Scientists Turned Monkey Stem Cells Into ‘Synthetic Embryos’

Rivron’s laboratory was the first to create these embryo-like structures in 2018. His team showed that mouse stem cells can self-organize into structures that resemble a blastocyst, which forms five or six days after sperm fertilizes an egg. They dubbed the balls of cells “blastoids.” 

Then in 2021, several labs showed they could create human blastoids using stem cells. And last year, researchers at the University of Cambridge and the California Institute of Technology reported that they created mouse structures mimicking natural embryos at 8.5 days of development, which even had beating hearts and neural folds, the foundations of the brain.

Scientists behind these experiments insist that these balls of cells are just models, not actual embryos. The International Society for Stem Cell Research, or ISSCR, a scientific group that sets guidelines for stem cell research, prohibits these structures from being transferred into humans for the purpose of trying to start pregnancies. 

For now, scientists want to use them to better understand early pregnancy. “Because monkeys…