Prof. Dr. Nathanael Raschzok received a grant of € 1.85 million for the first three years from the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) for the Pilot, open, prospective, randomized, multicenter trial on expanding the donor pool by quality assessment of liver grafts declined for transplantation by normothermic ex vivo liver perfusion – ExTra. Co-applicants and/or significantly involved in the preparation of the study were Prof. Dr. Johann Pratschke, Prof. Dr. Igor M. Sauer, Prof. Dr. Dominik Modest, and Priv.-Doz. Dr. Simon Moosburner.

Liver transplantation in Germany is severely limited by a critical shortage of acceptable grafts and a high mortality rate on the waiting list. Furthermore, a significant number of organs are declined due to quality concerns. As demonstrated in pilot studies in the UK, Netherlands, Australia, and the United States, declined liver grafts can and should be used for transplantation after quality assessment by normothermic ex vivo liver machine perfusion (NMP).

The ExTra trial is a randomized controlled trial with a specific focus on patients with a model for end-stage liver disease (MELD) score ≤25 that are not eligible for (non)standard MELD exceptions. This cohort of patients faces an unacceptably long wait time for transplantation, which increases their mortality risk while on the waitlist. The ExTra trial aims to demonstrate that the time-to-transplant for these patients is shortened through the use of grafts that were initially declined for transplantation but fulfill specified quality criteria on normothermic ex vivo machine perfusion assessment. A total of 186 patients will be randomized in a 1:1 fashion to the experimental arm, which consists of a 12-month option to receive a liver graft that was declined by all German transplant centers but meets specified quality criteria, in addition to listing for liver transplantation through the standard allocation process. The control arm will consist of patients who are waitlisted for liver transplantation through the standard allocation process. Liver grafts that have been declined for transplantation must meet specific quality criteria. These include a maximum of 60% macrovesicular steatosis, no fibrosis greater than stage F3, and no cirrhosis. In line with previously published viability criteria for initially declined liver grafts, the decision to use or decline the graft will be made at least four hours after the start of perfusion.

The ExTra trial aims to show that by expanding the donor pool to include the ExTra option of non-transplantable organs, which appear to be usable after machine perfusion, patients without a high MELD score can be transplanted significantly faster. The ExTra trial is thus the first study worldwide in which this concept will be investigated in a randomized clinical trial. The study should make an important contribution to expanding the donor pool for liver transplants and thus ultimately help all patients on the waiting list for liver transplantation.

How artificial intelligence supports surgeons: Planning surgical procedures, monitoring patients or predicting complications: there are already many useful applications for AI in the operating theater in research. In hospitals, the technology is still an exception. This is likely to change soon.
A Deutschlandfunk radio show/podcast by Carina Schroeder and Friederike Walch-Nasseri reports on the work in our Digital Surgery Lab (in German).
 
Artificial intelligence is revolutionizing our everyday lives. It translates texts, filters news, analyzes X-ray images and decides who gets a job. In the “KI verstehen (Understanding AI)” podcast, Deutschlandfunk provides answers to questions about dealing with AI every week.

The paper "Induced pluripotent stem cell (iPSC) line (EXSURGi001-A) from a patient homozygous for the p.Ala165Thr mutation in the MTARC1 gene" in Stem Cell Research is available open access. Authors are Peter Tang, Eriselda Keshi, Silvana Wilken, Louise Wutsdorff, Julienne Mougnekabol, Johann Pratschke, Igor M. Sauer and Nils Haep.

Metabolic dysfunction-associated fatty liver disease (MAFLD), the leading cause of end-stage liver disease in developed countries, is expected to increase over the next decade. Characterized by hepatic steatosis, MAFLD is commonly studied in animal models.
Here, we generated a human induced pluripotent stem cell (iPSC) line from a patient homozygous of the protective MTARC1 gene variant rs2642438:A.
This line displays a normal karyotype and typical pluripotent stem cell morphology and can differentiate into all three germ layers in vitro.

Our paper on "Viscoelastic properties of colorectal liver metastases reflect the tumour cell viability" has been accepted for publication in Journal of Translational Medicine.

Colorectal cancer is one of the third most common cancers in the world and up to 50% of the patients develop liver metastases (CRLM) within five years. To improve and personalize therapeutic strategies, new diagnostic tools are urgently needed. An improvement could be achieved by considering biomechanical tumour properties with the implementation of magnetic resonance elastography (MRE). Our main hypothesis is that ex vivo MRE combined with histological evaluation of CRLM could provide the knowledge for using tissue mechanical properties as a diagnostic marker for cell viability in tumours.

We examined 34 CRLM samples from patients who had undergone liver resection at the Charité – Universitätsmedizin Berlin, Department of Surgery. The samples were investigated with an ex vivo MRE.  We employed a frequency range from 500 Hz to 5300 Hz, with increments of 400 Hz. For histological analysis, the samples were stained with H&E for categorization by a board-certified pathologist based on their grade of regression. The radiological response was evaluated using the RECIST-criteria.

Five samples showed major response to chemotherapy, 6 samples partial response, and 23 samples showed no response. Analysis of shear wave speed c significant correlation for frequencies including 2100 Hz and above depending on the grade of regression, indicating that low cell viability in CRLM is associated with higher tumour stiffness. Analysis of frequency-independent values of the SP-model showed a more elastic-solid behaviour at low cell viability. Our results suggest that MRE can be used to characterize the biomechanical properties associated with cell viability in CRLM, showing a higher stiffness and elastic-solid behaviour with high regression. In the future, MRE could help to improve the diagnostic tools to create an individual, tailored therapy plan for patients with CRLM.

Authors are Lisa-Marie Skrip, Simon Moosburner, Peter Tang, Jing Guo, Steffen Görner, Heiko Tzschätzsch, Clarissa Hosse, Uli Fehrenbach, Alexander Arnold, Dominik Modest, Felix Krenzien, Wenzel Schöning, Thomas Malinka, Johann Pratschke, Björn Papke, Josef A. Käs, Ingolf Sack, Igor M. Sauer, and Karl H. Hillebrandt,

Our systematic review on "Thrombogenicity assessment of perfusable tissue engineered constructs" has been accepted for publication in Tissue Engineering, Part B, and is available online ahead of print.

Vascular surgery faces a critical demand for novel vascular grafts that are biocompatible and thromboresistant. This urgency particularly applies to bypass operations involving small caliber vessels. In the realm of tissue engineering, the development of fully vascularized organs holds great promise as a solution to organ shortage for transplantation. To achieve this, it is imperative to (re-)construct a biocompatible and non-thrombogenic vascular network within these organs. In this systematic review, we identify, classify and discuss basic principles and methods used to perform in vitro/ex vivo dynamic thrombogenicity testing of perfusable tissue engineered organs and tissues. We conducted a pre-registered systematic review of studies published in the last 23 years according to PRISMA-P Guidelines, comprising a systematic data extraction, in-depth analysis and risk of bias assessment of 116 included studies. We identified shaking (n=28), flow loop (n=17), ex vivo (arterio-venous shunt, n=33) and dynamic in vitro models (n=38) as main approaches for thrombogenicity assessment. This comprehensive review unveils a prevalent lack of standardization and serves as a valuable guide in the design of standardized experimental setups.

Authors are Luna M. Haderer, Yijun Zhou, Peter Tang, Assal Daneshgar, Brigitta Globke, Felix Krenzien, Anja Reutzel-Selke, Marie Weinhart, Johann Pratschke, Igor M. Sauer, Karl H. Hillebrandt, and Eriselda Keshi.