Scientists were able to grow “synthetic embryos” without the need for sperm, eggs or uterus.
Studying these structures in mice could teach us how to grow organs for transplantation.
Making human babies in this way remains a distant prospect, full of ethical problems.
Scientists cultured “synthetic embryos” from mouse cells without using sperm, eggs or uterus.
The process, a world first, was featured in an issue of the peer-reviewed journal Cell on Aug.1.
The technology could be a starting point for growing organs from scratch, Jacob Hanna of Weizmann’s Department of Molecular Genetics, head of the research team, said in a statement.
Independent experts said much more research would be needed before even considering culturing a human embryo in this way.
However, this research makes this possibility a little more feasible, adding urgency to the ethical question, they said.
Cracking of the synthetic embryo code
“The embryo is the best organ production machine and the best 3D bioprinter – we tried to emulate what it does,” said Hanna.
Hanna and her team had already managed to grow mouse embryos outside the womb, in glass containers.
But those embryos were taken directly from real mice and were fertilized. In the latest study, embryos were grown from stem cells.
Cells learn what they should do by reading the chemical signals sent to them by the body.
Scientists can mimic those signals to turn stem cells into fake organs in a research dish, such as mini-brains used to test drugs.
Most of Hanna’s synthetic embryos died early in the process. But some managed to grow for 8.5 days, about half the gestational time of a mouse.
By that time, they were 95 percent similar to normal mouse embryos and had developed a placenta and the beginning of a spine and brain, digestive tract, beating heart, according to the study.
However, these are not “real” embryos, Hanna told the Guardian. For one, they weren’t able to grow to full term when they were inserted into a mouse’s uterus, she said.
Growing organs from synthetic embryos
Since these synthetic embryos are made up of stem cells, rather than via fertilization, it is easier to scale the process and create batches at once.
This could be valuable to science because it could make huge quantities of synthetic embryos available for research without relying on laboratory animals.
If these cells can be induced to create the start of organs, studying them could reveal the building blocks for creating organs from scratch for transplanting them into humans without the need for donors, Hanna said.
“Our next challenge is to understand how stem cells know what to do, how they self-assemble in organs and find their way to assigned points within an embryo,” said Hanna.
Still a long way from synthetic human embryos
James Briscoe, a group leader at the Francis Crick Institute in London not involved in the research, told the Guardian that the research raises ethical questions.
“Now is a good time to consider the best legal and ethical framework to regulate the research and use of synthetic human embryos and to update existing regulations,” he said.
We won’t see human embryos grown from stem cells anytime soon, Briscoe said. These synthetic mouse embryos were unable to develop into a live mouse. We also know a lot less about human embryos, which take much longer to complete and are much larger.
However, this innovation could set this field of research in motion, Paul Tesar, a developmental biologist at Case Western Reserve University School of Medicine who was not involved in the study, told STAT News.
“This is only one step, but a very important step for us to be able to study early development,” Tesar said.
“We are moving through the realm of the possibility of generating an embryo from scratch and potentially a living organism. It was a truly remarkable step for the field.”
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