Subzero organ preservation: the dawn of a new ice age?

Abstract

Purpose of review: Herein, we review the field of subzero organ preservation with a focus on recent developments in hepatic supercooling.

Recent findings: Organ preservation is making a rapid shift from the decade old standard of storage on ice toward techniques that improve organ availability as well as preservation time. Long-term organ preservation would have tremendous benefits to the organ transplantation field, including better organ allocation, donor-recipient matching, as well as reduced preservation injury, and subsequent improvement of donor organ use. The formation of ice has proven an important limiting factor and novel techniques attempt to control or prevent freezing using cryoprotective agents, and highly controlled cooling regimens. Various techniques have been employed over the previous decades, including true organ freezing, vitrification, and subzero nonfreezing or supercooling. For most techniques, successful transplantation following long-term subzero preservation has remained elusive. Supercooling, however, recently delivered the first promising results, yielding survival after up to 4 days of supercooled preservation at -6°C.

Summary: As the field of organ preservation undergoes significant development, the field of subzero preservation also receives renewed interest. Although many obstacles remain to be overcome to make subzero preservation feasible, novel techniques are beginning to show their potential in achieving long-term preservation.

Fig. 1. Pre-supercooling liver perfusion set up

Rat livers are perfused for 60 minutes in a subnormothermic machine perfusion (SNMP) system to load the organ with cryoprotectants.