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Gatenby RA, Luddy KA, Teer JK, Berglund A, Freischel AR, Carr RM, Lam AE, Pienta KJ, Amend SR, Austin RH, Hammarlund EU, Cleveland JL, Tsai KY, Brown JS. Lung adenocarcinomas without driver genes converge to common adaptive strategies through diverse genetic, epigenetic, and niche construction evolutionary pathways. Med Oncol 2024; 41:135. [PMID: 38704802 PMCID: PMC11070398 DOI: 10.1007/s12032-024-02344-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 02/21/2024] [Indexed: 05/07/2024]
Abstract
Somatic evolution selects cancer cell phenotypes that maximize survival and proliferation in dynamic environments. Although cancer cells are molecularly heterogeneous, we hypothesized convergent adaptive strategies to common host selection forces can be inferred from patterns of epigenetic and genetic evolutionary selection in similar tumors. We systematically investigated gene mutations and expression changes in lung adenocarcinomas with no common driver genes (n = 313). Although 13,461 genes were mutated in at least one sample, only 376 non-synonymous mutations evidenced positive evolutionary selection with conservation of 224 genes, while 1736 and 2430 genes exhibited ≥ two-fold increased and ≥ 50% decreased expression, respectively. Mutations under positive selection are more frequent in genes with significantly altered expression suggesting they often "hardwire" pre-existing epigenetically driven adaptations. Conserved genes averaged 16-fold higher expression in normal lung tissue compared to those with selected mutations demonstrating pathways necessary for both normal cell function and optimal cancer cell fitness. The convergent LUAD phenotype exhibits loss of differentiated functions and cell-cell interactions governing tissue organization. Conservation with increased expression is found in genes associated with cell cycle, DNA repair, p53 pathway, epigenetic modifiers, and glucose metabolism. No canonical driver gene pathways exhibit strong positive selection, but extensive down-regulation of membrane ion channels suggests decreased transmembrane potential may generate persistent proliferative signals. NCD LUADs perform niche construction generating a stiff, immunosuppressive microenvironment through selection of specific collagens and proteases. NCD LUADs evolve to a convergent phenotype through a network of interconnected genetic, epigenetic, and ecological pathways.
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Affiliation(s)
- Robert A Gatenby
- Department of Cancer Biology and Evolution, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA.
| | - Kimberly A Luddy
- Department of Cancer Biology and Evolution, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA
| | - Jamie K Teer
- Department of Cancer Biology and Evolution, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA
- Department of Bioinformatics, Moffitt Cancer Center, Tampa, USA
| | - Anders Berglund
- Department of Cancer Biology and Evolution, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA
- Department of Bioinformatics, Moffitt Cancer Center, Tampa, USA
| | | | - Ryan M Carr
- Department of Oncology, Mayo Clinic, Rochester, USA
| | | | - Kenneth J Pienta
- Cancer Ecology Program, Johns Hopkins University, Baltimore, USA
| | - Sarah R Amend
- Cancer Ecology Program, Johns Hopkins University, Baltimore, USA
| | | | - Emma U Hammarlund
- Division of Translational Cancer Research, Lund University, Lund, Sweden
| | - John L Cleveland
- Department of Cancer Biology and Evolution, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA
| | - Kenneth Y Tsai
- Departments of Pathology and Tumor Biology, Moffitt Cancer Center, Tampa, USA
| | - Joel S Brown
- Department of Cancer Biology and Evolution, Moffitt Cancer Center, 12902 Magnolia Drive, Tampa, FL, 33612, USA
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Physical Forces in Glioblastoma Migration: A Systematic Review. Int J Mol Sci 2022; 23:ijms23074055. [PMID: 35409420 PMCID: PMC9000211 DOI: 10.3390/ijms23074055] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/31/2022] [Accepted: 04/04/2022] [Indexed: 02/01/2023] Open
Abstract
The invasive capabilities of glioblastoma (GBM) define the cancer’s aggressiveness, treatment resistance, and overall mortality. The tumor microenvironment influences the molecular behavior of cells, both epigenetically and genetically. Current forces being studied include properties of the extracellular matrix (ECM), such as stiffness and “sensing” capabilities. There is currently limited data on the physical forces in GBM—both relating to how they influence their environment and how their environment influences them. This review outlines the advances that have been made in the field. It is our hope that further investigation of the physical forces involved in GBM will highlight new therapeutic options and increase patient survival. A search of the PubMed database was conducted through to 23 March 2022 with the following search terms: (glioblastoma) AND (physical forces OR pressure OR shear forces OR compression OR tension OR torsion) AND (migration OR invasion). Our review yielded 11 external/applied/mechanical forces and 2 tumor microenvironment (TME) forces that affect the ability of GBM to locally migrate and invade. Both external forces and forces within the tumor microenvironment have been implicated in GBM migration, invasion, and treatment resistance. We endorse further research in this area to target the physical forces affecting the migration and invasion of GBM.
