Cells Incognito: Microfluidic Tools for Detecting and Isolating Cancer Cells

Abstract

Cancer continues to be one of the leading causes of death around the world. The disease is characterized by uncontrolled cell growth and is spread throughout the body by the dissemination of cancer cells into circulation. These cells contain the mutations that caused the original tumor and can seed metastases in distant sites. Most cancer deaths result from metastasis and preventing this is vital to developing an effective cure. Detecting and isolating the cells that spread disease can facilitate this by making these cells accessible to researchers. Heterogeneity among cancer cells necessitates the study of single cells. This heterogeneity is thought to be critical to progress in cancer treatment, since a subset of cells can evade detection and seed new metastases after the original cancer has been treated. While there has been a lot of work done to understand these dangerous and elusive cells, new tools are needed to accurately isolate them from large cell populations. Microfluidic devices move detection to the microscale, allowing for precise detection and manipulation of individual cells. In this thesis, work is presented on microfluidic devices to detect, isolate and manipulate cancer cells. There are three main projects discussed. The first is improved detection of the subpopulation of circulating tumor cells (CTCs) thought to be most likely to seed new tumors. These cells express low levels of epithelial markers after undergoing a physiological change, the epithelial-to-mesenchymal transition, which allows them to better survive in circulation. Detection is done on our in-house CTC isolation platform, ensemble decision aliquot ranking (eDAR). Next, a novel electrochemical cell trapping platform for isolation of single cells for analysis is discussed. This device utilizes bi-polar electrodes (BPEs) to create faradaic ionic enrichment (FIE) or depletion (FID) zones to manipulate cells. Finally, a microfluidic device for the isolation of circulating tumor cells is presented. This device is based on eDAR, but implements a sequential sorting scheme to improve purity (1% to 70%) and isolate the cells in a 96-well plate for downstream analysis.