1
|
Valproic acid modulates collagen architecture in the postoperative conjunctival scar. J Mol Med (Berl) 2022; 100:947-961. [PMID: 35583819 DOI: 10.1007/s00109-021-02171-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 11/10/2021] [Accepted: 11/29/2021] [Indexed: 10/18/2022]
Abstract
Valproic acid (VPA), widely used for the treatment of neurological disorders, has anti-fibrotic activity by reducing collagen production in the postoperative conjunctiva. In this study, we investigated the capacity of VPA to modulate the postoperative collagen architecture. Histochemical examination revealed that VPA treatment was associated with the formation of thinner collagen fibers in the postoperative days 7 and 14 scars. At the micrometer scale, measurements by quantitative multiphoton microscopy indicated that VPA reduced mean collagen fiber thickness by 1.25-fold. At the nanometer scale, collagen fibril thickness and diameter measured by transmission electron microscopy were decreased by 1.08- and 1.20-fold, respectively. Moreover, delicate filamentous structures in random aggregates or closely associated with collagen fibrils were frequently observed in VPA-treated tissue. At the molecular level, VPA reduced Col1a1 but induced Matn2, Matn3, and Matn4 in the postoperative day 7 conjunctival tissue. Elevation of matrilin protein expression induced by VPA was sustained till at least postoperative day 14. In primary conjunctival fibroblasts, Matn2 expression was resistant to both VPA and TGF-β2, Matn3 was sensitive to both VPA and TGF-β2 individually and synergistically, while Matn4 was modulable by VPA but not TGF-β2. MATN2, MATN3, and MATN4 localized in close association with COL1A1 in the postoperative conjunctiva. These data indicate that VPA has the capacity to reduce collagen fiber thickness and potentially collagen assembly, in association with matrilin upregulation. These properties suggest potential VPA application for the prevention of fibrotic progression in the postoperative conjunctiva. KEY MESSAGES: VPA reduces collagen fiber and fibril thickness in the postoperative scar. VPA disrupts collagen fiber assembly in conjunctival wound healing. VPA induces MATN2, MATN3, and MATN4 in the postoperative scar.
Collapse
|
2
|
Moghaddam AO, Lin Z, Sivaguru M, Phillips H, McFarlin BL, Toussaint KC, Johnson AJW. Heterogeneous microstructural changes of the cervix influence cervical funneling. Acta Biomater 2022; 140:434-445. [PMID: 34958969 PMCID: PMC8828692 DOI: 10.1016/j.actbio.2021.12.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/03/2021] [Accepted: 12/21/2021] [Indexed: 12/31/2022]
Abstract
The cervix acts as a dynamic barrier between the uterus and vagina, retaining the fetus during pregnancy and allowing birth at term. Critical to this function, the physical properties of the cervix change, or remodel, but abnormal remodeling can lead to preterm birth (PTB). Although cervical remodeling has been studied, the complex 3D cervical microstructure has not been well-characterized. In this complex, dynamic, and heterogeneous tissue microenvironment, the microstructural changes are likely also heterogeneous. Using quantitative, 3D, second-harmonic generation microscopy, we demonstrate that rat cervical remodeling during pregnancy is not uniform across the cervix; the collagen fibers orient progressively more perpendicular to the cervical canals in the inner cervical zone, but do not reorient in other regions. Furthermore, regions that are microstructurally distinct early in pregnancy become more similar as pregnancy progresses. We use a finite element simulation to show that heterogeneous regional changes influence cervical funneling, an important marker of increased risk for PTB; the internal cervical os shows ∼6.5x larger radial displacement when fibers in the inner cervical zone are parallel to the cervical canals compared to when fibers are perpendicular to the canals. Our results provide new insights into the microstructural and tissue-level cervical changes that have been correlated with PTB and motivate further clinical studies exploring the origins of cervical funneling. STATEMENT OF SIGNIFICANCE: Cervical funneling, or dilation of the internal cervical os, is highly associated with increased risk of preterm birth. This study explores the 3D microstructural changes of the rat cervix during pregnancy and illustrates how these changes influence cervical funneling, assuming similar evolution in rats and humans. Quantitative imaging showed that microstructural remodeling during pregnancy is nonuniform across cervical regions and that initially distinct regions become more similar. We report, for the first time, that remodeling of the inner cervical zone can influence the dilation of the internal cervical os and allow the cervix to stay closed despite increased intrauterine pressure. Our results suggest a possible relationship between the microstructural changes of this zone and cervical funneling, motivating further clinical investigations.
Collapse
Affiliation(s)
- A. Ostadi Moghaddam
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
| | - Z. Lin
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - M. Sivaguru
- Flow Cytometry and Microscopy to Omics, Roy J. Carver Biotechnology Center, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA
| | - H. Phillips
- Department of Veterinary Clinical Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - B. L. McFarlin
- Department of Women, Children and Family Health Science, University of Illinois College of Nursing, Chicago, IL 60612, USA
| | - K. C. Toussaint
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - A. J. Wagoner Johnson
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA,Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Champaign, IL 61820, USA,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA,Corresponding author at: 2101A Mechanical Engineering Laboratory MC-244, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801, United States.
| |
Collapse
|
3
|
Collagen Bioinks for Bioprinting: A Systematic Review of Hydrogel Properties, Bioprinting Parameters, Protocols, and Bioprinted Structure Characteristics. Biomedicines 2021; 9:biomedicines9091137. [PMID: 34572322 PMCID: PMC8468019 DOI: 10.3390/biomedicines9091137] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/05/2021] [Accepted: 08/27/2021] [Indexed: 01/01/2023] Open
Abstract
Bioprinting is a modern tool suitable for creating cell scaffolds and tissue or organ carriers from polymers that mimic tissue properties and create a natural environment for cell development. A wide range of polymers, both natural and synthetic, are used, including extracellular matrix and collagen-based polymers. Bioprinting technologies, based on syringe deposition or laser technologies, are optimal tools for creating precise constructs precisely from the combination of collagen hydrogel and cells. This review describes the different stages of bioprinting, from the extraction of collagen hydrogels and bioink preparation, over the parameters of the printing itself, to the final testing of the constructs. This study mainly focuses on the use of physically crosslinked high-concentrated collagen hydrogels, which represents the optimal way to create a biocompatible 3D construct with sufficient stiffness. The cell viability in these gels is mainly influenced by the composition of the bioink and the parameters of the bioprinting process itself (temperature, pressure, cell density, etc.). In addition, a detailed table is included that lists the bioprinting parameters and composition of custom bioinks from current studies focusing on printing collagen gels without the addition of other polymers. Last but not least, our work also tries to refute the often-mentioned fact that highly concentrated collagen hydrogel is not suitable for 3D bioprinting and cell growth and development.
