Biliary complications after orthotopic liver transplantation. Curr Opin Organ Transplant. 2014;19:209-216. [PMID: 24752062 DOI: 10.1097/mot.0000000000000082]

Oxygenated versus non-oxygenated flush out during deceased donor liver procurement: The first proof-of-concept study in humans

BACKGROUND

Liver transplantation is used for treating end-stage liver disease, fulminant hepatitis, and oncological malignancies and organ shortage is a major limiting factor worldwide. The use of grafts based on extended donor criteria have become internationally accepted. Oxygenated machine perfusion technologies are the most recent advances in organ transplantation; however, it is only applied after a period of cold ischemia. Due to its high cost, we aimed to use a novel device, OxyFlush®, based on oxygenation of the preservation solution, applied during liver procurement targeting the maintenance of ATP during static cold storage (SCS).

METHODS

Twenty patients were randomly assigned to the OxyFlush or control group based on a 1:1 ratio. In the OxyFlush group, the perfusion solution was oxygenated with OxyFlush® device while the control group received a non-oxygenated solution. Liver and the common bile duct (CBD) biopsies were obtained at three different time points. The first was at the beginning of the procedure, the second during organ preparation, and the third after total liver reperfusion. Biopsies were analyzed, and adenosine triphosphate (ATP) levels and histological scores of the liver parenchyma and CBD were assessed. Postoperative laboratory tests were performed.

RESULTS

OxyFlush® was able to maintain ATP levels during SCS and improved the damage caused by the lack of oxygen in the CBD. However, OxyFlush® did not affect laboratory test results and histological findings of the parenchyma.

CONCLUSION

We present a novel low-cost device that is feasible and could represent a valuable tool in organ preservation during SCS.

The Long Road to Develop Custom-built Livers: Current Status of 3D Liver Bioprinting

Although liver transplantation is the gold-standard therapy for end-stage liver disease, the shortage of suitable organs results in only 25% of waitlisted patients undergoing transplants. Three-dimensional (3D) bioprinting is an emerging technology and a potential solution for personalized medicine applications. This review highlights existing 3D bioprinting technologies of liver tissues, current anatomical and physiological limitations to 3D bioprinting of a whole liver, and recent progress bringing this innovation closer to clinical use. We reviewed updated literature across multiple facets in 3D bioprinting, comparing laser, inkjet, and extrusion-based printing modalities, scaffolded versus scaffold-free systems, development of an oxygenated bioreactor, and challenges in establishing long-term viability of hepatic parenchyma and incorporating structurally and functionally robust vasculature and biliary systems. Advancements in liver organoid models have also increased their complexity and utility for liver disease modeling, pharmacologic testing, and regenerative medicine. Recent developments in 3D bioprinting techniques have improved the speed, anatomical, and physiological accuracy, and viability of 3D-bioprinted liver tissues. Optimization focusing on 3D bioprinting of the vascular system and bile duct has improved both the structural and functional accuracy of these models, which will be critical in the successful expansion of 3D-bioprinted liver tissues toward transplantable organs. With further dedicated research, patients with end-stage liver disease may soon be recipients of customized 3D-bioprinted livers, reducing or eliminating the need for immunosuppressive regimens.

Histological Assessment of the Bile Duct before Liver Transplantation: Does the Bile Duct Injury Score Predict Biliary Strictures?

INTRODUCTION

Histological injury to the biliary tree during organ preservation leads to biliary strictures after liver transplantation. The Bile Duct Injury (BDI) score was developed to assess histological injury and identify the grafts most likely to develop biliary strictures. The BDI score evaluates the bile duct mural stroma, peribiliary vascular plexus (PVP) and deep peribiliary glands (DPGs), which were correlated with post-transplant biliary strictures. However, the BDI score has not been externally validated. The aim of this study was to verify whether the BDI score could predict biliary strictures at our transplant centre.

METHODS

Brain-dead donor liver grafts transplanted at a single institution from March 2015 to June 2016 were included in this analysis. Bile duct biopsies were collected immediately before transplantation and assessed for bile duct injury by two blinded pathologists. The primary outcome was the development of clinically significant biliary strictures within 24 months post-transplant.

RESULTS

Fifty-seven grafts were included in the study which included 16 biliary strictures (28%). Using the BDI score, mural stromal, PVP and DPG injury did not correlate with biliary strictures including Non-Anastomotic Strictures. Severe inflammation (>50 leucocytes per HPF) was the only histological feature inversely correlated with the primary outcome (absent in the biliary stricture group vs. 41% in the no-stricture group, p = 0.001).

