Scientists have created gene-edited piglets free of viruses that might cause disease in humans, in a striking breakthrough that could open the door to organ transplants from animals.

The experiments, reported on Thursday in the journal Science, may make it possible to transplant livers, hearts, and other organs from pigs into humans, The New York Times reports.

Dr. David Klassen, chief medical officer at the United Network for Organ Sharing, a private, nonprofit organization that manages the nation’s transplant system, said the advance “could be a real game changer.”

About 33,600 organ transplants occurred last year, with 116,800 patients on waiting lists, according to Klassen, who was not involved in the new study.

“There’s a big gap between organ supply and organ demand,” he told The Times.

Dr. George Church, a geneticist at Harvard University who led the experiments, said the first pig-to-human transplants could occur within two years.