Electrotaxis of oral squamous cell carcinoma cells in a multiple-electric-field chip with uniform flow field

Abstract

We report a new design of microfluidic chip (Multiple electric Field with Uniform Flow chip, MFUF chip) to create multiple electric field strengths (EFSs) while providing a uniform flow field simultaneously. MFUF chip was fabricated from poly-methyl methacrylates (PMMA) substrates by using CO2 laser micromachining. A microfluidic network with interconnecting segments was utilized to de-couple the flow field and the electric field (EF). Using our special design, different EFSs were obtained in channel segments that had an identical cross-section and therefore a uniform flow field. Four electric fields with EFS ratio of 7.9:2.8:1:0 were obtained with flow velocity variation of only 7.8% CV (coefficient of variation). Possible biological effect of shear force can therefore be avoided. Cell behavior under three EFSs and the control condition, where there is no EF, was observed in a single experiment. We validated MFUF chip performance using lung adenocarcinoma cell lines and then used the chip to study the electrotaxis of HSC-3, an oral squamous cell carcinoma cell line. The MFUF chip has high throughput capability for studying the EF-induced cell behavior under various EFSs, including the control condition (EFS = 0).

Evaluation of EGFR and RTK Signaling in the Electrotaxis of Lung Adenocarcinoma Cells under Direct-Current Electric Field Stimulation

“…In vitro transwell invasion assay has been performed on a clinical sample, CL1 tissue, to yield CL 1-5 cells, which has high invasiveness and anodal electrotaxis, and CL1-0 cells, which has low invasiveness and shows no electrotaxis [26,27,30,31]. …”

“…The CL 1-5 cells showed anodal electrotaxis while the CL1-0 cells showed no electrotaxis. To verify the involvement of serum in the electrotaxis of the CL-1-5 cells, the electrotaxis experiment was carried out in medium containing 10% FBS using the MFUF chip ( m ultiple-electric- f ield chip with u niform f low field) as previously reported [27]. Briefly, in MFUF chip, cell electrotaxis in three electric field strengths (EFS) and in the control condition (no electric field) are studied simultaneously in a single chip.…”

“…The data was plotted using the Ibidi chemotaxis and migration tool [44]. The definition of directedness and speed have been described in detail in the previous report [27]. Briefly, directedness is defined as average cosine of the angle included by the Euclidean distance vector and the EF vector.…”

The construction of an interfacial valve-based microfluidic chip for thermotaxis evaluation of human sperm

“…The electrotactic behavior of lung cancer cells and oral carcinoma cells were previously analyzed, respectively, using ordered three-dimensional scaffolds with direct current electric fields 18 and micro-channels with different electric fields but comparable flow velocities. 19 And T cell migration responding to the coexisting chemical gradient and direct current electric field was also measured. 20 Rupprecht et al fabricated a tapered channel to analyze the detachment kinetics and shear stressdependent motion of cells.…”

“…2 Recently, we developed novel microfluidic devices which integrate the entire IVF process, including oocyte positioning, sperm motility screening, fertilization, rapid medium replacement and debris expulsion, as well as long-term embryo culture. 16,17 Apart from sperm chemotaxis, the environmental conditiondirected motion of other kinds of cells, such as electrotaxis of cancer cells, 18,19 chemoelectrotaxis of T cells, 20 and shear stress-guided migration of cancer cells and bacteria, 21 were also investigated using various microsystems. Yet up until now there are no reports about any microdevices for the on-chip screening and trapping of thermotactic sperm.…”