Publications by authors named "Greg Nowak"

42 Publications

Liver Transplantation for Acute Intermittent Porphyria.

Liver Transpl 2020 Dec 1. Epub 2020 Dec 1.

Hepatology Division, Department of Upper GI Diseases, Porphyria Centre Sweden, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden.

Recurrent attacks of acute intermittent porphyria (AIP) result in poor quality of life and significant risks of morbidity and mortality. Liver transplantation (LT) offers a cure, but published data on outcomes after LT are limited. We assessed the pretransplant characteristics, complications, and outcomes for patients with AIP who received a transplant. Data were collected retrospectively from the European Liver Transplant Registry and from questionnaires sent to identified transplant and porphyria centers. We studied 38 patients who received transplants in 12 countries from 2002 to 2019. Median age at LT was 37 years (range, 18-58), and 34 (89%) of the patients were women. A total of 9 patients died during follow-up, and 2 patients were retransplanted. The 1-year and 5-year overall survival rates were 92% and 82%, which are comparable with other metabolic diseases transplanted during the same period. Advanced pretransplant neurological impairment was associated with increased mortality. The 5-year survival rate was 94% among 19 patients with moderate or no neuropathy at LT and 83% among 10 patients with severe neuropathy (P = 0.04). Pretransplant renal impairment was common. A total of 19 (51%) patients had a GFR < 60 mL/minute. Although few patients improved their renal function after LT, neurological impairments improved, and no worsening of neurological symptoms was recorded. No patient had AIP attacks after LT, except for a patient who received an auxiliary graft. LT is a curative treatment option for patients with recurrent attacks of AIP. Severe neuropathy and impaired renal function are common and increase the risk for poor outcomes. If other treatment options fail, an evaluation for LT should be performed early.
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http://dx.doi.org/10.1002/lt.25959DOI Listing
December 2020

The role of the comprehensive complication index for the prediction of survival after liver transplantation.

Updates Surg 2021 Feb 6;73(1):209-221. Epub 2020 Sep 6.

Starzl Unit of Abdominal Transplantation, Pôle de Chirurgie Expérimentale et Transplantation, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium.

In the last years, several scoring systems based on pre- and post-transplant parameters have been developed to predict early post-LT graft function. However, some of them showed poor diagnostic abilities. This study aims to evaluate the role of the comprehensive complication index (CCI) as a useful scoring system for accurately predicting 90-day and 1-year graft loss after liver transplantation. A training set (n = 1262) and a validation set (n = 520) were obtained. The study was registered at https://www.ClinicalTrials.gov (ID: NCT03723317). CCI exhibited the best diagnostic performance for 90 days in the training (AUC = 0.94; p < 0.001) and Validation Sets (AUC = 0.77; p < 0.001) when compared to the BAR, D-MELD, MELD, and EAD scores. The cut-off value of 47.3 (third quartile) showed a diagnostic odds ratio of 48.3 and 7.0 in the two sets, respectively. As for 1-year graft loss, CCI showed good performances in the training (AUC = 0.88; p < 0.001) and validation sets (AUC = 0.75; p < 0.001). The threshold of 47.3 showed a diagnostic odds ratio of 21.0 and 5.4 in the two sets, respectively. All the other tested scores always showed AUCs < 0.70 in both the sets. CCI showed a good stratification ability in terms of graft loss rates in both the sets (log-rank p < 0.001). In the patients exceeding the CCI ninth decile, 1-year graft survival rates were only 0.7% and 23.1% in training and validation sets, respectively. CCI shows a very good diagnostic power for 90-day and 1-year graft loss in different sets of patients, indicating better accuracy with respect to other pre- and post-LT scores.Clinical Trial Notification: NCT03723317.
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http://dx.doi.org/10.1007/s13304-020-00878-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889667PMC
February 2021

Energy expenditure early after liver transplantation: Better measured than predicted.

Nutrition 2020 Nov - Dec;79-80:110817. Epub 2020 Mar 20.

Department of Gastroenterology and Hepatology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.

Objective: There is no consensus on how to estimate energy requirements after liver transplantation (LT). The aim of this study was to compare measured resting energy expenditure (REE) with predictive equations and fixed factors, and evaluate whether clinical variables were associated with REE.

Methods: During the period of 2011 through 2018, REE measured with indirect calorimetry and predicted by the Harris and Benedict (HB) equation was compared in patients during the first 30 postoperative days after LT. The fixed factors 25 kcal/kg, 30 kcal/kg, or 35 kcal/kg were used to calculate energy requirements. The accuracy of HB and fixed factors were evaluated with a Bland-Altman analysis and Lin's concordance correlation coefficient. The associations of pre- and postoperative clinical variables with REE were evaluated in a multivariate regression analysis.

Results: A total of 143 patients were evaluated and had indirect calorimetry performed on postoperative day 6 (interquartile range: 3) in median. The mean measured REE was 1950 ± 461 kcal (range, 720-3309 kcal) or 24.5 ± 6.1 kcal/kg body weight. Large limits of agreements were observed in the Bland-Altman analyses for both HB and fixed factors. HB was closer than fixed factors with a positive concordance (concordance correlation: 0.350; 95% confidence interval, 0.248-0.445) and Pearsons r = 0.261. Measured REE was significantly associated (P < 0.05) with age, sex, Model for End-Stage Liver Disease score before LT, surgery time, and graft cold ischemia time according to the multiple regression analysis.

Conclusions: The low accuracy of HB and fixed factors suggests risks of both under- and overfeeding of individual patients if energy requirement is only based on calculation. REE measurement is recommended after LT to secure accurate and safe nutritional therapy.
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http://dx.doi.org/10.1016/j.nut.2020.110817DOI Listing
March 2020

Intrahepatic Microdialysis for Monitoring of Metabolic Markers to Detect Rejection Early After Liver Transplantation.

Transplant Proc 2021 Jan-Feb;53(1):130-135. Epub 2020 Jul 4.

Division of Transplant Surgery, Department for Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.

Objectives: The clinical and biochemical manifestations of acute rejection after liver transplantation are nonspecific, and a liver biopsy is often needed to verify the diagnosis. This may delay treatment. The aim of this study was to evaluate whether monitoring of intrahepatic glucose, lactate, pyruvate, and glycerol by microdialysis can be used to predict rejection early after liver transplantation.

Methods: Seventy-one patients undergoing liver transplantation were included in the study. The patients were monitored using microdialysis for up to 6 days postoperatively. Patients who developed acute rejection within 1 month were identified according to standard protocol. Area under the curve (AUC) was calculated for 12-hour intervals for glucose, lactate, pyruvate, glycerol, and lactate/pyruvate ratio. Patients with and without rejection were compared with respect to these parameters, as well as standard liver blood investigations and time-zero biopsies.

