Figure 1. Liver preservation protocol. The liver preservation protocol reported by Berendsen et al. combined subnormothermic machine perfusion (SNMP) with supercooling and enabled rat livers to be cryopreserved for up to four days prior to successful transplant.

The protocol included three major steps; loading, supercooling and recovery. Prior to supercooling, livers were loaded by SNMP with cryopreservation medium that was supplemented with 3-O-methyl-d-glucose. During loading, livers were cooled to 4 °C at a rate of 1 °C per minute. After loading, the livers were flushed with UW solution containing 5% 35 kDa polyethylene glycol and submerged in the same solution.

For supercooling, livers were placed inside a controlled-rate freezer and cooled to -6 °C at a rate of 0.1 °C per minute. The supercooling phase was maintained for 72 or 96 hours.

To recover the livers for transplant, the temperature was gradually increased to 4 °C when livers were flushed with medium and subjected to SNMP for 3 hours. Livers were transplanted into healthy syngeneic rats. (Figure based on Figure 1a in ref. 1.)