CONCLUSIONS

The current study highlights limitations of the histological assessment of bile duct injury. Although all grafts had bile duct injury, only inflammation was associated with biliary strictures. The BDI score was unable to predict post-transplant biliary strictures in our patient population.

Does an Additional Bile Duct Flush With Low-viscosity Preservation Solution Reduce Bile Duct Injury? A Single-blinded Randomized Clinical Trial

Biliary complications are a common cause of morbidity after liver transplantation and associated with bile duct injury. To reduce injury, a bile duct flush is performed with high-viscosity preservation solution. It has been suggested that an earlier additional bile duct flush with low-viscosity preservation solution may reduce bile duct injury and biliary complications. This study aimed to investigate whether an earlier additional bile duct flush would reduce bile duct injury or biliary complications.

Methods

A randomized trial was conducted using 64 liver grafts from brain dead donors. The control group received a bile duct flush with University of Wisconsin (UW) solution after donor hepatectomy. The intervention group received a bile duct flush using low-viscosity Marshall solution immediately after the onset of cold ischemia and a bile duct flush with University of Wisconsin solution after donor hepatectomy. The primary outcomes were the degree of histological bile duct injury, assessed using the bile duct injury score, and biliary complications within 24 mo of transplant.

Results

Bile duct injury scores were not different between the 2 groups. Similar rates of biliary complications occurred in the intervention group (31% [n = 9]) and controls (23% [n = 8]) (P = 0.573). No difference between groups was observed for anastomotic strictures (24% versus 20%, P = 0.766) or nonanastomotic strictures (7% versus 6%, P = 1.00).

Conclusions

This is the first randomized trial to investigate an additional bile duct flush using low-viscosity preservation solution during organ procurement. The findings from this study suggest that performing an earlier additional bile duct flush with Marshall solution does not prevent biliary complications and bile duct injury.

The role of T-tubes and abdominal drains on short-term outcomes in liver transplantation - A systematic review of the literature and expert panel recommendations

BACKGROUND

This systematic review and expert panel recommendation aims to answer the question regarding the routine use of T-tubes or abdominal drains to better manage complications and thereby improve outcomes after liver transplantation.

METHODS

Systematic review following PRISMA guidelines and recommendations using the GRADE approach derived from an international expert panel to assess the potential risks and benefits of T-tubes and intra-abdominal drainage in liver transplantation (CRD42021243036).

RESULTS

Of the 2996 screened records, 33 studies were included in the systematic review, of which 29 (six RCTs) assessed the use of T-tubes and four regarding surgical drains. Although some studies reported less strictures when using a T-tube, there was a trend toward more biliary complications with T-tubes, mainly related to biliary leakage. Due to the small number of studies, there was a paucity of evidence on the effect of abdominal drains with no clear benefit for or against the use of drainage. However, one study investigating the open vs. closed circuit drains found a significantly higher incidence of intra-abdominal infections when open-circuit drains were used.

CONCLUSIONS

Due to the potential risk of biliary leakage and infections, the routine intraoperative insertion of T-tubes is not recommended (Level of Evidence moderate - very low; grade of recommendation strong). However, a T-tube can be considered in cases at risk for biliary stenosis. Due to the scant evidence on abdominal drainage, no change in clinical practice in individual centers is recommended. (Level of Evidence very low; weak recommendation).

Incidents and risk factors of biliary complications after orthotropic liver transplantation

Biliary complications (BC) especially stenosis and strictures are the most common complications after orthotropic liver transplantation (OLT) procedure in adult recipients. The intention of this study was analyzed BC in 273 patients after OLT for the last 4 years in our department.Retrospective study of 273 patients underwent cadaveric donor liver transplantation between January 2014 and December 2017. Most of them (n = 268) have anastomosed bile duct in end to end, rest of them (n = 5) underwent hepaticojejunostomy. Statistical analysis was performed using Fischer exact test and Student t test. A P value <.05 was considered significant.BC were developed in 48/273 transplants (17.6%). The most frequent was biliary stricture (n = 42, 87.5%) followed by bile leak (n = 4, 8.3%) and choledocholitiasis (n = 2, 4.2%). Treatment was usually using endoscopic retrograde cholangiopancreatography. Recipients with hypotension during and after OLT treated by norepinephrine have a higher index of BC.Self-expanding metal stents implantation seems to be more effective than repeated balloon dilatation of anastomotic strictures with subsequent plastic biliary stent placement and associated with similar complication rate. Good fluid management against inotropic therapy may reduce risk of BC.

