Topological defects patterns in monolayers of cells

Many cell types possess long-range orientational order [1], responsible for influencing cell-cell communication and patterns of cell migration. It is therefore possible to consider ensembles of cells in analogy with nematic liquid crystals (NLCs). In particular, monolayers of spindle-like cells show almost perfect NLC behavior [2]. As liquid crystals, cells also form topological defects, which can be classified on the basis of their topological charge. These are either formed spontaneously in cell monolayers, or induced by controlled boundary conditions [3, 4].
We create topographical patters with micro-ridges to align cells and impose distortions and topological defects [5]. We can thus analyze the alignment of cells in the vicinity of the topological defects under different conditions and observe multiple possible solutions that the cells utilize to adapt to the boundaries. We compare the alignment of various cell types with the micro-ridges and the organization of the monolayers on the patterns. The geometry of the micro-ridges allows us to vary the degree of confinement of the cells, so that we can establish an analogy between this and the anchoring strength in NLCs.

[1] X. Li et al., Proc. Natl. Acad. Sci. 114, 8974-8979 (2017)
[2], G. Duclos et al., Soft Matter 10, 2346–2353 (2014)
[3] G. Duclos et al., Nat. Phys. 13, 58–62 (2017)
[4] T. Turiv et al., Sci. Adv. 6, eaaz6485 (2020)
[5] K. Endresen et al., arXiv:1912.03271 (2020)