First successful pig kidney transplant could hold key to reducing long dialysis waiting lists

A genetically modified pig kidney transplant has kept a 66-year-old man alive without dialysis, for 9 months, before he received a human kidney transplant. 

It is the first successful “bridge” transplant, between dialysis and a human transplant, using a pig kidney. 

The transplant was overseen by Massachusetts General Hospital (MHG) in the United States, with the findings published in the Lancet.

The MHG team used a Yucatan miniature pig kidney, genetically engineered to be compatible with a human immune system. 

The success is a crucial step in addressing the huge waiting times for people with kidney disease awaiting transplant. 

Waiting times increasing

According to Kidney Health Australia, kidney disease is set to increase by 42% by 2030. Dialysis units across Australia and New Zealand are being forced to ration lifesaving care for patients with kidney failure, reported the ABC this month. 

Key findings from a report by the Australian and New Zealand Society of Nephrology (ANZSN) and the Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry, include “waiting lists in more than 80% of Australian regions, machines out of service in 24% of Australian units, several jurisdictions operating above usual capacity levels, with particular pressure in regional and remote areas.”

InSight+reported last month about Australian hospitals attempting to improve quality of life on dialysis, and burden on hospitals, through peritoneal dialysis. 

Pig kidney transplant could be crucial step in reducing waiting times

Dr Leonardo V Riella is the lead author of the Lancet study and Medical Director for Kidney Transplantation at Mass General Brigham and Associate Professor of Medicine and Surgery at Harvard Medical School.

Dr Riella told InSight+ that xenotransplantation is an attempt to solve the problem of transplant waiting times.

“The fundamental problem we are trying to solve is the severe shortage of donor organs,” said Dr Riella.

“There are simply not enough human kidneys for the patients who need them. At our own transplant center, we have more than 1,400 patients on the kidney transplant waiting list. Many will spend years on dialysis, and some will unfortunately die or become too sick to receive a transplant before an organ becomes available.”

“This gap between the number of patients who need a kidney and the number of organs available is what makes xenotransplantation so important.”

Dr Riella said that he sees xenotransplantation as a potential bridge.

“[It’s] getting patients off dialysis while they continue to wait for a human kidney. Even that could have a major impact on patients’ health and quality of life.”

A long road to success

The road to xenotransplantation has been a long one, and there is still a long way to go, say the experts.

Professor Wayne Hawthorne is Professor of Transplantation, Department of Surgery, University of Sydney and Director of the National Pancreas and Islet Transplant Laboratories at Westmead Hospital and Westmead Institute for Medical Research (WIMR).

Prof. Hawthorne says that researchers have been doing xenotransplantation for 50, 60, 70 years — but that the significance of this most recent xenotransplantation is crossing the species barrier. 

“It was not always possible to cross species barrier. We could never do that before. So, we were doing it in the research setting. We've been testing this for 25, 30 years,” he said.

“Up until the last 4, 5, even 10 years ago with cells, we haven't been able to have a successful xenotransplant go more than a couple of days, a week, a month.”

“So, to get out to 9 months, in our field, we're looking at it as… a miracle.”

“Because if you look back at the very first human-to-human transplants, most of those failed within a couple of days, or a week. It took years for us to get kidney transplants, the most basic of the organ transplants, to survive for months, let alone years."

Prof. Hawthorne and others in the field have been making huge advances.

“We set up a pancreas transplant program 30-odd years ago. We’ve transplanted more than 700 patients with whole pancreas and kidney transplants to treat kidney failure and diabetes.”

“Kidneys are the most widely used, and that's why this has become more publicised. It's also the most transplanted organ because more people have renal failure than any of the other diseases put together.”

“Paralleling that, we set up a program called islet cell transplantation. That's where we take the pancreases that can't be used, and we then isolate the islet cells, the cells that produce insulin, that cure the diabetes.”

“The problem is, is we still don't have enough organ donors to produce enough islet cells to transplant the numbers of recipients we need to.”

The world organ transplant programs have increased organ donation, but it still not close to what is needed.

“We projected that decades ago, so we started looking at xenotransplantation as the new way that we could potentially solve this problem.”

Prof. Hawthorne leads researchers at the USYD, Westmead Hospital and WIMR using xenotransplantation in attempts to even cure diabetes.

In 2024, Prof. Hawthorne received just under $4 million, including in funding from the NHMRC, for his project ‘Xenotransplantation: a Next Generation Cure for Diabetes using Transgenic Porcine Islets.’

The team is poised to become the first in the world to take pancreatic islet cells from genetically modified pigs and transplant them into human patients.

“We’re now trying to get to the point where we can transplant these islet cells into patients” Hawthorne.

Supporting the future of xenotransplant 

Prof. Hawthorne said funding remains the biggest hurdle to overcome. 

"We just don't have the funding. It’s all good and well to develop these [procedures]. We need to increase the capacity to expand this clinically, but we need the infrastructure, the support for the staffing, the facilities, the immunosuppression, and all the rest of it."

“More and more patients are going onto dialysis and are going to need transplants. The more we can get off of dialysis, the more money we will save.” 

Dr Riella said that the longer-term ambition of their research is much greater than quality of life. 

“[It’s] to make xenotransplantation safe, reliable, and durable enough that outcomes ultimately approach those of human kidney transplantation. If we can achieve that, xenotransplantation could fundamentally change organ availability and allow us to offer transplantation to many more patients who need it.”

According to the authors, after roughly six months, damage developed in the MGH kidney’s blood vessels which progressed to organ failure. The kidney was removed approximately nine months after transplantation. 

The patient did not produce any detectable antibodies against the pig kidney, suggesting a different mechanism to that usually seen in organ transplant rejection.

“There is still much to learn, particularly about rejection and long-term graft function, but the progress is very encouraging.”