Researchers from a biotechnology startup eGenesis and several universities in China, Denmark and the United States, have used CRISP-Cas9 gene editing techniques to remove diseases that could be transmitted from pigs to humans during tissue transplants.
Before these kinds of transplants are allowed, other genetic changes may need to be made to pigs, and regulators will require tests using lab primates prior to using genetically engineered organs in humans.
A peer-reviewed paper on the research was published Thursday in the journal Science.
But a breakthrough using CRISPR gene editing technology paves the way for pigs free of PERVs.
Dr. David Klassen told The New York Times that if pig organs were safe and effective to transplant into humans "they could be a real game changer". As a result, Church had wondered if they play an essential role in the pig's survival and whether the animals could develop properly without them.
"This is the first publication to report on PERV-free pig production", Luhan Yang, co-founder and chief scientific officer at eGenesis, said in a press release. "We are pushing the envelope of technology day by day".
"We will continue to use this platform to engineer the pig genome, on the basis of PERV-free pigs, to enhance pig-to-human immunological compatibility for the clinical xenotransplantation of porcine organs as early as possible", she said. While most major religious groups say pig organs are acceptable in the case of lifesaving transplantation, one example that could be a problem for Jewish and Muslim patients is accepting a kidney transplant, because dialysis is a viable alternative. The same year, they showed that CRISPR could knock out PERV genes at all 62 sites in the pig genome-the most widespread CRISPR editing feat to date. These PERVs have the potential to infect humans if a pig organ is transplanted into a person, possibly causing tumors or leukemia.
Genetics expert Professor Darren Griffin, from the University of Kent, said: "This represents a significant step forward towards the possibility of making xenotransplantation a reality".
There are now more than 100,000 people in the United States awaiting organ transplants, and only 20 to 30 percent of them will ever receive one, she said. eGenesis, based in Cambridge, Massachusetts, is entirely focused on furthering xenotransplantion as a viable option. And even with PERVs off the table, pigs will require other modifications so that their organs won't be rejected by the human immune system or cause other harms. However, pigs also have many viruses embedded in their DNA, passed down the generations in sperm and eggs. Remnants of ancient viral infections, genes from porcine endogenous retroviruses-known by their unfortunate acronym-are scattered throughout the pig genome, and could infect a person who one day receives a pig's heart, lung, or kidney as a replacement or temporary organ.