Pig hearts were transplanted into baboons – a development that could pave the way for people to get pig organs in the future.
Researchers from Germany, Sweden and Switzerland reported that two Anubis baboons survived half a year, while two more lived at least three months.
Previously, the baboon survived the longest 57 days after such a procedure.
Since then, genetic changes have been made to the heart and a new transplantation technique has been developed.
The pigs were modified to produce a human version of two proteins that block an immune response in alien cells.
It was also ensured that they generated thrombomodulin, which prevents blood clotting after surgery.
The research team also stopped preserving the donor hearts in the cold store and instead kept them at 8 ° C.
They circulated fluids that contained oxygen, hormones, red blood cells, and nutrients.
The baboons were given medicines to prevent the pig's heart from getting too big and lowering their blood pressure to match that of the pigs.
The transplant procedure was refined in three experiments with 14 baboons.
One of the five baboons in the last experiment had to be discontinued after the development of a blood clot.
Transplantation of an organ between two different species – known as xenotransplantation – is seen as a way to overcome an organ deficiency for people in need of a transplant.
The results of the scientists were published in the Nature Journal.