Abstract 1593: Label-free high throughput microfluidic device for the isolation of circulating tumor cells from breast cancer patients
Authors: Lin Eric , Rivera Lianette , Yoon Hyeun Joong , Fouladdel Shamileh , Wieger Jacob , Guthrie Stephanie , Deol Yadwinder S. , Clouthier Shawn G. , Luther Tahra K. , Simeone Diane M. , Burness Monika L. , Azizi Ebrahim , Wicha Max S. , Nagrath Sunitha 
Published: August 2015

Abstract
Introduction and Objective: A necessary step in distant metastasis is the hematogenous dissemination of cancer cells from the primary tumor site to remote sites. The presence of circulating tumor cells (CTCs) in the peripheral blood represents a strong and independent prognostic factor for decreased disease-free and overall survival in many solid malignancies. Immune-affinity based capture is the most commonly used method for the isolation of CTCs which utilizes antibodies to capture tumor cells expressing specific proteins. However, immune-affinity based approaches offer low throughput (∼1mL/hr) and considerable cell loss (∼20-40%) resulting from heterogeneous expression of biomarkers on CTCs. Various label-free approaches utilizing physical properties of CTCs have been developed to overcome the limitations of immune-affinity based isolation techniques, including micro-filters, microscale laminar vortices, inertial migration of particles, and integrated systems. Here we present an inertial microfluidic-based separation technique for high throughput and label-free isolation of CTCs that yields the highest throughput with high CTC recovery and high blood cell removal among all the label-free technologies.
Methods: The PDMS-made microfluidic device has 637 mm in length with 56 corners, 500 μm in width, and 100 μm in height. The separation is driven by two main forces: (i) inertial force that focuses the cells into streamlines, and (ii) drag force from Dean flow that migrates the focused cells to various positions based on size. The device was optimized with MCF-7 and Panc-1 cell lines spiked into PBS buffer and also diluted blood. It was then tested on 10 mL blood samples from patients with metastatic breast cancer. The separated cells were cytospun and stained to identify CTCs as cytokeratin positive, DAPI positive, CD45 negative cells.
Results: Samples were processed through the inertial microfluidic device that enriches CTCs in the second outlet based on size difference between CTCs and blood cells. The device was optimized to operate at an extremely high throughput of 2500 μL/min with high recovery (92% for both spiked samples of MCF-7 and PANC-1 cell lines) and high white blood cells (WBCs) removal (91%). To determine the efficiency of capture of rare cell populations, healthy donor blood samples were spiked with MCF-7/GFP at 100 cells and 95% recovery was obtained. In patient samples, we identified CTCs in 24 of 27 (89%) breast patients with metastatic disease (4.3±4.8 CTCs/mL) with low WBCs contamination (465±473 WBCs/mL).
Conclusion: The study of CTCs could have a direct impact upon patient care by presenting a novel CTC isolation method. This technology may be applicable to early detection, and also for monitoring response to treatment. Our approach is superior to current strategies because it is independent of cell surface markers, which may be varied in tumor cells, and may exclude cancer stem cells.
Citation Format: Eric Lin, Lianette Rivera, Hyeun Joong Yoon, Shamileh Fouladdel, Jacob Wieger, Stephanie Guthrie, Yadwinder S. Deol, Shawn G. Clouthier, Tahra K. Luther, Diane M. Simeone, Monika L. Burness, Ebrahim Azizi, Max S. Wicha, Sunitha Nagrath. Label-free high throughput microfluidic device for the isolation of circulating tumor cells from breast cancer patients. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1593. doi:10.1158/1538-7445.AM2015-1593