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Silkunas M, Silkuniene G, Pakhomov AG. Real-time imaging of individual electropores proves their longevity in cells. Biochem Biophys Res Commun 2024; 695:149408. [PMID: 38157631 PMCID: PMC10842338 DOI: 10.1016/j.bbrc.2023.149408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024]
Abstract
With over 50 years of electroporation research, the nature of cell membrane permeabilization remains elusive. The lifetime of electropores in molecular models is limited to nano- or microseconds, whereas the permeabilization of electroporated cells can last minutes. This study aimed at resolving a longstanding debate on whether the prolonged permeabilization is due to the formation of long-lived pores in cells. We developed a method for dynamic monitoring and conductance measurements of individual electropores. This was accomplished by time-lapse total internal reflection fluorescence (TIRF) imaging in HEK cells loaded with CAL-520 dye and placed on an indium tin oxide (ITO) surface. Applying a 1-ms, 0 to -400 mV pulse between the patch pipette and ITO evoked focal Ca2+ transients that identified individual electropores. Some transients disappeared in milliseconds but others persisted for over a minute. Persistent transients ("Ca2+ plumes") faded over time to a stable or a randomly fluctuating level that could include periods of full quiescence. Single pore conductance, measured by 0 to -50 mV, 50 ms steps at 30 and 60 s after the electroporation, ranged from 80 to 200 pS. These experiments proved electropore longevity in cells, in stark contrast to molecular simulations and many findings in lipid bilayers.
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Affiliation(s)
- Mantas Silkunas
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA; Institute for Digestive System Research, Lithuanian University of Health Sciences, 44307, Kaunas, Lithuania
| | - Giedre Silkuniene
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA; Institute for Digestive System Research, Lithuanian University of Health Sciences, 44307, Kaunas, Lithuania
| | - Andrei G Pakhomov
- Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.
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2
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Lee D, Chan SSY, Aksic N, Bajalovic N, Loke DK. Ultralong-Time Recovery and Low-Voltage Electroporation for Biological Cell Monitoring Enabled by a Microsized Multipulse Framework. ACS OMEGA 2021; 6:35325-35333. [PMID: 34984264 PMCID: PMC8717367 DOI: 10.1021/acsomega.1c04257] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/20/2021] [Indexed: 05/05/2023]
Abstract
Long-term nondestructive monitoring of cells is of significant importance for understanding cell proliferation, cell signaling, cell death, and other processes. However, traditional monitoring methods are limited to a certain range of testing conditions and may reduce cell viability. Here, we present a microgap, multishot electroporation (M2E) system for monitoring cell recovery for up to ∼2 h using ∼5 V pulses and with excellent cell viability using a medium cell population. Electric field simulations reveal the bias-voltage- and gap-size-dependent electric field intensities in the M2E system. In addition to excellent transparency with low cell toxicity, the M2E system does not require specialized components, expensive materials, complicated fabrication processes, or cell manipulations; it just consists of a micrometer-sized pattern and a low-voltage square-wave generator. Ultimately, the M2E system can offer a long-term and nontoxic method of cell monitoring.
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Affiliation(s)
- Denise Lee
- Department
of Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Sophia S. Y. Chan
- Department
of Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Nemanja Aksic
- Department
of Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Natasa Bajalovic
- Department
of Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
| | - Desmond K. Loke
- Department
of Science, Mathematics and Technology, Singapore University of Technology and Design, Singapore 487372, Singapore
- Office
of Innovation, Changi General Hospital, Singapore 529889, Singapore
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3
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Pulse Duration Dependent Asymmetry in Molecular Transmembrane Transport Due to Electroporation in H9c2 Rat Cardiac Myoblast Cells In Vitro. Molecules 2021; 26:molecules26216571. [PMID: 34770979 PMCID: PMC8588460 DOI: 10.3390/molecules26216571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Revised: 10/09/2021] [Accepted: 10/22/2021] [Indexed: 11/17/2022] Open
Abstract
Electroporation (EP) is one of the successful physical methods for intracellular drug delivery, which temporarily permeabilizes plasma membrane by exposing cells to electric pulses. Orientation of cells in electric field is important for electroporation and, consequently, for transport of molecules through permeabilized plasma membrane. Uptake of molecules after electroporation are the greatest at poles of cells facing electrodes and is often asymmetrical. However, asymmetry reported was inconsistent and inconclusive-in different reports it was either preferentially anodal or cathodal. We investigated the asymmetry of polar uptake of calcium ions after electroporation with electric pulses of different durations, as the orientation of elongated cells affects electroporation to a different extent when using electric pulses of different durations in the range of 100 ns to 100 µs. The results show that with 1, 10, and 100 µs pulses, the uptake of calcium ions is greater at the pole closer to the cathode than at the pole closer to the anode. With shorter 100 ns pulses, the asymmetry is not observed. A different extent of electroporation at different parts of elongated cells, such as muscle or cardiac cells, may have an impact on electroporation-based treatments such as drug delivery, pulse-field ablation, and gene electrotransfection.
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Jindal S, Chockalingam S, Ghosh SS, Packirisamy G. Connexin and gap junctions: perspectives from biology to nanotechnology based therapeutics. Transl Res 2021; 235:144-167. [PMID: 33582245 DOI: 10.1016/j.trsl.2021.02.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/10/2021] [Accepted: 02/09/2021] [Indexed: 12/11/2022]
Abstract
The concept of gap junctions and their role in intercellular communication has been known for around 50 years. Considerable progress has been made in understanding the fundamental biology of connexins in mediating gap junction intercellular communication (GJIC) and their role in various cellular processes including pathological conditions. However, this understanding has not led to development of advanced therapeutics utilizing GJIC. Inadequacies in strategies that target specific connexin protein in the affected tissue, with minimal or no collateral damage, are the primary reason for the lack of development of efficient therapeutic models. Herein, nanotechnology has a role to play, giving plenty of scope to circumvent these problems and develop more efficient connexin based therapeutics. AsODN, antisense oligodeoxynucleotides; BMPs, bone morphogenetic proteins; BMSCs, bone marrow stem cells; BG, bioglass; Cx, Connexin; CxRE, connexin-responsive elements; CoCr NPs, cobalt-chromium nanoparticles; cGAMP, cyclic guanosine monophosphate-adenosine monophosphate; cAMP, cyclic adenosine monophosphate; ERK1/2, extracellular signal-regulated kinase 1/2; EMT, epithelial-mesenchymal transition; EPA, eicosapentaenoic acids; FGFR1, fibroblast growth factor receptor 1; FRAP, fluorescence recovery after photobleaching; 5-FU, 5-fluorouracil; GJ, gap junction; GJIC, gap junctional intercellular communication; HGPRTase, hypoxanthine phosphoribosyltransferase; HSV-TK, herpes virus thymidine kinase; HSA, human serum albumin; HA, hyaluronic acid; HDAC, histone deacetylase; IRI, ischemia reperfusion injury; IL-6, interleukin-6; IL-8, interleukin-8; IONPs, iron-oxide nanoparticles; JNK, c-Jun N-terminal kinase; LAMP, local activation of molecular fluorescent probe; MSCs, mesenchymal stem cells; MMP, matrix metalloproteinase; MI, myocardial infarction; MAPK, mitogen-activated protein kinase; NF-κB, nuclear factor kappa B; NO, nitric oxide; PKC, protein kinase C; QDs, quantum dots; ROI, region of interest; RGO, reduced graphene oxide; siRNA, small interfering RNA; TGF-β1, transforming growth factor-β1; TNF-α, tumor necrosis factor-α; UCN, upconversion nanoparticles; VEGF, vascular endothelial growth factor. In this review, we discuss briefly the role of connexins and gap junctions in various physiological and pathological processes, with special emphasis on cancer. We further discuss the application of nanotechnology and tissue engineering in developing treatments for various connexin based disorders.
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Affiliation(s)
- Shlok Jindal
- Nanobiotechnology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India
| | - S Chockalingam
- Department of Biotechnology, National Institute of Technology Warangal, Warangal, Telangana, India
| | - Siddhartha Sankar Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Gopinath Packirisamy
- Nanobiotechnology Laboratory, Department of Biotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India; Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, Uttarakhand, India.
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Zhou Y, Lu Y, Cheng J, Xu Y. Highly uniform in-situ cell electrotransfection of adherent cultures using grouped interdigitated electrodes. Bioelectrochemistry 2019; 132:107435. [PMID: 31855831 DOI: 10.1016/j.bioelechem.2019.107435] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 11/23/2019] [Accepted: 11/24/2019] [Indexed: 02/05/2023]
Abstract
Cell electrotransfection is an effective approach for transferring exogenous molecules into living cells by electric stimulation. The existing in-situ electrotransfection micro-devices for adherent cells exhibit the drawbacks of low transfection efficiency and low cell viability. An important reason for these drawbacks is the unequal exposure of cells to the electric field. It was found that cells growing directly below the energized electrodes experience a much lower electric field intensity when compared to the cells growing below the spacing area of the electrodes, resulting in low transfection with a strip-like pattern. Therefore, a new strategy for the in-situ electrotransfection of adherent cells growing in a standard 12-well plate is proposed in this study. By sequentially energizing electrodes arranged in a nested and non-contact manner, the cells were exposed to an overall equal intensity of the electric field, and thus a higher efficiency of transfection was achieved. The seven cell lines transfected using this method exhibited high transfection efficiency and high cell viability, demonstrating the potential for studying gene function.
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Affiliation(s)
- Yicen Zhou
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Ying Lu
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jing Cheng
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, Beijing 100084, China; Center for Precision Medicine, West China Hospital, Sichuan University, Chengdu 610041, China; National Engineering Research Center for Beijing Biochip Technology, Beijing 102206, China.
| | - Youchun Xu
- State Key Laboratory of Membrane Biology, School of Medicine, Tsinghua University, Beijing 100084, China; National Engineering Research Center for Beijing Biochip Technology, Beijing 102206, China.
