Ex-vivo liver xenoperfusion for the treatment of acute liver failure

• Applicants: Dr. Wolf Ramackers; Professor Dr. Florian Vondran
• Subject Area: General and Visceral Surgery
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 505136093

Acute liver failure is a critical medical condition associated with considerable morbidity and mortality since therapeutic options are scarce. Allogeneic liver transplantation is the most commonly and widely used treatment for these patients, but success is often restricted due to the lack of suitable donor organs and the poor clinical condition of the recipients. Ex-vivo liver xenoperfusion represents a promising therapeutic approach in patients suffering from acute liver failure – especially due to the advantage of unlimited availability of appropriate organs. Although the clinical problems associated with this treatment strategy are almost similar to those known after xenogeneic liver transplantation (e.g. humoral rejection, coagulopathy, blood cell sequestration), there are important differences: The patient´s liver remains in place with the opportunity for organ recovery and the porcine liver can provide hepatic function without the risk of a demanding surgical intervention. The use of genetically modified livers should help to overcome or significantly lower the (immunological) barriers to allow sufficient organ function during xenogeneic extracorporeal liver perfusion, eventually enabling recovery of the patient´s liver (bridge-to-recovery) or as bridge-to-transplantation.This project aims to optimize ex-vivo liver xenoperfusion for the treatment of acute liver failure. A clinically feasible perfusion protocol will be established by setting up an ex-vivo perfusion circuit using porcine livers with targeted intervention by knock-out of porcine key genes regarding xenoreactivity and introduction of human genes in combination with an anti-inflammatory adsorber-based intervention. For this, perfusions with whole blood of porcine and human origin will be performed for autologous and xenogeneic control experiments, respectively. Blood samples will be obtained from the perfusion circuit at defined time points to determine the liver´s detoxification and synthesis potential, the coagulatory state as well as the state of immune activation. Additionally, histopathological and immunohistochemical analyses as well as real-time quantitative PCR for assessment of immunoglobulin deposits, complement components and markers of endothelial activation, will be performed using tissue samples. General functional parameters of the liver will be recorded during perfusion (i.e. arterial and portovenous perfusion, vascular resistance, bile production and organ survival). To identify the optimal genetic modification, perfusion experiments will be carried out in different experimental settings. Finally, the best overall combination of knock-outs will be combined with multiple transgenes.

• DFG Programme: Research Grants