U.K. Scientists Given the Go-Ahead to Edit Genomes of Human Embryos

For a country this powerful to start editing viable human embryos sends a clear signal to other countries: they, too, could follow suit.

A major scientific institution in London has received the green light from the U.K. Human Fertilization and Embryology Authority (HFEA) to use the genome-editing technique CRISPR–Cas9 in healthy human embryos.

In April, Chinese scientists quietly published a game-changing paper in which they reported that, for the first time, they’d edited a non-viable human embryo using CRISPR-Cas9. But now, a team led by developmental biologist Kathy Niakan of the Francis Crick Institute in London plans to alter active genes in viable human embryos donated by patients who had undergone in vitro fertilization.

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A human embryo at day four

Niakan’s team hopes to gain more insight into early development, with the long-term goal of developing a treatment for infertility. Miscarriages and infertility are both fairly common, but they’re still not well-understood. Niakan plans to stop editing embryonic genes after seven days, after which the embryos will be destroyed.

Here’s Ewen Callaway, reporting for Nature News:

At a press briefing last month, Niakan said that her team could begin experiments within “months” of the HFEA approving the application. Its first experiment will involve blocking the activity of a ‘master regulator’ gene called OCT4, also known as POU5F1, which is active in cells that go on to form the fetus. (Other cells in the embryo go on to form the placenta). Her team plans to end its test-tube experiments within a week of fertilization, when the fertilized egg has reached the blastocyst stage of development and contains up to 256 cells.

Although procedure is ethically debatable—particularly because the embryos are healthy—experts say that the research may help us understand how early development works and could increase the success rate of in vitro-fertilized embryos. Still, a local ethics board will need to approve the research before it begins—and the U.K. is sophisticated enough in its scientific infrastructure to make distinctions between research and reproductive consequences. These initial experiments could help scientists clarify the latter, and pave the way for deeper conversations about the clinical usage of CRISPR in the future.