title: Separation and detection of rare cells in a microfluidic disk via negative selection.
abstract: Cyto-analysis of rare cells often requires separation and detection with each procedure posing substantial challenges. This paper presents a disk-based microfluidic platform for both procedures via an immunomagnetic negative selection process. The microfluidic platform's unique features include a multistage magnetic gradient to trap labeled cells in double trapping areas, drainage of fluid to substantially shorten detection time, and a bin-like regions to capture target cells to facilitate a seamless enumeration process. Proof-of-concept was conducted using MCF7 as target rare cells (stained with anti-cytokeratin-FITC antibodies) spiked into Jurkat Clone E6-1 non-target cells (labeled with anti-CD45-PE and anti-PE BD magnetic beads). Then, mononuclear cells (MNC) from healthy blood donors were mixed with MCF7s, modeling rare cells, and tested in the disk. Results show a non-linear magnetic coupling effect of the multistage magnet substantially increased the trapping efficacy over that of a single magnet, contributing to the depletion rate of Jurkats, which reaches 99.96%. Detection time is extensively shortened by depletion of 95% of non-cell-containing fluid in the collection area. The average yield of detected MCF7 cells is near-constant 60 ± 10% over a wide range of rarity from 10(-3) to 10(-6) and this yield also holds for the MCF7/MNC complex mixture. Comparison with autoMACS and BD IMagnet separators revealed the average yield from the disk (60%) is superior to that of autoMACS (37.3%) and BD IMagnet (48.3%). The advantages of near-constant yield, roughly 30 min of operation, an acceptable level of cell loss, and potentially low cost system should aid in cyto-analysis of rare cells.
authors.affiliation: Institute of Applied Mechanics, National Taiwan University, Taipei, Taiwan.
authors.forename: Chen-Lin
authors.initials: CL
authors.lastname: Chen
authors.forename: Ken-Chao
authors.initials: KC
authors.lastname: Chen
authors.forename: Yu-Cheng
authors.initials: YC
authors.lastname: Pan
authors.forename: Tai-Ping
authors.initials: TP
authors.lastname: Lee
authors.forename: Lo-Chang
authors.initials: LC
authors.lastname: Hsiung
authors.forename: Cheng-Ming
authors.initials: CM
authors.lastname: Lin
authors.forename: Chang-Yu
authors.initials: CY
authors.lastname: Chen
authors.forename: Ching-Hung
authors.initials: CH
authors.lastname: Lin
authors.forename: Bor-Luen
authors.initials: BL
authors.lastname: Chiang
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Wo
mesh_terms: D000911:Antibodies, Monoclonal; D045744:Cell Line, Tumor; D006801:Humans; D018189:Immunomagnetic Separation / Q000379:methods*; D019169:Jurkat Cells; D007633:Keratins / Q000032:analysis; D017493:Leukocyte Common Antigens / Q000032:analysis; D007962:Leukocytes; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods*
chemical_list: D000911:Antibodies, Monoclonal; D007633:Keratins; D017493:Leukocyte Common Antigens