High-Dose Methylphenidate and Carboxylesterase 1 Genetic Variability in Patients With Attention-Deficit/Hyperactivity Disorder: A Case Series.

PURPOSE/BACKGROUND: Methylphenidate (MPH) is widely used to reduce symptoms of attention-deficit/hyperactivity disorder. Methylphenidate is metabolized by the carboxylesterase 1 (CES1) enzyme. Some patients need a very high dose of MPH to reach desired clinical effects, without having adverse effects. This may be due to differences in MPH pharmacokinetics (PK), potentially caused by DNA variants in CES1 , the gene encoding the enzyme that metabolizes MPH. Here we describe 3 patients requiring high-dose MPH and investigated the CES1 gene. METHODS/PROCEDURES: The 3 patients were using short-acting MPH in a dose of 180 to 640 mg instead of the maximum advised dose of around 100 mg MPH in the Netherlands. Plasma concentrations of MPH were determined at scheduled time points (day-curve). Methylphenidate plasma concentrations were used for PK analysis using an earlier published 2-compartment PK population model of MPH. Individual data of the 3 patients were compared with simulated population data, when equivalent doses were used. In addition, CES1 was genotyped (number of gene copies and single nucleotide polymorphisms) using real-time polymerase chain reaction. FINDINGS/RESULTS: Pharmacokinetic analysis in all 3 patients showed lower plasma concentrations of MPH in comparison with the population data. The mean absorption time and volume of distribution of the central compartment were equal, but the elimination clearance was higher. However, CES1 genotyping revealed no variations that could explain a higher metabolism of MPH. IMPLICATIONS/CONCLUSIONS: In these 3 cases, we could not demonstrate a correlation between MPH clearance and known genetic variants of the CES1 gene.

Metformin Preconditioning and Postconditioning to Reduce Ischemia Reperfusion Injury in an Isolated Ex Vivo Rat and Porcine Kidney Normothermic Machine Perfusion Model.

Metformin may act renoprotective prior to kidney transplantation by reducing ischemia-reperfusion injury (IRI). This study examined whether metformin preconditioning and postconditioning during ex vivo normothermic machine perfusion (NMP) of rat and porcine kidneys affect IRI. In the rat study, saline or 300 mg/kg metformin was administered orally twice on the day before nephrectomy. After 15 minutes of warm ischemia, kidneys were preserved with static cold storage for 24 hours. Thereafter, 90 minutes of NMP was performed with the addition of saline or metformin (30 or 300 mg/L). In the porcine study, after 30 minutes of warm ischemia, kidneys were preserved for 3 hours with oxygenated hypothermic machine perfusion. Subsequently, increasing doses of metformin were added during 4 hours of NMP. Metformin preconditioning of rat kidneys led to decreased injury perfusate biomarkers and reduced proteinuria. Postconditioning of rat kidneys resulted, dose-dependently, in less tubular cell necrosis and vacuolation. Heat shock protein 70 expression was increased in metformin-treated porcine kidneys. In all studies, creatinine clearance was not affected. In conclusion, both metformin preconditioning and postconditioning can be done safely and improved rat and porcine kidney quality. Because the effects are minor, it is unknown which strategy might result in improved organ quality after transplantation.

Increasing metformin concentrations and its excretion in both rat and porcine ex vivo normothermic kidney perfusion model.