Results: The lactate/pyruvate ratio was higher at 0 to 12 hours in the group with rejection as compared to the group without rejection. Glucose was lower in the group with rejection at 24 to 48 hours. Also, the intrahepatic lactate levels at 48 to 72 hours and pyruvate levels at 60 to 72 hours after liver transplantation, were higher in the rejection group. The lactate/pyruvate ratio at 0 to 12 hours and lactate at 60 to 72 hours were two independent risk factors for rejection within the first month after liver transplantation. No significant differences in glycerol levels could be detected between the two patient groups.

Conclusions: Microdialysis monitoring following liver transplantation may be useful in the detection of the metabolic events that precede rejection. The metabolic patterns detected by microdialysis early after transplantation indicate a possible relation between primary ischemia-reperfusion injury and the development of rejection. Identifying these patterns may help to identify patients at risk for the development of acute rejection and may help select those who may benefit from higher dose of immunosuppression early after liver transplantation.
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http://dx.doi.org/10.1016/j.transproceed.2020.02.157DOI Listing
July 2020

Systemic modified messenger RNA for replacement therapy in alpha 1-antitrypsin deficiency.

Sci Rep 2020 04 27;10(1):7052. Epub 2020 Apr 27.

Division of Transplantation Surgery, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden.

Alpha 1-antitrypsin (AAT) deficiency arises from an inherited mutation in the SERPINA1 gene. The disease causes damage in the liver where the majority of the AAT protein is produced. Lack of functioning circulating AAT protein also causes uninhibited elastolytic activity in the lungs leading to AAT deficiency-related emphysema. The only therapy apart from liver transplantation is augmentation with human AAT protein pooled from sera, which is only reserved for patients with advanced lung disease caused by severe AAT deficiency. We tested modified mRNA encoding human AAT in primary human hepatocytes in culture, including hepatocytes from AAT deficient patients. Both expression and functional activity were investigated. Secreted AAT protein increased from 1,14 to 3,43 µg/ml in media from primary human hepatocytes following mRNA treatment as investigated by ELISA and western blot. The translated protein showed activity and protease inhibitory function as measured by elastase activity assay. Also, mRNA formulation in lipid nanoparticles was assessed for systemic delivery in both wild type mice and the NSG-PiZ transgenic mouse model of AAT deficiency. Systemic intravenous delivery of modified mRNA led to hepatic uptake and translation into a functioning protein in mice. These data support the use of systemic mRNA therapy as a potential treatment for AAT deficiency.
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http://dx.doi.org/10.1038/s41598-020-64017-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7184591PMC
April 2020

Evaluation of Intrahepatic Lactate/Pyruvate Ratio As a Marker for Ischemic Complications Early After Liver Transplantation-A Clinical Study.

Transplant Direct 2019 Dec 15;5(12):e505. Epub 2019 Nov 15.

Department for Clinical Science, Intervention and Technology (CLINTEC), Division of Transplant Surgery and Division of Surgery, Karolinska Institute, Karolinska University Hospital, Huddinge, Stockholm, Sweden.

Background: Lactate/pyruvate ratio has been introduced as a sensitive marker for ischemia in the transplanted liver. In the present study, we aimed to evaluate lactate/pyruvate ratio measured in the liver by microdialysis as a marker for ischemic complications early after liver transplantation.

Methods: Forty-five patients undergoing liver transplantation were included in the study. A microdialysis catheter was placed in the liver graft directly following liver transplantation and the metabolites lactate and pyruvate measured for up to 6 days and the lactate/pyruvate ratio calculated. The association between increased intrahepatic lactate/pyruvate ratio and ischemic complications was studied.

Results: One of 45 patients developed hepatic arterial thrombosis. Forty-four events with increased lactate/pyruvate ratio were identified in 24 patients. In none of the 24 patients that had a raised lactate/pyruvate ratio could we detect occurrence of any ischemic complication. In the patient that did have hepatic arterial thrombosis, the lactate/pyruvate ratio did not show a significant prolonged rise.

Conclusions: An increase in the intrahepatic lactate/pyruvate ratio is not necessarily indicative of ischemic complications and is thus not a reliable marker for monitoring of clinically significant ischemia in the liver early after transplantation.
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http://dx.doi.org/10.1097/TXD.0000000000000952DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004593PMC
December 2019

Transfer of Hemolysis, Elevated Liver Enzymes, and Low Platelets Syndrome by a Liver Graft From a Pregnant Female Donor to a Male Recipient: A Case Report.

Transplant Proc 2020 Mar 5;52(2):644-646. Epub 2020 Feb 5.

Division of Transplantation Surgery, Karolinska University Hospital Huddinge, Stockholm, Sweden; Department of Clinical Science, Intervention, and Technology (CLINTEC), Karolinska Institute, Stockholm, Sweden.

Eclampsia with hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome is a rare complication of pregnancy. HELLP syndrome may occur up to a week postpartum in women with eclampsia. CASE REPORT: We report a case of liver transplantation with the organ procured from a pregnant (gestation week 28) female donor who suffered brain death after cerebellar hemorrhage owing to eclampsia. Liver function tests were normal at the time of liver procurement. The liver graft was matched to a 62-year-old man with primary sclerosing cholangitis. On day 7 after an uneventful transplantation, the recipient presented with increased aminotransferases and severe thrombocytopenia. The recipient also developed hypertension and hyperthermia and a clinical picture of HELLP syndrome. The patient underwent emergency liver retransplantation on day 12 after the first transplantation. Intraoperatively, massive necrosis of the liver graft with diffuse subcapsular hematomas was seen. CONCLUSIONS: It appears that in our case, HELLP syndrome was transferred to and occurred in a male recipient. Eclampsia in the donor without overt HELLP syndrome may persist and be transferred by liver graft, developing into HELLP syndrome even in a male recipient. Therefore, liver grafts from female donors with eclampsia should be used with caution. Emergency retransplantation may be necessary.
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http://dx.doi.org/10.1016/j.transproceed.2019.10.037DOI Listing
March 2020

Impact of Hepatic Artery Variations and Reconstructions on the Outcome of Orthotopic Liver Transplantation.

World J Surg 2020 06;44(6):1954-1965

Division of Transplantation Surgery, CLINTEC, Karolinska University Hospital, Huddinge, 141 86, Stockholm, Sweden.

Background: Donor variational arteries often require complex reconstruction.

Methods: We analysed the incidence of different variations, types of arterial reconstructions and their impact on post-operative results from 409 patients undergoing liver transplantation at Karolinska Institute between 2007 and 2015.

