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D M Campos C, Uning KT, Barmuta P, Markovic T, Yadav R, Mangraviti G, Ocket I, Van Roy W, Lagae L, Liu C. Use of high frequency electrorotation to identify cytoplasmic changes in cells non-disruptively. Biomed Microdevices 2023; 25:39. [PMID: 37801137 DOI: 10.1007/s10544-023-00677-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2023] [Indexed: 10/07/2023]
Abstract
In this paper we demonstrate how the use of frequencies ranging from 50 kHz to 5 GHz in the analysis of cells by electrorotation can open the path to the identification of differences not detectable by conventional set-ups. Earlier works usually reported electrorotation devices operating below 20 MHz, limiting the response obtained to properties associated with the cell membrane. Those devices are thus unable to resolve the physiological properties in the cytoplasm. We used microwave-based technology to extend the frequency operation to 5 GHz. At high frequencies (from tens of MHz to GHz), the electromagnetic signal passes through the membrane and allows probing the cytoplasm. This enables several applications, such as cell classification, and viability analysis. Additionally, the use of conventional microfabrication techniques reduces the cost and complexity of analysis, compared to other non-invasive methods. We demonstrated the potential of this set-up by identifying two different populations of T-lymphocytes not distinguishable through visual assessment. We also assessed the effect of calcein on cell cytoplasmic properties and used it as a controlled experiment to demonstrate the possibility of this method to detect changes happening predominantly in the cytoplasm.
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Affiliation(s)
- Camila D M Campos
- imec, Kapeldreef 75, 3001, Leuven, Belgium.
- Department Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001, Leuven, Belgium.
| | - Kevin T Uning
- imec, Kapeldreef 75, 3001, Leuven, Belgium
- Institute of Electrical and Micro Engineering, Ecole Polytechnique Federal de Lausanne, Route Cantonale, 1015, Lausanne, Switzerland
| | - Pawel Barmuta
- Department Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001, Leuven, Belgium
| | - Tomislav Markovic
- Department Electrical Engineering, KU Leuven, Kasteelpark Arenberg 10, 3001, Leuven, Belgium
- Faculty of Electrical Engineering and Computing, University of Zagreb, Unska 3, 10000, Zagreb, Croatia
| | - Rahul Yadav
- imec, Kapeldreef 75, 3001, Leuven, Belgium
- imec OnePlanet Research Center, Bronland 10, 6708 WE, Wageningen, The Netherlands
| | | | - Ilja Ocket
- imec, Kapeldreef 75, 3001, Leuven, Belgium
| | | | - Liesbet Lagae
- imec, Kapeldreef 75, 3001, Leuven, Belgium
- Department Physics and Astronomy, KU Leuven, Celestijnenlaan 200d, 3001, Leuven, Belgium
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Suzuki M, Kawai S, Shee CF, Yamada R, Uchida S, Yasukawa T. Development of a simultaneous electrorotation device with microwells for monitoring the rotation rates of multiple single cells upon chemical stimulation. LAB ON A CHIP 2023; 23:692-701. [PMID: 36355051 DOI: 10.1039/d2lc00627h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Here, we described a unique simultaneous electrorotation (ROT) device for monitoring the rotation rate of Jurkat cells via chemical stimulation without fluorescent labeling and an algorithm for estimating cell rotation rates. The device comprised two pairs of interdigitated array electrodes that were stacked orthogonally through a 20 μm-thick insulating layer with rectangular microwells. Four microelectrodes (two were patterned on the bottom of the microwells and the other two on the insulating layer) were arranged on each side of the rectangular microwells. The cells, which were trapped in the microwells, underwent ROT when AC voltages were applied to the four microelectrodes to generate a rotating electric field. These microwells maintained the cells even in fluid flows. Thereafter, the ROT rates of the trapped cells were estimated and monitored during the stimulation. We demonstrated the feasibility of estimating the chemical efficiency of cells by monitoring the ROT rates of the cells. After introducing a Jurkat cell suspension into the device, the cells were subjected to ROT by applying an AC signal. Further, the rotating cells were chemically stimulated by adding an ionomycin (a calcium ionophore)-containing aliquot. The ROT rate of the ionomycin-stimulated cells decreased gradually to 90% of the initial rate after 30 s. The ROT rate was reduced by an increase in membrane capacitance. Thus, our device enabled the simultaneous chemical stimulation-induced monitoring of the alterations in the membrane capacitances of many cells without fluorescent labeling.
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Affiliation(s)
- Masato Suzuki
- Graduate School of Science, University of Hyogo, Hyogo, Japan.
- Advanced Medical Engineering Research Institute, University of Hyogo, Hyogo, Japan
| | - Shikiho Kawai
- Graduate School of Science, University of Hyogo, Hyogo, Japan.
| | - Chean Fei Shee
- Department of Advanced Information Technology, Kyushu University, Fukuoka, Japan
| | - Ryoga Yamada
- Graduate School of Science, University of Hyogo, Hyogo, Japan.
| | - Seiichi Uchida
- Department of Advanced Information Technology, Kyushu University, Fukuoka, Japan
| | - Tomoyuki Yasukawa
- Graduate School of Science, University of Hyogo, Hyogo, Japan.
- Advanced Medical Engineering Research Institute, University of Hyogo, Hyogo, Japan
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3
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Brosch PK, Korsa T, Taban D, Eiring P, Hildebrand S, Neubauer J, Zimmermann H, Sauer M, Shirakashi R, Djuzenova CS, Sisario D, Sukhorukov VL. Glucose and Inositol Transporters, SLC5A1 and SLC5A3, in Glioblastoma Cell Migration. Cancers (Basel) 2022; 14:5794. [PMID: 36497276 PMCID: PMC9738886 DOI: 10.3390/cancers14235794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/04/2022] [Accepted: 11/20/2022] [Indexed: 11/27/2022] Open
Abstract
(1) Background: The recurrence of glioblastoma multiforme (GBM) is mainly due to invasion of the surrounding brain tissue, where organic solutes, including glucose and inositol, are abundant. Invasive cell migration has been linked to the aberrant expression of transmembrane solute-linked carriers (SLC). Here, we explore the role of glucose (SLC5A1) and inositol transporters (SLC5A3) in GBM cell migration. (2) Methods: Using immunofluorescence microscopy, we visualized the subcellular localization of SLC5A1 and SLC5A3 in two highly motile human GBM cell lines. We also employed wound-healing assays to examine the effect of SLC inhibition on GBM cell migration and examined the chemotactic potential of inositol. (3) Results: While GBM cell migration was significantly increased by extracellular inositol and glucose, it was strongly impaired by SLC transporter inhibition. In the GBM cell monolayers, both SLCs were exclusively detected in the migrating cells at the monolayer edge. In single GBM cells, both transporters were primarily localized at the leading edge of the lamellipodium. Interestingly, in GBM cells migrating via blebbing, SLC5A1 and SLC5A3 were predominantly detected in nascent and mature blebs, respectively. (4) Conclusion: We provide several lines of evidence for the involvement of SLC5A1 and SLC5A3 in GBM cell migration, thereby complementing the migration-associated transportome. Our findings suggest that SLC inhibition is a promising approach to GBM treatment.
