Spatiotemporal Oscillation in Confined Epithelial Motion upon Fluid-to-Solid Transition

Area of Science:

• Cellular and Tissue Mechanics
• Developmental Biology
• Biophysics

Background:

• Fluid-to-solid phase transitions are vital in multicellular development (e.g., embryogenesis, morphogenesis).
• Biomechanical studies on these transitions are limited, with unknown regulatory factors and cell behavior mechanisms.
• Cellular behavior varies with tissue stress and confinement.

Purpose of the Study:

• To investigate fluid-to-solid phase transitions in geometrically confined multicellular assemblies.
• To identify factors governing these transitions and their impact on cell behavior.
• To elucidate the role of confinement size in regulating cellular mechanics and tissue morphogenesis.

Main Methods:

• Utilized geometrically confined Madin-Darby canine kidney (MDCK) cell monolayers.
• Observed spatiotemporally oscillatory motions dependent on confinement size and periphery distance.
• Performed nanomechanical mapping to assess epithelial tensional stress and substrate traction forces.

Main Results:

• MDCK monolayers exhibited confinement size-dependent oscillatory motions.
• Epithelial tensional stress and traction forces correlated with confinement size.
• Oscillation patterns and nanomechanics were linked to stress fiber assembly and cell polarization.

Conclusions:

• Confinement size-dependent surface tension regulates actin fiber assembly, cellular force generation, and cell polarization.
• A characteristic confinement size was identified that triggers the fluid-to-solid transition.
• Findings offer insights into geometrical and nanomechanical control of tissue morphogenesis and growth.