INTRODUCTION: Metformin can accumulate and cause lactic acidosis in patients with renal insufficiency. Metformin is known to inhibit mitochondria, while renal secretion of the drug by proximal tubules indirectly requires energy. We investigated whether addition of metformin before or during ex vivo isolated normothermic machine perfusion (NMP) of porcine and rat kidneys affects its elimination. RESEARCH DESIGN AND METHODS: First, Lewis rats were pretreated with metformin or saline the day before nephrectomy. Subsequently, NMP of the kidney was performed for 90 min. Metformin was added to the perfusion fluid in one of three different concentrations (none, 30 mg/L or 300 mg/L). Second, metformin was added in increasing doses to the perfusion fluid during 4 hours of NMP of porcine kidneys. Metformin concentration was determined in the perfusion fluid and urine by liquid chromatography-tandem mass spectrometry. RESULTS: Metformin clearance was approximately 4-5 times higher than creatinine clearance in both models, underscoring secretion of the drug. Metformin clearance at the end of NMP in rat kidneys perfused with 30 mg/L was lower than in metformin pretreated rats without the addition of metformin during perfusion (both p≤0.05), but kidneys perfused with 300 mg/L trended toward lower metformin clearance (p=0.06). Creatinine clearance was not different between treatment groups. During NMP of porcine kidneys, metformin clearance peaked at 90 min of NMP (18.2±13.7 mL/min/100 g). Thereafter, metformin clearance declined, while creatinine clearance remained stable. This observation can be explained by saturation of metformin transporters with a Michaelis-Menten constant (95% CI) of 23.0 (10.0 to 52.3) mg/L. CONCLUSIONS: Metformin was secreted during NMP of both rat and porcine kidneys. Excretion of metformin decreased under increasing concentrations of metformin, which might be explained by saturation of metformin transporters rather than a self-inhibitory effect. It remains unknown whether a self-inhibitory effect contributes to metformin accumulation in humans with longer exposure times.

Metformin Preconditioning Improves Hepatobiliary Function and Reduces Injury in a Rat Model of Normothermic Machine Perfusion and Orthotopic Transplantation.

BACKGROUND: Preconditioning of donor livers before organ retrieval may improve organ quality after transplantation. We investigated whether preconditioning with metformin reduces preservation injury and improves hepatobiliary function in rat donor livers during ex situ normothermic machine perfusion (NMP) and after orthotopic liver transplantation. METHODS: Lewis rats were administered metformin via oral gavage, after which a donor hepatectomy was performed followed by a standardized cold storage period of 4 hours. Graft assessment was performed using NMP via double perfusion of the hepatic artery and portal vein. In an additional experiment, rat donor livers preconditioned with metformin were stored on ice for 4 hours and transplanted to confirm postoperative liver function and survival. Data were analyzed and compared with sham-fed controls. RESULTS: Graft assessment using NMP confirmed that preconditioning significantly improved ATP production, markers for hepatobiliary function (total bile production, biliary bilirubin, and bicarbonate), and significantly lowered levels of lactate, glucose, and apoptosis. After orthotopic liver transplantation, metformin preconditioning significantly reduced transaminase levels. CONCLUSIONS: Preconditioning with metformin lowers hepatobiliary injury and improves hepatobiliary function in an in situ and ex situ model of rat donor liver transplantation.

Comparing peri-operative complications of paediatric and adult anaesthesia: A retrospective cohort study of 81 267 cases.

BACKGROUND: Comparisons of peri-operative complications associated with paediatric (≤16 years) and adult anaesthesia are poorly available, especially in which cardiac surgery, organ transplantation and neurosurgery are involved. OBJECTIVE: The aim of this study was to evaluate the nature and incidence of peri-operative complications that might be due to anaesthesia and to identify independent risk factors for complications in children and adults, including those undergoing cardiac surgery, organ transplantation and neurosurgery. DESIGN: Retrospective cohort study. SETTING: The study was performed at the University Medical Centre Groningen in the 4 years between 1 January 2010 and the 31 December 2013. MAIN OUTCOME MEASURES: Complications and their severity were graded according to the standard complication score (20 items) of the Dutch Society of Anaesthesia. Univariate and multivariate regression analysis was used to identify independent risk factors for the reported complications. RESULTS: A total of 81 267 anaesthetic cases were included. In the paediatric cohort, there were 410 (2.9%) complications and 1675 (2.5%) in the adults. In both cohorts age, American Society of Anaesthesiologists classification and emergency treatment were independent risk factors for complications. With respect to age, infants less than 1 year were at the highest risk, whereas in the adult cohort, increased age was related to a greater number of complications. The incidences of the specific complications were different between both cohorts. Upper airway obstruction was more frequently observed in paediatric patients (26%), whereas in the adults, complications with the highest incidence concerned conversion of regional-to-general anaesthesia (25%) and hypotension (17%). CONCLUSION: Risk factors for all peri-operative complications were similar for paediatric and adult anaesthesia. However, the incidence of specific complications differed between both age categories.

