“These synthetic embryo models had all the structures and compartments characteristic of this stage, including the placenta, yolk sac, chorionic sac and other external tissues that ensure the models’ dynamic and adequate growth,” the researchers have said.
Textbook image of a human day-14 embryo
To prepare the model of the human embryo, which is “a textbook image of a human day-14 embryo” the stem cells were transformed into four types of cells: epiblast, hypoblast, extraembryonic mesoderm and trophoblast. 120 of these four types of cells were mixed in a fixed ratio. The epiblast cells became the embryo, the trophoblast cells becamse the placenta, the hypoblast cells became the supportive yolk sac and the extraembryonic mesoderm cells together helped form the embryo.“This is the first embryo model that has structural compartment organisation and morphological similarity to a human embryo at day 14,” Prof Jacob Hanna, the lead researcher told the Guardian. At two weeks, the balls of cells were about half a millimetre wide.
This can open up new doors to study the impact and effect of medicines on real human embryos as in many clinical trials pregnant women are excluded. Another important application can be, the researchers say is the creation of embryos from the skin cells of ill patients. “Grow the model embryos for a month or so and they will start to develop organs that can be used as a source of cells to transplant into the patients,” Prof Hanna told the media. “Do they have the right to give their own skin cells to make an embryo model and make cells that will save their lives or solve their medical need? That is the scenario that should be considered,” Hanna told the Guardian. Before growing a model embryo for donor tissue, scientists would tweak its genetics to ensure it did not develop a brain or nervous system, he added.
The research has been published in Nature.