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6
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Kim HB, Lee S, Shen Y, Ryu PD, Lee Y, Chung JH, Sung CK, Baik KY. Physicochemical factors that affect electroporation of lung cancer and normal cell lines. Biochem Biophys Res Commun 2019; 517:703-708. [PMID: 31387747 DOI: 10.1016/j.bbrc.2019.07.119] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 07/30/2019] [Indexed: 01/04/2023]
Abstract
Electroporation is used for cancer therapy to efficiently destroy cancer tissues by transferring anticancer drugs into cancer cells or by irreversible tumor ablation without resealing pores. There is growing interest in the electroporation method for the treatment of lung cancer, which has the highest mortality rate among cancers. Improving the cancer cell selectivity has the potential to expand its use. However, the factors that influence the cell selectivity of electroporation are debatable. We aimed to identify the important factors that influence the efficiency of electroporation in lung cells. The electropermeabilization of lung cancer cells (H460, A549, and HCC1588) and normal lung cells (MRC5, WI26 and L132) was evaluated by the transfer of fluorescence dyes. We found that membrane permeabilization increased as cell size, membrane stiffness, resting transmembrane potential, and lipid cholesterol ratio increased. Among them, lipid composition was found to be the most relevant factor in the electroporation of lung cells. Our results provide insight into the differences between lung cancer cells and normal lung cells and provide a basis for enhancing the sensitivity of lung cancers cells to electroporation.
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Affiliation(s)
- Hong Bae Kim
- Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul, 08826, South Korea
| | - Seho Lee
- Department of Brain and Cognitive Engineering, Korea University, Seoul, 02841, South Korea
| | - Yiming Shen
- Department of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, South Korea
| | - Pan-Dong Ryu
- Department of Veterinary Pharmacology, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, 08826, South Korea
| | - Yunmi Lee
- Department of Chemistry, Kwangwoon University, Seoul, 01897, South Korea
| | - Jong Hoon Chung
- Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul, 08826, South Korea
| | - Chang Kyu Sung
- Department of Radiology, Seoul National University College of Medicine, Seoul, 07061, South Korea.
| | - Ku Youn Baik
- Department of Electrical and Biological Physics, Kwangwoon University, Seoul, 01897, South Korea.
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7
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Ye H, Ng J. Shielding effects of myelin sheath on axolemma depolarization under transverse electric field stimulation. PeerJ 2018; 6:e6020. [PMID: 30533309 PMCID: PMC6282940 DOI: 10.7717/peerj.6020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 10/29/2018] [Indexed: 01/14/2023] Open
Abstract
Axonal stimulation with electric currents is an effective method for controlling neural activity. An electric field parallel to the axon is widely accepted as the predominant component in the activation of an axon. However, recent studies indicate that the transverse component to the axolemma is also effective in depolarizing the axon. To quantitatively investigate the amount of axolemma polarization induced by a transverse electric field, we computed the transmembrane potential (Vm) for a conductive body that represents an unmyelinated axon (or the bare axon between the myelin sheath in a myelinated axon). We also computed the transmembrane potential of the sheath-covered axonal segment in a myelinated axon. We then systematically analyzed the biophysical factors that affect axonal polarization under transverse electric stimulation for both the bare and sheath-covered axons. Geometrical patterns of polarization of both axon types were dependent on field properties (magnitude and field orientation to the axon). Polarization of both axons was also dependent on their axolemma radii and electrical conductivities. The myelin provided a significant “shielding effect” against the transverse electric fields, preventing excessive axolemma depolarization. Demyelination could allow for prominent axolemma depolarization in the transverse electric field, via a significant increase in myelin conductivity. This shifts the voltage drop of the myelin sheath to the axolemma. Pathological changes at a cellular level should be considered when electric fields are used for the treatment of demyelination diseases. The calculated term for membrane polarization (Vm) could be used to modify the current cable equation that describes axon excitation by an external electric field to account for the activating effects of both parallel and transverse fields surrounding the target axon.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University of Chicago, Chicago, IL, USA
| | - Jeffrey Ng
- Department of Biology, Loyola University of Chicago, Chicago, IL, USA
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8
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Batista Napotnik T, Miklavčič D. In vitro electroporation detection methods – An overview. Bioelectrochemistry 2018; 120:166-182. [DOI: 10.1016/j.bioelechem.2017.12.005] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/11/2017] [Accepted: 12/11/2017] [Indexed: 12/22/2022]
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9
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Suarez Castellanos IM, Balteanu B, Singh T, Zderic V. Therapeutic Modulation of Calcium Dynamics Using Ultrasound and Other Energy-Based Techniques. IEEE Rev Biomed Eng 2016; 9:177-191. [DOI: 10.1109/rbme.2016.2555760] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Electroporation Loading and Dye Transfer: A Safe and Robust Method to Probe Gap Junctional Coupling. Methods Mol Biol 2016; 1437:155-69. [PMID: 27207293 DOI: 10.1007/978-1-4939-3664-9_11] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intercellular communication occurring via gap junction channels is considered a key mechanism for synchronizing physiological functions of cells and for the maintenance of tissue homeostasis. Gap junction channels are protein channels that are situated between neighboring cells and that provide a direct, yet selective route for the passage of small hydrophilic biomolecules and ions. Here, an electroporation method is described to load a localized area within an adherent cell monolayer with a gap junction-permeable fluorescent reporter dye. The technique results in a rapid and efficient labeling of a small patch of cells within the cell culture, without affecting cellular viability. Dynamic and quantitative information on gap junctional communication can subsequently be extracted by tracing the intercellular movement of the dye via time-lapse microscopy.
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11
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A novel perspective on neuron study: damaging and promoting effects in different neurons induced by mechanical stress. Biomech Model Mechanobiol 2015; 15:1019-27. [DOI: 10.1007/s10237-015-0743-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 10/29/2015] [Indexed: 12/11/2022]
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12
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Ye H, Steiger A. Neuron matters: electric activation of neuronal tissue is dependent on the interaction between the neuron and the electric field. J Neuroeng Rehabil 2015; 12:65. [PMID: 26265444 PMCID: PMC4534030 DOI: 10.1186/s12984-015-0061-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Accepted: 08/07/2015] [Indexed: 01/09/2023] Open
Abstract
In laboratory research and clinical practice, externally-applied electric fields have been widely used to control neuronal activity. It is generally accepted that neuronal excitability is controlled by electric current that depolarizes or hyperpolarizes the excitable cell membrane. What determines the amount of polarization? Research on the mechanisms of electric stimulation focus on the optimal control of the field properties (frequency, amplitude, and direction of the electric currents) to improve stimulation outcomes. Emerging evidence from modeling and experimental studies support the existence of interactions between the targeted neurons and the externally-applied electric fields. With cell-field interaction, we suggest a two-way process. When a neuron is positioned inside an electric field, the electric field will induce a change in the resting membrane potential by superimposing an electrically-induced transmembrane potential (ITP). At the same time, the electric field can be perturbed and re-distributed by the cell. This cell-field interaction may play a significant role in the overall effects of stimulation. The redistributed field can cause secondary effects to neighboring cells by altering their geometrical pattern and amount of membrane polarization. Neurons excited by the externally-applied electric field can also affect neighboring cells by ephaptic interaction. Both aspects of the cell-field interaction depend on the biophysical properties of the neuronal tissue, including geometric (i.e., size, shape, orientation to the field) and electric (i.e., conductivity and dielectricity) attributes of the cells. The biophysical basis of the cell-field interaction can be explained by the electromagnetism theory. Further experimental and simulation studies on electric stimulation of neuronal tissue should consider the prospect of a cell-field interaction, and a better understanding of tissue inhomogeneity and anisotropy is needed to fully appreciate the neural basis of cell-field interaction as well as the biological effects of electric stimulation.
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Affiliation(s)
- Hui Ye
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Rd, Chicago, IL, 60660, USA.
| | - Amanda Steiger
- Department of Biology, Loyola University Chicago, 1032 W. Sheridan Rd, Chicago, IL, 60660, USA.
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Trainito CI, Français O, Le Pioufle B. Monitoring the permeabilization of a single cell in a microfluidic device, through the estimation of its dielectric properties based on combined dielectrophoresis and electrorotation in situ experiments. Electrophoresis 2015; 36:1115-22. [PMID: 25641658 DOI: 10.1002/elps.201400482] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 01/01/2015] [Accepted: 01/19/2015] [Indexed: 11/08/2022]
Abstract
The electric field is commonly used in microdevices to handle, treat, or monitor living cells for various biological or biomedical applications (cells electrofusion, gene electrotransfer, drugs injection, cell sorting, …). Dielectrophoresis (DEP) forces, using stationary waves (conventional DEP) or traveling waves, are widely used for the cell handling or sorting. Electrorotation, which is induced by a rotating electrical field, is used for the determination of cell dielectric parameters. The application of pulsed electric field (PEF) results in the cell membrane permeabilization that might allow the transfer of various molecules in the cytoplasm. In this paper, we propose a method to monitor in situ the level of electropermeabilization induced by PEF application on a single cell, by combining the dielectrophoresis force and the electrorotation torque within a microfluidic device. The method was experimented on two different cell lines (human leukemic T-cell lymphoblast and murine melanoma cell): a single cell is captured by dielectrophoresis while its dielectric properties (both permittivity and conductivity of cytoplasm and membrane) are estimated thanks to a rotating electric field, which is applied simultaneously. The permeabilization effect of PEF, applied to the single cell trapped in such conditions in the biodevice, could be monitored by the estimation of its dielectric properties before and after pulse application.
