Not a viable fetus
In the study, the gastruloids developed into a heart and a nervous system, but not a brain or other cell types that would ensure they were capable of becoming a viable fetus. Instead, they served to study embryo development in the lab.
These structures could be the key to helping scientists unlock the mysteries of pregnancy loss and early developmental disorders, such as spina bifida. Since the structures are artificial, they bypass ethical concerns about studies on human embryos-- at least for now.
As the structures evolve, they may become life-like enough to be a cause for concern. For now, the gastruloids are enabling scientists to see human embryos in action in one of their most crucial stages: the third week.
The third week
In this time, the largely homogeneous ball of cells that is the human embryo starts to develop the specific traits of the parts it will become. So far, scientists have never been able to witness this stage as most countries make it illegal to grow embryos in a lab for research beyond 14 days after conception.
Now, that these artificial structures are mimicking this stage, scientists are taking full advantage to study it and everything that can go wrong with it. “This important finding will help us to understand the critical mechanisms of human body planning,” Li Tianqing, a developmental biologist at the Institute of Primate Translational Medicine in Yunnan, China, who also experiments with embryo-like structures, told Nature.
It should be noted that the team of researchers did not immediately jump into creating human embryo-like structures. Instead, they used past experiments creating gastruloids from mouse embryonic stem cells over the past five years to move forward into engineering structures using human cells.