In the 1990s, researchers explored the likelihood of using pig organs in humans, a technique known as xenotransplantation. Experts hoped that pig organs could be cleansed of viruses and other pathogens that might harm their human hosts. That research stalled in 1998, when Jay Fishman and his colleagues discovered a strange new danger.
Pig cells contain multiple copies of embedded viruses called porcine endogenous retroviruses, or PERVs. PERVs can produce full-blown viruses able to infect other pig cells. When researchers mixed pig and human cells, they found the pig viruses could also contaminate human cells; causing cancer or other diseases.
Recently developed methods for editing genes could make pig organs safe for human transplant.
Among the scientists describing the recent scientific advances was one of Crispr’s pioneers, George Church of Harvard Medical School. Dr. Church’s experiment had its origins in the shortage of available human organs for transplants. Thousands of people die each year waiting for hearts, lungs and livers.
“It’s a cruel situation currently, that someone who needs a heart transplant has to pin their chance for a healthy life on the untimely death of another person,” said David A. Dunn, an expert on transplantation at the State University of New York at Oswego.
In a typical experiment, scientists used Crispr to alter a single gene. But in recent work with pig cells, Dr. Church and his colleagues used Crispr to simultaneously disable all 62 of the viruses. The team engineered a new set of genes that produced enzymes that hunted for PERVs and snipped out bits of the viral DNA.
After the experiment, the viruses in the pig genome showed little activity. And despite the drastic genomic surgery, the chromosomes showed no irregularities and the cells grew normally.
The researchers hope that this achievement may someday make it possible to use pig organs for transplantation into humans, which will reduce the amount of deaths per year of people waiting for available organs for transplant.
We should assume and expect scientists to promptly develop their gene editing skills in the years to come.