A stem cell is a specific cell in an animal that has the potential to become many types of cells. Both mouse and human stem cells do this, although in different ways.
The researchers hope their embryonic model will help future mothers deepen their understanding of why some pregnancies fail early and others succeed. In addition, “embryos” could help reduce the use of animals in research and could one day supplement the limited supply of transplantable human organs with synthetic organs.
Professor Jacob Hanna, from the Department of Molecular Genetics at the Weizmann Institute of Science in Israel, said: “We may one day be able to create a model similar to a synthetic embryo and then isolate the cells we need, rather than for every cell type — Cells such as the kidney or liver develop different protocols for growth. We won’t need to dictate to emerging organs how they have to develop. The embryo itself does this best.”
Earlier this month, a team led by Hannacellpublished a study on its synthetic mouse embryos in the journal. Last week, scientists at the University of Cambridgenaturemagazine detailed their own similar but independent work, employing techniques shared by Hanna’s group. Both teams spent more than 10 years perfecting their embryos.
Magdalena Zernicka-Goetz, Professor of Mammalian Development and Stem Cell Biology at the University of Cambridge’s Department of Physiology, Developmental and Neuroscience, said: “This has been a dream of our community for many years and a major focus of our work for a decade, and we have finally achieved it.”
In research in the journal Nature, the Cambridge University team explains how it allows three types of stem cells in early mammal development to “communicate” with each other. This “communication” is key because the cells’ interactive signals guide the development of the embryo. The mouse stem cells eventually assembled themselves into an embryo, which developed over 8.5 days until it had a structure that resembled a beating heart, and a brain with well-defined forebrain and midbrain regions.
Many pregnancies fail around the time this cellular organization occurs — and before most people even realize they’re pregnant.
“This period is the foundation of everything else after pregnancy. If it goes wrong, the pregnancy fails. Studying in detail how stem cells are assembled could ultimately help scientists like Zernicka-Goetz determine the exact time when those ill-fated problems in pregnancy. “
Kirstin Matthews, a science and technology researcher at Rice University’s Baker Institute for Public Policy, called the study “intriguing.”
“It provides additional knowledge about how cells organize and specialize early in development,” said Matthews, who was not involved in the two teams’ research. “This knowledge was previously limited because it required implantation in the animal’s uterus, which is not easily observable.”
Of course, news of synthetic embryos might give futuristic-minded people the illusion of growing outside of a living womb. But developing embryos with synthetic organs from human stem cells is still a long way off due to technical challenges, not to mention ethical complexities such as when exactly these structures can be considered embryos. Matthews warned that their progress deserves careful discussion and serious consideration.
For now, though, Hanna doesn’t see any major concerns. “Synthetic embryos are so different from natural embryos that they won’t be viable and can’t be transplanted back into the uterus. We’re just talking about a very complex differentiation protocol that produces real cell types,” said Hanna, who is an associate of a company Founder, the company applies stem cell technology to health problems such as infertility and genetic diseases.