| Summary: | Circulating tumour cells (CTCs) are cancer cells shed from a primary tumour site into the bloodstream, where they have the potential to invade other tissues in the body, and thus become the seed of metastases. CTCs have great potential to monitor disease progression and guide cancer treatment, but a key technical challenge for their isolation and characterization is their extreme rarity in blood. CTCs are commonly enriched using immunoaffinity, which while being highly selective, may fail to capture cells that have weak antigen expression. The biophysical properties of CTCs offer a compelling alternative to immunoenrichment. CTCs are much larger in size than erythrocytes, but are similar to leukocytes. Owing to their epithelial origin however, CTCs are likely to be more rigid than leukocytes which allows for deformability based methods to separate these cells. Previously, our group has demonstrated the continuous flow microfluidic ratchet device for deformability based separation of CTCs. Here, an improved version of the device has been developed to be compatible with pre-enrichment methods, allowing for a dramatic increase in throughput. While similar in principle to the previous version, this work specifically improves the design of the sample infusion area to increase the points of contact between the sorting matrix and sample inlet, in order to prevent the accumulation of cell debris. Using this new design, epoxy resin devices and supporting instrumentation were developed to provide a pathway towards scale-up production and automation. These combined improvements allow biology laboratory technicians to enrich CTCs without significant training. The improved device is capable of capturing > 80% CTCs from whole blood at a throughput of 1 mL/hr, which when combined with a red blood cell lysis pre-enrichment step, increases to 8 mL/hr. Finally, devices were used to enrich CTCs from patients with metastatic castration-resistant prostate cancer. CTCs were found in 3 out of 11 patients, with an average count of 78. The enriched cells were further processed to perform single cell genomic sequencing where CTCs were found to contain driver mutations including those commonly associated with prostate cancer. === Applied Science, Faculty of === Mechanical Engineering, Department of === Graduate
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