WASHINGTON - Scientists seeking to make pig organs safe enough to transplant into humans have used gene-editing technology to clone piglets that lack a potentially dangerous retrovirus, according to a study released on Thursday.

The breakthrough, according to authors of the study published in the journal Science, could help pave the way for transplantation of whole pig organs into humans, without fear of patients being infected with the pig retrovirus. But other hurdles remain.

Transplants from pigs could offer a new potentially lifesaving alternative for patients diagnosed with organ failure and no other viable treatment options. A shortage of available human organs has led scientists to study the possibility of animal donors to close the gap.