A team of researchers claims that they successfully edited the genomes of human embryos using a gene-editing technique known as CRISPR-Cas9. Chinese scientists had already used the technique to modify human embryos, although this appears to be the first time U.S. scientists achieve it.

CRISPR stands for “clustered regularly interspaced short palindromic repeats,” and is a molecular tool that combines RNA molecules and individual proteins to cut and edit DNA.

Image Credit: Getty Images / Popular Mechanics
Image Credit: Getty Images / Popular Mechanics

The team was led by Shoukhrat Mitalipov at the Oregon Health & Science University’s Center for Embryonic Cell and Gene Therapy. The feat raised skepticism from several members of the scientific community, who view the achievement as “unethical,” and which one day could lead to people “editing” their babies at their own will.

U.S. scientists reportedly edited human embryos to write off inherited diseases

The CRISPR technique was discovered five years ago, and it’s been used in a variety of studies. Recently, a group of scientists encoded an old racehorse movie into bacteria DNA using the technique, which led them to believe CRISPR could one day be used to study the molecular history of the brain. Furthermore, three studies conducted by Chinese scientists reported editing human embryos using CRISPR.

But the new achievement by Mitalipov and his team sets aside from the previous Chinese studies, as they used a higher number of embryos, and they proved that it’s possible to correct defective genes that cause inherited diseases.

“So far as I know this will be the first study reported in the U.S.,” said Jun Wu, a scientist at the Salk Institute in La Jolla, who also worked on the new project, according to MIT Technology Review.

The researchers said none of the embryos were allowed to develop for more than a couple of days, and stressed that they did not intend on implanting them into a womb. With their findings, the scientists expected to show they can correct or eliminate genes that cause some inherited diseases. The process is known as “germline engineering.”

Cover art for the latest MIT Technology Review. Image Credit: MIT / Contrary Brin
Cover art for the latest MIT Technology Review. Image Credit: MIT / Contrary Brin

However, some experts believe germline engineering could one day lead to “designer babies” that would be engineered not only to avoid inherited diseases but to have more intelligence or athletic skills, thus creating genetically enhanced humans. MIT Technology Review reports that last year, the U.S. intelligence community even called CRISPR a potential weapon of mass destruction.

Mitalipov declined to comment on the results to MIT Technology Review, as the study is still pending publication. However, other researchers confirmed the Oregon University team edited embryos using CRISPR-Cas9.

National Institutes of Health won’t fund experiments that modify human embryos

CRISPR was partially funded by the National Institutes of Health. However, the organization has made clear it will not support any research that uses gene-editing technology, such as CRISPR, to modify human embryos. In a press release two years ago, NIH noted that while they fund research that uses the technique to help eradicate diseases, it will not support editing human embryos.

“The concept of altering human germline in embryos for clinical purposes has been debated over many years from many different perspectives and has been viewed almost universally as a line that should not be crossed,” Francis Collins, Director of NIH, said in a statement dated April 28, 2015. “Advances in technology has given us an elegant new way of carrying out genome editing, but the strong arguments against engaging in this activity remain.”

The statement stressed NIH’s position against the activity includes the serious and unquantifiable safety and ethical issues that present by altering the germline in a way that affects coming generations without their consent, as well as the “lack of compelling medical applications” justifying the use of gene-editing technology in embryos.

Ethicists fear that germline engineering will pave the way to the "designer babies" industry. Image Credit: Shutterstock / OurSundayVisitor
Ethicists fear that germline engineering will pave the way to the “designer babies” industry. Image Credit: Shutterstock / OurSundayVisitor

In February this year, an advisory committee from the National Academy of Sciences announced their support for using CRISPR to edit genes of embryos in order to remove DNA sequences that cause inherited diseases.

Oregon University team found a way to avoid ‘mosaicism’ when editing human embryos

The previous Chinese studies on modifying human embryos had concluded that CRISPR caused some editing errors and that the targeted DNA changes did not show in all of the embryos, only in some. That effect is known as mosaicism.

However, Mitalipov and his team said they found a way to avoid mosaicism. A scientist involved in the study told MIT Technology Review that tens of human IVF embryos were developed for the experiment using donated sperm of men with inherited disease mutations.

“It is proof of principle that it can work,” the unidentified scientist told MIT Technology Review. “They significantly reduced mosaicism. I don’t think it’s the start of clinical trials yet, but it does take it further than anyone has before.”

The scientist told the publication that Mitalipov’s team appears to have avoided earlier difficulties like mosaicisms by “getting in early” and using CRISPR on the eggs at the precise time of fertilization with sperm. However, the team has still to publish their findings, and further research is necessary to assess the pros and cons of genetically editing human embryos.

Source: MIT Technology Review