Short-Time Attractors Guide Embryonic Cell Movement

Cells divide rapidly and migrate in a highly ordered manner to form the skeleton, organs, and other vital systems as embryos develop from conception to birth. But how do cells know when and how to move to create a fully developed, complex living organism? This question poses a significant challenge for scientists.

Mattia Serra, an Assistant Professor of Physics at the University of California, San Diego, and colleagues at Politecnico di Milano (Italy) have developed a new technique to manipulate the movement of embryonic cells using short-time attractors. Serra had previously developed and adopted this concept to aid in maritime search and rescue operations. This work aims to help uncover the answer. The research was published in the journal Physical Review Letters.

Structures known as “short-time attractors” have a momentary effect on a system's dynamics and motion but do not shape its long-term characteristics. The researchers were able to direct cell accumulation to specific regions of the embryo by manipulating the spatial distribution of myosin, the molecular motor that propels cell migration.

The embryo is propelled by myosin, but it is also subjected to external forces and disturbances that tug and push on its cells. Rather than being under the embryo's control, these disruptions are imposed upon it.

This dance is quite delicate. For cells to move toward the attractors required for development and to cope with the imposed perturbations, the embryo must distribute myosin optimally.

The researchers developed an ideal control technique using theory and simulations to generate and direct short-time attractors in flows resembling those seen in embryonic development.

Colleagues in the Weijer group at the University of Dundee (Scotland) changed a chick embryo's myosin distribution to validate their notion. The major body axis forms when the embryo normally develops a short-time attractor as a line.

According to Serra's predictions, if their myosin had a specific distribution, they might form a ring-shaped short-time attractor. The Weijer group successfully used the proposed myosin distribution in a living embryo, and instead of a linear attractor, a circular one was created.

This new approach to directing cell flows may be useful in regenerative medicine and in the fabrication of artificial organs and organoids.

Multicellular flows are complex and can be overwhelming to study. Attractors and repellers compress this complexity into its essential units, that can be controlled and used to unravel the underlying principles driving multicellular flows."

Mattia Serra, Assistant Professor, Department of Physics, University of California