Biliary complications after liver transplantation: current perspectives and future strategies

Importance

Liver transplantation (LT) is a life-saving therapy for patients with end-stage liver disease and with acute liver failure, and it is associated with excellent outcomes and survival rates at 1 and 5 years. The incidence of biliary complications (BCs) after LT is reported to range from 5% to 20%, most of them occurring in the first three months, although they can occur also several years after transplantation.

Objective

The aim of this review is to summarize the available evidences on pathophysiology, risk factors, diagnosis and therapeutic management of BCs after LT.

Evidence Review

a literature review was performed of papers on this topic focusing on risk factors, classifications, diagnosis and treatment.

Findings

Principal risk factors include surgical techniques and donor's characteristics for biliary leakage and anastomotic biliary strictures and vascular alterations for non- anastomotic biliary strictures. MRCP is the gold standard both for intra- and extrahepatic BCs, while invasive cholangiography should be restricted for therapeutic uses or when MRCP is equivocal. About treatment, endoscopic techniques are the first line of treatment with success rates of 70-100%. The combined success rate of ERCP and PTBD overcome 90% of cases. Biliary leaks often resolve spontaneously, or with the positioning of a stent in ERCP for major bile leaks.

Conclusions and Relevance

BCs influence morbidity and mortality after LT, therefore further evidences are needed to identify novel possible risk factors, to understand if an immunological status that could lead to their development exists and to compare the effectiveness of innovative surgical and machine perfusion techniques.

Biliary Stones After Brain Dead Liver Transplantation Today: Rates, Risk Factors, Treatments, and Outcomes

AIMS

Our aim was to review the rate of biliary duct stones (BDS) after liver transplantation (LT), risk factors, and treatments, and to identify predictive factors for their onset.

METHODS

LTs performed in our center from 2004 to 2014 were studied. Risk factors for the onset of BDS were identified using univariable Cox's proportional hazards models.

RESULTS

Three hundred and sixty-four grafts with 317 duct-to-duct end-to-end biliary anastomosis on a T-tube and 47 hepaticojejunal anastomosis (HJ) were analyzed. BDS were identified in 13 of 364 (3.5%) grafts, including 10 duct-to-duct end-to-end biliary anastomosis on a T-tube grafts (3.2%) and 3 HJ grafts (6.4%). Predictive factors for BDS were biliary strictures (hazard ratio [HR] 9.94; 95% confidence interval [95% CI] 3.25-30.4), bilirubin (HR 1.04; 95% CI 1.01-1.06, for 1 unit increase), Model for End-Stage Liver Disease score (HR 1.07; 95% CI 1.01-1.14, for 1 unit increase), surgery time (HR 1.04; 95% CI 1.01-1.08, for 10-minute increase), hepatocellular disease (HR 8.3; 95% CI 1.09-64.0), hepatic artery thrombosis (HR 6.71; 95% CI 1.47-30.6), and retransplantation (HR 3.69; 95% CI 1.02-13.43). Among 51 grafts (14%) with biliary strictures, female sex was identified as a risk factor for BDS (HR 5.19; 95% CI 1.29-20.98). Multimodality treatment of BDS was often successful but open surgery was still needed in 23% of them. One-, 5-, and 10-year graft survival was not influenced by the onset of BDS.

CONCLUSION

Main predictive factor for BDS in liver grafts is biliary stricture. Recipient's age and body mass index failed to show any statistical importance. In grafts with biliary strictures, female sex is the main risk factor for BDS. In the absence of biliary strictures, hepatic artery thrombosis lead to an increase in the risk of BDS. Multimodality treatment of BDS is often successful. BDS do not influence outcome.

Impact of Machine Perfusion on Biliary Complications after Liver Transplantation

We describe in this review the different types of injuries caused to the biliary tree after liver transplantation. Furthermore, we explain underlying mechanisms and why oxygenated perfusion concepts could not only protect livers, but also repair high-risk grafts to prevent severe biliary complications and graft loss. Accordingly, we summarize experimental studies and clinical applications of machine liver perfusion with a focus on biliary complications after liver transplantation. Key points: (1) Acute inflammation with subsequent chronic ongoing liver inflammation and injury are the main triggers for cholangiocyte injury and biliary tree transformation, including non-anastomotic strictures; (2) Hypothermic oxygenated perfusion (HOPE) protects livers from initial oxidative injury at normothermic reperfusion after liver transplantation. This is a unique feature of a cold oxygenation approach, which is effective also end-ischemically, e.g., after cold storage, due to mitochondrial repair mechanisms. In contrast, normothermic oxygenated perfusion concepts protect by reducing cold ischemia, and are therefore most beneficial when applied instead of cold storage; (3) Due to less downstream activation of cholangiocytes, hypothermic oxygenated perfusion also significantly reduces the development of biliary strictures after liver transplantation.

