1
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Norris S, Hu JK, Shubin NH. Whole Tissue Imaging of Cellular Boundaries at Sub-Micron Resolutions for Automatic Cell Segmentation: Applications in Epithelial Bending of Ectodermal Appendages. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.26.600880. [PMID: 38979339 PMCID: PMC11230380 DOI: 10.1101/2024.06.26.600880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
For decades, biologists have relied on confocal microscopy to understand cellular morphology and the fine details of tissue structure. However, traditional confocal microscopy of tissues have limited penetration depths of light ∼ 100 µm due to tissue opaqueness. Researchers have, thus, developed tissue clearing protocols to be used with confocal microscopy, however, current clearing protocols are not compatible with labels of cell boundaries, especially at high enough resolution to precisely segment individual cells. In this work, we devise a method to retain markers of cell boundaries, and refractive index-match the tissues with water to enable tissue imaging at high magnification using long working distance water dipping objectives. The sub-micron resolution of these images allows us to automatically segment each individual cell using a trained neural network segmentation model. These segmented images can then be utilized to quantify cell properties and morphology of the entire three-dimensional tissue. As an example application, we first test our methodology on mandibles of mutant mice that express fluorescent proteins in their membranes. We then examine a non-model animal, the catshark, and explore the cellular properties of their dental lamina and dermal denticles, which are invaginating and evaginating ectodermal structures, respectively. We, thus, demonstrate that the technique presented here provides a powerful tool to quantify, in high-throughput, the 3D structures of cells and tissues during organ morphogenesis.
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2
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Mattiassi S, Conner AA, Feng F, Goh ELK, Yim EKF. The Combined Effects of Topography and Stiffness on Neuronal Differentiation and Maturation Using a Hydrogel Platform. Cells 2023; 12:cells12060934. [PMID: 36980275 PMCID: PMC10047827 DOI: 10.3390/cells12060934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Revised: 03/12/2023] [Accepted: 03/13/2023] [Indexed: 03/30/2023] Open
Abstract
Biophysical parameters such as substrate topography and stiffness have been shown independently to elicit profound effects on neuronal differentiation and maturation from neural progenitor cells (NPCs) yet have not been investigated in combination. Here, the effects of various micrograting and stiffness combinations on neuronal differentiation and maturation were investigated using a polyacrylamide and N-acryloyl-6-aminocaproic acid copolymer (PAA-ACA) hydrogel with tunable stiffness. Whole laminin was conjugated onto the PAA-ACA surface indirectly or directly to facilitate long-term mouse and human NPC-derived neuron attachment. Three micrograting dimensions (2-10 µm) were patterned onto gels with varying stiffness (6.1-110.5 kPa) to evaluate the effects of topography, stiffness, and their interaction. The results demonstrate that the extracellular matrix (ECM)-modified PAA-ACA gels support mouse and human neuronal cell attachment throughout the differentiation and maturation stages (14 and 28 days, respectively). The interaction between topography and stiffness is shown to significantly increase the proportion of β-tubulin III (TUJ1) positive neurons and microtubule associated protein-2 (MAP2) positive neurite branching and length. Thus, the effects of topography and stiffness cannot be imparted. These results provide a novel platform for neural mechanobiology studies and emphasize the utility of optimizing numerous biophysical cues for improved neuronal yield in vitro.
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Affiliation(s)
- Sabrina Mattiassi
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Abigail A Conner
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Fan Feng
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
| | - Eyleen L K Goh
- Neuroscience and Mental Health Faculty, Lee Kong China School of Medicine, Nanyang Technological University, Singapore 308232, Singapore
| | - Evelyn K F Yim
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Waterloo Institute for Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
- Center for Biotechnology and Bioengineering, University of Waterloo, 200 University Avenue West, Waterloo, ON N2L 3G1, Canada
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3
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Pieroth S, Heras‐Bautista CO, Hamad S, Brockmeier K, Hescheler J, Pfannkuche K, Schmidt AM. Poly(acrylamide) Spheroids with Tunable Elasticity for Scalable Cell Culture Applications. MACROMOL CHEM PHYS 2022. [DOI: 10.1002/macp.202200246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Stephanie Pieroth
- Chemistry Department Institute for Physical Chemistry University of Cologne 50939 Cologne Germany
| | - Carlos O. Heras‐Bautista
- Center for Physiology and Pathophysiology Institute for Neurophysiology University of Cologne Medical Faculty and University Hospital 50931 Cologne Germany
| | - Sarkawt Hamad
- Center for Physiology and Pathophysiology Institute for Neurophysiology University of Cologne Medical Faculty and University Hospital 50931 Cologne Germany
- Biology Department Faculty of Science Soran University Soran Kurdistan Region JGXP+9QW Iraq
- Marga‐and‐Walter‐Boll Laboratory for Cardiac Tissue Engineering University of Cologne 50931 Cologne Germany
| | - Konrad Brockmeier
- Department of Pediatric Cardiology University Hospital of Cologne 50937 Cologne Germany
| | - Jürgen Hescheler
- Center for Physiology and Pathophysiology Institute for Neurophysiology University of Cologne Medical Faculty and University Hospital 50931 Cologne Germany
| | - Kurt Pfannkuche
- Center for Physiology and Pathophysiology Institute for Neurophysiology University of Cologne Medical Faculty and University Hospital 50931 Cologne Germany
- Department of Pediatric Cardiology University Hospital of Cologne 50937 Cologne Germany
- Marga‐and‐Walter‐Boll Laboratory for Cardiac Tissue Engineering University of Cologne 50931 Cologne Germany
- Center for Molecular Medicine Cologne (CMMC) University of Cologne 50931 Cologne Germany
| | - Annette M. Schmidt
- Chemistry Department Institute for Physical Chemistry University of Cologne 50939 Cologne Germany
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4
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Labouesse C, Tan BX, Agley CC, Hofer M, Winkel AK, Stirparo GG, Stuart HT, Verstreken CM, Mulas C, Mansfield W, Bertone P, Franze K, Silva JCR, Chalut KJ. StemBond hydrogels control the mechanical microenvironment for pluripotent stem cells. Nat Commun 2021; 12:6132. [PMID: 34675200 PMCID: PMC8531294 DOI: 10.1038/s41467-021-26236-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Accepted: 09/22/2021] [Indexed: 12/12/2022] Open
Abstract
Studies of mechanical signalling are typically performed by comparing cells cultured on soft and stiff hydrogel-based substrates. However, it is challenging to independently and robustly control both substrate stiffness and extracellular matrix tethering to substrates, making matrix tethering a potentially confounding variable in mechanical signalling investigations. Moreover, unstable matrix tethering can lead to poor cell attachment and weak engagement of cell adhesions. To address this, we developed StemBond hydrogels, a hydrogel in which matrix tethering is robust and can be varied independently of stiffness. We validate StemBond hydrogels by showing that they provide an optimal system for culturing mouse and human pluripotent stem cells. We further show how soft StemBond hydrogels modulate stem cell function, partly through stiffness-sensitive ERK signalling. Our findings underline how substrate mechanics impact mechanosensitive signalling pathways regulating self-renewal and differentiation, indicating that optimising the complete mechanical microenvironment will offer greater control over stem cell fate specification.
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Affiliation(s)
- Céline Labouesse
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - Bao Xiu Tan
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Chibeza C Agley
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - Moritz Hofer
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - Alexander K Winkel
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
| | - Giuliano G Stirparo
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - Hannah T Stuart
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - Christophe M Verstreken
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Carla Mulas
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - William Mansfield
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
| | - Paul Bertone
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK
- Department of Medicine, Alpert Medical School, Brown University, Providence, IR, USA
| | - Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK
- Institute of Medical Physics, Friedrich-Alexander University Erlangen-Nuremberg, 91052, Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, 91054, Erlangen, Germany
| | - José C R Silva
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK.
- Center for Cell Lineage and Atlas, Guangzhou Laboratory, Guangzhou International Bio Island, 510005, Guangzhou, Guangdong Province, China.
| | - Kevin J Chalut
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Puddicombe Way, Cambridge, CB2 0AW, UK.
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, CB3 0HE, UK.
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3DY, UK.