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Affiliation(s)
- Philippa K. Brosch
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Tessa Korsa
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
- Fraunhofer Institute for Biomedical Engineering (IBMT), 66280 Sulzbach, Germany
| | - Danush Taban
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Patrick Eiring
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Sascha Hildebrand
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Julia Neubauer
- Fraunhofer Institute for Biomedical Engineering (IBMT), 66280 Sulzbach, Germany
| | - Heiko Zimmermann
- Fraunhofer Institute for Biomedical Engineering (IBMT), 66280 Sulzbach, Germany
- Department of Molecular and Cellular Biotechnology, Saarland University, 66123 Saarbrücken, Germany
- Faculty of Marine Science, Universidad Católica del Norte, Coquimbo 1281, Chile
| | - Markus Sauer
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Ryo Shirakashi
- Institute of Industrial Science, The University of Tokyo, Tokyo 153-8505, Japan
| | - Cholpon S. Djuzenova
- Department of Radiation Oncology, University Hospital of Würzburg, 97080 Würzburg, Germany
| | - Dmitri Sisario
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Vladimir L. Sukhorukov
- Department of Biotechnology & Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
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4
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Theoretical analysis for the fluctuation in the electric parameters of the electroporated cells before and during the electrofusion. Med Biol Eng Comput 2022; 60:3585-3600. [DOI: 10.1007/s11517-022-02683-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 09/27/2022] [Indexed: 11/05/2022]
Abstract
AbstractAn electric pulse with a sufficient amplitude can lead to electroporation of intracellular organelles. Also, the electric field can lead to electrofusion of the neighboring cells. In this paper, a finite element mathematical model was used to simulate the distribution, radius, and density of the pores. We simulated a mathematical model of the two neighbor cells to analyze the fluctuation in the electroporation parameters before the electrofusion under the ultra-shorted electric field pulse (i.e., impulse signal) for each cell separately and after the electrofusion under the ultra-shorted pulse. The analysis of the temporal and spatial distribution can lead to improving the mathematical models that are used to analyze both electroporation and electrofusion. The study combines the advantages of the nanosecond pulse to avoid the effect of the cell size on the electrofusion and the large-pore radius at the contact point between the cells.
Graphical abstract
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5
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Wu M, Ke Q, Bi J, Li X, Huang S, Liu Z, Ge L. Substantially Improved Electrofusion Efficiency of Hybridoma Cells: Based on the Combination of Nanosecond and Microsecond Pulses. Bioengineering (Basel) 2022; 9:bioengineering9090450. [PMID: 36134996 PMCID: PMC9495357 DOI: 10.3390/bioengineering9090450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/04/2022] [Accepted: 09/05/2022] [Indexed: 11/26/2022] Open
Abstract
As the initial antibody technology, the preparation of hybridoma cells has been widely used in discovering antibody drugs and is still in use. Various antibody drugs obtained through this technology have been approved for treating human diseases. However, the key to producing hybridoma cells is efficient cell fusion. High-voltage microsecond pulsed electric fields (μsHVPEFs) are currently one of the most common methods used for cell electrofusion. Nevertheless, the membrane potential induced by the external microsecond pulse is proportional to the diameter of the cell, making it difficult to fuse cells of different sizes. Although nanosecond pulsed electric fields (nsPEFs) can achieve the fusion of cells of different sizes, due to the limitation of pore size, deoxyribonucleic acid (DNA) cannot efficiently pass through the cell pores produced by nsPEFs. This directly causes the significant loss of the target gene and reduces the proportion of positive cells after fusion. To achieve an electric field environment independent of cell size and enable efficient cell fusion, we propose a combination of nanosecond pulsed electric fields and low-voltage microsecond pulsed electric fields (ns/μsLVPEFs) to balance the advantages and disadvantages of the two techniques. The results of fluorescence experiments and hybridoma culture experiments showed that after lymphocytes and myeloma cells were stimulated by a pulse (ns/μsLVPEF, μsHVPEF, and control), compared with μsHVPEF, applying ns/μsLVPEF at the same energy could increase the cell fusion efficiency by 1.5–3.0 times. Thus far, we have combined nanosecond and microsecond pulses and provided a practical solution that can significantly increase cell fusion efficiency. This efficient cell fusion method may contribute to the further development of hybridoma technology in electrofusion.
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Affiliation(s)
- Meng Wu
- College of Veterinary Medicine, Hunan Agricultural University, Changsha 410128, China
- Chongqing Academy of Animal Sciences, Chongqing 402460, China
| | - Qiang Ke
- Nanjing Research Institute of Electronics Technology, Nanjing 210039, China
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing 400044, China
- School of Nuclear Engineering, Purdue University, West Lafayette, IN 47906, USA
- Correspondence: (Q.K.); (Z.L.); (L.G.)
| | - Jinhao Bi
- College of Veterinary Medicine, Jilin Agricultural University, Changchun 130118, China
- School of Life Sciences, Westlake University, Hangzhou 310024, China
| | - Xinhao Li
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing 400044, China
| | - Shuheng Huang
- College of Bioengineering, Chongqing University, Chongqing 400044, China
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1A8, Canada
| | - Zuohua Liu
- Chongqing Academy of Animal Sciences, Chongqing 402460, China
- Correspondence: (Q.K.); (Z.L.); (L.G.)
| | - Liangpeng Ge
- Chongqing Academy of Animal Sciences, Chongqing 402460, China
- Correspondence: (Q.K.); (Z.L.); (L.G.)
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6
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Jiang M, Wang X, Zhao X, Teng Y, Chen J, Wang J, Yue W. Classification of tumor subtypes leveraging constriction-channel based impedance flow cytometry and optical imaging. Cytometry A 2021; 99:1114-1122. [PMID: 33909347 DOI: 10.1002/cyto.a.24358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/29/2021] [Indexed: 11/06/2022]
Abstract
As label-free biomarkers, electrical properties of single cells have been widely used for cell-type classification and cell-status evaluation. However, as intrinsic bioelectrical markers, previously reported membrane capacitance and cytoplasmic resistance (e.g., specific membrane capacitance Cspecific membrane and cytoplasmic conductivity σcytoplasm ) of tumor subtypes were derived from tens of single cells, lacking statistical significance due to low cell numbers. In this study, tumor subtypes were constructed based on phenotype (treatment with 4-methylumbelliferone) or genotype (knockdown of ROCK1) modifications and then aspirated through a constriction-channel based impedance flow cytometry to characterize single-cell Cspecific membrane and σcytoplasm . Thousands of single tumor cells with phenotype modifications were measured, resulting in significant differences in 1.64 ± 0.43 μF/cm2 vs. 1.55 ± 0.47 μF/cm2 of Cspecific membrane and 0.96 ± 0.37 S/m vs. 1.24 ± 0.47 S/m of σcytoplasm for 95C cells (792 cells of 95C-control vs. 1529 cells of 95C-pheno-mod); 2.56 ± 0.88 μF/cm2 vs. 2.33 ± 0.56 μF/cm2 of Cspecific membrane and 0.83 ± 0.18 S/m vs. 0.93 ± 0.25 S/m of σcytoplasm for H1299 cells (962 cells of H1299-control vs. 637 cells of H1299-pheno-mod). Furthermore, thousands of single tumor cells with genotype modifications were measured, resulting in significant differences in 3.82 ± 0.92 vs. 3.18 ± 0.47 μF/cm2 of Cspecific membrane and 0.47 ± 0.05 vs. 0.52 ± 0.05 S/m of σcytoplasm (1100 cells of A549-control vs. 1100 cells of A549-geno-mod). These results indicate that as intrinsic bioelectrical markers, specific membrane capacitance and cytoplasmic conductivity can be used to classify tumor subtypes.
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Affiliation(s)
- Mei Jiang
- Central Laboratory, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Xiaojie Wang
- Department of Human Reproductive Medicine, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Xiaoting Zhao
- Central Laboratory, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Yu Teng
- Central Laboratory, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Jian Chen
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China.,School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Junbo Wang
- State Key Laboratory of Transducer Technology, Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing, China.,School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Wentao Yue
- Central Laboratory, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
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7
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Fajrial AK, Liu K, Gao Y, Gu J, Lakerveld R, Ding X. Characterization of Single-Cell Osmotic Swelling Dynamics for New Physical Biomarkers. Anal Chem 2021; 93:1317-1325. [PMID: 33253534 DOI: 10.1021/acs.analchem.0c02289] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Characterization of cell physical biomarkers is vital to understand cell properties and applicable for disease diagnostics. Current methods used to analyze physical phenotypes involve external forces to deform the cells. Alternatively, internal tension forces via osmotic swelling can also deform the cells. However, an established assumption contends that the forces generated during hypotonic swelling concentrated on the plasma membrane are incapable of assessing the physical properties of nucleated cells. Here, we utilized an osmotic swelling approach to characterize different types of nucleated cells. Using a microfluidic device for cell trapping arrays with truncated hanging micropillars (CellHangars), we isolated single cells and evaluated the swelling dynamics during the hypotonic challenge at 1 s time resolution. We demonstrated that cells with different mechanical phenotypes showed unique swelling dynamics signature. Different types of cells can be classified with an accuracy of up to ∼99%. We also showed that swelling dynamics can detect cellular mechanical property changes due to cytoskeleton disruption. Considering its simplicity, swelling dynamics offers an invaluable label-free physical biomarker for cells with potential applications in both biological studies and clinical practice.
