Cite this: DOI: 10.1039/c3lc50617g Slanted spiral microfluidics for the ultra-fast, label-free isolation of circulating tumor cells3 Received 19th May 2013, Accepted 3rd July 2013 DOI: 10.1039/c3lc50617g www.rsc.org/loc Majid Ebrahimi Warkiani,{ a Guofeng Guan,{,§ ab Khoo Bee Luan,{ c Wong Cheng Lee, a Ali Asgar S. Bhagat, d Parthiv Kant Chaudhuri, c Daniel Shao-Weng Tan, e Wan Teck Lim, e Soo Chin Lee, f Peter C. Y. Chen, ab Chwee Teck Lim* abcg and Jongyoon Han* ah The enumeration and characterization of circulating tumor cells (CTCs), found in the peripheral blood of cancer patients, provide a potentially accessible source for cancer diagnosis and prognosis. This work reports on a novel spiral microfluidic device with a trapezoidal cross-section for ultra-fast, label-free enrichment of CTCs from clinically relevant blood volumes. The technique utilizes the inherent Dean vortex flows present in curvilinear microchannels under continuous flow, along with inertial lift forces which focus larger CTCs against the inner wall. Using a trapezoidal cross-section as opposed to a traditional rectangular cross-section, the position of the Dean vortex core can be altered to achieve separation. Smaller hematologic components are trapped in the Dean vortices skewed towards the outer channel walls and eventually removed at the outer outlet, while the larger CTCs equilibrate near the inner channel wall and are collected from the inner outlet. By using a single spiral microchannel with one inlet and two outlets, we have successfully isolated and recovered more than 80% of the tested cancer cell line cells (MCF-7, T24 and MDA-MB-231) spiked in 7.5mL of blood within 8 min with extremely high purity (400– 680 WBCs mL 21 ; y4 log depletion of WBCs). Putative CTCs were detected and isolated from 100% of the patient samples (n = 10) with advanced stage metastatic breast and lung cancer using standard biomarkers (CK, CD45 and DAPI) with the frequencies ranging from 3–125 CTCs mL 21 . We expect this simple and elegant approach can surmount the shortcomings of traditional affinity-based CTC isolation techniques as well as enable fundamental studies on CTCs to guide treatment and enhance patient care. Introduction Circulating tumor cells (CTCs) are rare cancer cells found in the blood of metastatic cancer patients that potentially provide a convenient source for the detection, characterization and monitoring of non-hematologic cancers. 1 They have been shown to resemble the primary tumor, carry similar genetic information and can thus act as surrogates for obtaining primary material from the initial tumor for monitoring of the tumor phenotype/genotype. 2,3 Besides its prognostic signifi- cance, CTC enumeration can also be used to assess the efficacy of therapeutic treatment. 4 The ability to isolate and enrich a large number of intact CTCs for analysis and characterization is pivotal to elucidating the mechanisms underlying the metastatic process. 5 Additionally, the enrichment and culture of viable CTCs from blood of cancer patients will provide immense opportunities for the development of new anti- cancer drugs for future targeted therapies. 6,7 However, the extremely low number of CTCs in the blood makes enumera- tion and characterization a huge technical challenge. 8 Therefore, high enrichment yield and high detection accuracy are essential to maximize both assay sensitivity and reprodu- cibility. Many current CTC enrichment techniques primarily involve affinity-based detection using antibodies against epithelial cell surface markers (e.g., EpCAM). For instance, the only US FDA- approved CTC diagnostic system, CellSearch1 by Veridex LLC, is one such technique using epithelial antibodies conjugated to magnetic beads to enrich tumor cells from blood. Similar a BioSystems and Micromechanics (BioSyM) IRG, Singapore-MIT Alliance for Research and Technology (SMART) Centre, Singapore. E-mail: jyhan@mit.edu; ctlim@nus.edu.sg b Department of Mechanical Engineering, National University of Singapore, Singapore c Mechanobiology Institute, National University of Singapore, Singapore d Clearbridge BioMedics Pte Ltd, Singapore e Department of Medical Oncology, National Cancer Centre Singapore, Singapore f Departments of Hematology-Oncology and Pharmacology, National University Hospital, Singapore g Department of Bioengineering, National University of Singapore, Singapore h Department of Electrical Engineering and Computer Science, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA 3 Electronic supplementary information (ESI) available. See DOI: 10.1039/ c3lc50617g { Authors contributed equally. § Current address: Clearbridge BioMedics Pte Ltd, Singapore. Lab on a Chip PAPER This journal is ß The Royal Society of Chemistry 2013 Lab Chip Published on 03 July 2013. Downloaded on 27/08/2013 04:02:31. View Article Online View Journal