Molecular and proteomic signatures associated with preservation related graft injury: insight from human liver normothermic achine perfusion (NMP)

Fungai Dengu1; Sadr Shaheed1; Letizia Lo Faro1; Adam Thorne1; Honglei Huang1; Peter Friend1,Rutger Ploeg1. 1. Oxford Organ Perfusion Lab, Nuffield Department of Surgical Sciences and Oxford BiomedicalResearch Centre, University of Oxford, Oxford, UK BackgroundContinuous liver NMP is a novel technology associated with safe extension of organpreservation time, increased organ utilisation and reduced early graft injury1. Increasingly, it isutilised as a ‘back to base’ application with cold storage for organ transport and NMP initiatedat the implanting centre prior to transplantation2. We aimed to evaluate the impact ofadditional cold ischaemia time (CIT) on the proteomic and molecular signature of NMP livers. MethodsLiver tissue samples (N= 57) from a prospective clinical trial of ‘back to base’ NMP wereanalysed. Collection occurred at the end of cold storage (LT1), end of NMP/total preservation(LT2) and after organ reperfusion (LT3). Unbiased, label-free-quantitative (LFQ) proteomicanalysis was conducted using liquid chromatography with tandem mass spectrometry andtrapped ion mobility spectrometry (TIMS) to time-of-flight (TOF) mass analysis (LC-MS/MS TIMSTOF).Differential expression and Gene Ontology/Pathway analysis were performed. ResultsLT2 samples with prolonged CIT (>6hr) prior to NMP had significant differential expression ofproteins associated with liver-specific oxidative stress, cellular haemostasis and removal ofdamaged or misfolded proteins (e.g. CYP3A5, PSMB1). LT3 samples, similarly, had reducedproteins involved in autophagy and cell-cycle regulation (e.g. STBD1, CD2AP, GADD45GIP1,) andincreased expression of proteins involved in neutrophil chemotaxis, adhesion and aggregation(e.g. S100A9). DiscussionThe molecular signature of grafts at LT2 and LT3 varies depending on the length of CIT prior toNMP. Further exploration of the molecular signatures associated with preservation related graftinjury is required to determine how best to apply this novel technology clinically.   References:1. Nasralla, D. et al. A randomized trial of normothermic preservation in livertransplantation. Nature 557, 50–56 (2018).2. Ceresa, C. D. L. et al. Transient Cold Storage Prior to Normothermic Liver Perfusion MayFacilitate Adoption of a Novel Technology. Liver Transplant. lt.25584 (2019).doi:10.1002/lt.25584