Date of Award

2017

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Graduate Group

Chemical and Biomolecular Engineering

First Advisor

Daniel A. Hammer

Abstract

Dendritic cells (DCs) are important regulators of the adaptive immune response. Integral to their antigen-presenting capability is their ability to travel from sites of antigen capture in peripheral tissues to the T cell rich zones of the lymph node. Along the way, they encounter many different environments and are presented with a variety of chemical and biophysical cues. However, the response of DC migration to these extracellular cues is not fully characterized. My first goal was to establish an in vitro culture system for studying DC chemokinesis. I chose to use PDMS surfaces due to their biocompatibility and easy functionalization. I determined that DC chemokinesis is a diffusive process modeled well by a persistent random walk. In addition, I used micropost array detectors (mPADs) to quantify the forces of chemokinesis. Next, I sought to identify biophysical and biomolecular characteristics that contribute to DC chemokinesis. Despite the diversity of microenvironments that DCs encounter, there is a paucity of information about how DCs respond to the physical characteristics of their surroundings. I addressed this question by examining differences in DC migration on surfaces with different stiffness, 2D geometry and ligand patterning. I show that DCs are insensitive to differences in substrate stiffness but are sensitive to the spatial organization of ligand. In addition, I investigated signaling pathways involved in environmental sensing. To my knowledge, this is the first investigation of DC response to substrate stiffness and geometry. Finally, I quantified random motility and force generation in HS1 -/- and WASP -/- DCs. I determined that both proteins are required for random migration, through their regulation of cellular speed. In addition, I determined that both proteins are involved in force generation. This study provides the first description of the influence of HS1 on DC random migration as well as the first measurements for traction forces from HS1 and WASP deficient DCs. In this thesis, I build upon the current knowledge of DC chemokinesis by identifying critical biophysical and biomolecular components.

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