Enlarge / One of the PERV-free piglets.
They also gave insulin-producing islet cells from a pig to diabetic monkeys, and the monkeys lived for a year without requiring insulin.
The pigs are going to save us. The retroviruses, which are passed on through hog generations, have never proven to transmit to humans-no human PERV disease cases have ever been reported, even in patients who have received pig tissue transplants.
For decades, scientists have been pursuing the idea of pig transplants.
A peer-reviewed paper on the research was published Thursday in the journal Science.
The adult cells were not as nature made them, however.
In a step toward making pig organs safe for human transplant, scientists at Egenesis Bio Inc. have used multiplexed CRISPR editing to remove porcine endogenous retroviruses (PERVs) from pigs. In most of the rest, CRISPR missed its mark.
The National Health and Medical Research Council (NHMRC) code for the care and use of animals for scientific purposes states that all teaching and research activities "must balance whether the potential effects on the wellbeing of the animals involved is justified by the potential benefits". The projects took were complicated and costly and many animal right activists started targeting the Gene Editing scientists. "That can happen when you make two or three [CRISPR edits], and we're dealing with 25". It's too early to say if this group has a higher death rate than normal, because piglets often die from infections, says collaborator George Church of Harvard University.
Despite this feat, however, cloning the modified cells resulted in only 90% continued PERV-free generation - a good result, but not good enough for risk-free transplantation. But with a genome wiped of active viruses, the researchers produced 37 piglets that are PERV-free. Not all were brought to term, and some were killed so the scientists could check how their organs were developing, but today, 15 piglets are still alive.
Among eGenesis's next experiments: see if the pigs are fertile and, if so, whether their CRISPR'd genetic changes, including inactivating PERVs, are inherited.
Organ transplantation is a controversial topic at the best of times.