Israeli scientists created a model human embryo from stem cells in the laboratory, without using sperm, egg cells or a uterus, providing a unique picture of the early stages of embryonic development. The model resembles an embryo at day 14, when it acquires internal structure but before laying the foundations for body organs, according to the team at Israel’s Weizmann Institute of Science.
The scientists’ work was publishe in the journal Nature on Wednesday, September 6, 2023, after the pre-print was publish in June, at the annual meeting of the International Society for Stem Cell Research (ISSCR) in Boston, USA.
The Israeli team stressed that they are still far from being able to create embryos from scratch.
“The question is, when is a model embryo considere an embryo? When that happens, we know the rules. Right now we are really far from that point,” said team leader Jacob Hanna.
However, they say this research could open the door to new ways to test the effects of drugs on pregnancy, better understand miscarriage and genetic diseases, and perhaps even to grow transplanted tissues and organs. “It’s not identical. There are indeed differences with human embryos, but still, this is the first time if you open an atlas or textbook you can say – yes, I really see the similarity,” said Hanna.
He said his team took stem cells derived from adult human skin cells
as well as other cells cultured in the laboratory, then returned the cells to their original state. They then manipulated it to form the basis of something that structurally resembled an embryo. These are not actual or synthetic embryos – terms criticized by ISSCR and other scientists – but rather models showing how embryos work. “At about 1 percent aggregate we can see that the cells start to differentiate properly. Migrate and sort themselves into the correct structure. And the furthest we can reach is day 14 in human embryonic development,” he said. Their next goal, Hanna said, is to advance to day 21 and also reach the 50% success rate threshold.
Magdalena Ernicka-Goetz, a professor of development and stem cells at the University of Cambridge, said the research joins six similar human embryo-like models published by teams around the world this year, including from her laboratory.
The study raises several ethical questions regarding the possibility of potential future manipulation in human embryo development, Hanna and other researchers said. However, he compared it to nuclear physics, arguing that you shouldn’t stop all research in that field because someone might choose to build a nuclear bomb. It is important to fully engage and inform the public, he said, without doing anything in secret.