1
|
De La Pena A, Mukhtar M, Yokosawa R, Carrasquilla S, Simmons CS. Quantifying cellular forces: Practical considerations of traction force microscopy for dermal fibroblasts. Exp Dermatol 2021; 30:74-83. [PMID: 32767472 PMCID: PMC7769991 DOI: 10.1111/exd.14166] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/12/2020] [Accepted: 07/30/2020] [Indexed: 12/28/2022]
Abstract
Traction force microscopy (TFM) is a well-established technique traditionally used by biophysicists to quantify the forces adherent biological cells exert on their microenvironment. As image processing software becomes increasingly user-friendly, TFM is being adopted by broader audiences to quantify contractility of (myo)fibroblasts. While many technical reviews of TFM's computational mechanics are available, this review focuses on practical experimental considerations for dermatology researchers new to cell mechanics and TFM who may wish to implement a higher throughput and less expensive alternative to collagen compaction assays. Here, we describe implementation of experimental methods, analysis using open-source software and troubleshooting of common issues to enable researchers to leverage TFM for their investigations into skin fibroblasts.
Collapse
Affiliation(s)
| | | | | | | | - Chelsey S. Simmons
- Department of Mechanical and Aerospace Engineering
- J. Crayton Pruitt Department of Biomedical Engineering
- Division of Cardiovascular Medicine, University of Florida
| |
Collapse
|
2
|
Rossi A, Wistlich L, Heffels KH, Walles H, Groll J. Isotropic Versus Bipolar Functionalized Biomimetic Artificial Basement Membranes and Their Evaluation in Long-Term Human Cell Co-Culture. Adv Healthc Mater 2016; 5:1939-48. [PMID: 27283510 DOI: 10.1002/adhm.201600224] [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: 02/29/2016] [Revised: 04/21/2016] [Indexed: 01/19/2023]
Abstract
In addition to dividing tissues into compartments, basement membranes are crucial as cell substrates and to regulate cellular behavior. The development of artificial basement membranes is indispensable for the ultimate formation of functional engineered tissues; however, pose a challenge due to their complex structure. Herein, biodegradable electrospun polyester meshes are presented, exhibiting isotropic or bipolar bioactivation as a biomimetic and biofunctional model of the natural basement membrane. In a one-step preparation process, reactive star-shaped prepolymer additives, which generate a hydrophilic fiber surface, are electrospun with cell-adhesion-mediating peptides, derived from major components of the basement membrane. Human skin cells adhere to the functionalized meshes, and long-term co-culture experiments confirm that the artificial basement membranes recapitulate and preserve tissue specific functions. Several layers of immortalized human keratinocytes grow on the membranes, differentiating toward the surface and expressing typical epithelial markers. Fibroblasts migrate into the reticular lamina mimicking part of the mesh. Both cells types begin to produce extracellular matrix proteins and to remodel the initial membrane. It is shown at the example of skin that the artificial basement membrane design provokes biomimetic responses of different cell types and can thus be used as basis for the future development of basement membrane containing tissues.
Collapse
Affiliation(s)
- Angela Rossi
- Chair for Tissue Engineering and Regenerative Medicine; University of Würzburg; Translational Center Würzburg “Regenerative Therapies in Oncology and Musculoskeletal Diseases”; Würzburg Branch of the Fraunhofer Institute for Interfacial Engineering and Biotechnology; Röntgenring 11 97070 Würzburg Germany
- Chair for Functional Materials in Medicine and Dentistry; University of Würzburg; Pleicherwall 2 97070 Würzburg Germany
| | - Laura Wistlich
- Chair for Functional Materials in Medicine and Dentistry; University of Würzburg; Pleicherwall 2 97070 Würzburg Germany
| | - Karl-Heinz Heffels
- Chair for Functional Materials in Medicine and Dentistry; University of Würzburg; Pleicherwall 2 97070 Würzburg Germany
| | - Heike Walles
