Critical Cell Spacing Drives Phase Transition in Matrix-Mediated Tissue Condensation.

Area of Science:

• Biophysics
• Tissue Engineering
• Computational Biology

Background:

• Biological tissues undergo phase transitions driven by cell-extracellular matrix (ECM) mechanical feedback.
• Understanding these transitions is crucial for tissue development and disease, such as fibrosis.

Purpose of the Study:

• To model the bio-chemo-mechanical feedback loops governing tissue phase transitions.
• To identify the physical mechanisms and critical parameters controlling cell spacing and collective tissue behavior.

Main Methods:

• Development of a bio-chemo-mechanical computational model.
• Analysis of competing physical effects of matrix stiffness on cell activation and mechanical communication.
• Validation against experimental observations across diverse cell types and collagen densities.

Main Results:

• A critical cell spacing threshold (80-160 µm) was identified, consistent with experimental data.
• The model demonstrates that matrix stiffness influences cell spacing through tension bands and mechanical percolation.
• Fibrous network architecture and its transition to strain-stiffening were shown to govern this threshold.

Conclusions:

• Fibrous architecture critically controls emergent mechanical properties in biological tissues.
• The findings provide insights into the physics of active stress in fiber-reinforced composites.
• The model suggests potential mechanical interventions for fibrotic disorders by targeting cell-matrix interactions.