Normothermic machine perfusion of donor livers without the need for human blood products.

Normothermic machine perfusion (NMP) enables viability assessment of donor livers prior to transplantation. NMP is frequently performed by using human blood products including red blood cells (RBCs) and fresh frozen plasma (FFP). Our aim was to examine the efficacy of a novel machine perfusion solution based on polymerized bovine hemoglobin-based oxygen carrier (HBOC)-201. Twenty-four livers declined for transplantation were transported by using static cold storage. Upon arrival, livers underwent NMP for 6 hours using pressure-controlled portal and arterial perfusion. A total of 12 livers were perfused using a solution based on RBCs and FFPs (historical cohort), 6 livers with HBOC-201 and FFPs, and another 6 livers with HBOC-201 and gelofusine, a gelatin-based colloid solution. Compared with RBC + FFP perfused livers, livers perfused with HBOC-201 had significantly higher hepatic adenosine triphosphate content, cumulative bile production, and portal and arterial flows. Biliary secretion of bicarbonate, bilirubin, bile salts, and phospholipids was similar in all 3 groups. The alanine aminotransferase concentration in perfusate was lower in the HBOC-201-perfused groups. In conclusion, NMP of human donor livers can be performed effectively using HBOC-201 and gelofusine, eliminating the need for human blood products. Perfusing livers with HBOC-201 is at least similar to perfusion with RBCs and FFP. Some of the biomarkers of liver function and injury even suggest a possible superiority of an HBOC-201-based perfusion solution and opens a perspective for further optimization of machine perfusion techniques. Liver Transplantation 24 528-538 2018 AASLD.

Oxygenated hypothermic machine perfusion after static cold storage improves endothelial function of extended criteria donor livers.

BACKGROUND: Lack of oxygen and biomechanical stimulation during static cold storage (SCS) of donor livers compromises endothelial cell function. We investigated the effect of end-ischemic oxygenated hypothermic machine perfusion (HMP) on endothelial cell function of extended criteria donor (ECD) livers. METHODS: Eighteen livers, declined for transplantation, were transported to our center using static cold storage (SCS). After SCS, 6 livers underwent two hours of HMP, and subsequent normothermic machine perfusion (NMP) to assess viability. Twelve control livers underwent NMP immediately after SCS. mRNA expression of transcription factor Krüppel-like-factor 2 (KLF2), endothelial nitric oxide synthase (eNOS), and thrombomodulin (TM) was quantified by RT-PCR. Endothelial cell function and injury were assessed by nitric oxide (NO) production and release of TM into the perfusate. RESULTS: In HMP livers, mRNA expression of KLF2 (p = 0.043), eNOS (p = 0.028), and TM (p = 0.028) increased significantly during NMP. In parallel, NO levels increased during NMP in HMP livers but not in controls. At the end of NMP cumulative TM release was significantly lower HMP livers, compared to controls (p = 0.028). CONCLUSION: A short period of two hours oxygenated HMP restores endothelial cell viability after SCS and subsequent normothermic reoxygenation of ECD livers.

Activation of Fibrinolysis, But Not Coagulation, During End-Ischemic Ex Situ Normothermic Machine Perfusion of Human Donor Livers.

BACKGROUND: Ex situ normothermic machine perfusion (NMP) can be performed after traditional static cold preservation to assess graft function and viability before transplantation. It is unknown whether this results in activation of coagulation and fibrinolysis, as may occur upon graft reperfusion in vivo. METHODS: Twelve donor livers declined for transplantation underwent 6 hours of end-ischemic NMP using a heparinized plasma-based perfusion fluid. Concentration of prothrombin fragment F1 + 2 (marker of coagulation activation), D-dimer, plasmin-antiplasmin complex, tissue plasminogen activator and plasminogen activator inhibitor-1 (markers for fibrinolysis) and alanine aminotransferase (ALT) (marker of ischemia-reperfusion [I/R] injury) were measured in perfusion fluid at regular intervals. Liver biopsies were examined for the presence of fibrin, using light microscopy after Maurits, Scarlet and Blue staining. RESULTS: No significant increase in prothrombin F1 + 2 was noted during NMP. D-dimer and plasmin-antiplasmin complex levels increased soon after start of NMP and D-dimer concentrations correlated significantly with levels of tissue plasminogen activator. In livers displaying good function during NMP, perfusate levels of ALT and D-dimers were low (≤3500 ng/mL), whereas significantly higher D-dimer levels (>3500 ng/mL) were in found in livers with poor graft function. Activation of fibrinolysis correlated significantly with the degree of I/R injury, as reflected by ALT levels. CONCLUSIONS: End-ischemic ex situ NMP results in activation of fibrinolysis, but not of coagulation. Markers of fibrinolysis activation correlate significantly with markers of I/R injury. High concentrations of D-dimer early after start of NMP can be considered a marker of severe I/R injury and a predictor of poor liver graft function.