Collapse
|
4
|
Wahlsten A, Rütsche D, Nanni M, Giampietro C, Biedermann T, Reichmann E, Mazza E. Mechanical stimulation induces rapid fibroblast proliferation and accelerates the early maturation of human skin substitutes. Biomaterials 2021; 273:120779. [PMID: 33932701 DOI: 10.1016/j.biomaterials.2021.120779] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 02/28/2021] [Accepted: 03/20/2021] [Indexed: 11/19/2022]
Abstract
The clinical treatment of large, full-thickness skin injuries with tissue-engineered autologous dermo-epidermal skin substitutes is an emerging alternative to split-thickness skin grafting. However, their production requires about one month of in vitro cell and tissue culture, which is a significant drawback for the treatment of patients with severe skin defects. With the aim to reduce the production time, we developed a new dynamic bioreactor setup that applies cyclic biaxial tension to collagen hydrogels for skin tissue engineering. By reliably controlling the time history of mechanical loading, the dynamic culturing results in a three-fold increase in collagen hydrogel stiffness and stimulates the embedded fibroblasts to enter the cell cycle. As a result, the number of fibroblasts is increased by 75% compared to under corresponding static culturing. Enhanced fibroblast proliferation promotes expression of dermal extracellular matrix proteins, keratinocyte proliferation, and the early establishment of the epidermis. The time required for early tissue maturation can therefore be reduced by one week. Analysis of the separate effects of cyclic loading, matrix stiffening, and interstitial fluid flow indicates that cyclic deformation is the dominant biophysical factor determining fibroblast proliferation, while tissue stiffening plays a lesser role. Local differences in the direction of deformation (in-plane equibiaxial vs. uniaxial strain) influence fibroblast orientation but not proliferation, nor the resulting tissue properties. Importantly, dynamic culturing does not activate fibroblast differentiation into myofibroblasts. The present work demonstrates that control of mechanobiological cues can be very effective in driving cell response toward a shorter production time for human skin substitutes.
Collapse
Affiliation(s)
- Adam Wahlsten
- Institute for Mechanical Systems, Department of Mechanical and Process Engineering, ETH Zurich, Leonhardstrasse 21, 8092 Zurich, Switzerland
| | - Dominic Rütsche
- Tissue Biology Research Unit, Department of Surgery, University Children's Hospital Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland; Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Monica Nanni
- Institute for Mechanical Systems, Department of Mechanical and Process Engineering, ETH Zurich, Leonhardstrasse 21, 8092 Zurich, Switzerland; Tissue Biology Research Unit, Department of Surgery, University Children's Hospital Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland; Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Costanza Giampietro
- Institute for Mechanical Systems, Department of Mechanical and Process Engineering, ETH Zurich, Leonhardstrasse 21, 8092 Zurich, Switzerland; Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
| | - Thomas Biedermann
- Tissue Biology Research Unit, Department of Surgery, University Children's Hospital Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland; Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Ernst Reichmann
- Tissue Biology Research Unit, Department of Surgery, University Children's Hospital Zurich, Wagistrasse 12, 8952 Schlieren, Switzerland; Children's Research Center, University Children's Hospital Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland.
| | - Edoardo Mazza
- Institute for Mechanical Systems, Department of Mechanical and Process Engineering, ETH Zurich, Leonhardstrasse 21, 8092 Zurich, Switzerland; Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland.
| |
Collapse
|
5
|
Woessner AE, Jones JD, Witt NJ, Sander EA, Quinn KP. Three-Dimensional Quantification of Collagen Microstructure During Tensile Mechanical Loading of Skin. Front Bioeng Biotechnol 2021; 9:642866. [PMID: 33748088 PMCID: PMC7966723 DOI: 10.3389/fbioe.2021.642866] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 02/11/2021] [Indexed: 11/22/2022] Open
Abstract
Skin is a heterogeneous tissue that can undergo substantial structural and functional changes with age, disease, or following injury. Understanding how these changes impact the mechanical properties of skin requires three-dimensional (3D) quantification of the tissue microstructure and its kinematics. The goal of this study was to quantify these structure-function relationships via second harmonic generation (SHG) microscopy of mouse skin under tensile mechanical loading. Tissue deformation at the macro- and micro-scale was quantified, and a substantial decrease in tissue volume and a large Poisson’s ratio was detected with stretch, indicating the skin differs substantially from the hyperelastic material models historically used to explain its behavior. Additionally, the relative amount of measured strain did not significantly change between length scales, suggesting that the collagen fiber network is uniformly distributing applied strains. Analysis of undeformed collagen fiber organization and volume fraction revealed a length scale dependency for both metrics. 3D analysis of SHG volumes also showed that collagen fiber alignment increased in the direction of stretch, but fiber volume fraction did not change. Interestingly, 3D fiber kinematics was found to have a non-affine relationship with tissue deformation, and an affine transformation of the micro-scale fiber network overestimates the amount of fiber realignment. This result, along with the other outcomes, highlights the importance of accurate, scale-matched 3D experimental measurements when developing multi-scale models of skin mechanical function.
Collapse
Affiliation(s)
- Alan E Woessner
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, United States
| | - Jake D Jones
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, United States
| | - Nathan J Witt
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
| | - Edward A Sander
- Department of Biomedical Engineering, University of Iowa, Iowa City, IA, United States
| | - Kyle P Quinn
- Department of Biomedical Engineering, University of Arkansas, Fayetteville, AR, United States
| |
Collapse
|
6
|
Benboujja F, Hartnick C. Quantitative evaluation of the human vocal fold extracellular matrix using multiphoton microscopy and optical coherence tomography. Sci Rep 2021; 11:2440. [PMID: 33510352 PMCID: PMC7844040 DOI: 10.1038/s41598-021-82157-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/11/2021] [Indexed: 02/07/2023] Open
Abstract
Identifying distinct normal extracellular matrix (ECM) features from pathology is of the upmost clinical importance for laryngeal diagnostics and therapy. Despite remarkable histological contributions, our understanding of the vocal fold (VF) physiology remains murky. The emerging field of non-invasive 3D optical imaging may be well-suited to unravel the complexity of the VF microanatomy. This study focused on characterizing the entire VF ECM in length and depth with optical imaging. A quantitative morphometric evaluation of the human vocal fold lamina propria using two-photon excitation fluorescence (TPEF), second harmonic generation (SHG), and optical coherence tomography (OCT) was investigated. Fibrillar morphological features, such as fiber diameter, orientation, anisotropy, waviness and second-order statistics features were evaluated and compared according to their spatial distribution. The evidence acquired in this study suggests that the VF ECM is not a strict discrete three-layer structure as traditionally described but instead a continuous assembly of different fibrillar arrangement anchored by predominant collagen transitions zones. We demonstrated that the ECM composition is distinct and markedly thinned in the anterior one-third of itself, which may play a role in the development of some laryngeal diseases. We further examined and extracted the relationship between OCT and multiphoton imaging, promoting correspondences that could lead to accurate 3D mapping of the VF architecture in real-time during phonosurgeries. As miniaturization of optical probes is consistently improving, a clinical translation of OCT imaging and multiphoton imaging, with valuable qualitative and quantitative features, may have significant implications for treating voice disorders.
