Analysis of U87 glioma cells by dielectrophoresis

Abstract

Glioblastoma multiforme is the most aggressive and invasive brain cancer consisting of genetically and phenotypically altering glial cells. It has massive heterogeneity due to its highly complex and dynamic microenvironment. Here, electrophysiological properties of U87 human glioma cell line were measured based on a dielectrophoresis phenomenon to quantify the population heterogeneity of glioma cells. Dielectrophoretic forces were generated using a gold‐microelectrode array within a microfluidic channel when 3 Vpp and 100, 200, 300, 400, 500 kHz, 1, 2, 5, and 10 MHz frequencies were applied. We analyzed the dielectrophoretic behavior of 500 glioma cells, and revealed that the crossover frequency of glioma cells was around 140 kHz. A quantifying dielectrophoretic movement of the glioma cells exhibited three distinct glioma subpopulations: 50% of the glioma cells experienced strong, 30% of the cells were spread in the microchannel by moderate, and the rest of the cells experienced very weak positive dielectrophoretic forces. Our results demonstrated the dielectrophoretic spectra of U87 glioma cell line. Dielectrophoretic responses of glioma cells linked population heterogeneity to membrane properties of glioma cells rather than their size distribution in the population.

Quantifying Deformation and Migration Properties of U87 Glioma Cells Using Dielectrophoretic Forces

“…Next, the low conductive DEP buffer consisting of 8.6% sucrose (BioFroxx, Hesse, Germany), 0.3% glucose (Sigma Aldrich, St. Louis, MI, USA), and 0.1% Bovine Serum Albumin (BSA, PAN-Biotech, Bayern, Germany) was prepared in deionized water. The conductivity value of the suspension was set to 20 µS/cm verified by measuring a conductivity meter (CORNING, 311 Conductivity, Merck KGaA, Darmstadt, Germany) [ 43 , 44 ]. Afterwards, glioma cells were spun down at 3000 rpm (Hettich EBA 20 Centrifuge, Merck KGaA, Darmstadt, Germany) for 5 min to wash the cells using the DEP buffer twice.…”

“…The DEP chip consists of 65 pairs of electrodes in an interdigitated organization to generate a non-uniform electric field. The gold electrodes were fabricated at 40-nm height, 1.8-mm length, and 60-µm width using the lift-off process as detailly reported by Sengul et al [ 44 ], Figure 1 A. We used a cutting plotter machine (Graphtech CE6000-40, Yokohama, Japan) to create a 100-µm thick microfluidic channel on the electrode array using a double-sided pressure-sensitive adhesive sheet (PSA).…”

“…We assembled the device using a 3-mm thick polymethyl methacrylate (PMMA) layer, Figure 1 B. To introduce the cells into the device, we used a CO 2 Laser-Engraving machine (ULS Versa Laser 3.50, 10.6 µm wavelength) to make an inlet and outlet on the PMMA cover [ 44 ].…”

“…Prior to loading the glioma cells into DEP device, we sterilized the device using 70% isopropyl alcohol and rinsed the device with deionized water and the DEP buffer, respectively [ 43 , 44 ]. In addition, we used the DEP buffer to remove bubbles from the electrode array.…”

Microwave Radiation and the Brain: Mechanisms, Current Status, and Future Prospects

“…It is well established that U87 MG is a highly sensitive brain cancer cell line [ 159 ]. Recent studies have suggested that cold plasma plays a significant role in U87 MG [ 160 ], specifically via the total mitogen-activated protein kinase (MAPK) signaling pathway [ 140 , 158 ] without affecting normal cells.…”