A Gene-Edited Pig Kidney Was Just Transplanted Into a Person for the First Time

A 62-year-old Massachusetts man with failing kidneys is the first living patient to receive a genetically altered kidney from a pig.

In a world first, surgeons in Boston have transplanted a genetically altered pig kidney into a 62-year-old man. The procedure is a step toward providing more readily available organs to patients who are in desperate need of a transplant.

The four-hour surgery was carried out on March 16 at Massachusetts General Hospital. Shortly after the kidney was placed in the patient’s body, it started producing urine—a sign that it was functioning as it should. Tatsuo Kawai, one of the surgeons involved, said the operating room erupted in applause. “It was truly the most beautiful kidney I have ever seen,” he said in a press conference on Thursday.

The patient, Richard Slayman of Weymouth, Massachusetts, is recovering well and is expected to be discharged soon, according to his medical team.

The surgery marks the latest advance for xenotransplantation—the use of animal organs in people—which scientists have been pursuing for decades due to a shortage of suitable human donor organs. In the United States alone, more than 100,000 people are on the transplant waiting list, and 17 people die each day waiting for an organ. A kidney is the most common organ in need.

But there’s a big obstacle to transplanting pig organs into the human body. “If it were easy, we’d be doing it by now, but it’s not,” said Joren Madsen, director of the Massachusetts General Hospital Transplant Center, during Thursday’s briefing. “The human immune system reacts incredibly violently to a pig organ.”

Researchers have turned to gene-editing technology to reduce the possibility of rejection. Slayman’s new kidney came from a donor pig bred by eGenesis of Cambridge, Massachusetts. Scientists at the company used Crispr to make 69 genetic edits to the pig—including removing harmful pig genes and adding certain human genes. They also used Crispr to inactivate innate viruses found in the pig genome that could hypothetically infect a human recipient.

Scientists are also exploring using gene-edited pig hearts in people. So far, two such transplants have been carried out in patients who were too ill to be eligible for a human donor heart. In both cases, the patients lived for less than two months.

Mike Curtis, CEO of eGenesis, says the kidney transplant that happened last weekend is different in a few key ways. “Here, we’re dealing with a patient that’s relatively healthy, was a candidate for human kidney transplant, and just because of the current allocation, was never really going to get one. He was going to spend the rest of his life on dialysis,” Curtis told WIRED in an interview.

Melissa Mattola-Kiatos, RN, Nursing Practice Specialist, removes the pig kidney from its box to prepare for

transplantation. Courtesy of Massachusetts General Hospital

Slayman received his first kidney transplant in 2018 from a human donor. The donor kidney initially functioned well, but Slayman started to go into kidney failure after years of living with diabetes. Diabetes is the leading cause of kidney disease, which can eventually result in kidney failure.

He had no choice but to go on dialysis, a treatment that removes excess fluid and waste from a person’s blood. But the dialysis caused complications—his blood vessels were clotting and failing. Slayman wound up in the hospital regularly and endured dozens of procedures to try to fix the problem.

“Slowly but surely, I witnessed my patient becoming increasingly despondent and depressed over his dialysis situation,” Winfred Williams, a kidney specialist and member of Slayman’s medical team, said on Thursday.

Finally, Williams suggested a pig kidney transplant. Slayman agreed. “I saw it 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 released by Massachusetts General Hospital.

The procedure was performed under the Food and Drug Administration’s “compassionate use” pathway, which allows a patient with a life-threatening condition to access an experimental treatment when no other options exist. Slayman is also receiving an infusion of novel immunosuppressant drugs to prevent rejection of the organ. His medical team is currently monitoring his kidney function using ultrasound.

The Massachusetts team thinks the ideal candidate for a pig kidney will be a patient who was approved for a regular human kidney transplant but has a long wait time for a donor.

The pig kidney transplant comes on the heels of a procedure in January, in which surgeons at the University of Pennsylvania successfully attached a gene-edited pig liver to a brain-dead person and found that the organ functioned normally for 72 hours. The liver, also from eGenesis, contained the same 69 edits as Slayman’s kidney.

The liver is a more complicated organ because of the many functions it performs, so researchers don’t think pig livers are ready to be used in place of human ones just yet. Instead, they could be used outside the body and connected to patients who are waiting for a human organ or those who need temporary support while their own liver recovers.

Researchers have been working up to transplanting a modified pig kidney in a person. Last year, eGenesis reported that a kidney from one of its edited pigs functioned in a monkey for more than two years. And scientists at New York University and the University of Alabama at Birmingham have transplanted gene-edited pig kidneys into brain-dead patients to observe how well the organs function.

Jayme Locke, an abdominal transplant surgeon at the University of Alabama at Birmingham who has overseen some of those experiments, was thrilled to hear about the Boston kidney transplant. “This is wonderful news, and it’s great to see it move into the clinic,” she told WIRED in an interview.

Locke says the recent flurry of xenotransplantation experiments shows that the idea of using pig organs in people is gaining momentum and is here to stay. “I think it really has staying power, and it’s going to really revolutionize the field and hopefully offer organs to all those in need,” she says.

Locke’s team is also looking to do pig-to-human kidney transplants. She said she has several patients in mind for the procedures and is just waiting on the FDA to give the green light. “We’re ready to go.”

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