Microfluidic recapitulation of circulating tumor cell-neutrophil clusters <i>via</i> double spiral channel-induced deterministic encapsulation.

Abstract

Circulating tumor cell (CTC)-neutrophil clusters are highly potent precursors of cancer metastasis. However, their rarity in patients' blood has restricted research thus far, and moreover, studies on <i>in vitro</i> methods for mimicking cell clusters have generally neglected <i>in vivo</i> conditions. Here, we introduce an inertial-force-assisted droplet microfluidic chip that allows the recapitulation of CTC-neutrophil clusters in terms of physical as well as biochemical features. The deterministic encapsulation of cells <i>via</i> double spiral channels facilitates the pairing of neutrophils and cancer cells with ratios of interest (from 1 : 1 to 1 : 3). The encapsulated cells are spontaneously associated to form clusters, achieving the physical emulation of CTC-neutrophil clusters. Furthermore, the molecular signatures of CTC-neutrophil clusters (<i>e.g.</i>, their E-cadherin, VCAM-1, and mRNA expressions) were well defined. Our novel microfluidic platform for exploring CTC-neutrophil clusters can therefore play a promising role in cancer-metastasis studies.