Fig. 1.

(A) Diagram of CTC clusters occluding or transiting through capillary to seed metastases. (B) Microfluidic device schematic, 16 parallel microchannels of 5 × 5, 7 × 7, or 10 × 10-µm square cross-sections, designed to mimic capillary flow conditions (not to scale). (C) Experimental workflow: CTC clusters were isolated from breast or melanoma patient liquid biopsies (30). Patient clusters introduced into capillary devices directly or after ex vivo culture and spiking into whole blood. (D) Primary patient CTC cluster isolated from melanoma patient transiting through 10-µm capillary constriction under 7 cm H₂O at 37 °C. (E) Computational simulation (Top) and micrographs (Bottom) of four-cell LNCaP cluster in transit: (i) approach, (ii) unfold/elongate, (iii) travel, (iv) exit/reform through a 5-µm capillary constriction. (Scale bars: 50 µm.)