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5
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Norris SCP, Soto J, Kasko AM, Li S. Photodegradable Polyacrylamide Gels for Dynamic Control of Cell Functions. ACS APPLIED MATERIALS & INTERFACES 2021; 13:5929-5944. [PMID: 33502154 DOI: 10.1021/acsami.0c19627] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Cross-linked polyacrylamide hydrogels are commonly used in biotechnology and cell culture applications due to advantageous properties, such as the precise control of material stiffness and the attachment of cell adhesive ligands. However, the chemical and physical properties of polyacrylamide gels cannot be altered once fabricated. Here, we develop a photodegradable polyacrylamide gel system that allows for a dynamic control of polyacrylamide gel stiffness with exposure to light. Photodegradable polyacrylamide hydrogel networks are produced by copolymerizing acrylamide and a photocleavable ortho-nitrobenzyl (o-NB) bis-acrylate cross-linker. When the hydrogels are exposed to light, the o-NB cross-links cleave and the stiffness of the photodegradable polyacrylamide gels decreases. Further examination of the effect of dynamic stiffness changes on cell behavior reveals that in situ softening of the culture substrate leads to changes in cell behavior that are not observed when cells are cultured on presoftened gels, indicating that both dynamic and static mechanical environments influence cell fate. Notably, we observe significant changes in nuclear localization of YAP and cytoskeletal organization after in situ softening; these changes further depend on the type and concentration of cell adhesive proteins attached to the gel surface. By incorporating the simplicity and well-established protocols of standard polyacrylamide gel fabrication with the dynamic control of photodegradable systems, we can enhance the capability of polyacrylamide gels, thereby enabling cell biologists and engineers to study more complex cellular behaviors that were previously inaccessible using regular polyacrylamide gels.
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Affiliation(s)
- Sam C P Norris
- Department of Bioengineering, University of California Los Angeles, 410 Westwood Plaza, 5121 Engineering V, Los Angeles, California 90095, United States
| | - Jennifer Soto
- Department of Bioengineering, University of California Los Angeles, 410 Westwood Plaza, 5121 Engineering V, Los Angeles, California 90095, United States
| | - Andrea M Kasko
- Department of Bioengineering, University of California Los Angeles, 410 Westwood Plaza, 5121 Engineering V, Los Angeles, California 90095, United States
| | - Song Li
- Department of Bioengineering, University of California Los Angeles, 410 Westwood Plaza, 5121 Engineering V, Los Angeles, California 90095, United States
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6
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Lee JY, Chaudhuri O. Regulation of Breast Cancer Progression by Extracellular Matrix Mechanics: Insights from 3D Culture Models. ACS Biomater Sci Eng 2017; 4:302-313. [DOI: 10.1021/acsbiomaterials.7b00071] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Joanna Y. Lee
- Department of Mechanical
Engineering, Stanford University, 452 Escondido Mall, Building 520,
Room 226, Stanford, California 94305-4038, United States
| | - Ovijit Chaudhuri
- Department of Mechanical
Engineering, Stanford University, 452 Escondido Mall, Building 520,
Room 226, Stanford, California 94305-4038, United States
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7
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Price AJ, Huang EY, Sebastiano V, Dunn AR. A semi-interpenetrating network of polyacrylamide and recombinant basement membrane allows pluripotent cell culture in a soft, ligand-rich microenvironment. Biomaterials 2016; 121:179-192. [PMID: 28088685 DOI: 10.1016/j.biomaterials.2016.12.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Revised: 12/03/2016] [Accepted: 12/07/2016] [Indexed: 01/10/2023]
Abstract
The physical properties of the extracellular matrix play an essential role in guiding stem cell differentiation and tissue morphogenesis both in vivo and in vitro. Existing work to investigate the role of matrix mechanics in directing stem cell proliferation, self-renewal, and differentiation has been limited by the poor attachment and survival of human pluripotent cells cultured on soft matrices (Young's modulus E ≲ 1000 Pa). To address this limitation we developed a protocol for generating semi-interpenetrating networks of polyacrylamide and recombinant basement membrane. Using these materials, we found that human embryonic stem cells (hESCs) remained proliferative and pluripotent even when grown in small colonies and on surfaces ranging in stiffness from 150 to 12000 Pa, spanning the range of tissue stiffnesses likely to be encountered in the embryo. Considerable recent attention has focused on the role of the transcriptional coactivator and Hippo effector YAP in regulating differentiation and cell proliferation both in the early embryo and in vitro. We found that while YAP localized to the nucleus on substrates of E ≳ 1000 Pa, its localization was heterogeneous on substrates of moduli ≲ 450 Pa, with predominantly nuclear localization at the colony periphery and mixed cytoplasmic and nuclear localization for cells in the colony interior, a pattern reminiscent of YAP subcellular localization in the inner cell mass (ICM) of the early embryo. In addition, hESC colony dynamics were highly responsive to substrate stiffness, with cells assembling into monolayers, multilayer structures, and transient, hollow rosettes in response to decreasing substrate stiffnesses in the range of 12000 to 150 Pa. We suggest that soft, ligand-rich substrates such as are described here provide a promising means of recapitulating aspects of early mammalian development that are otherwise inaccessible, and more broadly may be useful in the derivation of complex tissues from pluripotent cells in an in vitro setting.
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Affiliation(s)
- Andrew J Price
- Biophysics Program, Stanford University, Stanford, CA 94305, USA
| | - Eva Y Huang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Vittorio Sebastiano
- Institute for Stem Cell Biology and Regenerative Medicine, Department of Obstetrics and Gynecology, Stanford School of Medicine, Stanford, CA 94305, USA
| | - Alexander R Dunn
- Biophysics Program, Stanford University, Stanford, CA 94305, USA; Department of Chemical Engineering, Stanford University, Stanford, CA 94305, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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8
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Lee JP, Kassianidou E, MacDonald JI, Francis MB, Kumar S. N-terminal specific conjugation of extracellular matrix proteins to 2-pyridinecarboxaldehyde functionalized polyacrylamide hydrogels. Biomaterials 2016; 102:268-76. [PMID: 27348850 PMCID: PMC4939314 DOI: 10.1016/j.biomaterials.2016.06.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 01/30/2023]
Abstract
Polyacrylamide hydrogels have been used extensively to study cell responses to the mechanical and biochemical properties of extracellular matrix substrates. A key step in fabricating these substrates is the conjugation of cell adhesion proteins to the polyacrylamide surfaces, which typically involves nonspecifically anchoring these proteins via side-chain functional groups. This can result in a loss of presentation control and altered bioactivity. Here, we describe a new functionalization strategy in which we anchor full-length extracellular matrix proteins to polyacrylamide substrates using 2-pyridinecarboxaldehyde, which can be co-polymerized into polyacrylamide gels and used to immobilize proteins by their N-termini. This one-step reaction proceeds under mild aqueous conditions and does not require additional reagents. We demonstrate that these substrates can readily conjugate to various extracellular matrix proteins, as well as promote cell adhesion and spreading. Notably, this chemistry supports the assembly and cellular remodeling of large collagen fibers, which is not observed using conventional side-chain amine-conjugation chemistry.
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Affiliation(s)
- Jessica P Lee
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; Department of Bioengineering, University of California, Berkeley, CA 94720, USA
| | - Elena Kassianidou
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, Berkeley, CA 94720, USA
| | - James I MacDonald
- Department of Chemistry, University of California, Berkeley, CA 94720, USA
| | - Matthew B Francis
- Department of Chemistry, University of California, Berkeley, CA 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Sanjay Kumar
- Department of Bioengineering, University of California, Berkeley, CA 94720, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, Berkeley, CA 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley CA 94720, USA.
