Scientists are inching closer to a major breakthrough in organ donation. This week, researchers at New York University announced that they transplanted a pig kidney to a human for the second time with no short-term issues, following their initial success two months earlier. Clinical trials of this technology are likely still a while away, though.
The procedure was performed in late November by a surgical team at NYU Langone Health. As with the first procedure, the doctors transplanted a kidney from a genetically modified pig into a living human body. The kidney wasn’t attached to its normal position in the body, but to blood vessels in the upper leg. It was then covered with a protective shield as the researchers observed it for 54 hours. During those hours, the kidney seemed to function as normal and no signs of rejection from the person’s body were detected.
The first transplant, performed in September, involved a human recipient considered to be brain-dead who was about to be taken off life-support; the recipient’s family agreed to help with the research. This time, according to the team’s announcement, the recipient was a functionally dead organ donor who was being maintained on a ventilator. The donor was found with the help of LiveOnNY, a nonprofit group that has reportedly enrolled 6.5 million organ donors in the greater New York City area.
“We have been able to replicate the results from the first transformative procedure to demonstrate the continued promise that these genetically engineered organs could be a renewable source of organs to the many people around the world awaiting a life-saving gift,” said lead surgeon Robert Montgomery, director of the NYU Langone Transplant Institute, in a statement from the university.
Animal-to-human transplantation, or xenotransplantation, has been a long-sought goal in medicine. One of the many challenges facing these transplants is that the organs of even closely related mammal species can have subtle but important differences that would quickly lead to rejection by the host body. One major limitation of donated pig organs is that pigs (and many other mammals) naturally produce a sugar called alpha-gal, which humans do not. But the pigs used by the NYU team were genetically engineered by Revivicor, a subsidiary of United Therapeutics Corporation, to not produce alpha-gal—in theory making them safe for human use.
Though xenotransplantation is controversial, opinion polls have suggested that most would accept the technology if it became widely available. For now, though, that possibility is still far off. Both surgeries were part of an ongoing research project by NYU to test the feasibility of their approach, and further studies will be needed to justify the leap to trials involving actual patients who would benefit from donation. But should all this work pay off, xenotransplantation could save the lives of many Americans who die annually while languishing on the transplant waiting list.
“With additional study and replication, this could be the path forward to saving many thousands of lives each year,” Montgomery said.