Scientists successfully freeze and rewarm heart tissue

2nd March 2017

Scientists in America have successfully frozen and rewarmed pig heart tissue for the first time, raising hopes it may eventually enable banks of human hearts to be kept for transplant.

If the technique can be used for entire organs it could save the lives of thousands of people who die each year waiting for a heart transplant, the team says.

The work is being seen as a major development in the field of cryogenics. It is the first time large tissue samples have been frozen and thawed without them shattering, cracking or turning to a pulp.

The US team overcame these problems by infusing the pig heart tissue with magnetic nanoparticles, which could be excited in a magnetic field, generating a rapid and uniform burst of heat. The scientists now plan to use the technique on skin, muscle and blood vessels from human donors.

Kelvin Brockbank, chief executive officer of Tissue Testing Technologies in Charleston, South Carolina and a co-author of the study, said: “It is a huge landmark. We can see the road ahead for clinical use and getting tissues and organs banked and into patients.”

Currently, donor organs including hearts have to be transplanted quickly as their cells begin to die as soon as they are cut off from a blood supply. As a result, many hearts donated for transplantation are unused each year.

Recent estimates suggest that if these hearts could be saved, transplant waiting lists could be eliminated within two to three years.

While freezing and thawing has worked well for red blood cells, sperm and eggs for many years, scientists have previously had problems thawing larger amounts of tissue.

Unless rewarming can be rapid and uniform, tiny ice crystals suddenly expand, destroying cell structures.

John Bischof, professor of mechanical engineering at the University of Minnesota and the senior author of the study, said: “We have extremely promising results."

In the journal Science Translational Medicine, the team describes the new “nano-warming” technique which they used on pig heart valves and blood vessels.

The researchers said the tissues did not show any signs of harm and  they were also able to successfully wash away the iron oxide nanoparticles from the sample following the warming.

NHS statistics show that thousands of people in Britain,including some with cardiomyopathy, have had to wait for an organ transplant in the past decade and more than 6,000, including 270 children, have died before receiving the transplant they needed.