Stem cell scientists say they have created “synthetic embryos” without using sperm, eggs or fertilization for the first time, but the prospect of using this technique to grow human organs for transplant remains remote.
The breakthrough was hailed as a major step forward, although some experts said the result could not be fully considered embryos and warned of future ethical considerations.
In research published in the journal Cell this week, scientists at Israel’s Weizmann Institute of Science said they found a way to get mouse stem cells to clump together into embryo-like structures in the laboratory
They started by collecting skin cells from mice and then made them revert to the stem cell state.
The stem cells were then placed in a special incubator designed by the researchers, which was continuously moved to mimic the mother’s uterus.
The vast majority of cells were unable to form anything.
But 50, 0.5 percent of the 10,000 total, collected 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 beating brain and heart, they added.
They were described as 95% similar to normal mouse embryos.
‘Time will tell’
If human organs could one day be grown in a laboratory, the technique could provide life-saving transplants for thousands of people each year.
Stem cell scientist Jacob Hanna, who led the research, told AFP: “The big problem with transplantation is that you have to find a matching donor and the DNA is never identical to the patient’s.”
But using the new technique, scientists could one day take cells from a patient’s liver, for example, use them to make stem cells, grow a synthetic embryo and “transplant them back into the patient” , Hanna said.
“The cell will be made from the patient, so it will be the exact DNA, no donors need to be found and there can be no rejection,” he added.
Although they were the most advanced synthetic embryo-like structures ever grown, some scientists not involved in the research cautioned against calling them “embryos.”
“These are not embryos,” French stem cell scientist Laurent David told AFP.
He preferred to call them embryoids, the name of a group of cells that resemble an embryo.
However, David welcomed the “very compelling” research, which he said could enable further experiments to understand exactly how organs are formed.
Beyond organs, Hanna said embryoids could also help identify new drug targets and potentially help find solutions for a range of problems including pregnancy loss, infertility, endometriosis and preeclampsia
“Time will tell,” he said.
Hanna, a Palestinian who led the high school research in Israel, said, “Science is my escape from the harsh reality I face while living in my homeland.”
“And I am one of the ‘luckiest'”, he added.
The first author of the Cell study is a doctoral student from the Palestinian enclave of Gaza, who needs a special permit that is periodically renewed to work at the institute in the Israeli city of Rehovot, Hanna said.
Ethical implications
Hanna has founded a company, Renewal Bio, which he said will “focus on testing potential clinical applications of human synthetic embryoids.”
He said they had ethical approval for this testing in Israel and it was legal in many other countries such as the US and the UK.
“We have to remember that synthetic embryos are embryos and not real embryos and they do not have the potential to be viable,” he said.
But researchers not involved in the study said it was too early to consider using this technique for humans.
Alfonso MartÃnez Arias of Spain’s Pompeu Fabra University said the breakthrough “opens the door to similar studies with human cells, although there are many regulatory hoops to jump through first and, from the point experimentally, human systems lag behind mouse systems.” “
And aiming to get similar results from human cells is likely to open an ethical can of worms.
“Although the prospect of synthetic human embryos is still distant, it will be crucial to engage in wider debates about the legal and ethical implications of this research,” said James Briscoe of Britain’s Francis Crick Institute.