(CNN) — Pigs may someday provide organs for human transplant surgeries, yet more than a few obstacles must be overcome first.

Using the genome-editing technology CRISPR, scientists deactivated a family of retroviruses within the pig genome overcoming a large hurdle in the path to the transplant of pig organs into humans.

Transplantation from one species to another — xenotransplantation — holds “great promise,” the American and Chinese research team believes.

“Porcine organs are considered favorable resources for xenotransplantation since they are similar to human organs in size and function, and can be bred in large numbers,” they wrote in a study published Thursday in the journal Science.

Retroviruses carry their genetic blueprint in the form of ribonucleic acid (or RNA) and transcribe this into deoxyribonucleic acid, commonly known as DNA. This is a reverse of the usual transcription process, which flows from DNA to RNA. This reversal makes it possible for retrovirus genes not only to infect cells but to become permanently incorporated into a cell’s genome.

In particular, the pig genome is known to carry porcine endogenous retroviruses (or PERVs), which are capable of transmitting diseases, including cancers, into humans. The presence of these PERVs means pig organs cannot now be safely transplanted into humans.