Collapse
Affiliation(s)
- Fouzi Benboujja
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA
| | - Christopher Hartnick
- Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles Street, Boston, MA, 02114, USA.
| |
Collapse
|
7
|
Walimbe T, Panitch A. Best of Both Hydrogel Worlds: Harnessing Bioactivity and Tunability by Incorporating Glycosaminoglycans in Collagen Hydrogels. Bioengineering (Basel) 2020; 7:E156. [PMID: 33276506 PMCID: PMC7711789 DOI: 10.3390/bioengineering7040156] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 11/26/2020] [Accepted: 11/30/2020] [Indexed: 01/13/2023] Open
Abstract
Collagen, the most abundant protein in mammals, has garnered the interest of scientists for over 50 years. Its ubiquitous presence in all body tissues combined with its excellent biocompatibility has led scientists to study its potential as a biomaterial for a wide variety of biomedical applications with a high degree of success and widespread clinical approval. More recently, in order to increase their tunability and applicability, collagen hydrogels have frequently been co-polymerized with other natural and synthetic polymers. Of special significance is the use of bioactive glycosaminoglycans-the carbohydrate-rich polymers of the ECM responsible for regulating tissue homeostasis and cell signaling. This review covers the recent advances in the development of collagen-based hydrogels and collagen-glycosaminoglycan blend hydrogels for biomedical research. We discuss the formulations and shortcomings of using collagen in isolation, and the advantages of incorporating glycosaminoglycans (GAGs) in the hydrogels. We further elaborate on modifications used on these biopolymers for tunability and discuss tissue specific applications. The information presented herein will demonstrate the versatility and highly translational value of using collagen blended with GAGs as hydrogels for biomedical engineering applications.
Collapse
Affiliation(s)
- Tanaya Walimbe
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA;
| | - Alyssa Panitch
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA;
- Department of Surgery, University of California Davis Health, Sacramento, CA 95817, USA
| |
Collapse
|
8
|
Zhang Y, Huang Z, Dong S, Liu Z, Liu Y, Tang L, Cheng T, Zhou X. Evaluation of Cell's Passability in the ECM Network. Biophys J 2020; 119:1056-1064. [PMID: 32891186 DOI: 10.1016/j.bpj.2020.07.032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/17/2020] [Accepted: 07/27/2020] [Indexed: 11/28/2022] Open
Abstract
The microstructure of the extracellular matrix (ECM) plays a key role in affecting cell migration, especially nonproteolytic migration. It is difficult, however, to measure some properties of the ECM, such as stiffness and the passability for cell migration. On the basis of a network model of collagen fiber in the ECM, which has been well applied to simulate mechanical behaviors such as the stress-strain relationship, damage, and failure, we proposed a series of methods to study the microstructural properties containing pore size and pore stiffness and to search for the possible migration paths for cells. Finally, with a given criterion, we quantitatively evaluated the passability of the ECM network for cell migration. The fiber network model with a microstructure and the analysis method presented in this study further our understanding of and ability to evaluate the properties of an ECM network.
Collapse
Affiliation(s)
- Yongrou Zhang
- Guangdong Key Laboratory of Modern Control Technology, Guangdong Institute of Intelligent Manufacturing, Guangzhou, Guangdong, China; School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, Guangdong, China
| | - Zetao Huang
- School of Computer Science and Engineering, South China University of Technology, Guangzhou, Guangdong, China
| | - Shoubin Dong
- School of Computer Science and Engineering, South China University of Technology, Guangzhou, Guangdong, China
| | - Zejia Liu
- School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, Guangdong, China.
| | - Yiping Liu
- School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, Guangdong, China
| | - Liqun Tang
- School of Civil Engineering and Transportation, South China University of Technology, Guangzhou, Guangdong, China; State Key Laboratory of Subtropical Building Science, South China University of Technology, Guangzhou, Guangdong, China
| | - Taobo Cheng
- Guangdong Key Laboratory of Modern Control Technology, Guangdong Institute of Intelligent Manufacturing, Guangzhou, Guangdong, China
| | - Xuefeng Zhou
- Guangdong Key Laboratory of Modern Control Technology, Guangdong Institute of Intelligent Manufacturing, Guangzhou, Guangdong, China.
| |
Collapse
|
9
|
Sohutskay DO, Buno KP, Tholpady SS, Nier SJ, Voytik-Harbin SL. Design and biofabrication of dermal regeneration scaffolds: role of oligomeric collagen fibril density and architecture. Regen Med 2020; 15:1295-1312. [PMID: 32228274 DOI: 10.2217/rme-2019-0084] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Aim: To evaluate dermal regeneration scaffolds custom-fabricated from fibril-forming oligomeric collagen where the total content and spatial gradient of collagen fibrils was specified. Materials & methods: Microstructural and mechanical features were verified by electron microscopy and tensile testing. The ability of dermal scaffolds to induce regeneration of rat full-thickness skin wounds was determined and compared with no fill control, autograft skin and a commercial collagen dressing. Results: Increasing fibril content of oligomer scaffolds inhibited wound contraction and decreased myofibroblast marker expression. Cellular and vascular infiltration of scaffolds over the 14-day period varied with the graded density and orientation of fibrils. Conclusion: Fibril content, spatial gradient and orientation are important collagen scaffold design considerations for promoting vascularization and dermal regeneration while reducing wound contraction.
