Ex Vivo Normothermic Perfusion, a Novel Method to Assess Pancreases after Preservation

Abstract

Julien Branchereau1,2* and Etohan Ogbemudia1*, Kaithlyn Rozenberg1, Fungai Dengu1, Gabriella Hakim1, Flavia Neri1, Georg Ebeling1, Letizia Lo Faro1, James Hunter1, Rutger Ploeg1* and Peter Friend1* * "Authors contributed equally to this work" 1-Nuffield Department of Surgical Sciences - University of Oxford 2-Nantes Hospital University - France Introduction Static cold storage (SCS) of pancreases remains the current standard method for preservation prior to transplantation. Pulsatile hypothermic machine perfusion (HMP) is an emerging method that could potentially improve the preservation of pancreases to enhance graft function. This is based on personal extensive experience with HMP of pancreases in human, porcine allotransplantation and large non-human primate models. All models consistently showed preservation of pancreatic parenchyma on histological assessment for up to 24hours. To provide reassurance of organ viability prior to transplantation further investigations are necessary. We propose that normothermic perfusion (NMP) of pancreases after cold preservation allows necessary functional and physiological assessments. Method Porcine pancreases (3) were retrieved from the slaughterhouse after 30 minutes of warm ischaemia and were flushed. After 3 hours of cold ischaemia two pancreases were perfused by HMP (Wave machine; Waters Medical Systems) for 6 hours followed by 1 hour of NMP. One pancreas after 3 hours of CIT was placed on NMP for 2.5hours, this was the first pancreas NMP to assess feasibility of this technique.NMP was achieved by modification of the kidney assist device. Oxygenation was with 21% oxygen. The pancreases were cannulat ed via the aorta with free drainage of perfusate from the portal vein. NMP parameters for all pancreases were a pressure of 40mmHg and temperature of 37C. Perfusate was composed of red blood cells, plasma to provide a haematocrit of 25%, with additives of co-amoxiclav and 25,000IU of heparin. During the perfusions we collected serial perfusate samples for blood gas analysis and for insulin enzyme-linked immunosorbent assay (ELISA). Results The macroscopic appearance of the pancreases and the attached duodenum at the end of NMP appeared viable. Average resistance index during NMP was 0.62 ru (range 0.30 to 0.90 ru). Average flow rate was 77mls/min (range 53 to 100 mls/min). Throughout, the duration of NMP in the two pancreases perfused for one-hour lactate remain stable with no increase from baseline. In the one pancreas perfused for 2.5hours lactate was also stable in the first hour then increased by 50% during the last 1.5hours of perfusion. ELISA confirmed the presence of insulin in the perfusate for all three perfusions. Conclusion Normothermic perfusion is a feasible method to allow physiological and functional assessment of pancreases after cold preservation techniques encouraging us to further develop this model.