Researchers in the UK have used CRISPR gene editing on an embryo for the first time.

The CRISPR–Cas9 genome-editing technique has been used to study the role of the OCT4 gene in early human embryo development.

The findings provide new insights into the molecular mechanisms that control embryogenesis and represent proof of principle that CRISPR–Cas9 genome editing can be used to evaluate gene function in early human development.

During early human development, the zygote (fertilized egg) differentiates into a blastocyst comprising 200-300 cells that have distinct roles: some, known as pluripotent epiblast cells, go on to form the fetus, while others, extra-embryonic cells, contribute to the placenta and yolk sac.

However, the mechanisms underlying these early ‘cell fate’ decisions have remained unclear. 

OCT4 is a gene that is thought to be required for pluripotency and reprogramming in human cells, but whose function in early human embryos is poorly understood.

Researchers used an optimized CRISPR-Cas9 genome editing approach to target OCT4 in human zygotes donated as surplus to infertility treatment.

The authors of a new report show that OCT4 is required early in human development, and that when its expression is suppressed blastocyst development is compromised.

They also uncovered roles for OCT4 in regulating the expression of genes involved in the extra-embryonic cells that later form the placenta, and of pluripotent genes that define the epiblast.

The authors conclude that their study provides a framework for future investigations that could further enhance our understanding of human embryo development, which could eventually lead to improvements in the development and therapeutic use of stem cells and in IVF treatment.

Their latest papers are accessible here and here.