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14
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Venslauskas MS, Šatkauskas S. Mechanisms of transfer of bioactive molecules through the cell membrane by electroporation. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:277-89. [PMID: 25939984 DOI: 10.1007/s00249-015-1025-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 03/26/2015] [Accepted: 04/07/2015] [Indexed: 01/19/2023]
Abstract
A short review of biophysical mechanisms for electrotransfer of bioactive molecules through the cell membrane by using electroporation is presented. The concept of transient hydrophilic aqueous pores and membrane electroporation mechanisms of single cells and cells in suspension models are analyzed. Alongside the theoretical approach, some peculiarities of drug and gene electrotransfer into cells and applications in clinical trials are discussed.
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Affiliation(s)
- Mindaugas S Venslauskas
- Biophysical Research Group, Department of Biology, Faculty of Natural Sciences, Vytautas Magnus University, Vileikos 8, 44404, Kaunas, Lithuania,
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15
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Decrock E, De Bock M, Wang N, Bol M, Gadicherla AK, Leybaert L. Electroporation loading and flash photolysis to investigate intra- and intercellular Ca2+ signaling. Cold Spring Harb Protoc 2015; 2015:239-49. [PMID: 25734071 DOI: 10.1101/pdb.top066068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Many cellular functions are driven by variations in the intracellular Ca(2+) concentration ([Ca(2+)]i), which may appear as a single-event transient [Ca(2+)]i elevation, repetitive [Ca(2+)]i increases known as Ca(2+) oscillations, or [Ca(2+)]i increases propagating in the cytoplasm as Ca(2+) waves. Additionally, [Ca(2+)]i changes can be communicated between cells as intercellular Ca(2+) waves (ICWs). ICWs are mediated by two possible mechanisms acting in parallel: one involving gap junctions that form channels directly linking the cytoplasm of adjacent cells and one involving a paracrine messenger, in most cases ATP, that is released into the extracellular space, leading to [Ca(2+)]i changes in neighboring cells. The intracellular messenger inositol 1,4,5-trisphosphate (IP3) that triggers Ca(2+) release from Ca(2+) stores is crucial in these two ICW propagation scenarios, and is also a potent trigger to initiate ICWs. Loading inactive, "caged" IP3 into cells followed by photolytic "uncaging" with UV light, thereby liberating IP3, is a well-established method to trigger [Ca(2+)]i changes in single cells that is also effective in initiating ICWs. We here describe a method to load cells with caged IP3 by local electroporation of monolayer cell cultures and to apply flash photolysis to increase intracellular IP3 and induce [Ca(2+)]i changes, or initiate ICWs. Moreover, the electroporation method allows loading of membrane-impermeable agents that interfere with IP3 and Ca(2+) signaling.
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Affiliation(s)
- Elke Decrock
- Department of Basic Medical Sciences, Physiology Group, Ghent University, 9000 Ghent, Belgium
| | - Marijke De Bock
- Department of Basic Medical Sciences, Physiology Group, Ghent University, 9000 Ghent, Belgium
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology Group, Ghent University, 9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology Group, Ghent University, 9000 Ghent, Belgium
| | - Ashish K Gadicherla
- Department of Basic Medical Sciences, Physiology Group, Ghent University, 9000 Ghent, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology Group, Ghent University, 9000 Ghent, Belgium
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16
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Newbold C, Farrington A, Peters L, Cowan R, Needham K. Electropermeabilization of Adherent Cells with Cochlear Implant Electrical Stimulation in vitro. Audiol Neurootol 2014; 19:283-92. [DOI: 10.1159/000362588] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 03/31/2014] [Indexed: 11/19/2022] Open
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17
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Escoffre JM, Bellard E, Faurie C, Sébaï SC, Golzio M, Teissié J, Rols MP. Membrane disorder and phospholipid scrambling in electropermeabilized and viable cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:1701-9. [PMID: 24583083 DOI: 10.1016/j.bbamem.2014.02.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 02/11/2014] [Accepted: 02/19/2014] [Indexed: 11/25/2022]
Abstract
Membrane electropermeabilization relies on the transient permeabilization of the plasma membrane of cells submitted to electric pulses. This method is widely used in cell biology and medicine due to its efficiency to transfer molecules while limiting loss of cell viability. However, very little is known about the consequences of membrane electropermeabilization at the molecular and cellular levels. Progress in the knowledge of the involved mechanisms is a biophysical challenge. As a transient loss of membrane cohesion is associated with membrane permeabilization, our main objective was to detect and visualize at the single-cell level the incidence of phospholipid scrambling and changes in membrane order. We performed studies using fluorescence microscopy with C6-NBD-PC and FM1-43 to monitor phospholipid scrambling and membrane order of mammalian cells. Millisecond permeabilizing pulses induced membrane disorganization by increasing the translocation of phosphatidylcholines according to an ATP-independent process. The pulses induced the formation of long-lived permeant structures that were present during membrane resealing, but were not associated with phosphatidylcholine internalization. These pulses resulted in a rapid phospholipid flip/flop within less than 1s and were exclusively restricted to the regions of the permeabilized membrane. Under such electrical conditions, phosphatidylserine externalization was not detected. Moreover, this electrically-mediated membrane disorganization was not correlated with loss of cell viability. Our results could support the existence of direct interactions between the movement of membrane zwitterionic phospholipids and the electric field.
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Affiliation(s)
- Jean-Michel Escoffre
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077, Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077, Toulouse, France
| | - Elisabeth Bellard
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077, Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077, Toulouse, France
| | - Cécile Faurie
- Matwin-Institut Bergonié, 229 cours de l'Argonne, 33076 Bordeaux cedex, France
| | - Sarra C Sébaï
- Eviagenics, Immeuble Villejuif Biopark, 1 Mail du Professeur Georges Mathé, 94800 Villejuif, France
| | - Muriel Golzio
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077, Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077, Toulouse, France
| | - Justin Teissié
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077, Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077, Toulouse, France.
| | - Marie-Pierre Rols
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), 205 route de Narbonne, F-31077, Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077, Toulouse, France.
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18
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Xu Y, Lu Y, Xing W. An individually addressable suspended-drop electroporation system for high-throughput cell transfection. LAB ON A CHIP 2014; 14:686-690. [PMID: 24336759 DOI: 10.1039/c3lc50907a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
High-efficiency transfection of genes, proteins, or drug compounds into cells without causing permanent damage is a prerequisite for many cell biology experiments. Here, we report a printed circuit board (PCB)-based electroporation device for high-throughput delivery of exogenous molecules into cells in an individually addressable manner. This device incorporates an array of 96 through-holes on the PCB with a pair of gold coated symmetric electrodes plated on the wall of each through-hole. A mixture of cell suspension and exogenous molecules is top-loaded, electroporated, and bottom-ejected with cell culture medium into the corresponding well of a 96-well plate placed under the PCB. One group of electrodes on the same side of the 96 through-holes were connected to eight top pads via connecting row wires plated on the top surface of the PCB and the other group of electrodes were connected in a column format to twelve bottom pads. Therefore, each pair of electrodes can be selectively energized, guaranteeing that appropriate electroporation parameters can be applied to different holes. We demonstrate the use of the present device to effectively introduce plasmid DNA and synthetic interfering RNA into cultured and primary cells with high cell viability and transfection efficiency. The high performance and low cost features make our device an ideal platform for cellular and molecular research and high-throughput screening.
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Affiliation(s)
- Youchun Xu
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China.
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19
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Tsugiyama H, Okimura C, Mizuno T, Iwadate Y. Electroporation of adherent cells with low sample volumes on a microscope stage. ACTA ACUST UNITED AC 2013; 216:3591-8. [PMID: 23788710 DOI: 10.1242/jeb.089870] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The labeling of specific molecules and their artificial control in living cells are powerful techniques for investigating intracellular molecular dynamics. To use these techniques, molecular compounds (hereinafter described simply as 'samples') need to be loaded into cells. Electroporation techniques are exploited to load membrane-impermeant samples into cells. Here, we developed a new electroporator with four special characteristics. (1) Electric pulses are applied to the adherent cells directly, without removing them from the substratum. (2) Samples can be loaded into the adherent cells while observing them on the stage of an inverted microscope. (3) Only 2 μl of sample solution is sufficient. (4) The device is very easy to use, as the cuvette, which is connected to the tip of a commercially available auto-pipette, is manipulated by hand. Using our device, we loaded a fluorescent probe of actin filaments, Alexa Fluor 546 phalloidin, into migrating keratocytes. The level of this probe in the cells could be easily adjusted by changing its concentration in the electroporation medium. Samples could be loaded into keratocytes, neutrophil-like HL-60 cells and Dictyostelium cells on a coverslip, and keratocytes on an elastic silicone substratum. The new device should be useful for a wide range of adherent cells and allow electroporation for cells on various types of the substrata.
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Affiliation(s)
- Harunobu Tsugiyama
- Department of Functional Molecular Biology, Graduate School of Medicine, Yamaguchi University, Yamaguchi 753-8512, Japan
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20
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Hai A, Spira ME. On-chip electroporation, membrane repair dynamics and transient in-cell recordings by arrays of gold mushroom-shaped microelectrodes. LAB ON A CHIP 2012; 12:2865-73. [PMID: 22678065 DOI: 10.1039/c2lc40091j] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
This study demonstrates the use of on-chip gold mushroom-shaped microelectrodes (gMμEs) to generate localized electropores in the plasma membrane of adhering cultured neurons and to electrophysiologically monitor the ensuing membrane repair dynamics. Delivery of an alternating voltage pulse (0.5-1 V, 100 Hz, 300 ms) through an extracellularly positioned micrometer-sized gMμE electroporates the patch of plasma membrane facing the microelectrode. The repair dynamics of the electropores were analyzed by continuous monitoring of the neuron transmembrane potential, input resistance (R(in)) and action potential (AP) amplitude with an intracellular microelectrode and a number of neighbouring extracellular gMμEs. Electroporation by a gMμE is associated with local elevation of the free intracellular calcium concentration ([Ca(2+)](i)) around the gMμE. The membrane repair kinetics proceeds as an exponential process interrupted by abrupt recovery steps. These abrupt events are consistent with the "membrane patch model" of membrane repair in which patches of intracellular membrane fuse with the plasma membrane at the site of injury. Membrane electroporation by a single gMμE generates a neuron-gMμE configuration that permits recordings of attenuated intracellular action potentials. We conclude that the use of on-chip cultured neurons via a gMμE configuration provides a unique neuroelectronic interface that enables the selection of individual cells for electroporation, generates a confined electroporated membrane patch, monitors membrane repair dynamics and records attenuated intracellular action potentials.
