An integrated perfusion machine preserves injured human livers for 1 week

Abstract

tandard preservation of donor livers is performed by flushing the organ with a cold solution at the time of procurement, which is followed by static storage on ice. This approach reduces liver metabolic activity, allowing safe storage for up to 12-18 h (refs. 1,2). Recently, the combination of supercooling with subzero storage (−4 °C) and hypothermic, as well as subnormothermic, machine perfusion achieved an extension of the preservation time of human livers up to 27 h (ref. 2). By contrast, human livers can also be kept metabolically fully active for up to 24 h by supplying normothermic blood or oxygenated fluids in a controlled environment by machine perfusion 1,3-5. The possibility of repairing poor-quality livers sufficiently to enable transplantation requires preserving metabolically active livers 1,3 for several days. Accordingly, the need for long-term organ preservation technology has been endorsed by multiple private and governmental initiatives 1. However, currently used normothermic machine perfusion technologies have been used only for a relatively short time period (for example, a median perfusion time of 9 h (ref. 5)), to successfully maintain hemodynamics, perfusate oxygenation and temperature. We sought to extend perfusion time beyond 24 h by engineering a perfusion machine that recapitulates additional core body functions that are critical to liver health. We chose 7-d as a target because this time period has been shown to offer a credible time frame for inducing clinically relevant liver regeneration in patients undergoing complex liver resection 6-8. Under physiologic conditions, the liver, which constitutes 2.5% of body weight, receives 25% of the blood output of the heart and performs >5,000 functions 9. It has a unique dual vascular supply with high-pressure, oxygen-rich arterial blood entering through the hepatic artery and low-pressure, oxygen-reduced portal vein blood draining the abdominal viscera. Its high metabolic activity produces waste products that are excreted in the bile or removed by hepatic macrophages or the kidneys. The metabolic profile is largely controlled by pancreatic hormones, including insulin and glucagon. Our perfusion technology, developed in the "Liver4Life project", includes automated control of glucose levels by injection of insulin and glucagon, a dialysis membrane for waste-product removal, regulation of oxygenation and liver movement to prevent pressure necrosis. Results Liver perfusion machine. Our perfusion machine (Fig. 1a,b) recapitulates blood supply through the two vascular entries of the liver, the hepatic artery and portal vein. The hepatic artery is supplied with oxygen-rich blood at elevated pressure (mean arterial pressure (MAP) ≥ 65 mmHg) in a pulsatile manner (Fig. 1c), whereas the portal vein receives blood at low pressure (around 5-10 mmHg) with a reduced oxygen content (venous blood, non-pulsatile). The system maintains oxygen saturation of 65% in the vena cava by continuously adjusting oxygen content in the portal vein (Fig. 1d). In vivo, nutr...

Ischemia-Reperfusion Injury in Marginal Liver Grafts and the Role of Hypothermic Machine Perfusion: Molecular Mechanisms and Clinical Implications

“…Notably, the cold storage control group achieved a 96% one-year survival rate [55,56]. A development in the NMP technique that allowed a 7-day preservation of human livers with sustained metabolic function and intact liver structure was recently reported by Eshmuminov et al [57]. Based on the sustained full hepatic metabolism during NMP, several groups are currently exploring the possibility of normothermic viability testing [58].…”

“…Pushing the boundaries and exploring the potentials of MP technology-such as the seven-day perfusion of human livers with preserved function and intact liver structure [57]-raise the question of the limits of this technological development. The enthusiasm for MP has to be viewed in the context of the limitations of the current technologies, which need to be defined clearly and early enough through clinical and translational efforts.…”

Bile Composition as a Diagnostic and Prognostic Tool in Liver Transplantation

“…(49) The recently published study by Eshmuminov et al shows that the majority of livers can maintain bile production during 7-day NMP stimulated by ursodeoxycholic acid infusion. (50) Whether or not infusion of bile acids also attenuates ischemia/reperfusion injury is still under investigation. (51,52) In a porcine LT model, it was shown that a lower bile/perfusate glucose ratio (<0.6) and a higher bile/ perfusate sodium ratio (≥1.2) during NMP was observed in DBD donors or donors with short warm ischemia (up to 70 minutes) compared with donors with long warm ischemia (120 minutes).…”

“…At the time of donor procurement ↑ PC Identify steatotic grafts (41) ↓ Choleretic activity Identify suboptimal grafts (10) ↓ CA/CDCA ratio Identify suboptimal grafts (34) During NMP HCO − 3 >18 mmol/L, pH >7.48, glucose <16 mmol/L, bile/perfusate glucose ratio <0.67, and LDH concentration <3689 U/L Predict low histological degree of bile duct injury (2) Bile production >10 mL and pH >7.45 Predict bile duct viability (14) pH <7.85 Predict NAS (16) pH <7.4 Predict NAS (53) After transplantation ↓ Na + and ↑ bile glucose-blood glucose Predict NAS (12) ↓↓↓ Lipids Identify PNF (24) ↑ CDmiR Predict ACR (26) ↑ miR-133a, miR-148a, and miR-194 Predict ACR (27,31,46,49,50) ↑ IL2, IL6, and IL8 Predict ACR (30)(31)(32) ↑ CXCL9/10 Predict ACR (27,33) ↓ Bile salt, phospholipids, and cholesterol during the first week after LT Predict NAS (35) ↑ Bile salt/phospholipid ratio during the first week after LT Predict histologically severe bile duct injury (37) ↑ miR-517a, miR-106a, and miR-892a…”

Kidney Perfusion as an Organ Quality Assessment Tool—Are We Counting Our Chickens Before They Have Hatched?

“…As the inflammatory cascade takes changes over time and stretches from minutes to hours and day, prolonged perfusion could be valuable. In that light, it is worthwhile to mention that 24-hour perfusion of discarded kidneys has been described [55], and recently, discarded human livers have been sustained ex situ for one week on normothermic perfusion [139].…”