Human embryonic stem cells (hESCs) have transformed our understanding of biology and development.
These remarkable cells can become every cell type in the human body. That ability makes them an invaluable tool for studying disease, testing therapies, and exploring how life begins.
Yet researchers face important limitations when working with embryonic stem cells.
Human embryonic stem cell lines originate from donated embryos created through in vitro fertilization. Researchers also face strict limits on how long they can study developing embryos in the laboratory.
Now, researchers at Caltech have developed a new stem cell model that could help overcome some of those challenges.
Building Embryo-Like Structures in the Lab
The research team, led by Magdalena Zernicka-Goetz, used expanded pluripotent stem cells, or EPSCs, to create three-dimensional structures that mimic some features of early human embryos.
EPSCs originate from embryonic cells but can be maintained and expanded in the laboratory.
The researchers found that these cells retained a form of developmental “memory.”
That memory allowed the cells to organize themselves into structures that resemble key stages of early embryonic development.
Specifically, the cells displayed characteristics known as polarization and cavitation.
These processes play critical roles during the earliest phases of embryo formation.
A New Tool for Studying Early Human Development
According to Zernicka-Goetz, the study highlights the remarkable ability of early embryonic cells to self-organize.
“The ability to assemble the basic structure of the embryo seems to be a built-in property of these earliest embryonic cells,” she said.
While the models do not perfectly replicate human embryonic development, they capture important biological features that researchers can study in the laboratory.
The team believes further refinements could improve how accurately these structures mimic natural development.
That progress could provide researchers with a powerful new system for investigating some of the earliest stages of human life.
Expanding the Possibilities of Stem Cell Research
Generating embryo-like structures in the laboratory offers several advantages.
Researchers can create large numbers of these models without relying on newly donated embryos.
The approach also allows scientists to study developmental events that remain difficult to observe directly.
Understanding those early processes has important implications for both basic science and medicine.
Many questions about human development remain unanswered. Researchers still know relatively little about how cells organize themselves into tissues and organs during the earliest stages of life.
The authors believe this platform could help address those gaps in knowledge.
They wrote that understanding human development remains both a biological and clinical priority. The new system provides a valuable framework for developing more sophisticated embryogenesis models.
Looking Ahead
This research represents another example of how stem cell science continues to expand the tools available to researchers.
By creating laboratory models that mimic key aspects of early development, scientists can explore fundamental questions without many of the limitations associated with studying human embryos directly.
While additional work remains, these embryo-like structures could help researchers better understand development, fertility, congenital disorders, and the biological processes that shape human health from the very beginning.
The findings were published in the journal Nature Communications.
Most pregnant women experience sudden and dramatic increase in estrogen and progesterone. Both estrogen and progesterone play major roles to maintain well being of pregnancy women. Estrogen has critical roles to maintain health of pregnant women, fetus development and maturation. Whereas, progesterone stimulates thickening of uterine lining for implantation of fertilized egg and transforming uterus from small size of pear into uterus can accommodate a full term baby. Several other hormones have been identified during pregnancy. These are: 1)Human chorionic gonadotropin hormone stimulate ovaries to produce estrogen and progesterone continuously during development of the embryo. 2)Human placental lastogen also known as human chorionic somatomammotropin has role to provide nutrition to the fetus. Thus, ovary and placental produce several hormones to maintain the health of pregnant women. Evidence showed that estrogen levels increase steadily during pregnancy and reach peak in their trimester. However, progesterone is extraordinary high during pregnancy to maintain the well being of pregnant women and fetus. The changes in the level of hormones have greater impact on growth factors production during development of fetus. The embryo requires growth factors to support the formation of internal organs, external structures, elongation of neural tube, vascularization and brain development.
The process of embyogenesis in human embryo requires growth factors to develop into different parts of tissues and organs. Embryo in vivo depends on placental to provide a variety of growth factors to support fetus growth and differentiation. This is not seen in in vitro model, the limited supply of growth factors causes defect in tissues and organs development. Evidence showed that maturation of embryo stem cells requires many stages of growth and differentiation to produce mature and functioning cells. Each stage of maturation, the progenitors respond to different growth factors and turn on the specific gene for expression. Lack of specific growth factor in anyone stage of maturation may result in prematurely development of tissues and organs. Thus, human placental becomes a focus of extensive investigation to determine specific growth factors regulate each stage of fetus development.