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9
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Hind LE, Lurier EB, Dembo M, Spiller KL, Hammer DA. Effect of M1-M2 Polarization on the Motility and Traction Stresses of Primary Human Macrophages. Cell Mol Bioeng 2016; 9:455-465. [PMID: 28458726 PMCID: PMC5404741 DOI: 10.1007/s12195-016-0435-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/01/2016] [Indexed: 01/12/2023] Open
Abstract
Macrophages become polarized by cues in their environment and this polarization causes a functional change in their behavior. Two main subsets of polarized macrophages have been described. M1, or "classically activated" macrophages, are pro-inflammatory and M2, or "alternatively activated" macrophages, are anti-inflammatory. In this study, we investigated the motility and force generation of primary human macrophages polarized down the M1 and M2 pathways using chemokinesis assays and traction force microscopy on polyacrylamide gels. We found that M1 macrophages are significantly less motile and M2 macrophages are significantly more motile than unactivated M0 macrophages. We also showed that M1 macrophages generate significantly less force than M0 or M2 macrophages. We further found that M0 and M2, but not M1, macrophage force generation is dependent on ROCK signaling, as identified using the chemical inhibitor Y27632. Finally, using the chemical inhibitor blebbistatin, we found that myosin contraction is required for force generation by M0, M1, and M2 macrophages. This study represents the first investigation of the changes in the mechanical motility mechanisms used by macrophages after polarization.
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Affiliation(s)
- Laurel E. Hind
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA
| | - Emily B. Lurier
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA
| | - Micah Dembo
- Department of Biomedical Engineering, Boston University, Boston, MA
| | - Kara L. Spiller
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA
| | - Daniel A. Hammer
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA
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10
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van Oers RFM, Rens EG, LaValley DJ, Reinhart-King CA, Merks RMH. Mechanical cell-matrix feedback explains pairwise and collective endothelial cell behavior in vitro. PLoS Comput Biol 2014; 10:e1003774. [PMID: 25121971 PMCID: PMC4133044 DOI: 10.1371/journal.pcbi.1003774] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 06/20/2014] [Indexed: 12/14/2022] Open
Abstract
In vitro cultures of endothelial cells are a widely used model system of the collective behavior of endothelial cells during vasculogenesis and angiogenesis. When seeded in an extracellular matrix, endothelial cells can form blood vessel-like structures, including vascular networks and sprouts. Endothelial morphogenesis depends on a large number of chemical and mechanical factors, including the compliancy of the extracellular matrix, the available growth factors, the adhesion of cells to the extracellular matrix, cell-cell signaling, etc. Although various computational models have been proposed to explain the role of each of these biochemical and biomechanical effects, the understanding of the mechanisms underlying in vitro angiogenesis is still incomplete. Most explanations focus on predicting the whole vascular network or sprout from the underlying cell behavior, and do not check if the same model also correctly captures the intermediate scale: the pairwise cell-cell interactions or single cell responses to ECM mechanics. Here we show, using a hybrid cellular Potts and finite element computational model, that a single set of biologically plausible rules describing (a) the contractile forces that endothelial cells exert on the ECM, (b) the resulting strains in the extracellular matrix, and (c) the cellular response to the strains, suffices for reproducing the behavior of individual endothelial cells and the interactions of endothelial cell pairs in compliant matrices. With the same set of rules, the model also reproduces network formation from scattered cells, and sprouting from endothelial spheroids. Combining the present mechanical model with aspects of previously proposed mechanical and chemical models may lead to a more complete understanding of in vitro angiogenesis.
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Affiliation(s)
- René F. M. van Oers
- Life Sciences group, Centrum Wiskunde & Informatica, Amsterdam, The Netherlands
- Netherlands Consortium for System Biology - Netherlands Institute for Systems Biology, Amsterdam, The Netherlands
| | - Elisabeth G. Rens
- Life Sciences group, Centrum Wiskunde & Informatica, Amsterdam, The Netherlands
- Netherlands Consortium for System Biology - Netherlands Institute for Systems Biology, Amsterdam, The Netherlands
| | - Danielle J. LaValley
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America
| | - Cynthia A. Reinhart-King
- Department of Biomedical Engineering, Cornell University, Ithaca, New York, United States of America
| | - Roeland M. H. Merks
- Life Sciences group, Centrum Wiskunde & Informatica, Amsterdam, The Netherlands
- Netherlands Consortium for System Biology - Netherlands Institute for Systems Biology, Amsterdam, The Netherlands
- Mathematical Institute, Leiden University, Leiden, The Netherlands
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11
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Heras-Bautista CO, Katsen-Globa A, Schloerer NE, Dieluweit S, Abd El Aziz OM, Peinkofer G, Attia WA, Khalil M, Brockmeier K, Hescheler J, Pfannkuche K. The influence of physiological matrix conditions on permanent culture of induced pluripotent stem cell-derived cardiomyocytes. Biomaterials 2014; 35:7374-85. [PMID: 24889032 DOI: 10.1016/j.biomaterials.2014.05.027] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
Cardiomyocytes (CMs) from induced pluripotent stem (iPS) cells mark an important achievement in the development of in vitro pharmacological, toxicological and developmental assays and in the establishment of protocols for cardiac cell replacement therapy. Using CMs generated from murine embryonic stem cells and iPS cells we found increased cell-matrix interaction and more matured embryoid body (EB) structures in iPS cell-derived EBs. However, neither suspension-culture in form of purified cardiac clusters nor adherence-culture on traditional cell culture plastic allowed for extended culture of CMs. CMs grown for five weeks on polystyrene exhibit signs of massive mechanical stress as indicated by α-smooth muscle actin expression and loss of sarcomere integrity. Hydrogels from polyacrylamide allow adapting of the matrix stiffness to that of cardiac tissue. We were able to eliminate the bottleneck of low cell adhesion using 2,5-Dioxopyrrolidin-1-yl-6-acrylamidohexanoate as a crosslinker to immobilize matrix proteins on the gels surface. Finally we present an easy method to generate polyacrylamide gels with a physiological Young's modulus of 55 kPa and defined surface ligand, facilitating the culture of murine and human iPS-CMs, removing excess mechanical stresses and reducing the risk of tissue culture artifacts exerted by stiff substrates.
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Affiliation(s)
- Carlos O Heras-Bautista
- Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Alisa Katsen-Globa
- Fraunhofer Institute for Biomedical Engineering IBMT, St. Ingbert, Germany
| | | | - Sabine Dieluweit
- Institute of Complex Systems, ICS-7: Biomechanics, Forschungszentrum Jülich GmbH, Jülich, Germany
| | - Osama M Abd El Aziz
- Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany; Department of Pediatrics, Cairo University, Cairo, Egypt; Department of Paediatric Cardiology, University Clinics of Cologne, Cologne, Germany
| | - Gabriel Peinkofer
- Department of Internal Medicine III, University Clinics of Cologne, Cologne, Germany
| | - Wael A Attia
- Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany; Department of Pediatrics, Cairo University, Cairo, Egypt; Department of Paediatric Cardiology, University Clinics of Cologne, Cologne, Germany
| | - Markus Khalil
- Department of Paediatric Cardiology, University Clinics of Cologne, Cologne, Germany; Division of Pediatric Cardiology, University Children's Hospital, Giessen, Germany
| | - Konrad Brockmeier
- Department of Paediatric Cardiology, University Clinics of Cologne, Cologne, Germany
| | - Jürgen Hescheler
- Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany
| | - Kurt Pfannkuche
- Center for Physiology and Pathophysiology, Institute for Neurophysiology, University of Cologne, Cologne, Germany; Department of Paediatric Cardiology, University Clinics of Cologne, Cologne, Germany.
