Browsing by Author "Basan, Markus"

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    Alignment of cellular motility forces with tissue flow as a mechanism for efficient wound healing
    (National Academy of Science, 2012) Basan, Markus; Elgeti, Jens; Hannezo, Edouard; Rappel, Wouter-Jan; Levine, Herbert; Center for Theoretical Biological Physics; Bioengineering; Center for Theoretical Biological Physics
    Recent experiments have shown that spreading epithelial sheets exhibit a long-range coordination of motility forces that leads to a buildup of tension in the tissue, which may enhance cell division and the speed of wound healing. Furthermore, the edges of these epithelial sheets commonly show finger-like protrusions whereas the bulk often displays spontaneous swirls of motile cells. To explain these experimental observations, we propose a simple flocking-type mechanism, in which cells tend to align their motility forceswith their velocity. Implementing this idea in amechanical tissue simulation, the proposed model gives rise to efficient spreading and can explain the experimentally observed long-range alignment of motility forces in highly disordered patterns, as well as the buildup of tensile stress throughout the tissue. Our model also qualitatively reproduces the dependence of swirl size and swirl velocity on cell density reported in experiments and exhibits an undulation instability at the edge of the spreading tissue commonly observed in vivo. Finally, we study the dependence of colony spreading speed on important physical and biological parameters and derive simple scaling relations that show that coordination of motility forces leads to an improvement of the wound healing process for realistic tissue parameters.
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    Intercellular Stress Reconstitution from Traction Force Data
    (Elsevier, 2014) Zimmermann, Juliane; Hayes, Ryan L.; Basan, Markus; Onuchic, José N.; Rappel, Wouter-Jan; Levine, Herbert; Center for Theoretical Biological Physics
    Cells migrate collectively during development, wound healing, and cancer metastasis. Recently, a method has been developed to recover intercellular stress in monolayers from measured traction forces upon the substrate. To calculate stress maps in two dimensions, the cell sheet was assumed to behave like an elastic material, and it remains unclear to what extent this assumption is valid. In this study, we simulate our recently developed model for collective cell migration, and compute intercellular stress maps using the method employed in the experiments. We also compute these maps using a method that does not depend on the traction forces or material properties. The two independently obtained stress patterns agree well for the parameters we have probed and provide a verification of the validity of the experimental method.