Integration of Lateral Filter Arrays with Immunoaffinity for Circulating‐Tumor‐Cell Isolation

Abstract

Circulating tumor cells (CTCs) are an important biomarker for cancer prognosis and treatment monitoring. However, the heterogeneity of the physical and biological properties of CTCs limits the efficiency of various approaches used to isolate small numbers of CTCs from billions of normal blood cells. To address this challenge, we developed a lateral filter array microfluidic (LFAM) device to integrate size‐based separation with immunoaffinity‐based CTC isolation. The LFAM device consists of a serpentine main channel, through which most of a sample passes, and an array of lateral filters for CTC isolation. The unique device design produces a two‐dimensional flow, which reduces nonspecific, geometric capture of normal cells as typically observed in vertical filters. The LFAM device was further functionalized by immobilizing antibodies that are specific to the target cells. The resulting devices captured pancreatic cancer cells spiked in blood samples with (98.7±1.2) % efficiency and were used to isolate CTCs from patients with metastatic colorectal cancer.

Incorporation of lateral microfiltration with immunoaffinity for enhancing the capture efficiency of rare cells

“…There are significant differences between this LFAM2 device and our previous reported LFAM device 32 . The filter size in LFAM is 10-6 µm whereas that in LFAM2 is 24-12 µm.…”

“…In other words, the bond force experienced by a cell is much bigger than the hydrodynamic force it faces, thus the LFAM2 device is capable of capturing CTCs by immunoaffinity. Note that the hydrodynamic force experienced by a cell in LFAM2 (up to 8.9 nN) is significantly smaller than the same force in previously reported LFAM 32 (up to 21.3 nN). Since the viability of cells captured in LFAM was 83.8 ± 5.1% 32 , LFAM2 is expected to be at least similar to, if not better than, LFAM in terms of cell viability.…”

“…2D where the flow paths go through filters except for those near the top and bottom elbows. As we discussed previously 32 , any mainstream ratio less than 50% ensures all fluid particles have opportunities to interact with lateral filters; and at 50% mainstream ratio, the flow path follows the serpentine channel with interactions with all filters in each following column.…”

“…However, www.nature.com/scientificreports/ www.nature.com/scientificreports/ there is no statistically significant difference (p < 0.05) between LFAM2 and GEM because of the large CTC variations among heterogeneous patient population. We also compared two sample preparation methods, (1) using Ficoll-Paque in this work and in the literature 39,40 , and (2) using whole blood with 2-time dilution 32,41 . As explained before, the 1:1 dilution of a blood sample with a DPBS buffer is to reduce the effects of viscosity variation among different patients on the flow characteristics in LFAM2 30,40 Fig.…”

Research Progress for the Clinical Application of Circulating Tumor Cells in Prostate Cancer Diagnosis and Treatment

“…Therefore, the basis of all studies of CTCs is separation and enrichment. The sorting used to isolate CTCs mainly includes physical methods [ 24 ], such as separation techniques based on cell volume, deformability, density, and membrane characteristics, as well as immunological methods, such as the detection of epithelial cell adhesion molecule (EpCAM) [ 25 ], cytokeratin (CK) [ 26 ], and epidermal growth factor receptor (EGFR) [ 27 ] expression. The only CTC separation and counting system certified by the US FDA is the CELLSEARCH System, which employs immunomagnetic beads coated with EpCAM.…”