A common problem with cancer treatment is the development of treatment resistance and tumor recurrence that result from treatments that kill most tumor cells yet leave behind aggressive cells to repopulate. Presented here is a microfluidic device that can be used to isolate tumor subpopulations to optimize treatment selection. Dielectrophoresis (DEP) is a phenomenon where particles are polarized by an electric field and move along the electric field gradient. Different cell subpopulations have different DEP responses depending on their bioelectrical phenotype, which, we hypothesize, correlate with aggressiveness. We have designed a microfluidic device in which a region containing posts locally distorts channel of the electric field created by an AC voltage across a microfluidic channel and which forces cells toward the posts through DEP. This force is balanced with a simultaneous drag force from fluid motion that pulls cells away from the posts. We have shown that by adjusting the drag force, cells with aggressive phenotypes are influenced more by the DEP force and trap on posts while others flow through the chip unaffected. Utilizing single-cell trapping on cell-sized posts by a drag-DEP force balance, we show that separation of very similar cell subpopulations may be achieved, a result that was previously impossible with DEP alone. Separated subpopulations maintain high viability downstream, and remain in a native state, without fluorescent labeling. These cells can then be cultured to help select a therapy that kills aggressive subpopulations equally or better than the bulk of the tumor, mitigating resistance and recurrence.
Cancer stem cells (CSCs) are aggressive subpopulations with increased stem‐like properties. CSCs are usually resistant to most standard therapies and are responsible for tumor repropagation. Similar to normal stem cells, isolation of CSCs is challenging due to the lack of reliable markers. Antigen‐based sorting of CSCs usually requires staining with multiple markers, making the experiments complicated, expensive, and sometimes unreliable. Here, we study the feasibility of using dielectrophoresis (DEP) for isolation of glioblastoma cells with increased stemness. We culture a glioblastoma cell line in the form of neurospheres as an in vitro model for glioblastoma stem cells. We demonstrate that spheroid forming cells have higher expression of stem cell marker, nestin. Next, we show that dielectric properties of neurospheres change as a result of changing culture conditions. Our results indicate that spheroid forming cells need higher voltages to experience the same DEP force magnitude compared to normal monolayer cultures of glioblastoma cell line. This study confirms the possibility of using DEP to isolate glioblastoma stem cells.
Background: This study presents a label-free method of separating macrophages and fibroblasts, cell types critically associated with tumors. Materials and Methods: Contactless dielectrophoresis (DEP) devices were used to separate fibroblasts from macrophages by selectively trapping one population. An ImageJ macro was developed to determine the percentage of each population moving or stationary at a given point in time in a video. Results: At 350V rms , 20 kHz, and 1.25 lL/min, more than 90% of fibroblasts were trapped while less than 20% of macrophages were trapped. Conclusions: Contactless DEP was used to study macrophage and fibroblast separation as a proof-of-concept study for separating cells in the tumor microenvironment. The associated ImageJ macro could be used in other microfluidic cell separation studies.
Electrophoresis 2017, 38, 1507–1514. DOI: https://doi.org/10.1002/elps.201600530
The back cover picture shows an artistic rendition of the electric field magnitude around insulating posts in a contactless dielectrophoresis microfluidic chip. The insulating posts create a perturbation in the electric field to induce dielectrophoresis. When this force is optimally balanced with the drag forces produced by the flow of the cancer cell sample through the device, cells trap depending on their biophysical properties. This potentially allows for the separation of cancer cells into subpopulations depending on cell malignancy. The results of this experiment could have applications in precision medicine.
With the modern and rapid development of the internet, people's connections are more important than ever, and they're looking for new ways to communicate with one another in real time. WebRTC is a futuristic technology that enables realtime communication in audio, video, and data transmission through web browsers without the need for a plugin by using JavaScript APIs (Application Programming Interface). In this paper, we present a web peer-to-peer real-time communication system that allows users to communicate across a communication channel with high-speed data transmission using WebRTC technology, HTML5, and a Node.js server address. The outcome demonstrates that the system is stable, fully functioning, and secure. Keywords: WebRTC, Vide o Conferencing Application, Peer to Peer
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