Analysis of intercellular communication by flexible hydrodynamic gating on a microfluidic chip

Intercellular Ca²⁺ waves are propagation of Ca²⁺ transients among cells that could be initiated by chemical stimulation. Current methods for analyzing intercellular Ca²⁺ waves are difficult to realize localized chemical stimulations upon the target cell without interfering with adjacent contacting cells. In this paper, a simple and flexible microfluidic method was developed for investigating the intercellular communication of Ca²⁺ signals. A cross-patterned microfluidic chip was designed and fabricated with polydimethylsiloxane as the structural material. Localized chemical stimulation was achieved by a new strategy based on hydrodynamic gating technique. Clusters of target cells were seeded at the location within 300 μm downstream of the intersection of the cross-shaped microchannel. Confined lateral molecular diffusion largely minimized the interference from diffusion-induced stimulation of adjacent cells. Localized stimulation of the target cell with adenosine 5′-triphosphate successfully induced the propagation of intercellular Ca²⁺ waves among a population of adjacent contacting cells. Further inhibition studies verified that the propagation of calcium signals among NIH-3 T3 cells was dependent on direct cytosolic transfer via gap junctions. The developed microfluidic method provides a versatile platform for investigating the dynamics of intercellular communications.