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Numerical study on the effect of capacitively coupled electrical stimulation on biological cells considering model uncertainties. Sci Rep 2022; 12:4744. [PMID: 35304501 PMCID: PMC8933463 DOI: 10.1038/s41598-022-08279-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 03/03/2022] [Indexed: 11/08/2022] Open
Abstract
Electrical stimulation of biological samples such as tissues and cell cultures attracts growing attention due to its capability of enhancing cell activity, proliferation, and differentiation. Eventually, a profound knowledge of the underlying mechanisms paves the way for innovative therapeutic devices. Capacitive coupling is one option of delivering electric fields to biological samples that has advantages regarding biocompatibility. However, its biological mechanism of interaction is not well understood. Experimental findings could be related to voltage-gated channels, which are triggered by changes of the transmembrane potential. Numerical simulations by the finite element method provide a possibility to estimate the transmembrane potential. Since a full resolution of the cell membrane within a macroscopic model would lead to prohibitively expensive models, we suggest the adaptation of an approximate finite element method. Starting from a basic 2.5D model, the chosen method is validated and applied to realistic experimental situations. To understand the influence of the dielectric properties on the modelling outcome, uncertainty quantification techniques are employed. A frequency-dependent influence of the uncertain dielectric properties of the cell membrane on the modelling outcome is revealed. This may have practical implications for future experimental studies. Our methodology can be easily adapted for computational studies relying on experimental data.
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Simeonov S, Schäffer TE. Ultrafast Imaging of Cardiomyocyte Contractions by Combining Scanning Ion Conductance Microscopy with a Microelectrode Array. Anal Chem 2019; 91:9648-9655. [PMID: 31247725 DOI: 10.1021/acs.analchem.9b01092] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Beating cardiomyocytes undergo fast morphodynamics during the contraction-relaxation cycle. However, imaging these morphodynamics with a high spatial and temporal resolution is difficult, owing to a lack of suitable techniques. Here, we combine scanning ion conductance microscopy (SICM) with a microelectrode array (MEA) to image the three-dimensional (3D) topography of cardiomyocytes during a contraction-relaxation cycle with 1 μm spatial and 1 ms time resolution. We record the vertical motion of cardiomyocytes at many locations across a cell by SICM and synchronize these data using the simultaneously recorded action potential by the MEA as a time reference. This allows us to reconstruct the time-resolved 3D morphology of cardiomyocytes during a full contraction-relaxation cycle with a raw data rate of 200 μs/frame and to generate spatially resolved images of contractile parameters (maximum displacement, time delay, asymmetry factor). We use the MEA-SICM setup to visualize the effect of blebbistatin, a myosin II inhibitor, on the morphodynamics of contractions. Further, we find an upper limit of 0.02% for cell volume changes during an action potential. The results show that MEA-SICM provides an ultrafast imaging platform for investigating the functional interplay of cardiomyocyte electrophysiology and mechanics.