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12
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Eschweiler N, Keul H, Millaruelo M, Weberskirch R, Moeller M. Synthesis of α,ω-isocyanate telechelic polymethacrylate soft segments with activated ester side functionalities and their use for polyurethane synthesis. POLYM INT 2013. [DOI: 10.1002/pi.4535] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Nebia Eschweiler
- DWI an der RWTH Aachen e.V. and Institute of Technical and Macromolecular Chemistry; RWTH Aachen; Forckenbeckstraße 50 D-52056 Aachen Germany
| | - Helmut Keul
- DWI an der RWTH Aachen e.V. and Institute of Technical and Macromolecular Chemistry; RWTH Aachen; Forckenbeckstraße 50 D-52056 Aachen Germany
| | - Marta Millaruelo
- Bayer MaterialScience AG; BMS-CD-NB-NT, Kaiser-Wilhelm-Allee; Geb K13 D51368 Leverkusen Germany
| | - Ralf Weberskirch
- TU Dortmund, Fakultät Chemie; Otto-Hahn-Weg 6 D-44227 Dortmund Germany
| | - Martin Moeller
- DWI an der RWTH Aachen e.V. and Institute of Technical and Macromolecular Chemistry; RWTH Aachen; Forckenbeckstraße 50 D-52056 Aachen Germany
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13
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Yip AK, Iwasaki K, Ursekar C, Machiyama H, Saxena M, Chen H, Harada I, Chiam KH, Sawada Y. Cellular response to substrate rigidity is governed by either stress or strain. Biophys J 2013; 104:19-29. [PMID: 23332055 DOI: 10.1016/j.bpj.2012.11.3805] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Revised: 11/19/2012] [Accepted: 11/26/2012] [Indexed: 12/18/2022] Open
Abstract
Cells sense the rigidity of their substrate; however, little is known about the physical variables that determine their response to this rigidity. Here, we report traction stress measurements carried out using fibroblasts on polyacrylamide gels with Young's moduli ranging from 6 to 110 kPa. We prepared the substrates by employing a modified method that involves N-acryloyl-6-aminocaproic acid (ACA). ACA allows for covalent binding between proteins and elastomers and thus introduces a more stable immobilization of collagen onto the substrate when compared to the conventional method of using sulfo-succinimidyl-6-(4-azido-2-nitrophenyl-amino) hexanoate (sulfo-SANPAH). Cells remove extracellular matrix proteins off the surface of gels coated using sulfo-SANPAH, which corresponds to lower values of traction stress and substrate deformation compared to gels coated using ACA. On soft ACA gels (Young's modulus <20 kPa), cell-exerted substrate deformation remains constant, independent of the substrate Young's modulus. In contrast, on stiff substrates (Young's modulus >20 kPa), traction stress plateaus at a limiting value and the substrate deformation decreases with increasing substrate rigidity. Sustained substrate strain on soft substrates and sustained traction stress on stiff substrates suggest these may be factors governing cellular responses to substrate rigidity.
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Affiliation(s)
- Ai Kia Yip
- Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore
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14
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Lakins JN, Chin AR, Weaver VM. Exploring the link between human embryonic stem cell organization and fate using tension-calibrated extracellular matrix functionalized polyacrylamide gels. Methods Mol Biol 2012; 916:317-350. [PMID: 22914951 DOI: 10.1007/978-1-61779-980-8_24] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Human embryonic stem cell (hESc) lines are likely the in vitro equivalent of the pluripotent epiblast. hESc express high levels of the extracellular matrix (ECM) laminin integrin receptor α6β1 and consequently can adhere robustly and be propagated in an undifferentiated state on tissue culture plastic coated with the laminin rich basement membrane preparation, Matrigel, even in the absence of supporting fibroblasts. Such cultures represent a critical step in the development of more defined feeder free cultures of hESc; a goal deemed necessary for regenerative medical applications and have been used as the starting point in some differentiation protocols. However, on standard non-deformable tissue culture plastic hESc either fail or inadequately develop the structural/morphological organization of the epiblast in vivo. By contrast, growth of hESc on appropriately defined mechanically deformable polyacrylamide substrates permits recapitulation of many of these in vivo features. These likely herald differences in the precise nature of the integration of signal transduction pathways from soluble morphogens and represent an unexplored variable in hESc (fate) state space. In this chapter we describe how to establish viable hESc colonies on these functionalized polyacrylamide gels. We suggest this strategy as a prospective in vitro model of the genetics, biochemistry, and cell biology of pre- and early-gastrulation stage human embryos and the permissive and instructive roles that cellular and substrate mechanics might play in early embryonic cell fate decisions. Such knowledge should inform regenerative medical applications aimed at enabling or improving the differentiation of specific cell types from embryonic or induced embryonic stem cells.
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Affiliation(s)
- Johnathon N Lakins
- Department of Surgery, Center for Bioengineering and Tissue Regeneration, University of California, San Francisco, San Francisco, CA, USA
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15
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Kraning-Rush CM, Carey SP, Califano JP, Reinhart-King CA. Quantifying Traction Stresses in Adherent Cells. Methods Cell Biol 2012; 110:139-78. [DOI: 10.1016/b978-0-12-388403-9.00006-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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16
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Shebanova O, Hammer DA. Biochemical and mechanical extracellular matrix properties dictate mammary epithelial cell motility and assembly. Biotechnol J 2011; 7:397-408. [PMID: 22121055 DOI: 10.1002/biot.201100188] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Revised: 10/07/2011] [Accepted: 11/18/2011] [Indexed: 01/22/2023]
Abstract
Biochemical and mechanical cues of the extracellular matrix have been shown to play important roles in cell-matrix and cell-cell interactions. We have experimentally tested the combined influence of these cues to better understand cell motility, force generation, cell-cell interaction, and assembly in an in vitro breast cancer model. MCF-10A non-tumorigenic mammary epithelial cells were observed on surfaces with varying fibronectin ligand concentration and polyacrylamide gel rigidity. Our data show that cell velocity is biphasic in both matrix rigidity and adhesiveness. The maximum cell migration velocity occurs only at specific combination of substrate stiffness and ligand density. We found cell-cell interactions reduce migration velocity. However, the traction forces cells exert onto the substrate increase linearly with both cues, with cells in pairs exerting higher maximum tractions observed over single cells. A relationship between force and motility shows a maximum in single cell velocity not observed in cell pairs. Cell-cell adhesion becomes strongly favored on softer gels with elasticity ≤ 1250 Pascals (Pa), implying the existence of a compliance threshold that promotes cell-cell over cell-matrix adhesion. Finally on gels with stiffness similar to pre-malignant breast tissue, 400 Pa, cells undergo multicellular assembly and division into 3D spherical aggregates on a 2D surface.
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Affiliation(s)
- Olga Shebanova
- Department of Chemical and Biomolecular Engineering, Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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17
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Traction forces of neutrophils migrating on compliant substrates. Biophys J 2011; 101:575-84. [PMID: 21806925 DOI: 10.1016/j.bpj.2011.05.040] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 04/29/2011] [Accepted: 05/03/2011] [Indexed: 11/23/2022] Open
Abstract
Proper functioning of the innate immune response depends on migration of circulating neutrophils into tissues at sites of infection and inflammation. Migration of highly motile, amoeboid cells such as neutrophils has significant physiological relevance, yet the traction forces that drive neutrophil motion in response to chemical cues are not well characterized. To better understand the relationship between chemotactic signals and the organization of forces in motile neutrophils, force measurements were made on hydrogel surfaces under well-defined chemotactic gradients created with a microfluidic device. Two parameters, the mean chemoattractant concentration (C(M)) and the gradient magnitude (Δc/Δx) were varied. Cells experiencing a large gradient with C(M) near the chemotactic receptor K(D) displayed strong punctate centers of uropodial contractile force and strong directional motion on stiff (12 kPa) surfaces. Under conditions of ideal chemotaxis--cells in strong gradients with mean chemoattractant near the receptor K(D) and on stiffer substrates--there is a correlation between the magnitude of force generation and directional motion as measured by the chemotactic index. However, on soft materials or under weaker chemotactic conditions, directional motion is uncorrelated with the magnitude of traction force. Inhibition of either β(2) integrins or Rho-associated kinase, a kinase downstream from RhoA, greatly reduced rearward traction forces and directional motion, although some vestigial lamellipodium-driven motility remained. In summary, neutrophils display a diverse repertoire of methods for organizing their internal machinery to generate directional motion.
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18
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Charest JM, Califano JP, Carey SP, Reinhart-King CA. Fabrication of substrates with defined mechanical properties and topographical features for the study of cell migration. Macromol Biosci 2011; 12:12-20. [PMID: 22021131 DOI: 10.1002/mabi.201100264] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/08/2011] [Indexed: 11/06/2022]
Abstract
Both substrate topography and substrate mechanical properties are known to influence cell behavior, but little is known about how they act in concert. Here, a method is presented to introduce topographical features into PA hydrogel substrates that span a wide range of physiological E values. Gel swelling plays a significant role in the fidelity of protruding micromolded features, with the most efficient pattern transfer occurring at a crosslinking concentration equal to or greater than ≈5%. In contrast, swelling does not influence the spacing fidelity of microcontact printed islands of collagen on 2D PA substrates. BAECs cultured on micromolded PA substrates exhibit contact guidance along ridges patterned for all E tested.