- Chair for Tissue Engineering and Regenerative Medicine; University of Würzburg; Translational Center Würzburg “Regenerative Therapies in Oncology and Musculoskeletal Diseases”; Würzburg Branch of the Fraunhofer Institute for Interfacial Engineering and Biotechnology; Röntgenring 11 97070 Würzburg Germany
| | - Jürgen Groll
- Chair for Functional Materials in Medicine and Dentistry; University of Würzburg; Pleicherwall 2 97070 Würzburg Germany
| |
Collapse
|
3
|
Pinzón-García AD, Cassini-Vieira P, Ribeiro CC, de Matos Jensen CE, Barcelos LS, Cortes ME, Sinisterra RD. Efficient cutaneous wound healing using bixin-loaded PCL nanofibers in diabetic mice. J Biomed Mater Res B Appl Biomater 2016; 105:1938-1949. [DOI: 10.1002/jbm.b.33724] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/30/2016] [Accepted: 05/13/2016] [Indexed: 12/22/2022]
Affiliation(s)
- Ana Delia Pinzón-García
- Chemistry Department; Institute of Exact Sciences, Universidade Federal de Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Puebla Cassini-Vieira
- Department of Physiology and Biophysics; Institute of Biological Sciences, Universidade Federal de Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Cyntia Cabral Ribeiro
- Chemistry Department; Institute of Exact Sciences, Universidade Federal de Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | | | - Luciola Silva Barcelos
- Department of Physiology and Biophysics; Institute of Biological Sciences, Universidade Federal de Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Maria Esperanza Cortes
- Department of Restorative Dentistry, Faculty of Dentristry; Universidade Federal de Minas Gerais; Belo Horizonte Minas Gerais Brazil
| | - Ruben Dario Sinisterra
- Chemistry Department; Institute of Exact Sciences, Universidade Federal de Minas Gerais; Belo Horizonte Minas Gerais Brazil
| |
Collapse
|
4
|
Dallon JC, Evans EJ, Ehrlich HP. A mathematical model of collagen lattice contraction. J R Soc Interface 2015; 11:rsif.2014.0598. [PMID: 25142520 DOI: 10.1098/rsif.2014.0598] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Two mathematical models for fibroblast-collagen interaction are proposed which reproduce qualitative features of fibroblast-populated collagen lattice contraction. Both models are force based and model the cells as individual entities with discrete attachment sites; however, the collagen lattice is modelled differently in each model. In the collagen lattice model, the lattice is more interconnected and formed by triangulating nodes to form the fibrous structure. In the collagen fibre model, the nodes are not triangulated, are less interconnected, and the collagen fibres are modelled as a string of nodes. Both models suggest that the overall increase in stress of the lattice as it contracts is not the cause of the reduced rate of contraction, but that the reduced rate of contraction is due to inactivation of the fibroblasts.
Collapse
Affiliation(s)
- J C Dallon
- Department of Mathematics, Brigham Young University, Provo, UT 84602-6539, USA
| | - E J Evans
- Department of Mathematics, Brigham Young University, Provo, UT 84602-6539, USA
| | - H Paul Ehrlich
- Division of Plastic Surgery, Hershey Medical Center, Hershey, PA 17033, USA
| |
Collapse
|
5
|
Dallon JC, Scott M, Smith WV. A force based model of individual cell migration with discrete attachment sites and random switching terms. J Biomech Eng 2014; 135:71008. [PMID: 23722520 DOI: 10.1115/1.4023987] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Indexed: 11/08/2022]
Abstract
A force based model of cell migration is presented which gives new insight into the importance of the dynamics of cell binding to the substrate. The main features of the model are the focus on discrete attachment dynamics, the treatment of the cellular forces as springs, and an incorporation of the stochastic nature of the attachment sites. One goal of the model is to capture the effect of the random binding and unbinding of cell attachments on global cell motion. Simulations reveal one of the most important factor influencing cell speed is the duration of the attachment to the substrate. The model captures the correct velocity and force relationships for several cell types.
Collapse
Affiliation(s)
- J C Dallon
- Department of Mathematics, Brigham Young University, Provo, UT 84602, USA.