Collapse
Affiliation(s)
- David O Sohutskay
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.,Medical Scientist Training Program, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Kevin P Buno
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Sunil S Tholpady
- Division of Plastic Surgery, Department of Surgery, Indiana University, IN 46202, USA.,Division of Plastic Surgery, Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, IN 46202, USA
| | - Samantha J Nier
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - Sherry L Voytik-Harbin
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47907, USA.,Department of Basic Medical Sciences, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
10
|
Punter MTJJM, Vos BE, Mulder BM, Koenderink GH. Poroelasticity of (bio)polymer networks during compression: theory and experiment. SOFT MATTER 2020; 16:1298-1305. [PMID: 31922166 DOI: 10.1039/c9sm01973a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Soft living tissues like cartilage can be considered as biphasic materials comprising a fibrous complex biopolymer network and a viscous background liquid. Here, we show by a combination of experiment and theoretical analysis that both the hydraulic permeability and the elastic properties of (bio)polymer networks can be determined with simple ramp compression experiments in a commercial rheometer. In our approximate closed-form solution of the poroelastic equations of motion, we find the normal force response during compression as a combination of network stress and fluid pressure. Choosing fibrin as a biopolymer model system with controllable pore size, measurements of the full time-dependent normal force during compression are found to be in excellent agreement with the theoretical calculations. The inferred elastic response of large-pore (μm) fibrin networks depends on the strain rate, suggesting a strong interplay between network elasticity and fluid flow. Phenomenologically extending the calculated normal force into the regime of nonlinear elasticity, we find strain-stiffening of small-pore (sub-μm) fibrin networks to occur at an onset average tangential stress at the gel-plate interface that depends on the polymer concentration in a power-law fashion. The inferred permeability of small-pore fibrin networks scales approximately inverse squared with the fibrin concentration, implying with a microscopic cubic lattice model that the number of protofibrils per fibrin fiber cross-section decreases with protein concentration. Our theoretical model provides a new method to obtain the hydraulic permeability and the elastic properties of biopolymer networks and hydrogels with simple compression experiments, and paves the way to study the relation between fluid flow and elasticity in biopolymer networks during dynamical compression.
Collapse
Affiliation(s)
- Melle T J J M Punter
- AMOLF, Theory of Biomolecular Matter, Science Park 104, 1098XG Amsterdam, The Netherlands.
| | | | | | | |
Collapse
|
11
|
Shivers JL, Arzash S, MacKintosh FC. Nonlinear Poisson Effect Governed by a Mechanical Critical Transition. PHYSICAL REVIEW LETTERS 2020; 124:038002. [PMID: 32031850 DOI: 10.1103/physrevlett.124.038002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Indexed: 06/10/2023]
Abstract
Under extensional strain, fiber networks can exhibit an anomalously large and nonlinear Poisson effect accompanied by a dramatic transverse contraction and volume reduction for applied strains as small as a few percent. We demonstrate that this phenomenon is controlled by a collective mechanical phase transition that occurs at a critical uniaxial strain that depends on network connectivity. This transition is punctuated by an anomalous peak in the apparent Poisson's ratio and other critical signatures such as diverging nonaffine strain fluctuations.
Collapse
Affiliation(s)
- Jordan L Shivers
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77030, USA
| | - Sadjad Arzash
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77030, USA
| | - F C MacKintosh
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77030, USA
- Departments of Chemistry and Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| |
Collapse
|
12
|
Ferruzzi J, Zhang Y, Roblyer D, Zaman MH. Multi-scale Mechanics of Collagen Networks: Biomechanical Basis of Matrix Remodeling in Cancer. MULTI-SCALE EXTRACELLULAR MATRIX MECHANICS AND MECHANOBIOLOGY 2020. [DOI: 10.1007/978-3-030-20182-1_11] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
|
13
|
Multiscale composite model of fiber-reinforced tissues with direct representation of sub-tissue properties. Biomech Model Mechanobiol 2019; 19:745-759. [PMID: 31686304 PMCID: PMC7105449 DOI: 10.1007/s10237-019-01246-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Accepted: 10/25/2019] [Indexed: 01/28/2023]
Abstract
In many fiber-reinforced tissues, collagen fibers are embedded within a glycosaminoglycan-rich extrafibrillar matrix. Knowledge of the structure-function relationship between the sub-tissue properties and bulk tissue mechanics is important for understanding tissue failure mechanics and developing biological repair strategies. Difficulties in directly measuring sub-tissue properties led to a growing interest in employing finite element modeling approaches. However, most models are homogeneous and are therefore not sufficient for investigating multiscale tissue mechanics, such as stress distributions between sub-tissue structures. To address this limitation, we developed a structure-based model informed by the native annulus fibrosus structure, where fibers and the matrix were described as distinct materials occupying separate volumes. A multiscale framework was applied such that the model was calibrated at the sub-tissue scale using single-lamellar uniaxial mechanical test data, while validated at the bulk scale by predicting tissue multiaxial mechanics for uniaxial tension, biaxial tension, and simple shear (13 cases). Structure-based model validation results were compared to experimental observations and homogeneous models. While homogeneous models only accurately predicted bulk tissue mechanics for one case, structure-based models accurately predicted bulk tissue mechanics for 12 of 13 cases, demonstrating accuracy and robustness. Additionally, six of eight structure-based model parameters were directly linked to tissue physical properties, further broadening its future applicability. In conclusion, the structure-based model provides a powerful multiscale modeling approach for simultaneously investigating the structure-function relationship at the sub-tissue and bulk tissue scale, which is important for studying multiscale tissue mechanics with degeneration, disease, or injury.
Collapse
|
14
|
Fiber alignment drives changes in architectural and mechanical features in collagen matrices. PLoS One 2019; 14:e0216537. [PMID: 31091287 PMCID: PMC6519824 DOI: 10.1371/journal.pone.0216537] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2018] [Accepted: 04/23/2019] [Indexed: 11/19/2022] Open
Abstract
Aligned collagen architecture is a characteristic feature of the tumor extracellular matrix (ECM) and has been shown to facilitate cancer metastasis using 3D in vitro models. Additional features of the ECM, such as pore size and stiffness, have also been shown to influence cellular behavior and are implicated in cancer progression. While there are several methods to produce aligned matrices to study the effect on cell behavior in vitro, it is unclear how the alignment itself may alter these other important features of the matrix. In this study, we have generated aligned collagen matrices and characterized their pore sizes and mechanical properties at the micro- and macro-scale. Our results indicate that collagen alignment can alter pore-size of matrices depending on the polymerization temperature of the collagen. Furthermore, alignment does not affect the macro-scale stiffness but alters the micro-scale stiffness in a temperature independent manner. Overall, these results describe the manifestation of confounding variables that arise due to alignment and the importance of fully characterizing biomaterials at both micro- and macro-scales.
