One of the fundamental questions in biology is how cells organize themselves to form complex structures in living organisms. Researchers have made significant progress in unraveling this mystery by studying gastrulation, a crucial stage in embryo development. Gastrulation is the process by which cells transition from a single layer to a multidimensional structure with a main body axis. In humans, this occurs approximately 14 days after conception.

Scientists from the University of California San Diego, the University of Dundee (UK), and Harvard University turned to chick embryos as a model system to investigate gastrulation. Although studying human embryos at this stage is impossible, chick embryos share many similarities with their human counterparts.

The research team, led by UC San Diego Assistant Professor of Physics Mattia Serra, employed an interdisciplinary approach combining theoretical and experimental science. Serra, a theorist interested in emergent patterns in biophysical systems, collaborated with biologists from the University of Dundee to build a mathematical model based on experimental data.

Remarkably, the mathematical model accurately predicted the motion of tens of thousands of cells during gastrulation in the chick embryo, as observed under a microscope. This is the first time a self-organizing mathematical model has successfully reproduced these cellular flows in chick embryos.

The biologists wanted to test the model’s predictive capabilities to validate it further. They perturbed the model by altering the initial conditions or parameters to simulate different scenarios. Surprisingly, the model generated cellular flows that were not naturally observed in chick embryos but were observed in two other vertebrate species: frogs and fish.

To confirm these unexpected results, the biology collaborators replicated the perturbations from the model in the lab using chick embryos. Astonishingly, the manipulated chick embryos exhibited gastrulation flows naturally observed in fish and frogs.

The findings, published in Science Advances, suggest that the physical principles underlying multicellular self-organization may have evolved across vertebrate species. Despite living in different environments, the evolutionary pressure over time may have led to changes in the parameters and initial conditions of embryo development. However, the core principles of self-organization during early gastrulation stages may remain the same across species.

Serra and his collaborators are now investigating other mechanisms that contribute to self-organizing patterns at the embryo scale. They hope that this research will advance the fields of biomaterials design and regenerative medicine, ultimately leading to longer and healthier lives for humans.

In summary, this groundbreaking study sheds light on the intricate process of gastrulation and its role in embryo development. Using chick embryos as a model system, scientists have developed a mathematical model that accurately predicts cellular flows during gastrulation. Surprisingly, the model also generated flows observed in other vertebrate species. These findings suggest that the fundamental principles of self-organization during gastrulation may be conserved across different organisms. This research opens new avenues for understanding embryonic development and has potential implications for biomaterials design and regenerative medicine.

References

• Franklin, M. & University of California-San Diego. (2023, December 6). A mathematical model connects the evolution of chickens, fish and frogs. Phys.Org; University of California-San Diego. https://phys.org/news/2023-12-mathematical-evolution-chickens-fish-frogs.html
• Serra, M., Serrano Nájera, G., Chuai, M., Plum, A. M., Santhosh, S., Spandan, V., Weijer, C. J., & Mahadevan, L. (2023). A mechanochemical model recapitulates distinct vertebrate gastrulation modes. Science Advances, 9(49), eadh8152. https://doi.org/10.1126/sciadv.adh8152