The remarkable difference in success rates between clinical pancreas transplantation and islet transplantation is poorly understood. Despite the same histocompatibility barrier and similar immunosuppressive treatments in both transplantation procedures, human intraportal islet transplantation has a much inferior success rate than does vascularized pancreas transplantation. Thus far, little attention has been directed to the possibility that islets transplanted into the blood stream may elicit an injurious incompatibility reaction. We have tested this hypothesis in vitro with human islets and in vivo with porcine islets. Human islets were exposed to nonanticoagulated human ABO-compatible blood in surface-heparinized polyvinyl chloride tubing loops. Heparin and/or the soluble complement receptor 1 (sCR1) TP10 were tested as additives. Adult porcine islets were transplanted intraportally into pigs, and the liver was recovered after 60 min for immunohistochemical staining. Human islets induced a rapid consumption and activation of platelets. Neutrophils and monocytes were also consumed, and the coagulation and complement systems were activated. Upon histological examination, islets were found to be embedded in clots and infiltrated with CD11+ leukocytes. Furthermore, the cellular morphology was disrupted. When heparin and sCR1 were added to the blood, these events were avoided. Porcine islets retrieved in liver biopsies after intraportal islet allotransplantation showed a morphology similar to that of human islets perifused in vitro. Thus, exposure of isolated islets of Langerhans to allogenic blood resulted in significant damage to the islets, a finding that could explain the unsatisfactory clinical results obtained with intraportal islet transplantation. Because administration of heparin in combination with a soluble complement receptor abrogated these events, such treatment would presumably improve the outcome of clinical islet transplantation by reducing both initial islet loss and subsequent specific immune responses.

Summary The purpose of this registry study was to provide an overview of trends and results of liver transplantation (LT) in Europe from 1968 to 2016. These data on LT were collected prospectively from 169 centers from 32 countries, in the European Liver Transplant Registry (ELTR) beginning in 1968. This overview provides epidemiological data, as well as information on evolution of techniques, and outcomes in LT in Europe over more than five decades; something that cannot be obtained from only a single center experience.

Islet transplantation offers a logical means to treat insulin-dependent diabetes. However, for reasons poorly understood, the clinical results with islet transplantation have been vastly inferior to those obtained with whole organ pancreas transplantation. The conventional technique for transplanting isolated islets is by intraportal injection, with the islets being trapped in the liver. Human islets exposed to human blood trigged an "instant blood mediated inflammatory reaction", IBMIR, characterised by platelet consumption, and activation of the coagulation and complement systems. The islets became surrounded by clots and infiltrated with leukocytes, and there was evidence of islet damage as reflected in insulin dumping. When heparin and a complement inhibitor (SCRI), was added to the system, IBMIR was suppressed and islet damage reduced. After intraportal pig-to-pig islet intraportal allotransplantation similar morphological changes was found, corroborating the in vitro findings. Thus, IBMIR inflicts a significant damage to human islets exposed to human blood and IBMIR will also, most likely, enhance the subsequent specific, cell mediated, rejection. Platelet and complement activation seem to be the most important factors in the pathogenesis of IBMIR. The results presented strongly suggest that IBMIR observed both in vitro and in vivo when isolated islets come in contact with blood could provide an explanation for the unsatisfactory results seen in clinical islet allotransplantation.

Exposure of isolated xenogeneic islets of Langerhans to blood, both in vitro and in vivo, resulted in acute islet damage. Complement and platelets seem to have a central role in the reactions described. Strategies to efficiently inhibit these reactions will be crucial for clinical intraportal islet xenotransplantation to be successful.

Dramatic improvement in first-year outcomes post-liver transplantation (LT) has shifted attention to long-term survival, where efforts are now needed to achieve improvement. Understanding the causes of premature death is a prerequisite for improving long-term outcome. Overall and cause-specific mortality of 3,299 Nordic LT patients having survived 1 year post-LT were divided by expected rates in the general population, adjusted for age, sex, calendar date, and country to yield standardized mortality ratios (SMRs). Data came from the Nordic Liver-Transplant Registry and WHO mortalityindicator database. Stagnant patient survival rates >1 year post-LT were 21% lower at 10 years than expected survival for the general population. Overall SMR for death before age 75 (premature mortality) was 5.8 (95% confidence interval [CI] 5.4-6.3), with improvement from 1985-1999 to 2000-2010 in hepatitis C (HCV) (SMR change 23.1-9.2), hepatocellular carcinoma (HCC) (SMR 38.4-18.8), and primary sclerosing cholangitis (SMR 11.0-4.2), and deterioration in alcoholic liver disease (8.3-24.0) and acute liver failure (ALF) (5.9-7.6). SMRs for cancer and liver disease (recurrent or transplant-unrelated disease) were elevated in all indications except primary biliary cirrhosis (PBC). Absolute mortality rates underestimated the elevated premature mortality from infections (SMR 22-693) and kidney disease (SMR 13-45) across all indications, and from suicide in HCV and ALF. SMR for cardiovascular disease was significant only in PBC and alcoholic liver disease, owing to high mortality in the general population. Transplant-specific events caused 16% of deaths. Conclusion: standardized premature mortality provided an improved picture of long-term post-LT outcome, showing improvement over time in some indications, not revealed by overall absolute mortality rates. Causes with high premature mortality (infections, cancer, kidney and liver disease, and suicide) merit increased attention in clinical patient follow-up and future research. (HEPATOLOGY 2015;61:668-677)