Date of Award

12-2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Bioengineering

Advisor

Burg, Karen J.L.

Committee Member

LaBerge , Martine

Committee Member

Webb , Ken

Committee Member

Grimes , Lawrence

Abstract

In the United States, breast cancer is the third most common cause of cancer death (after lung cancer and colon cancer). In 2007, breast cancer is expected to cause 40,910 deaths (7% of cancer deaths; almost 2% of all deaths) in the U.S. The long term goal of this project is to develop an in vitro test system that can be used to develop breast cancer vaccine or screen breast cancer chemotherapy. This dissertation was driven by four objectives and it can be thought as a toolbox that provides practical experimental design and lab work for the development of an in vitro test system. The objectives stimulated the preliminary studies, from scaffold fabrication to the study of cancer-stromal cell interactions. Achieving Objective 1, methods of fabricating electrospun mesh and polymeric bead were introduced and the cell-material interactions were investigated. Preliminary cell studies were conducted to distinguish electrospun meshes that were made of different polymers. PLLA-based electrospun mesh showed excellent cell affinity compared with cellulose acetate mesh, the latter which is suitable for use as a tissue-repelling material. It was further found that collagen beads and PHA-PLLA beads had rougher morphologies than PLLA and PHA beads. With rougher surface textures, collagen and PHA-PLLA beads stimulated higher cellular metabolic activity than PLLA and PHA beads. In order to achieve Objective 2, a localized cell culture method was introduced and an adapted cryosectioning method was applied in order to enhance histological processes for hydrogel research. Through this localized culture method, a microenvironment that enabled the creation of intensive cell interactions was established. Mammary bovine gland epithelial cells (MAC-T) and human breast cancer cells (MCF-7) formed tubular structure and tumor-like cell masses respectively using this localized culture method. For the adapted cryosectioning method, a mixture of sucrose and O.C.T® was diffused into hydrogels and to replace the culture medium. Thus, the mechanical properties of frozen hydrogel were adjusted to fit the frozen embedding medium. In pursuit of Objective 3, a novel co-culture method was reported. This novel co-culture method can inhibit the adipogenesis of multipotent stromal cells (D1s) by simply maintaining the D1 cells in MAC-T conditioned medium; the inhibitory effect is reversible. This novel co-culture method allows us to regulate the adipogenesis of D1 cells in vitro so that the adipogenesis potential can be maintained and triggered at the optimal timing. Therefore, the inherent limitations of existing adipose tissue engineering and conventional adipose research could be eliminated. In pursuit of Objective 4, cancer-stromal cell interactions were investigated by establishing a co-culture model. The novel co-culture method, developed in pursuit of Objective 3, was applied in pursuit of Objective 5 in order to regulate the differentiation of multipotent stromal cells and influence the behavior of breast cancer cells.

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