Surgeons have carried out the world’s first liver transplant from a pig into a human recipient.
The operation, carried out in China, used a liver from a pig that had been genetically modified to reduce the chance of the organ being rejected by a human immune system.
The organ successfully produced bile and essential proteins in a patient who was brain-dead, but still alive.
Relatives asked for the experiment to be stopped after 10 days, but the researchers say the organ could have functioned for longer.
They hailed the transplant as a “great achievement”, and European experts have called it a significant milestone that could save lives in future.
The surgical team, from Xijing Hospital in Xi’an, took the liver from a Bama miniature pig that had six key genes modified to improve compatibility of an organ when transplanted into a human.
According to results published in the science journal Nature, the liver functioned normally, with good blood flow and no signs of rejection.
Professor Lin Wang, who led the research team, said the transplant was carried out with full ethical approval from medical authorities and consent from the patient’s family.
“Surgery was really successful,” he told a news conference.
“The liver from the pig functioned very well in the human body. So it’s a great achievement.”
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Hearts and kidneys from genetically modified pigs have already been transplanted into a handful of living patients. Most died within weeks of the operation, but two people who had pig kidneys are understood to have survived in the United States.
Professor Wang said a liver transplant from a pig is far more complicated.
“A heart is just a pump, the kidney only produces urine,” he said.
“But the liver has many functions, so this is a huge obstacle for us to solve.”
Several research groups are experimenting with pigs raised in super-clean facilities for organ donation.
Pigs are used because their organs are similar in size and structure to those in a human. But key genes need to be modified to reduce the risk of them being attacked by a patient’s immune system after transplantation.
The Chinese researchers propose using pig organs as a temporary support, either to take the pressure off a patient’s liver so it can regenerate, or to give more time to find a permanent organ from a suitable human donor.
There are currently more than 600 patients on the waiting list for a liver transplant in the UK. The average wait for an organ from a deceased donor is three to four months.
Ivan Fernandez Vega, professor of pathological anatomy at the University of Oviedo in Spain, described the experiment as an important “milestone”.
“The clinical implications are highly relevant, as optimising this approach could expand the pool of available organs and save lives in liver emergencies,” he said.
The Chinese team is planning to repeat the experiment in more brain-dead patients, for longer periods, before progressing to the first clinical transplants in living people.