Strict Selection Alone of Patients Undergoing Liver Transplantation for Hilar Cholangiocarcinoma Is Associated with Improved Survival.

Liver transplantation for hilar cholangiocarcinoma (hCCA) has regained attention since the Mayo Clinic reported their favorable results with the use of a neo-adjuvant chemoradiation protocol. However, debate remains whether the success of the protocol should be attributed to the neo-adjuvant therapy or to the strict selection criteria that are being applied. The aim of this study was to investigate the value of patient selection alone on the outcome of liver transplantation for hCCA. In this retrospective study, patients that were transplanted for hCCA between1990 and 2010 in Europe were identified using the European Liver Transplant Registry (ELTR). Twenty-one centers reported 173 patients (69%) of a total of 249 patients in the ELTR. Twenty-six patients were wrongly coded, resulting in a study group of 147 patients. We identified 28 patients (19%) who met the strict selection criteria of the Mayo Clinic protocol, but had not undergone neo-adjuvant chemoradiation therapy. Five-year survival in this subgroup was 59%, which is comparable to patients with pretreatment pathological confirmed hCCA that were transplanted after completion of the chemoradiation protocol at the Mayo Clinic. In conclusion, although the results should be cautiously interpreted, this study suggests that with strict selection alone, improved survival after transplantation can be achieved, approaching the Mayo Clinic experience.

Intraoperative frozen section analysis of the proximal bile ducts in hilar cholangiocarcinoma is of limited value.

Frozen section analysis (FS) during cancer surgery is widely used to assess resection margins. However, in hilar cholangiocarcinoma (HCCA), FS may be less reliable because of the specific growth characteristics of the tumor. The aim of this study was to determine the accuracy and consequences of intraoperative FS of the proximal bile duct margins in HCCA. Between 1990 and 2014, 67 patients underwent combined extrahepatic bile duct resection and partial liver resection for HCCA with the use of FS. Sensitivity and specificity of FS was 68% and 97%, respectively. Seventeen of 67 patients (25%) displayed a positive bile duct margin at FS. The false-negative rate was 16% (eight patients). Ten patients (15%) with a positive bile duct margin underwent an additional resection in an attempt to achieve negative margins, which succeeded in three patients (4%). However, only one of these three patients did not have concomitant lymph node metastases, which are associated with a poor prognosis by itself. The use of FS of the proximal bile duct is of limited clinical value because of the relatively low sensitivity, high risk of false-negative results, and the low rate of secondary obtained tumor-free resection margins. Supported by the literature, a new approach to the use of FS in HCCA should be adopted, reserving the technique only for cases in which a substantial additional resection is possible.

Normothermic machine perfusion reduces bile duct injury and improves biliary epithelial function in rat donor livers.