Collapse
|
15
|
Ban E, Wang H, Franklin JM, Liphardt JT, Janmey PA, Shenoy VB. Strong triaxial coupling and anomalous Poisson effect in collagen networks. Proc Natl Acad Sci U S A 2019; 116:6790-6799. [PMID: 30894480 PMCID: PMC6452734 DOI: 10.1073/pnas.1815659116] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
While cells within tissues generate and sense 3D states of strain, the current understanding of the mechanics of fibrous extracellular matrices (ECMs) stems mainly from uniaxial, biaxial, and shear tests. Here, we demonstrate that the multiaxial deformations of fiber networks in 3D cannot be inferred solely based on these tests. The interdependence of the three principal strains gives rise to anomalous ratios of biaxial to uniaxial stiffness between 8 and 9 and apparent Poisson's ratios larger than 1. These observations are explained using a microstructural network model and a coarse-grained constitutive framework that predicts the network Poisson effect and stress-strain responses in uniaxial, biaxial, and triaxial modes of deformation as a function of the microstructural properties of the network, including fiber mechanics and pore size of the network. Using this theoretical approach, we found that accounting for the Poisson effect leads to a 100-fold increase in the perceived elastic stiffness of thin collagen samples in extension tests, reconciling the seemingly disparate measurements of the stiffness of collagen networks using different methods. We applied our framework to study the formation of fiber tracts induced by cellular forces. In vitro experiments with low-density networks showed that the anomalous Poisson effect facilitates higher densification of fibrous tracts, associated with the invasion of cancerous acinar cells. The approach developed here can be used to model the evolving mechanics of ECM during cancer invasion and fibrosis.
Collapse
Affiliation(s)
- Ehsan Ban
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104
| | - Hailong Wang
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104
- Department of Modern Mechanics, Chinese Academy of Sciences Key Laboratory of Mechanical Behavior and Design of Materials, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - J Matthew Franklin
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305
| | - Jan T Liphardt
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305
| | - Paul A Janmey
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA 19104
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104
| | - Vivek B Shenoy
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA 19104;
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104
- Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104
| |
Collapse
|
16
|
Li H, Mattson JM, Zhang Y. Integrating structural heterogeneity, fiber orientation, and recruitment in multiscale ECM mechanics. J Mech Behav Biomed Mater 2019; 92:1-10. [PMID: 30654215 PMCID: PMC6387859 DOI: 10.1016/j.jmbbm.2018.12.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 11/26/2018] [Accepted: 12/18/2018] [Indexed: 01/06/2023]
Abstract
Extracellular matrix (ECM) plays critical roles in establishing tissue structure-function relationships and controlling cell fate. However, the mechanisms by which ECM mechanics influence cell and tissue behavior remain to be elucidated since the events associated with this process span length scales from the tissue to molecular level. Entirely new methods are needed in order to better understand the multiscale mechanics of ECM. In this study, a multiscale experimental approach was established by integrating Optical Magnetic Twisting Cytometry (OMTC) with a biaxial tensile tester to study the microscopic (local) ECM mechanical properties under controlled tissue-level (global) loading. Adventitial layer of porcine thoracic artery was used as a collagen-based ECM. Multiphoton microscopy imaging was performed to capture the changes in ECM fiber structure during biaxial deformation. As visualized from multiphoton microscopy images, biaxial stretch induces gradual fiber straightening and the fiber families become evident at higher stretch levels. The OMTC measurements show that the local apparent storage and loss modulus increases with the global biaxial stretch, however there exists a complex interplay among local ECM mechanical properties, ECM structural heterogeneity, and fiber distribution and engagement. The phase lag does not change significantly with global biaxial stretch. Our results also show a much faster increase in global tissue tangent modulus compared to the local apparent complex modulus with biaxial stretch, indicating the scale dependency of ECM mechanics.
Collapse
Affiliation(s)
- Haiyue Li
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Jeffrey M Mattson
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA
| | - Yanhang Zhang
- Department of Mechanical Engineering, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
| |
Collapse
|
17
|
Devine EE, Liu Y, Keikhosravi A, Eliceiri KW, Jiang JJ. Quantitative second harmonic generation imaging of leporine, canine, and porcine vocal fold collagen. Laryngoscope 2019; 129:2549-2556. [PMID: 30628080 DOI: 10.1002/lary.27782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 11/12/2018] [Accepted: 12/10/2018] [Indexed: 11/09/2022]
Abstract
OBJECTIVES/HYPOTHESIS Vocal fold collagen composition is an important determinant of material properties and mucosal wave propagation. Collagen alignment and straightness are quantitatively characterized by second harmonic generation (SHG) imaging. We examined leporine, canined and porcine vocal folds showing collagen composition variation that is species, location, and strain specific. STUDY DESIGN Animal model. METHODS Leporine (n = 5), canine (n = 5), and porcine (n = 5) larynges were harvested and fixed in situ. Samples were transversely sectioned, and SHG images were collected for two inferior-superior sections along five anterior-posterior locations. Additional porcine samples were fixed and imaged under tensile strain (0%, 5%, 10%, 15%, 20%, n = 5 per group). Two-way repeated measures (RM) analysis of variance (ANOVA) tested for section and location differences in each species. Multiway RM-ANOVA tested for section, location, and strain differences in porcine samples. RESULTS Alignment and straightness were higher inferiorly in the porcine (P = .0047, P = .002) and canine (P = .0011, P < .001) vocal folds, but not in leporine samples (P = .67652, P = .4831). There were significant interactions between elongation and superior-inferior section for both alignment (P = .0047) and straightness (P = .0371). CONCLUSIONS Our results correspond well to findings in the literature that the inferior vocal fold lip is stiffer in porcine and canine larynges. The absence of a collagen gradient in the leporine vocal fold is notable because rabbits are less vocal animals, indicating the collagen gradient may be a result of voice use and an important consideration in model selection when extracellular matrix is of interest. Strain results were also consistent with the role of collagen in strain stiffening behavior of vocal fold tissue. LEVEL OF EVIDENCE NA Laryngoscope, 129:2549-2556, 2019.
