Enhanced capture system for mesenchymal‑type circulating tumor cells using a polymeric microfluidic device ‘CTC‑Chip’ incorporating cell‑surface vimentin

CellSearch, the only approved epithelial cell adhesion molecule (EpCAM)‑dependent capture system approved for clinical use, overlooks circulating tumor cells (CTCs) undergoing epithelial‑mesenchymal transition (EMT‑CTCs), which is considered a crucial subtype responsible for metastasis. To address this limitation, a novel polymeric microfluidic device 'CTC‑chip' designed for the easy introduction of any antibody was developed, enabling EpCAM‑independent capture. In this study, antibodies against EpCAM and cell surface vimentin (CSV), identified as cancer‑specific EMT markers, were conjugated onto the chip (EpCAM‑chip and CSV‑chip, respectively), and the capture efficiency was examined using lung cancer (PC9, H441 and A549) and colon cancer (DLD1) cell lines, classified into three types based on EMT markers: Epithelial (PC9), intermediate (H441 and DLD1) and mesenchymal (A549). PC9, H441 and DLD1 cells were effectively captured using the EpCAM‑chip (average capture efficiencies: 99.4, 88.8 and 90.8%, respectively) when spiked into blood. However, A549 cells were scarcely captured (13.4%), indicating that EpCAM‑dependent capture is not suitable for mesenchymal‑type cells. The expression of CSV tended to be higher in cells exhibiting mesenchymal properties and A549 cells were effectively captured with the CSV‑chip (72.4 and 88.4% at concentrations of 10 and 100 µg/ml, respectively) when spiked into PBS. When spiked into blood, the average capture efficiencies were 27.7 and 46.8% at concentrations of 10 and 100 µg/ml, respectively. These results suggest that the CSV‑chip is useful for detecting mesenchymal‑type cells and has potential applications in capturing EMT‑CTCs.