Cholangiocarcinoma (CCA) is highly metastatic, extremely difficult to diagnose and is consequently characterized by a low 5-year survival rate. Herein we investigated the potential of using exfoliated tumor cells (ETCs) in bile to serve as an early-warning CCA metastasis indicator. ETCs were isolated from bile using a CCA-specific aptamer conjugated to magnetic beads and identified via immunostaining (CK17+CK7+Hoechst+). A conventional protein biomarker, epithelial cell adhesion molecule (EpCAM), was used for comparison. Circulating tumor cell (CTC) isolation in blood was achieved by a microfluidic system from samples from five CCA patients undergoing chemotherapy, and the enumeration results of ETCs and CTCs were compared with diagnoses derived from computed tomography scans. The CCA-specific aptamer-conjugated magnetic beads effectively bound ETCs from bile samples of 40/40 CCA patients (>1 ETC in 3 ml of bile), and the ETC and CTC count data from patients corresponded well with cancer progression and tumor size. ETCs in bile could serve as promising indicators of disease status in early-advanced stage CCA while CTCs in blood could be representative of late-advanced stage CCA. The developed technique could consequently be a powerful tool in CCA diagnostics and prognostics.
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