Nematic characterization of a confluent monolayer of mouse liver fibroblasts

Abstract

In biophysics, modeling tissues as active nematic liquid crystals provides a powerful framework to understand the collective organization of spindle-shaped cells. Here, the topological nature of mouse liver fibroblast monolayers is investigated. A custom computational pipeline was developed to extract local orientation fields and compute the tensor-averaged geometry of +1/2 comet defects from experimental datasets. These geometries, alongside a theoretically ideal defect, governed by the one-constant approximation (K1 = K3), were physically replicated onto glass substrates using PRIMO micropatterning. When seeded onto these engineered patterns, fibroblast populations successfully remained spatially confined for 120 hours. However, internal cellular alignment dynamically evolved, developing emergent defects, and undergoing a full or partial −π/2 (counterclockwise) rotation. The mathematically ideal pattern better accommodated this late-stage nematic organization. This work establishes a comprehensive methodology to mathematically model and physically engineer nematic designs, enabling the reproducibility of active nematic based experiments.