Abstract

Epithelial cells form complex and dynamic tissue structures within the human body. During these processes, cells must come in contact with a variety of dissimilar cell types, extracellular matrix (ECM) proteins, and mechanical changes not aligned with homeostasis. In this thesis, we explore how changes to the surrounding environment can impact mechanoresponse of epithelial cells. We developed an in vitro system by using elastically tunable polyacrylamide substrates with collagen coating to understand how mechanics can affect collective cell migration. In the first aim, we added macrophages chemically polarized as M0, M1, or M2-like macrophages co-cultured with epithelial cells. We found that M0 and M1-like macrophages caused epithelial cells to cluster. These clusters were formed through an increase in contractility and a reduction of cell-ECM adhesions. When co-cultured with M2-like macrophages, epithelial cells maintained cohesive sheet-like structures and migrated along the substrate. This clustering phenotype arose because of macrophage-dependent cytokine secretion, competition between cell-cell and cell-ECM adhesions and increased epithelial cell contractility in the presence of M0 and M1-like macrophages. In the second aim, we sought to understand how microscale disruptions in heterogenous ECMs affect collective epithelial cell migration. Using a similar hydrogel set-up as the first aim, we used the elastically tunable polyacrylamide gels to coat either Collagen type-I or Collagen type-IV to the surface. When we generated microscale defects to the surface, cells on Collagen type-IV coatings collapsed into the superficial defect. The superficial defect caused a stalling in collective cell migration and multicellular collapse of the actin architecture. When we compared this to Collagen type-I coatings, we found that cells were able to migrate over the superficial microscale defect. Because Collagen type-I is more fibrillar compared to Collagen type-IV, cells were able to form longer filopodia to reach over the defect. Through both aims, we found mechanical tuning through cell stiffness, substrate stiffness, and membrane tension can change cellular response to immune cells and microscale defects. This work contributes to the growing understanding of the mechanisms that govern collective cell migration in response to microscale changes to the environment, both biomechanical and biochemical.

Committee Chair

Amit Pathak

Committee Members

Amber Stratman; Lori Setton; Matthew Bersi; Tony Tsai

Degree

Doctor of Philosophy (PhD)

Author's Department

Biomedical Engineering

Author's School

McKelvey School of Engineering

Document Type

Dissertation

Date of Award

11-10-2025

Language

English (en)

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