By Michael Le Page A team of biologists in the UK have been given the go-ahead from the UK Human Fertilisation and Embryology Authority to perform gene-editing in human embryos. The project, led by Kathy Niakan of the Francis Crick Institute in London, could be the first outside of China to try the technique in humans. New Scientist takes a look at their plans and how the work could improve fertility treatments. Have human embryos been gene-edited before? Yes. At least four teams in China have done this using the CRISPR method of gene-editing. As far as we know, the point of these experiments was simply to see how well CRISPR works in human embryos. What is Niakan’s team proposing, and what would this tell us? They want to use CRISPR to unpick which genes control early development in humans. Ultimately, this research could reduce the number of miscarriages and improve fertility treatments. Only half of all IVF embryos develop sufficiently to be implanted in women, and less than half of those are carried to term. Why these rates are so low is something that the proposed research could help us understand. What will the study involve? During the first week of embryonic development, cells start to take on different roles. Some go on to form the placenta and yolk sac, others to form the child itself. Biologists think they have identified some of the genes that determine which cells take on which role, but the only way to be sure is to disable those genes and see what happens. Niakan plans to use the CRISPR technique to disable genes in single-cell embryos, just a day old. After about seven days the team will kill the embryos and analyse their structure to see what, if any, disruption there has been to the embryos’ ability to organise. They want to try this with three or four genes, first and foremost one called OCT4. How will this help improve fertility treatments and reduce miscarriages? There are at least three potential ways. First, identifying the genes crucial in early development could lead to better ways of selecting healthy embryos for IVF. Second, it could help improve the “soup” used to grow embryos for their first few days. At present, the growth media used by clinics are variants on recipes originally developed for mice, and some of these seem to affect male and female embryos differently. Third, it could help identify mutations that affect early development and lead to miscarriages. One day some countries may allow would-be parents to correct these defects – so-called germline gene therapy. Can’t we do this research in animal embryos instead? Similar work is already under way in animals. But although animal studies have told us a lot about how mammals generally develop, there are significant differences between lab mice and people. There are genes active in human embryos that are inactive in mouse embryos and vice versa, for instance. Where will the embryos come from? The team plan to use spare frozen IVF embryos, donated by the parents. About 20 to 30 embryos will be required per gene studied, Niakan estimates, so around 120 may be needed in total. When could we see the first use of gene editing on human embryos happening in the UK? Probably later this year. As well as approval from the HFEA, Niakan’s team also needs to secure the approval of a separate ethics committee. Then her team will start collecting frozen donor embryos, which could take several months. Does this research take us closer to germline gene therapy? Not directly, although if Niakan’s team find ways to improve the efficiency of gene-editing that are specific to human embryos, it could eventually be of use to those who want to create gene-edited babies. Discover more on our special page on CRISPR gene editing (Image credit: ZEPHYR/SPL)
UK-based scientists from London's Francis Crick Institute have requested permission from the Human Fertilisation and Embryology Authority (HFEA) to edit the genes of today embryos; a panel is due to convene day-old to debate the merits of the application. Lead researcher Kathy Niakan is seeking endorsement to edit embryos' genes in order to develop better treatments for infertility and miscarriages.