| | | | | |
Collapse
|
6
|
Cell speed is independent of force in a mathematical model of amoeboidal cell motion with random switching terms. Math Biosci 2013; 246:1-7. [DOI: 10.1016/j.mbs.2013.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 09/05/2013] [Accepted: 09/11/2013] [Indexed: 12/31/2022]
|
7
|
Leung LH, Naguib HE. Characterization of the viscoelastic properties of poly(ε-caprolactone)-hydroxyapatite microcomposite and nanocomposite scaffolds. POLYM ENG SCI 2012. [DOI: 10.1002/pen.23108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
|
8
|
Murphy KE, Hall CL, Maini PK, McCue SW, McElwain DLS. A Fibrocontractive Mechanochemical Model of Dermal Wound Closure Incorporating Realistic Growth Factor Kinetics. Bull Math Biol 2012; 74:1143-70. [DOI: 10.1007/s11538-011-9712-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 12/15/2011] [Indexed: 11/30/2022]
|
9
|
Gutierrez E, Groisman A. Measurements of elastic moduli of silicone gel substrates with a microfluidic device. PLoS One 2011; 6:e25534. [PMID: 21980487 PMCID: PMC3184124 DOI: 10.1371/journal.pone.0025534] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 09/07/2011] [Indexed: 11/19/2022] Open
Abstract
Thin layers of gels with mechanical properties mimicking animal tissues are widely used to study the rigidity sensing of adherent animal cells and to measure forces applied by cells to their substrate with traction force microscopy. The gels are usually based on polyacrylamide and their elastic modulus is measured with an atomic force microscope (AFM). Here we present a simple microfluidic device that generates high shear stresses in a laminar flow above a gel-coated substrate and apply the device to gels with elastic moduli in a range from 0.4 to 300 kPa that are all prepared by mixing two components of a transparent commercial silicone Sylgard 184. The elastic modulus is measured by tracking beads on the gel surface under a wide-field fluorescence microscope without any other specialized equipment. The measurements have small and simple to estimate errors and their results are confirmed by conventional tensile tests. A master curve is obtained relating the mixing ratios of the two components of Sylgard 184 with the resulting elastic moduli of the gels. The rigidity of the silicone gels is less susceptible to effects from drying, swelling, and aging than polyacrylamide gels and can be easily coated with fluorescent tracer particles and with molecules promoting cellular adhesion. This work can lead to broader use of silicone gels in the cell biology laboratory and to improved repeatability and accuracy of cell traction force microscopy and rigidity sensing experiments.
Collapse
Affiliation(s)
- Edgar Gutierrez
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
| | - Alex Groisman
- Department of Physics, University of California San Diego, La Jolla, California, United States of America
- * E-mail:
| |
Collapse
|
10
|
A two-compartment mechanochemical model of the roles of transforming growth factor and tissue tension in dermal wound healing. J Theor Biol 2011; 272:145-59. [DOI: 10.1016/j.jtbi.2010.12.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 12/06/2010] [Accepted: 12/08/2010] [Indexed: 12/30/2022]
|
11
|
Pohl H. Changes in the structure of collagen distribution in the skin caused by a manual technique. J Bodyw Mov Ther 2010; 14:27-34. [DOI: 10.1016/j.jbmt.2008.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 06/01/2008] [Accepted: 06/03/2008] [Indexed: 12/01/2022]
|
12
|
Saleem MA, Zavadil J, Bailly M, McGee K, Witherden IR, Pavenstadt H, Hsu H, Sanday J, Satchell SC, Lennon R, Ni L, Bottinger EP, Mundel P, Mathieson PW. The molecular and functional phenotype of glomerular podocytes reveals key features of contractile smooth muscle cells. Am J Physiol Renal Physiol 2008; 295:F959-70. [PMID: 18684887 PMCID: PMC2576149 DOI: 10.1152/ajprenal.00559.2007] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The glomerular podocyte is a highly specialized cell, with the ability to ultrafilter blood and support glomerular capillary pressures. However, little is known about either the genetic programs leading to this functionality or the final phenotype. We approached this question utilizing a human conditionally immortalized cell line, which differentiates from a proliferating epithelial phenotype to a differentiated form. We profiled gene expression during several time points during differentiation and grouped the regulated genes into major functional categories. A novel category of genes that was upregulated during differentiation was of smooth muscle-related molecules. We further examined the smooth muscle phenotype and showed that podocytes consistently express the differentiated smooth muscle markers smoothelin and calponin and the specific transcription factor myocardin, both in vitro and in vivo. The contractile contribution of the podocyte to the glomerular capillary is controversial. We demonstrated using two novel techniques that podocytes contract vigorously in vitro when differentiated and in real time were able to demonstrate that angiotensin II treatment decreases monolayer resistance, morphologically correlating with enhanced contractility. We conclude that the mature podocyte in vitro possesses functional apparatus of contractile smooth muscle cells, with potential implications for its in vivo ability to regulate glomerular dynamic and permeability characteristics.
