Risk factors of severe ischemic biliary complications after liver transplantation

Exosomes derived from TGF-β1-pretreated mesenchymal stem cells alleviate biliary ischemia-reperfusion injury through Jagged1/Notch1/SOX9 pathway

BACKGROUND

This study aimed to evaluate the efficacy of exosomes (EXO) derived from TGF-β1-pretreated mesenchymal stem cells (MSCs) on biliary ischemia reperfusion injury (IRI) and further reveal the possible mechanisms.

METHODS

Bone marrow-derived MSCs were treated with exogenous TGF-β1, Jagged1/Notch1/SOX9 pathway inhibitor LY450139, or their combination. Then, EXO were isolated from the culture supernatants and further characterized. After establishing IRI model of biliary epithelial cells (EpiCs), EXO derived from differently-treated MSCs were applied to detect their protective effects on EpiCs, and LY450139 was applied in EpiCs to detect the possible mechanisms after treatment with MSCs-EXO. EXO derived from differently-treated MSCs were further injected into the hepatic artery immediately after establishment of intrahepatic biliary IRI for animal studies.

RESULTS

Pretreatment with TGF-β1 significantly enhanced MSCs-EXO production and elevated the levels of massive miRNAs associated with anti-apoptosis and tissue repair, which were evidently decreased after TGF-β1 plus LY450139 cotreatment. Notable improvement was observed in EpiCs after MSCs-EXO treatment, evidenced by reduced cellular apoptosis, increased cellular proliferation and declined oxidative stress, which were more evident in EpiCs that were treated with EXO derived from TGF-β1-pretreated MSCs. However, application of EXO derived from TGF-β1 plus LY450139-cotreated MSCs reversely enhanced cellular apoptosis, decreased cellular proliferation and anti-oxidants production. Interestingly, LY450139 application in EpiCs after treatment with MSCs-EXO also reversed the declined cellular apoptosis and enhanced oxidative stress induced by TGF-β1 pretreatment. In animal studies, administration of EXO derived from TGF-β1-pretreated MSCs more effectively attenuated biliary IRI through reducing oxidative stress, apoptosis, inflammation and enhancing the expression levels of TGF-β1 and Jagged1/Notch1/SOX9 pathway-related markers, which were reversed after administration of EXO derived from TGF-β1 plus LY450139-cotreated MSCs.

CONCLUSION

Our results provided a vital insight that TGF-β1 pretreatment endowed MSCs-EXO with stronger protective effects to improve biliary IRI via Jagged1/Notch1/SOX9 pathway.

Impact of different ischemia times on biliary stricture after living donor liver transplantation with biliary atresia

Biliary atresia (BA) is the most common indication for pediatric liver transplantation, and biliary stricture (BS) remains an Achilles' heel for pediatric living donor liver transplantation (LDLT). We investigated the impact of different ischemia times on BS after LDLT in patients with BA. We retrospectively analyzed patients (<18 y) with BA who underwent LDLT between January 2016 and December 2020. Cases with hepatic artery thrombosis, bile leakage, early BS (<2 wk), and early death (<3 mo) were excluded. In all, 572 cases were included. A total of 26 cases (4.55%, 26/572) developed BS: 25 patients with anastomotic stricture and 1 patient with anastomotic stricture combined with left hepatic duct stricture. In addition, the time to diagnosis of BS ranged from 1.8 to 53.0 months (mean, 13.0 mo and median, 8.2 mo) after transplantation. A multivariate logistic regression analysis showed that arterial ischemia time (AIT), per 10 minutes (OR=1.222, 95% CI: 1.007-1.438, p =0.04) was the only independent risk factor for the development of BS after LDLT in patients with BA. What is more, the 5-year cumulative risk of BS between the AIT ≥40 minutes and AIT <40 minutes groups was 2.79% versus 10.57%. AIT was the only independent risk factor for the development of BS after LDLT with BA, and AIT ≥40 minutes would increase the 5-year cumulative risk of BS in our study. A shorter AIT, especially AIT <40 minutes, should be kept to decrease BS.

