Clavien-Dindo II complications.

Modulation of Glutathione Hemostasis by Inhibition of 12/15-Lipoxygenase Prevents ROS-Mediated Cell Death after Hepatic Ischemia and Reperfusion

Background

Reactive oxygen species- (ROS-) mediated ischemia-reperfusion injury (IRI) detrimentally impacts liver transplantation and resection. 12/15-Lipoxygenase (12/15-LOX), an antagonistic protein of the glutathione peroxidase 4 (GPX4) signaling cascade, was proven to mediate cell death in postischemic cerebral and myocardial tissue. The aim of this study was to investigate the impact of 12/15-LOX inhibition on hepatic IRI.

Methods

Livers of C57BL/6 mice were exposed to 60 minutes of partial warm ischemia and 90 minutes of reperfusion after previous Baicalein administration, an inhibitor of 12/15-LOX. Tissue samples were analyzed by TUNEL assay, Western blot, and spectral photometry.

Results

TUNEL labeling showed a significant reduction of hepatic cell death following baicalein pretreatment. Western Blot analysis revealed a significant downregulation of Jun-amino-terminal-kinase (JNK), caspase-3, and poly-ADP-ribose-polymerase (PARP), besides considerably lowered p44/42-MAP-kinase (ERK1/2) expression after Baicalein administration. A significant elevation of glutathione oxidation was measured in Baicalein pretreated livers.

Conclusion

Our data show that inhibition of 12/15-lipoxygenase causes significant cell death reduction after hepatic ischemia and reperfusion by enhancing glutathione metabolism. We conclude that GPX4-dependent cell death signaling cascade might play a major role in development of hepatic IRI, in which the investigated proteins JNK, caspase-3, ERK1/2, and PARP might contribute to tissue damage.

Vagus Nerve Attenuates Hepatocyte Apoptosis upon Ischemia-Reperfusion via α7 Nicotinic Acetylcholine Receptor on Kupffer Cells in Mice

BACKGROUND

Hepatic ischemia-reperfusion (HIR) injury is a complication of liver surgery. As much as 50% of hepatocytes undergo apoptosis within the first 24 h of reperfusion. The neurotransmitters of the vagus nerve can activate α7 nicotinic acetylcholine receptor (α7nAChR) on macrophages. The function of Kupffer cells (KCs) determines HIR injury. We hypothesize that the vagus nerve could attenuate HIR-induced hepatocyte apoptosis by activating α7nAChR on KCs.

METHODS

Hepatic vagotomized C57BL/6J mice, KC-eliminated C57BL/6J mice, and α7nAChR mice were used for HIR. Primary KCs and hepatocytes were subjected to hypoxia/reoxygenation (HR). Liver injury, hepatocyte apoptosis, reactive oxygen species (ROS) production, and soluble CD163 were measured.

RESULTS

Hepatic vagotomy and α7nAChR caused higher levels of alanine transaminase and liver caspase-3 and -8 activity by HIR. Activating α7nAChR attenuated these changes in wild-type but not in the α7nAChR mice. Furthermore, activating α7nAChR diminished hepatic injury and reduced liver apoptosis by HIR in vagotomized mice. In vitro, activating α7nAChR reduced apoptosis of hepatocytes cocultured with KCs that suffered HR. Similar to the effects by catalase, activating α7nAChR on KCs reduced ROS and H2O2 by HR. The supernatant from KCs, with α7nAChR activated or catalase treated, prevented hepatocyte apoptosis by HR. Finally, KC elimination reduced HIR-induced H2O2 production in mice. Activating α7nAChR significantly attenuated soluble CD163 both in mice by HIR (serum: 240 ± 34 vs. 446 ± 72; mean ± SD; n = 8; P < 0.01) and in KCs by HR (supernatant: 4.23 ± 0.06 vs. 5.60 ± 0.18; n = 3; P < 0.01).

CONCLUSIONS

The vagus nerve could minimize HIR-induced liver apoptosis through activating α7nAChR on KCs possibly by preventing their excessive ROS production.