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Affiliation(s)
- Apresio K Fajrial
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Kun Liu
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Yu Gao
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States
| | - Junhao Gu
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Richard Lakerveld
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Xiaoyun Ding
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, 1111 Engineering Drive, UCB 427, Boulder, Colorado 80309, United States.,Biomedical Engineering Program, University of Colorado Boulder, Boulder, Colorado 80309, United States
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8
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Božič B, Zemljič Jokhadar Š, Kristanc L, Gomišček G. Cell Volume Changes and Membrane Ruptures Induced by Hypotonic Electrolyte and Sugar Solutions. Front Physiol 2020; 11:582781. [PMID: 33364974 PMCID: PMC7750460 DOI: 10.3389/fphys.2020.582781] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 11/06/2020] [Indexed: 01/09/2023] Open
Abstract
The cell volume changes induced by hypotonic electrolyte and sucrose solutions were studied in Chinese-hamster-ovary epithelial cells. The effects in the solutions with osmolarities between 32 and 315 mosM/L and distilled water were analyzed using bright-field and fluorescence confocal microscopy. The changes of the cell volume, accompanied by the detachment of cells, the formation of blebs, and the occurrence of almost spherical vesicle-like cells (“cell-vesicles”), showed significant differences in the long-time responses of the cells in the electrolyte solutions compared with the sucrose-containing solutions. A theoretical model based on different permeabilities of ions and sucrose molecules and on the action of Na+/K+-ATPase pumps is applied. It is consistent with the observed temporal behavior of the cells’ volume and the occurrence of tension-induced membrane ruptures and explains lower long-time responses of the cells in the sucrose solutions.
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Affiliation(s)
- Bojan Božič
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Špela Zemljič Jokhadar
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
| | - Luka Kristanc
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Gregor Gomišček
- Institute of Biophysics, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.,Faculty of Health Sciences, University of Ljubljana, Ljubljana, Slovenia
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9
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Liang W, Yang X, Wang J, Wang Y, Yang W, Liu L. Determination of Dielectric Properties of Cells using AC Electrokinetic-based Microfluidic Platform: A Review of Recent Advances. MICROMACHINES 2020; 11:E513. [PMID: 32438680 PMCID: PMC7281274 DOI: 10.3390/mi11050513] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/16/2020] [Accepted: 05/18/2020] [Indexed: 12/18/2022]
Abstract
Cell dielectric properties, a type of intrinsic property of cells, can be used as electrophysiological biomarkers that offer a label-free way to characterize cell phenotypes and states, purify clinical samples, and identify target cancer cells. Here, we present a review of the determination of cell dielectric properties using alternating current (AC) electrokinetic-based microfluidic mechanisms, including electro-rotation (ROT) and dielectrophoresis (DEP). The review covers theoretically how ROT and DEP work to extract cell dielectric properties. We also dive into the details of differently structured ROT chips, followed by a discussion on the determination of cell dielectric properties and the use of these properties in bio-related applications. Additionally, the review offers a look at the future challenges facing the AC electrokinetic-based microfluidic platform in terms of acquiring cell dielectric parameters. Our conclusion is that this platform will bring biomedical and bioengineering sciences to the next level and ultimately achieve the shift from lab-oriented research to real-world applications.
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Affiliation(s)
- Wenfeng Liang
- School of Mechanical Engineering, Shenyang Jianzhu University, Shenyang 110168, China; (X.Y.); (J.W.)
| | - Xieliu Yang
- School of Mechanical Engineering, Shenyang Jianzhu University, Shenyang 110168, China; (X.Y.); (J.W.)
| | - Junhai Wang
- School of Mechanical Engineering, Shenyang Jianzhu University, Shenyang 110168, China; (X.Y.); (J.W.)
| | - Yuechao Wang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China;
| | - Wenguang Yang
- School of Electromechanical and Automotive Engineering, Yantai University, Yantai 264005, China;
| | - Lianqing Liu
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China;
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10
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Ten-Second Electrophysiology: Evaluation of the 3DEP Platform for high-speed, high-accuracy cell analysis. Sci Rep 2019; 9:19153. [PMID: 31844107 PMCID: PMC6915758 DOI: 10.1038/s41598-019-55579-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/18/2019] [Indexed: 01/08/2023] Open
Abstract
Electrical correlates of the physiological state of a cell, such as membrane conductance and capacitance, as well as cytoplasm conductivity, contain vital information about cellular function, ion transport across the membrane, and propagation of electrical signals. They are, however, difficult to measure; gold-standard techniques are typically unable to measure more than a few cells per day, making widespread adoption difficult and limiting statistical reproducibility. We have developed a dielectrophoretic platform using a disposable 3D electrode geometry that accurately (r2 > 0.99) measures mean electrical properties of populations of ~20,000 cells, by taking parallel ensemble measurements of cells at 20 frequencies up to 45 MHz, in (typically) ten seconds. This allows acquisition of ultra-high-resolution (100-point) DEP spectra in under two minutes. Data acquired from a wide range of cells – from platelets to large cardiac cells - benchmark well with patch-clamp-data. These advantages are collectively demonstrated in a longitudinal (same-animal) study of rapidly-changing phenomena such as ultradian (2–3 hour) rhythmicity in whole blood samples of the common vole (Microtus arvalis), taken from 10 µl tail-nick blood samples and avoiding sacrifice of the animal that is typically required in these studies.
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11
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Uchida T, Furukawa M, Kikawada T, Yamazaki K, Gohara K. Trehalose uptake and dehydration effects on the cryoprotection of CHO–K1 cells expressing TRET1. Cryobiology 2019; 90:30-40. [DOI: 10.1016/j.cryobiol.2019.09.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 09/02/2019] [Accepted: 09/03/2019] [Indexed: 10/26/2022]
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12
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Ren D, Chui CO. Feasibility of Tracking Multiple Single-Cell Properties with Impedance Spectroscopy. ACS Sens 2018; 3:1005-1015. [PMID: 29737153 DOI: 10.1021/acssensors.8b00152] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electric cell-substrate impedance sensing (ECIS) has been instrumental in tracking collective behavior of confluent cell layers for decades. Toward probing cellular heterogeneity in a population, the single-cell version of ECIS has also been explored, yet its intrinsic capability and limitation remain unclear. In this work, we argue for the fundamental feasibility of impedance spectroscopy to track changes of multiple cellular properties using a noninvasive single-cell approach. While changing individual properties is experimentally prohibitive, we take a simulation approach instead and mimic the corresponding changes using a 3D computational model. From the resultant impedance spectra, we identify the spectroscopic signature characteristic to each property considered herein. Since multiple properties change concurrently in practice, the respective signatures often overlap spectroscopically and become hidden. We further attempt to deconvolve such spectra and reveal the underlying property changes. This work provides the theoretical foundation to inspire experimental validation and adoption of ECIS for multiproperty single-cell measurements.