Results: A total of 292 (71.4%) liver grafts had a standard hepatic artery (SHA), and 117 (28.6%) showed hepatic artery variants (HAV). 58% of HAV needed reconstruction. The main variations were variant left hepatic artery (45.3%) from the gastric artery; variant right hepatic artery (38.5%); and a triple combination of variant right and left hepatic artery and the proper hepatic artery from the common hepatic artery (12.8%); other 3.4%. Patients/graft survival and arterial complications were not different between SHA and HAV. Incidence of biliary stricture was numerically higher in left hepatic artery variants (p = 0.058) and in variants where no arterial reconstruction was performed (p = 0.001). Operation and arterial warm ischaemia time were longer in the HAV group. The need for intraoperative re-reconstruction was higher in the HAV group (p = 0.04). Intraoperative bleeding was larger after back-table reconstruction than with intraoperative reconstruction (p = 0.04).

Conclusion: No overall differences were found between the HAV and the SHA groups. Occurrence of a variant left hepatic artery and HAV with no reconstruction seems to increase the risk of biliary strictures.
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http://dx.doi.org/10.1007/s00268-020-05406-4DOI Listing
June 2020

Association of post-reperfusion syndrome and ischemia-reperfusion injury with acute kidney injury after liver transplantation.

Acta Anaesthesiol Scand 2020 07 20;64(6):742-750. Epub 2020 Feb 20.

Department of Clinical Science, Intervention and Technology, Division of Transplantation Surgery, Karolinska Institutet, Huddinge, Sweden.

Background: Acute kidney injury (AKI) is frequently observed after orthotopic liver transplantation (OLT) even in patients with previously normal renal function. In this study, we investigated the impact of factors such graft steatosis, post-reperfusion syndrome (PRS), and hepatic ischemia reperfusion injury (HIRI) on the development of AKI after OLT in adult patients.

Methods: We retrospectively examined consecutive adult patients who underwent OLT at our institution between July 2011 and June 2017. AKI was diagnosed based on the criteria proposed by the International Kidney Disease Improving Global Outcomes (KDIGO) workgroup. Peak aspartate aminotransferase (AST) level within 72 hours after OLT was used as a surrogate marker for HIRI. Graft steatosis was diagnosed by histopathological examination using specimens biopsied intraoperatively at the end of transplantation procedure and categorized as <10%, 10%-20%, 20%-30%, and ≥30% of hepatic steatosis.

Results: Out of 386 patients, 141 (37%) developed AKI (KDIGO stage 1:71 patients; stage 2:29 patients; stage 3:41 patients). Multivariable logistic regression analysis revealed that cold ischemic time (P = .012) and HIRI (P = .007) were independent risk factors for post-OLT AKI. Multivariable analysis also revealed that graft steatosis was associated with HIRI but not directly with AKI. PRS was not associated with HIRI or AKI in the multivariable analyses.

Conclusion: Our results indicate that greater severity of liver graft injury during transplantation negatively affects renal function after OLT. As expected, the severity of liver graft steatosis contributes to accelerated liver injury occurring during the transplantation procedure.
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http://dx.doi.org/10.1111/aas.13556DOI Listing
July 2020

Type of Preservation Solution, UW or HTK, Has an Impact on the Incidence of Biliary Stricture following Liver Transplantation: A Retrospective Study.

J Transplant 2019 21;2019:8150736. Epub 2019 Dec 21.

Division of Transplantation Surgery, CLINTEC, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.

Organ preservation plays a crucial role in the outcome following solid organ transplantation. The aim of this study was to perform a retrospective outcome analysis following liver transplantation using histidine tryptophan ketoglutarate (HTK) or the University of Wisconsin (UW) solutions for liver graft preservation. We retrospectively reviewed data on adult patients who were liver-transplanted at Karolinska University Hospital between 2007 and 2015. There was evaluation of donor and recipient characteristics, pre- and post-transplant blood chemistry tests, biliary and vascular complications, graft dysfunction and nonfunction, and patient and graft survivals. A total of 433 patients were included in the analyses, with 230 and 203 patients having received livers preserved with HTK and UW, respectively. Mean follow-up was 45 ± 29 months for the HTK group and 42.4 ± 26 for the UW group. There was no difference between the two groups either in terms of patient and graft survival, or of results of postoperative blood chemistry, or incidence of arterial complications, early allograft dysfunction, or primary graft nonfunction. However, the incidence of biliary stricture was higher in the UW group (22.7%) versus the HTK group (13.5%; =0.013). Use of UW and HTK preservation solution in liver transplantation has no impact on patient and graft survival. However, use of HTK solution results in a lower incidence of posttransplant biliary stricture.
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http://dx.doi.org/10.1155/2019/8150736DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6942894PMC
December 2019

First European Case of Simultaneous Liver and Pancreas Transplantation as Treatment of Wolcott-Rallison Syndrome in a Small Child.

Transplantation 2020 03;104(3):522-525

Division of Transplantation Surgery, CLINTEC, Karolinska Institutet and Department of Transplantation Surgery, Karolinska University Hospital, Stockholm, Sweden.

Background: The concept of organ transplantation as treatment for complex genetic conditions, including Wolcott-Rallison syndrome (WRS), continues to show promise. Liver transplantation is essential for survival of patients with WRS, and pancreas transplantation cures their type I diabetes mellitus.

Methods: The recipient, a 3-year-old girl weighing 14 kg at the time of transplantation, suffered from major complications of WRS, including repetitive liver failure episodes and poorly controlled diabetes. The patient underwent a nonacute, combined, simultaneous liver and pancreas transplantation from a pediatric donor without using the en bloc technique.

Results: Well-preserved graft functions at 2-year follow-up with normal liver and pancreas function.

Conclusions: This is the first case report of simultaneous liver and pancreas transplantation as treatment of WRS in a small child in Europe. Two-year follow-up demonstrates that organ transplantation can halt life-threating recurrent liver failure episodes and cure type 1 diabetes.
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http://dx.doi.org/10.1097/TP.0000000000002869DOI Listing
March 2020

Characteristics and risk factors for recurrence of nonalcoholic steatohepatitis following liver transplantation.

Scand J Gastroenterol 2019 Feb 18;54(2):233-239. Epub 2019 Apr 18.

a Department of Clinical Science, Intervention and Technology, Division of Transplantation Surgery , Karolinska Institutet , Stockholm , Sweden.

Objectives: Nonalcoholic steatohepatitis (NASH), which is a common and increasing indication for liver transplantation (LT), is known to recur after LT. Since the recurrence of NASH can lead to graft failure, the identification of predictive factors is needed and preventive strategies should be implemented.

Methods: We retrospectively examined 95 patients who had undergone LT for NASH or alcoholic liver disease (ALD) as a primary indication. We evaluated peritransplant characteristics and histological findings 1-year post LT among liver transplant patients due to NASH or ALD.

