New Stem Cell Model Sheds Light on Early Embryo Development

Researchers at the University of Michigan Medical School have enhanced a widely used stem cell model, opening the door to deeper understanding of early embryonic development. Led by Ph.D. candidate Bohan Chen in the lab of Professor Idse Heemskerk from the Department of Cell and Developmental Biology, the team’s work offers a significant step forward in studying critical developmental stages without the ethical complexities of using actual embryos.

Their findings, recently published in Nature Methods, demonstrate how a refined version of a model called a gastruloid can better mimic the early processes of human development. Gastruloids are simplified, two-dimensional structures created from stem cells and grown in vitro. They replicate early developmental events such as gastrulation—when the embryo’s basic body plan begins to take shape—without the potential to form a viable human being.

Gastrulation involves the emergence of three primary cell layers: the ectoderm, which forms the skin and nervous system; the mesoderm, which gives rise to internal organs like the heart and muscles; and the endoderm, which becomes the gastrointestinal tract and lungs. Traditionally, cultured gastruloids could only be maintained for about two days before the cells lost organization and development ceased.

To overcome this limitation, Chen and colleagues modified the culturing environment using new media and other refinements. The result was a more stable and longer-lasting model. "When we tried growing the cells for more than two days, it actually worked and did some really interesting things," said Heemskerk.

One of the most striking observations was the behavior of the mesoderm cells. In the improved model, these stem cells began migrating underneath the original cell layer, forming a multi-layered structure similar to what occurs in natural embryos. This movement is notoriously difficult to visualize—even in animal models like mice.

Even more intriguingly, the team found that the mesoderm cells’ migration was not random. The cells moved inward from the edges toward the center, suggesting the presence of directional cues. “There’s something—we don’t yet know what—telling them which way to go,” Heemskerk explained. “We now have a setup in which we can figure out what is guiding their movement.”

Understanding these migration patterns could provide critical insights into developmental disorders, such as congenital heart defects. Further investigation revealed that mesoderm cells within gastruloids are not uniform; instead, they consist of distinct subtypes that express different genes. Using fluorescence imaging, the researchers were able to visualize these gene expression patterns, which may help predict the organs the cells are destined to form.

This discovery raises an important developmental biology question: Do cells determine their fate before migration, or is it dictated by their final position? Heemskerk and his team aim to explore this and other questions using their enhanced model.

“This is a simple model that allows us to see things that would be very difficult in a complex 3D structure,” said Heemskerk. “It captures essential biological phenomena while avoiding the ethical concerns associated with working on actual embryos.”

With this innovation, the team hopes to further unravel the mysteries of early human development and the roots of developmental disorders.

Source:https://phys.org/news/2025-05-embryo.html

This is non-financial/medical advice and made using AI so could be wrong.