Molecular Targets of Preservation Injury Mitigated by Hypothermic Oxygenated Machine Perfusion in Liver Transplantation

PROJECT SUMMARY Liver transplantation (LT) is the only definitive cure for end stage liver disease; however, there is a growing gap between organ demand and availability. This has led centers to rely on extended criteria donors (ECD), which include grafts from older donors, fattier livers, or following donation after cardiac death (DCD). These grafts are particularly vulnerable to preservation injury and carry increased risk of post-LT complications. Optimizing organ preservation techniques would improve patient outcomes, increase utilization of ECD grafts, and improve access to life-saving LT. Hypothermic Oxygenated Machine Perfusion (HMP-O2) provides continuous liver flush with oxygenated preservation solution. HMP-O2 shows great promise in early clinical trials in the US and Europe. Recipients exhibit decreased preservation injury and improved early post-LT outcomes. The exact molecular pathways modulated by HMP-O2 remain largely undefined. Our team has pioneered machine perfusion in LT. With a novel portable perfusion pump, the LifePort® Liver Transporter (LLT, Organ Recovery Systems), we are the lead institution in the first US prospective, randomized controlled multi-center trial comparing HMP-O2 vs Static Cold Storage (SCS, conventional storage on ice) in LT (NCT 03484455). Under the continued access phase, with non-randomized enrollment of patients, we have increased utilization of ECD grafts at our center with excellent outcomes. To characterize the molecular targets of early allograft injury, we have paired this with an extensive longitudinal bio-specimen collection protocol. The long-term goals of the present research are to (1) define the protective pathways activated by HMP-O2 compared to SCS and (2) to identify target biomarkers for organ monitoring and for future therapeutic optimization of allograft function. Initial data from our center show HMP-O2 improves post-LT morbidity. Preliminary biochemical, molecular, and tissue injury analyses demonstrate improved tissue structural integrity, decreased inflammatory signaling, and preserved cellular function. We hypothesize that HMP-O2 improves early allograft function and risk of post-operative complications by decreasing inflammatory signaling, moderating cellular metabolic dysregulation, and ultimately, promoting cellular homeostasis. Specific aims are proposed to (1) immune cell activation, inflammatory signaling, and metabolic dysfunction mitigated by HMP-O2, as well correlate proteogenomic markers of preservation injury between tissue and liver perfusate in HMP-O2 define as to (2) compared to SCS to establish thresholds of irreversible injury for ex vivo monitoring. Capitalizing on our extensive biorepository, histologic, biochemical, genetic, and protein markers of injury will be defined in tissue (liver and bile duct), preservation fluid effluent, and bile. We expect to see decreased markers of inflammation, abrogated cell injury, and increased homeostasis during and following HMP-O2 compared to SCS. These studies are critical to identify molecular targets to improve pre-LT organ monitoring, facilitate earlier recognition of graft injury, optimize liver graft utilization, and increase access to life-saving LT.