Liver grafts procured from donors after circulatory death have no increased risk of microthrombi formation

Microthrombi formation provoked by warm ischemia and vascular stasis is thought to increase the risk of nonanastomotic strictures (NAS) in liver grafts obtained by donation after circulatory death (DCD). Therefore, potentially harmful intraoperative thrombolytic therapy has been suggested as a preventive strategy against NAS. Here, we investigated whether there is histological evidence of microthrombi formation during graft preservation or directly after reperfusion in DCD livers and the development of NAS. Liver biopsies collected at different time points during graft preservation and after reperfusion were triple-stained with hematoxylin-eosin (H & E), von Willebrand factor VIII (VWF), and Fibrin Lendrum (FL) to evaluate the presence of microthrombi. In a first series of 282 sections obtained from multiple liver segments of discarded DCD grafts, microthrombi were only present in 1%-3% of the VWF stainings, without evidence of thrombus formation in paired H & E and FL stainings. Additionally, analysis of 132 sections obtained from matched, transplanted donation after brain death and DCD grafts showed no difference in microthrombi formation (11.3% versus 3.3% respectively; P = 0.082), and no relation to the development of NAS (P = 0.73). Furthermore, no microthrombi were present in perioperative biopsies in recipients who developed early hepatic artery thrombosis. Finally, the presence of microthrombi did not differ before or after additional flushing of the graft with preservation solution. In conclusion, the results of our study derogate from the hypothesis that DCD livers have an increased tendency to form microthrombi. It weakens the explanation that microthrombi formation is a main causal factor in the development of NAS in DCD and that recipients could benefit from intraoperative thrombolytic therapy to prevent NAS following liver transplantation. Liver Transplantation 22 1676-1687 2016 AASLD.

Donor gluconate rescues livers from uncontrolled donation after cardiac death

BACKGROUND

Ischemia from organ preservation or donation causes cells and tissues to swell owing to loss of energy-dependent mechanisms of control of cell volume. These volume changes cause substantial preservation injury, because preventing these changes by adding cell impermeants to preservation solutions decreases preservation injury. The objective of this study was to assess if this effect could be realized early in uncontrolled donation after cardiac death (DCD) livers by systemically loading donors with gluconate immediately after death to prevent accelerated swelling injury during the warm ischemia period before liver retrieval.

METHODS

Uncontrolled DCD rat livers were cold-stored in University of Wisconsin solution for 24 hours and reperfused on an isolated perfused liver (IPL) device for 2 hours or transplanted into a rat as an allograft for 7 days. Donors were pretreated with a solution of the impermeant gluconate or a saline control immediately after cardiac death. Livers were retrieved after 30 minutes.

RESULTS

In vivo, gluconate infusion in donors immediately before or after cardiac death prevented DCD-induced increases in total tissue water, decreased vascular resistance, increased oxygen consumption and synthesis of adenosine triphosphate, increased bile production, decreased lactate dehydrogenase release, and decreased histology injury scores after reperfusion on the IPL relative to saline-treated DCD controls. In the transplant model, donor gluconate pretreatment significantly decreased both alanine aminotransferase the first day after transplantation and total bilirubin the seventh day after transplantation.

CONCLUSION

Cell and tissue swelling plays a key role in preservation injury of uncontrolled DCD livers, which can be mitigated by early administration of gluconate solutions to the donor immediately after death.

Protective effects against hepatic ischemia-reperfusion injury after rat orthotopic liver transplantation because of BCL-2 overexpression

