Progression of change in membrane capacitance and cytoplasm conductivity of cells during controlled starvation using dual-frequency DEP cytometry

Afshar, Samaneh; Salimi, Elham; Fazelkhah, Azita; Braasch, Katrin; Mishra, Neha; Butler, Michael; Thomson, D. J.; Bridges, Greg E.

doi:10.1016/j.aca.2019.01.046

Cited by 18 publications

(11 citation statements)

References 44 publications

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“…If the nutrient deprivation is extended beyond 36 hr, cells become apoptotic and are no longer able to restore the cytoplasm conductivity to the normal viable level with the reintroduction of nutrients. A much greater loss in ions and hence decrease in cytoplasm conductivity occurs for apoptotic cells (Afshar et al, ; Hughes, Bortner, Purdy, & Cidlowski, ; Labeed, Coley, & Hughes, ; McCarthy & Cotter, ; Mulhall, Cardnell, Hoettges, Labeed, & Hughes, ; Salimi et al, ; Yu, Canzoniero, & Choi, ). At 48 hr when glucose is reintroduced to the medium, no significant change in the status of cells is observed and the increase in conductivity is minimal.…”

Section: Resultsmentioning

confidence: 99%

“…In our previous work, we employed a single cell DEP technique to study the change in the cytoplasm conductivity of cells (Salimi et al, ). We showed that nutrient depletion in the culture was associated with a decrease in dielectric response of the cells and closely correlated with the cells’ cytoplasm conductivity (Afshar et al, ; Salimi et al, ).…”

Section: Introductionmentioning

confidence: 95%

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Cytoplasmic conductivity as a marker for bioprocess monitoring: Study of Chinese hamster ovary cells under nutrient deprivation and reintroduction

Fazelkhah

Afshar

Braasch

et al. 2019

Biotech & Bioengineering

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The ability to monitor the status of cells during nutrient limitation is important for optimizing bioprocess growth conditions in batch and fed‐batch cultures. The activity level of Na+/K+ ATPase pumps and cytoplasm ionic concentrations are directly influenced by the nutrient level, and thus, cytoplasm conductivity can be used as a markerless indicator of cell status. In this work, we monitored the change in cytoplasm conductivity of Chinese hamster ovary (CHO) cells during nutrient deprivation and reintroduction. Employing single cell dielectrophoresis, the change in cytoplasm conductivity was measured over a 48‐hr period. The conditions under which the cytoplasm conductivity would recover to a normal level after nutrient reintroduction was determined. In addition, numerical simulations of cell ion flux, for different levels of Na+/K+ ATPase pump inhibition, were used to predict the minimum conductivity expected for nutrient‐deprived CHO cells. This predicted value is close to the minimum observed experimental cytoplasm conductivity for CHO cells that maintain the ability to restore the cytoplasm conductivity to the normal viable levels when nutrients are reintroduced. The recovery of starved cells was verified by reintroducing them to nutrient for 36 hr and measuring their proliferation using trypan blue exclusion assay. We conclude that cytoplasm conductivity can be used as a marker to indicate whether cells are in a recoverable state, such that the reintroduction of nutrients results in cells returning to a normal healthy state.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Cytoplasmic conductivity as a marker for bioprocess monitoring: Study of Chinese hamster ovary cells under nutrient deprivation and reintroduction

Fazelkhah

Afshar

Braasch

et al. 2019

Biotech & Bioengineering

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“…Afshar et al employed a dual frequency, levitation technique to monitor apoptosis in CHO cells undergoing controlled starvation. Here, they used literature values to predetermine appropriate frequencies to monitor both membrane capacitance and cytoplasmic conductivity as a function of apoptotic state [90]. Sano et al relied on literature values to apply dielectrophoretic characterization to cancer cells in order to investigate the cell separation efficacy of their 3D contactless‐DEP device [91].…”

