New gene-editing research could pave the way for safe organ transplants between pigs and humans in the future. In a study published in Science this week, geneticists said they removed a number of potentially harmful DNA sequences from pig cells thought to be harmful to humans. These sequences, some of which produce porcine endogenous retroviruses, or PERVs, present one of many barriers for transplanting whole organs from pigs to humans. "Basically, this whole field has been in the doldrums for 15 years," George Church, the study's lead researcher, told Science. "There’s been kind of a few true believers that had it on life support. But I think this changes the game completely."
22 people die every day in the US waiting for organ transplants
Pig-to-human transplants are part of a field known as xenotransplantation, and are thought to be one of the best solutions to the dire shortage of organ donors worldwide. At the moment, there are more than 122,000 individuals in the US in need of a life-saving organ transplant, with 22 people estimated to die every day on the waitlist. To date, pig tissue and even valves have been transplanted into humans, but not whole organs, due to the danger of life-threatening immune responses from the host's body.
The new study is also being hailed by some as a step forward for CRISPR, a successful gene editing technique that has been used to change even the genetic code of non-viable human embryos. Church and his team made as many as 62 cuts in a single pig genome, 10 times more edits than have previously been achieved using CRISPR. However, Church did note that removing the same sequence of DNA from a single genome multiple times is not the same as targeting lots of different, unique genes. "We’re not convinced that what we did is generalizable," Church told Science. "It doesn’t mean that we can now change 62 different genes easily."
Deactivating PERVs and other potentially harmful genes in pig DNA should help with the ultimate goal of transplanting pig organs into humans, but there are still many difficulties to overcome, not least of all applying these techniques to viable embryos and not just cells. Church has co-founded a private biotech company called eGenesis to work on this and other problems, and told Nature that his company is ready to implant edited pig embryos into potential mother pigs.