According to the scientists of the Weizmann Institute in Israel, stem cells from mice can be transformed into primitive embryo-like formations with their own intestinal tract, brain and functional heart.
They called them "synthetic embryos" because they were created without fertilized eggs. They should, in the short term, help us better understand how organs and tissues are formed during the development of natural embryos. And not only.
The study authors are optimistic that the procedure could reduce the use of animal testing and ultimately lead to new sources of cells and tissues for human transplants. The skin cells of a leukemia patient, for example, could be converted into bone marrow stem cells to alleviate her condition.
Synthetic embryos, natural benefits
“Surprisingly, we show that embryonic stem cells generate whole synthetic embryos. They include the placenta and the yolk sac that surround the embryo, ”said prof. Jacob Hanna, at the head of the research team. "We are really excited about this work and its implications." The research was published in the scientific journal Cell (I link it to you here).
Last year, the same team built a kind of mechanical uterus that allowed natural mouse embryos to grow outside the uterus for several days.
The phases of the research
In this latest study, the same "mechanical uterus" was used to feed mouse stem cells for more than a week, nearly half the gestation time of a mouse. Some of the cells were pretreated with chemicals, which activated genetic programs to develop in the placenta or yolk sac, while others developed without intervention on organs and other tissues.
Results? Most stem cells have failed to form embryo-like structures, but approx 0,5% it combined and grew distinct tissues and organs. Synthetic embryos are 95% identical in structure and genetic profile to natural mouse embryos, and have functional organs.
Synthetic embryos: possible developments
Prof. Hanna is keen to specify that synthetic embryos are not "real" embryos and do not have the potential to develop into live animals, or at least they did not have when they were transplanted into the uterus of female mice. On the basis of this research he founded a company called Renewal Bio, which aims to cultivate synthetic human embryos to provide tissues and cells for medical conditions. It can be done?
“In Israel and many other countries, such as the US and UK, it is legal. We have ethical approval to do this with human-induced pluripotent stem cells. This will provide an ethical and technical alternative to using embryos, ”said Hanna.
Ethical doubts are inevitable
Doctor James Briscoe of the Francis Crick Institute in London (which was not involved in the research) finds it important to discuss how best to regulate this type of research before synthetic human embryos are developed. I agree with him.
Human synthetic embryos are not an immediate prospect. Further developments will be needed, it is not as simple as for the mouse ones. For this reason, now is the right time to define a legal and ethical framework: this type of research must be regulated, and the current regulations must be updated.
"There will always be a gray area," predicts the scientist. "However, as scientists and as a society, we must come together to determine where the limit is and what is ethically acceptable."
And it is no small thing.
