Kidneys can be preserved in ice, stored then rewarmed to be used efficiently for organ transplants, new research in rats has shown.

A study at the University of Minnesota, USA, found a way to cryogenically freeze (see photo) rat organs and thaw them quickly and evenly, which could improve the chances of patients receiving a viable organ.

Long-term preservation methods for organs are needed because one in five donated organs for transplants currently cannot be kept on ice for long enough (to keep them preserved) and do not reach patients in time.

The researchers tested this approach on rat kidneys, storing them for 100 days, and saw that when these kidneys were later transplanted into live rats, the animals’ full kidney function was restored and “completely indistinguishable from transplants of a fresh organ”, said Erik Finger at Minnesota.

The team will next investigate their approach in pig kidneys, which have larger organs more comparable to humans’.