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Luo KH, Chen RD, Hsu CH, Li WT, Yan M, Chin TY, Yeh JM. Effect of Sulfonation Group on Polyaniline Copolymer Scaffolds for Tissue Engineering with Laminin Treatment under Electrical Stimulation. ACS APPLIED BIO MATERIALS 2022; 5:3778-3787. [PMID: 35831781 DOI: 10.1021/acsabm.2c00323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sulfonated copolyanilines (SPANs), SPAN-40 and SPAN-75, were prepared and applied in this tissue engineering study. SPAN scaffolds (SPANs) and control group polyaniline (PANI) were synthesized by performing oxidative polymerization. To further research the effects of neuron regeneration, PC12 cells were cultured on as-prepared PANI and SPANs with laminin (La) treatment under electrical stimulation. The effects on PC12 cell differentiation were investigated by controlling the amount of sulfonated groups (-SO3H) in the SPAN chain, the electrical stimulation voltage, and the presence or absence of La coating. The adhesion and proliferation of cells increased with the degree of sulfonation; La and electrical stimulation further promoted neuronal cell differentiation as increased neurite length was demonstrated in the micrograph analyses. In summary, the sulfonated copolyaniline coated with La had the best effect on neuronal differentiation under electrical stimulation, suggesting its potential as a substrate for nerve tissue engineering.
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Affiliation(s)
- Kun-Hao Luo
- Department of Chemistry, R & D Center for Membrane Technology at Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
| | - Rui-Da Chen
- Department of Chemistry, R & D Center for Membrane Technology at Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
| | - Chien-Hua Hsu
- Department of Chemistry, R & D Center for Membrane Technology at Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
| | - Wen-Tyng Li
- Department of Biomedical Engineering, Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
| | - Minsi Yan
- Department of Chemistry, R & D Center for Membrane Technology at Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
| | - Ting-Yu Chin
- Department of Bioscience Technology, Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
| | - Jui-Ming Yeh
- Department of Chemistry, R & D Center for Membrane Technology at Chung Yuan Christian University, Chung Li, Taiwan 32023, Republic of China
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2
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Application of stable continuous external electric field promotes wound healing in pig wound model. Bioelectrochemistry 2020; 135:107578. [DOI: 10.1016/j.bioelechem.2020.107578] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 05/25/2020] [Accepted: 05/31/2020] [Indexed: 12/13/2022]
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3
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Zhao Y, Peng HB. Roles of tyrosine kinases and phosphatases in the formation and dispersal of acetylcholine receptor clusters. Neurosci Lett 2020; 733:135054. [PMID: 32428606 DOI: 10.1016/j.neulet.2020.135054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 05/09/2020] [Accepted: 05/12/2020] [Indexed: 10/24/2022]
Abstract
The formation of acetylcholine receptor (AChR) clusters at the postsynaptic muscle membrane in response to motor innervation is a key event in the development of the neuromuscular junction. The synaptic AChR clustering process is initiated by motor axon-released agrin, which activates a tyrosine kinase-based signaling pathway to cause AChR aggregation. In cultured muscle cells, AChR clustering is elicited by diverse nonneural signals, and this process is also mediated by tyrosine kinases. Conversely, the formation of new AChR clusters induced by innervation or nonneural stimuli is unfailingly associated with the dispersal of pre-existing AChR clusters, and this process is mediated by tyrosine phosphatases. In this review, we address how local kinase activation leads to global phosphatase action in muscle. More specifically, we discuss the roles of Src kinase and the SH2 domain-containing tyrosine phosphatase Shp-2 in establishing a regenerative mechanism to propagate the AChR cluster dispersing signal extrasynaptically and in defining the boundary of cluster formation subsynaptically.
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Affiliation(s)
- Yang Zhao
- Division of Life Science, the Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region.
| | - H Benjamin Peng
- Division of Life Science, the Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong Special Administrative Region; College of Life Science, National Tsing Hua University, Hsinchu, Taiwan, ROC.
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4
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Zhao H, Liu M, Zhang Y, Yin J, Pei R. Nanocomposite hydrogels for tissue engineering applications. NANOSCALE 2020; 12:14976-14995. [PMID: 32644089 DOI: 10.1039/d0nr03785k] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Tissue engineering is an important field of regenerative medicine, which combines scaffolds and cell transplantation to develop substitute tissues and/or promote tissue regeneration. Hydrogels, a three-dimensional network with high water content and biocompatibility, have been widely used as scaffolds to mimic the structure and properties of tissues. However, the low mechanical strength and limited functions of traditional hydrogels greatly limited their applications in tissue engineering. Recently, nanocomposite hydrogels, with its advantages of high mechanical property and some unique properties (such as electrical conductivity, antibacterial, antioxidation, magnetic responsiveness), have emerged as the most versatile and innovative technology, which provides a new opportunity as a unique tool for fabricating hydrogels with excellent properties. In this review, we summarize the recent advances in fabricating nanocomposite hydrogels and their applications in tissue engineering. In addition, the future and prospects of nanocomposite hydrogels for tissue engineering are also discussed.
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Affiliation(s)
- Hongbo Zhao
- Department of Polymer Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China and CAS Key Laboratory for Nano-Bio Interface, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
| | - Min Liu
- Institute for Interdisciplinary Research, Jianghan University, Wuhan 430056, China
| | - Yajie Zhang
- CAS Key Laboratory for Nano-Bio Interface, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
| | - Jingbo Yin
- Department of Polymer Materials, School of Materials Science and Engineering, Shanghai University, Shanghai 200444, China
| | - Renjun Pei
- CAS Key Laboratory for Nano-Bio Interface, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, China.
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5
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Sarvari R, Massoumi B, Zareh A, Beygi-Khosrowshahi Y, Agbolaghi S. Porous conductive and biocompatible scaffolds on the basis of polycaprolactone and polythiophene for scaffolding. Polym Bull (Berl) 2019. [DOI: 10.1007/s00289-019-02732-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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6
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Hart FX, Palisano JR. Glycocalyx bending by an electric field increases cell motility. Bioelectromagnetics 2017; 38:482-493. [PMID: 28543319 DOI: 10.1002/bem.22060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 04/19/2017] [Indexed: 01/02/2023]
Abstract
The application of physiological strength electric fields may produce a wide range of effects on cells. The mechanisms by which cells detect the presence of these fields, however, are not fully understood. Previous experiments have shown that directionality of cells in the field is governed by an electromechanical mechanism in which the field exerts a torque on the negatively charged, inner glycocalyx that is then transmitted as a force on the cytoskeleton. This mechanism is similar to that by which cells detect fluid shear forces. Several authors, however, have reported that cell directionality and motility behave differently in an electric field. We propose here a second electromechanical mechanism in which the field bends the negatively charged, outer glycocalyx in proximity to the substrate, increasing cell adhesion and, thus, cell motility. The increase in motility depends not only on the field strength, but also on the adhesion of the cell to the substrate prior to application of the field. We show that these mechanisms are common to both human cells and amoebae and, hence, are evolutionarily conserved. Furthermore, the mechanism for detection of electric fields is simply an extension of the mechanism for detecting fluid shears. Bioelectromagnetics. 38:482-493, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Francis X Hart
- Department of Physics, The University of the South, Sewanee, Tennessee
| | - John R Palisano
- Department of Biology, The University of the South, Sewanee, Tennessee
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7
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Ross CL. The use of electric, magnetic, and electromagnetic field for directed cell migration and adhesion in regenerative medicine. Biotechnol Prog 2016; 33:5-16. [PMID: 27797153 DOI: 10.1002/btpr.2371] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Revised: 10/10/2016] [Indexed: 01/01/2023]
Abstract
Directed cell migration and adhesion is essential to embryonic development, tissue formation and wound healing. For decades it has been reported that electric field (EF), magnetic field (MF) and electromagnetic field (EMF) can play important roles in determining cell differentiation, migration, adhesion, and evenwound healing. Combinations of these techniques have revealed new and exciting explanations for how cells move and adhere to surfaces; how the migration of multiple cells are coordinated and regulated; how cellsinteract with neighboring cells, and also to changes in their microenvironment. In some cells, speed and direction are voltage dependent. Data suggests that the use of EF, MF and EMF could advance techniques in regenerative medicine, tissue engineering and wound healing. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:5-16, 2017.
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Affiliation(s)
- Christina L Ross
- The Wake Forest Institute for Regenerative Medicine, Wake Forest Center for Integrative Medicine, Medical Center Blvd, Winston-Salem, NC
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8
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Pulsed electrical stimulation benefits wound healing by activating skin fibroblasts through the TGFβ1/ERK/NF-κB axis. Biochim Biophys Acta Gen Subj 2016; 1860:1551-9. [DOI: 10.1016/j.bbagen.2016.03.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 02/26/2016] [Accepted: 03/20/2016] [Indexed: 02/06/2023]
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9
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Wang X, Gao Y, Shi H, Liu N, Zhang W, Li H. Influence of the intensity and loading time of direct current electric field on the directional migration of rat bone marrow mesenchymal stem cells. Front Med 2016; 10:286-96. [PMID: 27324024 DOI: 10.1007/s11684-016-0456-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 05/05/2016] [Indexed: 10/21/2022]
Abstract
Exogenic electric fields can effectively accelerate bone healing and remodeling through the enhanced migration of bone marrow mesenchymal stem cells (BMSCs) toward the injured area. This study aimed to determine the following: (1) the direction of rat BMSC (rBMSC) migration upon exposure to a direct current electric field (DCEF), (2) the optimal DCEF intensity and duration, and (3) the possible regulatory role of SDF-1/CXCR4 axis in rBMSC migration as induced by DCEF. Results showed that rBMSCs migrated to the positive electrode of the DCEF, and that the DCEF of 200 mV/mm for 4 h was found to be optimal in enhancing rBMSC migration. This DCEF strength and duration also upregulated the expression of osteoblastic genes, including ALP and OCN, and upregulated the expression of ALP and Runx2 proteins. Moreover, when CXCR4 was inhibited, rBMSC migration due to DCEF was partially blocked. These findings indicated that DCEF can effectively induce rBMSC migration. A DCEF of 200 mV/mm for 4 h was recommended because of its ability to promote rBMSC migration, proliferation, and osteogenic differentiation. The SDF-1/CXCR4 signaling pathway may play an important role in regulating the DCEF-induced migration of rBMSCs.
