PillarX: A Microfluidic Device to Profile Circulating Tumor Cell Clusters Based on Geometry, Deformability, and Epithelial State

Abstract

Circulating tumor cell (CTC) clusters are associated with increased metastatic potential and worse patient prognosis, but are rare, difficult to count, and poorly characterized biophysically. The PillarX device described here is a bimodular microfluidic device (Pillar‐device and an X‐magnetic device) to profile single CTCs and clusters from whole blood based on their size, deformability, and epithelial marker expression. Larger, less deformable clusters and large single cells are captured in the Pillar‐device and sorted according to pillar gap sizes. Smaller, deformable clusters and single cells are subsequently captured in the X‐device and separated based on epithelial marker expression using functionalized magnetic nanoparticles. Clusters of established and primary breast cancer cells with variable degrees of cohesion driven by different cell‐cell adhesion protein expression are profiled in the device. Cohesive clusters exhibit a lower deformability as they travel through the pillar array, relative to less cohesive clusters, and have greater collective invasive behavior. The ability of the PillarX device to capture clusters is validated in mouse models and patients of metastatic breast cancer. Thus, this device effectively enumerates and profiles CTC clusters based on their unique geometrical, physical, and biochemical properties, and could form the basis of a novel prognostic clinical tool.

Recent progress of nanostructure-based enrichment of circulating tumor cells and downstream analysis

“…Green et al designed a dual-mode microfluidic device PillarX consisting of a series of cylindrical devices and X-devices, which can analyze a single CTC and cluster in whole blood according to the size, deformability and epithelial marker expression of a single CTC and cluster. 129 Larger, cohesive and less easily deformed clusters and larger individual cells are captured in the column device and classified according to the size of the column gap. Smaller, deformable clusters and individual cells are then captured in X-ray devices, and separated using functionalized magnetic nanoparticles according to the expression of epithelial markers.…”

Insights into Circulating Tumor Cell Clusters: A Barometer for Treatment Effects and Prognosis for Prostate Cancer Patients

“…Surprisingly, they observed that some of the clusters could maintain weak intercellular adhesion. These clusters re-arranged their shape to travel through the pillars, and then clusters re-formed in the X-magnetic device [ 83 ]. This process provided direct evidence that CTC cluster cohesion can be regulated by the dynamic expression of E-cadherin, as reflected by the adaptive alteration of cluster shapes.…”

Nanoparticle Amplification Labeling for High-Performance Magnetic Cell Sorting

“…The MagRC device eventually generates a spatial profile of cell distribution that can be read out by microscopy and is capable of visualizing a small shift of marker expression in rare cells, which is highly associated with bioprocesses underneath, such as metastasis . The MagRC approach is highly biocompatibleaccording to the simulation we performed previously, the shear stress under a flow rate of 5 mL/h is 0.0004 Pa within the device . This value is relatively ignorable in comparison to the shear stress generated by the FACS sorting nozzle (typically 1–30 Pa) .…”

“…19 The MagRC approach is highly biocompatibleaccording to the simulation we performed previously, the shear stress under a flow rate of 5 mL/h is 0.0004 Pa within the device. 34 This value is relatively ignorable in comparison to the shear stress generated by the FACS sorting nozzle (typically 1−30 Pa). 34 Hence, the cells after the MagRC are highly viable and phenotypically natural.…”

“…34 This value is relatively ignorable in comparison to the shear stress generated by the FACS sorting nozzle (typically 1−30 Pa). 34 Hence, the cells after the MagRC are highly viable and phenotypically natural. 7,22 MagRC has been widely used in our laboratory to phenotypically profile rare cell types, such as circulating tumor cells (CTCs), on the basis of the expression level of surface 19 and intracellular proteins.…”