Scientists have succeeded for the first time in cryogenically freezing and rewarming sections of heart tissue without causing damage.
If the technique can be used for entire organs, and scientists are predicting it will, it could be a lifesaver for patients who die each year waiting for transplants.
In Ireland last year, 15 heart transplants and 35 lung transplants were carried out, figures that compare well with those for 2015 when there were 16 heart transplants and 36 lung transplants.
Scientists in the United States, whose work is published in Science Translational Medicine, were able to rapidly rewarm large tissue samples by infusing them with magnetic nanoparticles.
Currently, donor organs such as heart, livers and kidneys must be transplanted within hours because the cells begin to die when the organs are cut off from a blood supply.
The minimum tolerable organ preservation for transplantation by hypothermic (chilled) storage is around four hours for heart and lungs, eight to 12 for liver, intestine and pancreas, and up to 36 for kidneys.
Unfortunately, advances in tissue and organ cooling for cryopreservation have not been matched by similar advances in rewarming.
Cryopreservation works well for red blood cells, sperm and eggs but scientists have not had the same success with larger samples.
The big problem is the thawing process. Unless the rewarming is rapid and uniform, fractures and cracks will appear.
The research team at the University of Minnesota believe it will be possible to apply nano warming to tissues and organs up to volumes of one litre and possibly beyond.
Consultant cardiothoracic surgeon at the Mater and Crumlin Hospitals in Dublin, Lars Nolke, said the cryogenics breakthrough was “fantastic”.
As well as performing heart and lung transplants, Mr Nolke is also director of the Irish Heart and Valve Bank at the Mater Hospital.
“We take valves from patients who had transplants. When their hearts come out, we retrieve their valves and freeze them using liquid nitrogen. The valves can remain frozen for up to five years.”
However, Mr Nolke believes that it could take some years before it would be possible to cryogenically freeze and rewarm organs for transplantation.
There would also be the challenge of getting the organ cooled, protected and keeping everything viable before cryopreservation.
“It would be fantastic, but I think it is likely that the process would be very expensive,” he said.
Mr Nolke believes that preserving organs by cryopreservation would allow organs from less common blood group donors to be stored until there was a suitable recipient.