Simultaneous chemical and electrical stimulation on lung cancer cells using a multichannel-dual-electric-field chip

Electrotaxis has been identified as an important biological phenomenon in living organisms. Various types of cells respond to electrical stimuli by moving toward anode or cathode. However, the molecular mechanisms of cell migration under electric field still remain unclear. Many different microfluidic devices for electrotaxis studies have been reported in recent years. Yet, a device that allows rapid study of simultaneous chemical and electric-field (EF) effect on cells is not available. In this study, we report a multichannel-dual-electric-field (MDF) chip to investigate the concurrent effect of chemicals and EF on lung cancer cells. The chip provided 8 combinations of electrical/chemical stimulations in one experiment. The MDF chip is a poly-methylmethacrylate based microfluidic cell culture chip that integrates electrical stimulation and several chemically isolated channels. Alternatively, the chemically isolated channels can be filled with different types of cells in one experiment. The EF in these different channels was applied using one electrical power supply. Each chemically isolated channel has two segments possessing dual independent electric-fields, one with the applied electric-field strength (EFS) and the other with 0 EFS. In addition, a new design that includes on-chip salt bridges into the MDF chip provides better-controlled coexisting EF and chemical stimulation. Numerical simulation was conducted to verify the independency of the isolated channels and the dual EFS in the two segments of each channel. A highly metastasized lung cancer cell line, CL1-5 cell, was used to demonstrate the function of the chip. Our results showed that, after treating cells with phosphatidylinositide 3-kinases (PI3K) blocker (LY294002), both the migration speed and the directedness toward to anode were reduced for the electrically stimulated CL1-5 cells. However, suppressing Rho-associated coiled-coil kinase (ROCK) in the EF stimulated CL1-5 cells by Y27632, a ROCK inhibitor, only eliminated the directedness of electrotropism but showed no effect on the cell migration speed. The result suggests that ROCK, but not PI3K pathway, is more likely to be involved in directing the anodic migration of CL1-5 cells under electrical stimulation. Using the MDF chip, multiple combinations of chemical/EF stimulation was studied in one experiment. The dose dependency experiment of a chemical was also rapidly conducted. We expect the MDF chip will greatly shorten the experiment time and increase the accuracy of the electrotaxis studies.