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SUMMARY:Making the cornea spiral: Constructing quantitative simulations of
  epithelial cell sheets - Silke Henkes\, Leiden University
DTSTART:20230228T130000Z
DTEND:20230228T140000Z
UID:TALK196366@talks.cam.ac.uk
CONTACT:Tal Agranov
DESCRIPTION:Epithelial cell sheets perform major biological functions by s
 haping the developing embryo\, and they are equally important as barrier t
 issue in the adult\, such as in the gut\, or in the case of the corneal ep
 ithelium\, the surface of the eye. This tissue consists of a thin layer of
  cells on a spherical cap\, where cells are born at the edges (the limbus)
  and then migrate\, divide\, and are extruded in a steady-state spiral mig
 ration pattern with a vortex at the centre. \nIn this talk\, I will presen
 t a quantitative soft active matter model of this process. In a minimal ap
 proach\, we model each cell as an active Brownian particle with a crawling
  speed\, short-range interactions\, orientational diffusion and alignment 
 with other particles\, as well as density-feedback division and death. \nF
 irst\, we consider in in-vitro corneal cell sheets\, where we identify a c
 haracteristic correlated velocity pattern that emerges from uncorrelated a
 ctive persistent motion\, a very general active effect. \nUsing the fully 
 fitted model to these in-vitro cells as well as corneal explants\, we are 
 able to simulate a full\, spiralling cornea. The central spiral emerges as
  a +1 topological defect of the director and velocity fields\, and is only
  present if the system crosses the flocking threshold in polar alignment. 
 Thus we are able to identify the system as belonging to the class of polar
  systems without density conservation\, and write a flux conservation equa
 tion for the spiral angle.\nWe match the simulations with data obtained fr
 om tracing the stripes of dissected mouse eyes\, from which we can infer t
 he velocity field. We obtain good quantitative agreement on spiral angle\,
  and renewal time of the tissue.
LOCATION:Center for Mathematical Sciences\, Lecture room MR4\, or https://
 maths-cam-ac-uk.zoom.us/j/98016675669
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