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Affiliation(s)
- Xiaoyu Wang
- Department of Stomatology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Yuxuan Gao
- Department of Stomatology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Haigang Shi
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Na Liu
- Department of Stomatology, Chinese PLA General Hospital, Beijing, 100853, China
| | - Wei Zhang
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Hongbo Li
- Department of Stomatology, Chinese PLA General Hospital, Beijing, 100853, China.
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10
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Riding A, Pullar CE. ATP Release and P2 Y Receptor Signaling are Essential for Keratinocyte Galvanotaxis. J Cell Physiol 2016; 231:181-91. [PMID: 26058714 DOI: 10.1002/jcp.25070] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 06/05/2015] [Indexed: 01/06/2023]
Abstract
Repair to damaged tissue requires directional cell migration to heal the wound. Immediately upon wounding an electrical guidance cue is created with the cathode of the electric field (EF) located at the center of the wound. Previous research has demonstrated directional migration of keratinocytes toward the cathode when an EF of physiological strength (100-150 mV/mm) is applied in vitro, but the "sensor" by which keratinocytes sense the EF remains elusive. Here we use a customized chamber design to facilitate the application of a direct current (DC) EF of physiological strength (100 mV/mm) to keratinocytes whilst pharmacologically modulating the activation of both connexin hemichannels and purinergic receptors to determine their role in EF-mediated directional keratinocyte migration, galvanotaxis. In addition, keratinocytes were exposed to DiSCAC2 (3) dye to visualize membrane potential changes within the cell upon exposure to the applied DC EF. Here we unveil ATP-medicated mechanisms that underpin the initiation of keratinocyte galvanotaxis. The application of a DC EF of 100 mV/mm releases ATP via hemichannels activating a subset of purinergic P2 Y receptors, locally, to initiate the directional migration of keratinocytes toward the cathode in vitro, the center of the wound in vivo. The delineation of the mechanisms underpinning galvanotaxis extends our understanding of this endogenous cue and will facilitate the optimization and wider use of EF devices for chronic wound treatment. J. Cell. Physiol. 230: 181-191, 2016. © 2015 Wiley Periodicals, Inc.
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Affiliation(s)
- Aimie Riding
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK
| | - Christine E Pullar
- Department of Cell Physiology and Pharmacology, University of Leicester, Leicester, UK
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11
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Zhu K, Sun Y, Miu A, Yen M, Liu B, Zeng Q, Mogilner A, Zhao M. cAMP and cGMP Play an Essential Role in Galvanotaxis of Cell Fragments. J Cell Physiol 2015; 231:1291-300. [PMID: 26517849 DOI: 10.1002/jcp.25229] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 10/28/2015] [Indexed: 01/09/2023]
Abstract
Cell fragments devoid of the nucleus and major organelles are found in physiology and pathology, for example platelets derived from megakaryocytes, and cell fragments from white blood cells and glioma cells. Platelets exhibit active chemotaxis. Fragments from white blood cells display chemotaxis, phagocytosis, and bactericidal functions. Signaling mechanisms underlying migration of cell fragments are poorly understood. Here we used fish keratocyte fragments and demonstrated striking differences in signal transduction in migration of cell fragments and parental cells in a weak electric field. cAMP or cGMP agonists completely abolished directional migration of fragments, but had no effect on parental cells. The inhibition effects were prevented by pre-incubating with cAMP and cGMP antagonists. Blocking cAMP and cGMP downstream signaling by inhibition of PKA and PKG also recovered fragment galvanotaxis. Both perturbations confirmed that the inhibitory effect was mediated by cAMP or cGMP signaling. Inhibition of cathode signaling with PI3K inhibitor LY294002 also prevented the effects of cAMP or cGMP agonists. Our results suggest that cAMP and cGMP are essential for galvanotaxis of cell fragments, in contrast to the signaling mechanisms in parental cells.
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Affiliation(s)
- Kan Zhu
- Departments of Dermatology and Ophthalmology, Institute for Regenerative Cures, University of California Davis School of Medicine, Sacramento, California.,Bioelectromagnetics Laboratory, Zhejiang University School of Medicine, Hangzhou, China
| | - Yaohui Sun
- Departments of Dermatology and Ophthalmology, Institute for Regenerative Cures, University of California Davis School of Medicine, Sacramento, California
| | - Anh Miu
- Departments of Dermatology and Ophthalmology, Institute for Regenerative Cures, University of California Davis School of Medicine, Sacramento, California
| | - Michael Yen
- Departments of Dermatology and Ophthalmology, Institute for Regenerative Cures, University of California Davis School of Medicine, Sacramento, California
| | - Bowei Liu
- Departments of Dermatology and Ophthalmology, Institute for Regenerative Cures, University of California Davis School of Medicine, Sacramento, California
| | - Qunli Zeng
- Bioelectromagnetics Laboratory, Zhejiang University School of Medicine, Hangzhou, China
| | - Alex Mogilner
- Courant Institute and Department of Biology, New York University, New York, New York
| | - Min Zhao
- Departments of Dermatology and Ophthalmology, Institute for Regenerative Cures, University of California Davis School of Medicine, Sacramento, California
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12
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Peitzman ER, Zaidman NA, Maniak PJ, O'Grady SM. Agonist binding to β-adrenergic receptors on human airway epithelial cells inhibits migration and wound repair. Am J Physiol Cell Physiol 2015; 309:C847-55. [PMID: 26491049 DOI: 10.1152/ajpcell.00159.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 10/19/2015] [Indexed: 12/30/2022]
Abstract
Human airway epithelial cells express β-adrenergic receptors (β-ARs), which regulate mucociliary clearance by stimulating transepithelial anion transport and ciliary beat frequency. Previous studies using airway epithelial cells showed that stimulation with isoproterenol increased cell migration and wound repair by a cAMP-dependent mechanism. In the present study, impedance-sensing arrays were used to measure cell migration and epithelial restitution following wounding of confluent normal human bronchial epithelial (NHBE) and Calu-3 cells by electroporation. Stimulation with epinephrine or the β2-AR-selective agonist salbutamol significantly delayed wound closure and reduced the mean surface area of lamellipodia protruding into the wound. Treatment with the β-AR bias agonist carvedilol or isoetharine also produced a delay in epithelial restitution similar in magnitude to epinephrine and salbutamol. Measurements of extracellular signal-regulated kinase phosphorylation following salbutamol or carvedilol stimulation showed no significant change in the level of phosphorylation compared with untreated control cells. However, inhibition of protein phosphatase 2A activity completely blocked the delay in wound closure produced by β-AR agonists. In Calu-3 cells, where CFTR expression was inhibited by RNAi, salbutamol did not inhibit wound repair, suggesting that β-AR agonist stimulation and loss of CFTR function share a common pathway leading to inhibition of epithelial repair. Confocal images of the basal membrane of Calu-3 cells labeled with anti-β1-integrin (clone HUTS-4) antibody showed that treatment with epinephrine or carvedilol reduced the level of activated integrin in the membrane. These findings suggest that treatment with β-AR agonists delays airway epithelial repair by a G protein- and cAMP-independent mechanism involving protein phosphatase 2A and a reduction in β1-integrin activation in the basal membrane.
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Affiliation(s)
| | - Nathan A Zaidman
- Department of Integrative Biology and Physiology, University of Minnesota, St. Paul, Minnesota
| | - Peter J Maniak
- Department of Animal Science, University of Minnesota, St. Paul, Minnesota; and
| | - Scott M O'Grady
- Department of Animal Science, University of Minnesota, St. Paul, Minnesota; and Department of Integrative Biology and Physiology, University of Minnesota, St. Paul, Minnesota
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13
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Pu J, Cao L, McCaig CD. Physiological extracellular electrical signals guide and orient the polarity of gut epithelial cells. Tissue Barriers 2015; 3:e1037417. [PMID: 26451341 PMCID: PMC4574889 DOI: 10.1080/21688370.2015.1037417] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 03/24/2015] [Accepted: 03/27/2015] [Indexed: 01/09/2023] Open
Abstract
Apical-basal polarity in epithelial cells is a fundamental process in the morphogenesis of many tissues. But how epithelial cells become oriented with functionally specialized luminal and serosal facing membranes is not understood fully. Cell-cell and cell-substrate contacts induce the asymmetric distribution of Na+/K+-ATPase pumps on basal membrane and are essential for apical-basal polarity formation. Inhibition of the Na+/K+-ATPase pump abolished apical formation completely. But it is unclear how this pump regulated the apical polarity. We discovered that the transepithelial potential difference (TEP) which is dependent on the basal Na+/K+-ATPase distribution acts as an essential coordinating signal for apical membrane formation through Ror2/ERK1/2/LKB1 signaling. A similar concept applies to all other ion-transporting epithelial and endothelial tissues and this raises the possibility of regulating the TEP as a therapeutic intervention for disorders in which epithelial function is compromised by faulty electrical signaling.
