Spatial Organization of Multicellular Living Systems
Name
Yang_hqyang_SM_MechE_SEP2022.pdf
Description
Thesis PDF
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12.35 MB
Format
Adobe PDF
Checksum (MD5)
56eec89dabdab0b0e12ab9aa400e04ac
Author(s)
Yang, Haiqian
Advisor(s)
Guo, Ming
Date Issued
September 2022
Publisher
Massachusetts Institute of Technology
Abstract
Cells cooperate as groups to achieve functions at the tissue level, and specific structural characteristics emerge from the local organization of neighboring cells. Analogous to classical physics where transformations in the local structure give rise to phases and phase transitions, the changes in local structures in multicellular assemblies can be essential for a variety of vital processes including morphogenesis, wound healing, and cancer. In this work, we use the two invariants (volume and shear) of the deformation tensor of Delaunay triangles as a pair of quantities to define the local microstates of multicellular living systems. In chapter 3, we develop configurational fingerprints based on these local structures, and extract two parameters, namely the volumetric and shear order parameters, that are reflective of the transitions of local order in the systems. Theoretically, these two parameters form a complete and unique pair of signatures for the local structural order of a multicellular system. The evolution of these two order parameters offers a robust and experimentally accessible way to map the phase transitions in expanding cell monolayers, and during embryogenesis and invasion of epithelial spheroids. In chapter 4, We show by both simulations and experiments that volume follows a k-Gamma distribution, and shear follows an exponential distribution. We further propose two temperature-like quantities for cell assemblies, in which sense we show the periphery of an extravasating epithelial monolayer is ‘hotter’ than the core.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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