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Affiliation(s)
- Stefan Simeonov
- Institute of Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
| | - Tilman E Schäffer
- Institute of Applied Physics , University of Tübingen , Auf der Morgenstelle 10 , 72076 Tübingen , Germany
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Lim JT, Yoon YS, Lee WY, Jeong JT, Kim GS, Kim TG, Lee SK. Microfluidic channel-coupled 3D quartz nanohole arrays for high capture and release efficiency of BT20 cancer cells. NANOSCALE 2017; 9:17224-17232. [PMID: 29068023 DOI: 10.1039/c7nr04961g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nanostructured materials, such as silicon nanowires, quartz nanostructures, and polymer-modified nanostructures, are a promising new class of materials for the capture and enumeration of very rare tumor cells, including circulating tumor cells (CTCs), to examine their biological characteristics in whole blood of cancer patients. These cells can then be used for transplantation, anti-tumor cell therapy, and cell-secreted protein studies. It is believed that 3-dimensional (3D) nanostructured substrates efficiently enhance cell capture yields due to the increased local contacts between the 3D nanostructures and extracellular extensions of the tumor cells. Recent studies have been performed with enhanced cell capture yields thanks to various nanostructured platforms; however, there remains an urgent need both to capture and release viable rare tumor cells for further molecular (i.e., protein) analysis and to develop patient-specific drugs. Here, we first demonstrate that our 3D quartz nanohole array (QNHA) tumor cell capture and release system allows us not only to selectively capture rare tumor cells, but also to release the cells with high capture and release rates. This system was developed using streptavidin (STR)-functionalized QNHA (STR-QNHA) with a microfluidic channel. Our system has ideal cell-separation yields of as high as 85-91% and high release rates of >90% for the BT20 cell line. We suggest that the use of a microfluidic channel technique coupled with a STR-QNHA cell capture and release chip (STR-QNHA cell chip) would be a powerful and simple process to evaluate the capture, enumeration, and release of CTCs from patient whole blood for studying further cell therapy and tumor-cell-secreted molecules.
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Affiliation(s)
- Jung-Taek Lim
- Department of Physics, Chung-Ang University, Seoul 06974, Republic of Korea.
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Casula E, Asuni GP, Sogos V, Fadda S, Delogu F, Cincotti A. Osmotic behaviour of human mesenchymal stem cells: Implications for cryopreservation. PLoS One 2017; 12:e0184180. [PMID: 28886069 PMCID: PMC5590898 DOI: 10.1371/journal.pone.0184180] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2017] [Accepted: 08/19/2017] [Indexed: 12/19/2022] Open
Abstract
Aimed at providing a contribution to the optimization of cryopreservation processes, the present work focuses on the osmotic behavior of human mesenchymal stem cells (hMSCs). Once isolated from the umbilical cord blood (UCB) of three different donors, hMSCs were characterized in terms of size distribution and their osmotic properties suitably evaluated through the exposure to hypertonic and isotonic aqueous solutions at three different temperatures. More specifically, inactive cell volume and cell permeability to water and di-methyl sulfoxide (DMSO) were measured, being cell size determined using impedance measurements under both equilibrium and dynamic conditions. Experimental findings indicate that positive cell volume excursions are limited by the apparent increase of inactive volume, which occurs during both the shrink-swell process following DMSO addition and the subsequent restoration of isotonic conditions in the presence of hypertonic solutions of impermeant or permeant solutes. Based on this evidence, hMSCs must be regarded as imperfect osmometers, and their osmotic behavior described within a scenario no longer compatible with the simple two-parameter model usually utilized in the literature. In this respect, the activation of mechano-sensitive ion-channels seemingly represents a reasonable hypothesis for rationalizing the observed osmotic behavior of hMSCs from UCB.
