A world-first: genetically modified pig kidneys have functioned normally and without rejection in a human trial. It’s another step toward xenotransplantation, a longtime dream of doctors hoping to solve the problem of organ failure in humans.
Genetically modified pigs
A kidney from a pig was successfully transplanted in a recently deceased patient whose family had given consent. The kidney was able to function for three days, performing its filtration and urine production functions perfectly and without rejection, said on October 20th the team led by Professor Robert Montgomery, who performed the operation at New York’s Langone Health Center.
The kidneys were removed from the animal, which had been genetically modified to remove a gene that produces Alpha-gal, a sugar not found in humans and which normally causes animal transplant rejection. The pig, produced by United Therapeutics, was approved by the Food and Drug Administration (FDA) in December 2020.
For three days, the kidney was implanted into blood vessels and kept out of the body. “The patient’s creatinine levels returned to normal immediately after the transplant, indicating that the kidneys were functioning properly,” says Professor Robert Montgomery. This was even better than with some kidneys harvested from deceased humans.
Twelve people die every day in the US waiting for a kidney
“More than half of dialysis patients deteriorate severely or die before they can be transplanted,” says Montgomery, who himself recently received a heart transplant. “I know what it’s like to be uncertain about when an organ will be available”. There are 90,000 people waiting for a kidney transplant in the United States, and a dozen die every day because they don’t get it in time. According to Robert Montgomery, this experiment could lead to actual transplants for patients with advanced kidney disease within a year or two.
Decades of progress in xenotransplantation
Xenotransplantation (interspecies transplants) is an old dream of doctors hoping to raise animals to be organ donors. The first real attempt took place in 1984 when a baby nicknamed “Baby Fae” survived for 21 days with a baboon heart. Since then, research has evolved and doctors have focused more on pigs because they are easy to raise, grow quickly, and have human-like organs. In addition, their use as donors raises fewer ethical issues than, for example, primates.
In humans, pig heart valves, tendons, pieces of skin, and retinas are already used as temporary or permanent transplants. But Dr. Robert Montgomery’s operation shows that healthy organs can also be successfully transplanted, which could pave the way for other types of transplantation. In 2018, a baboon lived for six months with a pig’s heart.
However, there are still many uncertainties surrounding this new technique (the details of which have not yet been released). First of all, we need to ensure that the transplant is viable in the long term. There are also fears that xenografts can facilitate the transmission of viruses from pigs to humans. But for Robert Montgomery, this risk is less than the risk of letting patients awaiting transplantation die and deteriorate rapidly.