Researchers from the UPF and the Memorial Sloan-Kettering Cancer Center in New York discover a mechanism that allows embryos to control their size and maintain the balance between the different cellular tissues in the first stages of development. The work, published in the journal eLife, has been coordinated by the researchers Jordi Garcia-Ojalvo and Anna-Katerina Hadjantonakis.

Embryonic development is a complex process in which millions of cells are formed from a single progenitor cell and are organized in a very precise way to give rise to different tissues and organs. To understand the self-organizing capacity of embryonic cells, the teams of Hadjantonakis and Garcia-Ojalvo have investigated the molecular control mechanisms that allow for a robust and precise self-sustained development.

The study represents a further step to understand the conditions that determine how an embryo can become a viable organism, even in the highly variable conditions in which embryos are found during pregnancy.

The researchers have studied whether mouse embryos can recover when they lose cells or when they gain them, and what mechanisms make this possible. They have observed that embryos of 50 to 150 cells in size endure well the loss of cells (eliminated by laser ablation) or their increase (by implantation of stem cells). When embryos undergo these alterations, they respond by proportionally changing the size of all their tissues. That is, after the disturbance, the differentiating progenitor cells adopt the fate necessary to restore the balance of cell types that lead to correct development.

Jordi Garcia-Ojalvo, professor of Systems Biology at Pompeu Fabra University and head of the Dynamical Systems Biology Laboratory, explains that “using a mathematical model we propose the molecular mechanism that makes the embryo so robust, and we discovered that this mechanism is based on the release of chemical signals. We have identified a growth factor, FGF4, which is key in this process”.

According to Garcia-Ojalvo, "our results illustrate how the embryo is a self-organizing system that can develop in a robust and reproducible way without the need for external inputs, and how it can be recovered after injury." The study represents a further step to understand the conditions that determine how an embryo can become a viable organism, even in the highly variable conditions in which embryos are found during pregnancy.

Reference article:

Saiz N, Mora-Bitria L, Rahman S, George H, Herder J, Garcia-Ojalvo J, Hadjantonakis A. Growth factor-mediated coupling between lineage size and cell fate choice underlies robustness of mammalian development. July 2020. DOI: 10.7554/eLife.56079.