The research, announced by Professor Magdalena Żernicka-Goetz of the University of Cambridge and the California Institute of Technology, has not yet been published in a peer-reviewed journal. But Żernicka-Goetz told the meeting these human-like embryos had been made by reprogramming human embryonic stem cells.
What Did the Researchers Do?
Each of these synthetic human embryos is created from a single stem cell. Żernicka-Goetz described how her team grew the synthetic embryos to a stage of development called “gastrulation,” which is a stage just beyond the 14-day developmental mark for a human embryo.The current legal limit to how long a human embryo can be permitted to develop in a lab is 14 days.
This is approximately the length of time from fertilization of the egg to implantation in the uterine wall if conception has taken place within a human womb.
So, synthetic embryos have—for the first time—been allowed to develop past this point.
Initially, the 14-day rule was both a moral and a practical limit—scientists didn’t have the technology to keep embryos alive longer than this.
It’s further remarkable they seem to behave, in terms of development, like a human embryo would in some ways.
Żernicka-Goetz reported the human-like embryos began to develop placenta and yolk sacs, but not a beating heart or the beginning of a brain.
Moral Quandaries
However, just as there are real possibilities for gaining knowledge from synthetic human-like embryos, there are also real moral quandaries.One of these quandaries arises around whether their creation really gets us away from the use of human embryos.
Robin Lovell-Badge, the head of stem cell biology and developmental genetics at the Francis Crick Institute in London, UK, reportedly said that if these human-like embryos can really model human development in the early stages of pregnancy, then we will not have to use human embryos for research.
At the moment, it is unclear if this is the case for two reasons.
First, the embryos were created from human embryonic stem cells, so it seems they do still need human embryos for their creation. Perhaps more light will be shed on this when Żernicka-Goetz’s research is published.
Second, there are questions about the extent to which these human-like embryos really can model human development.
There could be significant limits to the usefulness of these synthetic embryos for learning about human developmental issues if human-like synthetic embryos aren’t capable of developing into full human babies and do not form important body structures like a beating heart and a brain.
One of the reasons researchers want to use these embryos is for research into miscarriage and developmental anomalies. This is very important, but will these synthetic embryos be “close enough” to real human embryos to reveal useful answers?
Is It Morally Permissible?
This leaves us with the important moral question about whether it is permissible to use human embryos for research.Further, if the human-like synthetic embryos are capable of developing into full living beings, then we must consider whether it is morally permissible to create them just for research.
It could be that they are not currently capable of developing much further than the 14-day mark.
Scientists might decide that this is a problem that needs to be fixed, partly for practical reasons about the limits to their usefulness. Scientists might then fix these synthetic embryos so that they could continue to develop. However, this would create a huge moral quandary.