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Affiliation(s)
- Elisa Casula
- Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Cagliari, Italy
| | - Gino P. Asuni
- Centro Interdipartimentale di Ingegneria e Scienze Ambientali, Università degli Studi di Cagliari, Cagliari, Italy
| | - Valeria Sogos
- Dipartimento di Scienze Biomediche, Università degli Studi di Cagliari, Cittadella Universitaria, Monserrato, Italy
| | - Sarah Fadda
- Centre for Process Systems Engineering, Department of Chemical Engineering, Imperial College London, London, United Kingdom
| | - Francesco Delogu
- Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Cagliari, Italy
| | - Alberto Cincotti
- Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Università degli Studi di Cagliari, Cagliari, Italy
- Centro Interdipartimentale di Ingegneria e Scienze Ambientali, Università degli Studi di Cagliari, Cagliari, Italy
- * E-mail:
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Leguèbe M, Silve A, Mir L, Poignard C. Conducting and permeable states of cell membrane submitted to high voltage pulses: Mathematical and numerical studies validated by the experiments. J Theor Biol 2014; 360:83-94. [DOI: 10.1016/j.jtbi.2014.06.027] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 06/11/2014] [Accepted: 06/22/2014] [Indexed: 10/25/2022]
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How medium osmolarity influences dielectrophoretically assisted on-chip electrofusion. Bioelectrochemistry 2014; 100:27-35. [PMID: 25012938 DOI: 10.1016/j.bioelechem.2014.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 05/23/2014] [Accepted: 05/27/2014] [Indexed: 12/11/2022]
Abstract
Cells submitted to an electric field gradient experience dielectrophoresis. Such a force is useful for pairing cells prior to electrofusion. The latter event is induced by the application of electric field pulses leading to membrane fusion while cells are in physical contact. Nevertheless, the efficiency of dielectrophoretic pairing and electrofusion of cells are highly dependent on medium properties (osmolarity and conductivity). In this paper, we examine the effect of medium osmolarity on volume, viability and electrical properties of cells. Then we characterize in real time the impact of electropermeabilization of cells on their dielectrophoretic response. To do so, a microfluidic device, inducing particular field topologies is used. These real time observations are correlated to numerical analysis of the Clausius-Mossotti factor. Taking into account the identified changes, an electrofusion protocol adequate to the optimal medium (100 mOsm, 0.03 S/m) is defined. Up to 75% simultaneous binuclear rapid electrofusions were achieved and monitored with average membrane fusion duration lower than 12s.
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Romeo S, Wu YH, Levine ZA, Gundersen MA, Vernier PT. Water influx and cell swelling after nanosecond electropermeabilization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1715-22. [DOI: 10.1016/j.bbamem.2013.03.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 02/20/2013] [Accepted: 03/01/2013] [Indexed: 10/27/2022]
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10
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Francis F, García MR, Middleton RH. A single compartment model of pacemaking in dissasociated substantia nigra neurons: stability and energy analysis. J Comput Neurosci 2013; 35:295-316. [PMID: 23686304 DOI: 10.1007/s10827-013-0453-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 04/01/2013] [Accepted: 04/03/2013] [Indexed: 01/08/2023]
Abstract
Spontaneous oscillations in the mid-brain dopaminergic neurons are an important feature of motor control. The degeneration of these neurons is involved in movement disorders, particularly Parkinson's Disease. Modelling of this activity is an important part of developing an understanding of the pathogenic process. We develop a mathematical paradigm to describe this activity with a single compartment approach and a CellML version is made publicly available. The model explicitly describes the dynamics of the transmembrane potential with changes in the levels of important cations and is consistent with two major observations in the literature regarding its behaviour in the presence of channel blockers. Stability of the model behaviour is determined from the properties of its Monodromy matrix. We also discuss from the perspective of energy, a pharmacological intervention suggested in the treatment of Parkinson's Disease.
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Affiliation(s)
- Febe Francis
- Hamilton Institute, NUI Maynooth, Co. Kildare, Ireland
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Fernández JM, Di Giusto G, Kalstein M, Melamud L, Rivarola V, Ford P, Capurro C. Cell volume regulation in cultured human retinal Müller cells is associated with changes in transmembrane potential. PLoS One 2013; 8:e57268. [PMID: 23451196 PMCID: PMC3581454 DOI: 10.1371/journal.pone.0057268] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/18/2013] [Indexed: 01/18/2023] Open
Abstract
Müller cells are mainly involved in controlling extracellular homeostasis in the retina, where intense neural activity alters ion concentrations and osmotic gradients, thus favoring cell swelling. This increase in cell volume is followed by a regulatory volume decrease response (RVD), which is known to be partially mediated by the activation of K+ and anion channels. However, the precise mechanisms underlying osmotic swelling and subsequent cell volume regulation in Müller cells have been evaluated by only a few studies. Although the activation of ion channels during the RVD response may alter transmembrane potential (Vm), no studies have actually addressed this issue in Müller cells. The aim of the present work is to evaluate RVD using a retinal Müller cell line (MIO-M1) under different extracellular ionic conditions, and to study a possible association between RVD and changes in Vm. Cell volume and Vm changes were evaluated using fluorescent probe techniques and a mathematical model. Results show that cell swelling and subsequent RVD were accompanied by Vm depolarization followed by repolarization. This response depended on the composition of extracellular media. Cells exposed to a hypoosmotic solution with reduced ionic strength underwent maximum RVD and had a larger repolarization. Both of these responses were reduced by K+ or Cl− channel blockers. In contrast, cells facing a hypoosmotic solution with the same ionic strength as the isoosmotic solution showed a lower RVD and a smaller repolarization and were not affected by blockers. Together, experimental and simulated data led us to propose that the efficiency of the RVD process in Müller glia depends not only on the activation of ion channels, but is also strongly modulated by concurrent changes in the membrane potential. The relationship between ionic fluxes, changes in ion permeabilities and ion concentrations –all leading to changes in Vm– define the success of RVD.
