Scientists Debut Lab Models of Human Embryos

Carl Zimmer writes in The New York Times: In its first week, a fertilized human egg develops into a hollow ball of 200 cells and then implants itself on the wall of the uterus. Over the next three weeks, it divides into the distinct tissues of a human body. And those crucial few weeks remain, for the most part, a black box. "We know the basics, but the very fine details we just don't know," said Jacob Hanna, a developmental biologist at the Weizmann Institute of Science in Israel. Dr. Hanna and a number of other biologists are trying to uncover those details by creating models of human embryos in the lab. They are coaxing stem cells to organize themselves into clumps that take on some of the crucial hallmarks of real embryos. This month, Dr. Hanna's team in Israel, as well as groups in Britain, the United States and China, released reports on these experiments. The studies, while not yet published in scientific journals, have attracted keen interest from other scientists, who have been hoping for years that such advances could finally shed light on some of the mysteries of early human development. Ethicists have long cautioned that the advent of embryo models would further complicate the already complicated regulation of this research. But the scientists behind the new work were quick to stress that they had not created real embryos and that their clusters of stem cells could never give rise to a human being. "We do it to save lives, not create it," said Magdalena Zernicka-Goetz, a developmental biologist at the University of Cambridge and the California Institute of Technology, who led another effort. [...] If scientists can create close, reliable models of embryos, they will be able to run large-scale experiments to test potential causes of pregnancy failures, such as viral infections and genetic mutations. The models could lead to other medical advances too, noted Insoo Hyun, a member of the Harvard Medical School Center for Bioethics who was not involved in the new studies. "Once you get the embryo models in place and you can rely on them, that can be an interesting way to screen drugs that women take when they're pregnant," he said. "That would be an enormous benefit." Dr. Hanna [...] also saw a possibility of using embryo models as a new form of stem-cell treatment for diseases such as cancer.

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