Understanding the inception of embryonic development is important as it may help explain why some human pregnancies fail at an early stage, however, key events after the implantation of the embryo are inaccessible as they occur in the human uterus. The use of artificial embryos rather than real ones to research the very earliest stages of human development would overcome this barrier as well as being far more ethical than using real human embryos in scientific research. Now, a study from researchers led by Cambridge University brings the development of artificial embryos a step closer by using mouse stem cells to produce artificial embryo-like structures capable of gastrulation, a key step in the life of an embryo. The team states their artificial embryos underwent the most important event in life in the culture dish, and are now extremely close to real embryos. The study is published in the journal Nature Cell Biology.
Earlier studies from the group developed a much simpler structure resembling a mouse embryo on a 3D jelly scaffold, using two types of the body’s master building blocks or stem cells. However, a key step in the life of the embryo, namely gastrulation was missing. Gastrulation is the point when the embryo transforms from being a single layer to three layers, these are the inner layer (endoderm), middle layer (mesoderm) and the outer layer (endoderm), determining the tissues or organs the cells will develop into. The current study develops the embryo-like structures further, using three types of stem cells instead of two, allowing them to reconstruct gastrulation.
The current study adds primitive endoderm stem cells (PESCs) to enable the artificial embryo to undergo gastrulation, where it organizes itself into the three body layers, reflecting that of natural embryonic development. To develop further, they would have to implant the embryo into the body of the mother or an artificial placenta. Results show by replacing the jelly used in earlier experiments with this third type of stem cell, the team was able to generate structures whose development was astonishingly successful.
The lab states they should now be in a better position to understand how the three stem cell types interact with each other to enable embryonic development. This was achieved by altering the biological pathways in one cell type to gauge how this affects the behavior of one, or both, of the other cell types. They go on to add the early stages of embryonic development are when a large proportion of pregnancies are lost, and now the medical community has a way of simulating embryonic development in the culture dish, it should be possible to understand exactly what is happening during this period.
The team surmises they have successfully developed artificial embryos from stem cells capable of undergoing the crucial life event of gastrulation. For the future, the researchers state they can now try to apply this to the equivalent human stem cell types and study the very earliest events in human embryonic development without actually having to use natural human embryos.
Source: University of Cambridge Research
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