light-induced-dielectrophoresis-for-characterizing-electrical

Light-Induced Dielectrophoresis for Characterizing the Electrical Behavior of Human Mesenchymal Stem Cells

Human mesenchymal stem cells (hMSCs) offer a patient-derived cell source for conducting mechanistic studies of diseases or for several therapeutic ...

University of California, Irvine

Whole cell membrane capacitance is an electrophysiological property of the plasma membrane that serves as a biomarker for stem cell fate potential. Neural stem and progenitor cells (NSPCs) that differ in ability to form neurons or astrocytes are distinguished by membrane capacitance measured by dielectrophoresis (DEP). Differences in membrane capacitance are sufficient to enable the enrichment of neuron- or astrocyte-forming cells by DEP, showing the separation of stem cells on the basis of fate potential by membrane capacitance. NSPCs sorted by DEP need not be labeled and do not experience toxic effects from the sorting procedure. Other stem cell populations also display shifts in membrane capacitance as cells differentiate to a particular fate, clarifying the value of sorting a variety of stem cell types by capacitance. Here, we describe methods developed by our lab for separating NSPCs on the basis of capacitance using several types of DEP microfluidic devices, providing basic information on the sorting procedure as well as specific advantages and disadvantages of each device.

Separation of neural stem cells by whole cell membrane capacitance using dielectrophoresis.

Human neural stem and progenitor cells (hNSPCs) have therapeutic potential to treat neural diseases and injuries since they provide neuroprotection and differentiate into astrocytes, neurons, and oligodendrocytes. However, cultures of hNSPCs are heterogeneous, containing cells linked to distinct differentiated cell fates. HNSPCs that differentiate into astrocytes are of interest for specific neurological diseases, creating a need for approaches that can detect and isolate these cells. Astrocyte-biased hNSPCs differ from other cell types in electrophysiological properties, namely membrane capacitance, and we hypothesized that this could be used to enrich these cells using dielectrophoresis (DEP). We implemented a two-step DEP sorting scheme, consisting of analysis to define the optimal sorting frequency followed by separation of cells at that frequency, to test whether astrocyte-biased cells could be separated from the other cell types present in hNSPC cultures. We developed a novel device that increased sorting reproducibility and provided both enriched and depleted cell populations in a single sort. Astrocyte-biased cells were successfully enriched from hNSPC cultures by DEP sorting, making this the first study to use electrophysiological properties for label-free enrichment of human astrocyte-biased cells. Enriched astrocyte-biased human cells enable future experiments to determine the specific properties of these important cells and test their therapeutic efficacy in animal models of neurological diseases.

Label-free enrichment of fate-biased human neural stem and progenitor cells.

Electrical impedance spectroscopy (EIS) is an electrokinetic method that allows for the characterization of intrinsic dielectric properties of cells. EIS has emerged in the last decade as a promising method for the characterization of cancerous cells, providing information on inductance, capacitance, and impedance of cells. The individual cell behavior can be quantified using its characteristic phase angle, amplitude, and frequency measurements obtained by fitting the input frequency-dependent cellular response to a resistor-capacitor circuit model. These electrical properties will provide important information about unique biomarkers related to the behavior of these cancerous cells, especially monitoring their chemoresistivity and sensitivity to chemotherapeutics. There are currently few methods to assess drug resistant cancer cells, and therefore it is difficult to identify and eliminate drug-resistant cancer cells found in static and metastatic tumors. Establishing techniques for the real-time monitoring of changes in cancer cell phenotypes is, therefore, important for understanding cancer cell dynamics and their plastic properties. EIS can be used to monitor these changes. In this review, we will cover the theory behind EIS, other impedance techniques, and how EIS can be used to monitor cell behavior and phenotype changes within cancerous cells.

Article	Year
Separation of neural stem cells by whole cell membrane capacitance using dielectrophoresis. Methods (San Diego, Calif.)\| PubMed ID: 28864355	2018
Label-free enrichment of fate-biased human neural stem and progenitor cells. Biosensors & bioelectronics\| PubMed ID: 32056730	2020
Electrical Impedance Spectroscopy for Monitoring Chemoresistance of Cancer Cells. Micromachines\| PubMed ID: 32878225	2020

Tayloria N. G. Adams

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