Collapse
Affiliation(s)
- Erin E Devine
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Yuming Liu
- Department of Biomedical Engineering, Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Adib Keikhosravi
- Department of Biomedical Engineering, Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Kevin W Eliceiri
- Department of Biomedical Engineering, Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| | - Jack J Jiang
- Department of Surgery, Division of Otolaryngology-Head and Neck Surgery, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, Wisconsin, U.S.A
| |
Collapse
|
18
|
Reid JA, Mollica PA, Bruno RD, Sachs PC. Consistent and reproducible cultures of large-scale 3D mammary epithelial structures using an accessible bioprinting platform. Breast Cancer Res 2018; 20:122. [PMID: 30305139 PMCID: PMC6180647 DOI: 10.1186/s13058-018-1045-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 08/24/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Standard three-dimensional (3D) in vitro culture techniques, such as those used for mammary epithelial cells, rely on random distribution of cells within hydrogels. Although these systems offer advantages over traditional 2D models, limitations persist owing to the lack of control over cellular placement within the hydrogel. This results in experimental inconsistencies and random organoid morphology. Robust, high-throughput experimentation requires greater standardization of 3D epithelial culture techniques. METHODS Here, we detail the use of a 3D bioprinting platform as an investigative tool to control the 3D formation of organoids through the "self-assembly" of human mammary epithelial cells. Experimental bioprinting procedures were optimized to enable the formation of controlled arrays of individual mammary organoids. We define the distance and cell number parameters necessary to print individual organoids that do not interact between print locations as well as those required to generate large contiguous organoids connected through multiple print locations. RESULTS We demonstrate that as few as 10 cells can be used to form 3D mammary structures in a single print and that prints up to 500 μm apart can fuse to form single large structures. Using these fusion parameters, we demonstrate that both linear and non-linear (contiguous circles) can be generated with sizes of 3 mm in length/diameter. We confirm that cells from individual prints interact to form structures with a contiguous lumen. Finally, we demonstrate that organoids can be printed into human collagen hydrogels, allowing for all-human 3D culture systems. CONCLUSIONS Our platform is adaptable to different culturing protocols and is superior to traditional random 3D culture techniques in efficiency, reproducibility, and scalability. Importantly, owing to the low-cost accessibility and computer numerical control-driven platform of our 3D bioprinter, we have the ability to disseminate our experiments with absolute precision to interested laboratories.
Collapse
Affiliation(s)
- John A Reid
- Biomedical Engineering Institute, College of Engineering, Old Dominion University, 5115 Hampton Blvd, Norfolk, VA, 23529, USA
| | - Peter A Mollica
- School of Medical Diagnostic & Translational Sciences, College of Health Sciences, Old Dominion University, 5115 Hampton Blvd, Norfolk, VA, 23529, USA
| | - Robert D Bruno
- School of Medical Diagnostic & Translational Sciences, College of Health Sciences, Old Dominion University, 5115 Hampton Blvd, Norfolk, VA, 23529, USA.
| | - Patrick C Sachs
- School of Medical Diagnostic & Translational Sciences, College of Health Sciences, Old Dominion University, 5115 Hampton Blvd, Norfolk, VA, 23529, USA.
| |
Collapse
|
19
|
Ozcelikkale A, Dutton JC, Grinnell F, Han B. Effects of dynamic matrix remodelling on en masse migration of fibroblasts on collagen matrices. J R Soc Interface 2018; 14:rsif.2017.0287. [PMID: 28978745 DOI: 10.1098/rsif.2017.0287] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 09/12/2017] [Indexed: 12/19/2022] Open
Abstract
Fibroblast migration plays a key role during various physiological and pathological processes. Although migration of individual fibroblasts has been well studied, migration in vivo often involves simultaneous locomotion of fibroblasts sited in close proximity, so-called 'en masse migration', during which intensive cell-cell interactions occur. This study aims to understand the effects of matrix mechanical environments on the cell-matrix and cell-cell interactions during en masse migration of fibroblasts on collagen matrices. Specifically, we hypothesized that a group of migrating cells can significantly deform the matrix, whose mechanical microenvironment dramatically changes compared with the undeformed state, and the alteration of the matrix microenvironment reciprocally affects cell migration. This hypothesis was tested by time-resolved measurements of cell and extracellular matrix movement during en masse migration on collagen hydrogels with varying concentrations. The results illustrated that a group of cells generates significant spatio-temporal deformation of the matrix before and during the migration. Cells on soft collagen hydrogels migrate along tortuous paths, but, as the matrix stiffness increases, cell migration patterns become aligned with each other and show coordinated migration paths. As cells migrate, the matrix is locally compressed, resulting in a locally stiffened and dense matrix across the collagen concentration range studied.
Collapse
Affiliation(s)
- Altug Ozcelikkale
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA
| | - J Craig Dutton
- Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Frederick Grinnell
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Bumsoo Han
- School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907, USA .,Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA.,Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
20
|
Maccarana M, Svensson RB, Knutsson A, Giannopoulos A, Pelkonen M, Weis M, Eyre D, Warman M, Kalamajski S. Asporin-deficient mice have tougher skin and altered skin glycosaminoglycan content and structure. PLoS One 2017; 12:e0184028. [PMID: 28859141 PMCID: PMC5578652 DOI: 10.1371/journal.pone.0184028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 08/16/2017] [Indexed: 11/24/2022] Open
Abstract
The main structural component of connective tissues is fibrillar, cross-linked collagen whose fibrillogenesis can be modulated by Small Leucine-Rich Proteins/Proteoglycans (SLRPs). Not all SLRPs’ effects on collagen and extracellular matrix in vivo have been elucidated; one of the less investigated SLRPs is asporin. Here we describe the successful generation of an Aspn-/- mouse model and the investigation of the Aspn-/- skin phenotype. Functionally, Aspn-/- mice had an increased skin mechanical toughness, although there were no structural changes present on histology or immunohistochemistry. Electron microscopy analyses showed 7% thinner collagen fibrils in Aspn-/- mice (not statistically significant). Several matrix genes were upregulated, including collagens (Col1a1, Col1a2, Col3a1), matrix metalloproteinases (Mmp2, Mmp3) and lysyl oxidases (Lox, Loxl2), while lysyl hydroxylase (Plod2) was downregulated. Intriguingly no differences were observed in collagen protein content or in collagen cross-linking-related lysine oxidation or hydroxylation. The glycosaminoglycan content and structure in Aspn-/- skin was profoundly altered: chondroitin/dermatan sulfate was more than doubled and had an altered composition, while heparan sulfate was halved and had a decreased sulfation. Also, decorin and biglycan were doubled in Aspn-/- skin. Overall, asporin deficiency changes skin glycosaminoglycan composition, and decorin and biglycan content, which may explain the changes in skin mechanical properties.
