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.