Rivron’s lab was the first to create these embryo-like structures in 2018. His team has shown that mouse stem cells can self-assemble into blastocyst-like structures. A blastocyst forms 5-6 days after a sperm fertilizes an egg. They called the spheres of cells “blasts”.
Then, in 2021, several labs showed that stem cells could be used to create human blasts. And last year, researchers at the University of Cambridge and the California Institute of Technology reported that they had created a mouse structure that mimics an 8.5-day-old natural embryo, even complete with a beating heart and neural folds that underlie the brain.
The scientists behind these experiments claim that these cell spheres are just models and not actual embryos. ) prohibits the implantation of these structures into humans for the purpose of initiating pregnancy.
For now, scientists hope to use them to better understand early pregnancy. We hope to deepen our understanding of human embryonic development, including shedding light on some of the causes of this,” said Zhen Liu of the Chinese Academy of Sciences in Shanghai. , one of the study’s authors, in a press statement. (Liu’s team did not respond to an emailed request for comment by press time.)
Still, trying this in monkeys is the closest thing to what can happen in humans. says Hank Greeley, director of the Center for Law and Biological Sciences at Stanford University School of Medicine. “They say there is some evidence that baby monkeys may be born.”
Embryo research is particularly controversial in the United States, which has faced decades of religious opposition. Most states allow human embryo research, but national law prohibits the use of federal funds to create or destroy embryos.
Some countries, such as the UK, Canada, and South Korea, have legal restrictions on growing human embryos in the laboratory beyond 14 days post-fertilization. This is the time when the first signs of the central nervous system appear. (In other countries, the 14-day rule is just a guideline originally established by the ISSCR.) In 2021, the ISSCR will relax his 14-day rule and make it a case-by-case basis.
Embryo models offer researchers an alternative to relying on the real thing. But as they become more sophisticated, they pose their own concerns. “I think what we really want to know is can the embryo model give rise to an organism,” says Greeley. “If you can, treat it like an embryo. If you can’t, you don’t have to treat it like an embryo.”
To answer that question, Greeley advocates for scientists to conduct the kinds of experiments outlined in the new paper. I feel that it is unethical to do this to people because of the nature of my actions.
Rivron believes that scientists should move slowly in trying to establish blastoid pregnancy in animals because it is very likely that these structures will not develop correctly. But at the current pace of research in this area, he believes the first live mice born from blasts could become a reality within five years. “I think we need to take things step by step to get this right.”
In their press statement, the team behind the new paper acknowledged the research could be controversial. However, he emphasizes that there are still many differences between these embryo-like structures and natural blastocysts. They point out that discussion between the scientific community and the public is important for progress in this field.”
