This week, a team at the University of Alabama said they were able to transplant two kidneys from a genetically modified pig into a brain-dead patient, a step beyond previous experiments that transplanted only one pig kidney. The Alabama doctors say the kidneys were able to function as expected and weren’t immediately rejected by the body.
In October 2021, doctors at New York University Langone Health reported that they had, for the first time, successfully transplanted a kidney from a genetically modified pig that was then able to function normally without rejection from the human body for two days. By December, the same team reported a second working transplant.
Both of these experiments were only meant to test the short-term feasibility of the procedure. They involved recipients who were deemed to be functionally dead and whose bodies were only being kept alive through life support. But earlier this month, a team at the University of Maryland Medical Center transplanted a pig heart into a living patient named David Bennett. Bennett had a terminal heart disease but was medically ineligible for a standard transplant or heart pump. And with both his consent and the permission of the Food and Drug Administration, the doctors were allowed to carry out the one-off experimental surgery.
This latest feat comes from doctors at the University of Alabama at Birmingham Marnix E. Heersink School of Medicine. It’s the first such transplant to be detailed in a peer-reviewed journal, an important step for validating any research. And it appears to be the first to transplant two of these modified kidneys into a single human.
As with the NYU transplants, the recipient was a brain-dead patient, and the experimental procedure was not intended to save the person’s life. The doctors transplanted the kidneys into the recipient’s abdomen and monitored them for 77 hours. During that time, the kidneys filtered blood, produced urine, and avoided rejection from the host body. The team’s findings were published Thursday in the American Journal of Transplantation.
“This game-changing moment in the history of medicine represents a paradigm shift and a major milestone in the field of xenotransplantation, which is arguably the best solution to the organ shortage crisis,” said lead author, Jayme Locke, director of the Comprehensive Transplant Institute at UAB’s Department of Surgery, in a statement from the university.
There are some key differences between all of these transplants. Namely, the NYU team relied on pigs that had only a single gene edited—one responsible for producing a sugar in their muscles that humans don’t make. This incompatibility is thought to be a major reason why past attempts to use animal organs for human transplants haven’t worked, since most mammals produce the sugar. But the pigs used by the UAB and the Maryland team had 10 genes edited to make them more compatible with humans. In all of the procedures, though, the genetically engineered pigs were supplied through the company Revivicor.
With their findings today, the UAB team firmly believes that their methods are ready to be tested out in clinical trials sooner than later.
“We have bridged critical knowledge gaps and obtained the safety and feasibility data necessary to begin a clinical trial in living humans with end-stage kidney failure disease,” Locke said.