Design of the microfluidic device. PDMS slab with moulded channel features was mounted on a glass coverslip and then placed at the stage of a fluorescence microscope. The fluid streams of the 3 channels are indicated by three different color lines.
Control of cellular microenvironment by microfluidics. (a) Lateral diffusion of Lucifer yellow is absent between two streams of fluids in the microfluidic channel. (b) Treatment of a subpopulation of MCF-7 cells with tamoxifen by microfluidics depolarizes the mitochondrial membrane potential (ΔΨm). Note the strong change in fluorescence intensity at the interface of channels 2 and 3, which is illustrated for the junction and a downstream area (dotted lines). Scale bars, 50 μm.
Temporal analysis of tamoxifen-induced bystander effects. (a) Bystander cells (treatment) show a progressive loss of TMRM fluorescence with increasing culture time. Scale bars, 50 μm. (b) The graph shows the changes in ΔΨm of bystander cells by quantitative analysis of TMRM fluorescence intensity.
Spatial analysis of tamoxifen-induced bystander effects. (a) Quantitative analysis of ΔΨm in bystander cells at different distances upstream from the junction. (b) A cell-free region was generated between tamoxifen-treated and non-treated cells. (c) Quantitative analysis of ΔΨm in bystander cells lacking physical contact to drug-treated cells. (d) Spatial analysis of ΔΨm in bystander cells without physical contact to drug-treated cells.
The bystander cells show phosphatidylserine exposure. Cells in channels were stained with annexin V-Alexa Fluor 488 36 h after tamoxifen treatment. Both targeted and bystander cells were annexin V positive (arrowheads). Scale bars, 50 μm.
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