Crisscross multilayering of cell sheets

Trinish Sarkar, Victor Yashunsky, Louis Brézin, Carles Blanch Mercader, Thibault Aryaksama, Mathilde Lacroix, Thomas Risler, Jean-François Joanny, Pascal Silberzan

Research output: Contribution to journalArticlepeer-review


Hydrostatic skeletons such as the Hydra's consist of two stacked layers of muscle cells perpendicularly oriented. In vivo, these bilayers first assemble, and then the muscle fibers of both layers develop and organize with this crisscross orientation. In the present work, we identify an alternative mechanism of crisscross bilayering of myoblasts in vitro, which results from the prior local organization of these active cells in the initial monolayer. The myoblast sheet can be described as a contractile active nematic in which, as expected, most of the +1/2 topological defects associated with this nematic order self-propel. However, as a result of the production of extracellular matrix (ECM) by the cells, a subpopulation of these comet-like defects does not show any self-propulsion. Perpendicular bilayering occurs at these stationary defects. Cells located at the head of these defects converge toward their core where they accumulate until they start migrating on top of the tail of the first layer, while the tail cells migrate in the opposite direction under the head. Since the cells keep their initial orientations, the two stacked layers end up perpendicularly oriented. This concerted process leading to a crisscross bilayering is mediated by the secretion of ECM.
Original languageEnglish
Article numberpgad034
Pages (from-to)1-11
JournalPNAS nexus
Issue number3
StatePublished - 3 Feb 2023


  • Collective behaviors
  • Collective cellular migration
  • Nematics
  • Active matter
  • Active nematics
  • Multilayer

ASJC Scopus subject areas

  • Physics and Astronomy (all)
  • General Biochemistry, Genetics and Molecular Biology


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