The team from London's Francis Crick Institute was the first to probe gene function in spare embryos from IVF clinics using the powerful technique.
Understanding the biology behind the early stages could help in the discovery of ways to improve the success of in-vitro fertilization, offer some explanation into why some women experience miscarriage and offer general knowledge on how humans develop. The findings show that the gene controls the fate of several cell lineages and has a slightly different role in humans than in mice.
In the long run, however, its greatest benefit is likely to be a way of sending adult cells back to an early stage of development that allows them to fix damage to any part of the body. The UK Human Fertilisation and Embryology Authority granted permission to do the study - the first time a national regulator has approved research involving gene editing in human embryos (previous studies in other countries were endorsed by local review boards).
Lead author Kathy Niakan (Francis Crick Institute, London) says she hopes the technique can be used by others to identify a whole host of genetic factors that affect pregnancy, but are now poorly understood: "One way to find out what a gene does in the developing embryo is to see what happens when it isn't working".
"It may take many years to achieve such an understanding, our study is just the first step".
Using CRISPR-Cas9, the team were able to change the DNA of 41 human embryos.
Invented in 2013, the genome editing procedure is known as CRISPR-Cas9 and has been increasingly used in biomedical research.
After seven days, embryo development was stopped and the specimens were analyzed.
The embryos used for the study were donated from couples who had a surplus after IVF treatment.
Lanner, whose lab is conducting studies with CRISPR of other genes that are crucial for embryo development, points to the importance of painstakingly optimizing the experimental conditions in mouse embryos before moving the studies to human embryos, as Niakan's team had done.
"In humans, (OCT4) not only maintains the embryo, but other tissues are affected and the blastocyst does not form", said Ludovic Vallier, a stem cell biologist at the Wellcome Trust Sanger Institute who co-authored the research.
Director of the Crick Institute, Sir Paul Nurse, denied that this was the case. Many describe it as game-changing.
In August, the United States had its own first successful CRISPR breakthrough, discovering it was possible to remove genes for diseases - in that study, genetic heart disease - from embryos.
Many experts believe the form of research is pivotal to gaining a better understanding of how humans develop. Manipulating the DNA in the embryos can also give scientific insights into how a single cell can divide and become a human in the future. "Many embryos arrest in culture, or fail to continue developing after implantation; this research will significantly help treatment for infertile couples, by helping us to identify the factors that are essential for ensuring that human embryos can develop into healthy babies".
Rob Buckle, Chief Science Officer at Britain's Medical Research Council, praised the "groundbreaking research".