Scientists Create Synthetic Mouse Embryos
Stem cell researchers in Israel have created synthetic mouse embryos without using a sperm or egg, then grown them in an artificial womb for eight days, a development that opens a window into a fascinating, potentially fraught realm of science that could one day be used to create replacement organs for humans. The Washington Post reports: The objective, scientists involved with the research said, is not to create mice or babies outside the womb, but to jump-start the understanding of how organs develop in embryos and to use that knowledge to develop new ways to heal people. From a clump of embryonic stem cells, scientists at the Weizmann Institute of Science created synthetic embryos that closely resembled real mouse embryos, with rudimentary beating hearts, blood circulation, folded brain tissue and intestinal tracts. The mouse embryos grew in an artificial womb and stopped developing after eight days, about a third of a mouse pregnancy. The research, published Monday in the journal Cell, is far from growing a mouse, much less a human, outside the womb. It was a proof of concept that a complete 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 embryos going on to develop the beginnings of a beating heart and other organs. Although the synthetic mouse embryos bore a close resemblance to natural mouse embryos, they were not exactly the same and did not implant or result in pregnancies in real mice, according to Jacob Hanna, the stem cell scientist at the Weizmann Institute of Science who led the work. The research, like other recent studies, puts the possibility of a complete human synthetic embryo on the horizon, several researchers said, making it necessary to continue a societal discussion about how these entities should be handled. Last year, the International Society for Stem Cell Research relaxed a historical "14-day rule" that said researchers could grow natural embryos for only 14 days in the laboratory, allowing researchers to seek approval for longer studies. Human embryo models are banned from being implanted into a uterus.
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