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Affiliation(s)
- Aviad Hai
- Department of Neurobiology the Life Sciences Institute, and the Harvey M. Kruger Family center for Nanoscience and Nanotechnology. The Hebrew University of Jerusalem, Jerusalem, Israel
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21
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Ye H, Cotic M, Fehlings MG, Carlen PL. INFLUENCE OF CELLULAR PROPERTIES ON THE ELECTRIC FIELD DISTRIBUTION AROUND A SINGLE CELL. ACTA ACUST UNITED AC 2012. [DOI: 10.2528/pierb11122705] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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22
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Osmotic stress alters chromatin condensation and nucleocytoplasmic transport. Biochem Biophys Res Commun 2011; 408:230-5. [PMID: 21463604 DOI: 10.1016/j.bbrc.2011.03.131] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 03/30/2011] [Indexed: 11/22/2022]
Abstract
Osmotic stress is a potent regulator of biological function in many cell types, but its mechanism of action is only partially understood. In this study, we examined whether changes in extracellular osmolality can alter chromatin condensation and the rate of nucleocytoplasmic transport, as potential mechanisms by which osmotic stress can act. Transport of 10 kDa dextran was measured both within and between the nucleus and the cytoplasm using two different photobleaching methods. A mathematical model was developed to describe fluorescence recovery via nucleocytoplasmic transport. As osmolality increased, the diffusion coefficient of dextran decreased in the cytoplasm, but not the nucleus. Hyper-osmotic stress decreased nuclear size and increased nuclear lacunarity, indicating that while the nucleus was getting smaller, the pores and channels interdigitating the chromatin had expanded. The rate of nucleocytoplasmic transport was increased under hyper-osmotic stress but was insensitive to hypo-osmotic stress, consistent with the nonlinear osmotic properties of the nucleus. The mechanism of this osmotic sensitivity appears to be a change in the size and geometry of the nucleus, resulting in a shorter effective diffusion distance for the nucleus. These results may explain physical mechanisms by which osmotic stress can influence intracellular signaling pathways that rely on nucleocytoplasmic transport.
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23
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Giacomello M, Girardi S, Scorzeto M, Peruffo A, Maschietto M, Cozzi B, Vassanelli S. Stimulation of Ca²+ signals in neurons by electrically coupled electrolyte-oxide-semiconductor capacitors. J Neurosci Methods 2011; 198:1-7. [PMID: 21345350 DOI: 10.1016/j.jneumeth.2011.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 02/10/2011] [Accepted: 02/11/2011] [Indexed: 01/12/2023]
Abstract
Electrolyte-oxide-semiconductor capacitors (EOSCs) are a class of microtransducers for extracellular electrical stimulation that have been successfully employed to activate voltage-dependent sodium channels at the neuronal soma to generate action potentials in vitro. In the present work, we report on their use to control Ca²+ signalling in cultured mammalian cells, including neurons. Evidence is provided that EOSC stimulation with voltage waveforms in the microsecond or nanosecond range activates two distinct Ca²+ pathways, either by triggering Ca²+ entry through the plasma membrane or its release from intracellular stores. Ca²+ signals were activated in non-neuronal and neuronal cell lines, CHO-K1 and SH-SY5Y. On this basis, stimulation was tailored to rat and bovine neurons to mimic physiological somatic Ca²+ transients evoked by glutamate. Being minimally invasive and easy to use, the new method represents a versatile complement to standard electrophysiology and imaging techniques for the investigation of Ca²+ signalling in dissociated primary neurons and cell lines.
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Affiliation(s)
- M Giacomello
- Department of Experimental Veterinary Science, University of Padova, viale dell'Università 16, 35020 Legnaro-Agripolis (PD), Italy
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24
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Ye H, Cotic M, Fehlings MG, Carlen PL. Transmembrane potential generated by a magnetically induced transverse electric field in a cylindrical axonal model. Med Biol Eng Comput 2010; 49:107-19. [PMID: 21063912 DOI: 10.1007/s11517-010-0704-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 10/21/2010] [Indexed: 11/26/2022]
Abstract
During the electrical stimulation of a uniform, long, and straight nerve axon, the electric field oriented parallel to the axon has been widely accepted as the major field component that activates the axon. Recent experimental evidence has shown that the electric field oriented transverse to the axon is also sufficient to activate the axon, by inducing a transmembrane potential within the axon. The transverse field can be generated by a time-varying magnetic field via electromagnetic induction. The aim of this study was to investigate the factors that influence the transmembrane potential induced by a transverse field during magnetic stimulation. Using an unmyelinated axon model, we have provided an analytic expression for the transmembrane potential under spatially uniform, time-varying magnetic stimulation. Polarization of the axon was dependent on the properties of the magnetic field (i.e., orientation to the axon, magnitude, and frequency). Polarization of the axon was also dependent on its own geometrical (i.e., radius of the axon and thickness of the membrane) and electrical properties (i.e., conductivities and dielectric permittivities). Therefore, this article provides evidence that aside from optimal coil design, tissue properties may also play an important role in determining the efficacy of axonal activation under magnetic stimulation. The mathematical basis of this conclusion was discussed. The analytic solution can potentially be used to modify the activation function in current cable equations describing magnetic stimulation.
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Affiliation(s)
- Hui Ye
- Toronto Western Research Institute, University Health Network, Toronto, ON, Canada.
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25
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Mechanisms for the intracellular manipulation of organelles by conventional electroporation. Biophys J 2010; 98:2506-14. [PMID: 20513394 DOI: 10.1016/j.bpj.2010.02.035] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2009] [Revised: 01/22/2010] [Accepted: 02/12/2010] [Indexed: 01/04/2023] Open
Abstract
Conventional electroporation (EP) changes both the conductance and molecular permeability of the plasma membrane (PM) of cells and is a standard method for delivering both biologically active and probe molecules of a wide range of sizes into cells. However, the underlying mechanisms at the molecular and cellular levels remain controversial. Here we introduce a mathematical cell model that contains representative organelles (nucleus, endoplasmic reticulum, mitochondria) and includes a dynamic EP model, which describes formation, expansion, contraction, and destruction for the plasma and all organelle membranes. We show that conventional EP provides transient electrical pathways into the cell, sufficient to create significant intracellular fields. This emerging intracellular electrical field is a secondary effect due to EP and can cause transmembrane voltages at the organelles, which are large enough and long enough to gate organelle channels, and even sufficient, at some field strengths, for the poration of organelle membranes. This suggests an alternative to nanosecond pulsed electric fields for intracellular manipulations.
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26
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Kotnik T, Pucihar G, Miklavcic D. Induced transmembrane voltage and its correlation with electroporation-mediated molecular transport. J Membr Biol 2010; 236:3-13. [PMID: 20617432 DOI: 10.1007/s00232-010-9279-9] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2009] [Accepted: 06/11/2010] [Indexed: 01/17/2023]
Abstract
Exposure of a cell to an electric field results in inducement of a voltage across its membrane (induced transmembrane voltage, DeltaPsi (m)) and, for sufficiently strong fields, in a transient increase of membrane permeability (electroporation). We review the analytical, numerical and experimental methods for determination of DeltaPsi (m) and a method for monitoring of transmembrane transport. We then combine these methods to investigate the correlation between DeltaPsi (m) and molecular transport through an electroporated membrane for isolated cells of regular and irregular shapes, for cells in dense suspensions as well as for cells in monolayer clusters. Our experiments on isolated cells of both regular and irregular shapes confirm the theoretical prediction that the highest absolute values of DeltaPsi (m) are found in the membrane regions facing the electrodes and that electroporation-mediated transport is confined to these same regions. For cells in clusters, the location of transport regions implies that, at the field strengths sufficient for electroporation, the cells behave as electrically insulated (i.e., as individual) cells. In contrast, with substantially weaker, nonelectroporating fields, potentiometric measurements show that the cells in these same clusters behave as electrically interconnected cells (i.e., as one large cell). These results suggest that sufficiently high electric fields affect the intercellular pathways and thus alter the electric behavior of the cells with respect to their normal physiological state.
