Image Credit: Science Photo Library - ZEPHYR 
Researchers in the UK have managed to produce synthetic lab-grown human embryos from stem cells without the need of sperm or an egg, in a development hailed as a scientific milestone despite serious concerns over ethical implications.
Scientists with the University of Cambridge announced their findings at a yearly meeting of the International Society for Stem Cell Research in Boston Wednesday, with foremost researcher Prof. Magdalena Zernicka-Goetz declaring, “We can create human embryo-like models by the reprogramming of [embryonic stem] cells.”
The Guardian explains the scientific process involved in formulating the synthetic embryo via stem cells:
Previously, Żernicka-Goetz’s team and a rival group at the Weizmann Institute in Israel showed that stem cells from mice could be encouraged to self-assemble into early embryo-like structures with an intestinal tract, the beginnings of a brain and a beating heart. Since then, a race has been under way to translate this work into human models, and several teams have been able to replicate the very earliest stages of development.
… speaking at the conference, Żernicka-Goetz described cultivating the embryos to a stage just beyond the equivalent of 14 days of development for a natural embryo.
The model structures, each grown from a single embryonic stem cell, reached the beginning of a developmental milestone known as gastrulation, when the embryo transforms from being a continuous sheet of cells to forming distinct cell lines and setting up the basic axes of the body. At this stage, the embryo does not yet have a beating heart, gut or beginnings of a brain, but the model showed the presence of primordial cells that are the precursor cells of egg and sperm.
Scientists are currently allowed by law to cultivate embryos only up to 14 days to investigate the “black box” period of embryonic cell development.
After two weeks, scientists switch over to donated embryos and pregnancy scans to further their research.
Francis Crick Institute Stem Cell Biology professor Robin Lovell-Badge explained, “The idea is that if you really model normal human embryonic development using stem cells, you can gain an awful lot of information about how we begin development, what can go wrong, without having to use early embryos for research.”
It’s also still unclear whether the lab-produced embryos could actually develop in the womb, as previous experiments to implant the embryos in mice have failed.
The Guardian notes:
There is also a significant unanswered question on whether these structures, in theory, have the potential to grow into a living creature. The synthetic embryos grown from mouse cells were reported to appear almost identical to natural embryos. But when they were implanted into the wombs of female mice, they did not develop into live animals. In April, researchers in China created synthetic embryos from monkey cells and implanted them into the wombs of adult monkeys, a few of which showed the initial signs of pregnancy but none of which continued to develop beyond a few days.
While scientists have still not been able to achieve advanced stages of embryo maturation, the research appears to be getting closer to finding the missing links, raising ethical concerns as it’ll soon be advancing beyond the boundaries of current legislation.
The research is also forcing the scientific community to debate the potential implications of manipulating human-like structures outside the confines of natural reproduction.
“If the whole intention is that these models are very much like normal embryos, then in a way they should be treated the same,” Lovell-Badge told the Guardian. “Currently in legislation they’re not. People are worried about this.”
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