The first patient to receive a kidney transplanted from a genetically modified pig is doing so well that he was discharged from the hospital on Wednesday, just two weeks after the groundbreaking surgery.
The transplant and its promising outcome represent a remarkable moment in medicine, scientists say, possibly heralding an era of cross-species organ transplantation.
Two previous organ transplants from genetically modified pigs have failed. Both patients received hearts, and both died weeks later. In one patient, there are signs that the immune system has rejected the organ, a constant risk.
But the kidney transplanted to Richard Slayman, 62, makes urine, removes waste products from the blood, balances body fluids and performs other basic 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 wanted to come to for years,” he said in a statement released by hospital. “Now it’s a reality.”
He said he received “extraordinary 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 technique brings the prospect of xenotransplantation, or animal-to-human organ transplants, closer to reality, said Dr. David Klassen, the chief medical officer for the United Network for Organ Sharing, which manages the nation’s organ transplant system.
“Although much work remains to be done, I think its potential to benefit a large number of patients will be realized, and that is a question mark hovering over the field,” said Dr. Class.
If the body of Mr. Slayman’s transplanted organ is still unknown, said Dr. Class. And there are other obstacles: A successful operation needs to be replicated in many patients and studied in clinical trials before xenotransplants become widely available.
If these transplants are to be scaled up and integrated into the health care system, there are “terrible” logistical challenges, he said, starting with ensuring an adequate supply of organs from genetically engineered animals.
Cost, of course, can be a big obstacle. “Is this something we can try as a health care system?” said Dr. Class. “We’ll have to think about that.”
Treatment of kidney disease is already very expensive. 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.
But the medical potential for pig-to-human transmission is enormous.
Mr. Chosen Slayman takes the experimental approach because he has very few options left. He is struggling with dialysis because of problems with his blood vessels, and he faces a long wait for a kidney donation.
The kidney transplanted to Mr. Slayman came from a pig genetically engineered by the biotech company eGenesis. The company’s scientists removed three genes that can trigger organ rejection, inserted seven human genes to improve compatibility and took steps to inactivate retroviruses carried by pigs that can infect the person.
More than 550,000 Americans have kidney failure and need dialysis, and more than 100,000 are on the waiting list to receive a transplanted kidney 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 are generally worse off than white patients and have less access to a donated kidney.
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 each year waiting for a human organ because of a shortage of donors.
Xenotransplantation has been discussed for decades as a potential solution.
The challenge with any organ transplant is that the human immune system is primed to attack foreign tissues, causing life-threatening complications for recipients. Patients receiving transplanted organs generally must take medications intended to suppress the immune system’s response and preserve the organ.
Mr. Slayman showed signs of rejection on the eighth day after surgery, according to Dr. Leonardo V. Riella, medical director for kidney transplantation at Mass General. (The hospital’s parent organization, Mass General Brigham, developed the transplant program.)
The rejection is a type called cellular rejection, which is the most common form of acute graft rejection. It can happen at any time but especially within the first year of an organ transplant. Up to 25 percent of organ recipients experience cellular rejection within the first three months.
The rejection was unexpected, although Mr. Slayman experienced it more quickly than usual, said Dr. Riella. Doctors have been able to reverse the rejection with steroids and other drugs used to reduce the immune reaction.
“It was a roller coaster the first week,” said Dr. Riella. Reassuringly, he added, Mr. Slayman responded to treatment like patients receiving organs from human donors.
Mr. Slayman is taking several immunosuppressive medications, and he will continue to be monitored closely with blood and urine tests three times a week, as well as doctor visits twice a week.
His doctors did not want Mr. Slayman will be out of work, at the state transportation department, for at least six weeks, and he must be careful to avoid infections due to drugs that suppress his immune system.
“Ultimately, we want patients to get back to the things they enjoy doing, to improve their quality of life,” said Dr. Riella. “We want to avoid restrictions.”
By Wednesday, it was clear that Mr. Slayman, said Dr. Riella.
“When we first came in, he had a lot of apprehension and anxiety about what was going to happen,” said Dr. Riella. “But when we approached him this morning at 7 o’clock, you could see the big smile on his face and he was making plans.”
