Degree

Doctor of Philosophy (PhD)

Department

Cain Department of Chemical Engineering

Document Type

Dissertation

Abstract

Metastatic breast cancer significantly decreases patient survival, with the majority of deaths caused by secondary metastasis. Cancer metastasis is a multi-step process that starts with the detachment of a cancer cell from the primary tumor and ends with establishing a secondary tumor at a distal location. This work's focus was to use an interdisciplinary microscale approach to study how cancer cells respond to neighboring cells and how they migrate in response to chemical gradients. Two distinct devices, a microfluidic device, and a 3D-printed plate insert, were developed to perform co-culture studies to elucidate the impact of ASCs on cancer cell growth, proliferation, morphology, and drug resistance. Biophysical studies using the microfluidic device established that ASCs promoted triple-negative breast cancer cells (MDA-MB-231) to adopt a more aggressive morphology and increased drug resistance. The 3D-printed insert was developed to be compatible with either a 10 cm petri dish (to harvest for post-experimental molecular analysis) or a 6-well plate (to quantify cell growth). The insert incorporated an agarose hydrogel to create two distinct culture regions that were physically separated yet chemically connected, facilitating the mass transfer of biomolecules. Control experiments resulted that there was no difference in cellular morphology, cellular growth, or cellular viability between the plate insert and controls results, while co-culture experiments of 231 and ASCs confirmed the ability of the insert to co-culture. The third aspect of this thesis focused on the directed migration of cancer cells to soluble chemical cues, also known as chemotaxis. Several approaches have been developed to study the tactic movement of cancer cells in two-dimensional (2D) environments; however, these studies cannot recapitulate the spatial and temporal cues encountered by cells in three-dimensional (3D) environments. A three-channel microfluidic device was designed to generate a time-resolved oscillating gradient of chemoattractants to study how cancer cells can break the spatial limitation currently associated with the chemotactic response. The device allowed for creating the oscillating gradient of extracellular chemicals to switch between ‘on’ and ‘off’ positions. The results demonstrated that the chemotactic memory of 231 cells was regenerated by responding to the oscillating gradient of 20% FBS when the gradient was re-created after erasing in the middle of the experiment. This thesis presented microscale approaches that allow experiments to study cellular interactions and long-range chemotaxis of cancer cells in the tumor microenvironment, contributing to understanding the cancer treatment.

Date

1-13-2021

Committee Chair

Melvin, Adam T.

Available for download on Sunday, March 20, 2022

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