What went behind the ‘breakthrough’ pig to human kidney transplant in New York

In 1997, India had seen a similar operation, when a transplant surgeon from Assam had conducted a pig-to-human heart and lung transplant in Guwahati. The patient, though, died a week later.

Dr. Robert Montgomery, the H. Leon Pachter, MD, Professor and chair of the Department of Surgery at NYU Langone and director of its Transplant Institute, prepares sutures for use in the xenotransplantation surgery. | Photo: Joe Carrotta for NYU Langone Health

New Delhi: For the first time in history, a medical team in the US was able to successfully transplant a pig’s kidney to a human patient.

The breakthrough procedure was performed by surgeons at NYU Langone Health, using a kidney that had been grown in a genetically altered pig. The patient who received the kidney was brain-dead and was being kept on a ventilator, according to a report by The New York Times.

The kidney was attached to blood vessels in the patient’s upper leg outside the abdomen. The NYT report quoted Dr Robert Montgomery, the director of the NYU Langone Transplant Institute, as saying that the organ had “started functioning normally, making urine almost immediately”.

Xenotransplantation, i.e. the transplantation of organs from one species to another, is not a new phenomenon. 

In India too, in 1997, a transplant surgeon from Assam, Dr Dhani Ram Baruah, along with Hong Kong surgeon Dr Jonathan Go Kei-Shing had conducted a pig-to-human heart and lung transplant in Guwahati. The surgery, however, landed him in hot waters following the patient’s death.

Here’s a look at the history of xenotransplantation, the challenges, and how the particular procedure in the US was conducted.

All about xenotransplantation

Humans have been intrigued by the idea of transplanting organs from animals to humans for eons now, as evidenced by a host of mythological characters — from Ganesh in Hinduism to Daedelus in Greek mythology.

The earliest mention of xenotransplantation in scientific literature appears in 1905 in France, when slices of rabbit kidney were transplanted in a child who was suffering from chronic kidney insufficiency.

A paper on Xenotransplantation: A Historical Perspective by Columbia University researcher Keith Reemtsma, noted that the immediate results had been excellent. In 1906, two other instances of transplantations had been recorded — one from a pig and another from a goat, although neither graft functioned.

Since then, there have been many cases of xenotransplantation that have been performed the world over.

All India Institute of Medical Sciences (AIIMS) nephrologist Sandeep Mahajan told ThePrint that the earlier cases involved organs from non-human primates like chimpanzees and baboons.

“So, in the early 1910s, 1960s, even in the 1980s this was the case. We had a heart transplant from a baboon… But now, pigs are the easiest animals to transplant from, they are closest to us and are more abundant than primates,” Mahajan told ThePrint. 

Over the past several years, the notion has been gaining momentum with many, including renowned surgeon Terence English, advocating for the use of pig organs. Then, in 2018, a research study published in the Nature journal proved the viability of using genetically modified pig hearts in baboons. 

But, the procedure conducted this week was the first successful case where an entire organ was transplanted from a pig to a human. 

The NYT report quoted Dr Dorry Segev, a professor of transplant surgery at Johns Hopkins University School of Medicine in the US, who described it as a “big, big deal”.

How NYU doctors did it

The xenotransplantation of the pig’s kidney by the NYU Langone Health doctors involved the overcoming of a barrier.

“The basic barrier to xenotransplantation is the novel antigens, which the animals have, which the humans don’t have. So the body attacks the organs vigorously and rejects that organ very fast,” explained Mahajan. 

This is what had necessitated the genetic modification of the pig. 

Human bodies tend to reject pig tissues as they carry a gene that codes for a sugar molecule called alpha-gal, which “can send the human immune system into a frenzy” and lead to the organ being rejected.

So, Mahajan elucidated, “a normal pig was genetically modified to not express this gal system”, which means it lacks the sugar-producing gene. 

“This is a unique experiment in the sense, they’ve transplanted the whole organ into a human…they kept him (the patient) for three days wherein the organ was not rejected,” Mahajan added.

A controversial case in India

India had also seen a case of xenotransplantation 24 years ago, although that story had a tragic ending.

In January 1997, news emerged of a cardiac surgeon in Assam, Dr Dhani Ram Baruah, transplanting pig organs into a 32-year-old man with end-stage heart disease. Baruah is said to have carried out the procedure on the patient as a last resort with consent from their family.

A week after the transplant procedure, the patient died of multiple infections, which led to Baruah being detained for 40 days for “violating the human organ transplant laws in India”.

Over two decades on, the doctor told ThePrint that his career “was totally disturbed due to the number of restrictions put by the court” and he eventually had to divert his focus from xenotransplantation to genetic engineering. He now runs the runs the Dr Dhaniram Heart Institute and Research Centre in Sonapur, about 20 km from Guwahati.

Comparing the procedure he had performed and the one that was done by the US doctors, Baruah said his “procedure was quite different”.

“I did not do any genetic alteration in the pig’s organ and instead came up with an anti-hyperacute rejection therapy, which was given to that pig organ so that it can be accepted by the human body easily,” he said. “I did not use any immunosuppression and additionally removed preformed antibodies from human blood so that it had given extra protection for acceptance.”

Mahajan said the human body is still likely to have been prone to many more rejections in the procedure Baruah had performed. “Unless you’re able to cleanse the body of those antibodies, the body would keep on forming antibodies again and again,” he said.

He added that although this week’s surgery was a “proof of concept”, there’s still a long way to go.

“It (xenotransplantation) would reduce our dependence on various organs which obviously are very scarce…[but] there are obviously a lot of challenges — medical, ethical and religious,” he said.

(Edited by Amit Upadhyaya)