A pig’s liver has been transplanted into a human recipient for the first time in a ‘milestone’ for organ transfers between animals and people.
Scientists in China used a liver taken from a seven-month old Bama miniature pig which had been genetically modified to reduce the risk of rejection.
Once removed, it was kept ‘alive’ using a medical solution and chilled to 0-4C.
During the nine-hour-long surgery the recipient – a 50-year-old clinically dead man whose family had authorised the procedure – had the donor liver stitched to his blood vessels in his abdomen alongside his own liver.
Over the next 10 days, the donor liver successfully produced bile and maintained a stable blood flow.
The team hope that rather than a long-term solution, their procedure could one day be used as a temporary treatment for patients with liver failure while they wait for a human donor.
In the UK, there are more than 11,000 deaths due to liver disease each year. Around 700 people are currently on the waiting list for a transplant, and the average wait is three to four months.
The announcement follows a slew of recent breakthroughs, including transplanting a pig’s heart into a man and a woman currently living with a pig’s kidney.
Professor Lin Wang, one of the study’s authors from the Fourth Military Medical University in Xi’an, said: ‘The liver collected from the modified pig functioned very well in the human body.
‘It’s a great achievement. This surgery was really successful.
‘We examined the blood flow in the different vessels and arteries. The flow is very smooth. It functioned very well.’
The experiment was terminated after 10 days because of requests made by the patient’s family members.
The findings, published in the journal Nature, suggest modified livers can survive and function in human bodies, but further research on long-term outcomes is needed.
‘We have the opportunity in the future to solve the problem of a patient with severe liver failure,’ Professor Wang added.
‘It is our dream to make this achievement. The pig liver could survive together with the original liver of the human being and maybe it will give it additional support.’
He also expressed a desire to conduct further research on living, non-brain-dead human beings in the future, but stressed the complications and ‘many rules’ around this.
Earlier this year, a team at the University of Pennsylvania in Philadelphia connected a clinically dead person to a genetically modified pig’s liver located outside their body.
This is the first time, however, a pig liver has been transplanted into a human.
Rafael Matesanz, founder of the National Transplant Organisation in Spain, said: ‘This is the world’s first case of a transplant of a genetically modified pig liver into a brain-dead human.
‘The ultimate goal of the experiment was not to achieve a standard liver transplant, but to serve as a ‘bridge organ’ in cases of acute liver failure, while awaiting a human organ for a definitive transplant.’
Iván Fernández Vega, Professor of Pathological Anatomy at the University of Oviedo in Spain, described the procedure as a ‘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.
‘It is the first study to demonstrate that a genetically modified porcine liver can survive and exert basic metabolic functions – albumin and bile production – in the human body.’
Liver transplantation is the most effective treatment for end-stage liver diseases, but the demand for donor livers far exceeds the supply, according to the researchers.
Pigs are being considered as an alternative source of organs owing to their compatible physiological functions and size.
The pig for this surgery was provided by Doctor Deng-Ke Pan at Clonorgan Biotechnology Company.
It contained six genetic modifications – the deactivation of three pig genes and the introduction of three genes for human proteins.
This was crucial to help prevent the recipient from rejecting the pig organ – a regular hurdle in animal-to-human transplants.
The transplant follows more than 10 years of research into this process on animals. In 2013, scientists performed the first pig-to-monkey liver transplant.
Previous studies into kidney and heart transplants from pigs to humans have also been successful.
But whilst those organs have mostly one function, the multi-functionality of the liver was a ‘huge obstacle for us to overcome,’ Professor Wang said.
In January 2022, a dying man in the US became the first patient in the world to get a heart transplant from a genetically-modified pig.
David Bennett, who was suffering from terminal heart failure, underwent a nine-hour operation at the University of Maryland Medical Centre in Baltimore.
The 57-year-old survived for two months following the surgery, with doctors describing him as a ‘brave and noble patient who fought all the way to the end’.
Meanwhile, in November last year, Towana Looney became the fifth living person to receive a gene-edited pig kidney.
She has since made history as the longest-living recipient, and says she feels ‘like superwoman’.