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13
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Li C, Ke Q, Yao C, Mi Y, Liu H, Lv Y, Yao C. Cell electrofusion based on nanosecond/microsecond pulsed electric fields. PLoS One 2018; 13:e0197167. [PMID: 29795594 PMCID: PMC5967737 DOI: 10.1371/journal.pone.0197167] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 04/27/2018] [Indexed: 11/19/2022] Open
Abstract
Traditionally, microsecond pulsed electric field was widely used in cell electrofusion technology. However, it was difficult to fuse the cells with different sizes. Because the effect of electroporation based on microsecond pulses was greatly influenced by cell sizes. It had been reported that the differences between cell sizes can be ignored when cells were exposed to nanosecond pulses. However, pores induced by those short nanosecond pulses tended to be very small (0.9 nm) and the pores were more easy to recover. In this work, a finite element method was used to simulate the distribution, radius and density of the pores. The innovative idea of "cell electrofusion based on nanosecond/microsecond pulses" was proposed in order to combine the advantages of nanosecond pulses and microsecond pulses. The model consisted of two contact cells with different sizes. Three kinds of pulsed electric fields were made up of two 100-ns, 10-kV/cm pulses; two 10-μs, 1-kV/cm pulses; and a sequence of a 100-ns, 10-kV/cm pulse, followed by a 10-μs, 1-kV/cm pulse. Some obvious advantageous can be found when nanosecond/microsecond pulses were considered. The pore radius was large enough (70nm) and density was high (5×1013m-2) in the cell junction area. Moreover, pores in the non-contact area of the cell membrane were small (1-10 nm) and sparse (109-1012m-2). Areas where the transmembrane voltage was higher than 1V were only concentrated in the cell junction. The transmembrane voltage of other areas were at most 0.6V when we tested the rest of the cell membrane. Cell fusion efficiency can be improved remarkably because electroporation was concentrated in the cell contact area.
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Affiliation(s)
- Chengxiang Li
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Qiang Ke
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Chenguo Yao
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Yan Mi
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Hongmei Liu
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Yanpeng Lv
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Cheng Yao
- The State Key Laboratory of Power Transmission Equipment & System Security and New Technology, School of Electrical Engineering, Chongqing University, Chongqing, China
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Eguzozie K, Mavumengwana V, Nkosi D, Kayitesi E, Nnabuo-Eguzozie EC. Bioaccumulation and Quantitative Variations of Microcystins in the Swartspruit River, South Africa. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2016; 71:286-296. [PMID: 26936473 DOI: 10.1007/s00244-016-0269-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 02/06/2016] [Indexed: 06/05/2023]
Abstract
The bioaccumulation and quantitative variations of cyanobacterial peptide hepatotoxin intracellular microcystin in floating scums of cyanobacterium microcystis flos aquae collected from predetermined sampling sites in the Swartspruit River was investigated. Three distinct MCs variants (MC-YR, MC-LR, and MC-RR) were isolated, identified, and quantified. Additionally, two minor microcystin congeners (MC-(H4) YR), (D-Asp(3), Dha(7))MC-RR) also were identified but were not quantified. Quantitative analysis was achieved using peak areas substituted on linear regression equations: Y = 10085x - 19698 (R (2) = 0.9998), Y = 201387x + 20328 (R (2) = 0.9929), Y = 2506x + 15659 (R (2) = 0.9999), and 9859x + 208694 (R (2) = 0.9929) of standard curves for 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 μg/mL MC-LR, MC-RR, MC-YR respectively. Variant dominance followed the order MC-LR > MC-RR > MC-YR across the sampling sites. Analysis of maximum and minimum concentrations of quantified MCs variants showed 270.7, 14.10 (µg/g), 141.5, 1.43 (µg/g), and 72.28, 0.15 (µg/g) for MC-LR, MC-RR, and MC-YR, respectively. This implies there was quantitative variations of microcystin congeners across the sampled sites. Significant differences between means were assessed by an analysis of variance with P < 0.05 being considered significant. Results showed that there were no significant difference between mean MCs concentrations across the sampling periods (P > 0.05) and significant difference between mean MCs concentrations across sampling sites (P < 0.05).
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Affiliation(s)
- Kennedy Eguzozie
- Department of Biotechnology and Food Technology, University of Johannesburg, Johannesburg, South Africa.
| | - Vuyo Mavumengwana
- Department of Biotechnology and Food Technology, University of Johannesburg, Johannesburg, South Africa
| | - Duduzile Nkosi
- Department of Applied Chemistry, Faculty of Science, University of Johannesburg, Johannesburg, South Africa
| | - Eugenie Kayitesi
- Department of Biotechnology and Food Technology, University of Johannesburg, Johannesburg, South Africa
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Andronic J, Shirakashi R, Pickel SU, Westerling KM, Klein T, Holm T, Sauer M, Sukhorukov VL. Hypotonic activation of the myo-inositol transporter SLC5A3 in HEK293 cells probed by cell volumetry, confocal and super-resolution microscopy. PLoS One 2015; 10:e0119990. [PMID: 25756525 PMCID: PMC4355067 DOI: 10.1371/journal.pone.0119990] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 01/21/2015] [Indexed: 11/19/2022] Open
Abstract
Swelling-activated pathways for myo-inositol, one of the most abundant organic osmolytes in mammalian cells, have not yet been identified. The present study explores the SLC5A3 protein as a possible transporter of myo-inositol in hyponically swollen HEK293 cells. To address this issue, we examined the relationship between the hypotonicity-induced changes in plasma membrane permeability to myo-inositol Pino [m/s] and expression/localization of SLC5A3. Pino values were determined by cell volumetry over a wide tonicity range (100–275 mOsm) in myo-inositol-substituted solutions. While being negligible under mild hypotonicity (200–275 mOsm), Pino grew rapidly at osmolalities below 200 mOsm to reach a maximum of ∼3 nm/s at 100–125 mOsm, as indicated by fast cell swelling due to myo-inositol influx. The increase in Pino resulted most likely from the hypotonicity-mediated incorporation of cytosolic SLC5A3 into the plasma membrane, as revealed by confocal fluorescence microscopy of cells expressing EGFP-tagged SLC5A3 and super-resolution imaging of immunostained SLC5A3 by direct stochastic optical reconstruction microscopy (dSTORM). dSTORM in hypotonic cells revealed a surface density of membrane-associated SLC5A3 proteins of 200–2000 localizations/μm2. Assuming SLC5A3 to be the major path for myo-inositol, a turnover rate of 80–800 myo-inositol molecules per second for a single transporter protein was estimated from combined volumetric and dSTORM data. Hypotonic stress also caused a significant upregulation of SLC5A3 gene expression as detected by semiquantitative RT-PCR and Western blot analysis. In summary, our data provide first evidence for swelling-mediated activation of SLC5A3 thus suggesting a functional role of this transporter in hypotonic volume regulation of mammalian cells.
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Affiliation(s)
- Joseph Andronic
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Ryo Shirakashi
- Institute of Industrial Science, The University of Tokyo, Tokyo, Japan
| | - Simone U. Pickel
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Katherine M. Westerling
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Teresa Klein
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Thorge Holm
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
| | - Vladimir L. Sukhorukov
- Department of Biotechnology and Biophysics, University of Würzburg, Biozentrum, Am Hubland, Würzburg, Germany
- * E-mail:
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Memmel S, Sukhorukov VL, Höring M, Westerling K, Fiedler V, Katzer A, Krohne G, Flentje M, Djuzenova CS. Cell surface area and membrane folding in glioblastoma cell lines differing in PTEN and p53 status. PLoS One 2014; 9:e87052. [PMID: 24498019 PMCID: PMC3909012 DOI: 10.1371/journal.pone.0087052] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Accepted: 12/17/2013] [Indexed: 01/22/2023] Open
Abstract
Glioblastoma multiforme (GBM) is characterized by rapid growth, invasion and resistance to chemo−/radiotherapy. The complex cell surface morphology with abundant membrane folds, microvilli, filopodia and other membrane extensions is believed to contribute to the highly invasive behavior and therapy resistance of GBM cells. The present study addresses the mechanisms leading to the excessive cell membrane area in five GBM lines differing in mutational status for PTEN and p53. In addition to scanning electron microscopy (SEM), the membrane area and folding were quantified by dielectric measurements of membrane capacitance using the single-cell electrorotation (ROT) technique. The osmotic stability and volume regulation of GBM cells were analyzed by video microscopy. The expression of PTEN, p53, mTOR and several other marker proteins involved in cell growth and membrane synthesis were examined by Western blotting. The combined SEM, ROT and osmotic data provided independent lines of evidence for a large variability in membrane area and folding among tested GBM lines. Thus, DK-MG cells (wild type p53 and wild type PTEN) exhibited the lowest degree of membrane folding, probed by the area-specific capacitance Cm = 1.9 µF/cm2. In contrast, cell lines carrying mutations in both p53 and PTEN (U373-MG and SNB19) showed the highest Cm values of 3.7–4.0 µF/cm2, which corroborate well with their heavily villated cell surface revealed by SEM. Since PTEN and p53 are well-known inhibitors of mTOR, the increased membrane area/folding in mutant GBM lines may be related to the enhanced protein and lipid synthesis due to a deregulation of the mTOR-dependent downstream signaling pathway. Given that membrane folds and extensions are implicated in tumor cell motility and metastasis, the dielectric approach presented here provides a rapid and simple tool for screening the biophysical cell properties in studies on targeting chemo- or radiotherapeutically the migration and invasion of GBM and other tumor types.
