Vital role played by fertility 'master gene' revealed

This latest experiment, led by researchers at London's Francis Crick Institute, is the first in which scientists used genome-editing technology to investigate the function of a particular gene in human embryos, according to an institute release.

The team focused on OCT4, a protein that normally gets activated within the first few days of human embryo development.

"Other research methods, including studies in mice, suggested a later and more focused role for OCT4, so our results highlight the need for human embryo research".

Once an egg has been fertilized, it turns into a blastocyst during the first seven days. [This study shows that] OCT4 plays somewhat different roles in human than in mouse preimplantation embryos.

The scientists discovered a gene called Oct4 is vital to the successful development of an embryo after fertilisation, and without it, a viable pregnancy is highly unlikely.

"We were surprised to see just how crucial this gene is for human embryo development, but we need to continue our work to confirm its role", said Norah Fogarty of the Francis Crick Institute, first author of the study, which was published Wednesday in the journal Nature. CRISPR-CAS9 is a new and much-heralded technique, using a chemical process borrowed from bacteria, that allows scientists to remove specific lengths of DNA from cells. They performed this technique on 41 human embryos, then "stopped embryo development" at the seventh day after conception to analyze the results of their actions. The majority were donated by couples who had completed their family, and wanted their surplus embryos to be used for research.

The Francis Crick Institute team was only given the go-ahead to conduct the research by the Human Fertilisation and Embryology Authority fertility regulator a year ago.

"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.

Sir Paul Nurse, Director of the Francis Crick Institute, says: "This is exciting and important research".

In 2015 Chinese scientists led by Dr Junjiu Huang shocked the world by announcing they had carried out the first attempt to tackle an inherited disease by gene-editing human embryos.

"There's nothing irresponsible about the research in this case", says stem cell researcher Paul Knoepfler of the University of California, Davis, School of Medicine. What the researchers didn't expect is that OCT4 also affects the development of the placenta precursor cells on the outside of the blastocyst. Instead, they could change the way embryos are cultured for the IVF procedure to induce more activity from OCT4. Researchers have relied on mouse models to understand early mammalian development, she adds, but to understand human development and how it can go wrong, the real thing may be best.

Pioneering British scientists have identified a key gene that may help to explain why so many IVF pregnancies fail. "Thus, this research will open new fields of opportunity for basic and translational applications".

Rob Buckle, Chief Science Officer at Britain's Medical Research Council, praised the "groundbreaking research".

  • Delores Daniels