Single Cell Analysis of Inertial Migration by Circulating Tumor Cells and Clusters

Abstract

Single-cell analysis provides a wealth of information regarding the molecular landscape of the tumor cells responding to extracellular stimulations, which has greatly advanced the research in cancer biology. In this work, we adapt such a concept for the analysis of inertial migration of cells and clusters, which is promising for cancer liquid biopsy, by isolation and detection of circulating tumor cells (CTCs) and CTC clusters. Using high-speed camera tracking live individual tumor cells and cell clusters, the behavior of inertial migration was profiled in unprecedented detail. We found that inertial migration is heterogeneous spatially, depending on the initial cross-sectional location. The lateral migration velocity peaks at about 25% of the channel width away from the sidewalls for both single cells and clusters. More importantly, while the doublets of the cell clusters migrate significantly faster than single cells (~two times faster), cell triplets unexpectedly have similar migration velocities to doublets, which seemingly disagrees with the size-dependent nature of inertial migration. Further analysis indicates that the cluster shape or format (for example, triplets can be in string format or triangle format) plays a significant role in the migration of more complex cell clusters. We found that the migration velocity of a string triplet is statistically comparable to that of a single cell while the triangle triplets can migrate slightly faster than doublets, suggesting that size-based sorting of cells and clusters can be challenging depending on the cluster format. Undoubtedly, these new findings need to be considered in the translation of inertial microfluidic technology for CTC cluster detection.

Numerical Modeling of Physical Cell Trapping in Microfluidic Chips

“…To evaluate trapping performance, it was important to assess the size of the A549 cells that we used in this work. A549 is a non-small-cell lung cancer (NSCLC) cell line that has been used to mimic lung cancer CTCs in prior studies [ 37 , 38 , 39 ]. A mean diameter of 17.27 ± 2.91 μm was measured for A549 cells, although others have reported smaller values closer to 15 μm [ 40 ].…”

The Role of Circulating Tumor Cells as a Liquid Biopsy for Cancer: Advances, Biology, Technical Challenges, and Clinical Relevance

“…This process, known as angiopellosis, allows them to retain their multicellular phenotype and effectively proliferate at distant sites, a phenomenon central to the Cancer Exodus Hypothesis [11,76,77,[81][82][83]. Advanced imaging and isolation techniques have been instrumental in observing these processes, revealing that CTC clusters exhibit unique molecular profiles that enhance their metastatic capabilities [13,31,[83][84][85][86].…”

“…Microfluidic devices allow for the precise manipulation of fluids at a micro-scale, improving the isolation and capture of CTCs. Nanotechnology, particularly the use of nanoparticles, can enhance the sensitivity of CTC detection by targeting specific tumor markers or properties [13,25,26,31,34,85].…”

“…An emerging area of interest in CTC research is the study of CTC clusters-groups of tumor cells bound together, traveling through the bloodstream. These clusters have been found to possess a higher metastatic potential compared to individual CTCs, offering new insights into the mechanisms of cancer spread and potential targets for therapeutic intervention [9][10][11][12][13].…”