This study aims to investigate the protective effects and mechanism of recombinant adenovirus Ad.VSG-hBCL-2 towards ischemia/reperfusion injury in rat liver graft. Recombinant adenovirus Ad.VSG-hBCL-2 was injected into the donor rat liver of the experiment group through the portal vein, the laparotomy was performed for liver 36 h later, and the liver was save in lactated Ringer's solution at 4°C for 4 h, "two-cuff method" was used to perform the orthotopic liver transplantation. The bile secretion situations of two groups were observed 6 h after the portal vein reflow; the recipient rats were killed to detect the plasma levels of AST, ALT and LDH. And the expressions of Bcl-2 and TNF-α in liver tissue, and TUNEL assay was used to detect the apoptosis of liver tissue cells, electron microscopy was used to observe the changes of subcellular structures of liver tissue. 6 h after the surgery, the immunohistochemistry and Western Blot test showed that the Bcl-2 expression in the liver of the experiment group significantly increased than the control group, the bile secretion increased, the levels of AST, ALT and LDH were significantly lower, and the TNF-α expression increased significantly. The changes of cellular morphology of the experiment group were milder, and the apoptotic index was significantly lower than the control group. The portal vein-transfected recombinant adenovirus Ad.VSG-hBCL-2 could be effectively expressed in rat liver, and the high expressed Bcl-2 could reduce the ischemia/reperfusion injury in the transplanted liver.

Warm ischemia may damage peribiliary vascular plexus during DCD liver transplantation

Biliary complications cause significant morbidity and mortality in liver transplantation. Warm ischemia can induce biliary duct injury. This study aimed to investigate the effects of warm ischemia on the peribiliary vascular plexus in rat liver transplantation. A total of 102 Sprague-Dawley rats were divided into three groups: sham-operation group, non-ischemic group, and ischemic group. Liver transplantation was performed in both the non-ischemic group and the ischemic group. The animals were sacrificed on day 1, 3, 7, and 14 to collect the blood and liver samples. Serum levels of bile duct obstruction, viz, alkaline phosphatase and gamma-glutamyl transpeptidase, as well as direct and indirect bilirubin were measured. Liver biopsy samples were examined with hematoxylin-eosin staining and transmission electron microscopy. The levels of enzymes and bilirubin were significantly higher in the ischemic group than the non-ischemic group and sham-operated animals (P<0.05), with return to normal levels in the ischemic group after two weeks. Morphological examination showed microthrombi and endothelial damage in the bile ducts and the peribiliary vascular plexus of the ischemic group. Warm ischemia/reperfusion injury can damage the endothelium of the peribiliary vascular plexus, which might compromise the bile duct microcirculation and lead to ischemic cholangiopathy after liver transplantation.

Delayed rearterialization unlikely leads to nonanastomotic stricture but causes temporary injury on bile duct after liver transplantation

Nonanastomotic strictures (NAS) are common biliary complications after liver transplantation (LT). Delayed rearterialization induces biliary injury in several hours. However, whether this injury can be prolonged remains unknown. The correlation of this injury with NAS occurrence remains obscure. Different delayed rearterialization times were compared using a porcine LT model. Morphological and functional changes in bile canaliculus were evaluated by transmission electron microscopy and real-time PCR. Immunohistochemistry and TUNEL were performed to validate intrahepatic bile duct injury. Three months after LT was performed, biliary duct stricture was determined by cholangiography; the tissue of common bile duct was detected by real-time PCR. Bile canaliculi were impaired in early postoperative stage and then exacerbated as delayed rearterialization time was prolonged. Nevertheless, damaged bile canaliculi could fully recover in subsequent months. TNF-α and TGF-β expressions and apoptosis cell ratio increased in the intrahepatic bile duct only during early postoperative period in a time-dependent manner. No abnormality was observed by cholangiography and common bile duct examination after 3 months. Delayed rearterialization caused temporary injury to bile canaliculi and intrahepatic bile duct in a time-dependent manner. Injury could be fully treated in succeeding months. Solo delayed rearterialization cannot induce NAS after LT.

Sanguineous normothermic machine perfusion improves hemodynamics and biliary epithelial regeneration in donation after cardiac death porcine livers