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Affiliation(s)
- Simon Memmel
- Lehrstuhl für Biotechnologie und Biophysik, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Vladimir L. Sukhorukov
- Lehrstuhl für Biotechnologie und Biophysik, Universität Würzburg, Am Hubland, Würzburg, Germany
- * E-mail: (VLS); (CSD)
| | - Marcus Höring
- Lehrstuhl für Biotechnologie und Biophysik, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Katherine Westerling
- Lehrstuhl für Biotechnologie und Biophysik, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Vanessa Fiedler
- Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
| | - Astrid Katzer
- Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
| | - Georg Krohne
- Elektronenmikroskopie, Biozentrum, Universität Würzburg, Am Hubland, Würzburg, Germany
| | - Michael Flentje
- Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
| | - Cholpon S. Djuzenova
- Department of Radiation Oncology, University Hospital Würzburg, Würzburg, Germany
- * E-mail: (VLS); (CSD)
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17
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Cell electrofusion using nanosecond electric pulses. Sci Rep 2013; 3:3382. [PMID: 24287643 PMCID: PMC3843160 DOI: 10.1038/srep03382] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 11/13/2013] [Indexed: 12/21/2022] Open
Abstract
Electrofusion is an efficient method for fusing cells using short-duration high-voltage electric pulses. However, electrofusion yields are very low when fusion partner cells differ considerably in their size, since the extent of electroporation (consequently membrane fusogenic state) with conventionally used microsecond pulses depends proportionally on the cell radius. We here propose a new and innovative approach to fuse cells with shorter, nanosecond (ns) pulses. Using numerical calculations we demonstrate that ns pulses can induce selective electroporation of the contact areas between cells (i.e. the target areas), regardless of the cell size. We then confirm experimentally on B16-F1 and CHO cell lines that electrofusion of cells with either equal or different size by using ns pulses is indeed feasible. Based on our results we expect that ns pulses can improve fusion yields in electrofusion of cells with different size, such as myeloma cells and B lymphocytes in hybridoma technology.
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18
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Ouyang M, Ki Cheung W, Liang W, Mai JD, Keung Liu W, Jung Li W. Inducing self-rotation of cells with natural and artificial melanin in a linearly polarized alternating current electric field. BIOMICROFLUIDICS 2013; 7:54112. [PMID: 24404075 PMCID: PMC3799643 DOI: 10.1063/1.4821169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 08/30/2013] [Indexed: 05/15/2023]
Abstract
The phenomenon of self-rotation observed in naturally and artificially pigmented cells under an applied linearly polarized alternating current (non-rotating) electrical field has been investigated. The repeatable and controllable rotation speeds of the cells were quantified and their dependence on dielectrophoretic parameters such as frequency, voltage, and waveform was studied. Moreover, the rotation behavior of the pigmented cells with different melanin content was compared to quantify the correlation between self-rotation and the presence of melanin. Most importantly, macrophages, which did not originally rotate in the applied non-rotating electric field, began to exhibit self-rotation that was very similar to that of the pigmented cells, after ingesting foreign particles (e.g., synthetic melanin or latex beads). We envision the discovery presented in this paper will enable the development of a rapid, non-intrusive, and automated process to obtain the electrical conductivities and permittivities of cellular membrane and cytoplasm in the near future.
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Affiliation(s)
- Mengxing Ouyang
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Wing Ki Cheung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, N. T., Hong Kong
| | - Wenfeng Liang
- State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China
| | - John D Mai
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong
| | - Wing Keung Liu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, N. T., Hong Kong
| | - Wen Jung Li
- Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon, Hong Kong ; State Key Laboratory of Robotics, Shenyang Institute of Automation, Chinese Academy of Sciences, Shenyang 110016, China
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19
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Pietuch A, Brückner BR, Janshoff A. Membrane tension homeostasis of epithelial cells through surface area regulation in response to osmotic stress. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012. [PMID: 23178740 DOI: 10.1016/j.bbamcr.2012.11.006] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Osmotic stress poses one of the most fundamental challenges to living cells. Particularly, the largely inextensible plasma membrane of eukaryotic cells easily ruptures under in-plane tension calling for sophisticated strategies to readily respond to osmotic stress. We describe how epithelial cells react and adapt mechanically to the exposure to hypotonic and hypertonic solutions in the context of a confluent monolayer. Site-specific indentation experiments in conjunction with tether pulling on individual cells have been carried out with an atomic force microscope to reveal spatio-temporal changes in membrane tension and surface area. We found that cells compensate for an increase in lateral tension due to hypoosmotic stress by sacrificing excess of membrane area stored in protrusions and invaginations such as microvilli and caveolae. At mild hypotonic conditions lateral tension increases partly compensated by surface are regulation, i.e. the cell sacrifices some of its membrane reservoirs. A loss of membrane-actin contacts occurs upon exposure to stronger hypotonic solutions giving rise to a drop in lateral tension. Tension release recovers on longer time scales by an increasing endocytosis, which efficiently removes excess membrane from the apical side to restore the initial pre-stress. Hypertonic solutions lead to shrinkage of cells and collapse of the apical membrane onto the cortex. Exposure to distilled water leads to stiffening of cells due to removal of excess surface area and tension increase due to elevated osmotic pressure across the plasma membrane.
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Affiliation(s)
- Anna Pietuch
- Institute of Physical Chemistry, Georg-August-University of Goettingen, Tammannstrasse 6, 37077 Goettingen, Germany.
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20
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Andronic J, Bobak N, Bittner S, Ehling P, Kleinschnitz C, Herrmann AM, Zimmermann H, Sauer M, Wiendl H, Budde T, Meuth SG, Sukhorukov VL. Identification of two-pore domain potassium channels as potent modulators of osmotic volume regulation in human T lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:699-707. [PMID: 23041580 DOI: 10.1016/j.bbamem.2012.09.028] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2012] [Revised: 09/21/2012] [Accepted: 09/27/2012] [Indexed: 11/17/2022]
Abstract
Many functions of T lymphocytes are closely related to cell volume homeostasis and regulation, which utilize a complex network of membrane channels for anions and cations. Among the various potassium channels, the voltage-gated K(V)1.3 is well known to contribute greatly to the osmoregulation and particularly to the potassium release during the regulatory volume decrease (RVD) of T cells faced with hypotonic environment. Here we address a putative role of the newly identified two-pore domain (K(2P)) channels in the RVD of human CD4(+) T lymphocytes, using a series of potent well known channel blockers. In the present study, the pharmacological profiles of RVD inhibition revealed K(2P)5.1 and K(2P)18.1 as the most important K(2P) channels involved in the RVD of both naïve and stimulated T cells. The impact of chemical inhibition of K(2P)5.1 and K(2P)18.1 on the RVD was comparable to that of K(V)1.3. K(2P)9.1 also notably contributed to the RVD of T cells but the extent of this contribution and its dependence on the activation status could not be unambiguously resolved. In summary, our data provide first evidence that the RVD-related potassium efflux from human T lymphocytes relies on K(2P) channels.
