Think of the beginning of the embryo, probably the egg, sperm and uterus. Think again now. Using mouse stem cells grown in petri dishes, scientists in the UK and Israel have succeeded in creating synthetic models of embryos that, like biological models, develop a brain, beating heart and gut.
Stem cells are the raw material of the human body and have the potential to become a variety of cells. Both mouse and human stem cells can do this, although they do it differently.
Natural embryos on synthetic embryos show similar brain and heart formation.
Amadei and Handford/Cambridge University
The researchers hope their embryonic model will help future mothers improve their understanding of why some pregnancies fail early and others fail. In addition, “embryo-like” could help reduce the use of animals in research and could one day supplement the limited supply of transplantable human organs with synthetic organs.
“Instead of developing a different protocol for each cell type, such as those of the kidney or liver, we may one day be able to create a synthetic embryo-like model and then isolate the cells we need,” Professor Jacob Hanna from the Department of Molecular Genetics at the Weizmann Institute of Science in Israel said. “We don’t need to dictate how emerging organs must develop. The embryo itself does this best.”
Synthetic embryos have a moment.
A team led by Hanna published research on their synthetic mouse embryos earlier this month in the journal Cell. Last week, scientists at the University of Cambridge detailed their own similar but independent work in the journal Nature, unearthing techniques shared by Hannah’s group. Both teams have spent more than 10 years perfecting their embryos.
“This has been a dream of our community for many years and the main focus of our work for a decade, and finally we have done it,” said Magdalena Zernicka-Goetz, a professor at the university. Mammalian Development and Stem Cell Biology in the Department of Physiology, Development and Neuroscience at the University of Cambridge, where he led the team’s research.
In the Nature study, the Cambridge team explains how it allows three types of stem cells found in early mammalian development to “talk” to each other.
This communication is key because the cells’ interactive signals guide embryonic development. The mouse stem cells eventually assembled themselves into an embryo that developed within 8.5 days until it had a beating heart-like structure and a brain with well-defined forebrain and midbrain regions.
Many pregnancies fail when this cellular organization occurs – before most people even realize they are pregnant.
“This period is the foundation of everything else after the pregnancy. If something goes wrong, the pregnancy fails,” says Zenica-Getz. A detailed study of how stem cells are assembled could eventually help scientists like Zernicka-Goetz determine what went wrong in those ill-fated pregnancies.
Will human embryos be next?
Kirstin Matthews, a technology fellow at Rice University’s Baker Institute for Public Policy, called the study “fascinating.”
“It provides additional knowledge about how cells organize and specialize early in development,” said Matthews, who was not involved in either team’s research. “This knowledge was previously limited because it required implantation in the uterus of an animal, which was not easy to observe.”
Of course, talk of synthetic embryos may confuse the futuristic-minded Think of someone growing outside a living womb. But developing synthetic organ-germination embryos from human stem cells is a long way off due to technical challenges, not to mention ethically complex issues such as when exactly these structures can be considered embryos. Matthews cautioned that their progress requires careful discussion and serious accountability.
Still, Hannah doesn’t see any major issues, at least for now.
“Synthetic embryos are very different from natural embryos and will not be viable and cannot be transplanted back into the uterus,” said Hannah, co-founder of a company that applies stem cell technology to Health problems such as infertility and genetic diseases. “We’re just talking about a very complex differentiation protocol that yields real cell types.”