Bile duct injury may occur during liver procurement and transplantation, especially in livers from donation after circulatory death (DCD) donors. Normothermic machine perfusion (NMP) has been shown to reduce hepatic injury compared to static cold storage (SCS). However, it is unknown whether NMP provides better preservation of bile ducts. The aim of this study was to determine the impact of NMP on bile duct preservation in both DCD and non-DCD livers. DCD and non-DCD livers obtained from Lewis rats were preserved for 3 hours using either SCS or NMP, followed by 2 hours ex vivo reperfusion. Biomarkers of bile duct injury (gamma-glutamyltransferase and lactate dehydrogenase in bile) were lower in NMP-preserved livers compared to SCS-preserved livers. Biliary bicarbonate concentration, reflecting biliary epithelial function, was 2-fold higher in NMP-preserved livers (P < 0.01). In parallel with this, the pH of the bile was significantly higher in NMP-preserved livers (7.63 ± 0.02 and 7.74 ± 0.05 for non-DCD and DCD livers, respectively) compared with SCS-preserved livers (7.46 ± 0.02 and 7.49 ± 0.04 for non-DCD and DCD livers, respectively). Scanning and transmission electron microscopy of donor extrahepatic bile ducts demonstrated significantly decreased injury of the biliary epithelium of NMP-preserved donor livers (including the loss of lateral interdigitations and mitochondrial injury). Differences between NMP and SCS were most prominent in DCD livers. Compared to conventional SCS, NMP provides superior preservation of bile duct epithelial cell function and morphology, especially in DCD donor livers. By reducing biliary injury, NMP could have an important impact on the utilization of DCD livers and outcome after transplantation. Liver Transplantation 22 994-1005 2016 AASLD.

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.

Diffuse reflectance spectroscopy accurately quantifies various degrees of liver steatosis in murine models of fatty liver disease.

BACKGROUND: A real-time objective evaluation for the extent of liver steatosis during liver transplantation is currently not available. Diffuse reflectance spectroscopy (DRS) rapidly and accurately assesses the extent of steatosis in human livers with mild steatosis. However, it is yet unknown whether DRS accurately quantifies moderate/severe steatosis and is able to distinguish between micro- and macrovesicular steatosis. METHODS: C57BL/6JolaHsd mice were fed wit a choline-deficient L-amino acid-defined diet (CD-AA) or a choline-sufficient L-amino acid-defined control diet (CS-AA) for 3, 8, and 20 weeks. In addition B6.V-Lepob/OlaHsd (ob/ob) mice and their lean controls were studied. A total of 104 DRS measurements were performed in liver tissue ex vivo. The degree of steatosis was quantified from the DRS data and compared with histopathological analysis. RESULTS: When assessed by histology, livers of mice fed with a CD-AA and CS-AA diet displayed macrovesicular steatosis (range 0-74 %), ob/ob mice revealed only microvesicular steatosis (range 75-80 %), and their lean controls showed no steatosis. The quantification of steatosis by DRS correlated well with pathology (correlation of 0.76 in CD-AA/CS-AA fed mice and a correlation of 0.75 in ob/ob mice). DRS spectra did not distinguish between micro- and macrovesicular steatosis. In samples from CD-AA/CS-AA fed mice, the DRS was able to distinguish between mild and moderate/severe steatosis with a sensitivity and specificity of 86 and 81 %, respectively. CONCLUSION: DRS can quantify steatosis with good agreement to histopathological analysis. DRS may be useful for real-time objective evaluation of liver steatosis during liver transplantation, especially to differentiate between mild and moderate/severe steatosis.

Ex Situ Normothermic Machine Perfusion of Donor Livers.

In contrast to conventional static cold preservation (0-4 °C), ex situ machine perfusion may provide better preservation of donor livers. Continuous perfusion of organs provides the opportunity to improve organ quality and allows ex situ viability assessment of donor livers prior to transplantation. This video article provides a step by step protocol for ex situ normothermic machine perfusion (37 °C) of human donor livers using a device that provides a pressure and temperature controlled pulsatile perfusion of the hepatic artery and continuous perfusion of the portal vein. The perfusion fluid is oxygenated by two hollow fiber membrane oxygenators and the temperature can be regulated between 10 °C and 37 °C. During perfusion, the metabolic activity of the liver as well as the degree of injury can be assessed by biochemical analysis of samples taken from the perfusion fluid. Machine perfusion is a very promising tool to increase the number of livers that are suitable for transplantation.

End-ischemic machine perfusion reduces bile duct injury in donation after circulatory death rat donor livers independent of the machine perfusion temperature.

