Prevalence of Steatosis Hepatis in the Eurotransplant Region: Impact on Graft Acceptance Rates

Due to the shortage of liver allografts and the rising prevalence of fatty liver disease in the general population, steatotic liver grafts are considered for transplantation.This condition is an important risk factor for the outcome after transplantation.We here analyze the characteristics of the donor pool offered to the Charité –Universitätsmedizin Berlin from 2010 to 2016 with respect to liver allograft nonacceptance and steatosis hepatis. Of the 2653 organs offered to our center, 19.9% (n=527) were accepted for transplantation, 58.8% (n=1561) were allocated to other centers, and 21.3% (n = 565) were eventually discarded from transplantation. In parallel to an increase of the incidence of steatosis hepatis in the donor pool from 20% in 2010 to 30% in 2016, the acceptance rates for steatotic organs increased in our center from 22.3% to 51.5% in 2016 (p 0.001) having less than 30% macrovesicular steatosis hepatis. However, by 2016, the number of canceled transplantations due to higher grades of steatosis hepatis had significantly increased from 14.7% (n = 15) to 63.6% (42; p < 0.001).The rising prevalence of steatosis hepatis in the donor pool has led to higher acceptance rates of steatotic allografts. Nonetheless, steatosis hepatis remains a predominant phenomenon in discarded organs necessitating future concepts such as organ reconditioning to increase graft utilization

Dual versus single vessel normothermic ex vivo perfusion of rat liver grafts using metamizole for vasodilatation

Background: Normothermic ex vivo liver perfusion (NEVLP) is a promising strategy to increase the donor pool in liver transplantation. Small animal models are essential to further investigate questions regarding organ preservation and reconditioning by NEVLP. A dual vessel small animal NEVLP (dNEVLP) model was developed using metamizole as a vasodilator and compared to conventional portovenous single vessel NEVLP (sNEVLP). Methods: Livers of male Wistar rats were perfused with erythrocyte-supplemented culture medium for six hours by either dNEVLP via hepatic artery and portal vein or portovenous sNEVLP. dNEVLP was performed either with or without metamizole treatment. Perfusion pressure and flow rates were constantly monitored. Transaminase levels were determined in the perfusate at the start and after three and six hours of perfusion. Bile secretion was monitored and bile LDH and GGT levels were measured hourly. Histopathological analysis was performed using liver and bile duct tissue samples after perfusion. Results: Hepatic artery pressure was significantly lower in dNEVLP with metamizole administration. Compared to sNEVLP, dNEVLP with metamizole treatment showed higher bile production, lower levels of transaminases during and after perfusion as well as significantly lower necrosis in liver and bile duct tissue. Biochemical markers of bile duct injury showed the same trend. Conclusion: Our miniaturized dNEVLP system enables normothermic dual vessel rat liver perfusion. The administration of metamizole effectively ameliorates arterial vasospasm allowing for six hours of dNEVLP, with superior outcome compared to sNEVLP

Metabolic reconditioning of steatotic rat livers using ex-vivo maschine perfusion and mTOR inhibition

Einleitung: Die Lebertransplantation stellt bis heute das einzige Verfahren zur kurativen Therapie von PatientInnen mit terminalem Leberversagen dar. Demographischer Wandel und eine wachsende Prävalenz des metabolischen Syndroms führen zunehmend zu einer minderen Organqualität der zur Verfügung stehenden Transplantate. Die Transplantation von Lebern mit makrovesikulärer Steatose ist mit einem deutlich erhöhten Risiko für ein Transplantatversagen assoziiert. Ziel dieser Arbeit war es, im Tiermodell ein pharmakologisches Verfahren zur Konditionierung steatotischer Lebertransplantate mittels normothermer Maschinenperfusion zu entwickeln. Material und Methoden: Eine nicht-alkoholinduzierte Fettleber wurde im Kleintiermodell durch Fütterung von Sprague Dawley-Ratten mit einer dreiwöchigen Hochfettdiät induziert. Die Lebern wurden anschließend explantiert und in einer miniaturisierten Perfusionsmaschine über drei Stunden perfundiert. Für eine pharmakologische Konditionierung wurde der mTOR-Inhibitor Everolimus (5-50 ng/ml) eingesetzt. Die Perfusionsleistung des Organs wurde mittels Blutgasanalyse und Untersuchung diverser Laborparameter evaluiert. Im Anschluss an die Versuche wurde eine histologische und elektronenmikroskopische Auswertung sowie eine photometrische Triglyceridanalyse des Gewebes durchgeführt. Ergebnisse: Das Modell einer nicht-alkoholinduzierten Fettleber im Kleintier mit einer gemischt- bis makrovesikulären Steatosis von über 30 % konnte erfolgreich etabliert werden. Die Perfusionsdrücke und Blutgasanalysen während ex vivo Maschinenperfusion zeigten annähernd physiologische Werte. Die Gruppe mit der höchsten Everolimus-Konzentration von 50 ng/ml erreichte im Vergleich zur Kontroll-Gruppe signifikant niedrigere Werte des Schädigungsparameters Aspartat-Aminotransferase und verbesserte Werte des Syntheseparameters Harnstoff. Eine Reduktion des Fettgehalts konnte in keiner der Gruppen, weder in den histologischen noch in den photometrischen Auswertungen, festgestellt werden. Schlussfolgerung: Das Ergebnis der Perfusion steatotischer Rattenlebern kann durch die Gabe von 50 ng/ml Everolimus signifikant verbessert werden. Eine Fettreduktion nach drei Stunden Perfusion war nicht zu beobachten, jedoch geben die Ergebnisse Anlass zu weiteren experimentellen Arbeiten mit beispielsweise einer längeren Versuchsdauer.Introduction: Liver transplantation is currently the only curative treatment option for patients with end-stage liver failure. Demographic changes and a growing prevalence of the metabolic syndrome increasingly lead to a lower organ quality. The transplantation of liver grafts with macrovesicular steatosis is associated with a significantly increased risk of graft failure. The aim of this work was to establish a pharmacological procedure for conditioning of steatotic liver grafts during normothermic ex-vivo liver machine perfusion in rats. Material and methods: A non-alcohol-induced fatty liver was induced in a small animal model by feeding Sprague Dawley rats a three-week high-fat diet. The livers were then retrieved and perfused in a miniaturized ex-vivo liver perfusion machine for three hours. For pharmacological conditioning, the influence of the mTOR inhibitor everolimus was investigated. The perfusion performance of the organ was evaluated by blood gas analysis and laboratory tests. Following the experiments, histological and electron microscopic evaluation and photometric triglyceride analysis of the tissue was performed. Results: The model of a non-alcohol-induced fatty liver in small animals with a mixed to macrovesicular steatosis of more than 30% was successfully established. Perfusion pressures and blood gas parameters were almost in a physiological range during ex vivo machine perfusion. The group with the highest Everolimus concentration of 50 ng/ml showed significantly lower values of the damage parameter aspartate aminotransferase while the synthesis parameter urea had improved compared to the control group. A reduction in fat content could not be detected in any of the groups, neither by histological nor photometric evaluation. Conclusion: The perfusion outcome of steatotic rat livers was significantly improved by the administration of 50 ng/ml Everolimus. Although no reduction of the fat content could be achieved after three hours of perfusion these results give rise to further experimental work with, for example, a longer test duration