S-Adenosylmethionine attenuates bile duct early warm ischemia reperfusion injury after rat liver transplantation

Warm ischemia reperfusion injury (IRI) plays a key role in biliary complication, which is a substantial vulnerability of liver transplantation. The early pathophysiological changes of IRI are characterized by an excessive inflammatory response. S-Adenosylmethionine (SAM) is an important metabolic intermediate that modulates inflammatory reactions; however, its role in bile duct warm IRI is not known. In this study, male rats were treated with or without SAM (170 μmol/kg body weight) after orthotopic autologous liver transplantation. The histopathological observations showed that bile duct injury in the IRI group was more serious than in the SAM group. The alanine aminotransferase (ALT), alkaline phosphatase (ALP) and direct bilirubin (DBIL) levels in the serum of the IRI group were significantly increased compared to the SAM group (P < .05). Simultaneously, SAM effectively improved the survival of the transplant recipients. Furthermore, the H₂O₂ and malondialdehyde (MDA) of the IRI group were much higher compared to the SAM group (P < .05). The GSH/GSSG ratio in the SAM group was significantly increased by SAM treatment compared to the IRI group (P < .05). SAM administration significantly inhibited macrophage infiltration in liver and bile duct tissues, down-regulated TNF-α levels and up-regulated IL-10 expression in bile duct tissues compared to the IRI group (P < .05). The number of apoptotic biliary epithelial cells and caspase-3-positive cells in IRI rat livers were much higher compared to those in SAM-treated rats at 24 h after liver transplantation (P < .05). These data suggested that SAM protected bile ducts against warm IRI by suppressing oxidative stress, inflammatory reactions and apoptosis of biliary epithelial cells after liver transplantation.α.

Clinical outcomes of donation after circulatory death liver transplantation in primary sclerosing cholangitis

BACKGROUND & AIM

Primary sclerosing cholangitis (PSC) is a progressive fibro-inflammatory cholangiopathy for which liver transplantation is the only life-extending intervention. These patients may benefit from accepting liver donation after circulatory death (DCD), however their subsequent outcome is unknown. The aim of this study was to determine the clinical impact of using DCD liver grafts in patients specifically undergoing transplantation for PSC.

METHODS

Clinical outcomes were prospectively evaluated in PSC patients undergoing transplantation from 2006 to 2016 stratified by donor type (DCD, n=35 vs. donation after brainstem death [DBD], n=108).

RESULTS

In liver transplantation for PSC; operating time, days requiring critical care support, total ventilator days, incidence of acute kidney injury, need for renal replacement therapy (RRT) or total days requiring RRT were not significantly different between DCD vs. DBD recipients. Although the incidence of ischaemic-type biliary lesions was greater in the DCD group (incidence rate [IR]: 4.4 vs. 0 cases/100-patient-years; p<0.001) there was no increased risk of post-transplant biliary strictures overall (hazard ratio [HR]: 1.20, 0.58-2.46; p=0.624), or in sub-analysis specific to anastomotic strictures or recurrent PSC, between donor types. Graft loss and mortality rates were not significantly different following transplantation with DCD vs. DBD livers (IR: 3.6 vs. 3.1 cases/100-patient-years, p=0.34; and 3.9 vs. 4.7, p=0.6; respectively). DCD liver transplantation in PSC did not impart a heightened risk of graft loss (HR: 1.69, 0.58-4.95, p=0.341) or patient mortality (0.75, 0.25-2.21, p=0.598).

CONCLUSION

Transplantation with DCD (vs. DBD) livers in PSC patients does not impact graft loss or patient survival. In an era of organ shortage, DCD grafts represent a viable therapeutic option for liver transplantation in PSC patients. Lay summary: This study examines the impact of liver transplantation in primary sclerosing cholangitis (PSC) with organs donated after circulatory death (DCD), compared to donation after brainstem death (DBD). We show that in appropriately selected patients, the outcomes for DCD transplantation mirror those using DBD livers, with no significant differences in complication rate, patient survival or transplanted liver survival. In an era of organ shortage and increasing wait-list times, DCD livers represent a potential treatment option for transplantation in PSC.

Comparison of Postoperative Outcomes Between Donation After Circulatory Death and Donation After Brain Death Liver Transplantation Using the Comprehensive Complication Index

OBJECTIVE

To test the total burden of complications in the early postoperative period after liver transplantation (LT) between donation after circulatory death (DCD) and donation after brain death (DBD) grafts with the novel Comprehensive Complication Index (CCI).

