First editing of human embryos carried out in United States
U.S. scientists have for the first time altered the genes of human embryos — a controversial step toward someday helping babies avoid inherited diseases.
Researchers at Oregon Health and Science University (OHSU) in Portland believe they have broken new ground both in the number of embryos experimented upon and by demonstrating it is possible to safely and efficiently correct defective genes that cause inherited diseases, according to MIT Technology Review, which first reported the news Wednesday.
It is thought to be the first such work in the U.S.; scientists in China have published similar studies with mixed results.
None of the embryos were allowed to develop for more than a few days, and they were never intended for implant into a womb, according to the report.
Results of the peer-reviewed study are expected to be published soon in a scientific journal, according to OHSU spokesperson Eric Robinson.
The research, led by Shoukhrat Mitalipov, head of OHSU’s Center for Embryonic Cell and Gene Therapy, involves a technology known as CRISPR that has opened up new frontiers in genetic medicine because of its ability to modify genes quickly and efficiently.
CRISPR works as a type of molecular scissors that can selectively trim away unwanted parts of the genome and replace them with new stretches of DNA.
Permanent genetic changes
The approach holds great potential to avoid many genetic diseases but has raised fears of “designer babies” if done for less lofty reasons, such as producing desirable traits.
Furthermore, with germline gene editing (sperm, eggs or embryos), the changes are permanent and could be passed down to any offspring, and that’s of concern to Canadian researcher David Edgell, an associate professor of biochemistry at the University of Western Ontario.
“If you introduce an unwanted consequence, then unfortunately that person has that unwanted consequence forever because it’s now in their germline tissue,” he said in an interview with CBC News. And they can pass it on to their children and their children’s children.
CRISPR has a well-documented unpredictability in hitting its intended target — what Edgell calls “the GPS problem.” He’s interested to review the data and see how well the researchers overcame the problem.
“How confident are you? Are you 99 per cent sure? Are you 99.9 per cent sure?” said Edgell, who was part of a UWO team that developed a CRISPR variant that’s more precise at reaching its desired location.
“Apart form the whole ethical, religious, legal debate about whether or not we should even be doing this,” he said, “it’s the technical problem of the accuracy.”
In December 2015, scientists and ethicists at an international meeting held at the National Academy of Sciences (NAS) in Washington said it would be “irresponsible” to use gene editing technology in human embryos for therapeutic purposes, such as to correct genetic diseases, until safety and efficacy issues are resolved.
But earlier this year, the expert committee softened its position, saying in its report that scientific advances make gene editing in human reproductive cells “a realistic possibility that deserves serious consideration.”
Dr. Janet Rossant, a senior scientist at the Hospital for Sick Children in Toronto, was on the committee, and she says there were lots of caveats attached.
“What we did say is there would have to be clear delineation of the boundaries of these approaches,” Rossant told CBC News.
For instance, gene editing for “enhancement” (like muscle building) should not be allowed. And clinical trials should be allowed only for “compelling purposes of treating or preventing serious disease or disabilities, and only if there is a stringent oversight system able to limit uses to specified criteria.”
Rossant notes that OHSU’s research would not be allowed in Canada: the Assisted Human Reproduction Act bans any manipulation of the human genome that can be transmitted to the next generation.
Edgell said research like OHSU’s is “necessary proof of principle” to determine the feasibility of this kind of therapy, and it’s appropriate as long as regulatory guidelines are “strictly followed.”
“Is it ethically wrong to avoid these technologies if they can actually improve someone’s well-being?”