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Affiliation(s)
- Joseph Andronic
- University of Wuerzburg, Lehrstuhl für Biotechnologie und Biophysik, Biozentrum, Am Hubland, 97074 Wuerzburg, Germany
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21
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Dielectric Analysis and Multi-cell Electrofusion of the Yeast Pichia pastoris for Electrophysiological Studies. J Membr Biol 2012; 245:815-26. [DOI: 10.1007/s00232-012-9484-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 06/30/2012] [Indexed: 12/21/2022]
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Cell activation by CpG ODN leads to improved electrofusion in hybridoma production. J Immunol Methods 2011; 373:102-10. [PMID: 21878337 DOI: 10.1016/j.jim.2011.08.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 08/11/2011] [Accepted: 08/11/2011] [Indexed: 12/21/2022]
Abstract
Hybridoma formation is an indispensable step in the production of monoclonal antibodies. Obtaining highly efficient fusion of an antibody-producing cell to the myeloma cell to form the hybridoma is an important step in this process. The electrofusion method is superior to chemical fusion methods such as the polyethylene glycol (PEG) method due to its high fusion efficiency. However, this method requires cell activation prior to electrofusion, a process that is time-consuming and tends to cause cell death. In this study, we achieved much higher fusion efficiency by stimulating B cells with CpG oligodeoxynucleotide (CpG ODN) over shorter periods. Splenocytes were isolated from immunized mice and cultured in the presence of a CpG ODN for 1 or 2 days. This CpG ODN stimulation evokes about one order of magnitude higher fusion efficiency than other stimulators. CpG ODN stimulation not only increases the fusion efficiency but also the number of antibody-producing cells. This leads to a substantial increase in the number of positive clones obtained. This highly efficient fusion method was used to produce a functional antibody against Gaussia luciferase. This method was found to produce greater numbers of hybridomas and to enable direct screening for antibodies with functional characteristics such as inhibition of the luminescence activity of an antigen. We were able to establish a functional antibody against Gaussia luciferase after a single fusion experiment using our electrofusion method.
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23
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Bobak N, Bittner S, Andronic J, Hartmann S, Mühlpfordt F, Schneider-Hohendorf T, Wolf K, Schmelter C, Göbel K, Meuth P, Zimmermann H, Döring F, Wischmeyer E, Budde T, Wiendl H, Meuth SG, Sukhorukov VL. Volume regulation of murine T lymphocytes relies on voltage-dependent and two-pore domain potassium channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2036-44. [DOI: 10.1016/j.bbamem.2011.04.013] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 04/22/2011] [Accepted: 04/25/2011] [Indexed: 01/05/2023]
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Kiehl TR, Shen D, Khattak SF, Jian Li Z, Sharfstein ST. Observations of cell size dynamics under osmotic stress. Cytometry A 2011; 79:560-9. [PMID: 21656664 DOI: 10.1002/cyto.a.21076] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 01/03/2011] [Accepted: 04/11/2011] [Indexed: 11/11/2022]
Abstract
Cultured mammalian cells [e.g., murine hybridomas, Chinese hamster ovary (CHO) cells] used to produce therapeutic and diagnostic proteins often exhibit increased specific productivity under osmotic stress. This increase in specific productivity is accompanied by a number of physiological changes, including cell size variation. Investigating the cell size variation of hyperosmotically stressed cultures may reveal, in part, the basis for increased specific productivity as well as an understanding of some of the cellular defense responses that occur under hyperosmotic conditions. The regulation of cell volume is a critical function maintained in animal cells. Although these cells are highly permeable to water, they are significantly less permeable to ionic solutes. Appropriate cell-water content is actively maintained in these cells by regulation of ion and osmolyte balances. Transport appropriate to extracellular conditions, leading to accrual or release of these species, is activated in response to acute cell volume changes. Osmotically induced regulatory volume increases (RVI) and regulatory volume decreases (RVD) are known to occur under a variety of conditions. We observed the time evolution of size variation in populations of two CHO cell lines under hyperosmotic conditions. Observations were made using multiple instruments, multiple cell lines, and multiple cell culture conditions. Size variation of CHO A1 was gauged by flow cytometry using an LSRII® flow cytometer while CHO B0 cells were quantified using a Cedex® cell analyzer. Hyperosmotic stress had a dose-dependent effect on the regulatory control of cell volume. Stressed cultures of CHO cells grown in suspension exhibited a shift in mean cell diameter. This shift in mean was not due to a change in the whole population, but rather to the emergence of distinct subpopulations of cells with larger cell diameters than those in the bulk of the population.
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Affiliation(s)
- Thomas R Kiehl
- Multidisciplinary Science Program and Center for Biotechnology and Interdisciplinary Science, Rensselaer Polytechnic Institute, Troy, New York 12180, USA
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25
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Lange K. Fundamental role of microvilli in the main functions of differentiated cells: Outline of an universal regulating and signaling system at the cell periphery. J Cell Physiol 2010; 226:896-927. [PMID: 20607764 DOI: 10.1002/jcp.22302] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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26
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de la Rica R, Thompson S, Baldi A, Fernandez-Sanchez C, Drain CM, Matsui H. Label-free cancer cell detection with impedimetric transducers. Anal Chem 2010; 81:10167-71. [PMID: 19911810 DOI: 10.1021/ac9021049] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
While cancer is still an implacable disease, many cancers can be cured if they are diagnosed in an early stage. Recently, it was reported that the transformation from normal cells to cancer cells can change their mechanoelastic properties to become softer and more deformable. If some cancer cells are more deformable, then a progressive increase of the volume of softer cancer cells should be induced as an abrupt change in osmolarity is applied. On the basis of this hypothesis, we developed a sensor that can electronically monitor the volume increase of cancer cells under hyposmotic pressure. By this methodology, K:Molv NIH 3T3 cells, 786-O human kidney carcinoma cells, and MPSC-1 ovarian cancer cells were successfully detected within 30 min using on the order of 10 cells. These cancer cells could be detected with the same sensitivity even in the presence of a vast excess of the respective noncancerous cells [NIH 3T3 cells, human embryonic kidney (HEK) 293 cells, ovarian surface epithelial (OSE) cells]. Since the proposed impedimetric sensor could be useful for detecting cancer cells fast and reliably, it could be further implemented in the screening of large populations of tissue samples and the detection of circulating tumor cells for point-of-care applications.
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Affiliation(s)
- Roberto de la Rica
- Department of Chemistry and Biochemistry, Hunter College-CUNY, 695 Park Ave, New York, New York 10065, USA
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27
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Sukhorukov VL, Imes D, Woellhaf MW, Andronic J, Kiesel M, Shirakashi R, Zimmermann U, Zimmermann H. Pore size of swelling-activated channels for organic osmolytes in Jurkat lymphocytes, probed by differential polymer exclusion. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1841-50. [DOI: 10.1016/j.bbamem.2009.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Revised: 06/04/2009] [Accepted: 06/19/2009] [Indexed: 10/20/2022]
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28
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Cell size dynamics and viability of cells exposed to hypotonic treatment and electroporation for electrofusion optimization. Radiol Oncol 2009. [DOI: 10.2478/v10019-009-0017-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Spagnoli C, Beyder A, Besch S, Sachs F. Atomic force microscopy analysis of cell volume regulation. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 78:031916. [PMID: 18851074 PMCID: PMC2744968 DOI: 10.1103/physreve.78.031916] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Indexed: 05/10/2023]
Abstract
Cells swell in response a hypoosmotic challenge. By converting osmotic pressure to hydrostatic pressure at the cell membrane via van't Hoff's law, and converting that to tension via Laplace's law one predicts that the cell membrane should stretch and become stiff. We tested this prediction using the atomic force microscopy. During osmotic swelling cells did not become stiff and generally became softer. This result contradicts the assumption of the cell membrane as the constraining element in osmotic stress but is consistent with the cytoskeleton acting as a cross-linked gel. Models of the cells' response to osmotic stress must include energy terms for three-dimensional stresses.