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19
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Kelly DM, Moynihan HA. Synthesis and evaluation of fully (5-amidoisophthalic acid)-functionalised polyacrylamides as selective inhibitors of the beta crystal polymorph of l-glutamic acid. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.05.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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20
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Jannat RA, Dembo M, Hammer DA. Neutrophil adhesion and chemotaxis depend on substrate mechanics. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:194117. [PMID: 20473350 PMCID: PMC2867619 DOI: 10.1088/0953-8984/22/19/194117] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Neutrophil adhesion to the vasculature and chemotaxis within tissues play critical roles in the inflammatory response to injury and pathogens. Unregulated neutrophil activity has been implicated in the progression of numerous chronic and acute diseases such as rheumatoid arthritis, asthma, and sepsis. Cell migration of anchorage-dependent cells is known to depend on both chemical and mechanical interactions. Although neutrophil responses to chemical cues have been well characterized, little is known about the effect of underlying tissue mechanics on neutrophil adhesion and migration. To address this question, we quantified neutrophil migration and traction stresses on compliant hydrogel substrates with varying elasticity in a micro-machined gradient chamber in which we could apply either a uniform concentration or a precise gradient of the bacterial chemoattractant fMLP. Neutrophils spread more extensively on substrates of greater stiffness. In addition, increasing the stiffness of the substrate leads to a significant increase in the chemotactic index for each fMLP gradient tested. As the substrate becomes stiffer, neutrophils generate higher traction forces without significant changes in cell speed. These forces are often displayed in pairs and focused in the uropod. Increases in the mean fMLP concentration beyond the K(D) of the receptor lead to a decrease in chemotactic index on all surfaces. Blocking with an antibody against beta(2)-integrins leads to a significant reduction but not an elimination of directed motility on stiff materials, but no change in motility on soft materials, suggesting neutrophils can display both integrin-dependent and integrin-independent motility. These findings are critical for understanding how neutrophil migration may change in different mechanical environments in vivo and can be used to guide the design of migration inhibitors that more efficiently target inflammation.
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Affiliation(s)
- Risat A. Jannat
- Department of Bioengineering University of Pennsylvania 240 Skirkanich Hall 210 S. 33 Street Philadelphia, PA 19104
| | - Micah Dembo
- Department of Biomedical Engineering Boston University 44 Cummington St. Boston, MA 02215
| | - Daniel A. Hammer
- Department of Bioengineering University of Pennsylvania 240 Skirkanich Hall 210 S. 33 Street Philadelphia, PA 19104
- Department of Chemical and Biomolecular Engineering University of Pennsylvania 311A Towne Building 220 South 33 Street Philadelphia, PA 19104
- To whom correspondence should be addressed at: Department of Bioengineering University of Pennsylvania 240 Skirkanich Hall 210 S. 33 Street Philadelphia, PA 19104 Office: 215-573-6761 Fax: 215-573-2071
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21
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Califano JP, Reinhart-King CA. The effects of substrate elasticity on endothelial cell network formation and traction force generation. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:3343-5. [PMID: 19964074 DOI: 10.1109/iembs.2009.5333194] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
While the growth factors and cytokines known to influence angiogenesis and vasculogenesis have garnered widespread attention, less is known about how the mechanical environment affects blood vessel formation and cell assembly. In this study, we investigate the relationship between substrate elasticity, endothelial cell-cell connectivity and traction force generation. We find that on more compliant substrates, endothelial cells self-assemble into network-like structures independently of additional exogenous growth factors or cytokines. These networks form from the assembly of sub-confluent endothelial cells on compliant (E = 200-1000Pa) substrates, and results from both the proliferation and migration of endothelial cells. Interestingly, stabilization of these cell-cell connections and networks requires fibronectin polymerization. Traction Force Microscopy measurements indicate that individual endothelial cells on compliant substrates exert forces which create substrate stains that propagate from the cell edge. We speculate that these strains draw the cells together and initiate self-assembly. Notably, endothelial cell network formation on compliant substrates is dynamic and transient; as cell number and substrate strains increase, the networks fill in through collective cell movements from the network edges. Our results indicate that network formation is mediated in part by substrate mechanics and that cellular traction force may promote cell-cell assembly by directing cell migration.
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22
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Abstract
Angiogenesis is the process by which endothelial cells grow and disassemble into functional blood vessels. In this study, we examine the fundamental processes that control the assembly of endothelial cells into networks in vitro. Network assembly is known to be influenced by matrix mechanics and chemical signals. However, the roles of substrate stiffness and chemical signals in network formation is unclear. In this study, human umbilical vein endothelial cells (HUVECs) were seeded onto RGD or GFOGER functionalized polyacrylamide gels of varying stiffness. Cells were either treated with bFGF, VEGF, or left untreated and observed over time. We found that cells form stable networks on soft gels (Young's modulus 140 Pa) when untreated but that growth factors induce increased cell migration which leads to network instability. On stiffer substrates (Young's modulus 2500 Pa) cells do not assemble into networks either with or without growth factors in any combination. Our results indicate that cells assemble to networks below a critical compliance, that a critical cell density is needed for network formation, and that growth factors can inhibit network formation through an increase in motility.
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23
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24
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Califano JP, Reinhart-King CA. Substrate Stiffness and Cell Area Predict Cellular Traction Stresses in Single Cells and Cells in Contact. Cell Mol Bioeng 2010; 3:68-75. [PMID: 21116436 DOI: 10.1007/s12195-010-0102-6] [Citation(s) in RCA: 210] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Cells generate traction stresses against their substrate during adhesion and migration, and traction stresses are used in part by the cell to sense the substrate. While it is clear that traction stresses, substrate stiffness, and cell area are related, it is unclear whether or how area and substrate stiffness affect force generation in cells. Moreover, multiple studies have investigated traction stresses of single cells, but few have focused on forces exerted by cells in contact, which more closely mimics the in vivo environment. Here, cellular traction forces were measured where cell area was modulated by ligand density or substrate stiffness. We coupled these measurements with a multilinear regression model to show that both projected cell area and underlying substrate stiffness are significant predictors of traction forces in endothelial cells, and interestingly, substrate ligand density is not. We further explored the effect of cell-cell contact on the interplay between cell area, substrate stiffness, and force generation and found that again both area and stiffness play a significant role in cell force generation. These data indicate that cellular traction force cannot be determined by cell area alone and that underlying substrate stiffness is a significant contributor to traction force generation.
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Affiliation(s)
- Joseph P Califano
- Department of Biomedical Engineering, Cornell University, 302 Weill Hall, 526 Campus Rd., Ithaca, NY 14853, USA
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25
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Califano JP, Reinhart-King CA. Exogenous and endogenous force regulation of endothelial cell behavior. J Biomech 2010; 43:79-86. [DOI: 10.1016/j.jbiomech.2009.09.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2009] [Indexed: 01/08/2023]
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26
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A Balance of Substrate Mechanics and Matrix Chemistry Regulates Endothelial Cell Network Assembly. Cell Mol Bioeng 2008. [DOI: 10.1007/s12195-008-0022-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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27
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Abstract
The role of matrix mechanics on cell behavior is under intense investigation. Cells exert contractile forces on their matrix and the matrix elasticity can alter these forces and cell migratory behavior. However, little is known about the contribution of matrix mechanics and cell-generated forces to stable cell-cell contact and tissue formation. Using matrices of varying stiffness and measurements of endothelial cell migration and traction stresses, we find that cells can detect and respond to substrate strains created by the traction stresses of a neighboring cell, and that this response is dependent on matrix stiffness. Specifically, pairs of endothelial cells display hindered migration on gels with elasticity below 5500 Pa in comparison to individual cells, suggesting these cells sense each other through the matrix. We believe that these results show for the first time that matrix mechanics can foster tissue formation by altering the relative motion between cells, promoting the formation of cell-cell contacts. Moreover, our data indicate that cells have the ability to communicate mechanically through their matrix. These findings are critical for the understanding of cell-cell adhesion during tissue formation and disease progression, and for the design of biomaterials intended to support both cell-matrix and cell-cell adhesion.
