A group of researchers in Oregon has become the first in the US to try to genetically modify human embryos, as reported by MIT Technology Review. The effort is said to represent an advance in the safety and efficacy of methods used to correct the genetic defects that cause the disease.
So far, only three published reports of human embryo gene editing have come from researchers in China. But their experiments—using a gene-editing technique called CRISPR—caused “off-target” genetic mutations, mutations in unintended DNA. Also, not all cells in embryos are successfully reproduced, causing an effect called “mosaicism.” Together, the problems suggest that the technique is not advanced enough to safely modify human embryos without unexpected or inaccurate genetic results.
Scientists familiar with the new US work told MIT Technology Review that the Oregon team has advanced these issues. They say they have shown in trials with “several tens” of human embryos that they can correct disease-causing genetic mutations while avoiding mosaicism and off-target effects. Their improved method allows for early delivery of CRISPR into cells at the same time sperm fertilize an egg.
A team of researchers, led by Shoukhrat Mitalipov of the Oregon Health and Science University, created embryos using the sperm of men with inherited mutations that cause a disease. But it is not clear what disease or genes are edited. None of the embryos were allowed to develop for more than a few days and were not intended for implantation.
When you reach MIT Technology Review, Mitalipov declined to comment on the results, which he said were pending publication.
An unnamed scientist who is familiar with the work cited MIT Technology Review that it is “proof of a viable principle. They significantly reduce mosaicism. I don’t think it’s the start of clinical trials yet, but it’s taken further than anyone has before.”
The report follows a report earlier this year by the National Academy of Sciences and the National Academy of Medicine, which gave the green light to researchers to use gene editing to treat or prevent inherited disease. The report—written by 22 of the world’s leading professors of genetics, ethics, medicine, and law—cautions though, recommending that the technique be used only under strict supervision. with extreme caution, and when all other options have been exhausted. The committee opposes any attempts to create “model offspring” or use mass breeding for anything other than disease eradication.
Scientists have long feared that such gene-editing technology could be used for nefarious or questionable purposes. In the US, no clinical trials with edited human embryos are currently allowed to proceed. However, there are many countries without such legal restrictions.