Topological defects control collective dynamics in neural progenitor cell cultures

Area of Science:

• Biophysics
• Developmental Biology
• Regenerative Medicine

Background:

• Characterizing cultured stem cell morphology and collective patterns is largely qualitative.
• Neural progenitor cells (NPCs) are multipotent stem cells crucial for central nervous system development.

Purpose of the Study:

• To quantitatively analyze the collective dynamics and emergent patterns of cultured murine NPCs.
• To investigate the role of topological defects in NPC behavior and tissue formation.

Main Methods:

• Observation of NPC cultures at varying densities.
• High-resolution imaging to capture single-cell dynamics.
• Analysis of cell alignment, velocity fields, and density patterns.
• Quantification of topological defects (+1/2 and -1/2).

Main Results:

• At high densities, NPCs align and move collectively, forming liquid-crystalline patterns.
• Topological defects (+1/2 and -1/2) were identified within the cell alignment.
• +1/2 defects promoted rapid cell accumulation and 3D mound formation.
• -1/2 defects facilitated cell escape, influencing density patterns.

Conclusions:

• NPC collective dynamics exhibit liquid-crystalline order with emergent topological defects.
• Topological defects act as organizers of cell density, driving tissue morphogenesis.
• A generic mechanism involving anisotropic friction and active forces explains density instabilities around defects.