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28
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29
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Kandow CE, Georges PC, Janmey PA, Beningo KA. Polyacrylamide Hydrogels for Cell Mechanics: Steps Toward Optimization and Alternative Uses. Methods Cell Biol 2007; 83:29-46. [PMID: 17613303 DOI: 10.1016/s0091-679x(07)83002-0] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Since their first introduction, polyacrylamide hydrogels have proven to be very useful for studies of mechanical interactions at the cell-substrate interface. In this chapter, we briefly review the basic concepts of this method and provide a series of modifications that have evolved since its inception. In addition, we have described several alternative uses of polyacrylamide hydrogels that have emerged for the study of cellular mechanics. Our intention is to provide users of this gel system with a number of improved and tested options as this method advances toward optimization.
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Affiliation(s)
- Casey E Kandow
- Department of Biology, Wayne State University, Detroit, Michigan 48202, USA
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30
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Johnson KR, Leight JL, Weaver VM. Demystifying the effects of a three-dimensional microenvironment in tissue morphogenesis. Methods Cell Biol 2007; 83:547-83. [PMID: 17613324 PMCID: PMC2658721 DOI: 10.1016/s0091-679x(07)83023-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Tissue morphogenesis and homeostasis are dependent on a complex dialogue between multiple cell types and chemical and physical cues in the surrounding microenvironment. The emergence of engineered three-dimensional (3D) tissue constructs and the development of tractable methods to recapitulate the native tissue microenvironment ex vivo has led to a deeper understanding of tissue-specific behavior. However, much remains unclear about how the microenvironment and aberrations therein directly affect tissue morphogenesis and behavior. Elucidating the role of the microenvironment in directing tissue-specific behavior will aid in the development of surrogate tissues and tractable approaches to diagnose and treat chronic-debilitating diseases such as cancer and atherosclerosis. Toward this goal, 3D organotypic models have been developed to clarify the mechanisms of epithelial morphogenesis and the subsequent maintenance of tissue homeostasis. Here we describe the application of these 3D culture models to illustrate how the microenvironment plays a critical role in regulating mammary tissue function and signaling, and discuss the rationale for applying precisely defined organotypic culture assays to study epithelial cell behavior. Experimental methods are provided to generate and manipulate 3D organotypic cultures to study the effect of matrix stiffness and matrix dimensionality on epithelial tissue morphology and signaling. We end by discussing technical limitations of currently available systems and by presenting opportunities for improvement.
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Affiliation(s)
- Kandice R Johnson
- Institute for Medicine and Engineering, Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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31
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Auernheimer J, Haubner R, Schottelius M, Wester HJ, Kessler H. Radio-Analytical Determination of the Coating Efficiency of Cyclic RGD Peptides. Helv Chim Acta 2006. [DOI: 10.1002/hlca.200690085] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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32
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Auernheimer J, Dahmen C, Hersel U, Bausch A, Kessler H. Photoswitched Cell Adhesion on Surfaces with RGD Peptides. J Am Chem Soc 2005; 127:16107-10. [PMID: 16287297 DOI: 10.1021/ja053648q] [Citation(s) in RCA: 196] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Coating of surfaces by RGD peptides is well-known. Herein we describe the possibility to switch cell adhesion properties by changing the distance and orientation of the RGD peptides to the surface. A set of RGD peptides of the type cyclo(-RGDfK-) was synthesized containing the photoswitchable 4-[(4-aminophenyl)azo]benzocarbonyl central unit as spacer between the acrylamide anchor and the RGD peptide. PMMA (poly methyl methacrylate) surfaces were coated with these peptides. Control of adhesion stimulation by irradiation with 366 or 450 nm light could be achieved.
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Affiliation(s)
- Jörg Auernheimer
- Department Chemie, Lehrstuhl II für Organische Chemie, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany
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33
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Abstract
Cell adhesion to extracellular matrix is mediated by receptor-ligand interactions. When a cell first contacts a surface, it spreads, exerting traction forces against the surface and forming new bonds as its contact area expands. Here, we examined the changes in shape, actin polymerization, focal adhesion formation, and traction stress generation that accompany spreading of endothelial cells over a period of several hours. Bovine aortic endothelial cells were plated on polyacrylamide gels derivatized with a peptide containing the integrin binding sequence RGD, and changes in shape and traction force generation were measured. Notably, both the rate and extent of spreading increase with the density of substrate ligand. There are two prominent modes of spreading: at higher surface ligand densities cells tend to spread isotropically, whereas at lower densities of ligand the cells tend to spread anisotropically, by extending pseudopodia randomly distributed along the cell membrane. The extension of pseudopodia is followed by periods of growth in the cell body to interconnect these extensions. These cycles occur at very regular intervals and, furthermore, the extent of pseudopodial extension can be diminished by increasing the ligand density. Measurement of the traction forces exerted by the cell reveals that a cell is capable of exerting significant forces before either notable focal adhesion or stress fiber formation. Moreover, the total magnitude of force exerted by the cell is linearly related to the area of the cell during spreading. This study is the first to monitor the dynamic changes in the cell shape, spreading rate, and forces exerted during the early stages (first several hours) of endothelial cell adhesion.
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Affiliation(s)
- Cynthia A Reinhart-King
- Department of Bioengineering and Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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34
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Kantlehner M, Finsinger D, Meyer J, Schaffner P, Jonczyk A, Diefenbach B, Nies B, Kessler H. Selektive RGD-vermittelte Adhäsion von Osteoblasten an Implantat-Oberflächen. Angew Chem Int Ed Engl 1999. [DOI: 10.1002/(sici)1521-3757(19990215)111:4<587::aid-ange587>3.0.co;2-n] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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35
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Swift DG, Posner RG, Hammer DA. Kinetics of adhesion of IgE-sensitized rat basophilic leukemia cells to surface-immobilized antigen in Couette flow. Biophys J 1998; 75:2597-611. [PMID: 9788956 PMCID: PMC1299935 DOI: 10.1016/s0006-3495(98)77705-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Antigen-antibody systems provide the flexibility of varying the kinetics and affinity of molecular interaction and studying the resulting effect on adhesion. In a parallel-plate flow chamber, we measured the extent and rate of adhesion of rat basophilic leukemia cells preincubated with anti-dinitrophenyl IgE clones SPE-7 or H1 26. 82 to dinitrophenyl-coated polyacrylamide gel substrates in a linear shear field. Both of these IgEs bind dinitrophenyl, but H1 26.82 has a 10-fold greater on rate and a 30-fold greater affinity. Adhesion was found to be binary; cells either arrested irreversibly or continued at their unencumbered hydrodynamic velocity. Under identical conditions, more adhesion was seen with the higher affinity (higher on rate) IgE clone. At some shear rates, adhesion was robust with H1 26.82, but negligible with SPE-7. Reduction in receptor number or ligand density reduced the maximum level of adhesion seen at any shear rate, but did not decrease the shear rate at which adhesion was first observed. The spatial pattern of adhesion for both IgE clones is well represented by the first-order kinetic rate constant kad, and we have determined how kad depends on ligand and receptor densities and shear rate. The rate constant kad found with H1 26.82 was approximately fivefold greater than with SPE-7. The dependence of kad on site density and shear rate for SPE-7 is complex: kad increases linearly with antigen site density at low to moderate shear rates, but is insensitive to site density at high shear. kad increases with shear rate at low site density but decreases with shear at high site density. With H1 26.82, the functional dependence of kad with shear rate was similar. Although these data are consistent with the hypothesis that we have sampled both transport and reaction-limited adhesion regimes, they point out deficiencies in current theories describing cell attachment under flow.
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Affiliation(s)
- D G Swift
- Department of Chemical Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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36
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Kunitsyn A, Kochetkova S, Kolganova N, Tishchenko E, Gottikh B, Florentiev V. Stabilizating effect of 5-nitroindole (universal base) on DNA duplexes immobilized on gel matrix. J Biomol Struct Dyn 1997; 15:597-603. [PMID: 9440005 DOI: 10.1080/07391102.1997.10508969] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Effect of attachment of 1-(2-deoxy-beta-D-ribofuranosyl)-5-nitroindole (NIDR) to the ends of target sequence of oligonucleotides immobilized on gel micromatrix on stability of duplex formed by hybridization with DNA fragment was studied. It was shown that adjunction of NIDR to 5' as well as to 3' end results in increasing stability of duplexes although in the second case the extent of stabilization effect is essentially lower. Both 5' and 3' terminal NIDR exhibited no selectivity to the opposite base while the stabilizing effect depended dramatically on the nature of the adjacent base especially in the case of 5'-end-attached universal base. The neighborhood of purine bases decreased substantially the stabilizing effect of 5' terminal NIDR. In contrast with this, the stabilizing effect of 3' terminal NIDR was reduced only slightly by adjacent pyrimidine bases.