BACKGROUND

LT is complex surgery and the increasing use of high-risk grafts is pressuring current postoperative outcomes. DCD grafts in particular are associated with ischemic-type biliary lesions (ITBL) with subsequent impaired graft survival rates.

METHODS

Retrospective single-center study of all LT since the start of DCD program (2001-2015). CCI (at hospital discharge and after 6 months) was the result of all complications weighted by their Clavien-Dindo grade. A multiple logistic regression model was used to identify factors associated with a complex postoperative course (CCI at 6 months >60).

RESULTS

In total, 441 cases were included: 115 DCD and 326 DBD grafts. Median in-hospital CCI was comparable for both groups (DCD 38.2; DBD 36.7; P = 0.429). Six-month postoperative median CCI was significantly higher for DCD grafts (53.4 vs 47.2; P = 0.041). Moreover, more DCD recipients underwent retransplantation for ITBL in this period (4% vs 1%; P = 0.031). Logistic regression identified recipient BMI (P = 0.046), recipient warm ischemia time (odds ratio, OR, 1.032; 95% CI, 1.008-1.056; P = 0.008), and DCD graft (OR 3.913; 95% CI 1.200-12.767; P = 0.024) as risk factors for a CCI >60.

CONCLUSIONS

This analysis shows a comparable complication rate during the index hospital stay for DCD and DBD LT, but the CCI increases significantly for DCD recipients in 6 months after transplantation. Reduction of biliary complications, especially ITBL, is needed to improve the outcomes for DCD grafts.

Early and Late Factors Impacting Patient and Graft Outcome in Pediatric Liver Transplantation: Summary of an ESPGHAN Monothematic Conference

As pediatric liver transplantation comes of age, experts gathered to discuss current paradigms and define gaps in knowledge warranting research to further improve patient and graft outcomes. Identified areas ripe for collaborative research include understanding the molecular and cellular mechanisms of tolerance and the role of donor-specific antibodies, considering ways to expand donor pool, minimizing long-term side effects of immunosuppression, and fine-tuning surgical techniques to minimize biliary and vascular complications.

Liver Preservation by Aortic Perfusion Alone Compared With Preservation by Aortic Perfusion and Additional Arterial Ex Situ Back-Table Perfusion With Histidine-Tryptophan-Ketoglutarate Solution: A Prospective, Randomized, Controlled, Multicenter Study

Background

Arterial ex situ back-table perfusion (BP) reportedly reduces ischemic-type biliary lesion after liver transplantation. We aimed to verify these findings in a prospective investigation.

Methods

Our prospective, randomized, controlled, multicenter study involved livers retrieved from patients in 2 German regions, and compared the outcomes of standard aortic perfusion to those of aortic perfusion combined with arterial ex situ BP. The primary endpoint was the incidence of ischemic-type biliary lesions over a follow-up of 2 years after liver transplantation, whereas secondary endpoints included 2-year graft survival, initial graft damage as reflected by transaminase levels, and functional biliary parameters at 6 months after transplantation.

Results

A total of 75 livers preserved via standard aortic perfusion and 75 preserved via standard aortic perfusion plus arterial BP were treated using a standardized protocol. The incidence of clinically apparent biliary lesions after liver transplantation (n = 9 for both groups; P = 0.947), the 2-year graft survival rate (standard aortic perfusion, 74%; standard aortic perfusion plus arterial BP, 68%; P = 0.34), and incidence of initial graft injury did not differ between the 2 perfusion modes. Although 33 of the 77 patients with cholangiography workups exhibited injured bile ducts, only 10 had clinical symptoms.

Conclusions

Contrary to previous findings, the present study indicated that additional ex situ BP did not prevent ischemic-type biliary lesions or ischemia-reperfusion injury after liver transplantation. Moreover, there was considerable discrepancy between cholangiography findings regarding bile duct changes and clinically apparent cholangiopathy after transplantation, which should be considered when assessing ischemic-type biliary lesions.

Endoscopic management of bile leaks after liver transplantation: An analysis of two high-volume transplant centers

Background

Bile leak after liver transplantation (LT) is commonly treated with endoscopic retrograde cholangiopancreatography (ERCP); however, there are limited data regarding the optimal treatment strategy.

Objective

We aimed to examine the role of ERCP in LT recipients with bile leaks at two large institutions.

Methods

We reviewed all ERCPs performed in LT recipients with bile leak and duct-to-duct biliary anastomosis at two high-volume transplant centers.