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Affiliation(s)
- Tadej Kotnik
- Department of Biomedical Engineering, Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, 1000, Ljubljana, Slovenia
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27
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Kera SA, Agerwala SM, Horne JH. The temporal resolution of in vivo electroporation in zebrafish: a method for time-resolved loss of function. Zebrafish 2010; 7:97-108. [PMID: 20192851 DOI: 10.1089/zeb.2009.0620] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
One caveat to current loss-of-function approaches in zebrafish is that they typically disrupt gene function from the beginning of development. This can be problematic when attempting to study later developmental events. In vivo electroporation is a method that has been shown to be effective at incorporating reagents into the developing nervous system at multiple later developmental stages. The temporal and spatial characteristics of in vivo electroporation that have been previously demonstrated suggest that this could be a powerful approach for time-resolved loss-of-function analysis. Here, in an attempt to demonstrate the efficacy of this approach for analysis of a specific developmental timeframe--that of initial development of the zebrafish visual system-we have done a systematic characterization of the efficiency of in vivo electroporation in zebrafish across multiple developmental stages, from 24 to 96 h postfertilization. We show that electroporation is efficient at delivering expression plasmids to large numbers of neurons at multiple developmental steps, including 24, 48, or 96 h postfertilization. Expression from electroporated plasmids is maximal within 24 h, and significant and useful expression is seen within 6 h. Electroporation can be used to deliver two separate expression plasmids (green fluorescent protein and mCherry), resulting in coexpression in 97% of cells. Most importantly, electroporation can be used to incorporate siRNA reagents, resulting in 84% knockdown of a target protein (green fluorescent protein). In conclusion, in vivo electroporation is an effective method for delivering both DNA-based expression plasmids and RNA interference-based loss-of-function reagents, and exhibits the appropriate characteristics to be useful as a time-resolved genetic approach to investigate the molecular mechanisms of visual system development.
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Affiliation(s)
- Scott A Kera
- Department of Biology and Health Sciences, Pace University, Pleasantville, New York 10570, USA
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28
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Braeken D, Huys R, Jans D, Loo J, Severi S, Vleugels F, Borghs G, Callewaert G, Bartic C. Local electrical stimulation of single adherent cells using three-dimensional electrode arrays with small interelectrode distances. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:2756-9. [PMID: 19964592 DOI: 10.1109/iembs.2009.5333871] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In this paper, we describe the localized and selective electrical stimulation of single cells using a three-dimensional electrode array. The chip consisted of 84 nail-like electrodes with a stimulation surface of 0.8 microm(2) and interelectrode distances as small as 3 microm. N2A cells were used to compare bipolar stimulation between one electrode in- and one outside the cell on the one hand, and two electrodes in the same cell on the other hand. Selective and localized stimulation of primary embryonic cardiomyocytes showed the possibility to use this chip with excitable cells. The response of the cells to applied electrical fields was monitored using calcium imaging whereas assessment of electroporation was determined following influx of propidium iodide. Arrays of these three-dimensional electrodes could eventually be used as a tool to selectively electroporate the membrane of single cells for genetic manipulation or to obtain electrical access to the inner compartment of the cell.
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Affiliation(s)
- Dries Braeken
- Interuniversity MicroElectronics Center (IMEC), Kapeldreef 75, 3001 Leuven, Belgium.
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29
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Ye H, Cotic M, Kang EE, Fehlings MG, Carlen PL. Transmembrane potential induced on the internal organelle by a time-varying magnetic field: a model study. J Neuroeng Rehabil 2010; 7:12. [PMID: 20170538 PMCID: PMC2836366 DOI: 10.1186/1743-0003-7-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Accepted: 02/20/2010] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND When a cell is exposed to a time-varying magnetic field, this leads to an induced voltage on the cytoplasmic membrane, as well as on the membranes of the internal organelles, such as mitochondria. These potential changes in the organelles could have a significant impact on their functionality. However, a quantitative analysis on the magnetically-induced membrane potential on the internal organelles has not been performed. METHODS Using a two-shell model, we provided the first analytical solution for the transmembrane potential in the organelle membrane induced by a time-varying magnetic field. We then analyzed factors that impact on the polarization of the organelle, including the frequency of the magnetic field, the presence of the outer cytoplasmic membrane, and electrical and geometrical parameters of the cytoplasmic membrane and the organelle membrane. RESULTS The amount of polarization in the organelle was less than its counterpart in the cytoplasmic membrane. This was largely due to the presence of the cell membrane, which "shielded" the internal organelle from excessive polarization by the field. Organelle polarization was largely dependent on the frequency of the magnetic field, and its polarization was not significant under the low frequency band used for transcranial magnetic stimulation (TMS). Both the properties of the cytoplasmic and the organelle membranes affect the polarization of the internal organelle in a frequency-dependent manner. CONCLUSIONS The work provided a theoretical framework and insights into factors affecting mitochondrial function under time-varying magnetic stimulation, and provided evidence that TMS does not affect normal mitochondrial functionality by altering its membrane potential.
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Affiliation(s)
- Hui Ye
- Toronto Western Research Institute, University Health Network, Ontario, Canada .
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30
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Ben-Or A, Rubinsky B. Experimental Studies on Irreversible Electroporation of Cells. IRREVERSIBLE ELECTROPORATION 2010. [DOI: 10.1007/978-3-642-05420-4_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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31
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Chang WC, Sretavan DW. Single cell and neural process experimentation using laterally applied electrical fields between pairs of closely apposed microelectrodes with vertical sidewalls. Biosens Bioelectron 2009; 24:3600-7. [PMID: 19535240 DOI: 10.1016/j.bios.2009.05.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Revised: 05/14/2009] [Accepted: 05/19/2009] [Indexed: 11/25/2022]
Abstract
As biomedical research has moved increasingly towards experimentation on single cells and subcellular structures, there has been a need for microscale devices that can perform manipulation and stimulation at a correspondingly small scale. We propose a microelectrode array (MEA) featuring thickened microelectrodes with vertical sidewalls (VSW) to focus electrical fields horizontally on targets positioned in between paired electrodes. These microelectrodes were fabricated using gold electroplating that was molded by photolithographically patterned SU-8 photoresist. Finite element modeling showed that paired VSW electrodes produce more uniform electrical fields compared to conventional planar microelectrodes. Using paired microelectrodes, 3 microm thick and spaced 10 microm apart, we were able to perform local electroporation of individual axonal processes, as demonstrated by entry of EGTA to locally chelate intra-axonal calcium, quenching the fluorescence of a pre-loaded calcium indicator dye. The same electrode configuration was used to electroporate individual cells, resulting in the targeted transfection of a transgene expressing a cytoplasmically soluble green fluorescent protein (GFP). In addition to electroporation, our electrode configuration was also capable of precisely targeted field stimulation on individual neurons, resulting in action potentials that could be tracked by optical means. With its ability to deliver well-characterized electrical fields and its versatility, our configuration of paired VSW electrodes may provide the basis for a new tool for high-throughput and high-content experimentation in broad areas of neuroscience and biomedical research.
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Affiliation(s)
- Wesley C Chang
- Department of Ophthalmology, University of California, K110, Box 0730, UC San Francisco, 10 Koret Way, K-110, San Francisco, CA 94143, USA.
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32
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Pucihar G, Miklavcic D, Kotnik T. A time-dependent numerical model of transmembrane voltage inducement and electroporation of irregularly shaped cells. IEEE Trans Biomed Eng 2009; 56:1491-501. [PMID: 19203876 DOI: 10.1109/tbme.2009.2014244] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We describe a finite-element model of a realistic irregularly shaped biological cell in an external electric field that allows the calculation of time-dependent changes of the induced transmembrane voltage (Delta Psi) and simulation of cell membrane electroporation. The model was first tested by comparing its results to the time-dependent analytical solution for Delta Psi on a nonporated spherical cell, and a good agreement was obtained. To simulate electroporation, the model was extended by introducing a variable membrane conductivity. In the regions exposed to a sufficiently high Delta Psi, the membrane conductivity rapidly increased with time, leading to a modified spatial distribution of Delta Psi. We show that steady-state models are insufficient for accurate description of Delta Psi, as well as determination of electroporated regions of the membrane, and time-dependent models should be used instead. Our modeling approach also allows direct comparison of calculations and experiments. As an example, we show that calculated regions of electroporation correspond to the regions of molecular transport observed experimentally on the same cell from which the model was constructed. Both the time-dependent model of Delta Psi and the model of electroporation can be exploited further to study the behavior of more complicated cell systems, including those with cell-to-cell interactions.
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Affiliation(s)
- Gorazd Pucihar
- Faculty of Electrical Engineering, University of Ljubljana, Ljubljana SI-1000, Slovenia.
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33
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Barker M, Billups B, Hamann M. Focal macromolecule delivery in neuronal tissue using simultaneous pressure ejection and local electroporation. J Neurosci Methods 2008; 177:273-84. [PMID: 19014970 PMCID: PMC2680959 DOI: 10.1016/j.jneumeth.2008.10.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2008] [Revised: 10/08/2008] [Accepted: 10/10/2008] [Indexed: 11/19/2022]
Abstract
Electroporation creates transient pores in the plasma membrane to introduce macromolecules within a cell or cell population. Generally, electrical pulses are delivered between two electrodes separated from each other, making electroporation less likely to be localised. We have developed a new device combining local pressure ejection with local electroporation through a double-barrelled glass micropipette to transfer impermeable macromolecules in brain slices or in cultured HEK293 cells. The design achieves better targeting of the site of pressure ejection with that of electroporation. With this technique, we have been able to limit the delivery of propidium iodide or dextran amine within areas of 100–200 μm diameter. We confirm that local electroporation is transient and show that when combined with pressure ejection, it allows local transfection of EGFP plasmids within HEK293 cells or within cerebellar and hippocampal slice cultures. We further show that local electroporation is less damaging when compared to global electroporation using two separate electrodes. Focal delivery of dextran amine dyes within trapezoid body fibres allowed tracing axonal tracts within brainstem slices, enabling the study of identified calyx of Held presynaptic terminals in living brain tissue. This labelling method can be used to target small nuclei in neuronal tissue and is generally applicable to the study of functional synaptic connectivity, or live axonal tracing in a variety of brain areas.
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Affiliation(s)
- Matthew Barker
- Department of Cell Physiology and Pharmacology, Leicester University, Medical Sciences Building, P.O. Box 138, University Road, Leicester LE1 9HN, UK
| | - Brian Billups
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1PD, UK
| | - Martine Hamann
- Department of Cell Physiology and Pharmacology, Leicester University, Medical Sciences Building, P.O. Box 138, University Road, Leicester LE1 9HN, UK
- Corresponding author. Tel.: +44 116 252 3074.
