Donated livers can survive for at least a day outside the body thanks to a new device which keeps the organ ticking over as if it hadn't been removed. The machine is likely to more than double the availability of livers for transplant.
The device was unveiled today in London by its developer Peter Friend, professor of transplantation surgery at the University of Oxford.
In the US and Europe, 2000 livers get discarded each year because they deteriorate in transit, damaged by the ice packs and solutions that, for the past 40 years, have been the usual way to preserve them. At present, a quarter of the 30,000 people on US and European liver transplant waiting lists die each year before receiving an organ.
The new device can keep a donated liver at body temperature, supplying it with blood, sugar, oxygen and nutrients.
Whereas most frozen livers become unusable after about 14 hours of cold storage, the new device keeps them alive and in perfect condition for at least 24 hours. "In animals, we've gone up to 72 hours and see no reason why it shouldn't go even further than that," says Friend.
Buying time
He is hopeful that as well as buying precious time in which to use the organ, the device will enable surgeons to better judge a liver's condition before transplanting it, because in the device, it carries on functioning as normal.
"It gives the opportunity to test-drive the organ before transplanting it," says Constantin Coussios, co-developer of the device and founder of OrganOx, the company set up by the University of Oxford to commercialise it.
Video footage shows Friend plumbing a donated liver into the device. Within seconds of connection, the brown-grey organ turns bright red as blood floods into its capillaries. As in the body, blood and nutrients enter through the hepatic artery and the portal vein, and exit through the inferior vena cava. A fourth connection to the bile duct enables the liver's functioning to be monitored.
The box containing the liver and its plumbing is connected to a master console that monitors and controls the organ's life support.
A pump mimics the heart, an oxygenator mimics the lungs and tubes supply donated blood, explains Stuart Kay of Team Consulting in Cambridge, UK, which miniaturised and optimised the original system developed at Oxford. "The key is that the system 'listens' to the organ to find out how much blood to supply, and at what pressure," says Kay.
Sensors for fluid flow and pressure, plus levels of oxygen, carbon dioxide and sugar in the blood, are part of the disposable circuitry, he adds. Also, the device is fully automated so that non-specialist medical staff can use it and load it easily into planes or ambulances.
Clinical pilot
Two people have received livers kept alive using the device. They were both treated at King's College Hospital, London, in February, and are among 20 people taking part in a pilot clinical trial that, if successful, should allow the device to win approval for use in Europe by next year.
Further randomised trials are planned to compare the performance of the device with existing preservation methods using freezing. Friend says that animal experiments, mainly in pigs, have already demonstrated that the device outperforms freezing. It also enables surgeons to transplant fatty livers that would normally be rejected because they do not respond well to the freezing process, he says.
Friend says that with modifications, the same technology could be applied to preserve the pancreas, kidneys, small bowel and lungs.
source: http://www.newscientist.com
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