The combination of hexagonal microfluidic devices and cell-based reporter cells allows detection of cytokine-producing cells at the single-cell level

Abstract

Cytokine production analysis at the single-cell level, such as detection of type I interferon (IFN-I), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) producing cells, is beneficial in clinical diagnostics and drug discovery. In this work, we developed a microfluidic device with hexagonal microchambers capable of generating single-cell/multicellular systems, oil-droplet compartmentalization, and performing functional assays based on green fluorescent protein (GFP) expression or secreted embryonic alkaline phosphatase (SEAP) secretion for cytokine secretion detection at single-cell level. Since the droplets are stationary, cell/cell-pairs are identified, and real-time monitoring and end-point analysis can be performed. At optimized conditions, up to 60% single-cell chamber occupancy can be achieved. Cytokines such as IFN-I, TNF-α, and IL-6 secreted by human immune cells (THP1 cells, plasmacytoid dendritic cells (pDCs), T-cells, B-cells, and monocytes) can be detected at the single-cell level upon pairing with GFP and SEAP expressing Human Embryonic Kidney (HEK)− 293 reporter cells. This proof-of-concept device has the potential to evaluate single-cell behaviors and could benefit the field of single-cell cytokine secretion monitoring.