The field of xenotransplantation – implanting organs from one species into another – has accelerated dramatically since the discovery of the CRISPR gene editing tool a few years ago. Hurdles that previously seemed insurmountable are now not so daunting. The latest landmark development in the field comes from a team of scientists who successfully created genetically modified piglets free of 25 retroviruses that are generally present in pigs but thought to cause harm to humans.
There are several obvious problems scientists must overcome before successfully being able to transplant pig organs into humans. Despite pig organs posing as prime candidates for human transplantation considering their similar size and function, they generally, and unsurprisingly, trigger significant immune rejection responses in humans.
This first problem is being tackled by several scientists including pioneer transplant researchers Joseph Tector and David Cooper, both currently based at the University of Alabama at Birmingham. Both scientists have made major breakthroughs in identifying key genes in pigs that trigger human immune rejections. Using CRISPR they created pigs with those key genes suppressed and believe human trials using these implanted pig organs could begin soon.
The other major problem scientists face in implanting pig organs into humans is the widespread presence of certain retroviruses in the animals. Called Porcine Endogenous Retrovirus (PERV), these viruses are remnants of ancient viral infections and are harmless in pigs but many believe they could pose a threat when transferred to human systems, particularly when considering the immunosuppressed status of a transplant patient.
This latest breakthrough made by researchers from Harvard and Massachusetts-based company eGenesis involves successfully deploying CRISPR to engineer healthy piglets that are entirely free of PERVs. The research identified and deactivated 25 genomic triggers known to activate PERVs, allowing surrogate sows to then be successfully implanted with PERV-free embryos and giving birth to piglets free of the endogenous viruses.
It's undeniable that CRISPR is accelerating the pace of research in the realm of xenotransplantation. On top of research from earlier this year displaying success in creating a human-pig chimera, it is becoming increasingly clear that we may very well soon crack the challenge of human-animal organ transplantation.
The new PERV-free pig research was published in the journal Science.