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Abstract
The transport of propidium iodide into electropermeabilized Chinese hamster ovary cells was monitored with a photomultiplier tube during and after the electric pulse. The influence of pulse amplitude and duration on the transport kinetics was investigated with time resolutions from 200 ns to 4 ms in intervals from 400 micros to 8 s. The transport became detectable as early as 60 micros after the start of the pulse, continued for tens of seconds after the pulse, and was faster and larger for higher pulse amplitudes and/or longer pulse durations. With fixed pulse parameters, transport into confluent monolayers of cells was slower than transport into suspended cells. Different time courses of fluorescence increase were observed during and at various times after the pulse, reflecting different transport mechanisms and ongoing membrane resealing. The data were compared to theoretical predictions of the Nernst-Planck equation. After a delay of 60 micros, the time course of fluorescence during the pulse was approximately linear, supporting a mainly electrophoretic solution of the Nernst-Planck equation. The time course after the pulse agreed with diffusional solution of the Nernst-Planck equation if the membrane resealing was assumed to consist of three distinct components, with time constants in the range of tens of microseconds, hundreds of microseconds, and tens of seconds, respectively.
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35
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Chen AK, Behlke MA, Tsourkas A. Efficient cytosolic delivery of molecular beacon conjugates and flow cytometric analysis of target RNA. Nucleic Acids Res 2008; 36:e69. [PMID: 18503086 PMCID: PMC2475621 DOI: 10.1093/nar/gkn331] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Fluorescent microscopy experiments show that when 2'-O-methyl-modified molecular beacons (MBs) are introduced into NIH/3T3 cells, they elicit a nonspecific signal in the nucleus. This false-positive signal can be avoided by conjugating MBs to macromolecules (e.g. NeutrAvidin) that prevent nuclear sequestration, but the presence of a macromolecule makes efficient cytosolic delivery of these probes challenging. In this study, we explored various methods including TAT peptide, Streptolysin O and microporation for delivering NeutrAvidin-conjugates into the cytosol of living cells. Surprisingly, all of these strategies led to entrapment of the conjugates within lysosomes within 24 h. When the conjugates were pegylated, to help prevent intracellular recognition, only microporation led to a uniform cytosolic distribution. Microporation also yielded a transfection efficiency of 93% and an average viability of 86%. When cells microporated with MB-NeutrAvidin conjugates were examined via flow cytometry, the signal-to-background was found to be more than 3 times higher and the sensitivity nearly five times higher than unconjugated MBs. Overall, the present study introduces an improved methodology for the high-throughput detection of RNA at the single cell level.
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Affiliation(s)
- Antony K Chen
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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36
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Guignet EG, Meyer T. Suspended-drop electroporation for high-throughput delivery of biomolecules into cells. Nat Methods 2008; 5:393-5. [PMID: 18408727 DOI: 10.1038/nmeth.1201] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2007] [Accepted: 03/18/2008] [Indexed: 11/09/2022]
Abstract
We present a high-throughput method that enables efficient delivery of biomolecules into cells. The device consists of an array of 96 suspended electrode pairs, where small sample volumes are top-loaded, electroporated and bottom-ejected into 96-well plates. We demonstrate the use of this suspended-drop electroporation (SDE) device to effectively introduce fluorescent dextran, small interfering RNA (siRNA) or cDNA into primary neurons, differentiated neutrophils and other cell types with conventionally low transfection rates.
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Affiliation(s)
- Emmanuel G Guignet
- Department of Chemical and Systems Biology, Bio-X Program, Clark Center, 318 Campus Drive, Stanford University School of Medicine, Stanford, California 94305, USA.
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37
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Lacayo CI, Pincus Z, VanDuijn MM, Wilson CA, Fletcher DA, Gertler FB, Mogilner A, Theriot JA. Emergence of large-scale cell morphology and movement from local actin filament growth dynamics. PLoS Biol 2007; 5:e233. [PMID: 17760506 PMCID: PMC1951782 DOI: 10.1371/journal.pbio.0050233] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Accepted: 07/03/2007] [Indexed: 12/30/2022] Open
Abstract
Variations in cell migration and morphology are consequences of changes in underlying cytoskeletal organization and dynamics. We investigated how these large-scale cellular events emerge as direct consequences of small-scale cytoskeletal molecular activities. Because the properties of the actin cytoskeleton can be modulated by actin-remodeling proteins, we quantitatively examined how one such family of proteins, enabled/vasodilator-stimulated phosphoprotein (Ena/VASP), affects the migration and morphology of epithelial fish keratocytes. Keratocytes generally migrate persistently while exhibiting a characteristic smooth-edged “canoe” shape, but may also exhibit less regular morphologies and less persistent movement. When we observed that the smooth-edged canoe keratocyte morphology correlated with enrichment of Ena/VASP at the leading edge, we mislocalized and overexpressed Ena/VASP proteins and found that this led to changes in the morphology and movement persistence of cells within a population. Thus, local changes in actin filament dynamics due to Ena/VASP activity directly caused changes in cell morphology, which is coupled to the motile behavior of keratocytes. We also characterized the range of natural cell-to-cell variation within a population by using measurable morphological and behavioral features—cell shape, leading-edge shape, filamentous actin (F-actin) distribution, cell speed, and directional persistence—that we have found to correlate with each other to describe a spectrum of coordinated phenotypes based on Ena/VASP enrichment at the leading edge. This spectrum stretched from smooth-edged, canoe-shaped keratocytes—which had VASP highly enriched at their leading edges and migrated fast with straight trajectories—to more irregular, rounder cells migrating slower with less directional persistence and low levels of VASP at their leading edges. We developed a mathematical model that accounts for these coordinated cell-shape and behavior phenotypes as large-scale consequences of kinetic contributions of VASP to actin filament growth and protection from capping at the leading edge. This work shows that the local effects of actin-remodeling proteins on cytoskeletal dynamics and organization can manifest as global modifications of the shape and behavior of migrating cells and that mathematical modeling can elucidate these large-scale cell behaviors from knowledge of detailed multiscale protein interactions. The shape of animal cells is largely determined by the organization of their internal structural elements, including the filamentous structures of their cytoskeleton. Motile cells that crawl across solid substrates must assemble their cytoskeletal actin filaments in a spatially organized way, such that net filament growth and cell protrusion occur at the front of the cell. Actin filament dynamics, in turn, influence the overall shape of the cell by pushing on the plasma membrane. In this work, we have explored the ways that variations in small-scale actin filament growth dynamics are coupled to large-scale changes in cell shape and behavior. By manipulating the availability of a family of actin-binding proteins (Ena/VASP) that regulate actin filament growth, we can alter the overall cell shape and motile behavior of epithelial fish keratocytes—unusually fast-moving and regularly shaped cells. We have also found that unperturbed keratocytes in a population exhibit a continuum of shape and behavioral variations that can be correlated with differences in Ena/VASP levels. We have developed a mathematical model that allows us to explain our observations of intrinsic cell-to-cell shape variation, motile behavior, and cell responses to molecular perturbations as a function of actin filament growth dynamics in motile cells. Mathematical modeling predicts global modifications of the shape and behavior of migrating cells from knowledge of detailed multiscale protein interactions.
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Affiliation(s)
- Catherine I Lacayo
- Department of Biochemistry, Stanford University, Stanford, California, United States of America
| | - Zachary Pincus
- Department of Biochemistry, Stanford University, Stanford, California, United States of America
- Program in Biomedical Informatics, Stanford University, Stanford, California, United States of America
| | - Martijn M VanDuijn
- Department of Bioengineering, University of California, Berkeley, California, United States of America
| | - Cyrus A Wilson
- Department of Biochemistry, Stanford University, Stanford, California, United States of America
| | - Daniel A Fletcher
- Department of Bioengineering, University of California, Berkeley, California, United States of America
| | - Frank B Gertler
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Alex Mogilner
- Department of Neurobiology, Physiology and Behavior, University of California Davis, Davis, California, United States of America
- Department of Mathematics, University of California Davis, Davis, California, United States of America
| | - Julie A Theriot
- Department of Biochemistry, Stanford University, Stanford, California, United States of America
- Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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38
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Yam PT, Wilson CA, Ji L, Hebert B, Barnhart EL, Dye NA, Wiseman PW, Danuser G, Theriot JA. Actin-myosin network reorganization breaks symmetry at the cell rear to spontaneously initiate polarized cell motility. ACTA ACUST UNITED AC 2007; 178:1207-21. [PMID: 17893245 PMCID: PMC2064654 DOI: 10.1083/jcb.200706012] [Citation(s) in RCA: 189] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have analyzed the spontaneous symmetry breaking and initiation of actin-based motility in keratocytes (fish epithelial cells). In stationary keratocytes, the actin network flow was inwards and radially symmetric. Immediately before motility initiation, the actin network flow increased at the prospective cell rear and reoriented in the perinuclear region, aligning with the prospective axis of movement. Changes in actin network flow at the cell front were detectable only after cell polarization. Inhibition of myosin II or Rho kinase disrupted actin network organization and flow in the perinuclear region and decreased the motility initiation frequency, whereas increasing myosin II activity with calyculin A increased the motility initiation frequency. Local stimulation of myosin activity in stationary cells by the local application of calyculin A induced directed motility initiation away from the site of stimulation. Together, these results indicate that large-scale actin–myosin network reorganization and contractility at the cell rear initiate spontaneous symmetry breaking and polarized motility of keratocytes.