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Affiliation(s)
- Juan M. Fernández
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Gisela Di Giusto
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Maia Kalstein
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Luciana Melamud
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- Consultorio de Neuroinmunología, Centro Universitario de Neurología Dr. J.M. Ramos Mejía, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Rivarola
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Paula Ford
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
| | - Claudia Capurro
- Laboratorio de Biomembranas, Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad de Buenos Aires, Ciudad Autónoma de Buenos Aires, Buenos Aires, Argentina
- * E-mail:
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Mu X, Zheng W, Sun J, Zhang W, Jiang X. Microfluidics for manipulating cells. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2013; 9:9-21. [PMID: 22933509 DOI: 10.1002/smll.201200996] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/05/2012] [Indexed: 05/02/2023]
Abstract
Microfluidics, a toolbox comprising methods for precise manipulation of fluids at small length scales (micrometers to millimeters), has become useful for manipulating cells. Its uses range from dynamic management of cellular interactions to high-throughput screening of cells, and to precise analysis of chemical contents in single cells. Microfluidics demonstrates a completely new perspective and an excellent practical way to manipulate cells for solving various needs in biology and medicine. This review introduces and comments on recent achievements and challenges of using microfluidics to manipulate and analyze cells. It is believed that microfluidics will assume an even greater role in the mechanistic understanding of cell biology and, eventually, in clinical applications.
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Affiliation(s)
- Xuan Mu
- Key Laboratory for Biological Effects of Nanomaterials and Nanosafety, Chinese Academy of Sciences, National Center for NanoScience and Technology, No. 11, Beiyitiao, ZhongGuanCun, Beijing 100190, PR China
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Kim DJ, Seol JK, Lee G, Kim GS, Lee SK. Cell adhesion and migration on nanopatterned substrates and their effects on cell-capture yield. NANOTECHNOLOGY 2012; 23:395102. [PMID: 22971755 DOI: 10.1088/0957-4484/23/39/395102] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
With scanning electron microscopy analysis, we investigated the role of nanoscale topography on cellular activities; e.g. cell adhesion and spreading by culturing A549 cells (human lung carcinoma cell line cells) for 1-48 h on three sets of nanostructures; quartz nanopillars (QNPs), silicon nanopillars and silicon nanowire (SiNW) arrays, along with planar glass substrates. We found that cells on QNP arrays developed a longer shape than those on SiNW arrays. In addition, we studied how cell morphologies influence the cell-capture yield on the three sets of nanostructures. This research showed that the filopodial formations were directing the cell-capture yield on nanostructured substrates. This finding implies the possibility of using nanoscale topography features to control the filopodial formation including extension and migration from the cells. Using streptavidin-functionalized SiNW substrate, we further demonstrated a substantially higher yield (~91.8 ± 5.9%) than the planar glass wafers (~24.1 ± 7.5%) in the range of 200-3000 cells.