Results: Pre-LT body mass index (BMI) was higher and pre-LT diabetes was more prevalent in NASH patients than in ALD patients (p < .01). The difference of BMI persisted at 3 months and 1 year after LT. There were no differences between the groups regarding histopathological findings including the degree of steatosis and fibrosis in 1-year biopsy. In multivariate analysis, recipient age and 1-year BMI were independent risk factors for post-LT fatty liver disease development. Regarding predictive factors of NASH recurrence, the prevalence of pre-LT insulin-dependent diabetes was significantly higher in patients who developed NASH recurrence than those who did not. The increase of HbA1c at 1-year post-LT checkup was higher in patients who developed recurrence than those who did not, although the difference did not reach statistical significance.

Conclusions: The results of this study suggest that insulin-dependent diabetes has detrimental effects on NASH recurrence following LT. Optimal glycemic control should be recommended, but studies are needed to prove its preventive effect on NASH recurrence.
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http://dx.doi.org/10.1080/00365521.2019.1577484DOI Listing
February 2019

Long-term Outcome of Endoscopic and Percutaneous Transhepatic Approaches for Biliary Complications in Liver Transplant Recipients.

Transplant Direct 2019 Mar 25;5(3):e432. Epub 2019 Feb 25.

Division of Transplantation Surgery, CLINTEC, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.

Background: Biliary complications occur in 6% to 34% of liver transplant recipients, for which endoscopic retrograde cholangiopancreatography has become widely accepted as the first-line therapy. We evaluated long-term outcome of biliary complications in patients liver transplanted between 2004 and 2014 at Karolinska University Hospital, Stockholm.

Methods: Data were retrospectively collected, radiological images were analyzed for type of biliary complication, and graft and patient survivals were calculated.

Results: In 110 (18.5%) of 596 transplantations, there were a total of 153 cases of biliary complications: 68 (44.4%) anastomotic strictures, 43 (28.1%) nonanastomotic strictures, 24 (15.7%) bile leaks, 11 (7.2%) cases of stone- and/or sludge-related problems, and 7 (4.6%) cases of mixed biliary complications. Treatment success rates for each complication were 90%, 73%, 100%, 82% and 80%, respectively. When the endoscopic approach was unsatisfactory or failed, percutaneous transhepatic cholangiography or a combination of treatments was often successful (in 18 of 24 cases). No procedure-related mortality was observed. Procedure-related complications were reported in 7.7% of endoscopic retrograde cholangiopancreatography and 3.8% of percutaneous transhepatic cholangiography procedures. Patient survival rates, 1, 3, 5, and 10 years posttransplant in patients with biliary complications were 92.7%, 80%, 74.7%, and 54.1%, respectively, compared with 92%, 86.6%, 83.7%, and 72.8% in patients free from biliary complications ( < 0.01). Similarly, long-term graft survival was lower in the group experiencing biliary complications ( < 0.0001).

Conclusions: Endoscopic and percutaneous approaches for treating biliary complications are safe and efficient and should be considered complementing techniques. Despite a high treatment success rate of biliary complications, their occurrence still has a significant negative impact on patient and graft long-term survivals.
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http://dx.doi.org/10.1097/TXD.0000000000000869DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6411220PMC
March 2019

Circulating Fibroblast Growth Factor 19 in Portal and Systemic Blood.

J Clin Exp Hepatol 2018 Jun 28;8(2):162-168. Epub 2017 Jul 28.

Division of Transplantation Surgery, Karolinska Institutet and Karolinska University Hospital Huddinge, Stockholm, Sweden.

Background: Bile acid homeostasis is essential and imbalance may lead to liver damage and liver failure. The bile acid induced intestinal factor fibroblast growth factor 19 (FGF19) has been identified as a key protein for mediating negative feedback inhibition of bile acid synthesis. The aim of the study was to define FGF19 and bile acid concentrations in portal and systemic blood in the fasted and postprandial state. We also addressed the question if physiological portal levels of FGF19 can be extrapolated from the concentration in systemic blood.

Methods: Portal and systemic blood was collected from 75 fasted patients undergoing liver surgery and from three organ donors before and after enteral nutrition. Serum concentration of FGF19 was determined with ELISA and bile acid concentration with gas chromatography-mass spectrometry.

Results: Concentration of bile acids was twice as high in portal compared to systemic blood in the fasted group and 3-5 times higher in the postprandial group. FGF19 increased after enteral nutrition but did not differ between portal and systemic blood, in either group. In addition, a strong, positive correlation between bile acids and FGF19 was found.

Conclusion: Our results confirm that bile acids drive the postprandial increase of circulating FGF19 but a hepatic clearance of FGF19 is unlikely. We conclude that systemic concentrations of FGF19 reflect portal concentrations of FGF19.
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http://dx.doi.org/10.1016/j.jceh.2017.07.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5992265PMC
June 2018

Albumin mass balance and kinetics in liver transplantation.

Crit Care 2018 06 7;22(1):152. Epub 2018 Jun 7.

Perioperative Medicine and Intensive Care, B31, Karolinska University Hospital, Huddinge, SE-141 86, Stockholm, Sweden.

Background: In major abdominal surgery albumin is shifted from the circulation, presumably leaking into the interstitial space, contributing to a 30-40% decrease in plasma albumin concentration. During and after liver transplantation exogenous albumin is infused for volume substitution and to maintain plasma albumin concentration. Here we used liver transplantation as a model procedure for the study of albumin mass balance and kinetics during major abdominal surgery with albumin substitution.

Methods: Patients were studied during liver transplantation (n = 16), and until postoperative day 3 (POD 3) (n = 11). Cumulative perioperative albumin shift was assessed by mass balance of albumin and hemoglobin. Synthesis rates of albumin and fibrinogen were estimated by the flooding technique using deuterium-labeled phenylalanine. Albumin distribution was assessed by radioiodinated human serum albumin.

Results: At the end of surgery, 37 ± 17 g of albumin (p < 0.0001) had shifted from plasma, and this amount was stable until POD 3 (48 ± 33 g, p = 0.0017 versus baseline). There was 91 ± 37 g exogenous albumin infused peroperatively and another 47 ± 35 g was infused postoperatively until POD 3. Absolute synthesis rates of albumin and fibrinogen on POD 3 were 239 ± 84 mg/kg body weight/day and 33 mg/kg body weight/day (range 5-161), respectively.

Conclusions: Albumin net leakage from plasma progressed until the end of surgery, and was then unaltered until POD 3. This is in contrast with the normalization of the cumulative albumin shift identified at day 3 after non-transplant major abdominal surgery. Liver synthesis of export proteins was high compared to reference values at the third postoperative day, suggesting rapid recovery of synthesis capacity.

Trial Registration: Swedish Medical Product Agency, EudraCT 2015-002568-18. Registered on 15 July 2015.
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http://dx.doi.org/10.1186/s13054-018-2053-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5992699PMC
June 2018

Serial Assessment of Growth Factors Associated with Liver Regeneration in Patients Operated with Associating Liver Partition and Portal Vein Ligation for Staged Hepatectomy.

