Life-saving transplants are often curtailed by shortage of human donor organs but this problem could possibly be addressed in the future as researchers discovered a way to make pig organs suitable for use in people.

Researchers used a gene editing technique to modify pig organs so they become better matches for human transplants.

While whole pig organs are functionally similar to human organs, they cannot be used as replacement because of possible transmission of latent retroviruses that do not cause harm in pigs but could lead to illness in people.

Harvard University geneticist George Church and colleagues used a method called CRISPR-Cas9, which works like a molecular scissors that can trim select parts of a genome. Using this technique, the researchers were able to remove native pig viruses that prevent the animal's organs from being used for transplants in humans.

In experiments involving early pig embryos, the researchers used CRISPR to remove 62 copies of porcine endogenous retroviruses (PERVs), which are embedded in the genomes of the pig and cannot be treated or neutralized. PERVs could potentially cause disease in human transplant recipients.

The researchers found that the modified pig cells did not easily pass the retrovirus to human cells.

"It was kind of cool from two stand points," said Church, who co-founded eGenesis, a biotech company that wants to produce modified pigs for organ transplantation. "One is it set a record for Crispr or for any genetic modification of an animal, and it took away what was considered the most perplexing problem to be solved in the xenotransplantation field."

The research, however, has limitations. While Church and his team have shown that it is feasible to edit the genome of pigs, they were unable to show that these organs would already be safe for use in people.

Still, the researchers believe that the technology will pave way for pig organs being used as substitute for human organs where no suitable donor organs could be found for patients who need a transplant. To date, most donor organs primarily come from deceased donors.

"Our study shows that CRISPR-Cas9 multiplexability can be as high as 62 and demonstrates the possibility that PERVs can be inactivated for clinical application to porcine-to-human xenotransplantation," the researchers reported in their study, which was published in the journal Science on Oct. 11.