Collapse
Affiliation(s)
- Moin A Saleem
- Academic and Children's Renal Unit, University of Bristol, Lifeline Bldg., Southmead Hospital, Bristol, BS10 5NB, United Kingdom.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Leung L, Chan C, Song J, Tam B, Naguib H. A Parametric Study on the Processing and Physical Characterization of PLGA 50/50 Bioscaffolds. J CELL PLAST 2008. [DOI: 10.1177/0021955x07084909] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The ability to control the characteristics of scaffolds is important such that scaffolds can be fine tuned for specific applications. In this study, the effects of processing parameters on cell morphology and mechanical properties of PLGA 50/50 bioscaffolds for tissue engineering applications were investigated. Specifically, the effects of salt particle sizes and salt-to-polymer mass ratios on the scaffold relative density, average pore size and density, open-cell porosity, and mechanical properties were examined. The PLGA samples were processed using a salt leaching technique in a batch-foaming setup. Experiments showed that pore size and density were dependent on the salt particle size used, and that as the salt-to-polymer mass ratio increased, the porosity increased while the relative density decreased. The results showed that by varying the salt parameters during fabrication, the scaffold characteristics and morphology can be controlled.
Collapse
Affiliation(s)
- Linus Leung
- University of Toronto, Department of Mechanical and Industrial Engineering, Department of Materials Science and Engineering 5 King's College Road, Toronto, Ontario, Canada M5S 3G8
| | - Christine Chan
- Department of Materials Science and Engineering University of Toronto 5 King's College Road, Toronto, Ontario, Canada M5S 3G8
| | - Janice Song
- Department of Materials Science and Engineering University of Toronto 5 King's College Road, Toronto, Ontario, Canada M5S 3G8
| | - Billy Tam
- Department of Materials Science and Engineering University of Toronto 5 King's College Road, Toronto, Ontario, Canada M5S 3G8
| | - Hani Naguib
- University of Toronto, Department of Mechanical and Industrial Engineering, Department of Materials Science and Engineering 5 King's College Road, Toronto, Ontario, Canada M5S 3G8, , Department of Materials Science and Engineering University of Toronto 5 King's College Road, Toronto, Ontario, Canada M5S 3G8
| |
Collapse
|
14
|
Leung L, Chan C, Baek S, Naguib H. Comparison of morphology and mechanical properties of PLGA bioscaffolds. Biomed Mater 2008; 3:025006. [PMID: 18458364 DOI: 10.1088/1748-6041/3/2/025006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In this study, bioscaffolds using poly(DL-lactide-co-glycolide) acid (PLGA) were fabricated and studied. The gas foaming/salt leaching technique in a batch foaming setup was employed, and the effects of material composition of PLGA on the morphology and mechanical properties using this process were investigated. Two material compositions of PLGA 50/50 and 85/15 were used, and characterization of scaffolds fabricated with these materials showed that a lower relative density can be achieved with an increasing poly(DL-lactide) acid (PDLLA) content; however, higher open-cell porosity was obtained with lower PDLLA content. Furthermore, the effect of PLGA composition on modulus of the scaffolds was minor.
Collapse
Affiliation(s)
- L Leung
- Department of Mechanical and Industrial Engineering, University of Toronto, 5 King's College Road, Toronto, Ontario, M5S 3G8, Canada
| | | | | | | |
Collapse
|
15
|
Choi JS, Leong KW, Yoo HS. In vivo wound healing of diabetic ulcers using electrospun nanofibers immobilized with human epidermal growth factor (EGF). Biomaterials 2008; 29:587-96. [DOI: 10.1016/j.biomaterials.2007.10.012] [Citation(s) in RCA: 399] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Accepted: 10/09/2007] [Indexed: 01/27/2023]
|
16
|
Guan L, Davies JE. Preparation and characterization of a highly macroporous biodegradable composite tissue engineering scaffold. J Biomed Mater Res A 2005; 71:480-7. [PMID: 15478140 DOI: 10.1002/jbm.a.30173] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
A unique composite scaffold for bone-tissue engineering applications has been prepared by combining biodegradable poly(lactide-co-glycolide) (PLGA) with bioresorbable calcium phosphate (CaP) cement particles through the process of particle fusion and phase separation/particle leaching. The scaffold is characterized by a highly interconnected macroporosity, with macropores of 0.8-1.8 mm and porosities ranging from 81% to 91%, and improved mechanical properties with respect to the polymer alone, producing excellent dimensional stability. The scaffold properties were controlled by adjusting the processing parameters, including PLGA molar mass and concentration, CaP/PLGA ratio, and porogen size. The differences in mechanical properties between dry, wet/room temperature, and wet/37 degrees C testing conditions, of which the latter are more relevant for materials to be employed in a biological milieu, were investigated. Thus, a scaffold made from PLGA IV 1.13, PLGA concentration 12.5%, and CaP/PLGA ratio 2:1 exhibited significantly different compressive strengths of 0.16 MPa and 0.04 MPa when tested under dry and wet/37 degrees C conditions, respectively. .