Eur Surg Res 2018 2;59(1-2):72-82. Epub 2018 May 2.

Division of Surgery, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.

Background: There is limited knowledge about the mechanisms behind the unparalleled growth of the future liver remnant (FLR) linked to associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). In this study, liver regenerative markers were examined in patients subjected to ALPPS.

Methods: Ten patients with colorectal liver metastases treated with neoadjuvant chemotherapy and ALPPS were included. Plasma was sampled at 6 time points and biopsies from both liver lobes were collected at both stages of ALPPS. The levels of interleukin (IL)-6, hepatocyte growth factor (HGF), tumor necrosis factor-α, epidermal growth factor, and vascular endothelial growth factor in plasma were measured at each time point. Expression of mRNA for markers of proliferation and apoptosis was studied in the biopsies from both liver lobes taken at both stages.

Results: ALPPS resulted in a peak of IL-6 after stage 1 (p = 0.004), which decreased rapidly and did not increase again after stage 2. HGF also increased after stage 1 (p = 0.048), and the HGF levels correlated significantly with the degree of growth of the FLR before stage 2 (p = 0.02, r2 = 0.47). There was a correlation between peak levels of IL-6 and HGF (p = 0.03, r2 = 0.84).

Conclusions: IL-6 and HGF seem to be early mediators of hypertrophy after stage 1 in the ALPPS procedure. The peak HGF plasma level correlates with the degree of FLR growth in patients subjected to ALPPS.
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http://dx.doi.org/10.1159/000488078DOI Listing
November 2018

The molecular adsorbent recirculating system in posthepatectomy liver failure: Results from a prospective phase I study.

Hepatol Commun 2018 04 8;2(4):445-454. Epub 2018 Mar 8.

Department for Clinical Science, Intervention and Technology Karolinska InstituteStockholmSweden.

Posthepatectomy liver failure (PHLF) represents the single most important cause of postoperative mortality after major liver resection, yet no effective treatment option is available. Extracorporeal liver support devices might be helpful, but systematic studies are lacking. Accordingly, we aimed to assess the safety and feasibility of the Molecular Adsorbent Recirculating System (MARS) in patients with PHLF. Between December 2012 and May 2015, a total of 206 patients underwent major or extended hepatectomy, and 10 consecutive patients with PHLF (according to the Balzan 50:50 criteria) were enrolled into the study. MARS treatment was initiated on postoperative day 5-7, and five to seven consecutive treatment sessions were completed for each patient. In total, 59 MARS cycles were implemented, and MARS was initiated and completed without major complications in any patient. However, 1 patient developed an immense asymptomatic hyperbilirubinemia (without encephalopathy), 1 had repeated clotting problems in the MARS filter, and 2 patients experienced access problems with the central venous line. Otherwise, no adverse events were observed. In 9 patients, the bilirubin level and international normalized ratio decreased significantly ( 0.05) during MARS treatment. The 60- and 90-day mortality was 0% and 10%, respectively. Among the 9 survivors, 4 still had liver dysfunction at 90 days postoperatively. Five patients were alive 1 year postoperatively without any signs of liver dysfunction or disease recurrence. The use of MARS in PHLF is feasible and safe and improves liver function in patients with PHLF. In the present study, 60- and 90-day mortality rates were unexpectedly low compared to a historical control group. The impact of MARS treatment on mortality in PHLF should be further evaluated in a randomized controlled clinical trial. ( 2018;2:445-454).
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http://dx.doi.org/10.1002/hep4.1167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5880195PMC
April 2018

Morphological alterations and redox changes associated with hepatic warm ischemia-reperfusion injury.

World J Hepatol 2017 Dec;9(34):1261-1269

Department of Clinical Science, Intervention, and Technology (CLINTEC), Division of Surgery, Karolinska Institutet, Karolinska University Hospital, Huddinge, Stockholm S-141 86, Sweden.

Aim: To study the effects of warm ischemia-reperfusion (I/R) injury on hepatic morphology at the ultrastructural level and to analyze the expression of the thioredoxin (TRX) and glutaredoxin (GRX) systems.

Methods: Eleven patients undergoing liver resection were subjected to portal triad clamping (PTC). Liver biopsies were collected at three time points; first prior to PTC (baseline), 20 min after PTC (post-ischemia) and 20 min after reperfusion (post-reperfusion). Electron microscopy and morphometry were used to study and quantify ultrastructural changes, respectively. Additionally, gene expression analysis of TRX and GRX isoforms was performed by quantitative PCR. For further validation of redox protein status, immunogold staining was performed for the isoforms GRX1 and TRX1.

Results: Post-ischemia, a significant loss of the liver sinusoidal endothelial cell (LSEC) lining was observed (P = 0.0003) accompanied by a decrease of hepatocyte microvilli in the space of Disse. Hepatocellular morphology was well preserved apart from the appearance of crystalline mitochondrial inclusions in 7 out of 11 patients. Post-reperfusion biopsies had similar features as post-ischemia with the exception of signs of a reactivation of the LSECs. No changes in the expression of redox-regulatory genes could be observed at mRNA level of the isoforms of the TRX family but immunoelectron microscopy indicated a redistribution of TRX1 within the cell.

Conclusion: At the ultrastructural level, the major impact of hepatic warm I/R injury after PTC was borne by the LSECs with detachment and reactivation at ischemia and reperfusion, respectively. Hepatocytes morphology were well preserved. Crystalline inclusions in mitochondria were observed in the hepatocyte after ischemia.
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http://dx.doi.org/10.4254/wjh.v9.i34.1261DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5740095PMC
December 2017

Defining Benchmarks in Liver Transplantation: A Multicenter Outcome Analysis Determining Best Achievable Results.

Ann Surg 2018 03;267(3):419-425

Department of Surgery and Transplantation, Swiss HPB Center Zurich, University Hospital Zurich, Zurich, Switzerland.

: This multicentric study of 17 high-volume centers presents 12 benchmark values for liver transplantation. Those values, mostly targeting markers of morbidity, were gathered from 2024 "low risk" cases, and may serve as reference to assess outcome of single or any groups of patients.

Objective: To propose benchmark outcome values in liver transplantation, serving as reference for assessing individual patients or any other patient groups.

Background: Best achievable results in liver transplantation, that is, benchmarks, are unknown. Consequently, outcome comparisons within or across centers over time remain speculative.

Methods: Out of 7492 liver transplantation performed in 17 international centers from 3 continents, we identified 2024 low risk adult cases with a laboratory model for end-stage liver disease score ≤20 points, a balance of risk score ≤9, and receiving a primary graft by donation after brain death. We chose clinically relevant endpoints covering intra- and postoperative course, with a focus on complications graded by severity including the complication comprehensive index (CCI). Respective benchmarks were derived from the median value in each center, and the 75 percentile was considered the benchmark cutoff.

