Date of Award

12-14-2015

Document Type

Open Access Thesis

Department

Biomedical Engineering

First Advisor

Esmaiel Jabbari

Abstract

Metastasis, resistance to chemo- and radiotherapy, and eventual relapse has been attributed to a tumor subpopulation known as cancer stem cells (CSCs). CSCs are regulated in their tumor microenvironment by various factors. Synthetic hydrogels can be used to investigate the effects of individual environmental factors on CSCs by providing inert 3D matrices. In this thesis, poly ethylene glycol diacrylate (PEGDA) hydrogel with 5kpa modulus has been used as a culture system to study the effect of; I) integrin and heparin binding peptides, 2) pH, and 3) the shape of the microenvironment on breast CSCs maintenance and tumorsphere formation in PEGDA. Human breast cancer cells were encapsulated in PEGDA hydrogels and the effect of the peptides, pH, and the shape of the environment on tumorsphere formation was investigated by fluorescent microscopy, qRT-PCR and DNA content assay. All peptides including RGD, RYD, IKLLI, LIGRKK, VAPG, WQPPRARI, and SPPRRARV affected breast cancer cells by reducing their capability of sphere formation. Among peptides, RGD, RYD, and WQPPRARI were the most effective peptides in reducing sphere formation of breast CSCs. Moreover, different shapes of micropatterned PEGDA including circle, square, and rectangle did not influence CSCs maintenance and behavior in forming tumorsphere. Breast CSCs formed spherical tumors regardless of the shape of the micropatterned PEGDA and had the minimum surface area for a given volume. Furthermore, breast CSCs showed more resistance to acidic pH compared to non-stem breast cancer cells and normal breast epithelial cells.

Rights

© 2015, Leily Daneshian

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