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Affiliation(s)
- A Kunitsyn
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russian Federation
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37
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Kunitsyn A, Kochetkova S, Timofeev E, Florentiev V. Partial thermodynamic parameters for prediction stability and washing behavior of DNA duplexes immobilized on gel matrix. J Biomol Struct Dyn 1996; 14:239-44. [PMID: 8913861 DOI: 10.1080/07391102.1996.10508114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Earlier we showed that reported in literature nearest-neighbor thermodynamic parameters describe poorly the thermal-induced behavior of DNA duplexes immobilized in gel. Here we present a complete set of partial thermodynamic parameters for all 10 nearest-neighbor interactions specially developed for duplexes immobilized in gel. This thermodynamic library allows to predict dissociation enthalpy and free energy of DNA duplex immobilized in gel matrix from its base sequence. The predicted values are in good agreement with the experimental ones. Dissociation enthalpy and free energy are needed for such application as (i) predicting relative stability of duplexes formed by DNA with oligonucleotides immobilized in cells of gel matrix; (ii) selecting optimal conditions for hybridization experiment; (iii) predicting washing curves and washing temperatures at irreversible temperature-stepped wash of DNA out of oligonucleotide gel matrix; (iv) selecting optimal conditions for washing gel matrix.
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Affiliation(s)
- A Kunitsyn
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russian Federation
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38
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Csanaky G, Vass JA, Ocsovszki I, Milosevits J, Szomor A, Schmelczer M. Changes in adhesion molecule expression and function in B-cell chronic lymphocytic leukaemia after in vitro interferon-alpha stimulation. Eur J Haematol 1995; 54:27-33. [PMID: 7532138 DOI: 10.1111/j.1600-0609.1995.tb01622.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Peripheral blood mononuclear cells (PBMCs) from 10 B-CLL patients were investigated after 24 hours of in vitro interferon-alpha (IFN-alpha) stimulation. The constitutional expression of the L-selectins (LECAM-1), LFA-1/CD11a, VLA alpha-4/CDw49d and ICAM-1/CD54 adhesion molecules was detected, and changes in their density after IFN-alpha stimulation were compared to results obtained by the high endothelial venule (HEV)-binding assay and a carbohydrate (phosphonomannan core polysaccharide: PPME and fucoidin) immobilization test. The LECAM-1 and ICAM-1 molecules were expressed on the great majority of CLL cells, while the LFA-1 and VLA-4 alpha-chains were expressed by only a small number of cells. Statistically significant changes (p < 0.001) were observed in LECAM-1 antigen density (changes in mean cell fluorescence), as well as in functional tests (HEV-, PPME- and fucoidin-binding; p < 0.01) after in vitro IFN-alpha stimulation. Based on a prior study (Jewell et al., Leukemia 1992: 6: 400-404) and on the present findings, not only an increased expression but also an enhanced function of the L-selectins seem to be well substantiated after IFN-alpha stimulation, which may explain the therapeutic effect of IFN-alpha in reducing the accumulation of leukaemic B cells in the blood. The remarkably high expression of ICAM-1 in this series necessitates further studies to clarify the exact expression rate and role of this molecule.
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Affiliation(s)
- G Csanaky
- Department of Pathology, University Medical School of Pécs, Hungary
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39
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Csanaky G, Vass JA, Losonczy H, Schmelczer M. Expression of an adhesion molecule and homing in B-cell chronic lymphocytic leukaemia: II. L-selectin expression mediated cell adhesion revealed by immobilized analogue carbohydrates in B-cell chronic lymphocytic leukaemia and monoclonal lymphocytosis of undetermined significance. MEDICAL ONCOLOGY AND TUMOR PHARMACOTHERAPY 1993; 10:173-80. [PMID: 8164454 DOI: 10.1007/bf02989666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The L-selectin mediated adhesion of freshly isolated peripheral blood mononuclear cells (PBMCs) to phosphonomonoester core polysaccharide (PPME) and fucoidin derivatized gels was investigated in seven cases of monoclonal lymphocytosis of undetermined significance (B-MLUS) and 12 cases of chronic lymphocytic leukaemia: B-CLL, patients with peripheral lymphocytosis (LY-patients), lymph node enlargement (LN-patients) and splenomegaly (SM-patients). PBMCs isolated from the peripheral blood of 10 healthy donors served as controls. The binding to PPME and fucoidin correlated well (n = 19, P = 0.01). Adhesion of PBMCs from B-MLUS and B-CLL showed a greater variability than controls. A higher number of cells, on average, bound to PPME and fucoidin derivatized polyacrylamide gels in B-MLUS than in B-CLL. However, the differences observed were not statistically significant. In four cases with B-CLL, the stimulatory effect of interferon-alpha on the function of L-selectin and some other accessory molecules was also studied. The increased binding of PBMCs to immobilized analogue molecules (PPME, fucoidin) and to high endothelial venules (HEVs) in the in vitro HEV-binding assay supports the notion that interferon-alpha not only increases the expression of the adhesion molecules, but also results in an enhanced adhesive function.
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Affiliation(s)
- G Csanaky
- Department of Pathology, University Medical School of Pécs, Hungary
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40
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Koopmann J, Hocke J, Gabius HJ. Gel-immobilized heparin-binding lectin as sensitive sensor for certain groups of charge-bearing carbohydrates. BIOLOGICAL CHEMISTRY HOPPE-SEYLER 1993; 374:1029-32. [PMID: 8292261 DOI: 10.1515/bchm3.1993.374.7-12.1029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The specificity of lectins to carbohydrate moieties in principle enables them to serve as sensors for sugars with ligand properties. However, experimental systems and parameters to measure this interaction need to be defined. On the basis of knowledge about temperature-sensitive volume changes of gels, composed of acrylamide derivatives, and about the influence of presence of charge-bearing groups within the gel on this behavior, we covalently immobilized a human heparin-binding lectin into a gel matrix. Besides the lectin-carrying derivative N-isopropylacrylamide and N,N'-methylenebisacrylamide are the monomeric constituents of the polymer. The lectin has been attached to divinyl sulfone-activated N-hydroxymethylacrylamide. Several anionic sugar moieties are added to the solution, covering the gel pieces, and the mechanical response of the individual gel slices in dependence to stepwise temperature increases is automatically recorded with an electronic transducer at a sensitivity of 5 mV/microns. Only carboxyl group-containing sugar moieties like glucuronic acid notably reduce the extent of the temperature-dependent gel shrinking as indicator for a protein-carbohydrate interaction. The individual slices are reuseable, emphasizing practical applications. This sensitive and automated assay concept with the covalently immobilized heparin-binding protein is supposed to be adaptable to other groups of lectins with specificity to anionic sugars like sialic acid-binding proteins.
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Affiliation(s)
- J Koopmann
- Institut für Physiologische Chemie, Ludwig-Maximilians-Universität, München, Germany
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41
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Yu C, Lee A, Bassler B, Roseman S. Chitin utilization by marine bacteria. A physiological function for bacterial adhesion to immobilized carbohydrates. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54223-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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42
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Gabius HJ. Detection and functions of mammalian lectins--with emphasis on membrane lectins. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1071:1-18. [PMID: 2004115 DOI: 10.1016/0304-4157(91)90010-t] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- H J Gabius
- Max-Planck-Institut für experimentelle Medizin, Abteilung Chemie, Göttingen, F.R.G
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43
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The species-specific cell-binding site of the aggregation factor from the sponge Microciona prolifera is a highly repetitive novel glycan containing glucuronic acid, fucose, and mannose. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)30541-0] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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44
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Abstract
A homogeneous glycidyl acrylate polymer (GAP) has been grafted on to polytetrafluoroethylene (PTFE) and polyethylene (PE) using a modified plasma glow discharge technique with glycidyl acrylate. The polymeric layer appears to be extremely stable to acidic media and to common organic solvents. The modified surface can be derivatized via epoxy groups with hydroxy and amino compounds including sugars and amino sugars. These derivatized surfaces have been characterized by Fourier transform infrared (FTIR) spectroscopy and contact angle measurements. The wide variety of compounds which can be attached provides flexibility in the design of surfaces for the study of a range of biological interactions.