Results: Benchmark cases represented 8% to 49% of cases per center. One-year patient-survival was 91.6% with 3.5% retransplantations. Eighty-two percent of patients developed at least 1 complication during 1-year follow-up. Biliary complications occurred in one-fifth of the patients up to 6 months after surgery. Benchmark cutoffs were ≤4 days for ICU stay, ≤18 days for hospital stay, ≤59% for patients with severe complications (≥ Grade III) and ≤42.1 for 1-year CCI. Comparisons with the next higher risk group (model for end stage liver disease 21-30) disclosed an increase in morbidity but within benchmark cutoffs for most, but not all indicators, while in patients receiving a second graft from 1 center (n = 50) outcome values were all outside of benchmark values.

Conclusions: Despite excellent 1-year survival, morbidity in benchmark cases remains high with half of patients developing severe complications during 1-year follow-up. Benchmark cutoffs targeting morbidity parameters offer a valid tool to assess higher risk groups.
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http://dx.doi.org/10.1097/SLA.0000000000002477DOI Listing
March 2018

Exogenous alpha 1-antitrypsin down-regulates SERPINA1 expression.

PLoS One 2017 9;12(5):e0177279. Epub 2017 May 9.

Division of Transplantation Surgery, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institute, Karolinska University Hospital Huddinge, Stockholm, Sweden.

The main goal of the therapy with purified human plasma alpha1-antitrypsin (A1AT) is to increase A1AT levels and to prevent lungs from elastolytic activity in patients with PiZZ (Glu342Lys) A1AT deficiency-related emphysema. Potential hepatic gains of this therapy are unknown. Herein, we investigated the effect of A1AT therapy on SERPINA1 (gene encoding A1AT) expression. The expression of SERPINA1 was determined in A1AT or A1AT plus Oncostatin M (OSM) treated primary human hepatocytes isolated from liver tissues from A1AT deficient patients and control liver tissues. In addition, SERPINA1 mRNA was assessed in lung tissues from PiZZ emphysema patients with and without A1AT therapy, and in adherent human peripheral blood mononuclear cells (PBMC) isolated from healthy PiMM donors. In a dose-dependent manner purified A1AT lowered SERPINA1 expression in hepatocytes. This latter effect was more prominent in hepatocytes stimulated with OSM. Although it did not reach statistical significance (P = 0.0539)-analysis of lung tissues showed lower SERPINA1 expression in PiZZ emphysema patients receiving augmentation therapy relative to those without therapy. Finally, exogenously added purified A1AT (1mg/ml) reduced SERPINA1 expression in naïve as well as in lipopolysaccharide (LPS)-stimulated human adherent PBMCs. Exogenous A1AT protein reduces its own endogenous expression. Hence, augmentation with native M-A1AT protein and a parallel reduction in expression of dysfunctional mutant Z-A1AT may be beneficial for PiZZ liver, and this motivates further studies.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0177279PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5423693PMC
September 2017

Domino liver transplantation: full-length transthyretin in donor and recipient patients with ATTR Val30Met amyloidosis.

Amyloid 2017 Mar;24(sup1):128-129

b Division of Transplantation Surgery , CLINTEC, Karolinska Institutet and Karolinska University Hospital , Stockholm , Sweden , and.

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http://dx.doi.org/10.1080/13506129.2017.1294058DOI Listing
March 2017

Severe Transplantation-Mediated Alloimmune Thrombocytopenia in 2 Recipients of Organs From the Same Donor.

Transplantation 2017 05;101(5):e190-e192

1 Department of Transplant Surgery, Karolinska University Hospital, Stockholm, Sweden. 2 Division of Clinical Science Intervention and Technology, Karolinska Institute, Stockholm, Sweden. 3 Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, Stockholm, Sweden. 4 Division of Medicine, Karolinska Institute, Stockholm, Sweden. 5 Department of Laboratory Medicine, Karolinska Institute, Stockholm, Sweden.

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http://dx.doi.org/10.1097/TP.0000000000001669DOI Listing
May 2017

Mortality-related risk factors and long-term survival after 4460 liver resections in Sweden-a population-based study.

Langenbecks Arch Surg 2017 Feb 1;402(1):105-113. Epub 2016 Oct 1.

Institution for Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Solna, Sweden.

Purpose: The objectives of this study were to analyze the outcome after hepatectomy and to identify contributing factors to mortality and long-term survival in a population-based setting.

Method: A retrospective, nationwide register study was performed. All patients who underwent hepatectomy in Sweden between 2002 and 2011 were identified in the Swedish Hospital Discharge Registry using their unique personal identification numbers. This cohort was linked to the National Cancer Registry (cancer diagnosis), the National Registry of Causes of Death, and the Migration Registry. Survival analysis by Kaplan-Meier method was performed to assess long-term outcome. A Cox regression model was used to analyze risk factors affecting long-term survival.

Results: Overall, 4460 hepatectomies were performed. The 30- and 90-day mortalities were 1.8 and 3.1 %, respectively. The overall 5- and 10-year survival rates for all diagnoses were 45 and 38 %, respectively. Independent risk factors for 5-year mortality were as follows: patient age, comorbidity, male gender, intrahepatic/extrahepatic cholangiocarcinoma, gallbladder cancer, extent of hepatectomy, and hepatectomies performed at non-university hospitals. Re-resection (78.1 % with diagnosis "metastasis") was performed on 374 patients. In these patients, mortality risk decreased by >50 % (HR 0.42; 95 %, CI 0.33-0.53).

Conclusion: In a population-based analysis, liver resections are done with a low mortality risk and good long-term outcome. Patients who underwent resection at a University Hospital showed a significant better outcome compared to patients resected at non-University Hospitals. These results support further centralization of liver surgery. Re-resection should be performed if feasible.
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http://dx.doi.org/10.1007/s00423-016-1512-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5309267PMC
February 2017

Changes in gluconeogenesis and intracellular lipid accumulation characterize uremic human hepatocytes ex vivo.

Am J Physiol Gastrointest Liver Physiol 2016 06 7;310(11):G952-61. Epub 2016 Apr 7.

Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden; and Department of Immunology, Karolinska University Hospital, Stockholm, Sweden

It is well known that reduced glomerular filtration rate (GFR) leads to an increased risk of dyslipidemia, insulin resistance, and cardiovascular mortality. The liver is a central organ for metabolism, but its function in the uremic setting is still poorly characterized. We used human primary hepatocytes isolated from livers of nine donors with normal renal function to investigate perturbations in key metabolic pathways following exposure to uremic (n = 8) or healthy (n = 8) sera, and to serum-free control medium. Both uremic and healthy elicited consistent responses from hepatocytes from multiple donors and compared with serum-free control. However, at physiological insulin concentrations, uremic cells accumulated 56% more intracellular lipids. Also, when comparing uremic with healthy medium after culture, it contained more very-low-density lipoprotein-triglyceride and glucose. These changes were accompanied by decreased phosphorylation of AktS473 mRNA levels of key regulators of gluconeogenesis in uremic sera-treated hepatocytes such as phosphoenolpyruvate carboxykinase 1 and glucose 6-phosphate were elevated. We also found increased expression of 11β-hydroxysteroid dehydrogenase mRNA in uremic cells, along with high phosphorylation of downstream p53 and phospholipase C-γ1Y783 Thus our ex vivo data suggest that the uremic hepatocytes rapidly develop a glycogenic and lipogenic condition accompanied by perturbations in a large number of signaling networks.
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http://dx.doi.org/10.1152/ajpgi.00379.2015DOI Listing
June 2016

Liver transplantation in the Nordic countries - An intention to treat and post-transplant analysis from The Nordic Liver Transplant Registry 1982-2013.

Scand J Gastroenterol 2015 Jun;50(6):797-808

Section for Transplantation Surgery, Department of Transplantation Medicine, Division of Cancer, Surgery and Transplantation, Oslo University Hospital , Oslo , Norway.

Aim And Background: The Nordic Liver Transplant Registry (NLTR) accounts for all liver transplants performed in the Nordic countries since the start of the transplant program in 1982. Due to short waiting times, donor liver allocation has been made without considerations of the model of end-stage liver disease (MELD) score. We aimed to summarize key outcome measures and developments for the activity up to December 2013.

Materials And Methods: The registry is integrated with the operational waiting-list and liver allocation system of Scandiatransplant (www.scandiatransplant.org) and accounted at the end of 2013 for 6019 patients out of whom 5198 were transplanted. Data for recipient and donor characteristics and relevant end-points retransplantation and death are manually curated on an annual basis to allow for statistical analysis and the annual report.

Results: Primary sclerosing cholangitis, acute hepatic failure, alcoholic liver disease, primary biliary cirrhosis and hepatocellular carcinoma are the five most frequent diagnoses (accounting for 15.3%, 10.8%, 10.6%, 9.3% and 9.0% of all transplants, respectively). Median waiting time for non-urgent liver transplantation during the last 10-year period was 39 days. Outcome has improved over time, and for patients transplanted during 2004-2013, overall one-, five- and 10-year survival rates were 91%, 80% and 71%, respectively. In an intention-to-treat analysis, corresponding numbers during the same time period were 87%, 75% and 66%, respectively.

Conclusion: The liver transplant program in the Nordic countries provides comparable outcomes to programs with a MELD-based donor liver allocation system. Unique features comprise the diagnostic spectrum, waiting times and the availability of an integrated waiting list and transplant registry (NLTR).
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http://dx.doi.org/10.3109/00365521.2015.1036359DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4487534PMC
June 2015

Transplantation With Livers From Deceased Donors Older Than 75 Years.

Transplantation 2015 Dec;99(12):2534-42

1 Department of Transplantation Medicine, Section for Transplant Surgery, Oslo University Hospital, Oslo, Norway. 2 Biotechnology Centre of Oslo, University of Oslo, Oslo, Norway. 3 Centre for Molecular Medicine Norway, Nordic EMBL Partnership, University of Oslo, Oslo, Norway. 4 Department of Transplantation, Institute of Clinical Sciences, Sahlgrenska Academy, Sahlgrenska University Hospital, Gothenburg, Sweden. 5 Division of Transplantation Surgery, Karolinska University Hospital Huddinge, Solna, Sweden. 6 Department of Surgical Sciences, Upper Abdominal Surgery, Uppsala Academic Hospital, Uppsala, Sweden. 7 Transplantation and Liver Surgery Clinic, Helsinki University Hospital, Helsinki, Finland. 8 Department of Surgical Gastroenterology and Transplantation, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark. 9 Division of Cancer medicine, Surgery and Transplantation, Department of Transplantation Medicine, Norwegian PSC Research Centre, Oslo University Hospital, Rikshospitalet, Oslo, Norway. 10 Institute for Clinical Medicine, University of Oslo, Oslo, Norway.

Background: The availability of donor organs limits the number of patients in need who are offered liver transplantation. Measures to expand the donor pool are crucial to prevent on-list mortality. The aim of this study was to evaluate the use of livers from deceased donors who were older than 75 years.

Methods: Fifty-four patients who received a first liver transplant (D75 group) from 2001 to 2011 were included. Donor and recipient data were collected from the Nordic Liver Transplant Registry and medical records. The outcome was compared with a control group of 54 patients who received a liver graft from donors aged 20 to 49 years (D20-49 group). Median donor age was 77 years (range, 75-86 years) in the D75 group and 41 years (range, 20-49 years) in the D20-49 group. Median recipient age was 59 years (range, 31-73 years) in the D75 group and 58 years (range, 31-74 years) in the D20-49 group.

Results: The 1-, 3-, and 5-year patient/graft survival values were 87/87%, 81/81%, and 71/67% for the D75 group and 88/87%, 75/73%, and 75/73% for the D20-49 group, respectively. Patient (P = 0.89) and graft (P = 0.79) survival did not differ between groups. The frequency of biliary complications was higher in the D75 group (29.6/13%, P = 0.03).

Conclusions: Selected livers from donors over age 75 years should not be excluded based on age, which does not compromise patient or graft survival despite a higher frequency of biliary complications.
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http://dx.doi.org/10.1097/TP.0000000000000728DOI Listing
December 2015

Strategies for short-term storage of hepatocytes for repeated clinical infusions.

Cell Transplant 2014 ;23(8):1009-18

Division of Transplantation Surgery, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institute, Karolinska University Hospital Huddinge, Stockholm, Sweden.

Hepatocyte transplantation is an upcoming treatment for patients with metabolic liver diseases. Repeated cell infusions over 1-2 days improve clinical outcome. Isolated hepatocytes are usually cold stored in preservation solutions between repeated infusions. However, during cold storage isolated hepatocytes undergo cell death. We investigated if tissue preservation and repeated isolations are better than storage of isolated hepatocytes when cold preserving human hepatocytes. Liver tissue obtained from liver surgery or organ donors was divided into two pieces. Hepatocytes were isolated by collagenase digestion. Hepatocytes were analyzed directly after isolation (fresh) or after storage for 48 h at 4°C in University of Wisconsin solution (UW cells). Liver tissue from the same donor was stored at 4°C in UW and hepatocytes were isolated after 48 h (UW tissue cells). Hepatocyte viability and function was evaluated by trypan blue exclusion, plating efficiency, ammonia metabolism, CYP 1A1/2, 2C9, 3A7, and 3A4 activities, phase II conjugation, and apoptosis evaluation by TUNEL assay and caspase-3/7 activities. Hepatocytes stored in UW showed a significantly lower viability compared to fresh cells or hepatocytes isolated from tissue stored for 48 h (54% vs. 71% vs. 79%). Plating efficiency was significantly decreased for cells stored in UW (40%) compared to fresh and UW tissue cells (63% vs. 55%). No significant differences between UW cells and UW tissue cells could be shown for CYP activities or ammonia metabolism. Hepatocytes stored in UW showed a strong increase in TUNEL-positive cells, whereas TUNEL staining in cold-stored liver tissue and hepatocytes isolated after 48 h was unchanged. This observation was confirmed by increased caspase-3/7 activities in UW cells. Although preservation of isolated hepatocytes in UW maintains function, cold storage of liver tissue and repeated hepatocyte isolations is superior to cold storage of isolated hepatocytes in preserving hepatocyte viability and function.
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http://dx.doi.org/10.3727/096368913X667484DOI Listing
May 2015

Endocardial border delineation capability of a novel multimodal polymer-shelled contrast agent.