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Affiliation(s)
- Dong-Joo Kim
- Basic Research Laboratory (BRL), Department of Semiconductor Science and Technology, Chonbuk National University, Jeonju, 561-756, Korea
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Cha CY, Noma A. Steady-state solutions of cell volume in a cardiac myocyte model elaborated for membrane excitation, ion homeostasis and Ca2+ dynamics. J Theor Biol 2012; 307:70-81. [PMID: 22584248 DOI: 10.1016/j.jtbi.2012.04.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 02/27/2012] [Accepted: 04/17/2012] [Indexed: 01/15/2023]
Abstract
The cell volume continuously changes in response to varying physiological conditions, and mechanisms underlying volume regulation have been investigated in both experimental and theoretical studies. Here, general formulations concerning cell volume change are presented in the context of developing a comprehensive cell model which takes Ca(2+) dynamics into account. Explicit formulas for charge conservation and steady-state volumes of the cytosol and endoplasmic reticulum (ER) are derived in terms of membrane potential, amount of ions, Ca(2+)-bound buffer molecules, and initial cellular conditions. The formulations were applied to a ventricular myocyte model which has plasma-membrane Ca(2+) currents with dynamic gating mechanisms, Ca(2+)-buffering reactions with diffusive and non-diffusive buffer proteins, and Ca(2+) uptake into or release from the sarcoplasmic reticulum (SR) accompanied by compensatory cationic or anionic currents through the SR membrane. Time-dependent volume changes in cardiac myocytes induced by varying extracellular osmolarity or by action potential generation were successfully simulated by the novel formulations. Through application of bifurcation analysis, the existence and uniqueness of steady-state solutions of the cell volume were validated, and contributions of individual ion channels and transporters to the steady-state volume were systematically analyzed. The new formulas are consistent with previous fundamental theory derived from simple models of minimum compositions. The new formulations may be useful for examination of the relationship between cell function and volume change in other cell types.
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Affiliation(s)
- Chae Young Cha
- Biosimulation Project, Faculty of Bioinformatics, Ritsumeikan University, Japan.
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Patil AV, Premaraban T, Berthoumieu O, Watts A, Davis JJ. Engineered Bacteriorhodopsin: A Molecular Scale Potential Switch. Chemistry 2012; 18:5632-6. [DOI: 10.1002/chem.201103597] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 02/24/2012] [Indexed: 11/10/2022]
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Abstract
There are three kinds of membrane potentials: the surface potentials, resulting from the accumulation of charges at the membrane surfaces; the transmembrane potential, determined by imbalance of charge in the aqueous solutions; and the dipole potential, a membrane-internal potential from the dipolar components of the phospholipids and interface water. The absolute value of the dipole potential has been very difficult to measure, although its value has been estimated to be in the range of 200-1,000 mV from ion translocation rates (determined by the planar lipid bilayer method), the surface potential of lipid monolayers (determined by the lipid monolayer method), molecular-dynamics calculations, and electron scattering using cryoelectron microscopy (cryo-EM). Spectroscopy methods have also been used to monitor the dipole potential changes on the basis of the observed fluorescence changes of voltage-sensitive probes. The dipole potential accounts for the much larger permeability of a bare phospholipid membrane to anions than cations and affects the conformation and function of membrane proteins.
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Affiliation(s)
- Liguo Wang
- Department of Biological Structure, University of Washington, Seattle, Washington 98195, USA.
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Lewis R, Feetham CH, Barrett-Jolley R. Cell volume regulation in chondrocytes. Cell Physiol Biochem 2011; 28:1111-22. [PMID: 22179000 DOI: 10.1159/000335847] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2011] [Indexed: 11/19/2022] Open
Abstract
Chondrocytes are the cells within cartilage which produce and maintain the extracellular matrix. Volume regulation in these cells is vital to their function and occurs in several different physiological and pathological contexts. Firstly, chondrocytes exist within an environment of changing osmolarity and compressive loads. Secondly, in osteoarthritic joint failure, cartilage water content changes and there is a notable increase in chondrocyte apoptosis. Thirdly, endochondral ossification requires chondrocyte swelling in association with hypertrophy. Regulatory volume decrease (RVD) and regulatory volume increase (RVI) have both been observed in articular chondrocytes and this review focuses on the mechanisms identified to account for these. There has been evidence so far to suggest TRPV4 is central to RVD; however other elements of the pathway have not yet been identified. Unlike RVD, RVI appears less robust in articular chondrocytes and there have been fewer mechanistic studies; the primary focus being on the Na(+)-K(+)-2Cl(-) co-transporter. The clinical significance of chondrocyte volume regulation remains unproven. Importantly however, transcript abundances of several ion channels implicated in volume control are changed in chondrocytes from osteoarthritic cartilage. A critical question is whether disturbances of volume regulation mechanisms lead to, result from or are simply coincidental to cartilage damage.
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Affiliation(s)
- Rebecca Lewis
- Department of Musculoskeletal Biology, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK
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