CONTINUOUS FLOW CTC CELL LABELLING USING MICROFLUIDIC FLOW FOLDING TECHNIQUES
Nabid Ahmed1, Colin Hisey2, Derek Hansford2.
1Ohio State University Medical Center, Columbus, OH, 2Ohio State University, Columbus, OH.
The study of circulating tumor cells (CTCs) from low volumes of patient blood can provide information on primary tumor characteristics, response to certain treatments, and mean survival time. This diagnostic tool requires separation of CTCs from other blood components and is based on manipulating the unique characteristics of CTCs (size, surface protein expression etc.). Cellsearch, the only FDA-approved CTC isolation device, is limited in that its function is only semi-automated, and the isolated CTCs are not viable after processing, making secondary analysis difficult. Microfluidic devices with functional requirements of high isolation purity, high separation efficiency, and high throughput processing are currently being developed to effectively isolate CTCs from blood. Microfluidic designs can either operate under passive and/or active mixing principles. Active mixers use external energy (i.e., electrical) to mix fluid flows, while passive mixers require no energy input and rely on channel geometry. Our passive mixing device is made using soft lithographic techniques and offers continuous on-chip labelling of CTCs with antibody-functionalized beads using various embedded groove flow-folding designs. This study characterizes the labeling efficiency of these grooved microchannels by combining separate streams of calcein-stained MCF7 cells and anti-EpCAM coated fluorescent microbeads in the flow. Video analysis using fluorescence microscopy allows for optimizing the groove pattern, height, and location within the microchannel in addition to flow rates. Future work entails using these optimized devices to label the CTCs with magnetic beads and manipulate the labeled cells using a magnetic tweezer/permalloy disk array to make downstream analysis possible.