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Affiliation(s)
- Chiara Spagnoli
- Dip. Scienze e tecnologie chimiche, Universita' di Roma "Tor Vergata", via della Ricerca Scientifica 1, 0133 Rome, Italy
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30
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Schade-Kampmann G, Huwiler A, Hebeisen M, Hessler T, Di Berardino M. On-chip non-invasive and label-free cell discrimination by impedance spectroscopy. Cell Prolif 2008; 41:830-40. [PMID: 18673370 DOI: 10.1111/j.1365-2184.2008.00548.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
OBJECTIVES Many flow-cytometric cell characterization methods require costly markers and colour reagents. We present here a novel device for cell discrimination based on impedance measurement of electrical cell properties in a microfluidic chip, without the need of extensive sample preparation steps and the requirement of labelling dyes. MATERIALS AND METHODS, RESULTS We demonstrate that in-flow single cell measurements in our microchip allow for discrimination of various cell line types, such as undifferentiated mouse fibroblasts 3T3-L1 and adipocytes on the one hand, or human monocytes and in vitro differentiated dendritic cells and macrophages on the other hand. In addition, viability and apoptosis analyses were carried out successfully for Jurkat cell models. Studies on several species, including bacteria or fungi, demonstrate not only the capability to enumerate these cells, but also show that even other microbiological life cycle phases can be visualized. CONCLUSIONS These results underline the potential of impedance spectroscopy flow cytometry as a valuable complement to other known cytometers and cell detection systems.
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Affiliation(s)
- G Schade-Kampmann
- Leister Process Technologies, Axetris Microsystems Division, Kägiswil, Switzerland
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31
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Davis DM, Sowinski S. Membrane nanotubes: dynamic long-distance connections between animal cells. Nat Rev Mol Cell Biol 2008; 9:431-6. [PMID: 18431401 DOI: 10.1038/nrm2399] [Citation(s) in RCA: 295] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Membrane nanotubes are transient long-distance connections between cells that can facilitate intercellular communication (for example, by trafficking vesicles or transmitting calcium-mediated signals), but they can also contribute to pathologies (for example, by directing the spread of viruses). Recent data have revealed considerable heterogeneity in their structures, processes of formation and functional properties, in part dependent on the cell types involved. Despite recent progress in this young research field, further research is sorely needed.
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Affiliation(s)
- Daniel M Davis
- Division of Cell and Molecular Biology, Sir Alexander Fleming Building, Imperial College, London, SW7 2AZ, UK.
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32
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Zimmermann D, Zhou A, Kiesel M, Feldbauer K, Terpitz U, Haase W, Schneider-Hohendorf T, Bamberg E, Sukhorukov VL. Effects on capacitance by overexpression of membrane proteins. Biochem Biophys Res Commun 2008; 369:1022-6. [PMID: 18331832 DOI: 10.1016/j.bbrc.2008.02.153] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2008] [Accepted: 02/26/2008] [Indexed: 11/20/2022]
Abstract
Functional Channelrhodopsin-2 (ChR2) overexpression of about 10(4)channels/mum(2) in the plasma membrane of HEK293 cells was studied by patch-clamp and freeze-fracture electron microscopy. Simultaneous electrorotation measurements revealed that ChR2 expression was accompanied by a marked increase of the area-specific membrane capacitance (C(m)). The C(m) increase apparently resulted partly from an enlargement of the size and/or number of microvilli. This is suggested by a relatively large C(m) of 1.15+/-0.08 microF/cm(2) in ChR2-expressing cells measured under isotonic conditions. This value was much higher than that of the control HEK293 cells (0.79+/-0.02 microF/cm(2)). However, even after complete loss of microvilli under strong hypoosmolar conditions (100 mOsm), the ChR2-expressing cells still exhibited a significantly larger C(m) (0.85+/-0.07 microF/cm(2)) as compared to non-expressing control cells (0.70+/-0.03 microF/cm(2)). Therefore, a second mechanism of capacitance increase may involve changes in the membrane permittivity and/or thickness due to the embedded ChR2 proteins.
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Affiliation(s)
- D Zimmermann
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, Max-von-Laue-Strasse 3, 60438 Frankfurt am Main, Germany
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33
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Zimmermann D, Kiesel M, Terpitz U, Zhou A, Reuss R, Kraus J, Schenk WA, Bamberg E, Sukhorukov VL. A combined patch-clamp and electrorotation study of the voltage- and frequency-dependent membrane capacitance caused by structurally dissimilar lipophilic anions. J Membr Biol 2008; 221:107-21. [PMID: 18197354 PMCID: PMC2755742 DOI: 10.1007/s00232-007-9090-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Accepted: 12/13/2007] [Indexed: 11/30/2022]
Abstract
Interactions of structurally dissimilar anionic compounds with the plasma membrane of HEK293 cells were analyzed by patch clamp and electrorotation. The combined approach provides complementary information on the lipophilicity, preferential affinity of the anions to the inner/outer membrane leaflet, adsorption depth and transmembrane mobility. The anionic species studied here included the well-known lipophilic anions dipicrylamine (DPA−), tetraphenylborate (TPB−) and [W2(CO)10(S2CH)]−, the putative lipophilic anion
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\begin{document}$$ {\text{B}}{\left( {{\text{CF}}_{3} } \right)}^{ - }_{4} $$\end{document} and three new heterocyclic W(CO)5 derivatives. All tested anions partitioned strongly into the cell membrane, as indicated by the capacitance increase in patch-clamped cells. The capacitance increment exhibited a bell-shaped dependence on membrane voltage. The midpoint potentials of the maximum capacitance increment were negative, indicating the exclusion of lipophilic anions from the outer membrane leaflet. The adsorption depth of the large organic anions DPA−, TPB− and \documentclass[12pt]{minimal}
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\begin{document}$$ {\text{B}}{\left( {{\text{CF}}_{3} } \right)}^{ - }_{4} $$\end{document} increased and that of W(CO)5 derivatives decreased with increasing concentration of mobile charges. In agreement with the patch-clamp data, electrorotation of cells treated with DPA− and W(CO)5 derivatives revealed a large dispersion of membrane capacitance in the kilohertz to megahertz range due to the translocation of mobile charges. In contrast, in the presence of TPB− and \documentclass[12pt]{minimal}
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\begin{document}$$ {\text{B}}{\left( {{\text{CF}}_{3} } \right)}^{ - }_{4} $$\end{document} no mobile charges could be detected by electrorotation, despite their strong membrane adsorption. Our data suggest that the presence of oxygen atoms in the outer molecular shell is an important factor for the fast translocation ability of lipophilic anions.
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Affiliation(s)
- D Zimmermann
- Department of Biophysical Chemistry, Max-Planck Institute of Biophysics, Max-von-Laue Strasse 3, D-60438, Frankfurt am Main, Germany
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Sukhorukov VL, Endter JM, Zimmermann D, Shirakashi R, Fehrmann S, Kiesel M, Reuss R, Becker D, Hedrich R, Bamberg E, Roitsch T, Zimmermann U. Mechanisms of electrically mediated cytosolic Ca2+ transients in aequorin-transformed tobacco cells. Biophys J 2007; 93:3324-37. [PMID: 17675352 PMCID: PMC2025648 DOI: 10.1529/biophysj.107.110783] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 07/10/2007] [Indexed: 11/18/2022] Open
Abstract
Cytosolic Ca(2+) changes induced by electric field pulses of 50-micros duration and 200-800 V/cm strength were monitored by measuring chemiluminescence in aequorin-transformed BY-2 tobacco cells. In Ca(2+)-substituted media, electropulsing led to a very fast initial increase of the cytosolic Ca(2+) concentration reaching a peak value within <100-200 ms. Peaking of [Ca(2+)](cyt) was followed by a biphasic decay due to removal of Ca(2+) (e.g., by binding and/or sequestration in the cytosol). The decay had fast and slow components, characterized by time constants of approximately 0.5 and 3-5 s, respectively. Experiments with various external Ca(2+) concentrations and conductivities showed that the fast decay arises from Ca(2+) fluxes through the plasmalemma, whereas the slow decay must be assigned to Ca(2+) fluxes through the tonoplast. The amplitude of the [Ca(2+)](cyt) transients increased with increasing field strength, whereas the time constants of the decay kinetics remained invariant. Breakdown of the plasmalemma was achieved at a critical field strength of approximately 450 V/cm, whereas breakdown of the tonoplast required approximately 580 V/cm. The above findings could be explained by the transient potential profiles generated across the two membranes in response to an exponentially decaying field pulse. The dielectric data required for calculation of the tonoplast and plasmalemma potentials were derived from electrorotation experiments on isolated vacuolated and evacuolated BY-2 protoplasts. The electrorotation response of vacuolated protoplasts could be described in terms of a three-shell model (i.e., by assuming that the capacitances of tonoplast and plasmalemma are arranged in series). Among other things, the theoretical analysis together with the experimental data show that genetic manipulations of plant cells by electrotransfection or electrofusion must be performed in low-conductivity media to minimize release of vacuolar Ca(2+) and presumably other vacuolar ingredients.