Results

Eighty patients were included. Forty-seven (59%) patients underwent ERCP with plastic stent placement (with or without sphincterotomy) and 33 patients (41%) underwent sphincterotomy alone. Complete resolution was obtained in 94% of the stent group vs. 58% of the sphincterotomy group (p < 0.01). There was no difference in three-month survival among both groups. Percutaneous transhepatic therapy and surgery were required in 4% and 6% in the stent group vs. 12% and 42% in the sphincterotomy group, respectively (p = 0.22 and p < 0.001). The only predictive factor of bile leak resolution was stent placement.

Conclusion

ERCP with plastic stent placement is highly successful and more effective than sphincterotomy alone for post-LT bile leak treatment. These results indicate that ERCP and plastic stent placement should be considered the standard of care for the treatment of bile leaks in LT.

Biliary complications following liver transplantation: Single-center experience over three decades and recent risk factors

AIM

To identify independent risk factors for biliary complications in a center with three decades of experience in liver transplantation.

METHODS

A total of 1607 consecutive liver transplantations were analyzed in a retrospective study. Detailed subset analysis was performed in 417 patients, which have been transplanted since the introduction of Model of End-Stage Liver Disease (MELD)-based liver allocation. Risk factors for the onset of anastomotic biliary complications were identified with multivariable binary logistic regression analyses. The identified risk factors in regression analyses were compiled into a prognostic model. The applicability was evaluated with receiver operating characteristic curve analyses. Furthermore, Kaplan-Meier analyses with the log rank test were applied where appropriate.

RESULTS

Biliary complications were observed in 227 cases (14.1%). Four hundred and seventeen (26%) transplantations were performed after the introduction of MELD-based donor organ allocation. Since then, 21% (n = 89) of the patients suffered from biliary complications, which are further categorized into anastomotic bile leaks [46% (n = 41)], anastomotic strictures [25% (n = 22)], cholangitis [8% (n = 7)] and non-anastomotic strictures [3% (n = 3)]. The remaining 18% (n = 16) were not further classified. After adjustment for all univariably significant variables, the recipient MELD-score at transplantation (P = 0.006; OR = 1.035; 95%CI: 1.010-1.060), the development of hepatic artery thrombosis post-operatively (P = 0.019; OR = 3.543; 95%CI: 1.233-10.178), as well as the donor creatinine prior to explantation (P = 0.010; OR = 1.003; 95%CI: 1.001-1.006) were revealed as independent risk factors for biliary complications. The compilation of these identified risk factors into a prognostic model was shown to have good prognostic abilities in the investigated cohort with an area under the receiver operating curve of 0.702.

CONCLUSION

The parallel occurrence of high recipient MELD and impaired donor kidney function should be avoided. Risk is especially increased when post-transplant hepatic artery thrombosis occurs.

Oxygenated Hypothermic Machine Perfusion After Static Cold Storage Improves Hepatobiliary Function of Extended Criteria Donor Livers

BACKGROUND

The mechanism through which oxygenated hypothermic machine perfusion (HMP) improves viability of human extended criteria donor (ECD) livers is not well known. Aim of this study was to examine the benefits of oxygenated HMP after static cold storage (SCS).

METHODS

Eighteen ECD livers that were declined for transplantation underwent ex situ viability testing using normothermic (37 °C) machine perfusion (NMP) after traditional SCS (0 °C-4 °C) for 7 to 9 hours. In the intervention group (n = 6), livers underwent 2 hours of oxygenated HMP (at 12 °C) after SCS and before NMP. Twelve control livers underwent NMP without oxygenated HMP after SCS.

RESULTS

During HMP, hepatic ATP content increased greater than 15-fold, and levels remained significantly higher during the first 4 hours of NMP in the HMP group, compared with controls. Cumulative bile production and biliary secretion of bilirubin and bicarbonate were significantly higher after HMP, compared with controls. In addition, the levels of lactate and glucose were less elevated after HMP compared with SCS preservation alone. In contrast, there were no differences in levels of hepatobiliary injury markers AST, ALT, LDH, and gamma-GT after 6 hours of NMP. Hepatic histology at baseline and after 6 hours of NMP revealed no differences in the amount of ischemic necrosis between both groups.

CONCLUSIONS

Two hours of oxygenated HMP after traditional SCS restores hepatic ATP levels and improves hepatobiliary function but does not reduce (preexisting) hepatobiliary injury in ECD livers.

Functional Immune Anatomy of the Liver-As an Allograft

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative "strength" of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell-mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell-mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The "balance" is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.