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Affiliation(s)
- Jin Pu
- School of Medical Sciences; Institute of Medical Sciences; University of Aberdeen ; Aberdeen, UK
| | - Lin Cao
- School of Medical Sciences; Institute of Medical Sciences; University of Aberdeen ; Aberdeen, UK
| | - Colin D McCaig
- School of Medical Sciences; Institute of Medical Sciences; University of Aberdeen ; Aberdeen, UK
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14
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Guo X, Jiang X, Ren X, Sun H, Zhang D, Zhang Q, Zhang J, Huang Y. The Galvanotactic Migration of Keratinocytes is Enhanced by Hypoxic Preconditioning. Sci Rep 2015; 5:10289. [PMID: 25988491 PMCID: PMC4437307 DOI: 10.1038/srep10289] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 04/09/2015] [Indexed: 12/15/2022] Open
Abstract
The endogenous electric field (EF)-directed migration of keratinocytes (galvanotaxis) into wounds is an essential step in wound re-epithelialization. Hypoxia, which occurs immediately after injury, acts as an early stimulus to initiate the healing process; however, the mechanisms for this effect, remain elusive. We show here that the galvanotactic migration of keratinocytes was enhanced by hypoxia preconditioning as a result of the increased directionality rather than the increased motility of keratinocytes. This enhancement was both oxygen tension- and preconditioning time-dependent, with the maximum effects achieved using 2% O2 preconditioning for 6 hours. Hypoxic preconditioning (2% O2, 6 hours) decreased the threshold voltage of galvanotaxis to < 25 mV/mm, whereas this value was between 25 and 50 mV/mm in the normal culture control. In a scratch-wound monolayer assay in which the applied EF was in the default healing direction, hypoxic preconditioning accelerated healing by 1.38-fold compared with the control conditions. Scavenging of the induced ROS by N-acetylcysteine (NAC) abolished the enhanced galvanotaxis and the accelerated healing by hypoxic preconditioning. Our data demonstrate a novel and unsuspected role of hypoxia in supporting keratinocyte galvanotaxis. Enhancing the galvanotactic response of cells might therefore be a clinically attractive approach to induce improved wound healing.
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Affiliation(s)
- Xiaowei Guo
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Xupin Jiang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Xi Ren
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Huanbo Sun
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Dongxia Zhang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Qiong Zhang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Jiaping Zhang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
| | - Yuesheng Huang
- Institute of Burn Research, State Key Laboratory of Trauma, Burns and Combined Injury, Southwest Hospital, The Third Military Medical University, Chongqing, China
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15
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Wang Y, Rouabhia M, Lavertu D, Zhang Z. Pulsed electrical stimulation modulates fibroblasts' behaviour through the Smad signalling pathway. J Tissue Eng Regen Med 2015; 11:1110-1121. [PMID: 25712595 DOI: 10.1002/term.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 12/11/2014] [Accepted: 01/15/2015] [Indexed: 01/14/2023]
Abstract
The aim of this study was to investigate the healing characteristics and the underlying signalling pathway of human dermal fibroblasts under the influence of pulsed electrical stimulation (PES). Primary human dermal fibroblasts were seeded on polypyrrole-coated polyester fabrics and subjected to four different PES protocols. The parameters of the rectangular pulse included potential intensity (50 and 100 mV/mm) and stimulation time (pulse width 300 s within a period of 600 s, and pulse width 10 s within a period of 1200 s). Our study revealed that PES moderately improved the ability of the cells to migrate in association with a statistically significant (p < 0.05) increase of FGF2 secretion by the PES-exposed fibroblasts. These exposed fibroblasts were able to contract collagen gel matrix up to 48 h and this collagen gel contraction paralleled an increase in α-SMA mRNA expression and protein production from the PES-exposed fibroblasts. Interestingly, the effect of PES on the human fibroblasts involved the Smad signalling pathway, as we observed higher levels of phosphorylated Smad2 and Smad3 in the stimulated groups compared to the control groups. Overall, this study demonstrated that PES modulates fibroblast activities through the Smad signalling pathway, thus providing new mechanistic insights related to the use of PES to promote wound healing in humans. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Yongliang Wang
- Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire, Université Laval, Québec, QC, Canada.,Axe Médecine régénératrice, Centre de Recherche du CHU de Québec, Département de Chirurgie, Faculté de Médecine, Université Laval, QC, Canada
| | - Mahmoud Rouabhia
- Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire, Université Laval, Québec, QC, Canada
| | - Denis Lavertu
- Département de Chirurgie Plastique, Hôpital Saint-François d'Assise, Québec, Canada
| | - Ze Zhang
- Axe Médecine régénératrice, Centre de Recherche du CHU de Québec, Département de Chirurgie, Faculté de Médecine, Université Laval, QC, Canada
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16
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Tissue engineering of electrically responsive tissues using polyaniline based polymers: A review. Biomaterials 2014; 35:9068-86. [DOI: 10.1016/j.biomaterials.2014.07.020] [Citation(s) in RCA: 291] [Impact Index Per Article: 29.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 07/17/2014] [Indexed: 11/19/2022]
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17
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Martin-Granados C, McCaig CD. Harnessing the Electric Spark of Life to Cure Skin Wounds. Adv Wound Care (New Rochelle) 2014; 3:127-138. [PMID: 24761353 PMCID: PMC3928811 DOI: 10.1089/wound.2013.0451] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Accepted: 04/17/2013] [Indexed: 01/02/2023] Open
Abstract
Significance: Skin wounds cause great distress and are a huge economic burden, particularly with an increasingly aging population that heals poorly. There is an urgent need for better therapies that improve repair. Intracellular signaling pathways that regulate wound repair are activated by growth factors, hormones, and cytokines released at the wound. In addition, endogenous electric fields (EFs) are generated by epithelia in response to injury and are an important cue that coordinates cell behavior at wounds. Electrical stimulation (ES), therefore, holds the potential to be effective therapeutically in treating wounds. Recent Advances: ES of wounds is an old idea based on observations of the natural occurrence of EF at wound sites. However, it is now receiving increasing attention, because (1) the underpinning mechanisms are being clarified; (2) devices that measure skin wound currents are in place; and (3) medical devices that apply EF to poorly healing wounds are in clinical use with promising results. Critical Issues: Several signaling proteins transduce the EF influence to cells. However, a bigger picture of the EF-proteome is needed in order to understand this complex process and target it in a controlled manner. Future Directions: Dissecting the signaling pathways driving electrical wound healing will allow further identification of key molecular switches that control the cellular response to EFs. These findings herald the development of a new concept, the use of hydrogel electrodes impregnated with small molecules that target signaling pathways to explore the potential of dual electric-pharmacological therapies to repair wounds.
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Affiliation(s)
- Cristina Martin-Granados
- College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
| | - Colin D. McCaig
- College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Aberdeen, United Kingdom
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Cortese B, Palamà IE, D'Amone S, Gigli G. Influence of electrotaxis on cell behaviour. Integr Biol (Camb) 2014; 6:817-30. [DOI: 10.1039/c4ib00142g] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Understanding the mechanism of cell migration and interaction with the microenvironment is not only of critical significance to the function and biology of cells, but also has extreme relevance and impact on physiological processes and diseases such as morphogenesis, wound healing, neuron guidance, and cancer metastasis.
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Affiliation(s)
- Barbara Cortese
- NNL
- Institute of Nanoscience CNR
- 73100 Lecce, Italy
- Department of Physics
- University Sapienza
| | | | | | - Giuseppe Gigli
- NNL
- Institute of Nanoscience CNR
- 73100 Lecce, Italy
- Department of Mathematics and Physics
- University of Salento
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Stock C, Ludwig FT, Hanley PJ, Schwab A. Roles of ion transport in control of cell motility. Compr Physiol 2013; 3:59-119. [PMID: 23720281 DOI: 10.1002/cphy.c110056] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cell motility is an essential feature of life. It is essential for reproduction, propagation, embryonic development, and healing processes such as wound closure and a successful immune defense. If out of control, cell motility can become life-threatening as, for example, in metastasis or autoimmune diseases. Regardless of whether ciliary/flagellar or amoeboid movement, controlled motility always requires a concerted action of ion channels and transporters, cytoskeletal elements, and signaling cascades. Ion transport across the plasma membrane contributes to cell motility by affecting the membrane potential and voltage-sensitive ion channels, by inducing local volume changes with the help of aquaporins and by modulating cytosolic Ca(2+) and H(+) concentrations. Voltage-sensitive ion channels serve as voltage detectors in electric fields thus enabling galvanotaxis; local swelling facilitates the outgrowth of protrusions at the leading edge while local shrinkage accompanies the retraction of the cell rear; the cytosolic Ca(2+) concentration exerts its main effect on cytoskeletal dynamics via motor proteins such as myosin or dynein; and both, the intracellular and the extracellular H(+) concentration modulate cell migration and adhesion by tuning the activity of enzymes and signaling molecules in the cytosol as well as the activation state of adhesion molecules at the cell surface. In addition to the actual process of ion transport, both, channels and transporters contribute to cell migration by being part of focal adhesion complexes and/or physically interacting with components of the cytoskeleton. The present article provides an overview of how the numerous ion-transport mechanisms contribute to the various modes of cell motility.
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Affiliation(s)
- Christian Stock
- Institute of Physiology II, University of Münster, Münster, Germany.
