Synthetic embryo with brain and beating heart created in ‘world first’

British scientists have succeeded in creating a 'synthetic' embryo which developed a brain and a beating heart.

In order to be successful, pregnancies need a 'dialogue' between an embryo and mother. In the first week after fertilisation, three types of stem cells develop; one of which becomes the tissues of the body while the others support the embryo’s development.

Each group has to send mechanical and chemical signals to each other to tell the embryo how to develop properly, but if this period goes wrong, the pregnancy will fail.

In their study, the researchers sparked development of their synthetic embryo by weaving together different cultured stem cells found in early mammalian development, representing each of the three types of tissue in the right proportions and environment to promote growth and communication.

Scientists induced the expression of a particular set of genes and established a unique environment to encourage them to communicate. After self-assembling into an embryo, the researchers found they signalled chemically, mechanistically and through touch.

There were no fertilised eggs and no sperm, but the model copied the stages of mouse embryo development that take place up to eight-and-a-half days after fertilisation.

Lead author Professor Magdalena Zernicka-Goetz explained: "Our mouse embryo model not only develops a brain, but also a beating heart, all the components that go on to make up the body."

"It's just unbelievable that we've got this far," she continued. "This has been the dream of our community for years, and major focus of our work for a decade and finally we’ve done it."

The embryo started to grow muscles, a gut and nervous system, which in turn offer insight into how tissues form and the causes of genetic diseases.

Prof Zernicka-Goetz said: "This period of human life is so mysterious, so to be able to see how it happens in a dish - to have access to these individual stem cells, to understand why so many pregnancies fail and how we might be able to prevent that from happening - is quite special.

"We looked at the dialogue that has to happen between the different types of stem cell at that time - we’ve shown how it occurs and how it can go wrong."

The professor also noted the model 'allows us to manipulate genes to understand their developmental roles in a model experimental system'.

As a result, the world-first creation could help solve the donor shortage crisis and prevent miscarriages. Following the success of the mouse embryo model, the researchers are now developing similar human models with the potential to generate specific organ types.

The professor explained: "There are so many people around the world who wait for years for organ transplants. What makes our work so exciting is that the knowledge coming out of it could be used to grow correct synthetic human organs to save lives that are currently lost.

"It should also be possible to affect and heal adult organs by using the knowledge we have on how they are made. This is an incredible step forward and took ten years of hard work of many of my team members - I never thought we'd get to this place.

"You never think your dreams will come true, but they have."

UK law currently permits human embryos to be studied in the laboratory only up to the 14th day of development.