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.

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.

Biliary complications after liver transplantation

Biliary complications (BCs) remain one of the most outstanding factors influencing long-term results after orthotopic liver transplantation. The authors carried out a systematic overview of 1720 papers since 2008, and focused on 45 relevant ones. Among 14,411 transplanted patients the incidence of BCs was 23%. Biliary leakage occurred in 8.5%, biliary stricture in 14.7%, mortality rate was 1-3%.

RISK FACTORS

preoperative sodium level; p = 0.037, model of end-stage liver disease score >25; p = 0.048, primary sclerosing cholangitis; p = 0.001, malignancy; p = 0.026, donor age >60, macrovesicular graft steatosis; p = 0.001, duct-to-duct anastomosis; p = 0.004, long anhepatic phase; p = 0.04, cold ischemic time >12 h; p = 0.043, use of T-tube; p = 0.032, insufficient flush of bile ducts; p = 0.001, acute rejection; p = 0.003, cytomegalovirus infection; p = 0.004 and hepatic artery thrombosis; p = 0.001. The management was surgical in case of biliary leakage, and interventional radiology or endoscopic retrograde cholangiopancreatography in case of biliary stricture. Mapping of miRNA profile is a new field of research. Nemes-Doros score is a useful tool in the estimation of hepatic artery thrombosis. Management of BCs requires a multidisciplinary expert team.

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.

Impact of recombinant globular adiponectin on early warm ischemia-reperfusion injury in rat bile duct after liver transplantation

Adiponectin (APN) is an adipocyte protein with anti-diabetic properties, which has been recently revealed to have anti-inflammatory activity in organ ischemia- reperfusion injury (IRI). However, little is known about its function in bile duct IRI after liver transplantation. Therefore, we investigated whether APN affects early warm IRI in rat bile duct using a liver autologous transplantation model. In our study, rats were randomly divided into three experimental groups: a sham group, a IRI group, and a APN group. The serum enzyme levels and BDISS scores of bile duct histology associated with bile duct injury, decreased after administration of APN. Subsequently, the expression of proinflammatory cytokines, such as tumor necrosis factor(TNF-α),.interleukin-6(IL-6) and myeloperoxidase (MPO) decreased. Furthermore, pretreatment with APN suppressed the activation of nuclear factor-kappa B (NF-κB) (p65), a transcription factor involved in inflammatory reactions, compared to other two groups. Administration of APN also downregulated the expression of Fas protein and attenuated caspase-3 activity to decrease bile duct apoptosis. Our results illustrate that APN protects the rat bile duct against early warm IRI by suppressing the inflammatory response and hepatocyte apoptosis, and NF-κB (p65) plays an important role in this process.

Regulation of molecular pathways in ischemia-reperfusion injury after liver transplantation

BACKGROUND

Ischemia-reperfusion (I/R) injury is a multifactorial phenomenon that occurs during the transplant event and frequently compromises early graft function after liver transplantation (LT). Current comprehension of molecular mechanisms and regulation processes of I/R injury lacks clarity. MicroRNA (miRNA) regulation results critical in several biological processes.

METHODS

This study evaluated gene expression and miRNA expression profiles using microarrays in 34 graft biopsies collected at preimplantation (L1) and at 90 min postreperfusion (L2) from consecutives deceased-donor LT recipients. miRNA profiles were first analyzed. Data integration analysis (gene expression/miRNA expression) aimed to identify potential target genes for each identified miRNA from the L1/L2 differential gene expression profile.

RESULTS

Pairwise comparison analyses identified 40 miRNAs and 3168 significantly differentially expressed genes at postreperfusion time compared with preimplantation time. Pathway analysis of miRNAs associated these profiles with antiapoptosis, inhibition of cellular proliferation, and proinflammatory processes. Target analysis identified an miRNA-associated molecular profile of 2172 genes involved in cellular growth and proliferation modulation by cell cycle regulation, cell death and survival, and proinflammatory and anti-inflammatory processes. miRNA-independent genes involved proinflammatory molecules.

