PARIS — Scientists have used stem cells to create structures that look like human embryos in the lab, in a first that has sparked calls for stricter regulation in this rapidly evolving field.
Several different labs around the world have released pre-print studies in the past seven days outlining their research, which experts say should be treated with caution as the research has not yet been peer-reviewed.
The labs have used different techniques to encourage human embryonic stem cells, which can become any type of cell, to self-assemble into a structure that resembles an embryo – without the need for sperm, egg or of fertilization.
The goal is to give scientists a model with which to study human embryos in a way never possible due to ethical concerns, in hopes of gaining new insights into the causes of birth defects, genetic disorders, infertility and other problems during pregnancy.
The first announcement came last Wednesday, when Magdalena Zernicka-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 from the Weizmann Institute of Science in Israel published a pre-print study detailing their own work on stem cell-based models of human embryos.
The Zernicka-Goetz team then quickly released their own preprint, giving more information. Other labs based in China and the United States have followed suit, releasing pre-prints late last week.
The researchers pushed back against media reports calling the clumps of cells “synthetic embryos”, saying they are neither strictly synthetic, that they grew from stem cells, nor should they be considered embryos.
The wealth of data has highlighted the highly competitive nature of research in this area.
Just weeks apart in August last year, Zernicka-Goetz and Hanna’s teams published articles about their work creating the first embryo-like structures using mouse stem cells.
Both teams told AFP that their new studies had been accepted by prestigious peer-reviewed journals – and that they had presented their work at conferences months before recent media attention.
Hanna dismissed the idea that either team was “first”, saying they achieved quite different feats.
He told AFP that his models had a “placenta, yolk sac, amniotic cavity” and other embryonic features that he said Zernicka-Goetz structures lacked.
Other researchers seemed to agree that Hanna’s models were more advanced, also praising her team for only using chemical, not genetic, modifications to coax cells into embryo-like structures.
“The similarity (of Hanna’s model) to the natural embryo is remarkable, almost uncanny,” said Jesse Veenvliet, a researcher at the Max Planck Institute for 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 research.
But “the impact of both studies is immense,” he added.
“We should try to avoid unhealthy hype since this technology is at an early stage – 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 the lab in many countries.
After 14 days, the embryos begin to organize cells to form organs, including the brain, a period called the “black box” because little is known about human embryos beyond this point.
Regulations for research in this area differ from country to country, but most apply to embryos that have been fertilized – a loophole that new embryo-like models are slipping through.
The University of Cambridge announced on Friday that it has launched a project to develop the first governance framework for stem cell-based human embryo models in the UK.
The scientists involved stressed that they had no intention of implanting their model embryos into a human uterus – and that even if done, it would not lead to a baby.
A model embryo implanted in a female macaque in previous research induced some signs of pregnancy but did not survive, Widera said.
James Briscoe of the UK’s Francis Crick Institute called on researchers to “proceed with care, prudence and transparency”.
“The danger is that missteps or unwarranted assertions will have a chilling effect on the public and policy makers, it would be a major setback for the field.”
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