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Jahanshahi A, Schonfeld L, Janssen MLF, Hescham S, Kocabicak E, Steinbusch HWM, van Overbeeke JJ, Temel Y. Electrical stimulation of the motor cortex enhances progenitor cell migration in the adult rat brain. Exp Brain Res 2013; 231:165-77. [DOI: 10.1007/s00221-013-3680-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 08/07/2013] [Indexed: 02/07/2023]
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Tsai HF, Huang CW, Chang HF, Chen JJW, Lee CH, Cheng JY. Evaluation of EGFR and RTK signaling in the electrotaxis of lung adenocarcinoma cells under direct-current electric field stimulation. PLoS One 2013; 8:e73418. [PMID: 23951353 PMCID: PMC3739739 DOI: 10.1371/journal.pone.0073418] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Accepted: 07/17/2013] [Indexed: 11/18/2022] Open
Abstract
Physiological electric field (EF) plays a pivotal role in tissue development and regeneration. In vitro, cells under direct-current electric field (dcEF) stimulation may demonstrate directional migration (electrotaxis) and long axis reorientation (electro-alignment). Although the biophysical models and biochemical signaling pathways behind cell electrotaxis have been investigated in numerous normal cells and cancer cells, the molecular signaling mechanisms in CL1 lung adenocarcinoma cells have not been identified. Two subclones of CL1 cells, the low invasive CL1-0 cells and the highly invasive CL 1-5 cells, were investigated in the present study. CL1-0 cells are non-electrotactic while the CL 1-5 cells are anodally electrotactic and have high expression level of epidermal growth factor receptor (EGFR), in this study, we investigated the generally accepted hypothesis of receptor tyrosine kinase (RTK) activation in the two cell lines under dcEF stimulation. Erbitux, a therapeutic drug containing an anti-EGFR monoclonal antibody, cetuximab, was used to investigate the EGFR signaling in the electrotaxis of CL 1-5 cells. To investigate RTK phosphorylation and intracellular signaling in the CL1 cells, large amount of cellular proteins were collected in an airtight dcEF stimulation device, which has advantages of large culture area, uniform EF distribution, easy operation, easy cell collection, no contamination, and no medium evaporation. Commercial antibody arrays and Western blotting were used to study the phosphorylation profiles of major proteins in CL1 cells under dcEF stimulation. We found that electrotaxis of CL 1-5 cells is serum independent and EGFR independent. Moreover, the phosphorylation of Akt and S6 ribosomal protein (rpS6) in dcEF-stimulated CL1 cells are different from that in EGF-stimulated cells. This result suggests that CL1 cells' response to dcEF stimulation is not through EGFR-triggered pathways. The new large-scale dcEF stimulation device developed in the present work will aid the sample preparation for protein-based experiments.
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Affiliation(s)
- Hsieh-Fu Tsai
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Biophotonics & Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Ching-Wen Huang
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
| | - Hui-Fang Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
| | - Jeremy J. W. Chen
- Institute of Biomedical Sciences, National Chung Hsing University, Taichung, Taiwan
| | - Chau-Hwang Lee
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Biophotonics & Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan
| | - Ji-Yen Cheng
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Biophotonics & Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan
- Department of Mechanical and Mechatronic Engineering, National Taiwan Ocean University, Keelung, Taiwan
- * E-mail:
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22
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Tsai CH, Lin BJ, Chao PHG. α2β1 integrin and RhoA mediates electric field-induced ligament fibroblast migration directionality. J Orthop Res 2013; 31:322-7. [PMID: 22912342 DOI: 10.1002/jor.22215] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Accepted: 07/31/2012] [Indexed: 02/04/2023]
Abstract
Guided cell migration is important in tissue development, repair, and engineering. We have previously demonstrated that applied electric fields (EFs) enhanced and directed ligament fibroblast migration and collagen production, depending on EF parameters. Electrical stimulation is widely used for the treatment of pain and to promote wound healing. In orthopaedic practices, applied EFs promote bone healing and ligament repair in vivo. In the current study, stimulation waveforms used in physical therapy for promoting tissue repair were adapted to examine their effects on ACL fibroblast migration. Using different waveform and field strengths, we discovered a decoupling of cell motility and directionality, which suggests disparate mechanisms. Integrin, a major extracellular matrix receptor, polarized in response to applied EFs and controlled cell directionality and signaling. Furthermore, we demonstrated that RhoA is a mediator between integrin aggregation and directed cell migration. Polarization is essential in directed cell migration and our study establishes an outside-in signaling mechanism for EF-induced cell directionality.
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Affiliation(s)
- Cheng-Hsien Tsai
- Institute of Biomedical Engineering, College of Engineering and College of Medicine, National Taiwan University, Taipei, Taiwan
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Liu Y, Cui H, Zhuang X, Zhang P, Cui Y, Wang X, Wei Y, Chen X. Nano-hydroxyapatite Surfaces Grafted with Electroactive Aniline Tetramers for Bone-Tissue Engineering. Macromol Biosci 2013; 13:356-65. [DOI: 10.1002/mabi.201200345] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 11/23/2012] [Indexed: 11/11/2022]
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Hart FX, Laird M, Riding A, Pullar CE. Keratinocyte galvanotaxis in combined DC and AC electric fields supports an electromechanical transduction sensing mechanism. Bioelectromagnetics 2012; 34:85-94. [DOI: 10.1002/bem.21748] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Accepted: 07/24/2012] [Indexed: 01/11/2023]
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25
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Zhang HL, Peng HB. Mechanism of acetylcholine receptor cluster formation induced by DC electric field. PLoS One 2011; 6:e26805. [PMID: 22046365 PMCID: PMC3201969 DOI: 10.1371/journal.pone.0026805] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/04/2011] [Indexed: 11/18/2022] Open
Abstract
Background The formation of acetylcholine receptor (AChR) cluster is a key event during the development of the neuromuscular junction. It is induced through the activation of muscle-specific kinase (MuSK) by the heparan-sulfate proteoglycan agrin released from the motor axon. On the other hand, DC electric field, a non-neuronal stimulus, is also highly effective in causing AChRs to cluster along the cathode-facing edge of muscle cells. Methodology/Principal Findings To understand its molecular mechanism, quantum dots (QDs) were used to follow the movement of AChRs as they became clustered under the influence of electric field. From analyses of trajectories of AChR movement in the membrane, it was concluded that diffuse receptors underwent Brownian motion until they were immobilized at sites of cluster formation. This supports the diffusion-mediated trapping model in explaining AChR clustering under the influence of this stimulus. Disrupting F-actin cytoskeleton assembly and interfering with rapsyn-AChR interaction suppressed this phenomenon, suggesting that these are integral components of the trapping mechanism induced by the electric field. Consistent with the idea that signaling pathways are activated by this stimulus, the localization of tyrosine-phosphorylated forms of AChR β-subunit and Src was observed at cathodal AChR clusters. Furthermore, disrupting MuSK activity through the expression of a kinase-dead form of this enzyme abolished electric field-induced AChR clustering. Conclusions These results suggest that DC electric field as a physical stimulus elicits molecular reactions in muscle cells in the form of cathodal MuSK activation in a ligand-free manner to trigger a signaling pathway that leads to cytoskeletal assembly and AChR clustering.
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Affiliation(s)
- Hailong Luke Zhang
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
| | - H. Benjamin Peng
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
- * E-mail:
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26
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Huang CW, Chen HY, Yen MH, Chen JJW, Young TH, Cheng JY. Gene expression of human lung cancer cell line CL1-5 in response to a direct current electric field. PLoS One 2011; 6:e25928. [PMID: 21998723 PMCID: PMC3187831 DOI: 10.1371/journal.pone.0025928] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2011] [Accepted: 09/13/2011] [Indexed: 12/21/2022] Open
Abstract
Background Electrotaxis is the movement of adherent living cells in response to a direct current (dc) electric field (EF) of physiological strength. Highly metastatic human lung cancer cells, CL1–5, exhibit directional migration and orientation under dcEFs. To understand the transcriptional response of CL1–5 cells to a dcEF, microarray analysis was performed in this study. Methodology/Principal Findings A large electric-field chip (LEFC) was designed, fabricated, and used in this study. CL1–5 cells were treated with the EF strength of 0mV/mm (the control group) and 300mV/mm (the EF-treated group) for two hours. Signaling pathways involving the genes that expressed differently between the two groups were revealed. It was shown that the EF-regulated genes highly correlated to adherens junction, telomerase RNA component gene regulation, and tight junction. Some up-regulated genes such as ACVR1B and CTTN, and some down-regulated genes such as PTEN, are known to be positively and negatively correlated to cell migration, respectively. The protein-protein interactions of adherens junction-associated EF-regulated genes suggested that platelet-derived growth factor (PDGF) receptors and ephrin receptors may participate in sensing extracellular electrical stimuli. We further observed a high percentage of significantly regulated genes which encode cell membrane proteins, suggesting that dcEF may directly influence the activity of cell membrane proteins in signal transduction. Conclusions/Significance In this study, some of the EF-regulated genes have been reported to be essential whereas others are novel for electrotaxis. Our result confirms that the regulation of gene expression is involved in the mechanism of electrotactic response.
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Affiliation(s)
- Ching-Wen Huang
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
| | - Huai-Yi Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Department of Engineering and System Science, National Tsing-Hua University, Hsinchu, Taiwan
- Nano Science and Technology Program, Taiwan International Graduate Program (TIGP), Academia Sinica, Taipei, Taiwan
| | - Meng-Hua Yen
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
| | - Jeremy J. W. Chen
- Institutes of Biomedical Sciences and Molecular Biology, National Chung-Hsing University, Taichung, Taiwan
| | - Tai-Horng Young
- Institute of Biomedical Engineering, National Taiwan University, Taipei, Taiwan
| | - Ji-Yen Cheng
- Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan
- Department of Mechanical and Mechantronic Engineering, National Taiwan Ocean University, Keelung, Taiwan
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
- * E-mail:
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Wang M, Zhai P, Chen X, Schreyer DJ, Sun X, Cui F. Bioengineered scaffolds for spinal cord repair. TISSUE ENGINEERING PART B-REVIEWS 2011; 17:177-94. [PMID: 21338266 DOI: 10.1089/ten.teb.2010.0648] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Spinal cord injury can lead to devastating and permanent loss of neurological function, affecting all levels below the site of trauma. Unfortunately, the injured adult mammalian spinal cord displays little regenerative capacity and little functional recovery in large part due to a tissue environment that is nonpermissive for regenerative axon growth. Artificial tissue repair scaffolds may provide a physical guide to allow regenerative axon growth that bridges the lesion cavity and restores functional neural connectivity. By integrating different strategies, including the use of various biomaterials and microstructures as well as incorporation of bioactive molecules and living cells, combined or synergistic effects for spinal cord repair through regenerative axon growth may be achieved. This article briefly reviews the development of bioengineered scaffolds for spinal cord repair, focusing on spinal cord injury and the subsequent cellular response, scaffold materials, fabrication techniques, and current therapeutic strategies. Key issues and challenges are also identified and discussed along with recommendations for future research.