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Affiliation(s)
- V L Sukhorukov
- Lehrstuhl für Biotechnologie, Julius-von-Sachs-Institut für Biowissenschaften, Universität Würzburg, Würzburg, Germany
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35
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Garner AL, Chen G, Chen N, Sridhara V, Kolb JF, Swanson RJ, Beebe SJ, Joshi RP, Schoenbach KH. Ultrashort electric pulse induced changes in cellular dielectric properties. Biochem Biophys Res Commun 2007; 362:139-144. [PMID: 17706595 DOI: 10.1016/j.bbrc.2007.07.159] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Accepted: 07/31/2007] [Indexed: 11/22/2022]
Abstract
The interaction of nanosecond duration pulsed electric fields (nsPEFs) with biological cells, and the models describing this behavior, depend critically on the electrical properties of the cells being pulsed. Here, we used time domain dielectric spectroscopy to measure the dielectric properties of Jurkat cells, a malignant human T-cell line, before and after exposure to five 10ns, 150kV/cm electrical pulses. The cytoplasm and nucleoplasm conductivities decreased dramatically following pulsing, corresponding to previously observed rises in cell suspension conductivity. This suggests that electropermeabilization occurred, resulting in ion transport from the cell's interior to the exterior. A delayed decrease in cell membrane conductivity after the nsPEFs possibly suggests long-term ion channel damage or use dependence due to repeated membrane charging and discharging. This data could be used in models describing the phenomena at work.
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Affiliation(s)
- Allen L Garner
- Bioelectromagnetism Laboratory, Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109, USA; Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA.
| | - George Chen
- School of Electronics and Computer Science, University of Southampton, Southampton So17 1bj, UK
| | - Nianyong Chen
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA
| | - Viswanadham Sridhara
- Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529, USA
| | - Juergen F Kolb
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA; Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529, USA
| | - R James Swanson
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA; Department of Biological Sciences, Old Dominion University, Norfolk, VA 23529, USA
| | - Stephen J Beebe
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA; Department of Physiological Sciences, Eastern Virginia Medical School, Norfolk, VA 23510, USA
| | - Ravindra P Joshi
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA; Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529, USA
| | - Karl H Schoenbach
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA 23510, USA; Department of Electrical and Computer Engineering, Old Dominion University, Norfolk, VA 23529, USA.
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Abstract
Replacing dysfunctional endocrine tissues (eg, islets) with healthy, nonautologous material protected against the immune defense of the patient could soon become a reality. Recent advances have resulted in the development of alginate-based microcapsules that meet the demands of biocompatibility, long-term integrity, and function. Focus on the development of good manufacturing practice-conforming microfluidic chip technology for generation of immunoisolated transplants and on cryopreservation technology will bring the cell-based therapy to the market and clinics.
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Affiliation(s)
- Heiko Zimmermann
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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37
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Zimmermann D, Terpitz U, Zhou A, Reuss R, Müller K, Sukhorukov VL, Gessner P, Nagel G, Zimmermann U, Bamberg E. Biophysical characterisation of electrofused giant HEK293-cells as a novel electrophysiological expression system. Biochem Biophys Res Commun 2006; 348:673-81. [PMID: 16890205 DOI: 10.1016/j.bbrc.2006.07.112] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Accepted: 07/20/2006] [Indexed: 11/25/2022]
Abstract
Giant HEK293 cells of 30-65 microm in diameter were produced by three-dimensional multi-cell electrofusion in 75 mOsm sorbitol media. These strong hypotonic conditions facilitated fusion because of the spherical shape and smooth membrane surface of the swollen cells. A regulatory volume decrease (RVD), as observed at higher osmolalities, did not occur at 75 mOsm. In contrast to field-treated, but unfused cells, the increase in volume induced by hypotonic shock was only partly reversible in the case of fused giant cells after their transfer into isotonic medium. The large size of the electrofused cells allowed the study of their electrophysiological properties by application of both whole-cell and giant excised patch-clamp techniques. Recordings on giant cells yielded a value of 1.1+/-0.1 microF/cm2 for the area-specific membrane capacitance. This value was consistent with that of the parental cells. The area-specific conductivity of giant cells (diameter > 50 microm) was found to be between 12.8 and 16.1 microS/cm2, which is in the range of that of the parental cells. Measurements with patch-pipettes containing fluorescein showed uniform dye uptake in the whole-cell configuration, but not in the cell-attached configuration. The diffusion-controlled uniform uptake of the dye into the cell interior excludes internal compartmentalisation. The finding of a homogeneous fusion was also supported by expression of the yellow fluorescent protein YFP (as part of the fusion-protein ChR2-YFP) in giant cells since no plasma-membrane bound YFP-mediated fluorescence was detected in the interior of the electrofused cells. Functional expression and the electrophysiological characterisation of the light-activated cation channel Channelrhodopsin 2 (ChR2) yielded similar results as for parental cells. Most importantly, the giant cells exhibited a comparable expression density of the channel protein in the plasma membrane as observed in parental cells. This demonstrates that electrofused cells can be used as a heterologous expression system.
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Affiliation(s)
- D Zimmermann
- Department of Biophysical Chemistry, Max-Planck-Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt am Main, Germany
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38
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Sukhorukov VL, Reuss R, Endter JM, Fehrmann S, Katsen-Globa A, Gessner P, Steinbach A, Müller KJ, Karpas A, Zimmermann U, Zimmermann H. A biophysical approach to the optimisation of dendritic-tumour cell electrofusion. Biochem Biophys Res Commun 2006; 346:829-39. [PMID: 16780801 DOI: 10.1016/j.bbrc.2006.05.193] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Accepted: 05/29/2006] [Indexed: 11/25/2022]
Abstract
Electrofusion of tumour and dendritic cells (DCs) is a promising approach for production of DC-based anti-tumour vaccines. Although human DCs are well characterised immunologically, little is known about their biophysical properties, including dielectric and osmotic parameters, both of which are essential for the development of efficient electrofusion protocols. In the present study, human DCs from the peripheral blood along with a tumour cell line used as a model fusion partner were examined by means of time-resolved cell volumetry and electrorotation. Based on the biophysical cell data, the electrofusion protocol could be rapidly optimised with respect to the sugar composition of the fusion medium, duration of hypotonic treatment, frequency range for stable cell alignment, and field strengths of breakdown pulses triggering membrane fusion. The hypotonic electrofusion consistently gave a tumour-DC hybrid rate of up to 19%, as determined by counting dually labelled fluorescent hybrids in a microscope. This fusion rate is nearly twice as high as that usually reported in the literature for isotonic media. The experimental findings and biophysical approach presented here are generally useful for the development of efficient electrofusion protocols, especially for rare and valuable human cells.
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Affiliation(s)
- Vladimir L Sukhorukov
- Lehrstuhl für Biotechnologie, Biozentrum, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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