Synthetic embryos with brain created
Lab-grown stem cell embryos with a complete brain have been created for the first time by Cambridge scientists in a “holy grail” breakthrough.
Mouse stem cells were used to form the man-made embryos, bypassing the need for egg fertilisation by a sperm.
Earlier this month, an Israeli team reported producing similar synthetic embryos but the work from Professor Magdalena Zernicka-Goetz’s Cambridge team is the first to grow a whole brain, in addition to other organs such as a heart.
While the previous research made embryos with a partial brain, the British scientists were able to push development further, achieving full formation for the first time.
“The important step forward . . . was the development of the anterior region [of the brain] that’s so clearly demonstrated in this publication,” said Professor David Glover, study co-author from the California Institute of Technology.
“This is really the first demonstration of the development of the forebrain in any of these models of embryonic development, and that has been a holy grail for the field.”
Zernicka-Goetz added: “This has been the dream of our community for years, and a major focus of our work for a decade and finally we’ve done it.”
The embryonic forebrain develops into most of the human brain, including the cerebrum — responsible for all “higher functions” including speech, problem solving, and learning.
Being able to study the progress of this structure is therefore a vital development, scientists say, in order to understand more about congenital brain defects.
“This opens new possibilities to study the mechanisms of neurodevelopment,” said Zernicka-Goetz.
The research also raises hopes for the prevention of miscarriages because the majority of pregnancies fail in the earliest stages of development.
Zernicka-Goetz said the synthetic embryos will help them “understand why so many pregnancies fail and how we might be able to prevent that from happening”.
A mouse pregnancy lasts 20 days and the embryos in the study were grown for 8.5 days, allowing researchers to mimic the first, and most dangerous, period of pregnancy.
This early period sees three types of stem cells — master cells able to morph into almost any other cell type in the body — form a nascent embryo.
One type becomes the embryo and the other two develop into a placenta and yolk sac to support its growth.
The three types of stem cells must communicate with each other via chemical and physical signals and issues in this process can cause a miscarriage.
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.”
The researchers are focusing their pioneering work on mice but hope to use human stem cells in the future.
Zernicka-Goetz added: “The knowledge coming out of it could be used to grow synthetic human organs to save lives.
“This is an incredible step forward and took 10 years of hard work of many of my team — I never thought we’d get to this place. You never think your dreams will come true, but they have.”