By Patrick Yang ’20

Embryo development has been a very limited and sanctioned field of research due to concern for the pregnant mother. Although safety is a priority for live subjects, research in this area could improve understanding of optimal prenatal conditions, as well as the molecular interactions between embryonic stem cells. Researchers have thus entertained the idea of an artificial embryo because it would allow scientists to freely manipulate prenatal conditions while avoiding safety concerns. In an effort to achieve the creation of an artificial embryo, researchers have, for the first time, combined murine stem cells in a 3-D scaffold to completely resemble a natural developing embryo.

Dr. Magdalena Zernicka-Goetz of the University of Cambridge and her team’s recent research combined both embryonic stem cells (ESCs) and extra-embryonic trophoblast stem cells (TSCs) in a 3-D scaffold of extracellular matrix and growth medium to support stem cell growth. Previous research had primarily used only ESCs, the cells that compose the embryo. However, those attempts were not successful because close interaction and coordination with TSCs, the cells that form the extra-embryonic tissue (placenta and yolk sac), is required for proper embryo development. In order to properly imitate the spatial and temporal sequence of natural embryo development, single ESCs, taken from pregnant 6-week old female mice, were paired with small clumps of TSCs in the 3-D scaffold to allow their interaction. After 96 hours, reorganization of the stem cells formed an “egg” cylinder with a central cavity, in which the embryo can develop, and ESCs and TSCs at opposite ends, which resembles natural embryo development. Researchers then evaluated the artificial embryo’s tissue volume and cell count to confirm its resemblance to a natural embryo.. Reproducibility of the experiment turned out to be very high with a 92.68% (n=88) success rate in forming the cylindrical structure – affirmation that the artificial embryo barely differed from a natural embryo.

The development of this new technique serves a strong purpose in observing a very critical stage of human development. Researchers are now able to thoroughly explore and understand the development process and birth defects without worrying about the usual safety precautions.

References:

1. S.E. Harrison, et al., Assembly of embryonic and extra-embryonic stem cells to mimic embryogenesis in vitro. Science (2017). doi: 10.1126/science.aal1810.
2. Image retrieved from: https://upload.wikimedia.org/wikipedia/commons/thumb/6/6b/Embryo%2C_8_cells.jpg/300px-Embryo%2C_8_cells.jpg