Split liver transplantation: Report of right and left graft outcomes from a multicenter Argentinean group

Grafts from split livers (SLs) constitute an accepted approach to expand the donor pool. Over the last 5 years, most Argentinean centers have shown significant interest in increasing the use of this technique. The purpose of this article is to describe and analyze the outcomes of right-side grafts (RSGs) and left-side grafts (LSGs) from a multicenter study. The multicenter retrospective study included data from 111 recipients of SL grafts from between January 1, 2009 and December 31, 2013. Incidence of surgical complications, patient and graft survival, and factors that affected RSG and LSG survival were analyzed. Grafts types were 57 LSG and 54 RSG. Median follow-up times for LSG and RSG were 46 and 42 months, respectively. The 36-month patient and graft survivals for LSG were 83% and 79%, respectively, and for RSG were 78% and 69%, respectively. Retransplantation rates for LSG and RSG were 3.5% and 11%, respectively. Arterial complications were the most common cause of early retransplantation (less than 12 months). Cold ischemia time (CIT) longer than 10 hours and the use of high-risk donors (age ≥ 40 years or body mass index ≥ 30 kg/m2 or ≥ 5 days intensive care unit stay) were independent factors for diminished graft survival in RSG. None of the analyzed variables were associated with worse graft survival in LSG. Biliary complications were the most frequent complications in both groups (57% in LSG and 33% in RSG). Partial grafts obtained from liver splitting are an excellent option for patients in need of liver transplantation and have the potential to alleviate the organ shortage. Adequate donor selection and reducing CIT are crucial for optimizing results.

Role of endoscopy in the conservative management of biliary complications after deceased donor liver transplantation

The clinical outcome of patients receiving liver transplantation could be significantly affected by biliary complications, including strictures, leaks, stones and bilomas; early diagnosis and treatment of these conditions lead to markedly reduction in morbidity and mortality. Therapeutic gold standard is represented by conservative approaches, both endoscopic and percutaneous, based on the type of biliary reconstruction, the local availability of the procedures and specific expertise. In patients with previous transplantation, the difficult biliary access and the possible presence of concomitant complications (mainly strictures) further restrict the efficacy of the endoscopic and percutaneous treatments; on the other hand, surgery should generally be avoided because of the even increased morbidity and mortality due to technical and clinical issues. Here we review the most common biliary complications occurring after liver transplantation and discuss available treatment options including future perspectives such as endoscopic ultrasound-guided biliary access in patients with Roux-en-Y choledocho-jejunostomy or extracorporeal shock wave lithotripsy for difficult stones.

Biliary complications in liver transplantation: Impact of anastomotic technique and ischemic time on short- and long-term outcome

AIM: To elucidate the impact of various donor recipient and transplant factors on the development of biliary complications after liver transplantation.

METHODS: We retrospectively reviewed 200 patients of our newly established liver transplantation (LT) program, who received full size liver graft. Biliary reconstruction was performed by side-to-side (SS), end-to-end (EE) anastomosis or hepeaticojejunostomy (HJ). Biliary complications (BC), anastomotic stenosis, bile leak, papillary stenosis, biliary drain complication, ischemic type biliary lesion (ITBL) were evaluated by studying patient records, corresponding radiologic imaging and reports of interventional procedures [e.g., endoscopic retrograde cholangiopancreatography (ERCP)]. Laboratory results included alanine aminotransferase (ALT), gammaglutamyltransferase and direct/indirect bilirubin with focus on the first and fifth postoperative day, six weeks after LT. The routinely employed external bile drain was examined by a routine cholangiography on the fifth postoperative day and six weeks after transplantation as a standard procedure, but also whenever clinically indicated. If necessary, interventional (e.g., ERCP) or surgical therapy was performed. In case of biliary complication, patients were selected, assigned to different complication-groups and subsequently reviewed in detail. To evaluate the patients outcome, we focussed on appearance of postoperative/post-interventional cholangitis, need for rehospitalisation, retransplantation, ITBL or death caused by BC.

