If all goes well, the human embryo implants in the uterus about seven days after fertilization. At this point, the embryos become unusable for research due to technical and ethical constraints. That’s why scientists have developed stem cell models of various types of embryonic and extraembryonic cells to study human development in petri dishes.
A research team led by Vincent Pasque has developed the first model for a specific type of human embryonic cells, the extraembryonic mesoderm cells. Prof Pasque said: “These cells produce the first blood in the embryo, help the embryo to attach to the future placenta and play a role in forming the primitive umbilical cord. In humans, this type of cell appears more often than in mouse embryos. Early developmental stages, and there may be other important differences between species. This makes our model particularly important: studies in mice may not give us the same answers that apply to humans.”
The researchers made their model cells from human stem cells that can still develop into all cell types of an embryo. These new cells closely resemble their natural counterparts in human embryos and are therefore a good model for this particular cell type.
“You don’t make a new human cell type every day,” Pasque said. “We are very excited because now we can study processes that are normally inaccessible during development. In fact, this model has already allowed us to find the source of extraembryonic mesoderm cells. In the long term, our model will also hold promise for Medical challenges such as fertility problems, miscarriages and developmental disorders provide additional insights.”