Preclinical validation of a customized circuit for ex situ uninterrupted cold‐to‐warm prolonged perfusion of the liver

Context Clinical adoption of ex situ liver perfusion is growing. While hypothermic perfusion protects against ischemia–reperfusion injury in marginal grafts, normothermic perfusion enables organ viability assessment and therefore selection of borderline grafts. The combination of hypothermic and normothermic perfusion, known as “cold‐to‐warm,” may be the optimal sequence for organ preservation, but is difficult to achieve with most commercial perfusion systems. We developed an adaptable customized circuit allowing uninterrupted “cold‐to‐warm” perfusion and conducted preclinical studies on healthy porcine livers and discarded human livers to demonstrate the circuit's efficacy. Methods In collaboration with bioengineers, we developed a customized circuit that adapts to extracorporeal circulation consoles used in cardiovascular surgery and includes a proprietary reservoir enabling easy perfusate change without interrupting perfusion. This preclinical study was conducted on porcine and human livers. Perfusion parameters (pressures, flows, oxygenation) and organ viability were monitored. Results The customized circuit was adapted to a LivaNova S5® console, and the perfusions were flow‐driven with real‐time pressure monitoring. Ten porcine liver and 12 discarded human liver perfusions were performed during 14 to 18 h and 7 to 25 h, respectively. No hyperpressure was observed (porcine and human portal pressure 2–6 and 2–8 mm Hg; arterial pressure 10–65 and 20–65 mm Hg, respectively). No severe histological tissue injury was observed (Suzuki score ≤ 3 at the end of perfusion). Seven (70%) porcine livers and five (42%) human livers met the UK viability criteria. Conclusion The customized circuit and system design enables smooth uninterrupted “cold‐to‐warm” perfusion not present in current commercial perfusion systems. This customized circuit, adapted from an extracorporeal circulation circuit, allows for an easy combination of hypothermic and normothermic perfusion on the same perfusion. There is no interruption of oxygenated perfusion during the change from preservation solution to whole blood. Perfusion results from discarded porcine and human livers have demonstrated a reliable and effective system.