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| Surgeons in New York have successfully attached a kidney grown in a genetically altered pig to a human patient and found that the organ worked normally, a scientific breakthrough that one day may yield a vast new supply of organs for severely ill patients. |
| Researchers have long sought to grow organs in pigs that are suitable for transplantation into humans. Technologies like cloning and genetic engineering have brought that vision closer to reality in recent years, but testing these experimental organs in humans has presented daunting ethical questions. |
| So surgeons at N.Y.U. Langone Health took an astonishing step: With the family’s consent, they attached the pig’s kidney to a brain-dead patient who was kept alive on a ventilator, and then followed the body’s response while taking measures of the kidney’s function. It is the first operation of its kind. |
| The researchers tracked the results for just 54 hours, and many questions remained to be answered about the long-term consequences of such an operation. The procedure will not be available to patients any time soon, as there are significant medical and regulatory hurdles to overcome. |
| Still, experts in the field hailed the surgery as a milestone. |
| “This is a huge breakthrough,” said Dr. Dorry Segev, a professor of transplant surgery at Johns Hopkins School of Medicine who was not involved in the research. “It’s a big, big deal.” |
| A steady supply of organs from pigs — which could eventually include hearts, lungs and livers — would offer a lifeline to the more than 100,000 Americans currently on transplant waiting lists, including the 90,240 who need a kidney. Twelve people on the waiting lists die each day. |
| An even larger number of Americans with kidney failure — more than a half million — depend on grueling dialysis treatments to survive. In large part because of the scarcity of human organs, the vast majority of dialysis patients do not qualify for transplants, which are reserved for those most likely to thrive after the procedure. |
| The surgery was first reported by USA Today on Tuesday. The research has not yet been peer-reviewed nor published in a medical journal. |
| The transplanted kidney was obtained from a pig genetically engineered to grow an organ unlikely to be rejected by the human body. In a close approximation of an actual transplant procedure, the kidney was attached to blood vessels in the patient’s upper leg, outside the abdomen. |
| The organ started functioning normally, making urine and the waste product creatinine “almost immediately,” according to Dr. Robert Montgomery, the director of the N.Y.U. Langone Transplant Institute, who performed the procedure in September. |
| Although the kidney was not implanted in the body, problems with so-called xenotransplants — from animals like primates and pigs — usually occur at the interface of the blood supply and the organ, where human blood flows through pig vessels, experts said. |
| The fact that the organ functioned outside the body is a strong indication that it will work in the body, Dr. Montgomery said. |
| “It was better than I think we even expected,” he said. “It just looked like any transplant I’ve ever done from a living donor. A lot of kidneys from deceased people don’t work right away, and take days or weeks to start. This worked immediately.” |
| Last year, 39,717 residents of the United States received an organ transplant, the majority of them — 23,401 — receiving kidneys, according to the United Network for Organ Sharing, a nonprofit that coordinates the nation’s organ procurement efforts. |
| Genetically engineered pigs “could potentially be a sustainable, renewable source of organs — the solar and wind of organ availability,” Dr. Montgomery said. |
| The prospect of raising pigs to harvest their organs for humans is bound to raise questions about animal welfare and exploitation, though an estimated 100 million pigs already are killed in the United States each year for food. |
| “Pigs aren’t spare parts and should never be used as such just because humans are too self-centered to donate their bodies to patients desperate for organ transplants,” said a statement from the organization People for the Ethical Treatment of Animals, or PETA. |
| Among transplantation experts, reactions ranged from cautiously optimistic to ebullient, though all acknowledged the procedure represented a sea change. |
| While some surgeons speculated that it could be just months before genetically engineered pigs’ kidneys are transplanted into living human beings, others said there was still much work to be done. |
| “This is really cutting-edge translational surgery and transplantation that is on the brink of being able to do it in living human beings,” said Dr. Amy Friedman, a former transplant surgeon and chief medical officer of LiveOnNY, the organ procurement organization in the greater New York area. |
| The group was involved in the selection and identification of the brain-dead patient receiving the experimental procedure. The patient was a registered organ donor, and because the organs were not suitable for transplantation, the patient’s family agreed to permit research to test the experimental transplant procedure. |
| Dr. Friedman said she envisioned using hearts, livers and other organs grown in pigs, as well. “It’s truly mind-boggling to think of how many transplants we might be able to offer,” she said, adding, “You’d have to breed the pigs, of course.” |
| Other experts were more reserved, saying they wanted to see whether the results were reproducible and to review data collected by N.Y.U. Langone. |
| “There’s no question this is a tour de force, in that it’s hard to do and you have to jump through a lot of hoops,” said Dr. Jay A. Fishman, associate director of the transplantation center at Massachusetts General Hospital. |
| “Whether this particular study advances the field will depend on what data they collected and whether they share it, or whether it is a step just to show they can do it,” Dr. Fishman said. He urged humility “about what we know.” |
| Many hurdles remain before genetically engineered pigs’ organs can be used in living human beings, said Dr. David Klassen, chief medical officer of the United Network for Organ Sharing. |
| While he called the surgery “a watershed moment,” he warned that long-term rejection of organs occurs even when the donor kidney is well-matched, and “even when you’re not trying to cross species barriers.” |
| The kidney has functions in addition to clearing blood of toxins. And there are concerns about pig viruses infecting recipients, Dr. Klassen said: “It’s a complicated field, and to imagine that we know all of the things that are going to happen and all the problems that will arise is naïve.” |
| The combination of two new technologies — gene editing and cloning — has yielded genetically altered pig organs. Pig hearts and kidneys have been transplanted successfully into monkeys and baboons, but safety concerns precluded their use in humans. |
| “The field up to now has been stuck in the preclinical primate stage, because going from primate to living human is perceived as a big jump,” Dr. Montgomery said. |
| The kidney used in the new procedure was obtained by knocking out a pig gene that encodes a sugar molecule that elicits an aggressive human rejection response. The pig was genetically engineered by Revivicor and approved by the Food and Drug Administration for use as a source for human therapeutics. |
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