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Affiliation(s)
- Mindan Wang
- Division of Biomedical Engineering, College of Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Shao S, Zhou S, Li L, Li J, Luo C, Wang J, Li X, Weng J. Osteoblast function on electrically conductive electrospun PLA/MWCNTs nanofibers. Biomaterials 2011; 32:2821-33. [PMID: 21292320 DOI: 10.1016/j.biomaterials.2011.01.051] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 01/04/2011] [Indexed: 11/30/2022]
Abstract
The electrospinning process was utilized successfully to fabricate the random oriented and aligned electrically conductive nanofibers of biodegradable poly-DL-lactide (PLA) in which multiwalled carbon nanotubes (MWCNTs) were embedded. The topographical features of the composite nanofibers were characterized by SEM. The dispersion and alignment of MWCNTs in nanofiber matrix were observed by TEM. The in vitro degradation was characterized in terms of the morphological change, the mass loss and the reduction of polymer molecular weight as well as the decrease of pH value of degradation media. In particular, these conductive nanofiber meshes offered a unique system to study the synergistic effect of topographic cues and electrical stimulation on osteoblasts outgrowth as a way of exploring their potential application in bone tissue engineering. The results of obsteoblasts assay unstimulated showed that the aligned nanofibers as topographic cues could enhance the extension and direct the outgrowth of obsteoblasts better than random fibers. In the presence of direct current (DC) of 100 μA, the obsteoblasts on all samples grew along the electrical current direction. The cellular elongation and proliferation were mainly dependent on the electrical stimulation whereas the topographical features played a minor role in them. Therefore, electrical stimulation with an appropriate DC value imparted on conductive substrate had great potential in application of bone tissue engineering.
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Affiliation(s)
- Shijun Shao
- School of Life Science and Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan, PR China
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Meng X, Arocena M, Penninger J, Gage FH, Zhao M, Song B. PI3K mediated electrotaxis of embryonic and adult neural progenitor cells in the presence of growth factors. Exp Neurol 2010; 227:210-7. [PMID: 21092738 DOI: 10.1016/j.expneurol.2010.11.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 09/28/2010] [Accepted: 11/04/2010] [Indexed: 01/17/2023]
Abstract
Correct guidance of the migration of neural progenitor cells (NPCs) is essential for the development and repair of the central nervous system (CNS). Electric field (EF)-guided migration, electrotaxis, has been observed in many cell types. We report here that, in applied EFs of physiological magnitude, embryonic and adult NPCs show marked electrotaxis, which is dependent on the PI3K/Akt pathway. The electrotaxis was also evidenced by ex vivo investigation that transplanted NPCs migrated directionally towards cathode in organotypic spinal cord slice model when treated with EFs. Genetic disruption or pharmacological inhibition of phosphoinositide 3-kinase (PI3K) impaired electrotaxis, whereas EF exposure increased Akt phosphorylation in a growth factor-dependent manner and increased phosphatidylinositol-3,4,5-trisphosphate (PIP3) levels. EF treatments also induced asymmetric redistribution of PIP3, growth factor receptors, and actin cytoskeleton. Electrotaxis in both embryonic and adult NPCs requires epidermal growth factor (EGF) and fibroblast growth factor (FGF). Our results demonstrate the importance of the PI3K/Akt pathway in directed migration of NPCs driven by EFs and growth factors and highlight the potential of EFs to enhance the guidance of various NPC populations in CNS repair therapies.
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Affiliation(s)
- Xiaoting Meng
- School of Dentistry, Cardiff Institute of Tissue Engineering & Repair, Cardiff University, Cardiff, CF14 4XY, UK
| | - Miguel Arocena
- School of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK
| | - Josef Penninger
- Institute of Molecular Biotechnology, Austrian Academy of Sciences, Dr. Bohr-Gasse, 1030 Vienna, Austria
| | - Fred H Gage
- Laboratory of Genetics, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA
| | - Min Zhao
- Institute for Regenerative Cures, UC Davis School of Medicine, 2921, Stockton Blvd, Sacramento, CA 95817, USA
| | - Bing Song
- School of Dentistry, Cardiff Institute of Tissue Engineering & Repair, Cardiff University, Cardiff, CF14 4XY, UK.,School of Medical Sciences, University of Aberdeen, Aberdeen, AB25 2ZD, UK
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Huang J, Hu X, Lu L, Ye Z, Zhang Q, Luo Z. Electrical regulation of Schwann cells using conductive polypyrrole/chitosan polymers. J Biomed Mater Res A 2010; 93:164-74. [PMID: 19536828 DOI: 10.1002/jbm.a.32511] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Electrical stimulation (ES) can dramatically enhance neurite outgrowth through conductive polymers and accelerate peripheral nerve regeneration in animal models of nerve injury. Therefore, conductive tissue engineering graft in combination with ES is a potential treatment for neural injuries. Conductive tissue engineering graft can be obtained by seeding Schwann cells on conductive scaffold. However, when ES is applied through the conductive scaffold, the impact of ES on Schwann cells has never been investigated. In this study, a biodegradable conductive composite made of conductive polypyrrole (PPy, 2.5%) and biodegradable chitosan (97.5%) was prepared in order to electrically stimulate Schwann cells. The tolerance of Schwann cells to ES was examined by a cell apoptosis assay. The growth of the cells was characterized using DAPI staining and a MTT assay. mRNA and protein levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in Schwann cells were assayed by RT-PCR and Western blotting, and the amount of NGF and BDNF secreted was determined by an ELISA assay. The results showed that the PPy/chitosan membranes supported cell adhesion, spreading, and proliferation with or without ES. Interestingly, ES applied through the PPy/chitosan composite dramatically enhanced the expression and secretion of NGF and BDNF when compared with control cells without ES. These findings highlight for the first time the possibility of enhancing nerve regeneration in conductive scaffolds through ES-increased neurotrophin secretion.
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Affiliation(s)
- Jinghui Huang
- Institute of Orthopaedics, Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
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31
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Jennings JA, Chen D, Feldman DS. Upregulation of chemokine (C-C motif) ligand 20 in adult epidermal keratinocytes in direct current electric fields. Arch Dermatol Res 2009; 302:211-20. [PMID: 19784662 DOI: 10.1007/s00403-009-0995-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Revised: 09/05/2009] [Accepted: 09/10/2009] [Indexed: 12/18/2022]
Abstract
Electric fields (EFs) of around 100 mV/mm are present in normal healing wounds and induce the directional migration of epithelial cells. Reepithelialization during wound healing thus may be controlled in part by this electrical signal. In this study, the early transcriptional response of human epidermal keratinocytes to EFs is examined using microarrays. Increased expression of various chemokines, interleukins, and other inflammatory response genes indicates that EFs stimulate keratinocyte activation and immune stimulatory activity. Gene expression activity further suggests that interleukin 1 is either released or activated in EFs. Expression of the chemokine CCL20 steadily increases at 100 mV/mm over time until around 8 h after exposure. This chemokine is also expressed at field strengths of 300 mV/mm-above the level of endogenous wound fields. The early effects of EFs on epithelial gene expression activity identified in these studies suggest the importance of naturally occurring EFs both in repair mechanisms and for the possibility of controlling these responses therapeutically.
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Affiliation(s)
- Jessica Amber Jennings
- Department of Biomedical Engineering, University of Alabama at Birmingham, 1075 13th St. South, Birmingham, AL 35294, USA.
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Zhao M. Electrical fields in wound healing-An overriding signal that directs cell migration. Semin Cell Dev Biol 2008; 20:674-82. [PMID: 19146969 DOI: 10.1016/j.semcdb.2008.12.009] [Citation(s) in RCA: 367] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 12/07/2008] [Accepted: 12/14/2008] [Indexed: 01/09/2023]
Abstract
Injury that disrupts an epithelial layer instantaneously generates endogenous electric fields (EFs), which were detected at human skin wounds over 150 years ago. Recent researches combining molecular, genetic and imaging techniques have provided significant insights into cellular and molecular responses to this "unconventional" signal. One unexpected finding is that the EFs play an overriding guidance role in directing cell migration in epithelial wound healing. In experimental models where other directional cues (e.g., contact inhibition release, population pressure etc.) are present, electric fields of physiological strength override them and direct cell migration. The electrotaxis or galvanotaxis is mediated by polarized activation of multiple signaling pathways that include PI3 kinases/Pten, membrane growth factor receptors and integrins. Genetic manipulation of PI3 kinase/Pten (Phosphoinositide 3-kinases/phosphatase and tensin homolog) and integrin beta4 demonstrated the importance of those molecules. The electric fields are therefore a fundamental signal that directs cell migration in wound healing. One of the most challenging question is: How do cells sense the very weak electric signals? Clinically, it is highly desirable to develop practical and reliable technologies for wound healing management exploiting the electric signaling.
