Scientists involved in the research said the aim is not to create mice or babies outside the womb, but to understand how organs develop in embryos and use that knowledge to develop new ways to heal people. .
From a group of embryonic stem cells, scientists at the Weizmann Institute of Science created synthetic embryos, similar to real mouse embryos, with a primary beating heart, blood circulation, folded brain tissue and intestinal tract. Mouse embryos developed in an artificial womb and stopped developing after eight days, about a third of mouse pregnancies.
A decade of progress comes in a field filled with efforts to develop embryonic models from human and mouse cells. Scientists can use such models to observe early stages of embryonic development and study the formation of organs.
But as models become more resembling the real thing, they also open up ethically ambiguous territory. At what point do artificial embryos become so similar to the real object that they are subject to the same protection as real embryos?
“This is an important milestone in our understanding of how embryos build themselves,” Alfonso Martínez Arias, a developmental biologist at Pompeu Fabra University in Barcelona who is not involved in the research, said in an email. He called the experiment a “game changer.”
research, published on Monday journal cell, far from growing a rat outside the womb, much less than a human. This was a proof of concept that a fully synthetic embryo could be assembled from embryonic stem cells, and while the researchers were successful, it was a highly error-prone process, with only a small fraction of the embryo being the beginning of one. was on the way to develop. The beating of the heart and other organs.
Although synthetic mouse embryos were identical to natural mouse embryos, they were not exactly identical and did not result in pregnancies in real mice, according to Jacob Hanna, a stem cell scientist at the Weizmann Institute of Science, who led the study. Work.
Stanford Law bioethicist Henry T. Greeley said, “This is an interesting next step, not shocking, but one that makes a proposal with broader implications far more practical in the long run: living any mouse cell.” Possibility to turn into a mouse.” school.
research, like no other recent research, putting the possibility of a full human synthetic embryo on the horizon, several researchers said, is necessary to continue a societal discussion about how these entities should be handled. Last year, the International Society for Stem Cell Research announced a historic relaxation “14 day rule” That said, researchers can grow natural embryos for only 14 days in the lab, allowing researchers to gain approval for longer studies. Human embryo models are banned from being implanted in the uterus.
“The mouse is a starting point for thinking about how one might want to look at this in humans,” said Alex Meisner, a stem cell biologist at the Max Planck Institute for Molecular Genetics. “There is no need to worry or panic, but … as we learn, it is important to discuss in parallel: How far do we want to take this?”
Hanna said her hope is that the technology could be used not as a replacement for reproduction but as a way to create synthetic human embryo models, which could result in precursors of organs that could be studied and could potentially be used therapeutically.
For decades, the major hope for stem cell therapy has been the repair of the body’s own tissues. Stem cells can grow in any tissue or organ, so the ability to use those cells to treat spinal cord injuries, patch damaged hearts or diabetes has been fascinating. But turning those cells into complex, functioning tissue has been a challenge. Hannah hopes that seeing this process unfold during early development will provide important clues.
“Our goal is not to create a pregnancy outside the uterus, whether it’s mice or whatever species,” Hanna said. “We are having difficulties actually making organs – and to make stem cells into organs, we need to learn how the embryo does that. We started with this because the uterus is a black box – it is transparent. Not there.”
Hanna has founded a company, Renewal Bio, which plans to use the technology clinically. One potential use would be to take skin cells from a woman with fertility problems, reprogram those cells to make stem cells, and then develop synthetic embryo models that can be used to produce eggs.