Genome editing sheds light on human embryo development

Researchers have used genome editing technology to reveal the role of a key gene in human embryos in the first few days of development.

Human embryo at eight-cell stage
Coloured scanning electron micrograph of an embryo at the eight-cell stage, three days after fertilisation.
Credit: Science Photo Library

It’s the first time that editing of the genome – the complete set of genes in a cell or organism – has been used to study gene function in human embryos.

The research could help scientists to better understand the biology of our early development.

Dr Kathy Niakan from the Francis Crick Institute, who led the research, said: "If we knew the key genes that embryos need to develop successfully, we could improve IVF treatments and understand some causes of pregnancy failure. It may take many years to achieve such an understanding, our study is just the first step."

Role of key gene revealed

The team spent over a year optimising their techniques using mouse embryos and human embryonic stem cells before starting work on human embryos.

They then used CRISPR-Cas9 genome editing techniques in the embryos to stop a key gene from producing a protein called OCT4. This protein normally becomes active in the first few days of human embryo development. After seven days, embryo development was stopped and the embryos were analysed.

After the egg is fertilised, it divides for about seven days until it forms a ball of around 200 cells called the ‘blastocyst’. The study found that human embryos need OCT4 to correctly form a blastocyst.

A transformative tool for research

Dr Andrew Chisholm, Head of Cellular and Developmental Science at Wellcome, said: "This landmark study confirms CRISPR’s status as a transformative tool for research. Although studying human embryos is more challenging than similar experiments in mice, this work underscores why such studies are key to understanding our own biology."

The research was published in Nature and led by scientists at the Francis Crick Institute. It was chiefly funded by the UK Medical Research Council, Wellcome and Cancer Research UK.

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