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Affiliation(s)
- Patricia T Yam
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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39
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Ye H, Cotic M, Carlen PL. Transmembrane potential induced in a spherical cell model under low-frequency magnetic stimulation. J Neural Eng 2007; 4:283-93. [PMID: 17873431 DOI: 10.1088/1741-2560/4/3/014] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Time-varying magnetic fields can induce electric fields in the neuronal tissue, a phenomenon that has been recently explored in clinical applications such as peripheral nerve stimulation and transcranial magnetic stimulation. Although the transmembrane potential induced during direct electric stimulation has already been the subject of a number of theoretical studies, an analytical solution for the magnetically induced transmembrane potential change is still unavailable. In addition, although several studies have analyzed the impact of stimulation parameters, including stimulation intensity and frequency, as well as coil design and position, on the amount of tissue polarization, the effects of tissue non-homogeneity on cell polarization have not been fully elucidated. In this study, we have derived an analytical expression for the transmembrane potential induced by a low-frequency magnetic field in a spherical neuronal structure. This model is representative of a spherical cell body or any neuronal structure of a similar shape. The model cell is located in an extracellular medium and possesses a low-conductive membrane and an internal cytoplasm. These three regions represent the basic tissue non-homogeneity of a neuron at a microscopic level. The sensitivity of the induced transmembrane potential to the coil position and to the geometrical and electrical parameters of the model structure was studied in a broad physiologically relevant range. Our results demonstrate that the structure is regionally polarized, with the pattern of polarization depending on the relative positioning between the model cell and the stimulation coil. In addition, both the geometrical and electrical parameters of the structure affect the amount of polarization. These results may be generalized to other neuronal tissues that possess similar non-homogenous properties, but different shapes, such as an axon. Our results support the idea that aside from coil design and position, tissue non-homogeneity could play an important role in determining the effects of magnetic stimulation.
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Affiliation(s)
- Hui Ye
- Toronto Western Research Institute, University Health Network, Toronto, Ontario M5T 2S8, Canada.
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40
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Olofsson J, Levin M, Strömberg A, Weber SG, Ryttsén F, Orwar O. Scanning electroporation of selected areas of adherent cell cultures. Anal Chem 2007; 79:4410-8. [PMID: 17511419 DOI: 10.1021/ac062140i] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a computer-controlled scanning electroporation method. Adherent cells are electroporated using an electrolyte-filled capillary in contact with an electrode. The capillary can be scanned over a cell culture and locally deliver both an electric field and an electroporation agent to the target area without affecting surrounding cells. The instantaneous size of the targeted area is determined by the dimensions of the capillary. The size and shape of the total electroporated area are defined by these dimensions in combination with the scanning pattern. For example, striped and serpentine patterns of electroporated cells in confluent cultures can be formed. As it is easy to switch between different electroporation agents, the method is suitable for design of cell cultures with complex composition. Finite element method simulations were used to study the spatial distributions of the electric field and the concentration of an electroporation agent, as well as the fluid dynamics related to scanning and flow of electroporation agent from the capillary. The method was validated for transfection by introduction of a 9-base-pair-long randomized oligonucleotide into PC12 cells and a pmaxGFP plasmid coding for green fluorescent protein into CHO and WSS cells.
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Affiliation(s)
- Jessica Olofsson
- Department of Physical Chemistry, Chalmers University of Technology, Kemivägen 10, SE-412 96 Gothenburg, Sweden
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41
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Khine M, Ionescu-Zanetti C, Blatz A, Wang LP, Lee LP. Single-cell electroporation arrays with real-time monitoring and feedback control. LAB ON A CHIP 2007; 7:457-62. [PMID: 17389961 DOI: 10.1039/b614356c] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Rapid well-controlled intracellular delivery of drug compounds, RNA, or DNA into a cell--without permanent damage to the cell--is a pervasive challenge in basic cell biology research, drug discovery, and gene delivery. To address this challenge, we have developed a bench-top system comprised of a control interface, that mates to disposable 96-well-formatted microfluidic devices, enabling the individual manipulation, electroporation and real-time monitoring of each cell in suspension. This is the first demonstrated real-time feedback-controlled electroporation of an array of single-cells. Our computer program automatically detects electroporation events and subsequently releases the electric field, precluding continued field-induced damage of the cell, to allow for membrane resealing. Using this novel set-up, we demonstrate the reliable electroporation of an array (n = 15) of individual cells in suspension, using low applied electric fields (<1 V) and the rapid and localized intracellular delivery of otherwise impermeable compounds (Calcein and Orange Green Dextran). Such multiplexed electrical and optical measurements as a function of time are not attainable with typical electroporation setups. This system, which mounts on an inverted microscope, obviates many issues typically associated with prototypical microfluidic chip setups and, more importantly, offers well-controlled and reproducible parallel pressure and electrical application to individual cells for repeatability.
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Affiliation(s)
- Michelle Khine
- School of Engineering, University of California, Merced, CA, USA.
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42
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Nevian T, Helmchen F. Calcium indicator loading of neurons using single-cell electroporation. Pflugers Arch 2007; 454:675-88. [PMID: 17334778 DOI: 10.1007/s00424-007-0234-2] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 01/15/2007] [Accepted: 02/12/2007] [Indexed: 12/26/2022]
Abstract
Studies of subcellular Ca(2+) signaling rely on methods for labeling cells with fluorescent Ca(2+) indicator dyes. In this study, we demonstrate the use of single-cell electroporation for Ca(2+) indicator loading of individual neurons and small neuronal networks in rat neocortex in vitro and in vivo. Brief voltage pulses were delivered through glass pipettes positioned close to target cells. This approach resulted in reliable and rapid (within seconds) loading of somata and subsequent complete labeling of dendritic and axonal arborizations. By using simultaneous whole-cell recordings in brain slices, we directly addressed the effect of electroporation on neurons. Cell viability was high (about 85%) with recovery from the membrane permeabilization occurring within a minute. Electrical properties of recovered cells were indistinguishable before and after electroporation. In addition, Ca(2+) transients with normal appearance could be evoked in dendrites, spines, and axonal boutons of electroporated cells. Using negative-stains of somata, targeted single-cell electroporation was equally applicable in vivo. We conclude that electroporation is a simple approach that permits Ca(2+) indicator loading of multiple cells with low background staining within a short amount of time, which makes it especially well suited for functional imaging of subcellular Ca(2+) dynamics in small neuronal networks.
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Affiliation(s)
- Thomas Nevian
- Abteilung Zellphysiologie, Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
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43
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Lovell P, Jezzini SH, Moroz LL. Electroporation of neurons and growth cones in Aplysia californica. J Neurosci Methods 2006; 151:114-20. [PMID: 16174534 DOI: 10.1016/j.jneumeth.2005.06.030] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 06/24/2005] [Accepted: 06/24/2005] [Indexed: 11/19/2022]
Abstract
Specific labeling of individual neurons and neuronal processes is virtually an everyday task for neuroscientists. Many traditional ways for delivery of intracellular dyes have limitations in terms of speed, efficiency and reproducibility. Electroporation is a fast, reliable and efficient method to deliver microscopic amounts of polar and charged molecules into neurons and their compartments such as individual neurites and growth cones. Here, we present a simple and highly effective procedure for intracellular labeling of individual Aplysia neurons both in intact ganglia and in cell culture. Pleural mechanoreceptor neurons have been used as illustrative examples to demonstrate applicability of direct and local labeling of the smallest individual neurites (< 2 microm) and single growth cones. Specifically, a 3-s train of 1.0 V hyperpolarizing pulses at 50 Hz effectively filled discrete neurites in contact with the tip of the micropipette with no dye transfer visible to other, non-contacted neurites. Application of this localized dye labeling technique to single neurites reveals a surprisingly complex morphology for patterns of axonal branching in culture. The protocol can be easily applied to a variety of models in neuroscience including accessible nervous systems of invertebrate animals.
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Affiliation(s)
- Peter Lovell
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9005 Ocean Shore Blvd., St. Augustine, FL 32080, USA
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44
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Thore S, Dyachok O, Gylfe E, Tengholm A. Feedback activation of phospholipase C via intracellular mobilization and store-operated influx of Ca2+ in insulin-secreting β-cells. J Cell Sci 2005; 118:4463-71. [PMID: 16159958 DOI: 10.1242/jcs.02577] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Phospholipase C (PLC) regulates various cellular processes by catalyzing the formation of inositol-1,4,5-trisphosphate (IP3) and diacylglycerol from phosphatidylinositol-4,5-bisphosphate (PIP2). Here, we have investigated the influence of Ca2+ on receptor-triggered PLC activity in individual insulin-secreting β-cells. Evanescent wave microscopy was used to record PLC activity using green fluorescent protein (GFP)-tagged PIP2/IP3-binding pleckstrin homology domain from PLCδ1, and the cytoplasmic Ca2+ concentration ([Ca2+]i) was simultaneously measured using the indicator Fura Red. Stimulation of MIN6 β-cells with the muscarinic-receptor agonist carbachol induced rapid and sustained PLC activation. By contrast, only transient activation was observed after stimulation in the absence of extracellular Ca2+ or in the presence of the non-selective Ca2+ channel inhibitor La3+. The Ca2+-dependent sustained phase of PLC activity did not require voltage-gated Ca2+ influx, as hyperpolarization with diazoxide or direct Ca2+ channel blockade with nifedipine had no effect. Instead, the sustained PLC activity was markedly suppressed by the store-operated channel inhibitors 2-APB and SKF96365. Depletion of intracellular Ca2+ stores with the sarco(endo)plasmic reticulum Ca2+-ATPase inhibitors thapsigargin or cyclopiazonic acid abolished Ca2+ mobilization in response to carbachol, and strongly suppressed the PLC activation in Ca2+-deficient medium. Analogous suppressions were observed after loading cells with the Ca2+ chelator BAPTA. Stimulation of primary mouse pancreatic β-cells with glucagon elicited pronounced [Ca2+]i spikes, reflecting protein kinase A-mediated activation of Ca2+-induced Ca2+ release via IP3 receptors. These [Ca2+]i spikes were found to evoke rapid and transient activation of PLC. Our data indicate that receptor-triggered PLC activity is enhanced by positive feedback from Ca2+ entering the cytoplasm from intracellular stores and via store-operated channels in the plasma membrane. Such amplification of receptor signalling should be important in the regulation of insulin secretion by hormones and neurotransmitters.
