The world’s first “synthetic embryos” have been successfully created by scientists at the Weizmann Institute in Israel, bypassing the need for sperm, eggs and fertilisation.
The scientists found that stem cells from mice could be made to self-assemble into early embryo-like structures with an intestinal tract, the beginnings of a brain and a beating heart.
This marks the first time researchers have grown fully synthetic mouse embryos outside the womb.
The Guardian reports: Known as synthetic embryos because they are created without fertilised eggs, the living structures are expected, in the near term, to drive deeper understanding of how organs and tissues form during the development of natural embryos.
But researchers believe the work could also reduce animal experimentation and ultimately pave the way for new sources of cells and tissues for human transplantation. For example, skin cells from a leukaemia patient could potentially be transformed into bone marrow stem cells to treat their condition.
“Remarkably, we show that embryonic stem cells generate whole synthetic embryos, meaning this includes the placenta and yolk sac surrounding the embryo,” said Prof Jacob Hanna, who led the effort. “We are truly excited about this work and its implications.” The work is published in Cell.
Last year, the same team described how they had built a mechanical womb that enabled natural mouse embryos to grow outside the uterus for several days. In the latest work, the same device was used to nurture mouse stem cells for more than a week, nearly half the gestation time for a mouse.
While most of the stem cells failed to form embryo-like structures, about 0.5% combined into little balls that grew distinct tissues and organs. 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. As far as the scientists could tell, the organs that formed were functional.
Hanna said synthetic embryos were not “real” embryos and did not have the potential to develop into live animals, or at least they hadn’t when they had been transplanted into the wombs of female mice. He has founded a company called Renewal Bio that aims to grow human synthetic embryos to provide tissues and cells for medical conditions.
“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,” Hanna said.