double muscle pigs
Scientists manage to edit pig DNA to make organs suitable for human transplant Nick Saltmarsh

Scientists in the US have managed to identify a new gene-editing technique that can remove potentially harmful DNA from the pig genome, which will allow them to use the animals' organs for human transplants. A technique named CRISPR was used by Harvard University scientists to eliminate potentially harmful DNA sequences at 62 locations within pigs.

The locations are the fragments of a virus called porcine endogenous retrovirus (PERV) within the pig genome, which is dangerous to humans. "The presence of this type of virus found in pigs... brought over a billion of dollars of pharmaceutical industry investments into developing xenotransplant methods to a standstill by the early 2000s," senior author George Church, a geneticist at Harvard University, said in a statement.

"PERVs and the lack of ability to remove them from pig DNA was a real showstopper on what had been a promising stage set for xenotransplantation," he added. However a study, published in Science, details how the scientists have managed to remove the DNA so animal organs are ready for human transplants, a notion known as xenotransplantation.

Church and his colleagues made 62 genetic edits within the pig DNA to the inactive virus – which is not harmful to pigs. They described the new technique as "an explosive leap forward in CRISPR's capability when compared to its previous record maximum of just six simultaneous edits". When the cells were then introduced to a human host, the researchers state, the PERV infectivity rate was down by 1,000 fold.

Lead author Luhan Yang, a postdoctoral fellow at the Harvard University, added: "Our work dispelled the shadow PERVs cast on the field more than a decade ago when the virus was discovered, while renewing our faith in xenotransplantation."