World-first “synthetic embryos” made from mouse stem cells
Scientists from the Weizmann Institute of Science (Weizmann Institute) in Israel have created “synthetic embryos” without the need for sperm, eggs, and fertilisation. The remarkable discovery instead makes use of stem cells from mice, which self-assembled into early embryo-like structures complete with a beating heart, an intestinal tract, and the beginnings of a brain.
The synthetic embryos are expected to drive deeper understanding of how organs and tissues form during natural embryonic development and reduce animal experimentation. The structures formed could also potentially become new sources of cells and tissues for human transplantation.
According to team lead Professor Jacob Hanna at the Department of Molecular Genetics, Weizmann Institute, some of the mouse stem cells had been pre-treated with chemicals, which switched on genetic programmes to develop into placenta or yolk sac, while other cells developed without intervention – Professor Hanna said that 0.5% of cells experimented on combined into little balls that grew distinct tissues and organs.
In addition, when compared with natural mouse embryos, the synthetic embryos were 95% the same in terms of their internal structure and the genetic profiles of the cells, while the structures developed into functioning organs.
However, the synthetic embryos were not “real” and did not develop into live animals, or at least they hadn’t when they had been transplanted into the wombs of female mice, the scientists noted.
The same team of scientists had last year built a mechanical womb that enabled natural mouse embryos to grow outside the uterus for several days. That device was used this time to nurture mouse stem cells for more than a week, nearly half the gestation time for a mouse.
Professor Hanna expects to grow human synthetic embryos to provide tissues and cells for medical conditions in the near future.
“In Israel and many other countries, such as the US and the UK, it is legal and we have ethical approval to do this with human-induced pluripotent stem cells. This is providing an ethical and technical alternative to the use of embryos,” Professor Hanna said.
