(I-359) Breast Tumor Cell Migration under the Influence of Electric Field and Osmotic Pressure

Introduction:: MDA-231 cells are a type of highly malignant breast cancer tumor cells. Understanding their cell migration behavior can be key to developing new treatments. Previous studies on MDA-231 cells have looked into osmotic pressure and electric field respectively; yet, have not investigated both parameters simultaneously. Under osmotic pressure, MDA-231 cells were previously found to migrate towards the area of lower osmolarity. Additionally, previous studies also demonstrated that MDA-231 cells migrate towards the anode or higher voltage area under the influence of electric field.

Materials and Methods::

Upon obtaining MDA-231 cells, cells were cultured in medium containing 4% FBS and 1% penicillin/streptomycin in a 37 degrees celsius incubator under 5% CO2.  MDA-231 cells are passaged regularly for the different experiments. Cell migration experiments were then performed on well plates with PBS; then, a pair of copper electrodes were placed inside the solution along with the needle providing injection of distilled water. The well plate was placed under the Olympus microscope. Cells are then subjected to imaging for half an hour, with 10 frames taken every minute for the timelapse. After 6 minutes of starting recording, the electrical current and voltage are turned on with a voltage of approximately 15 V. Then, after another 12 minutes, 1 microliter of water is injected into the well plate to determine the effect of osmotic pressure under the influence of electric field. An additional trial to look into osmotic pressure is performed without using any electric field. After the videos are obtained, imageJ software is utilized to measure the distance traveled over time for the cells to determine the cell migration velocities as well as to measure the distance between the wires. 

Results, Conclusions, and Discussions:: Under the influence of direct current electric field about 81 V/cm, cells traveled at a velocity of 6.25 micrometers per minute towards the anode. This demonstrates consistency similar to previous studies. Then, both with and without the influence of the electric field, the cells migrated towards the injection area as well. However, the migration due to osmotic pressure was slightly faster under electric field compared to without electric field with average velocities of 22.083 micrometers per minute and 16.267 micrometers per minute respectively. Thus, we have demonstrated that electric fields can enhance the cell migration due to osmotic pressure gradients. Direct current electric field has been linked to an increase in intracellular calcium ion concentration as well as anodal polarization of the epidermal growth factor receptor in MDA-231 cells. Meanwhile, cell migration due to osmotic pressure can be linked to a mechanism of having net inflow of water at the cell leading edge and the net outflow of water at the trailing edge. This reveals that under both electric field and osmotic pressure simultaneously, both aquaporins and ion channels of the cell are perturbed, leading to a combined effect of having increased velocity. Future studies can then look into varying the strengths of the electric field along with varying the osmolarity of the injection. Additionally, studies can also look into whether electric fields can be applied to actual tumor patients as our studies focused on MDA-231 cells in a well which may behave differently compared to the same cells in the human body.

Acknowledgements (Optional): : This material is based upon work supported by the National Science Foundation under Grant No. 1852331.

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