Lab tests show risks of using CRISPR gene editing on embryos
A laboratory experiment to diagnose faulty DNA in human embryos reveals how this method of gene editing is incorrect and why leading scientists claim that it is too insecure to pursue.
The editing produced unexpected modifications in more than half of instances, such as a lack of a whole chromosome or of broad bits.
Researchers from Columbia University explain their study in the Cell newspaper on Thursday.
They used CRISPR-cas9, the same chemical weapon which a Chinese scientist used on embryos in 2018 to render the first geneally engineered kid in the world to get him to jail and draw foreign contempt.
This technique helps scientists to cut their DNA reliably and has tremendous potential for good — it's being used to grow healthier crops and animals, hopes to cure diseases, and received a Nobel Prize earlier this month.
But it makes variations to embryos, semen and eggs that will transfer through future generations.
Several science and ethicist international committees have suggested it is too early to determine if this can be achieved safely, and the recent work in Columbia indicates potential harm.
"When our findings were known two years earlier, it would be a doubt for everyone," said biologist Dieter Egli, who performed the research, and tested it on embryos meant for pregnancy.
Researchers produced 40 embryos with good donor eggs and a man's sperm with gene mutation — a single letter absent in the DNA alphabet — resulting in blindness.
The object of editing was to introduce the missing letter so that the gene functions.
In certain eggs, fertilization was attempted, and it was found the right time to do so.
When two cells were enclosed and almost two days old, other embryos were edited.
At different levels of growth cells were then examined to see how many had reversed the mutation.
Surprisingly, none of the embryo cells edited during fertilization operated.
It function only in three of the 45 embryo cells, which were edited later.
In certain instances, "What we have discovered is that the chromosome that contains the mutation is gone instead of the mutation," — a profound improvement that is unlikely to hurt the embryo, "Egli said.
Former researchers thought they had reversed an embryo deficiency might have been mistaken because the common lab studies have no longer identified the mutation. However, more tests, such as that performed in that report, indicate that other modifications, such as the scraping of the whole chromosome, may have occurred. Egli said. Egli said:
The latest research indicates that gene editing might have a promise to rectify conditions induced by a duplicate of the additional chromosome, including Down syndrome. But, Dr. Eric Topol wrote in an email "furthermore, we are not able, not even near."
Topol, who is Head of the Scripps Research Translation Institute of San Diego and did not play any part in a new work, added: "This brings the questions already voiced on human embryo editing to another stage.
In the United States , government grants can not be used for human experimentation on embryos, but Columbia researchers have been utilizing private funding from two foundations.
The Related Department of Press Health and Research is funded by the Department of Science Education of the Howard Hughes Medical Institute.