CONCLUSION

We identified a miRNA profile involved in posttranscriptional regulatory mechanisms in I/R injury post-LT. A better understanding of these molecular processes involved in I/R may contribute to develop new strategies to minimize graft injury.

Protective effect of gadolinium chloride on early warm ischemia/reperfusion injury in rat bile duct during liver transplantation

Background

Activation of Kupffer cell (KC) is acknowledged as a key event in the initiation and perpetuation of bile duct warm ischemia/reperfusion injury. The inhibitory effect of gadolinium chloride (GdCl₃) on KC activation shows potential as a protective intervention in liver injury, but there is less research with regard to bile duct injury.

Methods

Sixty-five male Sprague-Dawley rats (200–250 g) were randomly divided into three experimental groups: a sham group (n = 15), a control group (n = 25), and a GdCl₃ group (n = 25). Specimen was collected at 0.5, 2, 6, 12 and 24 h after operation. Alanine aminotransferase (ALT), alkaline phosphatase (ALP) and total bilirubin (TBIL) of serum were measured. Tumor necrosis factor-α (TNF-α), Capase-3 activity and soluble Fas (sFas) were detected. The pathologic changes of bile duct were observed. Immunochemistry for bile duct Fas was performed. Apoptosis of bile duct cells was evaluated by the terminal UDP nick end labeling assay.

Results

GdCl₃ significantly decreased the levels of ALT, ALP and TBIL at 2, 6, 12, and 24 h, and increased serum sFas at 2, 6 and 12 h (P<0.05). TNF-α was lower in the GdCl₃ group than in the control group at 2, 6, 12 and 24 h (P<0.05). Preadministration of GdCl₃ significantly reduced the Caspase-3 activity and bile duct cell apoptosis at 2, 6, 12 and 24 h. After operation for 2, 6 and 12 h, the expression of Fas protein was lower in the GdCl₃ group than in the control group (P<0.05).

Conclusions

GdCl₃ plays an important role in suppressing bile duct cell apoptosis, including decreasing ALT, ALP, TBIL and TNF-α; suppressing Fas-FasL-Caspase signal transduction during transplantation.

Resource implications of expanding the use of donation after circulatory determination of death in liver transplantation

In the United Kingdom, liver transplantation using donation after circulatory determination of death (DCDD) organs has increased steadily over the last few years and now accounts for 20% of UK transplant activity. The procurement of DCDD livers is actively promoted as a means of increasing the donor pool and bridging the evolving disparity between the wait-list length and the number of transplants performed. The objective of this retrospective study of a cohort of patients who were matched for age, liver disease etiology, and Model for End-Stage Liver Disease score was to determine whether differences in perioperative costs and resource utilization are associated with the use of such organs. Our results showed an increased prevalence of reperfusion syndrome in the DCDD cohort (P < 0.001), a prolonged heparin effect (P = 0.01), a greater incidence of hyperfibrinolysis (P = 0.002), longer periods of postoperative ventilator use (P = 0.03) and vasopressor support (P = 0.002), and a prolonged length of stay in the intensive therapy unit (ITU; P = 0.02). The peak posttransplant aspartate aminotransferase level was higher in the DCDD group (P = 0.007), and there was significantly more graft failure at 12 months (P = 0.03). In conclusion, we have demonstrated different perioperative and early postoperative courses for DCDD and donation after brain death (DBD) liver transplants. The overall quality of DCDD grafts is poorer; as a result, the length of the ITU stay and the need for multiorgan support are increased, and this has significant financial and resource implications. We believe that these implications require a careful real-life consideration of benefits. It is essential for DCDD not to be seen as a like-for-like alternative to DBD and for every effort to be continued to be made to increase the number of donations from brain-dead patients as a first resort.