The first patient to receive a kidney transplant from a genetically modified pig did so well that he was discharged from hospital on Wednesday, just two weeks after the groundbreaking operation.
The transplant and its encouraging result represent a remarkable moment in medicine, scientists say, possibly heralding an era of interspecies organ transplants.
Two previous organ transplants from genetically modified pigs have failed. Both patients received hearts and both died a few weeks later. In one patient, there was evidence that the immune system had rejected the organ, an ongoing risk.
But the kidney transplanted into Richard Slayman, 62, makes urine, removes waste from the blood, balances body fluids and performs other essential functions, according to his doctors at Massachusetts General Hospital.
“This moment – ​​leaving the hospital today with one of the cleanest bills of health I’ve had in a long time – is one I’ve been wishing for for many years to come,” he said in a statement released by the hospital. “Now it’s a reality.”
He said he had received “excellent care” and thanked his doctors and nurses, as well as well-wishers who reached out to him, including kidney patients waiting for an organ.
“Today marks a new beginning not only for me, but for them as well,” Mr Slayman said.
The procedure brings the prospect of xenotransplantation, or animal-to-human organ transplants, significantly closer to reality, said Dr. David Klassen, chief medical officer for the United Network for Organ Sharing, which manages the nation’s organ transplant system.
“Although there’s a lot of work to be done, I think the potential for this to benefit a large number of patients will be realized, and that’s been a question mark hanging over the field,” Dr. Klassen said.
Whether Mr. Slayman’s body will ultimately reject the transplanted organ is still unknown, Dr. Klassen noted. And there are other hurdles: A successful operation would have to be repeated in many patients and studied in clinical trials before xenografts are widely available.
If these transplants are to be scaled up and integrated into the health care system, there are “terrifying” logistical challenges, he said, starting with ensuring an adequate supply of organs from genetically modified animals.
Cost, of course, can become a major barrier. “Is that something we can really realistically attempt as a health care system?” Dr. Klassen said. “We have to think about that.”
Treating kidney disease is already a huge expense. End-stage kidney disease, the point at which organs fail, affects 1 percent of Medicare beneficiaries but accounts for 7 percent of Medicare spending, according to the National Kidney Foundation.
However, the medical potential for pig-to-human transplantation is enormous.
Mr. Slayman chose the experimental procedure because he was left with few options. He was having difficulty with dialysis due to problems with his blood vessels and was facing a long wait for a kidney donation.
The kidney transplanted into Mr Slayman came from a pig genetically engineered by the biotechnology company eGenesis. The company’s scientists removed three genes that could cause organ rejection, inserted seven human genes to enhance compatibility, and took steps to inactivate pig-borne retroviruses that can infect humans.
More than 550,000 Americans have kidney failure and need dialysis, and more than 100,000 are on the waiting list to receive a kidney transplant from a human donor.
In addition, tens of millions of Americans have chronic kidney disease, which can lead to organ failure. Black Americans, Hispanic Americans, and Native Americans have the highest rates of end-stage kidney disease. Black patients generally fare worse than white patients and have less access to a kidney donation.
While dialysis keeps people alive, the treatment of choice for many patients is a kidney transplant, which dramatically improves quality of life. But only 25,000 kidney transplants are performed each year, and thousands of patients die annually waiting for a human organ because there is a shortage of donors.
Xenotransplantation has been discussed for decades as a possible solution.
The challenge in any organ transplant is that the human immune system is primed to attack foreign tissue, causing life-threatening complications for recipients. Patients who receive organ transplants generally must take drugs intended to suppress the immune system’s response and preserve the organ.
Mr. Slayman showed signs of rejection on the eighth day after the operation, according to Dr. Leonardo V. Riella, medical director of kidney transplantation at Mass General. (The hospital’s parent organization, Mass General Brigham, developed the transplant program.)
The rejection was a type called acellular rejection, which is the most common form of acute transplant rejection. It can happen at any time but especially within the first year of organ transplantation. Up to 25 percent of organ recipients experience cellular rejection within the first three months.
The rejection was not unexpected, although Mr. Schleiman experienced it more quickly than usual, Dr. Riella said. Doctors were able to reverse the rejection with steroids and other drugs used to reduce the immune response.
“It was a roller coaster the first week,” said Dr. Riella. Reassuringly, he added, Mr. Slayman responded to the treatment like patients receiving organs from human donors.
Mr. Slayman is on several immunosuppressive medications and will continue to be closely monitored with blood and urine tests three times a week, as well as doctor visits twice a week.
His doctors don’t want Mr. Slayman to return to his job, at the state transportation department, for at least six weeks, and he must take precautions to avoid infections from the drugs that suppress his immune system.
“Ultimately, we want patients to get back to the things they love to do, to improve their quality of life,” said Dr. Riella. “We want to avoid restrictions.”
By Wednesday, Mr. Sleiman was clearly ready to go home, Dr. Riella said.
“When we first came in, there was a lot of concern and anxiety about what was going to happen,” said Dr. Riella. “But when we rounded him up at 7am this morning, you could see a big smile on his face and he was making plans.”
