In DepthDevelopment

Embryo edit makes human ‘knockout’

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Science  22 Sep 2017:
Vol. 357, Issue 6357, pp. 1225
DOI: 10.1126/science.357.6357.1225-b

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For the first time, scientists have used gene-editing techniques on human embryos to probe how they develop. The study is an important proof of principle; previous human embryo–editing research has focused instead on correcting faulty genes. The new experiments are also a first test of the United Kingdom's carefully crafted embryo-editing research regulations, which require that researchers undergo a review by a government authority and receive a license before moving forward. Kathy Niakan, a developmental biologist at the Francis Crick Institute in London, applied in 2015 to use the CRISPR editing technique on human embryos to learn more about the genes active in early development. The researchers planned to focus first on OCT4, known as a marker for pluripotent stem cells—cells that can become all tissues in the body. Niakan's group used CRISPR to "knock out," or deactivate, the gene that codes for OCT4 in 37 single-cell human embryos left over after in vitro fertilization treatments and donated by couples. In the human embryo knockouts, placental cells failed to form, indicating that OCT4 plays an earlier role in humans than it does in mouse embryos.