A short period of oxygenated machine perfusion (MP) after static cold storage (SCS) may reduce biliary injury in donation after cardiac death (DCD) donor livers. However, the ideal perfusion temperature for protection of the bile ducts is unknown. In this study, the optimal perfusion temperature for protection of the bile ducts was assessed. DCD rat livers were preserved by SCS for 6 hours. Thereafter, 1 hour of oxygenated MP was performed using either hypothermic machine perfusion, subnormothermic machine perfusion, or with controlled oxygenated rewarming (COR) conditions. Subsequently, graft and bile duct viability were assessed during 2 hours of normothermic ex situ reperfusion. In the MP study groups, lower levels of transaminases, lactate dehydrogenase (LDH), and thiobarbituric acid reactive substances were measured compared to SCS. In parallel, mitochondrial oxygen consumption and adenosine triphosphate (ATP) production were significantly higher in the MP groups. Biomarkers of biliary function, including bile production, biliary bicarbonate concentration, and pH, were significantly higher in the MP groups, whereas biomarkers of biliary epithelial injury (biliary gamma-glutamyltransferase [GGT] and LDH), were significantly lower in MP preserved livers. Histological analysis revealed less injury of large bile duct epithelium in the MP groups compared to SCS. In conclusion, compared to SCS, end-ischemic oxygenated MP of DCD livers provides better preservation of biliary epithelial function and morphology, independent of the temperature at which MP is performed. End-ischemic oxygenated MP could reduce biliary injury after DCD liver transplantation.

Elderly donor liver grafts are not associated with a higher incidence of biliary complications after liver transplantation: results of a national multicenter study.

BACKGROUND: Liver transplantation with livers grafts from elderly donors has been associated with a higher risk of biliary complications. The aim of this study was to examine whether our national protocol could contribute to a lower incidence of biliary complications. METHODS: All adult recipients in the Netherlands transplanted with a liver from an elderly donor (≥ 65 yrs; n = 68) in the period January 2000-July 2011 were matched with recipients of a liver from a donor <65 yr (n = 136). Outcome parameters were 90-d, one-yr, and three-yr patient/graft survival rates, biliary complications (non-anastomotic stricture, anastomotic stricture, biliary leakage, and post-transplant cholangitis), and postoperative hepatic ischemic injury serum markers (AST/ALT). RESULTS: The median cold ischemia time (CIT) was 7:25 (h:min) in the group recipients of an elderly donor liver graft. Ninety-day, one-yr, and three-yr patient/graft survival rates were similar between the group with an elderly donor liver and their younger controls. Moreover, no differences were found in the incidence of biliary complications and postoperative levels of AST/ALT between the two groups. CONCLUSION: Transplantation of livers from elderly donors (≥ 65 yr) is not associated with a higher incidence of biliary complications, in a national policy wherein the CIT is kept short.

Diffuse reflectance spectroscopy: toward real-time quantification of steatosis in liver.

Assessment of fatty liver grafts during orthotopic liver transplantation is a challenge due to the lack of real-time analysis options during surgery. Diffuse reflectance spectroscopy (DRS) could be a new diagnostic tool to quickly assess steatosis. Eight hundred and seventy-eight optical measurements were performed in vivo in 17 patients in liver tissue during surgery and ex vivo on liver resection specimens from 41 patients. Liver steatosis was quantified from the collected optical spectra and compared with the histology analysis from the measurement location by three independent pathologists. Twenty two patients were diagnosed with <5% steatosis, 15 patients had mild steatosis, and four had moderate steatosis. Severe steatosis was not identified. Intraclass correlation between the pathologists analysis was 0.949. A correlation of 0.854 was found between the histology and DRS analyses of liver steatosis ex vivo. For the same liver tissue, a correlation of 0.925 was demonstrated between in vivo and ex vivo DRS analysis for steatosis quantification. DRS can quantify steatosis in liver tissue both in vivo and ex vivo with good agreement compared to histopathology analysis. This analysis can be performed real time and may therefore be useful for fast objective assessment of liver steatosis in liver surgery.

Similar outcome after transplantation of moderate macrovesicular steatotic and nonsteatotic livers when the cold ischemia time is kept very short.