The effects of normothermic machine perfusion (NMP) on the postreperfusion hemodynamics and extrahepatic biliary duct histology of donation after cardiac death (DCD) livers after transplantation have not been addressed thoroughly and represent the objective of this study. Ten livers (5 per group) with 60 minutes of warm ischemia were preserved via cold storage (CS) or sanguineous NMP for 10 hours, and then they were reperfused for 24 hours with whole blood in an isolated perfusion system to simulate transplantation. In our experiment, the arterial and portal vein flows were stable in the NMP group during the entire reperfusion simulation, whereas they decreased dramatically in the CS group after 16 hours of reperfusion (P < 0.05); these findings were consistent with severe parenchymal injury. Similarly, significant differences existed between the CS and NMP groups with respect to the release of hepatocellular enzymes, the volume of bile produced, and the levels of enzymes released into bile (P < 0.05). According to histology, CS livers presented with diffuse hepatocyte congestion, necrosis, intraparenchymal hemorrhaging, denudated biliary epithelium, and submucosal bile duct necrosis, whereas NMP livers showed very mild injury to the liver parenchyma and biliary architecture. Most importantly, Ki-67 staining in extrahepatic bile ducts showed biliary epithelial regeneration. In conclusion, our findings advance the knowledge of the postreperfusion events that characterize DCD livers and suggest NMP as a beneficial preservation modality that is able to improve biliary regeneration after a major ischemic event and may prevent the development of ischemic cholangiopathy in the setting of clinical transplantation.

Readmission after living donor liver transplantation: predictors, causes, and outcomes

BACKGROUND

Complications following liver transplantation requiring readmission may be serious and potentially life threatening. Most reports on readmission have been about after deceased donor liver transplantation (DDLT). We hypothesized that readmission after living donor liver transplantation (LDLT) is due to different reasons and analyzed our experience.

METHODS

We retrospectively analyzed the records of 172 consecutive patients who underwent liver transplantation at our institute between January 2010 and June 2012. The primary outcome measure was readmission. We classified readmission into early (<3 months after discharge) and late (>3 months).

RESULTS

The study population was 140 after excluding pediatric patients (12), DDLT recipients (2), and those who died during the index admission (18). Their median age was 42 years, and there were 117 males and 23 females. Thirty-eight patients were readmitted (56 episodes) after LDLT. There were 35 early and 21 late readmission episodes. The most common cause for early readmissions was infection (46 %) and that for late readmissions was biliary stricture (62 %). On univariate analysis, pretransplant portal vein thrombosis, more than one bile duct in the liver graft, revised arterial anastomosis or two arteries in the graft, and higher serum alkaline phosphatase levels at discharge were significantly associated with readmission. Readmission was also significantly associated with a higher overall mortality than non-readmission in which there was no mortality.

CONCLUSION

Pretransplant portal vein thrombosis, more than one bile duct in the liver graft, revision of the arterial anastomosis or two arteries in the graft, and higher serum alkaline phosphatase levels at discharge were significantly associated with readmission. Infective and biliary complications were the commonest causes of early and late readmission after LDLT.

A novel model for orthotopic liver transplantation in rats using hepatic rearterialization and biliary extradrainage system

BACKGROUND

Although the rat orthotopic liver transplantation (OLT) model has existed for many years, only a few models can be applied for dynamic bile collection. The aim of this study was to introduce a dependent rat OLT model with hepatic rearterialization and an expediently dynamic bile collection system.

METHODS

Forty-five male Sprague-Dawley rats were divided into the following three groups (n = 15 each): group A, OLT without hepatic rearterialization; group B, OLT with hepatic rearterialization; group C, OLT with hepatic rearterialization and a biliary extradrainage system. In groups B and C, a modified sleeve anastomosis between the donor common hepatic artery and the recipient proper hepatic artery was performed to restore the hepatic artery blood flow. In group C, after hepatic rearterialization, biliary extradrainage and jejunum stoma were performed to reestablish the bile flow, and a waistcoat-like external fixator was introduced to protect this system.

RESULTS

The surgical success rates in groups A, B, and C were 100% (15/15), 93% (14/15), and 93% (14/15), respectively. In groups B and C, the hepatic artery patency rates were 93% and 86% on postoperative day 3 and postoperative day 21, respectively. Also, the liver function and bile duct integrity were preserved better than that in group A. In group C, the biliary extradrainage system was well preserved and bile collection was easily performed.

CONCLUSIONS

The rat OLT model with hepatic rearterialization and a convenient biliary extradrainage system was satisfactory in maintaining the survival rate, hepatic artery patency rate, and recovery of graft function, so it can be applied in various studies after transplantation.