The modification of 60 genes was ten times more than have ever been previously edited in any animal. This was accomplished by using CRISPR gene-editing technology to inactivate 62 porcine endogenous retroviruses (PERVs) in pig embryos. The group also modified more than 20 genes in a separate set of embryos. Among these was a gene that encodes for proteins that sit on the pig cell and cause blood clotting or triggers an immune response in humans.
Eventually the pigs that will be used to grow organs for humans will have both of the modifications as well as the deletion of PERV. Although the edited embryos are not yet ready to be implanted into the mother pig, Church believes they are close. The organ donor pigs will be kept in isolation away from pathogen. I found this article to be very interesting. It is impressive that they were able to edit that many genes and still produce good results. This could lead to many benefits in the future, especially in human therapies.