Arrested coalescence of multicellular aggregates

Area of Science:

• Biophysics
• Materials Science
• Developmental Biology

Background:

• Multicellular aggregates display liquid-like properties, with fusion often modeled as viscous drop coalescence.
• Tissues exhibit complex viscoelastic behavior, where elastic forces can impede complete fusion, a phenomenon termed arrested coalescence.

Purpose of the Study:

• To investigate arrested coalescence in stem cell aggregates.
• To develop a theoretical framework explaining this phenomenon.
• To explore the role of active cell fluctuations in controlling phase transitions.

Main Methods:

• Experimental observation of stem cell aggregate fusion.
• Development of a theoretical framework for arrested coalescence.
• Agent-based simulations to model cell dynamics and phase transitions.
• Nanoindentation measurements to quantify mechanical properties.

Main Results:

• A theoretical framework was established that accurately models experimental observations of arrested coalescence in stem cell aggregates.
• Agent-based simulations demonstrated that active cell fluctuations can drive a solid-to-fluid phase transition, linking arrested coalescence to unjamming transitions.
• Effective viscosity, shear modulus, and surface tension of the aggregates were determined.

Conclusions:

• Arrested coalescence in stem cell aggregates is influenced by active cell fluctuations and can occur near unjamming transitions.
• The study provides a simple, rapid, and cost-effective method for characterizing the mechanical properties of viscoelastic materials.