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Affiliation(s)
- Sophia Thore
- Department of Medical Cell Biology, Uppsala University, Biomedical Centre, Box 571, SE-75123 Uppsala, Sweden
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45
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Valic B, Pavlin M, Miklavcic D. The effect of resting transmembrane voltage on cell electropermeabilization: a numerical analysis. Bioelectrochemistry 2004; 63:311-5. [PMID: 15110294 DOI: 10.1016/j.bioelechem.2003.12.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2003] [Revised: 12/09/2003] [Accepted: 12/11/2003] [Indexed: 10/26/2022]
Abstract
The transmembrane voltage induced due to applied electric field superimposes to the resting transmembrane voltage of the cell. On the part of the cell membrane, where the transmembrane voltage exceeds the threshold transmembrane voltage, changes in the membrane occur, leading to increase in membrane permeability known as electropermeabilization. This part of the cell membrane represents the permeabilized area through which the transport of molecules occurs. In this paper we calculated numerically the permeabilized area for different electric field strength, resting transmembrane voltage, cell shape and cell orientation with respect to the applied electric field. Results show that when the transmembrane voltage is near the threshold transmembrane voltage, the permeabilized area of the cell is increased on the anodic side and decreased on the cathodic side due to the resting transmembrane voltage. In some cases, only anodic side of the cell is permeabilized. Therefore, by using bipolar pulses, the permeabilized area can be significantly increased and consequentially also the efficiency of electropermeabilization. However, when the induced transmembrane voltage is far above the threshold, the effect of the resting transmembrane voltage is negligible. These observations are valid for different cell shapes and orientations.
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Affiliation(s)
- Blaz Valic
- Faculty of Electrical Engineering, University of Ljubljana, Trzaska 25, SI-1000 Ljubljana, Slovenia
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46
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Thorogate R, Török K. Ca2+-dependent and -independent mechanisms of calmodulin nuclear translocation. J Cell Sci 2004; 117:5923-36. [PMID: 15522886 DOI: 10.1242/jcs.01510] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Translocation from the cytosol to the nucleus is a major response by calmodulin (CaM) to stimulation of cells by Ca2+. However, the mechanisms involved in this process are still controversial and both passive and facilitated diffusion have been put forward. We tested nuclear translocation mechanisms in electroporated HeLa cells, rat cortical neurons and glial cells using novel calmodulin and inhibitor peptide probes and confocal microscopy. Passive diffusion of calmodulin across the nuclear membrane was measured in conditions in which facilitated transport was blocked and was compared to that of a similarly sized fluorescein-labeled dextran. Wheat germ agglutinin, which blocks facilitated transport but not passive diffusion, inhibited the nuclear entry of both wild-type and Ca2+-binding-deficient mutant calmodulin both in low and elevated [Ca2+]. Ca2+-dependent nuclear translocation was prevented by a membrane-permeant CaM inhibitor, the mTrp peptide, which indicated that it was specific to Ca2+/CaM. Diffusion of free CaM and Ca2+/CaM was considerably slower than the observed nuclear translocation by facilitated transport. Our data show that the majority of CaM nuclear entry occurred by facilitated mechanisms in all cell types examined, in part by a Ca2+-independent and in part by a Ca2+-dependent translocation mechanism.
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Affiliation(s)
- Richard Thorogate
- Department of Basic Medical Sciences, St Georges Hospital Medical School, Cranmer Terrace, London, SW17 0RE, UK
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47
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Baryza JL, Brenner SE, Craske ML, Meyer T, Wender PA. Simplified Analogs of Bryostatin with Anticancer Activity Display Greater Potency for Translocation of PKCδ-GFP. ACTA ACUST UNITED AC 2004; 11:1261-7. [PMID: 15380186 DOI: 10.1016/j.chembiol.2004.06.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2004] [Revised: 06/21/2004] [Accepted: 06/28/2004] [Indexed: 11/19/2022]
Abstract
Structurally simplified analogs of bryostatin 1, a marine natural product in clinical trials for the treatment of cancer, have been shown to be up to 50 times more potent than bryostatin 1 at inducing the translocation of PKCdelta-GFP from the cytosol of rat basophilic leukemia (RBL) cells. The end distribution of the protein is similar for all three compounds, despite a significant difference in translocation kinetics. The potency of the compounds for inducing the translocation response appears to be only qualitatively related to their binding affinity for PKC, highlighting the importance of using binding affinity in conjunction with real-time measurements of protein localization for the pharmacological profiling of biologically active agents.
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Affiliation(s)
- Jeremy L Baryza
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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48
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Guyenet PG, Stornetta RL, Weston MC, McQuiston T, Simmons JR. Detection of amino acid and peptide transmitters in physiologically identified brainstem cardiorespiratory neurons. Auton Neurosci 2004; 114:1-10. [PMID: 15331039 DOI: 10.1016/j.autneu.2004.06.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 06/15/2004] [Accepted: 06/17/2004] [Indexed: 10/26/2022]
Abstract
Most of the CNS neurons that regulate circulation and respiration reside in regions of the brain characterized by extreme cellular heterogeneity (nucleus of the solitary tract, reticular formation, parabrachial nuclei, periaqueductal gray matter, hypothalamus, etc.). The chemical neuroanatomy of these regions is correspondingly complex and teasing out specific circuits in their midst remains a problem that is usually very difficult if not impossible to solve by conventional tract-tracing methods, Fos methodology or electrophysiology in slices. In addition, identifying the type of amino acid or peptide transmitter used by electrophysiologically recorded neurons has been until recently an especially difficult task either for lack of a specific marker or because such markers (many peptides for example) are exported to synaptic terminals and thus undetectable in neuronal cell bodies. In this review, we describe a general purpose method that solves many of these problems. The approach combines juxtacellular labeling in vivo with the histological identification of mRNAs that provide definitive neurochemical phenotypic identification (e.g. vesicular glutamate transporter 1 or 2, glutamic acid decarboxylase). The results obtained with this method are discussed in the general context of amino acid transmission in brainstem cardiorespiratory pathways. The presence of markers of amino acid transmission in specific aminergic pre-sympathetic neurons is especially emphasized as is the extensive co-localization of markers of GABAergic and glycinergic transmission in the brainstem reticular formation.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, United States
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49
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Geddes DM, Cargill RS, LaPlaca MC. Mechanical stretch to neurons results in a strain rate and magnitude-dependent increase in plasma membrane permeability. J Neurotrauma 2004; 20:1039-49. [PMID: 14588120 DOI: 10.1089/089771503770195885] [Citation(s) in RCA: 143] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mechanism by which mechanical impact to brain tissue is transduced to neuronal impairment remains poorly understood. Using an in vitro model of neuronal stretch, we found that mechanical stretch of neurons resulted in a transient plasma membrane permeability increase. Primary cortical neurons, seeded on silicone substrates, were subjected to a defined rate and magnitude strain pulse by stretching the substrates over a fixed cylindrical form. To identify plasma membrane defects, various sized fluorescent molecules were added to the bathing media either immediately before injury or 1, 2, 5, or 10 min after injury and removed one minute later. The percent of cells that took up dye depended on the applied strain rate, strain magnitude and molecular size. Severe stretch (10 sec(-1), 0.30) resulted in significant uptake of all tested molecules (ranging between 0.5 and 8.9 nm radii) with up to 60% of cells positively stained. Furthermore, the neurons remained permeable to the smallest molecule (carboxyfluorescein, 380 Da) up to 5 min after severe stretch but were only permeable to larger molecules (>/=10 kDa) immediately after stretch. These transiently formed membrane defects may be the initiating mechanism that translates mechanical stretch to cellular dysfunction.
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Affiliation(s)
- Donna M Geddes
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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50
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Han F, Wang Y, Sims CE, Bachman M, Chang R, Li GP, Allbritton NL. Fast Electrical Lysis of Cells for Capillary Electrophoresis. Anal Chem 2003; 75:3688-96. [PMID: 14572031 DOI: 10.1021/ac0341970] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In the past decade, capillary electrophoresis has demonstrated increasing utility for the quantitative analysis of single cells. New applications for the analysis of dynamic cellular properties demand sampling methods with sufficient temporal resolution to accurately measure these processes. In particular, intracellular signaling pathways involving many enzymes can be modulated on subsecond time scales. We have developed a technique to rapidly lyse an adherent mammalian cell using a single electrical pulse followed by efficient loading of the cellular contents into a capillary. Microfabricated electrodes were designed to create a maximum voltage drop across the flattened cell's plasma membrane at a minimum interelectrode voltage. The influence of the interelectrode distance, pulse duration, and pulse strength on the rate of cell lysis was determined. The ability to rapidly lyse a cell and collect and separate the cellular contents was demonstrated by loading cells with Oregon Green and two isomers of carboxyfluorescein. All three fluorophores were detected with a separation efficiency comparable to that of standards. Parallel comparison of electrical lysis to that produced by a laser-based lysis system revealed that the sampling efficiencies of the two techniques were comparable. Rapid cell lysis by an electrical pulse may increase the application of capillary electrophoresis to the study of cellular dynamics requiring fast sampling times.
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Affiliation(s)
- Futian Han
- Department of Physiology and Biophysics, University of California, Irvine, California 92697, USA
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