Collapse
Affiliation(s)
- Limin Guan
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, 4 Taddle Creek Road, Toronto, Ontario M5S 3G9, Canada
| | | |
Collapse
|
17
|
Abstract
Motile fibroblasts generate forces that can be expressed as cell migration or as traction, the drawing-in of extracellular matrix. Traction by cultured fibroblasts can induce a rapid concerted reorganization of collagen gel, creating a pattern of collagen alignment similar to that seen in tendons and ligaments. In such fibrous connective tissues, after pattern morphogenesis is complete, ongoing traction may be responsible for the maintenance of proper form and function. The molecules that generate and transmit forces have been catalogued; however, how these nanometer-scale molecules contribute to millimeter-scale patterns has not been directly tested. Here, we placed pairs of explants of human periodontal ligament fibroblasts in collagen gels, where ligament-like straps of anisotropic collagen formed on the axes between them. We scrutinized the traction apparatus using electron microscopy, video microscopy, and computer-based pattern analysis, augmented with pharmacologic inhibitors of cytoskeletal function. Patterning was marked by the co-alignment of collagen, fibroblasts, and their actin cytoskeletons, all parallel to the axis between explants. The pattern was diminished by depolymerizing actin filaments or by blocking myosin activity, but was accentuated by depolymerizing microtubules. The plasma membrane also seems to contribute to the traction force. These molecular components combine to exert a sub-maximal traction force on the matrix, suggesting that the force may be regulated to ensure tissue tensional homeostasis.
Collapse
Affiliation(s)
- Ravi K Sawhney
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | | |
Collapse
|
18
|
Jakab K, Neagu A, Mironov V, Markwald RR, Forgacs G. Engineering biological structures of prescribed shape using self-assembling multicellular systems. Proc Natl Acad Sci U S A 2004; 101:2864-9. [PMID: 14981244 PMCID: PMC365711 DOI: 10.1073/pnas.0400164101] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2003] [Indexed: 01/28/2023] Open
Abstract
Self-assembly is a fundamental process that drives structural organization in both inanimate and living systems. It is in the course of self-assembly of cells and tissues in early development that the organism and its parts eventually acquire their final shape. Even though developmental patterning through self-assembly is under strict genetic control it is clear that ultimately it is physical mechanisms that bring about the complex structures. Here we show, both experimentally and by using computer simulations, how tissue liquidity can be used to build tissue constructs of prescribed geometry in vitro. Spherical aggregates containing many thousands of cells, which form because of tissue liquidity, were implanted contiguously into biocompatible hydrogels in circular geometry. Depending on the properties of the gel, upon incubation, the aggregates either fused into a toroidal 3D structure or their constituent cells dispersed into the surrounding matrix. The model simulations, which reproduced the experimentally observed shapes, indicate that the control parameter of structure evolution is the aggregate-gel interfacial tension. The model-based analysis also revealed that the observed toroidal structure represents a metastable state of the cellular system, whose lifetime depends on the magnitude of cell-cell and cell-matrix interactions. Thus, these constructs can be made long-lived. We suggest that spherical aggregates composed of organ-specific cells may be used as "bio-ink" in the evolving technology of organ printing.
Collapse
Affiliation(s)
- Karoly Jakab
- Department of Physics, University of Missouri, Columbia, MO 65211, USA
| | | | | | | | | |
Collapse
|
19
|
Sawhney RK, Howard J. Slow local movements of collagen fibers by fibroblasts drive the rapid global self-organization of collagen gels. J Cell Biol 2002; 157:1083-91. [PMID: 12058022 PMCID: PMC2174051 DOI: 10.1083/jcb.200203069] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2002] [Revised: 04/25/2002] [Accepted: 04/30/2002] [Indexed: 11/22/2022] Open
Abstract
Aclassic model for tissue morphogenesis is the formation of ligament-like straps between explants of fibroblasts placed in collagen gels. The patterns arise from mechanical forces exerted by cells on their substrates (Harris et al., 1981). However, where do such straps come from, and how are slow local movements of cells transduced into dramatic long-distance redistributions of collagen? We embedded primary mouse skin and human periodontal ligament fibroblasts in collagen gels and measured the time course of patterning by using a novel computer algorithm to calculate anisotropy, and by tracking glass beads dispersed in the gel. As fibroblasts began to spread into their immediate environments, a coordinated rearrangement of collagen commenced throughout the gel, producing a strap on a time scale of minutes. Killing of cells afterwards resulted in a partial relaxation of the matrix strain. Surprisingly, relatively small movements of collagen molecules on the tensile axis between two pulling explants induced a much larger concomitant compression of the gel perpendicular to the axis, organizing and aligning fibers into a strap. We propose that this amplification is due to the geometry of the collagen matrix, and that analogous amplified movements may drive morphological changes in other biological meshes, both outside and inside the cell.
