- Philippa Roxby
- BBC health correspondent
image source,Amadei and Handford
The synthetic embryos showed comparable brain and heart formation, the researchers said.
Scientists at the University of Cambridge have created a batch of synthetic mouse embryos in the lab, a process that does not involve eggs or sperm. Synthetic embryos have brains and beating hearts.
The mouse embryos, grown from stem cells, survived for only eight days, but the team said this could help improve understanding of the earliest stages of organ formation, and why some embryos abort.
Other scientists have reservations about the approach. They point out that while the technology appears mature, there are still many hurdles to overcome.
The Cambridge team has been studying the early stages of pregnancy for the past 10 years, but much of the activity is hidden in the womb of a pregnant woman and cannot be seen.
But by mimicking natural processes in the lab, they found a way to get three types of mouse stem cells to interact to grow embryo-like tissue.
However, due to developmental defects, these embryos only survived for eight days, but they finally caught up with the stage when the brain began to develop.
Prof Magdalena Zernicka-Goetz is Professor of Mammalian Development and Stem Cell Biology at Cambridge and Professor of Biology at Caltech. She said the research advance is a “dream come true” that promises to offer a glimpse into how organs are formed.
image source,Amadei and Handford
Comparing natural embryos with synthetic embryos, after eight days of formation, the two appear very similar.
She said: “This stage of human life is full of mysteries, being able to see how this happens on a petri dish – getting access to individual stem cells, understanding why so many pregnancies fail, and how we might be able to avoid it ( miscarriage) happens ā itās a very special experience.ā
The advance also means less reliance on live animals for research and could be a useful way to test new drugs.
Peers take a wait-and-see attitude
However, says Prof Alfonso Martinez Arias of Universitat Pompeu Fabra, Barcelona, āāSpain: “This is an advance, but only at a very preliminary stage of development. While superficially resembling an embryo, this is a flawed rare event that cannot be ignored.”
The researchers now plan to try to keep the synthetic embryos alive for an extra day or two. This is a very difficult thing to do without a synthetic placenta.
Their ultimate goal is to grow similar embryos from human stem cells, but this is not only a long way to go, but also has complex ethical issues.
Current UK law allows human embryos up to 14 days old to be studied in the laboratory, while synthetic embryos have no rules.
That should change, says Prof Robin Lovell-Badge of the Francis Crick Institute in the UK.
“It’s natural to consider whether and how these integrated stem cell-based embryo models should be regulated, based on their similarity to real embryos,” he said.
He also added that these embryo-like models cannot be easily “taken as real, even as they become more and more real.”
“If these (synthetic embryos) are derived from human stem cells, and it’s accepted that these (embryos) can never be transferred into the uterus, then we’ll never know if the two are equal.”