Pig hearts could soon be tested in humans after scientists passed an important milestone when transplanting the organs into primates.

In 2000, the International Society for Heart and Lung Transplantation (ISHLT) suggested that human trials would be considered once 60 per cent of primates could live for three months, with at least some indication that longer survival was possible.

Previous studies have only achieved up to 57 days survival, so the new research is the first to meet the criteria set out by the ISHLT, and represents a major step in the clinical use of pig hearts in humans.

Now surgeons in Germany, using hearts from pigs that had been genetically modified to remove threatening viruses and prevent the body rejecting the foreign organ, have grafted the hearts into five baboons and kept four of the animals alive for at least 90 days, with one still in good health for more than six months.

Writing in the journal Nature, cardiac surgeon Bruno Reichart, of Ludwig Maximilian University of Munich, said they had proved that transplanting hearts worked in one of human’s closest relatives, and that 195-day survival was a ‘milestone’ in using the procedure in the clinic.

British scientists said that the government, NHS and the Human Tissue Authority should now look at how to regulate and fund operations.