A microfluidic device for differential capture of heterogeneous rare tumor cells with epithelial and mesenchymal phenotypes

Abstract

Accumulating evidence suggests that the features associated with epithelial to mesenchymal transition (EMT) in circulating tumor cells (CTCs) reflect intrinsic metastatic potential and associate with therapy resistance. Thus, profiling the EMT phenotypes of CTCs is increasingly important for cancer diagnosis and prediction of therapeutic responses. However, rapid assessment of the EMT status of a global CTC population is still a challenge due to the difficulty in enriching and phenotyping CTCs simultaneously. Here, we report a microfluidic device consisting of an enrichment section and a capture section for differential capture of rare tumor cells from blood according to their EMT phenotypes. A row of micropillars was constructed in the enrichment section to provide cross-flows for the size-dependent filtration of cells. Thus, MCF-7 and MDA-MB-231 tumor cells mimicking CTCs were first separated from white blood cells through the micropillars and continually flowed into the capture section at a reduced velocity under a differential hydrodynamic pressure. In the capture section, the heterogeneous tumor cells were then phenotypically sorted and captured in two cascaded compartments functionalized with either an anti-EpCAM antibody or a cocktail of antibodies against mesenchymal markers including Axl, PD-L1, and EGFR. Direct counting of the captured cells in each compartment resulted in the enumeration of epithelial and mesenchymal subpopulations of the tumor cells without additional labeling. Furthermore, the captured tumor cells were successfully maintained for up to six days in the device with high viability and marked proliferation for downstream analysis. Thus, this integrated microfluidic device may have great potential in phenotyping EMT status of CTCs for precision cancer therapy.