A team of researchers at the Francis Crick Institute, London, edited the DNA of human embryos to find answers that could help explain the causes of miscarriages. They identified a gene called OCT4, deactivated it to see what happened and were surprised to discover that human development is not possible without it. IVF procedures could improve thanks to this new study published in Nature.
Similar experiments have been conducted in China and the United States to find out whether DNA editing can help prevent inherited diseases being passed down to future generations. However, it is the first time the technique is used to study the process of early human development to understand better why some women miscarry after going through IVF.
DNA editing and fertility
Study co-author Kay Elder said that IVF success rates could be improved by applying the technique, as reported by The Guardian. Elder, from the Bourn Hall fertility clinic in Cambridge, explained that following implantation a large number of embryos usually fail to continue developing. This research, he affirmed, will help identify the key factors required for human embryos to develop into healthy babies, which will ultimately give hope to infertile couples.
Invented in 2013, the genome editing procedure is known as CRISPR-Cas9 and has been increasingly used in biomedical research. By applying the technique, scientists can make exact edits to the genome to deactivate genes or try to correct genetic flaws.
Once an egg has been fertilized, it turns into a blastocyst during the first seven days. A blastocyst is shaped like a ball of cells. An embryo is only able to implant in the womb after successfully reaching the blastocyst stage, which has three cell types designed to develop into the embryo, the placenta, and the yolk sac.
The researchers used 41 human embryos donated by couples who did not need them anymore after IVF treatment and applied the technique to deactivate OCT4, which they believed was an essential gene in the earliest stages of human development. By using a microscope, they were able to observe that the modified embryos divided and normally expanded at the beginning but then experienced cycles of expansion and collapse without going on to the next stage.
The study showed evidence that OCT4 is essential in the process in which the embryo turns into a blastocyst. A lower activity of this gene could explain why miscarriage occurs after embryos fail to implant normally. The researchers believe an adequate treatment could be possible without gene editing. Instead, they could change the way embryos are cultured for the IVF procedure to induce more activity from OCT4.
This new study provides sufficient evidence to say that the gene apparently acts differently in early human embryos than in mice. Dusko Ilic, a reader in stem cell science at King’s College London, told The Guardian that this research contradicts the thought that experiments in mammalian species can always be extrapolated to humans. As fertility treatments tend to rely on mouse studies, the British scientists might have found the reason why the success rate is so low.
Source: The Guardian