It's not the usual way that reputable scientists announce their breakthroughs to the world, but on Monday, Jiankui He released a video proclaiming that he produced the world's first human babies whose genomes were edited using a powerful technique called CRISPR. He had also previously spoken to the Associated Press about his study, which he says resulted in twin girls born with the first genomes edited by man.
The report was met with instant concern and skepticism by the scientific community. He's experiment altered the genomes of embryos produced through IVF; their genetic changes will therefore be passed on to any future generations. What's more, most experts in CRISPR are not convinced that the technology is ready-or safe-for treating humans.
"Given the current early state of genome editing technology, I'm in favor of a moratorium on the implantation of edited embryos … until we have come up with a thoughtful set of safety requirements first," Feng Zhang, one of the co-discoverers of CRISPR and from the Broad Institute of MIT and Harvard, said in a statement responding to the report. "Not only do I see this as risky, but I am also deeply concerned about the lack of transparency surrounding this trial."
In 2015, prominent members of the scientific community familiar with the technology, including Zhang and another co-discoverer, Jennifer Doudna from the University of California, Berkeley, agreed to voluntarily stop researching the use of CRISPR in human embryos because of the safety and long term consequences of the technology was too uncertain. The researchers support studies in which CRISPR is used to develop treatments that would affect cells that are not passed on to the next generation – i.e. anything except egg and sperm – but say that more research is needed before CRISPR is used to make changes in genomes that can be carried by generation after generation.
While editing the DNA of a human embryo is currently not allowed in the US, in 2017, an international committee of the National Academy of Sciences called for a loosening of the moratorium and allowing trials of CRISPR in human embryos, under strict supervision, to treat rare genetic diseases that can not be addressed in any other way. In the U.K., officials approved studies of CRISPR in human embryos in 2016, but those embryos will not be transplanted to create pregnancy. These trials call for the destruction of embryos after a week, as technology's safety remains unclear.
He, on the other hand, has apparently jumped ahead to producing the first human babies born with CRISPR editing. He is a professor at the Southern University of Science and Technology in Shenzhen China, but in a statement released in response to He's videos, the university said he was on unpaid leave from February 2018 to January 2021; officials did not provide a reason for the leave.
"The University was deeply shocked by this event and took immediate action to reach Dr. Jiankui He for clarification, "the officials said in the statement. "The research was conducted outside the campus and was not reported to the University nor the Department [to which He belongs]. "The statement went on to note that the university" believes that Dr. Jiankui He's conduct in using CRISPR / Cas9 to edit human embryos has seriously violated academic ethics and codes of conduct … The University will call for international experts to form a independent committee to investigate this incident, and to release the results to the public. "
CRISPR, first described in 2012, gives scientists the most accurate and effective way to edit the human genome by sniping out offending mutations or gene and either allowing the genome to repair itself or providing researchers with the ability to insert new genetic material to correct disease gene . But studies suggest that controlling CRISPR in human cells remains a challenge; in some cases CRISPR may cut unintended parts of the genome.
In his promotional video, He describes targeting the CCR5 gene, which helps the HIV virus enter healthy human cells. He worked with seven heterosexual couples in which male partner was HIV positive and women were HIV negative. After the couples produced embryos through IVF, he used CRISPR to cut the CCR5 gene, disabling it in the hopes of making the embryos less vulnerable to HIV infection. He claims that of 22 embryos, 16 showed signs of successful CRISPR editing, and 11 were implanted, resulting in a single pregnancy with twin girls who were born in November. One twin, according to He's tests, showed signs that both copies of the CCR5 genes he inherited (one from his mother and one from his father) were successfully altered, while the other twin showed that one version of the genes it inherited was altered.
This so-called mosaicism, in which some but not all of the embryo's cells are altered, is troubling since in this case, it would mean that the girl may not be completely protected from HIV infection like her sister. That's one of the reasons why researchers are concerned about the report. Normally such scientific milestones are reported in scientific journals complete with detailed descriptions of how the researcher accomplished the feat along with data supporting their claims. Without such documentation, it is impossible to verify whether the girls really showed successful CRISPR editing or not.
He, who created two companies based on his studies, is scheduled to present his findings at the Second International Summit on Human Genome Editing, and will surely be the target of many questions from the leading genetic editing scientists in attendance.