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Affiliation(s)
- Min Zhao
- Department of Dermatology, University of California Davis, School of Medicine, Center for Neurosciences, 1515 Newton Ct., Davis, CA 95618-4859, USA.
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Nuccitelli R, Nuccitelli P, Ramlatchan S, Sanger R, Smith PJS. Imaging the electric field associated with mouse and human skin wounds. Wound Repair Regen 2008; 16:432-41. [PMID: 18471262 DOI: 10.1111/j.1524-475x.2008.00389.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
We have developed a noninvasive instrument called the bioelectric field imager (BFI) for mapping the electric field between the epidermis and the stratum corneum near wounds in both mouse and human skin. Rather than touching the skin, the BFI vibrates a small metal probe with a displacement of 180 mum in air above the skin to detect the surface potential of the epidermis through capacitative coupling. Here we describe our first application of the BFI measuring the electric field between the stratum corneum and epidermis at the margin of skin wounds in mice. We measured an electric field of 177+/-14 (61) mV/mm immediately upon wounding and the field lines pointed away from the wound in all directions around it. Because the wound current flows immediately upon wounding, this is the first signal indicating skin damage. This electric field is generated at the outer surface of the epidermis by the outward flow of the current of injury. An equal and opposite current must flow within the multilayered epidermis to generate an intraepidermal field with the negative pole at the wound site. Because the current flowing within the multilayered epidermis is spread over a larger area, the current density and subsequent E field generated in that region is expected to be smaller than that measured by the BFI beneath the stratum corneum. The field beneath the stratum corneum typically remained in the 150-200 mV/mm range for 3 days and then began to decline over the next few days, falling to zero once wound healing was complete. The mean wound field strength decreased by 64+/-7% following the application of the sodium channel blocker, amiloride, to the skin near the wound and increased by 82+/-21% following the application of the Cl- channel activator, prostaglandin E2.
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Affiliation(s)
- Richard Nuccitelli
- BioElectroMed Corporation, 849 Mitten Rd, Ste. 105, Burlingame, CA 94010, USA.
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Olayo R, Ríos C, Salgado-Ceballos H, Cruz GJ, Morales J, Olayo MG, Alcaraz-Zubeldia M, Alvarez AL, Mondragon R, Morales A, Diaz-Ruiz A. Tissue spinal cord response in rats after implants of polypyrrole and polyethylene glycol obtained by plasma. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2008; 19:817-26. [PMID: 17665119 DOI: 10.1007/s10856-007-3080-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2006] [Accepted: 04/05/2007] [Indexed: 05/16/2023]
Abstract
Most of the biomaterials used nowadays for the reconstruction of the spinal cord (SC) tissue after an injury, tested in animals, have obtained modest results. This work presents a study about the compatibility of two novel, non-biodegradable, semi-conductive materials, obtained by plasma polymerization: iodine-doped pyrrole (PPy/I) and pyrrole-polyethylene glycol (PPy/PEG). Both polymers, separately, were implanted in the SC tissue of rats after a transection. Prior to implantation, the elemental composition and the physico-chemical properties of polymers were studied by electron scanning microscopy, IR Spectroscopy and thermogravimetric analysis. We used adult female Long Evans rats, subjected to SC transection. Animals were randomized to be allocated in one of the treatment groups and were killed four weeks after the lesion for histology study. Results showed that both implants were integrated to the SC tissue, as inflammatory and gliotic responses, similar to those observed in the control group, and rejection of the implant, were not evident. Moreover, the immediate effect of PPy/I or PPy/PEG in the injured SC prevented secondary tissue destruction, as compared to non-implanted control animals. In conclusion, implants of semi-conductive polymers were well-tolerated and integrated favorably to SC tissue after transection.
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Affiliation(s)
- Roberto Olayo
- Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Mexico, Mexico
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Abstract
Beta2 adrenergic receptors were identified in keratinocytes more than 30 years ago, but their function in the epidermis continues to be elucidated. Abnormalities in their expression, signaling pathway, or in the generation of endogenous catecholamine agonists by keratinocytes have been implicated in the pathogenesis of cutaneous diseases such as atopic dermatitis, vitiligo, and psoriasis. New studies also indicate that the beta2AR also modulates keratinocyte migration, and thus can function to regulate wound reepithelialization. This review focuses on the function of these receptors in keratinocytes and their contribution to cutaneous physiology and disease.
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Affiliation(s)
- Raja K. Sivamani
- Medical Student, Department of Dermatology, University of California, Davis, CA 95616
| | - Susanne T. Lam
- Medical Student, Department of Dermatology, University of California, Davis, CA 95616
| | - R. Rivkah Isseroff
- Professor of Dermatology, Department of Dermatology, University of California, Davis, CA 95616 and Dermatology Service, Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655
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Rajnicek AM, Foubister LE, McCaig CD. Prioritising guidance cues: directional migration induced by substratum contours and electrical gradients is controlled by a rho/cdc42 switch. Dev Biol 2007; 312:448-60. [PMID: 17976566 DOI: 10.1016/j.ydbio.2007.09.051] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2007] [Revised: 09/25/2007] [Accepted: 09/25/2007] [Indexed: 01/30/2023]
Abstract
Coordinated cell migration is a fundamental feature of embryogenesis but the intracellular mechanism by which cells integrate co-existing extracellular cues to yield appropriate vectoral migration is unknown. Cells in the cornea are guided by a naturally occurring DC electric field (EF) (electrotaxis) as they navigate non-planar substrata but the relative potencies of electrotaxis and guidance by substratum shape (contact guidance) have never been determined. We tested the hypothesis that vectoral migration was controlled by selective activation of rac, cdc42 or rho in response to a 150 mV/mm EF or to a series of parallel substratum nanogrooves (NGs) 130 nm deep. EFs and NGs were presented singly or in combination. Electrotaxis of dissociated bovine corneal epithelial cells (CECs) on planar quartz required signalling by cdc42 and rho but not rac. Contact guidance by substratum NGs required rho but not cdc42 or rac activities. When an EF and NGs were superimposed in parallel, cathodal electrotaxis along NGs was enhanced compared to that on planar quartz but when they were superimposed orthogonally (vertical NGs with horizontal EF) cells were recruited from contact guidance to electrotaxis, suggesting that the EF was more potent. However, increasing the EF to 250 mV/mm was insufficient to recruit the majority to electrotaxis. Consistent for the cues in isolation, when an EF (150 mV/mm) and NGs were superimposed orthogonally, rac activity was not essential for either contact guidance or electrotaxis. However, attenuation of cdc42 signalling abolished electrotaxis and enhanced contact guidance relative to controls (no drug), whereas inhibiting rho signalling enhanced electrotaxis and rho stimulation enhanced contact guidance. Our data are consistent with the idea that migrating CECs use a cdc42/rho "switch" to sort vectoral cues, with cdc42 controlling electrotaxis and rho controlling contact guidance.
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Affiliation(s)
- Ann M Rajnicek
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, UK.
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37
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Large-scale biophysics: ion flows and regeneration. Trends Cell Biol 2007; 17:261-70. [PMID: 17498955 DOI: 10.1016/j.tcb.2007.04.007] [Citation(s) in RCA: 178] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2007] [Revised: 03/23/2007] [Accepted: 04/25/2007] [Indexed: 11/18/2022]
Abstract
Regeneration requires exquisite orchestration of growth and morphogenesis. A powerful but still largely mysterious system of biophysical signals functions during regeneration, embryonic development and neoplasm. Ion transporters generate pH and voltage gradients, as well as ion fluxes, regulating proliferation, differentiation and migration. Endogenous bioelectrical signals are implicated in the control of wound healing, limb development, left-right patterning and spinal cord regeneration. Recent advances in molecular biology and imaging technology have allowed unprecedented insight into the sources and downstream consequences of ion flows. In complement to the current focus on molecular genetics and stem cell biology, artificial modulation of bioelectrical signals in somatic tissues is a powerful modality that might result in profound advances in understanding and augmentation of regenerative capacity.
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Pullar CE, Zhao M, Song B, Pu J, Reid B, Ghoghawala S, McCaig C, Isseroff RR. Beta-adrenergic receptor agonists delay while antagonists accelerate epithelial wound healing: evidence of an endogenous adrenergic network within the corneal epithelium. J Cell Physiol 2007; 211:261-72. [PMID: 17226783 DOI: 10.1002/jcp.20934] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Wound healing is a complex and well-orchestrated biological process. Corneal epithelial cells (CECs) must respond quickly to trauma to rapidly restore barrier function and protect the eye from noxious agents. They express a high level of beta2-adrenergic receptors but their function is unknown. Here, we report the novel finding that they form part of a regulatory network in the corneal epithelium, capable of modulating corneal epithelial wound repair. Beta-adrenergic receptor agonists delay CEC migration via a protein phosphatase 2A-mediated mechanism and decrease both electric field-directed migration and corneal wound healing. Conversely, beta-adrenergic receptor antagonists accelerate CEC migration, enhance electric field-mediated directional migration, and promote corneal wound repair. We demonstrate that CECs express key enzymes required for epinephrine (beta-adrenergic receptor agonist) synthesis in the cytoplasm and can detect epinephrine in cell extracts. We propose that the mechanism for the pro-motogenic effect of the beta-adrenergic antagonist is blockade of the beta2-adrenergic receptor preventing autocrine catecholamine binding. Further investigation of this network will improve our understanding of one of the most frequently prescribed class of drugs.
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Affiliation(s)
- Christine E Pullar
- Department of Dermatology, University of California Davis, Davis, California, USA.
