Pig study offers hope for heart transplants

A PIONEERING technique for preserving pigs’ hearts for up to 24 hours outside the body could be a major step forward in increasing the number of human hearts available for transplant, say scientists.

Until now, human hearts taken for transplantation can only be preserved for around six hours.

But if the new technique can be replicated, it could extend the shelf life of a donated organ for at least a day.

More than 5,000 hearts are transplanted each year around the world. But the figure falls far short of global demand, with around 50,000 people waiting at any given time.

Depending on how ill they are, and other physiological and logistical factors, some candidates have to wait for years.

A bottleneck in the system is the availability of suitable hearts, partly due to the short time window for transplantation once the organ is removed from the deceased donor. The current gold standard for preserving donor hearts is cold static storage, where they are kept on ice until transplantation.

A transplant is most successful when storage lasts less than six hours, before the heart or its blood vessels suffer damage.

Periods of up to 12 hours are sometimes possible but require the recipient to be on mechanical life support for several days. A study published in Frontiers in Cardiovascular Medicine has shown it is possible to keep transplanted pig hearts alive outside the body for more than 24 hours.

“If we can translate this to humans, it would be a major improvement to the sixhour window in standard clinical practice,” said Dr Robert Bartlett, of the University of Michigan Medical School.

The process, called normothermic ex-vivo heart perfusion, sees the organ, once removed from their donor, kept in a partphysiological state at room temperature.

Oxygenated, nutrient-rich fluid derived from blood plasma is pumped through it.

Drugs and tissue-repairing stem cells can be delivered to the heart through the fluid.

The research team has now started to work with human hearts rejected for transplantation to test the new technique.