Supercooling extends preservation time of human livers

Abstract

The inability to preserve vascular organs beyond several hours contributes to the scarcity of organs for transplantation 1,2. Standard hypothermic preservation at +4°C 1,3 limits liver preservation to less than 12 hours. Our group previously showed that supercooled ice free storage at −6°C can extend viable preservation of rat livers 4,5 However, scaling supercooling preservation to human organs is intrinsically limited because of volume-dependent stochastic ice formation. Here, we describe an improved supercooling protocol that averts freezing of human livers by minimizing favourable sites of ice nucleation and homogeneous preconditioning with protective agents during machine perfusion. We show that human livers can be stored at −4°C with supercooling followed by subnormothermic machine perfusion, effectively extending the ex vivo life of the organ by 27 hours. We show that viability of livers before and after supercooling is unchanged, and that after supercooling livers can withstand the stress of simulated transplantation by ex vivo normothermic reperfusion with blood. The absence of technology to preserve organs for more than a few hours is one of the fundamental causes of the donor organ shortage crisis 1-3. Subzero preservation has the potential to extend the organ storage limits 1-5 , as the metabolic rate halves for every 10°C Users may view, print, copy, and download text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use:

The Freeze-Drying of Foods—The Characteristic of the Process Course and the Effect of Its Parameters on the Physical Properties of Food Materials

“…The supercooling state can be achieved by various methods, e.g., by adding cryoprotectants [ 37 ], thanks to the external magnetic field that prevents the movement of water molecules to the crystal surface [ 38 , 39 ]. Another way is freezing at elevated pressure [ 40 ].…”

Organ Restoration With Normothermic Machine Perfusion and Immune Reaction

“…This technique could extend up to 27 h of ex vivo preservation of the liver, without altering the viability of the organ. In super-cooling livers, the parenchyma can withstand the stress of simulated transplantation by ex vivo normothermic reperfusion with blood (69). The results have shown some promising clinical outcomes (70,71).…”

Machine Perfusion: Cold versus Warm, versus Neither. Update on Clinical Trials

“…However, such strategies are still in the experimental stage. [16][17][18] While HMP can be performed with or without active oxygenation, NMP always requires oxygenation. Other protocol variations include the perfusion route (through the hepatic artery, portal vein, or both vessels) and the number and kind of pumps (pulsatile vs. nonpulsatile) or via gravitational force like the portal vein perfusion in the OrganOx metra (OrganOx Limited) device.…”