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Adams DS, Masi A, Levin M. H+ pump-dependent changes in membrane voltage are an early mechanism necessary and sufficient to induce Xenopus tail regeneration. Development 2007; 134:1323-35. [PMID: 17329365 DOI: 10.1242/dev.02812] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In many systems, ion flows and long-term endogenous voltage gradients regulate patterning events, but molecular details remain mysterious. To establish a mechanistic link between biophysical events and regeneration, we investigated the role of ion transport during Xenopus tail regeneration. We show that activity of the V-ATPase H(+) pump is required for regeneration but not wound healing or tail development. The V-ATPase is specifically upregulated in existing wound cells by 6 hours post-amputation. Pharmacological or molecular genetic loss of V-ATPase function and the consequent strong depolarization abrogates regeneration without inducing apoptosis. Uncut tails are normally mostly polarized, with discrete populations of depolarized cells throughout. After amputation, the normal regeneration bud is depolarized, but by 24 hours post-amputation becomes rapidly repolarized by the activity of the V-ATPase, and an island of depolarized cells appears just anterior to the regeneration bud. Tail buds in a non-regenerative ;refractory' state instead remain highly depolarized relative to uncut or regenerating tails. Depolarization caused by V-ATPase loss-of-function results in a drastic reduction of cell proliferation in the bud, a profound mispatterning of neural components, and a failure to regenerate. Crucially, induction of H(+) flux is sufficient to rescue axonal patterning and tail outgrowth in otherwise non-regenerative conditions. These data provide the first detailed mechanistic synthesis of bioelectrical, molecular and cell-biological events underlying the regeneration of a complex vertebrate structure that includes spinal cord, and suggest a model of the biophysical and molecular steps underlying tail regeneration. Control of H(+) flows represents a very important new modality that, together with traditional biochemical approaches, may eventually allow augmentation of regeneration for therapeutic applications.
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Affiliation(s)
- Dany S Adams
- Center for Regenerative and Developmental Biology, Forsyth Institute, and Developmental Biology Department, Harvard School of Dental Medicine, 140 The Fenway, Boston, MA 02115, USA
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Whitehead MA, Fan D, Akkaraju GR, Canham LT, Coffer JL. Accelerated calcification in electrically conductive polymer composites comprised of poly(ɛ-caprolactone), polyaniline, and bioactive mesoporous silicon. J Biomed Mater Res A 2007; 83:225-34. [PMID: 17647228 DOI: 10.1002/jbm.a.31547] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In this study the fabrication and characterization of an electrically conductive composite material comprised of poly(epsilon-caprolactone) (PCL), polyaniline (PANi), and bioactive mesoporous silicon (BioSilicon) is discussed. The influence of PANi and silicon on calcium phosphate induction was assessed via ex vitro calcification analyses (by acellular simulated body fluid (SBF) exposure) both with and without electrical bias. Acceleration of calcium phosphate formation is one possible desirable feature of "smart" synthetic scaffolds for selected orthopedic-relevant applications. In addition, electrical stability assays were performed in growth medium (DMEM) to determine the stability of such structures to bias in an authentic electrolyte during a typical cell experiment. The cytocompatibility of the composites was evaluated in vitro using human kidney fibroblasts (HEK 293) cell proliferation assays, along with more orthopedically relevant mesenchymal stem cells from mouse stroma. Importantly, these composites demonstrate accelerated calcification in SBF when electrical bias is applied cathodically to the scaffold. Furthermore, these scaffolds exhibit noncytotoxic behavior in the presence of fibroblasts over an 8-day culture period, and attachment of stromal cells to the semiconducting scaffold was directly imaged via scanning electron microscopy. Overall, these results suggest that materials of this type of composition have potential merit as a biomaterial.
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Affiliation(s)
- Melanie A Whitehead
- Department of Chemistry, Texas Christian University, Fort Worth, Texas 76129, USA
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Sato MJ, Ueda M, Takagi H, Watanabe TM, Yanagida T, Ueda M. Input-output relationship in galvanotactic response of Dictyostelium cells. Biosystems 2006; 88:261-72. [PMID: 17184899 DOI: 10.1016/j.biosystems.2006.06.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Accepted: 06/30/2006] [Indexed: 11/25/2022]
Abstract
Under a direct current electric field, Dictyostelium cells exhibit migration towards the cathode. To determine the input-output relationship of the cell's galvanotactic response, we developed an experimental instrument in which electric signals applied to the cells are highly reproducible and the motile response are analyzed quantitatively. With no electric field, the cells moved randomly in all directions. Upon applying an electric field, cell migration speeds became about 1.3 times faster than those in the absence of an electric field. Such kinetic effects of electric fields on the migration were observed for cells stimulated between 0.25 and 10 V/cm of the field strength. The directions of cell migrations were biased toward the cathode in a positive manner with field strength, showing galvanotactic response in a dose-dependent manner. Quantitative analysis of the relationship between field strengths and directional movements revealed that the biased movements of the cells depend on the square of electric field strength, which can be described by one simple phenomenological equation. The threshold strength for the galvanotaxis was between 0.25 and 1 V/cm. Galvanotactic efficiency reached to half-maximum at 2.6 V/cm, which corresponds to an approximate 8 mV voltage difference between the cathode and anode direction of 10 microm wide, round cells. Based on these results, possible mechanisms of galvanotaxis in Dictyostelium cells were discussed. This development of experimental system, together with its good microscopic accessibility for intracellular signaling molecules, makes Dictyostelium cells attractive as a model organism for elucidating stochastic processes in the signaling systems responsible for cell motility and its regulations.
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Affiliation(s)
- Masayuki J Sato
- Laboratories for Nanobiology, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
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Pullar CE, Baier BS, Kariya Y, Russell AJ, Horst BA, Marinkovich MP, Isseroff RR. beta4 integrin and epidermal growth factor coordinately regulate electric field-mediated directional migration via Rac1. Mol Biol Cell 2006; 17:4925-35. [PMID: 16914518 PMCID: PMC1635387 DOI: 10.1091/mbc.e06-05-0433] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Endogenous DC electric fields (EF) are present during embryogenesis and are generated in vivo upon wounding, providing guidance cues for directional cell migration (galvanotaxis) required in these processes. To understand the role of beta (beta)4 integrin in directional migration, the migratory paths of either primary human keratinocytes (NHK), beta4 integrin-null human keratinocytes (beta4-), or those in which beta4 integrin was reexpressed (beta4+), were tracked during exposure to EFs of physiological magnitude (100 mV/mm). Although the expression of beta4 integrin had no effect on the rate of cell movement, it was essential for directional (cathodal) migration in the absence of epidermal growth factor (EGF). The addition of EGF potentiated the directional response, suggesting that at least two distinct but synergistic signaling pathways coordinate galvanotaxis. Expression of either a ligand binding-defective beta4 (beta4+AD) or beta4 with a truncated cytoplasmic tail (beta4+CT) resulted in loss of directionality in the absence of EGF, whereas inhibition of Rac1 blinded the cells to the EF even in the presence of EGF. In summary, both the beta4 integrin ligand-binding and cytoplasmic domains together with EGF were required for the synergistic activation of a Rac-dependent signaling pathway that was essential for keratinocyte directional migration in response to a galvanotactic stimulus.
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Affiliation(s)
- Christine E. Pullar
- *Department of Dermatology, University of California, Davis, Davis, CA 95616
| | - Brian S. Baier
- *Department of Dermatology, University of California, Davis, Davis, CA 95616
| | - Yoshinobu Kariya
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Alan J. Russell
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - Basil A.J. Horst
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305
| | - M. Peter Marinkovich
- Program in Epithelial Biology, Stanford University School of Medicine, Stanford, CA 94305
- VA Palo Alto Health Care System, Department of Veterans Affairs, Stanford, CA 94304
| | - R. Rivkah Isseroff
- *Department of Dermatology, University of California, Davis, Davis, CA 95616
- Dermatology Service, Northern California Health Care System, Department of Veterans Affairs, Mather, CA 95655; and
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Pullar CE, Rizzo A, Isseroff RR. β-Adrenergic Receptor Antagonists Accelerate Skin Wound Healing. J Biol Chem 2006; 281:21225-21235. [PMID: 16714291 DOI: 10.1074/jbc.m601007200] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The skin is our primary defense against noxious environmental agents. Upon injury, keratinocytes migrate directionally into the wound bed to initiate re-epithelialization, essential for wound repair and restoration of barrier integrity. Keratinocytes express a high level of beta2-adrenergic receptors (beta2-ARs) that appear to play a role in cutaneous homeostasis as aberrations in either keratinocyte beta2-AR function or density are associated with various skin diseases. Here we report the novel finding that beta-AR antagonists promote wound re-epithelialization in a "chronic" human skin wound-healing model. beta-AR antagonists increase ERK phosphorylation, the rate of keratinocyte migration, electric field-directed migration, and ultimately accelerate human skin wound re-epithelialization. We demonstrate that keratinocytes express two key enzymes required for catecholamine (beta-AR agonist) synthesis, tyrosine hydroxylase and phenylethanolamine-N-methyl transferase, both localized within keratinocyte cytoplasmic vesicles. Finally, we confirm the synthesis of epinephrine by measuring the endogenously synthesized catecholamine in keratinocyte extracts. Previously, we have demonstrated that beta-AR agonists delay wound re-epithelialization. Here we report that the mechanism for the beta-AR antagonist-mediated augmentation of wound repair is due to beta2-AR blockade, preventing the binding of endogenously synthesized epinephrine. Our work describes an endogenous beta-AR mediator network in the skin that can temporally regulate skin wound repair. Further investigation of this network will improve our understanding of both the skin repair process and the multiple modes of action of one of the most frequently prescribed class of drugs, hopefully resulting in a new treatment for chronic wounds.
