Continuous Flow Deformability‐Based Separation of Circulating Tumor Cells Using Microfluidic Ratchets

Abstract

Circulating tumor cells (CTCs) offer tremendous potential for the detection and characterization of cancer. A key challenge for their isolation and subsequent analysis is the extreme rarity of these cells in circulation. Here, a novel label-free method is described to enrich viable CTCs directly from whole blood based on their distinct deformability relative to hematological cells. This mechanism leverages the deformation of single cells through tapered micrometer scale constrictions using oscillatory flow in order to generate a ratcheting effect that produces distinct flow paths for CTCs, leukocytes, and erythrocytes. A label-free separation of circulating tumor cells from whole blood is demonstrated, where target cells can be separated from background cells based on deformability despite their nearly identical size. In doping experiments, this microfluidic device is able to capture >90% of cancer cells from unprocessed whole blood to achieve 10(4) -fold enrichment of target cells relative to leukocytes. In patients with metastatic castration-resistant prostate cancer, where CTCs are not significantly larger than leukocytes, CTCs can be captured based on deformability at 25× greater yield than with the conventional CellSearch system. Finally, the CTCs separated using this approach are collected in suspension and are available for downstream molecular characterization.

Deformability based Cell Sorting using Microfluidic Ratchets Enabling Phenotypic Separation of Leukocytes Directly from Whole Blood

“…However, we also recognize there are many applications where greater throughput is desired. In these situations, throughput can be increased by parallelizing the mechanism, as well as optimizing the device design for the specific application, as we have done for a device to enrich for circulating tumor cells, which has a sample throughput of 1 ml/hour 36 .…”

“…Building on results from cell deformability studies performed using AFM 32 , micropipette aspiration 33, 34 and its microfluidic derivative 35 , we hypothesize that erythrocytes, leukocytes and leukocyte subpopulations can be sensitively separated based on their distinct cell deformability. Previously, the microfluidic ratchet mechanism has been shown to be able to effectively separate viable circulating tumor cells from whole blood 36 with significant improvements in yield over conventional methods as well as to separate erythrocytes infected with Plasmodium falciparum 37 from uninfected erythrocytes to improve the sensitivity of malaria diagnosis. Using oscillating flow of cells through an array of funnel shaped microstructures, we show that whole blood can be processed without clogging or fouling the filter matrix.…”

The Potential for Circulating Tumor Cells in Pancreatic Cancer Management

“…Cancer cells are known to be more deformable than normal cells, a quality that is correlated to their metastatic potential and is exploited by some enrichment platforms (Byun et al, 2013; Park et al, 2016). Additionally, platforms utilizing tumor cell property differences in electrical charge and density have been reported (Müller et al, 2005; Fabbri et al, 2013; Yoo et al, 2016).…”

Microfluidics in the selection of affinity reagents for the detection of cancer: paving a way towards future diagnostics

“…Furthermore, a micro cell culture module for E. coli was used to facilitate the amplification of bound phages. 91,[99][100][101][102] Therefore, it is envisioned that more cancer biomarkers will be identified with these microfluidic systems in the coming years. This chip has been further used to identify affinity probes for colon cancer cells.…”