Dissertations and Theses

Date of Award

2019

Document Type

Dissertation

Department

Biomedical Engineering

First Advisor

Sihong Wang

Keywords

personalized medicine, microfluidic technologies, high throughput screening, live tissue culture, computational fluid dynamics, whole tissue image analysis

Abstract

Cancer is recognized as a complex disease with both genetic and epigenetic drivers that can vary from one individual to another. While very early research into cancer treated it as a clonal malfunction that could originate from as small as a single deregulated cell, the disease itself manifests itself with several more complexities beyond tumorigenic cells only. The tumor microenvironment itself – from the extracellular matrix to stromal cells - cooperate with tumor cells in a symbiotic manner towards metastatic progression. Clinical studies have provided more information regarding the degree of individualization possible, such that patients with similar genetic makeup and cancer cell surface markers can register a dissimilar response to hormone or chemotherapy. Effective experimental drugs for an individual may be shelved from being available due to a lack of beneficial effects - or the presence of serious adverse effects that outweigh any benefits - within the majority of the population. Thus, drugs that may be effective for a small subset of the population may go underutilized. There is therefore necessity to have a platform that can screen for the most effective drug(s) on a personalized basis.

The last two decades has seen more breakthroughs towards personalized medicine, from therapy (especially immunotherapy) to establishing more realistic models ex vivo of the patient by generating patient-derived cell cultures or xenografts. A handful of companies do personalized drug testing using dissociated tumor cells from the patient’s biopsy as the basis for 2D cell culture and drug screening. Other studies try to recapitulate the best niche in 3D by formulating a matrix and media that may best suit the type of tumor cells under investigation. A few studies have progressed towards whole tissue culture experimental setups. Such studies rely on artificially formulated microenvironments after cell dissociation; or, as in the whole tissue culture, use bulky setups that interrogate single tissue pieces with very low throughput or functional viability (3-5 days).

Our focus in this work is towards the culture paradigm, using tumor biopsies from cell-derived xenografts (CDX, e.g. MB-MDA-231 and BT 474) and patient-derived xenografts (PDX, e.g. M37 and M156) breast cancer models. As this work was in progress, other labs have also worked on creating a whole tissue culture system, but employ very low-throughput systems or systems that do not keep the tissue functionally viable for more than 3-7 days. Towards this end, we develop a microfluidic tissue array (µFTA) as a platform that enables rapid seeding of multiple tumor pieces that are dissected to a size of about 0.5mm x0.5mm x1mm. The µFTA allows control of physiologically relevant flow along the tumor periphery, maintaining superior viability over 20 days against static culture conditions. The µFTA is optimized using computational models and experimental testing. It enables a platform for drug interrogation using optimal viability and proliferation assays. A valve µFTA is also implemented in this study to increase throughput. The µFTA is expected to provide a clinically relevant platform for personalized drug screening directly from biopsies, bypassing the lengthy process of PDX generation or false responses in cell cultures.

Available for download on Wednesday, December 22, 2021

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