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Affiliation(s)
- Christine E Pullar
- Department of Dermatology, School of Medicine, University of California, Davis, California 95616.
| | - Amilcar Rizzo
- Department of Dermatology, School of Medicine, University of California, Davis, California 95616
| | - R Rivkah Isseroff
- Department of Dermatology, School of Medicine, University of California, Davis, California 95616; Dermatology Service, Department of Veterans Affairs, Northern California Health Care System, Mather, CA 95655
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44
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Godbout C, Frenette J. Periodic direct current does not promote wound closure in an in vitro dynamic model of cell migration. Phys Ther 2006; 86:50-9; discussion 59-65. [PMID: 16386062 DOI: 10.1093/ptj/86.1.50] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
BACKGROUND AND PURPOSE A prevailing paradigm is that electrical fields can promote cell migration and tissue healing. To further validate this paradigm, we tested the hypothesis that periodic direct current (DC) can enhance wound closure using an in vitro dynamic model of cell migration. METHODS AND RESULTS Layers of primary fibroblasts were wounded and treated with DC under various voltages. Repair area, cell velocity, and directionality as well as lamellipodium area were evaluated at different times. Direct current had no beneficial effect on cell migration. Moreover, prolonged stimulation under the highest voltage led to significant reduction in wound closure and cell velocity. The reduction of membrane protusions in stimulated cells may be associated with the deleterious effect of DC. DISCUSSION AND CONCLUSION Contrary to the authors' expectations, they found that periodic DC did not promote wound closure, a finding that emphasizes the need to clarify the complex effects of electrical fields on migrating cells.
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Affiliation(s)
- Charles Godbout
- Department of Rehabilitation, Laval University, Quebec City, Canada G1V 4G2
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McCaig CD, Rajnicek AM, Song B, Zhao M. Controlling cell behavior electrically: current views and future potential. Physiol Rev 2005; 85:943-78. [PMID: 15987799 DOI: 10.1152/physrev.00020.2004] [Citation(s) in RCA: 634] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Direct-current (DC) electric fields are present in all developing and regenerating animal tissues, yet their existence and potential impact on tissue repair and development are largely ignored. This is primarily due to ignorance of the phenomenon by most researchers, some technically poor early studies of the effects of applied fields on cells, and widespread misunderstanding of the fundamental concepts that underlie bioelectricity. This review aims to resolve these issues by describing: 1) the historical context of bioelectricity, 2) the fundamental principles of physics and physiology responsible for DC electric fields within cells and tissues, 3) the cellular mechanisms for the effects of small electric fields on cell behavior, and 4) the clinical potential for electric field treatment of damaged tissues such as epithelia and the nervous system.
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Affiliation(s)
- Colin D McCaig
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, Scotland.
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46
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Pullar CE, Isseroff RR. Cyclic AMP mediates keratinocyte directional migration in an electric field. J Cell Sci 2005; 118:2023-34. [PMID: 15840650 DOI: 10.1242/jcs.02330] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Re-epithelialization of wounded skin is necessary for wound closure and restoration of barrier function and requires directional keratinocyte migration towards the center of the wound. The electric field (EF) generated immediately upon wounding could be the earliest signal keratinocytes receive to initiate directional migration and healing. Keratinocytes express many beta2-adrenergic receptors (beta2-ARs), but their role in the epidermis is unknown. We have previously shown that beta-AR agonists decrease keratinocyte migration in a cyclic AMP (cAMP) independent mechanism involving the activation of protein phosphatase 2A (PP2A). Here, we ask whether beta2-ARs play a role in keratinocyte galvanotaxis. We report a bimodal response. When keratinocytes were exposed to higher concentrations of beta-AR agonist (0.1 microM), their tracked migratory speed was inhibited, in both the presence (directional migration) and the absence (random migration) of a 100 mV mm(-1) EF, as expected. At lower agonist concentrations (0.1 pM to 0.1 nM), there was no effect on migratory speed; however, all directionality was lost - essentially, cells were 'blinded' to the directional cue. Preincubating the cells with beta-antagonist restored directional migration, demonstrating that the 'blindness' was beta2-AR mediated. Incubation of keratinocytes with agents known to increase intracellular cAMP levels, such as sp-cAMP, pertussis toxin and forskolin, resulted in similar 'blinding' to the EF, whereas random migration was unaffected. The inactive cAMP analog rp-cAMP had no effect on keratinocyte migration, whether directional or random. However, rp-cAMP pretreatment before beta-agonist addition fully restored galvanotaxis, demonstrating the complete cAMP dependence of the attenuation of keratinocyte directional migration. This is the first report that cAMP is capable of mediating keratinocyte galvanotaxis. beta-AR agonists and antagonists could be valuable tools for modulating re-epithelialization, an essential step in the wound-healing process. Thus, beta-ARs regulate the two distinct components of keratinocyte directional migration differently: migration speed via a cAMP-independent mechanism and galvanotaxis by a cAMP-dependent one.
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Affiliation(s)
- Christine E Pullar
- Department of Dermatology, University of California, Davis, CA 95616, USA.
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47
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Shi G, Rouabhia M, Wang Z, Dao LH, Zhang Z. A novel electrically conductive and biodegradable composite made of polypyrrole nanoparticles and polylactide. Biomaterials 2004; 25:2477-88. [PMID: 14751732 DOI: 10.1016/j.biomaterials.2003.09.032] [Citation(s) in RCA: 176] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A novel electrically conductive biodegradable composite material made of polypyrrole (PPy) nanoparticles and poly(d,l-lactide) (PDLLA) was prepared by emulsion polymerization of pyrrole in a PDLLA solution, followed by precipitation. The composite was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The electrical stability of the composite containing 5 wt% PPy was investigated in a cell culture environment for 1000 h with 100 mV DC applied voltage. Fibroblasts were cultured on the composite membranes and were stimulated with various DC currents. The PPy particles formed aggregations and constituted microdomains and networks embedded in the PDLLA. With the 1-17% increase in the PPy content, the conductivity of the composite increased by six orders of magnitude. The surface resistivity of the PPy/PDLLA membrane with 3% PPy was as low as 1x10(3) Omega/square. The electrical stability was significantly better in the PPy/PDLLA composite than in the PPy-coated polyester fabrics. For the composite with 5% PPy, the test membrane retained 80% and 42% of the initial conductivity in 100 and 400 h, respectively, following the addition of the MEM solution, compared to 5% and 0.1% for the PPy-coated polyester fabrics. Under 100 mV, a composite membrane 3.0x2.5x0.03cm3 in size and containing 5% PPy sustained a biologically meaningful electrical conductivity in a typical cell culture environment for 1000 h. The growth of fibroblasts was up regulated under the stimulation of medium range intensity of DC current.
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Affiliation(s)
- Guixin Shi
- Département de chirurgie, Université Laval, Centre de recherche, Hôpital Saint-François d'Assise, CHUQ, Québec (QC), Canada
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48
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Mycielska ME, Djamgoz MBA. Cellular mechanisms of direct-current electric field effects: galvanotaxis and metastatic disease. J Cell Sci 2004; 117:1631-9. [PMID: 15075225 DOI: 10.1242/jcs.01125] [Citation(s) in RCA: 228] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Endogenous direct-current electric fields (dcEFs) occur in vivo in the form of epithelial transcellular potentials or neuronal field potentials, and a variety of cells respond to dcEFs in vitro by directional movement. This is termed galvanotaxis. The passive influx of Ca2+ on the anodal side should increase the local intracellular Ca2+ concentration, whereas passive efflux and/or intracellular redistribution decrease the local intracellular Ca2+ concentration on the cathodal side. These changes could give rise to `push-pull' effects, causing net movement of cells towards the cathode. However, such effects would be complicated in cells that possess voltage-gated Ca2+ channels and/or intracellular Ca2+ stores. Moreover, voltage-gated Na+ channels, protein kinases, growth factors, surface charge and electrophoresis of proteins have been found to be involved in galvanotaxis. Galvanotactic mechanisms might operate in both the short term (seconds to minutes) and the long term (minutes to hours), and recent work has shown that they might be involved in metastatic disease. The galvanotactic responses of strongly metastatic prostate and breast cancer cells are much more prominent, and the cells move in the opposite direction compared with corresponding weakly metastatic cells. This could have important implications for the metastatic process and has clinical implications. Galvanotaxis could thus play a significant role in both cellular physiology and pathophysiology.
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Affiliation(s)
- Maria E Mycielska
- Department of Biological Sciences, Neuroscience Solutions to Cancer Research Group, Imperial College London, Sir Alexander Fleming Building, South Kensington Campus, London, SW7 2AZ, UK
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Abstract
This review focuses on the experimental evidence supporting a role for endogenous electric fields in wound healing in vertebrates. Most wounds involve the disruption of epithelial layers composing the epidermis or surrounding organs in the body. These epithelia generate a steady voltage across themselves that will drive an injury current out of the wounded region, generating a lateral electric field that has been measured in four different cases to be 40-200 mV/mm. Many epithelial cells, including human keratinocytes, have the ability to detect electric fields of this magnitude and respond with directed migration. Their response typically requires Ca2+ influx, the presence of specific growth factors and intracellular kinase activity. Protein kinase C is required by neural crest cells and cAMP-dependent protein kinase is used in keratinocytes while mitogen-activated protein kinase is required by corneal epithelial cells. Several recent experiments support a role for electric fields in the stimulation of wound healing in the developing frog neurula, adult newt skin and adult mammalian cornea. Some experiments indicate that when the electric field is removed the wound healing rate is 25% slower. In addition, nearly every clinical trial using electric fields to stimulate healing in mammalian wounds reports a significant increase in the rate of healing from 13 to 50%. However, these trials have utilized many different field strengths and polarities, so much work is needed to optimize this approach for the treatment of mammalian wounds.
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