A patient who received a kidney transplant from a genetically modified pig did so well that he was discharged from the hospital two weeks after the operation.
Scientists and doctors say the transplant and its promising results represent an important moment in medicine, perhaps the beginning of a new era – cross-species organ transplantation.
Two previous organ transplants from genetically modified pigs had failed. Both patients received heart transplants, and both died within weeks.
The pig kidney transplanted into 62-year-old Richard Slayman is working normally, according to his doctors at Massachusetts General Hospital: producing urine, removing waste from the blood and generally doing everything a healthy kidney should do. Sleiman does not need dialysis for the first time in many years. He said he received “exceptional care” and thanked his doctors and nurses and everyone who has reached out to him with kind words, including patients awaiting kidney transplants today. “Today is a new beginning not only for me, but also for them,” Sleiman said.
The success of this transplant is moving toward the use of xenotransplantation (animal-to-human organ transplantation), said Dr. David Klassen, chief medical officer of the United Network for Organ Sharing. He noted that it is not yet known whether Sleiman’s body will reject the transplanted organ. Scientists will closely monitor the patient’s recovery process.
But organ transplants will have to be repeated on many patients and studied in clinical trials before xenografts become widely available.
If these transplants are to scale up and enter the healthcare system, there will be big logistical challenges, Klassen said, the first of which is securing enough organs from genetically engineered animals.
Sleiman chose the experimental procedure because he had no other options. He had difficulty with dialysis due to blood vessel problems and had to wait a long time for a donor kidney.
The kidney transplanted into Sleiman came from a pig genetically modified by the biotech company eGenesis. The company’s scientists removed three genes that could cause organ rejection, inserted seven human genes to improve compatibility, and took steps to inactivate porcine retroviruses that can infect humans.
More than 550,000 Americans have kidney failure and require dialysis, and more than 100,000 people are on a waiting list for a human kidney transplant. Tens of millions suffer from chronic kidney disease.
About 25,000 kidney transplants are performed annually, and thousands of patients die each year waiting for a human organ due to a shortage of donors.
The problem with any organ transplant is that the person’s immune system attacks the foreign organ, causing life-threatening complications. Organ transplant patients typically must take medications designed to suppress the immune system’s response and are therefore at increased risk of external infections.
According to Dr. Leonardo V. Riella, medical director of kidney transplantation at Massachusetts General Hospital, Sleiman began showing signs of rejection on the eighth day after surgery. But doctors were able to successfully normalize the patient’s condition. What’s encouraging, Riella said, is that Sleiman responded to treatment the same way as patients who receive organs from human donors.
Sleiman is taking several immunosuppressive medications and will continue to be closely monitored. Doctors do blood and urine tests three times a week, and Sleiman must see a doctor twice a week.
Doctors intend to gradually lift all restrictions “We want patients to return to what they like to do,” says Dr. Riella.
Scientists and doctors are confident that the medical potential of pig organ transplantation into humans is enormous.