Doctors aim to transplant hearts within four hours of donation
Doctors currently aim to transplant hearts within four hours of donation, before tissue begins to die. But the revolutionary new system could increase the time they remain viable six-fold. Small enough to fit into carry-on luggage, it could even allow hearts to be flown across the globe to provide the best possible match.
The ULiSSES device was developed over 30 years by researchers at the University of Texas and biotech company Vascular Perfusion Solutions.
To mimic the conditions of the body, the heart is stored in a small cylinder and supplied with oxygen-rich fluid kept at around 4C.
The perfusion liquid is widely available in hospitals and consists of salt water with added sodium, potassium and glucose, among other things.
Senior researcher Dr Rafael Veraza, from UT Health San Antonio, said: “The first heart was transported more than 50 years ago by putting it on ice, and decades later it is done much the same way.
It could even allow hearts to be flown across the globe to provide the best possible match
“Donor hearts are being wasted because they are unable to reach a recipient in time and people are dying waiting for a transplant.
“The machine is a game-changer and has the potential to save thousands of lives.”
Donor organs are traditionally transported in ice chests and cooled to slow deterioration.
However, almost three quarters of hearts donated after brain stem death are not accepted for transplantation.
More than 300 people are on the waiting list for a heart transplant in the UK and the average wait is 1,085 days – almost three years.
Dr Veraza said: “Keeping a heart alive for 24 hours would allow doctors to transport it almost anywhere in the world to whoever needs it.
“Time is currently a major obstacle and limits where an organ can be used. ULiSSES overcomes that.”
The research was presented at the American Association for the Advancement of Science conference in Seattle yesterday.
During trials with five pig hearts – the closest animal model for human hearts – ULiSSES kept them healthy for an entire day.
It has also been used to successfully preserve and transplant a dog’s heart.
The researchers are now planning to transplant a pig heart stored in the device. If all goes well, human trials will be underway within a year.
More than 300 people are on the waiting list for a heart transplant in the UK
Dr Veraza said: “Donor hearts typically remain viable for around four hours using traditional preservation methods.
“But we have shown it may be possible to preserve them up to six times longer.
“The pig hearts in our trial appeared to remain viable 24 hours after they were harvested. The cells were healthy and functioning.
“Pig hearts are similar to human hearts, so we would expect the same result in human trials, which we hope to start shortly.”
The researchers expect the device to cost less than £100,000. It currently uses batteries, but they are confident it can be improved to run without a power source by harvesting energy from the expanding oxygen.
Dr Veraza and his colleagues will file their pre-application for FDA approval within a month.
They also hope to use the technology in warzones to preserve soldiers’ severed hands, arms and legs until they can be reattached.
COMMENT Dr Rafael Veraza, from UT Health San Antonio
I am from Mexico and I immigrated to the US many years ago. When I was an undergrad, I met a seven-year-old boy from Mexico who came to the US with cardiomyopathy.
He needed a $ 500,000 transplant and his family couldn’t afford it, so my friends and I at the university raised the money to make it possible.
That forever changed how I view medicine and public health, and I wanted to do research that would help people’s lives.
Through my PHD program I met my professor, Leonid Bunegin, who invented the ULiSSES™ device, and I started working with him in his lab.
A big part of our research focuses on the heart because there is no life without it, and there is a shortage of hearts.
In a perfect scenario you could transplant organs around the world, but in the US organ allocation is regional because of time constraints.
The current standard of care is between four to six hours for a heart placed on ice, but the longer a heart is on ice, the higher the risk that the organ will not make it to the patient in a condition suitable for transplant.
If you are able to take a heart and place it in a device that can preserve it, you will have more time to do tests to find a better match, and you are able to provide it for a patient further away.
We needed an animal model that can closely resemble a human. The closest one would be non-human primates – monkeys – but those are very expensive.
The second closest is the pig.
It’s an animal model that’s very close to humans.
In preliminary tests, we took five pig hearts and put them into the ULiSSES device, and we cooled it to emulate hypothermia.
After 24 hours we took samples and found that the cells remained intact, with very little cell death or inflammation.
Once we show this works really well in animals, we will move to human organs that are not suitable for transplantation – organs that would otherwise be discarded.
We are also working with the Department of Defense to adapt the device to recover severed limbs for possible reattachment.
As part of this testing we use animal limbs and lay them out for an hour or two outside the body to replicate what happens in war.
Then we put them into the device and start perfusing and we’re able to see that the muscle is being preserved.
We’ve also used it to preserve rat colons, where the histology shows that the tissue looks normal after 48 hours at room temperature.
Most devices are really big, expensive, and complicated. Our focus is to bring the world a device that is portable, affordable, and easy to use.
It’s exciting to work that we hope will impact many lives – not unlike the seven-year-old boy who inspired me all those years ago.
In the UK, the main reason hearts are not taken from donors is because they are unsuitable.
But John Forsythe, medical director for organ donation and transplantation at NHS Blood and Transplant, said improving the time between removing an organ and transplanting it is still “crucial”.
He said: “The use of machines to stabilise and preserve organs is one important area of development, and the use of oxygen ‘perfusion’ techniques has proven extremely successful in other organs, including liver and pancreas.
“UK teams are exploring the use of similar techniques for heart transplantation… We welcome any research that builds on this.
“With the current number of people waiting for hearts, significantly outweighing the number of suitable donor organs, it is vital that we continue to embrace all new research and techniques to improve the chances that these desperately ill patients will get the call they are waiting for.
“Every donor, and donor heart, is precious and we constantly strive to ensure that as many as possible are able to be successfully transplanted.”