A portable miracle machine that breathes life into ailing livers outside the body could revolutionise organ transplants, experts believe.
Doctors believe the technology could be adapted to suit a range of other organs, other than the heart, including the pancreas, kidney, small bowel and lungs.
The British-built device, set on wheels and the size of a supermarket trolley, can keep a donor liver alive for 24 hours or more at body temperature.
As well as preserving the organ, it helps damaged tissue repair itself by delivering a carefully balanced combination of blood, oxygen and nutrients.
After the machine is switched on it takes less than a minute for a donor liver to come back to life, as it is pumped with blood and flushes back to colour.
Doctors believe the machine, which could be ready to market in Europe next year, has the potential to double the number of livers available for transplant.
In five years it could be replacing the current method of flushing an organ with preservative, cooling it to 4C (39.2F), and then racing to carry out the transplant before deterioration sets in.
Modified versions of the device may also assist transplants of other organs, including kidneys and lungs, and provide a tool for testing the toxicity of new medicines.
Two patients are said to be recovering well after taking part in a pilot trial to test the machine at London's King's College Hospital, Europe's biggest organ transplant centre.
Ian Christie, 62, from Torbay, Devon, the first person in the world to benefit from the technology, said: "I feel better than I've felt for 10 to 15 years, even allowing for the pain and wound that's got to heal. I'm getting better and better day by day."
Another female liver recipient has also delighted surgeons with her progress. Neither patient has suffered any complications.
To operate the machine, surgeons simply place the donor liver into a holding container, plug in tubes carrying blood and bile, and press a "start" button. The device then runs itself automatically, supplying the tissue with just the right balance of oxygen and nutrients.
In the pilot trial the device was used to preserve donor livers for just 10 hours. But experts from the Oxford University design team are confident they can keep organs functioning outside the human body for 24 hours, and pre-clinical tests suggest time periods of 72 hours or more may be possible.
Using the standard cooling technique, an "ideal" liver can be stored for a maximum of 20 hours, but in practice most surgeons dare not wait longer than 14. Every hour that passes causes the organ to suffer some degree of irreparable damage.
Professor Constantin Coussios, co-inventor of the machine and technical director of Oxford University spin-out company OrganOx, set up to commercialise the device, said:
"The device is the very first completely automated liver perfusion device of its kind: the organ is perfused with oxygenated red blood cells at normal body temperature, just as it would be inside the body, and can for example be observed making bile, which makes it an extraordinary feat of engineering.
"It was astounding to see an initially cold grey liver flushing with colour once hooked up to our machine and performing as it would within the body. What was even more amazing was to see the same liver transplanted into a patient who is now walking around."
No price tag has yet been set on the machine, but the team insists it will be "affordable".
Each year, 650 liver transplants are performed in the UK; however the demand for new organs far exceeds the supply. An estimated 8,000 patients are waiting for organs of different types.
Many organs are taken from older donors or have suffered some form of damage before being removed. The conventional cooling and perfusing process leads to further damage, especially in cases of "fatty liver", a condition affecting 30% of the population.
One great advantage of the new machine is that enables fatty livers to repair themselves, replacing damaged tissue with healthy cells. In contrast, the cooling technique causes fatty liver tissue to harden, resulting in a loss of liver function.
Allowing surgeons the opportunity to "test drive" a donor liver under natural conditions can also show up problems that might otherwise only appear after the transplant. Many donor livers conceal hidden injuries, and 15% of recipients suffer ongoing liver dysfunction.
Wayel Jassem, consultant liver transplant surgeon at King's College Hospital, who performed the transplants, said: "This is very exciting - potentially a major change in practice for liver transplantation.
"I think it's a breakthrough and it has the potential to take us into a new age."
Surgeons hope to perform 20 liver transplants in the pilot trial. A further 35 patients have given their consent to receive livers kept alive on the machine.
Preparations are also being made for a larger comparison trial at several centres throughout Europe, to take place within the next few months.
Around 300 patients are expected to take part, half of whom will be given livers preserved on the machine while the rest receive "cooled" livers.
It took 15 years of development to get the OrganOx device from the lab bench to the bedside. One of the biggest challenges was making the machine small enough to wheel into the back of an ambulance.
Early versions were the size of a large boardroom table and needed a team of trained experts to operate.
"All this research has been translated into two buttons - play and stop," said Prof Coussios.