Pig hearts could be available for human transplants within the next three years. This is not some off-the-wall prophecy or a number picked out of thin air, but the prediction of one Sir Terence English – the now 87-year-old surgeon who performed the UK's first successful heart transplant in 1979. 

Speaking to The Sunday Telegraph, English said his protege Christopher McGregor, who assisted him with that first heart transplant, is planning to carry out the first pig-to-human kidney transplant later in the year. If all goes well, it may just pave the way for similar operations involving more complex organs. 

"If the result of xenotransplantation is satisfactory with porcine kidneys to humans then it is likely that hearts would be used with good effects in humans within a few years," English told The Telegraph.

"If it works with a kidney, it will work with a heart. That will transform the issue."

Xenotransplantation is the process of transplanting an organ of one species into the body of another. Now, McGregor has developed a technique to tweak the pigs' genes to prevent immune system retaliation. According to English, it could provide the answer to the UK's (and the US') long transplant waiting lists.

According to The Telegraph, there are roughly 280 people in the UK on the heart transplant waiting list. Meanwhile, in the US, there are more than 110,000 people waiting for a lifesaving organ transplant of some kind – and in 2017, an average of 18 patients died every day during that wait.

Compared to, say, a kidney, heart transplants are extremely hard to come by. First, they must be in healthy condition. Second, they must be removed and transplanted within hours. And third, they must be a match (biologically and size-wise) for the patient. 

Pigs' hearts could prove a suitable alternative because they are anatomically similar to humans'. It is why they are so often used in medical trials. Take, for example, a study that looked into the possibility of using stem cell grafts to heal damaged tissue. And while on-demand pig transplants are still the stuff of fiction, scientists have been making headway when it comes to transplanting porcine organs into primates. Last year, a baboon survived more than six months after receiving a pig implant that had been gene-edited to prevent an immune system attack.

It was then euthanized, so we do not know what would have happened to it in the months since. It is also worth pointing out that the four other baboons underwent the surgery failed to survive the half-year mark.

In a similar vein, scientists are also delving into the brave new world of chimeras – i.e. an organism or tissue melded from the DNA of two or more species. This includes pig-human chimeras that could one day be used to grow organs for transplant (even if, for now, they are yet to make it past the embryo stage) and, according to some reports, human-monkey chimeras. 

The use of pig organs and chimeras will no doubt raise a number of ethical questions, but they could also offer a solution to the big (and growing) dilemma cardiovascular disease presents. As for English's prediction, time will tell if it plays out.

[H/T: The Sunday Telegraph]