Oct 3, 2022 – A miscarriage is a devastating, albeit natural, event. The experience of nearly a million pregnant women in the United States Abortion every yearAccording to the National Advocates for Pregnant Women. New research could provide insight into the causes of some types of early pregnancy loss and may one day help prevent miscarriages.
In a bioengineering breakthrough, scientists have created a mouse embryo in a lab without using sperm or eggs. The experimental embryo, called the model, grew from stem cells and was further developed than any previous experiments, with a beating heart and a brain base inside a yolk sac, according to the researchers.
The experiment, while being conducted using mouse stem cells, could help explain why some pregnancies fail in humans. Miscarriages occur in up to 15% of pregnancies confirmed by doctors. According to some studies, as well as for many pregnant women even before they know about the pregnancy. This experiment gives researchers a glimpse into a critical growth stage for the first time.
Lead researcher Magdalena Zernica Goetz, Ph.D., says, Professor of Mammalian Development and Stem Cell Biology at the University of Cambridge, UK “That’s why they tell us about the real pregnancy.”
Using the new mouse models, researchers can study implantation, the stage at which embryos implant themselves into the mother’s body — a stage at which embryos are often difficult to survive. The same process occurs in mouse embryos, which develop very similarly to human embryos at this early stage of life.
Decoding the stem cell code
Six years ago, researchers from the University of Cambridge and California Institute of Technology To create models that would allow them to study fetal development in 3D but without the need for human embryos.
“We try to understand the key principles of time and place that must be fulfilled” to form a successful pregnancy, Zernicka-Goetz explains. “If these principles are not met, the pregnancy is terminated, even before the women know they are pregnant.”
there border On the use of human embryos in research, previous experiences have tended to replicate only one aspect of development. This led to two-dimensional experiments: flat cells at the bottom of a petri dish that lack the structural organization of real tissue.
The new 3D models have beating hearts and yolk sacs in which embryos feed and grow. Models have even advanced to shape the beginning of the brain – research first.
The scientists used basic cellular “building blocks” called stem cells and were able to make the cells communicate along a time line that mimics normal development, and mimics these developmental stages, says Zernica Goetz. These “building blocks” are actually three types of stem cells: pluripotent stem cells that build body tissues, and two other types of stem cells that build the placenta and the amniotic sac.
Completing the experiment requires the correct amount of each type of stem cell. The researchers also needed to understand how these cells exchange information before they start growing. Zernica Goetz says the researchers were able to “decode” the way cells talk to each other.
At first, the three types of stem cells unite, almost like a soup, but when the time is right, they must recognize each other and sort themselves. Next, each type of stem cell must begin to build a different structure necessary for the growth of the fetus. Zernicka-Goetz believes this construct is human tissue engineering.
With the new technique, researchers can continue to investigate into the transplant stage and beyond. And they did — modifying the experiment to intentionally create a genetically defective embryo.
Goetz and her team eliminated a specific gene known to regulate how cells create their own identities. Doing so has resulted in the same defects in brain development as in human embryos, providing “proof of concept” that experimental models can be used to study other genetic puzzles, she says.
Scientists still aren’t sure what some of the genes do, as well as at what point these genes become crucial to brain development.
“Many genes have very early roles in determining, for example, head position, as well as how our brain functions,” says Zernica Goetz. “We can now use this model system to assess the function of those genes.”