BACKGROUND: Livers with moderate (30-60%) macrovesicular steatosis have been associated with poor outcome after transplantation. Aim of this study was to examine the outcome after transplantation of livers with moderate macrovesicular steatosis when the cold ischemia time (CIT) is kept very short. METHODS: Postoperative outcome of 19 recipients of a moderate steatotic liver were compared with a matched control group of 95 recipients of a nonsteatotic liver graft (1:5 ratio). We studied graft/patient survival rates, incidences of primary nonfunction, postoperative complications (classified according to the Clavien-Dindo classification), first-week postoperative hepatic injury serum markers (AST/ALT), and liver function tests (PT time/bilirubin/lactate). In addition, we studied reversal of graft steatosis in follow-up biopsies. RESULTS: Median CIT in livers with moderate steatosis and in controls was below 8 h in both groups. Although short- and long-term patient/graft survival rates and results of liver function tests were similar, serum markers of hepatic injury and postoperative complications (especially grade IVa) were significantly higher in recipients of a moderate steatotic liver. Reversal of steatosis was seen in 9 of the 11 (82%) recipients with follow-up liver biopsies. CONCLUSION: Despite the association with severe postoperative complications, moderate macrovesicular steatotic livers can be used successfully for transplantation if the CIT is kept very short.

Biliary complications after orthotopic liver transplantation.

PURPOSE OF REVIEW: The incidence, pathogenesis and management of the most common biliary complications are summarized, with an emphasis on nonanastomotic biliary strictures (NAS) and potential strategies to prevent NAS after liver transplantation. RECENT FINDINGS: NAS have variable presentations in time and localization, suggesting various underlying pathogeneses. Early-onset NAS (presentation within 1 year) have shown to be largely related to ischemia-induced bile duct injury, whereas late-onset NAS [>1 year after orthotopic liver transplantation (OLT)] have more immune-mediated causes. Cytotoxic hydrophobic bile salts and impaired biliary HCO3 secretion may also play a role in the occurrence of NAS. Recently, insufficient biliary epithelial regeneration capacity after transplantation has also been suggested to play a major role in the pathogenesis of NAS. A potential strategy to prevent NAS has been proposed to be preservation by machine perfusion instead of classical static cold storage. Although machine perfusion has been shown to be a better preservation method for the liver parenchyma, efficacy in preventing ischemic injury of the biliary epithelium is largely unknown. SUMMARY: The potential advantages of machine perfusion are very promising as it may provide better protection of the vulnerable bile ducts against ischemia-reperfusion injury. Clinical trials will be needed to demonstrate the impact of machine perfusion in reducing the incidence of biliary complications, especially NAS, after OLT.

Injury to peribiliary glands and vascular plexus before liver transplantation predicts formation of non-anastomotic biliary strictures.

BACKGROUND & AIMS: The peribiliary glands of large bile ducts have been identified as a niche of progenitor cells that contribute to regeneration of biliary epithelium after injury. We aimed to determine whether injury to the peribiliary glands of donor livers is a risk factor for development of non-anastomotic biliary strictures (NAS) after liver transplantation. METHODS: In 128 liver transplant procedures, biopsies were taken from the donor bile duct and injury was assessed using an established histological grading system. Histological severity of injury was subsequently compared in liver grafts that later developed biliary structures vs. uncomplicated liver grafts. RESULTS: Luminal biliary epithelial loss >50% was observed in 91.8% of the grafts before transplantation, yet NAS occurred in only 16.4%. Periluminal peribiliary glands were more severely injured than deep peribiliary glands located near the fibromuscular layer (>50% loss in 56.9% vs. 17.5%, respectively; p<0.001). Injury of deep peribiliary glands was more prevalent and more severe in livers that later developed NAS, compared to grafts without NAS (>50% loss in 50.0% vs. 9.8%, respectively; p=0.004). In parallel, injury of the peribiliary vascular plexus was more severe in livers that developed NAS, compared to grafts without NAS (>50% vascular changes in 57.1% vs. 20.3%; p=0.006). CONCLUSION: Injury of peribiliary glands and vascular plexus before transplantation is strongly associated with the occurrence of biliary strictures after transplantation. This suggests that insufficient regeneration due to loss of peribiliary glands or impaired blood supply may explain the development of biliary strictures.