Surgeons in Boston transplanted a kidney from a genetically modified pig into a sick 62-year-old man, the first operation of its kind. If successful, the discovery offers hope to hundreds of thousands of Americans whose kidneys have failed.
So far the signs are promising.
The kidneys remove waste products and excess fluid from the blood. The new kidney began producing urine shortly after the surgery last weekend, and the patient’s condition continues to improve, according to doctors at Massachusetts General Hospital, known as Mass General. He is already walking the halls of the hospital and may be discharged soon.
The patient is black, and the procedure may be of particular importance to black patients, who have high rates of end-stage renal disease.
A new source of kidneys “could solve an intractable problem in the field — the inadequate access of minority patients to kidney transplants,” said Dr. Winfred Williams, associate chief of nephrology at Mass General and the patient’s primary nephrologist.
If kidneys from genetically modified animals can be transplanted on a large scale, dialysis “will become obsolete,” said Dr. Leonardo V. Riella, medical director of kidney transplantation at Mass General. The hospital’s parent organization, Mass General Brigham, developed the transplant program.
More than 800,000 Americans have kidney failure and require dialysis, a process that filters toxins from the blood. More than 100,000 are on a waiting list to receive a kidney transplant from a living or deceased human donor. End-stage kidney disease is three times more common in black Americans than in white Americans.
In addition, tens of millions of Americans have chronic kidney disease, which can lead to organ failure.
While dialysis keeps people alive, the gold standard treatment is an organ transplant. Thousands of patients die annually waiting for a kidney, however, because there is an acute shortage of organs. Just 25,000 kidney transplants are performed each year.
Xenotransplantation—implanting an organ from an animal into a human—has been suggested for decades as a potential solution that could make kidneys much more widely available. However, the human immune system rejects foreign tissue, causing life-threatening complications, and experts note that long-term rejection can occur even when donors are well-matched.
In recent years, scientific advances including gene editing and cloning have brought xenografts closer to reality, making it possible to modify animal genes to make organs more compatible and less likely to be rejected by the immune system.
The kidney came from a pig made by the biotech company eGenesis, which removed three genes involved in the organ’s potential rejection. In addition, seven human genes were introduced to enhance human compatibility. Pigs carry retroviruses that can infect humans, and the company also inactivated the pathogens.
In September 2021, surgeons at NYU Langone Health in New York City attached a kidney from a genetically modified pig to a brain-dead man and watched as it began to function and urinate. Shortly thereafter, scientists at the University of Alabama at Birmingham announced that they had performed a similar procedure with similar results.
Surgeons at the University of Maryland have twice transplanted hearts from genetically modified pigs into patients with heart disease. While the organs were working and the first did not appear to be rejecting, both patients, who had advanced disease, died shortly afterwards.
(Patients who agree to these cutting-edge experimental treatments are usually extremely ill and have few options available; they are often too ill to qualify for the waiting list for a valuable human organ or ineligible for other reasons.)
Boston transplant patient Richard “Rick” Slayman, a supervisor for the state Department of Transportation, had suffered from diabetes and hypertension for many years and had been treated at Mass General for more than a decade.
After his kidneys failed, Mr Slayman was on dialysis for seven years, and finally received a human kidney in 2018. But the donated organ failed within five years and he developed other complications, including congestive heart failure, said Dr Williams.
When Mr. Sleiman resumed dialysis in 2023, he experienced serious vascular complications — his blood vessels clotted and failed — and required repeated hospitalizations, Dr. Williams said.
Mr Slayman, who continued to work despite his health problems, faced a long wait for another human kidney and “became desperate”, Dr Williams said. “He said, ‘I can’t go on like this. I can’t keep doing this.’ I started thinking about emergency measures we could take.”
“He would have to wait five to six years for a human kidney. He wouldn’t have been able to survive it,” added Dr Williams.
When Dr. Williams asked Mr. Schleiman about taking a pig kidney, Mr. Schleiman had many questions but ultimately decided to go ahead.
“I saw this not only as a way to help me, but as a way to give hope to thousands of people who need a transplant to survive,” he said in a statement provided by Mass General.
Mr. Slayman’s new kidney appears to be functional, so far, and has been able to stop dialysis. The new pig kidney produces urine and filters out creatinine, a waste product.
Other measures are also improving daily, his doctors said. Doctors will continue to monitor Mr. Slayman for signs of organ rejection.
“He looks like himself. It’s remarkable,” Dr. Williams said.
The operation was not without its critics. Xenotransplantation raises the prospect of even greater animal exploitation and can introduce new pathogens into human populations, said Kathy Guillermo, senior vice president at People for the Ethical Treatment of Animals.
“Using pigs as a source of spare parts is dangerous for human patients, deadly for animals and may cause the next pandemic,” he said. “It is impossible to eliminate, or even detect, all viruses carried by pigs. Researchers should focus on cleaning up the organ donation system and leave the animals alone.”
The four-hour operation was performed by a team of surgeons, including Dr. Tatsuo Kawai, director of the Legorreta Clinical Tolerance Transplant Center at Mass General, and Dr. Nahel Elias.
The procedure was conducted under a Food and Drug Administration protocol known as a palliative-use grant, which is given to patients with a life-threatening illness who may benefit from an unapproved treatment. The protocol also used new drugs to suppress the immune system and prevent organ rejection.
“He is extremely courageous to step forward,” Dr. Williams said of Mr. Sleiman. “I take my hat off to him. He has a huge contribution to make to that.”
