Investigating intercellular calcium waves by microfluidic gated pinched-flow

In this paper, a new microfluidic approach, termed as gated pinched-flow (GPF), was developed for investigating cell-to-cell signaling dynamics coupling with optical imaging. It takes both advantages of conventional hydrodynamic gating and focusing, enabling precise on-chip chemical stimulation or perfusion upon targeted single cells among cells populations with high temporal (<50 ms) and spatial resolution. Theoretical model for GPF was first established and further validated by both numerical simulations and experiments. Stimulation of single HeLa cells was investigated to demonstrate the capability of the GPF for localized chemical stimulations of target single cells without interfering with adjacent cells. Guided by GPF, ATP-activated propagation of intercellular calcium waves (ICWs) among the seeded NIH-3T3 cells in the microchannel was then imaged with high repeatability. Inhibition investigations verified that those cell-to-cell calcium signals depended upon direct cytosolic transfer of molecules via gap junctions. The developed microfluidic method opens up a new avenue for cell-to-cell signaling studies and drug screening. (C) 2016 Elsevier B.V. All rights reserved.