Collapse
Affiliation(s)
- Marco Maccarana
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - René B. Svensson
- Institute of Sports Medicine, Bispebjerg Hospital, and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Anki Knutsson
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Antonis Giannopoulos
- Institute of Sports Medicine, Bispebjerg Hospital, and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Mea Pelkonen
- Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - MaryAnn Weis
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America
| | - David Eyre
- Department of Orthopaedics and Sports Medicine, University of Washington, Seattle, Washington, United States of America
| | - Matthew Warman
- Children’s Hospital Boston, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Sebastian Kalamajski
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
- * E-mail:
| |
Collapse
|
21
|
Iranmanesh F, Nazari MA. Finite Element Modeling of Avascular Tumor Growth Using a Stress-Driven Model. J Biomech Eng 2017; 139:2633189. [PMID: 28614573 DOI: 10.1115/1.4037038] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Indexed: 11/08/2022]
Abstract
Tumor growth being a multistage process has been investigated from different aspects. In the present study, an attempt is made to represent a constitutive-structure-based model of avascular tumor growth in which the effects of tensile stresses caused by collagen fibers are considered. Collagen fibers as a source of anisotropy in the structure of tissue are taken into account using a continuous fiber distribution formulation. To this end, a finite element modeling is implemented in which a neo-Hookean hyperelastic material is assigned to the tumor and its surrounding host. The tumor is supplied with a growth term. The growth term includes the effect of parameters such as nutrient concentration on the tumor growth and the tumor's solid phase content in the formulation. Results of the study revealed that decrease of solid phase is indicative of decrease in growth rate and the final steady-state value of tumor's radius. Moreover, fiber distribution affects the final shape of the tumor, and it could be used to control the shape and geometry of the tumor in complex morphologies. Finally, the findings demonstrated that the exerted stresses on the tumor increase as time passes. Compression of tumor cells leads to the reduction of tumor growth rate until it gradually reaches an equilibrium radius. This finding is in accordance with experimental data. Hence, this formulation can be deployed to evaluate both the residual stresses induced by growth and the mechanical interactions with the host tissue.
Collapse
Affiliation(s)
- Faezeh Iranmanesh
- Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439955961, Iran e-mail:
| | - Mohammad Ali Nazari
- Department of Mechanical Engineering, College of Engineering, University of Tehran, Tehran 1439955961, Iran e-mail:
| |
Collapse
|
22
|
Reese SP, Farhang N, Poulson R, Parkman G, Weiss JA. Nanoscale Imaging of Collagen Gels with Focused Ion Beam Milling and Scanning Electron Microscopy. Biophys J 2017; 111:1797-1804. [PMID: 27760365 DOI: 10.1016/j.bpj.2016.08.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 07/29/2016] [Accepted: 08/26/2016] [Indexed: 12/13/2022] Open
Abstract
In vitro polymerized type I collagen hydrogels have been used extensively as a model system for three-dimensional (3D) cell and tissue culture, studies of fibrillogenesis, and investigation of multiscale force transmission within connective tissues. The nanoscale organization of collagen fibrils plays an essential role in the mechanics of these gels and emergent cellular behavior in culture, yet quantifying 3D structure with nanoscale resolution to fully characterize fibril organization remains a significant technical challenge. In this study, we demonstrate that a new imaging modality, focused ion beam scanning electron microscopy (FIB-SEM), can be used to generate 3D image datasets for visualizing and quantifying complex nanoscale organization and morphometry in collagen gels. We polymerized gels at a number of concentrations and conditions commonly used for in vitro models, stained and embedded the samples, and performed FIB-SEM imaging. The resulting image data had a voxel size of 25 nm, which is the highest resolution 3D data of a collagen fibril network ever obtained for collagen gels. This resolution was essential for discerning individual fibrils, fibril paths, and their branching and grouping. The resulting volumetric images revealed that polymerization conditions have a significant impact on the complex fibril morphology of the gels. We segmented the fibril network and demonstrated that individual collagen fibrils can be tracked in 3D space, providing quantitative analysis of network descriptors such as fibril diameter distribution, length, branch points, and fibril aggregations. FIB-SEM 3D reconstructions showed considerably less lateral grouping and overlap of fibrils than standard 2D SEM images, likely due to artifacts in SEM introduced by dehydration. This study demonstrates the utility of FIB-SEM for 3D imaging of collagen gels and quantitative analysis of 3D fibril networks. We anticipate that the method will see application in future studies of structure-function relationships in collagen gels as well as native collagenous tissues.
Collapse
Affiliation(s)
- Shawn P Reese
- Bioengineering, University of Utah, Salt Lake City, Utah
| | | | - Randy Poulson
- Bioengineering, University of Utah, Salt Lake City, Utah
| | - Gennie Parkman
- Bioengineering, University of Utah, Salt Lake City, Utah
| | | |
Collapse
|
23
|
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
| |
Collapse
|
24
|
Hogrebe NJ, Reinhardt JW, Gooch KJ. Biomaterial microarchitecture: a potent regulator of individual cell behavior and multicellular organization. J Biomed Mater Res A 2016; 105:640-661. [DOI: 10.1002/jbm.a.35914] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 08/17/2016] [Accepted: 09/02/2016] [Indexed: 11/12/2022]
Affiliation(s)
- Nathaniel J. Hogrebe
- Department of Biomedical EngineeringThe Ohio State University270 Bevis Hall 1080 Carmack RdColumbus Ohio43210
| | - James W. Reinhardt
- Department of Biomedical EngineeringThe Ohio State University270 Bevis Hall 1080 Carmack RdColumbus Ohio43210
| | - Keith J. Gooch
- Department of Biomedical EngineeringThe Ohio State University270 Bevis Hall 1080 Carmack RdColumbus Ohio43210
- The Ohio State University, Davis Heart Lung Research Institute473 W 12th AveColumbus Ohio43210
| |
Collapse
|
25
|
Carey SP, Goldblatt ZE, Martin KE, Romero B, Williams RM, Reinhart-King CA. Local extracellular matrix alignment directs cellular protrusion dynamics and migration through Rac1 and FAK. Integr Biol (Camb) 2016; 8:821-35. [PMID: 27384462 PMCID: PMC4980151 DOI: 10.1039/c6ib00030d] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Cell migration within 3D interstitial microenvironments is sensitive to extracellular matrix (ECM) properties, but the mechanisms that regulate migration guidance by 3D matrix features remain unclear. To examine the mechanisms underlying the cell migration response to aligned ECM, which is prevalent at the tumor-stroma interface, we utilized time-lapse microscopy to compare the behavior of MDA-MB-231 breast adenocarcinoma cells within randomly organized and well-aligned 3D collagen ECM. We developed a novel experimental system in which cellular morphodynamics during initial 3D cell spreading served as a reductionist model for the complex process of matrix-directed 3D cell migration. Using this approach, we found that ECM alignment induced spatial anisotropy of cells' matrix probing by promoting protrusion frequency, persistence, and lengthening along the alignment axis and suppressing protrusion dynamics orthogonal to alignment. Preference for on-axis behaviors was dependent upon FAK and Rac1 signaling and translated across length and time scales such that cells within aligned ECM exhibited accelerated elongation, front-rear polarization, and migration relative to cells in random ECM. Together, these findings indicate that adhesive and protrusive signaling allow cells to respond to coordinated physical cues in the ECM, promoting migration efficiency and cell migration guidance by 3D matrix structure.
