Stem cell scientists say they have created “synthetic embryos” for the first time without using sperm, eggs or fertilization, but the prospect of using such a technique to grow human organs for transplantation remains remote.
The breakthrough has been hailed as a major step forward, although some experts said the result could not be considered fully embryos and warned of future ethical considerations.
In research published in the journal cell This week, scientists at the Weizmann Institute of Science in Israel said they have found a way for mouse stem cells to self-assemble into embryo-like structures in the laboratory.
They started by collecting cells from the skin of mice and then allowed them to revert to the stem cell state.
The stem cells were then placed in a special incubator the researchers designed, which moved continuously to mimic the womb.
The vast majority of cells formed nothing.
But 50 — 0.5 percent of the 10,000 total — clustered into spheres, then embryo-like structures, the researchers said.
After eight days — about a third of the mouse’s 20-day gestation period — there were early signs of a brain and a beating heart, they added.
They have been described as being 95% similar to normal mouse embryos.
‘We will see’
If one day human organs could be grown in a laboratory, the technology could enable life-saving transplants for thousands of people every year.
Stem cell researcher Jacob Hanna, who led the research, told AFP, “The big problem with transplantation is that you have to find a matched donor and the DNA is never identical to the patient’s.”
But with the new technique, scientists could one day, for example, take cells from a patient’s liver, use them to make stem cells, grow a synthetic embryo, and then “transplant it back into the patient,” Hanna said.
“The cell will be made from the patient, so it will be the exact DNA – no need to find donors and there can be no rejection,” he added.
Despite being the most advanced synthetic embryo-like structures ever created, some scientists not involved in the research cautioned against calling them “embryos”.
“These are not embryos,” French stem cell researcher Laurent David told AFP.
He preferred to call them embryoids, the term for a group of cells resembling an embryo.
However, David welcomed the “very convincing” research, which he says could allow for further experiments to understand exactly how organs form.
Beyond organs, Hanna says the embryoids could also help identify new targets for drugs and potentially find solutions to a range of problems including miscarriage, infertility, endometriosis and preeclampsia.
“Time will tell,” he said.
Hanna, a Palestinian who led research at the institute in Israel, said: “Science is my escape from the harsh reality I face while living in my homeland.”
“And I’m one of the ‘lucky ones,'” he added.
The first author of cell Studie is a doctoral student from the Palestinian enclave of Gaza who needs a regularly renewed special permit to work at the institute in the Israeli city of Rehovot, Hanna said.
Hanna has founded a company, Renewal Bio, which he said will “focus on testing potential clinical applications of human synthetic embryoids.”
He said they have ethical approval for such testing in Israel and it’s legal in many other countries like the US and UK
“We should remember that synthetic embryos are embryoids and not real embryos and do not have the potential to become viable,” he said.
However, researchers not involved in the study said it is still very early days to apply such a technique to humans.
Alfonso Martinez Arias of Spain’s Pompeu Fabra University said the breakthrough “opens the door to similar studies using human cells, although there are many regulatory hurdles to overcome first and human systems lag behind mouse systems from an experimental point of view. “
And the goal of achieving similar results with human cells will likely open an ethical can of worms.
“Although the prospect of synthetic human embryos is still a long way off, it will be crucial to engage in broader discussions about the legal and ethical implications of such research,” said James Briscoe of the UK’s Francis Crick Institute.
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