Cardiovasc Ultrasound 2014 Jul 3;12:24. Epub 2014 Jul 3.

Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Alfred Nobels Allé 10, 141 52 Huddinge, Sweden.

Background: A novel polymer-shelled contrast agent (CA) with multimodal and target-specific potential was developed recently. To determine its ultrasonic diagnostic features, we evaluated the endocardial border delineation as visualized in a porcine model and the concomitant effect on physiological variables.

Methods: Three doses of the novel polymer-shelled CA (1.5 ml, 3 ml, and 5 ml [5 × 10(8) microbubbles (MBs)/ml]) and the commercially available CA SonoVue (1.5 ml [2-5 × 10(8) MBs/ml]) were used. Visual evaluations of ultrasound images of the left ventricle were independently performed by three observers who graded each segment in a 6-segment model as either 0 = not visible, 1 = weakly visible, or 2 = visible. Moreover, the duration of clinically useful contrast enhancement and the left ventricular opacification were determined. During anesthesia, oxygen saturation, heart rate, and arterial pressure were sampled every minute and the effect of injection of CA on these physiological variables was evaluated.

Results: The highest dose of the polymer-shelled CA gave results comparable to SonoVue. Thus, no significant difference in the overall segment score distribution (2-47-95 vs. 1-39-104), time for clinically sufficient contrast enhancement (20-40 s for both) and left ventricular overall opacification was found. In contrast, when comparing the endocardial border delineation capacity for different regions SonoVue showed significantly higher segment scores for base and mid, except for the mid region when injecting 1.5 ml of the polymer-shelled CA. Neither high nor low doses of the polymer-shelled CA significantly affected the investigated physiological variables.

Conclusions: This study demonstrated that the novel polymer-shelled CA can be used in contrast-enhanced diagnostic imaging without influence on major physiological variables.
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http://dx.doi.org/10.1186/1476-7120-12-24DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4094688PMC
July 2014

Membrane cut-off does not influence results regarding the measurement of small molecules - a comparative study between 20- and 100-kDa catheters in hepatic microdialysis.

Clin Physiol Funct Imaging 2014 Mar 18;34(2):109-13. Epub 2013 Aug 18.

Division of Surgery, Department of Clinical Science, Intervention, and Technology (CLINTEC), Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.

Background: Microdialysis is a method used to monitor hepatic tissue metabolism. Membranes with a molecular cut-off of 20 kilodalton (kDa) are currently used to measure the small metabolites glucose, glycerol, lactate and pyruvate. Using membranes with higher cut-off such as 100 kDa allows the possibility of measuring larger molecules but may affect results regarding small molecules. The aim was to compare microdialysis catheters with a cut-off of 20 and 100 kDa in the measurement of small molecules in a pig liver model.

Methods: Four microdialysis catheters were inserted into the liver of each pig used in the experiment (n = 6). Two catheters with cut-off of 20 kDa were perfused with Ringer acetate, and two catheters with cut-off of 100 kDa: one perfused with Ringer acetate and one with hydroxyethyl starch (Voluven) at a flow rate of 0·3 μl min(-1). Dialysate samples were collected at 40-min intervals and analysed for glucose, glycerol, lactate and pyruvate.

Results: Compared to the other catheters, the 100-kDa catheters perfused with Ringer acetate tended to measure higher dialysate concentrations of the small molecules, the difference reaching statistical significance in the case of pyruvate. Concentrations measured by the 100-kDa catheters perfused with Voluven were, however, comparable to the 20-kDa catheters.

Conclusions: Microdialysis catheters with membrane cut-off of 20 and 100 kDa can be used equally in hepatic microdialysis for the monitoring of glucose, glycerol, lactate and pyruvate, and lactate/pyruvate ratio if a high osmotic solution (Voluven) is used to perfuse the 100-kDa catheters.
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http://dx.doi.org/10.1111/cpf.12071DOI Listing
March 2014

Hepatocyte transplantation ameliorates the metabolic abnormality in a mouse model of acute intermittent porphyria.

Cell Transplant 2014 ;23(9):1153-62

Division of Transplantation Surgery, Department for Clinical Science, Intervention and Technology CLINTEC, Karolinska University Hospital, Stockholm, Sweden.

Acute intermittent porphyria (AIP) is an autosomal dominant disorder characterized by insufficient porphobilinogen deaminase (PBGD) activity. When hepatic heme synthesis is induced, porphobilinogen (PBG) and 5-aminolevulinic acid (ALA) accumulate, which causes clinical symptoms such as abdominal pain, neuropathy, and psychiatric disturbances. Our aim was to investigate if hepatocyte transplantation can prevent or minimize the metabolic alterations in an AIP mouse model. We transplanted wild-type hepatocytes into PBGD-deficient mice and induced heme synthesis with phenobarbital. ALA and PBG concentrations in plasma were monitored, and the gene transcriptions of hepatic enzymes ALAS1, PBGD, and CYP2A5 were analyzed. Results were compared with controls and correlated to the percentage of engrafted hepatocytes. The accumulation of ALA and PBG was reduced by approximately 50% after the second hepatocyte transplantation. We detected no difference in mRNA levels of PBGD, ALAS1, or CYP2A5. Engraftment corresponding to 2.7% of the total hepatocyte mass was achieved following two hepatocyte transplantations. A lack of precursor production in less than 3% of the hepatocytes resulted in a 50% reduction in plasma precursor concentrations. This disproportional finding suggests that ALA and PBG produced in PBGD-deficient hepatocytes crossed cellular membranes and was metabolized by transplanted cells. The lack of effect on enzyme mRNA levels suggests that no significant efflux of heme from normal to PBGD-deficient hepatocytes takes place. Further studies are needed to establish the minimal number of engrafted hepatocytes needed to completely correct the metabolic abnormality in AIP and whether amelioration of the metabolic defect by partial restoration of PBGD enzyme activity translates into a clinical effect in human AIP.
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http://dx.doi.org/10.3727/096368913X666980DOI Listing
May 2015