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Affiliation(s)
- F Tanfani
- Department of Protein and Molecular Biology, Royal Free Hospital School of Medicine, London, UK
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45
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Abstract
Polyacrylamide surfaces covalently derivatized with quantifiable gradients of glycosides superimposed on a uniform adhesive background of coimmobilized Arg-Gly-Asp-containing adhesion peptide were synthesized. Substrate-directed cell redistribution (haptotaxis) was measured by seeding derivatized surfaces uniformly with B16F10 murine melanoma cells. After 4-32 hr, cells on gradients of N-acetylglucosamine (GlcNAc) redistributed markedly; higher cell densities were found at gel positions having a higher immobilized GlcNAc density. In contrast, cells seeded on otherwise identical gels having a uniform concentration of immobilized GlcNAc, or on gels having gradients of glucose or galactose, did not redistribute. Soluble inhibitors containing nonreducing terminal GlcNAc (but not those with terminal GalNAc or Gal) blocked redistribution on immobilized GlcNAc gradients. Redistribution was not affected by the presence or absence of serum in the medium. An affinity-purified antibody against beta-1,4-galactosyltransferase, a GlcNAc-binding protein reported to be expressed on B16F10 cell surfaces, attenuated GlcNAc-directed redistribution. When cells were seeded on surfaces derivatized with various uniform densities of immobilized GlcNAc coimmobilized with an invariant density of immobilized Arg-Gly-Asp-peptide, neither cell attachment nor proliferation rate were enhanced on the gels having a higher GlcNAc density. These data indicate that the redistribution on immobilized GlcNAc gradients was due to cell motility. Although gels derivatized with Arg-Gly-Asp-peptide alone supported strong B16F10 cell adhesion, surfaces derivatized with uniform high concentrations of GlcNAc did not. We conclude that cell recognition of substratum gradients that support, at best, weak adhesion (GlcNAc) on an otherwise uniform strongly adhesive background (Arg-Gly-Asp-peptide) may be sufficient to direct cell migration.
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Affiliation(s)
- B K Brandley
- Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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46
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Brandley BK, Schnaar RL. Tumor cell haptotaxis on covalently immobilized linear and exponential gradients of a cell adhesion peptide. Dev Biol 1989; 135:74-86. [PMID: 2767336 DOI: 10.1016/0012-1606(89)90159-0] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The movement of cells up an adhesive substratum gradient has been proposed as a mechanism for directing cell migration during development and metastasis. Critical evaluation of this hypothesis (haptotaxis) benefits from the use of quantifiable, stable substratum gradients of biologically relevant adhesion molecules. We report covalent derivatization of polyacrylamide surfaces with quantifiable gradients of a nonapeptide containing the adhesive Arg-Gly-Asp sequence. Cell migration was studied by seeding derivatized surfaces evenly with B16F10 murine melanoma cells. Within 8 hr, cells on gradients redistributed markedly; higher cell densities were found at gel positions having higher immobilized peptide densities. In contrast, cells seeded on control gels with uniform concentrations of adhesive peptide did not redistribute. Redistribution occurred on gradients in both serum-free and serum-containing media. Experiments with uniform density peptide-derivatized gels demonstrated that redistribution on gradients was not due to preferential initial cell attachment or preferential growth on the higher density of immobilized peptide, but must have been due to cell translocation. Cells on exponential gradients of immobilized peptide migrated to a position on the gel surface corresponding to the highest immobilized peptide density, while cells on linear gradients of the same peptide migrated to a position of intermediate peptide density. These data suggest that the B16F10 cells respond to proportional changes in immobilized peptide density rather than to absolute changes, implying a sensing mechanism which utilizes adaptation. These results demonstrate that (1) a gradient of a small adhesive peptide is sufficient to generate redistribution of cell populations and (2) controlled quantifiable substratum gradients can be produced and used to probe the underlying cellular mechanisms of this behavior.
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Affiliation(s)
- B K Brandley
- Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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48
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Shivakumar K, Nair RR, Jayakrishnan A, Thanoo BC, Kartha CC. Synthetic hydrogel microspheres as substrata for cell adhesion and growth. IN VITRO CELLULAR & DEVELOPMENTAL BIOLOGY : JOURNAL OF THE TISSUE CULTURE ASSOCIATION 1989; 25:353-7. [PMID: 2715128 DOI: 10.1007/bf02624598] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cross-linked poly(methyl methacrylate) (PMMA) microspheres were subjected to alkaline hydrolysis to obtain hydrophilic microspheres having carboxyl residues distributed throughout the matrix. These microspheres were found to support the growth of human skin fibroblasts and human heart and lung cells. Further, fibroblasts grown on them were found to be comparable with those grown on the commercial tissue culture plate with respect to [14C]amino acid uptake and incorporation into proteins. The hydrolyzed PMMA microspheres may find application as a microcarrier for cell culture.
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Affiliation(s)
- K Shivakumar
- Division of Pathology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, India
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49
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Brandley BK, Schnaar RL. Covalent attachment of an Arg-Gly-Asp sequence peptide to derivatizable polyacrylamide surfaces: support of fibroblast adhesion and long-term growth. Anal Biochem 1988; 172:270-8. [PMID: 3189771 DOI: 10.1016/0003-2697(88)90442-3] [Citation(s) in RCA: 146] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
A synthetic nonapeptide (Tyr-Ala-Val-Thr-Gly-Arg-Gly-Asp-Ser), which includes the adhesive Arg-Gly-Asp (RGD) sequence, was covalently immobilized on chemically well-defined polyacrylamide gel surfaces utilizing N-succinimidyl active esters. The amount of peptide immobilized varied linearly with the concentration added to the gels. Immobilization was approximately 80% efficient (based on peptide added), resulting in up to 17.5 nmol peptide/cm2 gel surface. Balb/c 3T3 mouse fibroblast cells adhered readily to peptide-derivatized surfaces, even in the absence of serum. Furthermore, surfaces derivatized with 2 nmol peptide/cm2 gel supported long-term fibroblast growth at a rate and to an extent comparable to that on tissue culture plastic. Surfaces derivatized with a control nonapeptide having no RGD sequence were nonsupportive of cell attachment or growth. The immobilization technology used to derivatize the gel surfaces with adhesive nonapeptide can be modified to allow coderivatization with proteins, glycoproteins, glycosides, or other amine-containing compounds to test their effects on long-term cell behaviors.
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Affiliation(s)
- B K Brandley
- Department of Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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50
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Yu C, Lee AM, Roseman S. The sugar-specific adhesion/deadhesion apparatus of the marine bacterium Vibrio furnissii is a sensorium that continuously monitors nutrient levels in the environment. Biochem Biophys Res Commun 1987; 149:86-92. [PMID: 3689420 DOI: 10.1016/0006-291x(87)91608-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Our earlier studies on cell adhesion to immobilized carbohydrates are extended here to a marine bacterium, Vibrio furnissii. Apparently one lectin mediates the binding of these cells to glycosides of N-acetylglucosamine, mannose, and glucose covalently linked to Agarose beads. Kinetic studies show that protein synthesis is required for initiating and for maintaining adhesion to the glycosides. Furthermore, a pro- mutant binds to GlcNAc-beads at Pro concentrations insufficient to support cell growth. Expression of the functional lectin therefore predominates under conditions of limiting protein synthesis. Thus, cells adhere to the sugars in an environment compatible with protein synthesis, and deadhere when depleted of any required nutrient, presumably to migrate to a more favorable locale. The adhesion-deadhesion apparatus thereby permits constant monitoring of the surrounding environment, comprising a "nutrient sensorium".
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Affiliation(s)
- C Yu
- McCollum-Pratt Institute, Johns Hopkins University, Baltimore, Maryland 21218
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