Scientists have used stem cells to create structures that resemble human embryos in the laboratory, a first that calls for tighter controls on rapidly advancing stem cell research.
Various labs around the world have published pre-print studies in the past seven days describing their research, which experts say should be treated with caution because the research has not yet been peer-reviewed.
The labs used a variety of techniques to encourage human embryonic stem cells, which can develop into any type of cell, to self-assemble into an embryo-like structure — without the need for sperm, an egg or fertilization.
The goal is to give scientists a model with which ethical concerns have prevented them from studying human embryos, hoping to gain new insights into the causes of birth defects, genetic disorders, infertility and other problems during pregnancy.
The first announcement came last Wednesday, when Magdalena Zernica-Goetz of the University of Cambridge and the California Institute of Technology described her team’s work at the annual meeting of the International Society for Stem Cell Research in Boston.
His presentation was first reported by The Guardian newspaper.
On Thursday, Jacob Hanna’s team at the Weizmann Institute of Science in Israel published a pre-print study detailing their own work on stem cell-based human embryo models.
The Zernicka-Goetz team quickly published a preprint of their own, giving more information. Other labs based in China and the US have followed suit, releasing preprints late last week.
Researchers have pushed back against media reports that call the clusters of cells “synthetic embryos,” saying they are not strictly synthetic, grown from stem cells, or should not be considered embryos.
‘almost unusual’
The flurry of data highlights the highly competitive nature of research in this field.
Within weeks of each other in August last year, both Zernica-Goetz and Hanna’s team published papers on their work on creating the first embryo-like structures using stem cells from mice.
Both teams told the AFP news agency that their new research had been accepted by prestigious peer-reviewed journals – and that they had presented their work at the conference months before the recent media attention.
Hanna rejected the idea that both groups were “firsts”, saying they achieved quite different feats.
He told AFP that his models included a “placenta, a yolk sac, amniotic cavity” and other fetal features that he said lacked Zernica-Goetz structures.
Other researchers felt Hanna’s models were more advanced, also praising her team for using only chemicals, not genetic modification, to turn cells into embryo-like structures.
“Similarity [of Hanna’s model] “Extraordinary, almost abnormal, to a natural embryo,” said researcher Jesse Vinvlit of the Max Planck Institute of Molecular Cell Biology and Genetics in Germany.
Darius Widera, an expert in stem cell biology at the University of Reading in the UK, told AFP it was best to wait for peer review before comparing studies.
But “the implications of both studies are immense”, he added.
“We should try to avoid unhealthy publicity since this technology is in its infancy – but already, new guidelines are going to be needed.”
Inside the ‘black box’?
Both labs said they developed their embryo models for 14 days, the legal limit for growing human embryos in labs in many countries.
After 14 days, the embryo begins organizing cells to form organs, including the brain, a period called the “black box” because little is known about the human embryo beyond that point.
Regulations for research in this area differ between countries but mostly apply to embryos that have been fertilized – new models like an embryo hatched.
Cambridge University said on Friday it had launched a project to develop the first governance framework for stem cell-based human embryo models in the UK.
The scientists involved emphasized that they did not intend to implant their embryo models into human wombs – and even if they did, it would not produce a baby.
An embryo model implanted into a female macaque as part of previous research induced some signs of pregnancy, but did not survive, Wiedera said.
James Briscoe of Britain’s Francis Crick Institute urged researchers to “proceed cautiously, cautiously and transparently”.
“The danger is that missteps or unwarranted claims will have a chilling effect on the public and policymakers, a major blow to the field.”
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