Pig heart transplants could be performed by the NHS in the next decade, according to a leading expert.
Xenotransplantation – using animal organs for people – has long been touted as a panacea for the organ donor shortage, but the process is rife with difficulties.
Pigs are anatomically very similar to humans and therefore they are the best-suited animal donor candidate.
Last week, a genetically modified pig heart was transplanted into a chronically ill person in the US in a world first and it has thus far been a success, with the patient recovering well.
“The unwritten joke in the field of transplantation was that xenotransplantation has always been around the corner, but it has remained around the corner,” Prof Gabriel Oniscu, ESOT President-Elect of the European Society of Organ Transplantation and director of the Edinburgh Transplant Centre, told The Telegraph.
“Now I think it is not around the corner anymore, it’s on the straight line.
“In the past, we’ve always said it will be five to 10 years [until transplantation is a reality as a treatment], but it’s never been the case. I think now we are certainly looking within this timespan. I’m hopeful that it will happen.”
He said he could not see pig organs being given to people on the NHS in the next five years, but that they could be mainstream in the next decade, if proven to be safe and effective.
Prof Oniscu’s comments come on the back of 57-year-old David Bennett, an American from Maryland with terminal heart disease, receiving a pig heart from Dr Bartley Griffith.
Mr Bennett was ineligible for a human organ due to poor health, and said the groundbreaking surgery was “a shot in the dark”, but acknowledged it was his only option.
With no alternative treatment available, the US FDA gave emergency authorisation for the unprecedented and experimental procedure.
Prof Oniscu called the case “a fantastic breakthrough” and a “landmark” that will catalyse the field but emphasised it is highly experimental.
“We will learn a lot from this case whatever the outcome may be, it will advance the field significantly because you will know what the next set of changes and the next set of modifications should need to be to allow this to become mainstream. I mean, you’re really looking at an off-the-shelf organ, which is an immense development.”
He added that pigs are also being looked at as sources of livers and pancreases as well as hearts.
“I think you’re looking at potentially all solid organs being available from such a source,” he told The Telegraph.
Success for researchers
Researchers have spent decades grappling with how to stop organs from another species being rejected by a human host, and recently had success with porcine hearts in bonobos and kidneys in a braindead human.
Prof Chris Denning, Professor of Stem Cell Biology at the University of Nottingham, said that pigs have a gene that produces a specific molecule called α(1,3)galactosyl transferase, which is foreign to humans.
“This triggers an immediate and aggressive immune response, called hyperacute rejection,” he said. “Within minutes, the human body attacks the foreign organ to reduce it to a messy pulp.”
He believes that the pig used in the Maryland transplant – which was produced by a company called Revivicor, a spin-out company from PPL Therapeutics which created Dolly the sheep, the world’s first clone – likely had this specific gene deleted.
“The fact that the human patient is alive after a few days indicates that immediate hyperacute rejection has been avoided, which is the first hurdle,” Prof Denning added.
“Only time will tell whether there are issues with chronic rejection.”
“I think significant numbers [of the medical and surgical hurdles] have been overcome now,” added Prof Oniscu.
“It’s one thing to have a successful immediate transplant where you have removed the risk of hyper acute or acute rejection, but rejection can still happen in the next few weeks and months for this recipient.”
A spokesperson for NHS Blood and Transplant said: “This latest development makes the possibility of transplantation between animals and humans a potentially safe and ‘attainable’ future treatment option.
“However, there is still some way to go, before transplants of this kind become an everyday reality.”