A Controllable, Centrifugal-Based Hydrodynamic Microfluidic Chip for Cell-Pairing and Studying Long-Term Communications between Single Cells.

Investigation of cell-cell interactions between individual cells in a well-defined microenvironment is critical for the understanding of specific intercellular communications and interactions. However, most current studies in multicellular systems are often overwhelmed by additional complicated interactions. Cell-pairing based on a microfluidic chip provides a potential strategy to simplify the studies. Here, we report a robust and straightforward method, relying on a combination of hydrodynamic single-cell capture and centrifugation-assisted relocation of individual cells, which can be applied, in general, to various cell types for cell-pairing and studying cell interactions at the single-cell level. This microfluidic chip is simple to operate and easily controlled, which requires only two operational steps-capturing individual cells with hydrodynamic traps and subsequently relocating the capture cells by centrifugation. With this microfluidic chip, we demonstrated homotypic cell-pairing, heterotypic cell-pairing, and long-term cell coculture, which exhibited better or comparable performance compared with previous cell-pairing methods. Its single-cell trapping and cell-pairing efficiencies are ∼74% and ∼20%, respectively. As a proof of concept, we paired individual dHL-60 cells and HeLa cells (HeLa-IL8, HeLa-IL10, and wild-type HeLa cells) in multiple cell chambers. The HeLa-IL8 and HeLa-IL10, both engineered with a light-induced gene expression system, can secret interleukin-8 and interleukin-10, respectively, under blue light illumination. We found that these three HeLa cell lines have very different influences on the migration of dHL-60 cells. This platform demonstrates its potential applications in studies of intercellular communication (paracrine), and it can be extended to trap three or more individual cells for more complex biological systems.