2024 marked a big year for the field of xenotransplantation, with surgical teams at several health systems completing historic procedures that could pave the way for broader adoption of animal-to-human organ transplants.
In January, researchers at Philadelphia-based Penn Medicine announced the first successful experiment of circulating a deceased donor's blood through a genetically edited pig liver outside of their body. While patients with heart and kidney failure can be kept alive with mechanical options, no similar therapy exists for patients with liver failure. This experimental method could be used as a temporary treatment to extend the lives of patients awaiting a liver transplant if proved safe and feasible, researchers said.
Surgeons at Massachusetts General Hospital in Boston completed the year's next historic transplant milestone in March, reporting the world's first successful transplant of a genetically edited pig kidney. The kidney contained 69 genomic edits to improve its compatibility with humans. Richard Slayman, 62, underwent the four-hour procedure as a treatment for end-stage kidney disease and died 51 days after his procedure from an "unexpected cardiac event," his surgeon said. There was no indication his body had rejected the donor kidney.
In April, surgeons at New York City-based NYU Langone Health performed the world's second pig kidney transplant and the first procedure to include a pig's thymus gland to aid against rejection. The procedure also represented the first combined mechanical heart pump and organ transplant surgery, with the patient receiving the kidney eight days after receiving a mechanical heart pump. The patient, Lisa Pisano, had the kidney removed 47 days after surgery because it was damaged by inadequate blood flow from the heart pump. Ms. Pisano, who had both heart and kidney failure, died in July.
The most recent milestone occurred in November, when NYU Langone surgeons successfully implanted a pig kidney with 10 gene edits into a female patient with chronic kidney disease. The patient is visiting the health system daily for evaluations and expects to return to her home state of Alabama within three months.
While the field of xenotransplantation is still in its infancy, today's innovations are built on decades of research. The roots of xenotransplantation date back to the 1960s when immunosuppressive drugs were first developed, and researchers began exploring their potential to prevent organ rejection, according to the National Kidney Foundation. Researchers initially transplanted organs from nonhuman primates into patients, though these attempts were unsuccessful. It wasn't until the 1990s that researchers identified pig organs as a better option because they are widely available and anatomically similar to human organs.
The FDA allows for animal organ transplants for patients with life-threatening conditions who are too sick to receive human organs under its compassionate use or expanded access program.
These pioneering efforts mark a turning point in transplant medicine, offering hope to thousands of patients and families facing the uncertainty of organ shortages. More than 100,000 people in the U.S. are on the waiting list for an organ transplant, and 17 people die each day waiting for an organ.
Xenotransplantation has emerged as a potential solution to the global organ shortage, particularly for kidneys, which are the most common organ needed for a transplant. As researchers continue to refine these techniques, the field edges closer to making animal-to-human transplants a routine and life-saving option.