Collapse
Affiliation(s)
- Ravi K Sawhney
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | | |
Collapse
|
20
|
Wrobel LK, Fray TR, Molloy JE, Adams JJ, Armitage MP, Sparrow JC. Contractility of single human dermal myofibroblasts and fibroblasts. CELL MOTILITY AND THE CYTOSKELETON 2002; 52:82-90. [PMID: 12112150 DOI: 10.1002/cm.10034] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Human dermal myofibroblasts, characterised by the expression of alpha-smooth muscle actin, are part of the granulation tissue and implicated in the generation of contractile forces during normal wound healing and pathological contractures. We have compared the contractile properties of single human dermal fibroblasts and human dermal myofibroblasts by culturing them on flexible silicone elastomers. The flexibility of the silicone substratum permits the contractile forces exerted by the cells to be measured [Fray et al., 1998: Tissue Eng. 4:273-283], without changing their expression of alpha-smooth muscle actin. The mean contractile force produced by myofibroblasts (2.2 microN per cell) was not significantly different from that generated by fibroblasts (2.0 microN per cell) when cultured on a substrata with a low elastomer stiffness. Forces produced by fibroblasts were unaffected by increases in elastomer stiffness, but forces measured for myofibroblasts increased to a mean value of 4.1 microN/cell. This was associated with a higher proportion of myofibroblasts being able to produce wrinkles on elastomers of high stiffness compared to fibroblasts. We discuss the force measurements at the single cell level, for both fibroblast and myofibroblasts, in relation to the proposed role of myofibroblasts in wound healing and pathological contractures.
Collapse
Affiliation(s)
- Louise K Wrobel
- Department of Biology, University of York, York, United Kingdom
| | | | | | | | | | | |
Collapse
|
21
|
Hinz B, Celetta G, Tomasek JJ, Gabbiani G, Chaponnier C. Alpha-smooth muscle actin expression upregulates fibroblast contractile activity. Mol Biol Cell 2001; 12:2730-41. [PMID: 11553712 PMCID: PMC59708 DOI: 10.1091/mbc.12.9.2730] [Citation(s) in RCA: 966] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
To evaluate whether alpha-smooth muscle actin (alpha-SMA) plays a role in fibroblast contractility, we first compared the contractile activity of rat subcutaneous fibroblasts (SCFs), expressing low levels of alpha-SMA, with that of lung fibroblasts (LFs), expressing high levels of alpha-SMA, with the use of silicone substrates of different stiffness degrees. On medium stiffness substrates the percentage of cells producing wrinkles was similar to that of alpha-SMA-positive cells in each fibroblast population. On high stiffness substrates, wrinkle production was limited to a subpopulation of LFs very positive for alpha-SMA. In a second approach, we measured the isotonic contraction of SCF- and LF-populated attached collagen lattices. SCFs exhibited 41% diameter reduction compared with 63% by LFs. TGFbeta1 increased alpha-SMA expression and lattice contraction by SCFs to the levels of LFs; TGFbeta-antagonizing agents reduced alpha-SMA expression and lattice contraction by LFs to the level of SCFs. Finally, 3T3 fibroblasts transiently or permanently transfected with alpha-SMA cDNA exhibited a significantly higher lattice contraction compared with wild-type 3T3 fibroblasts or to fibroblasts transfected with alpha-cardiac and beta- or gamma-cytoplasmic actin. This took place in the absence of any change in smooth muscle or nonmuscle myosin heavy-chain expression. Our results indicate that an increased alpha-SMA expression is sufficient to enhance fibroblast contractile activity.
Collapse
Affiliation(s)
- B Hinz
- Department of Pathology, CMU, University of Geneva, 1211 Geneva 4, Switzerland
| | | | | | | | | |
Collapse
|