Researchers generate crucial life event in artificial mouse embryo.
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 state that 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 in culture, using two types of stem cells, the body’s master cells, and a 3D jelly scaffold on which they can grow. However, a key step in the life of the embryo, namely gastrulation was missing. Gastrulation is the point at which the embryo transforms from being a single layer to three layers: an inner layer (endoderm), middle layer (mesoderm) and outer layer (endoderm), determining which 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, which allows them to reconstruct gastrulation.
The current study adds primitive endoderm stem cells (PESCs) which enable the artificial embryo to undergo gastrulation, organising itself into the three body layers which all animals have, reflecting that of natural embryonic development; to develop further, they would have to implant into the body of the mother or an artificial placenta. Results show that by replacing the jelly used in earlier experiments with this third type of stem cell, the team were able to generate structures whose development was astonishingly successful.
The lab states they should now be in a position to better understand how the three stem cell types interact to enable the embryo to develop, by experimentally altering biological pathways in one cell type and seeing how this affects the behaviour of one, or both, of the other cell types. They go on to add that the early stages of embryonic development are when a large proportion of pregnancies are lost, and now the medical community have 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 surmise that they have successfully developed artificial embryos from stem cells capable of undergoing the crucial life event of gastrulation. For the future, the researchers state that 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