Migration and division in cell monolayers on substrates with topological defects.

Area of Science:

• Cell biology
• Biophysics
• Materials science

Background:

• Collective cell movement is crucial for tissue development and wound healing.
• Liquid crystal order and topological defects, specifically +1 defects, are implicated in tissue morphogenesis.
• Fibroblast organization on patterned substrates requires further investigation.

Purpose of the Study:

• To investigate fibroblast organization, motion, and proliferation on substrates with micron-sized ridges that induce topological defects.
• To determine the mechanisms driving cell density variations near +1 and -1 topological defects.
• To explore the role of cell division rates versus collective migration in tissue patterning.

Main Methods:

• Simulations modeling cells as self-propelled deformable ellipses with Gay-Berne interactions.
• Experimental studies on fibroblast organization on substrates with varying ridge heights.
• Analysis of cell density, alignment, morphology, and proliferation rates near topological defects.

Main Results:

• Cell density variations near defects are primarily driven by differences in fibroblast division rates, not collective migration.
• Fibroblast alignment quality decreases at higher cell densities.
• At +1 defect centers, fibroblasts exhibit either highly anisotropic or isotropic morphologies.
• Suppressing cell migration across ridges enhances cell density at +1 defects.

Conclusions:

• Fibroblast organization and density near topological defects are regulated by proliferation rates, modulated by cell shape and area.
• Topological defects can be utilized to pattern tissues without relying on collective cell migration.
• This provides a novel mechanism for controlling tissue morphogenesis through defect engineering.