A pig's liver has been transplanted to a human recipient while they are alive for the first time in a 'landmark' for organ transfers between animals and humans.
Earlier this year scientists transplanted one that had been genetically modified to reduce risk of rejection into a clinically dead patient.
Now in a pivotal step forward, Chinese scientists have implanted a genetically modified pig's liver into a 71-year-old man while he was alive.
The patient who had liver cancer and late-stage liver disease wasn't eligible for a liver transplant or partial removal of the organ to treat the illnesses.
In the first month after the surgery, it showed promising results, not being rejected and functioning effectively.
But on day 38, it had to be removed after a serious complication, that involved an immune system reaction which damaged the lining of blood vessels.
Initially they were able to treat it with medication and a procedure to remove harmful factors from the blood.
However, the patient sadly went on to suffer episodes of gastrointestinal haemorrhage—bleeding in the digestive tract—and died on day 171.
Dr Beicheng Sun, one of the study's authors from the First Affiliated Hospital of Anhui Medical University, in China, said: ‘This case proves that a genetically engineered pig liver can function in a human for an extended period.
‘It is a pivotal step forward, demonstrating both the promise and the remaining hurdles, particularly regarding coagulation dysregulation and immune complications, that must be overcome.’
In this case, the liver which was genetically modified 10 times to prevent rejection came from a genetically modified Diannan miniature pig.
Transplanting organs from animals to humans is an emerging field known as xenotransplantation.
Experts hope it could pave the way for animal transplants to one day be an option for people on organ waiting lists.
It comes as latest figures show a record high 8,096 Britons, including 276 children are on waiting lists for organ transplants.
In the UK there are over 600 people on the waiting list for a liver transplant, and the average wait is three to four months.
There are several reasons people need a transplant including liver cancer and cirrhosis—scarring from late-stage liver disease—which the 71-year-old patient suffered from.
Dr Heiner Wedemeyer a professor at Hannover Medical School and co-editor of the Journal of Hepatology, where the findings were published, said ‘this report is a landmark in hepatology’—the branch of medicine concerned with the liver.
He continued: ‘It shows that a genetically modified porcine liver can engraft and deliver key hepatic functions in a human recipient.
‘At the same time, it highlights the biological and ethical challenges that remain before such approaches can be translated into wider clinical use.
‘Xenotransplantation may open completely new paths for patients with acute liver failure, acute-on-chronic liver failure, and hepatocellular carcinoma.
‘A new era of transplant hepatology has started.’
Dr Beatriz Domínguez-Gil, director of the National Transplant Organisation in Spain, added: ‘This is a new step in the advancement of xenotransplant therapy, which continues to progress in clinical development.
‘But it also highlights the significant obstacles that remain to be overcome such as the serious complication observed in this patient.
‘At the National Transplant Organization of Spain (ONT), we insist that these transplants are experimental.
‘Further work is needed to perfect the genetic modifications carried out, improve the immunosuppression used, and attempt to identify and address any complications that may develop early.
She continued: ‘Ideally, this should be done in properly designed clinical trials to evaluate their efficacy and safety in the short, medium, and long term.
‘However, these cases allow us to glimpse a future in which xenotransplantation is a clinical reality as a bridge therapy, particularly in the case of the liver, or as a destination therapy.’
