Surgeons complete first-ever gene-edited pig kidney transplant

In a world first, surgeons at Massachusetts General Hospital successfully transplanted a genetically modified pig kidney into a person with chronic kidney disease. The historic procedure builds off of decades of research into gene editing of animal organs and could mark an inflection point in efforts to cut down on sometimes fatally lengthy transplant wait times. Recent advances in gene editing technology means procedures like these could become more common. 

The patient, a 62-year-old man from Massachusetts named Richard Slayman, has severe diabetes and hypertension and has been on dialysis for seven years. He eventually received a new kidney from a human donor but it began showing signs of failure after five years. Slayman was on a waiting list for another kidney when his doctors suggested the possibility of receiving an experimental kidney from a gene-edited pig.

“I saw [the transplant] not only as a way to help me, but a way to provide hope for the thousands of people who need a transplant to survive,” Slayman said in a statement. 

The modified pig was engineered by Massachusetts-based biotech firm eGenesis. Scientists used CRISPR gene editing technology to produce a pig with 69 gene modifications. Several of these modifications were meant to remove harmful pig genes that could provoke an immune response from the patent. Human genes were also added to the pig to improve the kidney’s compatibility and lessen the likelihood of the human body rejecting it. 

After around four hours of tense operating, surgeons in the room reportedly said they saw the transplanted kidney producing urine, a key sign the procedure was a success. The room filled with applause and cheers. 

“This represents a new frontier in medicine and demonstrates the potential of genome engineering to change the lives of millions of patients globally suffering from kidney failure,” eGenesis CEO Mike Curtis said in a statement. 

Why are scientists interested in gene-editing animal organs?

Scientists are hopeful that transplanting animal organs into humans, a practice called “xenotransplantation,” could one day supplement human organ transplants and cut down on lengthy transplant wait times. An estimated 36 million people in the US are affected by chronic kidney disease, 800,000 of which have end stage kidney disease or kidney failure according to the Centers for Disease Control. Once at that stage, patients are often forced to choose between going on a dialysis machine that filters their blood or applying for an organ transplant. Over 103,000 people in the US are currently on organ transplant wait list according to the Health Resource and Services Administration (HRSA). 

But lengthy wait times and a limited supply of able organ donors means many of those patients never end up receiving a transplant. The HRSA estimates 17 people die everyday while waiting for a new organ. Those lengthy wait times and lack of donors has also helped fuel an organ black market. 

Potential animal organ transplants aren’t just limited to kidneys. Surgeons at the University of Pennsylvania, for example, successfully implanted a gene-modified pig liver into a brain-stem dead person in 2022. Not long after that surgeons from the University of Maryland Medical Center implanted pig hearts into two fatally-ill patients. Though those two surgeries were successful, their end effect was limited. Both patients reportedly died less than two months after the procedures. Human immune systems react violently to organs from other species and try to reject them, an obstacle which makes these procedures particularly challenging.  

“If it were easy, we’d be doing it by now, but it’s not,” MGH Transplant Center Director Joren Madsen said in a statement. “The barrier to pig xenotransplantation is formidable.” 

Still, researchers are hopeful advancements in gene editing could lead to longer lasting benefits. Surgeons have previously transplanted genetically modified kidneys and livers to baboons. In one case, eGenesis claims a monkey implanted with a gene-edited pig kidney lived for two years following the surgery. Surgeons involved with Slayman’s procedure are similarly hoping his new kidneys could help him live for two more years. The FDA fast tracked approval for his particulate procedure as part of its “compassionate use” program intended for patients nearing the ends of their lives. Wider use of this procedure would require full FDA testing and approval. 

And while the historic procedure is both a feat of scientific and medical prowess, surgeons involved say the real credit belongs to the patient for marching into an unknown territory.

“The real hero today is the patient, Mr. Slayman, as the success of this pioneering surgery, once deemed unimaginable, would not have been possible without his courage and willingness to embark on a journey into uncharted medical territory,” MGH Transplant Center Director Joren C. Madsen said in a statement.