Long-Term Ex Situ Normothermic Kidney Perfusion

Abstract Background Marginal grafts are increasingly considered for transplantation due to the widening gap of available donor grafts and waiting recipients. Graft assessment and repair prior to implantation are therefore essential to minimize the risk of failure. Normothermic perfusion has not been widely evaluated for kidney grafts, with existing perfusions limited to 2 days. Aims The aim of this study was to develop a long-term (>3 days) normothermic ex situ swine perfusion model in kidney grafts, while maintaining organ viability. We also wanted to investigate possible regenerative processes of the kidney during this period outside the donor animal. Methods Swine kidneys were retrieved with minimal injury. After cannulation, organs were perfused at 37°C for up to several days in a newly designed normothermic ex situ device with automated blood gas and glucose regulation, addition of nutrition, antibiotics, and vasodilators. Kidney biopsies, urine and perfusate samples were taken daily for analysis as well as markers of viability. Results In total 17 kidneys were perfused. Four kidneys were perfused for 3 or more days. Viability was maintained up to 4 days without histological evidence of glomerular and minimal to moderate tubular necrosis. We observed upregulation of ki67 and pH3 in tubular cells with mean values of up to 14.2% and 2.2% respectively. This expression of ki67, a proliferation associated protein, correlated with the duration of ex situ perfusion. Conclusion This is the first report of normothermic kidney perfusion for up to 4 days with unprecedented observation of upregulated ki67 and pH3 after multiple days of perfusion. These preclinical results open the door for development of long-term perfusion protocols for discarded human grafts while also hinting at limitations and challenges.