Section: Dep Characterization Methods and Parametersmentioning

confidence: 99%

“…This increase in parameters is, however, counter to other studies. For example, Afshar et al measured apoptosis progression of CHO cells and found decrease in membrane capacitance and cytoplasmic conductivity [90].…”

Section: Dep Characterization Methods and Parametersmentioning

confidence: 99%

Review: Dielectrophoresis in cell characterization

Henslee

2020

Electrophoresis

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Many cellular functions are affected by and thus can be characterized by a cell's electrophysiology. This has also been found to correspond to other biophysical parameters such as cell morphology and mechanical properties. Dielectrophoresis (DEP) is an electrostatic technique which can be used to examine cellular biophysical parameters through the measuring of single or multiple cell response to electric field induced forces. This label‐free method offers many advantages in characterizing a cell population over conventional electrophysiology methods such as patch clamping; however, it has yet to see mainstream pharmacological application. Challenges such as the transdisciplinary nature of the field bridging engineering and the biological sciences, throughput, specificity as well as standardization are being addressed in current literature. This review focuses on the developments of DEP‐based cell electrophysiological characterization where determining cellular properties such as membrane conductance and capacitance, and cytoplasmic conductivity are the primary motivation. A brief theoretical review, techniques for obtaining these cell parameters, as well as the resulting cell parameters and their applications are included in this review. This review aims to further support the development of DEP‐based cell characterization as an important part of the future of DEP and electrophysiology research.

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“…DEP has been applied to the identification of different cell types in blood analysis [1–3], single‐cell manipulation [4], identification and isolation of circulating tumor cells [5–7], differentiation of cancerous cells from healthy ones [8,9], identification of different types of cultured tumor cells [3,10], characterization of biological cells [11,12], characterization of the breast cancer cells [13], stem cell differentiation and separation [14–17], tracking apoptosis, and monitoring the effects of nutrient deprivation [12,18–22]. For example, apoptosis dramatically changes ion concentrations in the cytoplasm as well as the effective surface area of the cell membrane and, consequently, its cytoplasm conductivity and membrane capacitance [19,22–28]. DEP has the advantage of being label‐free compared to techniques such as flow cytometry and magnetic bead attachment technologies.…”

Section: Introductionmentioning

confidence: 99%

Parallel single‐cell optical transit dielectrophoresis cytometer

et al. 2020

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In this work, we present an optical transit DEP flow cytometer for parallel single-cell analysis. Each cell's dielectric property is inferred from velocity perturbations due to DEP actuation in a microfluidic channel. Dual LED sources facilitate velocity measurement by producing two transit shadows for each cell passing through the channel. These shadows are detected using a 256-pixel linear optical array detector. Massively parallel analysis is possible as each pixel of the detector can independently analyze the passing cells. A wide channel (∼18 mm) was employed to carry many particles simultaneously, and the system was capable of detecting the velocity of over 200 cells simultaneously. We have achieved analysis rates for 10 µm diameter polystyrene spheres response exceeding 250 per second. With appropriate calibration, this DEP cytometer can quantitatively measure the dielectric response. The dielectric response (Clausius-Mossotti factor) of viable CHO cells was measured over the frequency range of 100 kHz to 6 MHz, and the obtained response matches the previously measured values by our group. The DEP cytometer uses simple modular components to achieve high throughput label-free single-cell dielectric analysis and can begin analyzing particles within 10 s after starting to pump the sample into the channel.

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Progression of change in membrane capacitance and cytoplasm conductivity of cells during controlled starvation using dual-frequency DEP cytometry

Cited by 18 publications

References 44 publications

Cytoplasmic conductivity as a marker for bioprocess monitoring: Study of Chinese hamster ovary cells under nutrient deprivation and reintroduction

Cytoplasmic conductivity as a marker for bioprocess monitoring: Study of Chinese hamster ovary cells under nutrient deprivation and reintroduction

Review: Dielectrophoresis in cell characterization

Parallel single‐cell optical transit dielectrophoresis cytometer

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