195 Nitric oxide treatment during normothermic perfusion of the kidney – a pre-clinical study

Abstract Introduction Normothermic machine perfusion of the kidney (NMP-K) is a technique for ex-situ preservation, assessment, and treatment of kidneys prior to transplantation. We have previously reported a phase 1 trial (NKP1) showing that up to 24 hours of NMP-K appears to be safe, feasible, and that ex-situ NRF-2 modulation may be of benefit. Nitric oxide (NO) is a potent inducer of NRF2 and has been shown to halve the rate of acute kidney injury after cardiopulmonary bypass. We therefore sought to develop and test a paradigm for NO treatment during NMP-K. Methods Six pairs of porcine kidneys were retrieved and assigned at random to perfusion with NO administered at 40ppm via the oxygenator, or standard NMP-K. Five human kidneys deemed unsuitable for transplantation were perfused with a modified protocol involving treatment with NO, and co-administration of N-acetylcysteine and ascorbic acid. Comparisons were made to matched controls from NKP1. Results In the NKP1 cohort, IL-18 measured at hour 2 was associated with delayed graft function, and GST-Pi upregulation with good 12-month graft function. NO administration to porcine kidneys raised intracellular cGMP, enhanced GST-Pi, and suppressed IL-18. In discarded human kidneys, despite much longer cold ischaemia times than matched transplanted controls, GST-Pi appeared upregulated by NO treatment. Untargeted metabolomics (n=1) demonstrated replenishment of intracellular glutathione. However, IL-18 production was not suppressed. Discussion NO administration during NMP-K positively modulates ex-situ biomarkers. Pre-perfusion CIT has a profound effect on ex-situ assessment and treatment. NO delivery during NMP-K should be evaluated in a clinical trial.