In a breakthrough that redefines how life can be created, embryologists working at the University of Cambridge in the UK have grown realistic-looking mouse embryos using only stem cells. No egg. No sperm. Just cells plucked from another embryo.
Artificial embryos built from scratch using stem cells have been created by scientists.
Researchers bypassed the act of fertilization by growing the self-assembling structures in the laboratory. Although the cells used came from mice, the experiment has opened up a new frontier in embryo research with major ethical implications.
Creating embryos in the lab is expected to help scientists unlock the mysteries of early human development. However, one expert said any artificial embryos made from human stem cells would have to be the subject of an “ethical discussion”. Attempting to create a baby from such a technique would be outlawed in the UK.
The researchers placed the cells carefully in a three-dimensional scaffold and watched, fascinated, as they started communicating and lining up into the distinctive bullet shape of a mouse embryo several days old.
The Cambridge University team led by Professor Magdalena Moniker Goethe had previously used two types of stem cell and a “jelly” scaffold to produce a much simpler 3 D structure resembling a mouse embryo. Now the scientists have taken a big step forward by bringing together all three stem cell types that form the basis of a fully formed embryo.
For the first time, this happened that scientists try to create artificial embryo-like structures they created were capable of “strangulation” the critical point at which an embryo divides into three distinct layers that determine the future fate of its cells. Only after strangulation can an embryo go on to develop into a viable fetus with all its tissues and organs in the right place.
Prof Moniker Goethe said: “Proper strangulation in normal development is only possible if you have all three types of stem cell. In order to reconstruct this complex dance, we had to add the missing third stem cell.
“By replacing the jelly that we used in earlier experiments with this third type of stem cell, we were able to generate structures whose development was astonishingly successful.”
The artificial embryos were observed undergoing strangulation and organizing themselves into the three fundamental body layers, known as the mender, mesosphere and echinoderm. Cells from the mender the innermost layer go on to form the digestive system, liver, pancreas and inner part of the lungs.
The mesosphere, or middle layer, produces the circulatory system, lung surfaces, skeleton and muscular system. The outer echinoderm contains the blueprint for the hair, nails, skin and nervous system. The research is reported in the journal Nature Cell Biology.
Moniker Goethe says her “synthetic” embryos probably couldn’t have grown into mice. Nonetheless, they’re a hint that soon we could have mammals born without an egg at all.
That isn’t Moniker Goethe’s goal. She wants to study how the cells of an early embryo begin taking on their specialized roles. The next step, she says, is to make an artificial embryo out of human stem cells, work that’s being pursued at the University of Michigan and Rockefeller University. Synthetic human embryos would be a boon to scientists, letting them tease apart events early in development. And since such embryos start with easily manipulated stem cells, labs will be able to employ a full range of tools, such as gene editing, to investigate them as they grow.
Under British law, only donated human embryos less than 14 days old can be studied in the laboratory, after which they have to be destroyed. Artificial embryos could help scientists study events in human pregnancies beyond day 14 without breaking this rule.
Doctor Christopher Cliche, from the Frances Crick Institute in London, said: “It is not too far-fetched to think the technique could one day be applied to studying early human embryos.
“These self-assembled human embryos would be an invaluable tool to understand early human development as well as understanding when things go wrong, but we are not there yet.
“Furthermore, ethical discussion would need to assess the status of these self-organized embryos if the method described in this paper did work with human stem cells.”
Artificial embryos, however, pose ethical questions. What if they turn out to be indistinguishable from real embryos? How long can they be grown in the lab before they feel pain? We need to address those questions before the science races ahead much further, bioethics say. Antonio Regal ado.
It’s a very revolutionary step for the human generation that scientists are now trying to produce artificial fetus for human growth, which looks like an impossible thing. But in the USA this work is still in process.