RESULTS: A total of 200 patients [age: 56 (19-72), alcoholic cirrhosis: n = 64 (32%), hepatocellular carcinoma: n = 40 (20%), acute liver failure: n = 23 (11.5%), cryptogenic cirrhosis: n = 22 (11%), hepatitis B virus /hepatitis C virus cirrhosis: n = 13 (6.5%), primary sclerosing cholangitis: n = 13 (6.5%), others: n = 25 (12.5%) were included. The median follow-up was 27 mo until June 2015. The overall biliary complication rate was 37.5% (n = 75) with anastomotic strictures (AS): n = 38 (19%), bile leak (BL): n = 12 (6%), biliary drain complication: n = 12 (6%); papillary stenosis (PS): n = 7 (3.5%), ITBL: n = 6 (3%). Clinically relevant were only 19% (n = 38). We established a comprehensive classification for AS with four grades according to clinical relevance. The reconstruction techniques [SS: n = 164, EE: n = 18, HJ: n = 18] showed no significant impact on the development of BCs in general (all n < 0.05), whereas in the HJ group significantly less AS were found (P = 0.031). The length of donor intensive care unit stay over 6 d had a significant influence on BC development (P = 0.007, HR = 2.85; 95%CI: 1.33-6.08) in the binary logistic regression model, whereas other reviewed variables had not [warm ischemic time > 45 min (P = 0.543), cold ischemic time > 10 h (P = 0.114), ALT init > 1500 U/L (P = 0.631), bilirubin init > 5 mg/dL (P = 0.595), donor age > 65 (P = 0.244), donor sex (P = 0.068), rescue organ (P = 0.971)]. 13% (n = 10) of BCs had no therapeutic consequences, 36% (n = 27) resulted in repeated lab control, 40% (n = 30) received ERCP and 11% (n = 8) surgical therapy. Fifteen (7.5%) patients developed cholangitis [AS (n = 6), ITBL (n = 5), PS (n = 3), biliary lesion BL (n = 1)]. One patient developed ITBL twelve months after LT and subsequently needed retransplantation. Rehospitalisation rate was 10.5 % (n= 21) [AS (n = 11), ITBL (n = 5), PS (n = 3), BL (n = 1)] with intervention or reinterventional therapy as main reasons. Retransplantation was performed in 5 (2.5%) patients [ITBL (n = 1), acute liver injury (ALI) by organ rejection (n = 3), ALI by occlusion of hepatic artery (n = 1)]. In total 21 (10.5%) patients died within the follow-up period. Out of these, one patient with AS developed severe fatal chologenic sepsis after ERCP.

CONCLUSION: In our data biliary reconstruction technique and ischemic times seem to have little impact on the development of BCs.

Molecular hydrogen attenuates hypoxia/reoxygenation injury of intrahepatic cholangiocytes by activating Nrf2 expression

Hypoxia/reoxygenation (H/R) injury of cholangiocytes causes serious biliary complications during hepatobiliary surgeries. Molecular hydrogen (H2) has been shown to be effective in protecting various cells and organs against oxidative stress injury. Human liver cholangiocytes were used to determine the potential protective effects of hydrogen against cholangiocyte H/R injury and explore the underlying mechanisms. We found that H2 ameliorated H/R-induced cholangiocytes apoptosis. Our study revealed that H2 activated NF-E2-related factor 2 (Nrf2) and downstream cytoprotective protein expression. However, the protective function of H2 was abolished when Nrf2 was silenced. Apoptosis in cholangiocytes isolated from a rat model of liver ischemia/reperfusion injury indicated that H2 significantly attenuates ischemia/reperfusion cholangiocyte injury in vivo. In conclusion, our study shows that H2 protects intrahepatic cholangiocytes from hypoxia/reoxygenation-induced apoptosis in vitro or in vivo, and this phenomenon may depend on activating Nrf2 expression.

Endoscopic management of benign biliary strictures

Benign biliary strictures are a common indication for endoscopic retrograde cholangiopancreatography (ERCP). Endoscopic management has evolved over the last 2 decades as the current standard of care. The most common etiologies of strictures encountered are following surgery and those related to chronic pancreatitis. High-quality cross-sectional imaging provides a road map for endoscopic management. Currently, sequential placement of multiple plastic biliary stents represents the preferred approach. There is an increasing role for the treatment of these strictures using covered metal stents, but due to conflicting reports of efficacies as well as cost and complications, this approach should only be entertained following careful consideration. Optimal management of strictures is best achieved using a team approach with the surgeon and interventional radiologist playing an important role.

Machine perfusion in liver transplantation as a tool to prevent non-anastomotic biliary strictures: Rationale, current evidence and future directions

The high incidence of non-anastomotic biliary strictures (NAS) after transplantation of livers from extended criteria donors is currently a major barrier to widespread use of these organs. This review provides an update on the most recent advances in the understanding of the etiology of NAS. These new insights give reason to believe that machine perfusion can reduce the incidence of NAS after transplantation by providing more protective effects on the biliary tree during preservation of the donor liver. An overview is presented regarding the different endpoints that have been used for assessment of biliary injury and function before and after transplantation, emphasizing on methods used during machine perfusion. The wide spectrum of different approaches to machine perfusion is discussed, including the many different combinations of techniques, temperatures and perfusates at varying time points. In addition, the current understanding of the effect of machine perfusion in relation to biliary injury is reviewed. Finally, we explore directions for future research such as the application of (pharmacological) strategies during machine perfusion to further improve preservation. We stress the great potential of machine perfusion to possibly expand the donor pool by reducing the incidence of NAS in extended criteria organs.