Collapse
Affiliation(s)
- Shawn P Carey
- Department of Biomedical Engineering, Cornell University, 302 Weill Hall, 526 Campus Rd, Ithaca, New York 14853, USA.
| | | | | | | | | | | |
Collapse
|
26
|
Magnesium Modifies the Structural Features of Enzymatically Mineralized Collagen Gels Affecting the Retraction Capabilities of Human Dermal Fibroblasts Embedded within This 3D System. MATERIALS 2016; 9:ma9060477. [PMID: 28773595 PMCID: PMC5456744 DOI: 10.3390/ma9060477] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 06/07/2016] [Accepted: 06/08/2016] [Indexed: 12/22/2022]
Abstract
Mineralized collagen gels have been developed as in vitro models to better understand the mechanisms regulating the calcification process and the behavior of a variety of cell types. The vast majority of data are related to stem cells and to osteoblast-like cells, whereas little information is available for dermal fibroblasts, although these cells have been associated with ectopic calcification and consequently to a number of pathological conditions. Therefore, we developed and characterized an enzymatically mineralized collagen gel in which fibroblasts were encapsulated within the 3D structure. MgCl2 was also added during gel polymerization, given its role as (i) modulator of ectopic calcification; (ii) component of biomaterials used for bone replacement; and (iii) constituent of pathological mineral deposits. Results demonstrate that, in a short time, an enzymatically mineralized collagen gel can be prepared in which mineral deposits and viable cells are homogeneously distributed. MgCl2 is present in mineral deposits and significantly affects collagen fibril assembly and organization. Consequently, cell shape and the ability of fibroblasts to retract collagen gels were modified. The development of three-dimensional (3D) mineralized collagen matrices with both different structural features and mineral composition together with the use of fibroblasts, as a prototype of soft connective tissue mesenchymal cells, may pave new ways for the study of ectopic calcification.
Collapse
|
27
|
Abstract
Biopolymer gels exhibit strain stiffening that is generally not seen in synthetic gels. Here, we investigate the strain-stiffening behavior in collagen I gels that demonstrate elasticity derived from a variety of sources including crosslinking through telopeptides, bundling through low-temperature gelation, and exogenous crosslinking with genipin. In all cases, it is found that these gels exhibit strain stiffening; in general, onset of strain stiffening occurs earlier, yield strain is lower, and degree of strain stiffening is smaller in higher concentration gels and in those displaying thick fibril bundles. Recovery after exposure to high strains is substantial and similar in all gels, suggesting that much of the stiffening comes from reversible network deformations. A key finding of this study is that collagen I gels of identical storage and loss moduli may display different nonlinear responses and different capacities to recover from high strain.
Collapse
Affiliation(s)
- Stéphanie Motte
- Department of Chemistry, Columbia University, New York, NY 10027
| | | |
Collapse
|
28
|
Three-dimensional force microscopy of cells in biopolymer networks. Nat Methods 2015; 13:171-6. [DOI: 10.1038/nmeth.3685] [Citation(s) in RCA: 209] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 10/19/2015] [Indexed: 01/11/2023]
|
29
|
Doyle AD, Carvajal N, Jin A, Matsumoto K, Yamada KM. Local 3D matrix microenvironment regulates cell migration through spatiotemporal dynamics of contractility-dependent adhesions. Nat Commun 2015; 6:8720. [PMID: 26548801 PMCID: PMC4643399 DOI: 10.1038/ncomms9720] [Citation(s) in RCA: 317] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 09/24/2015] [Indexed: 12/29/2022] Open
Abstract
The physical properties of two-dimensional (2D) extracellular matrices (ECMs) modulate cell adhesion dynamics and motility, but little is known about the roles of local microenvironmental differences in three-dimensional (3D) ECMs. Here we generate 3D collagen gels of varying matrix microarchitectures to characterize their regulation of 3D adhesion dynamics and cell migration. ECMs containing bundled fibrils demonstrate enhanced local adhesion-scale stiffness and increased adhesion stability through balanced ECM/adhesion coupling, whereas highly pliable reticular matrices promote adhesion retraction. 3D adhesion dynamics are locally regulated by ECM rigidity together with integrin/ECM association and myosin II contractility. Unlike 2D migration, abrogating contractility stalls 3D migration regardless of ECM pore size. We find force is not required for clustering of activated integrins on 3D native collagen fibrils. We propose that efficient 3D migration requires local balancing of contractility with ECM stiffness to stabilize adhesions, which facilitates the detachment of activated integrins from ECM fibrils. Little is known about how the physical properties of three dimensional (3D) extracellular matrices modulate cell adhesion dynamics. Here Doyle et al. generate 3D collagen gels of varying microarchitecture and quantify the effect on adhesion dynamics and cell motility.
Collapse
Affiliation(s)
- Andrew D Doyle
- Laboratory of Cell and Developmental Biology, Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Nicole Carvajal
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Albert Jin
- Laboratory of Cellular Imaging and Macromolecular Biophysics, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kazue Matsumoto
- Laboratory of Cell and Developmental Biology, Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kenneth M Yamada
- Laboratory of Cell and Developmental Biology, Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, Maryland 20892, USA
| |
Collapse
|
30
|
Doyle AD, Yamada KM. Mechanosensing via cell-matrix adhesions in 3D microenvironments. Exp Cell Res 2015; 343:60-66. [PMID: 26524505 DOI: 10.1016/j.yexcr.2015.10.033] [Citation(s) in RCA: 172] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 10/29/2015] [Indexed: 01/08/2023]
Abstract
The extracellular matrix (ECM) microenvironment plays a central role in cell migration by providing physiochemical information that influences overall cell behavior. Much of this external information is accessed by direct interaction of the cell with ECM ligands and structures via integrin-based adhesions that are hypothesized to act as mechanosensors for testing the surrounding microenvironment. Our current understanding of these mechanical complexes is derived primarily from studies of cellular adhesions formed on two-dimensional (2D) substrates in vitro. Yet the rules of cell/ECM engagement and mechanosensing in three-dimensional (3D) microenvironments are invariably more complex under both in vitro and in vivo conditions. Here we review the current understanding of how cellular mechanosensing occurs through adhesion complexes within 3D microenvironments and discuss how these mechanisms can vary and differ from interactions on 2D substrates.
Collapse
Affiliation(s)
- Andrew D Doyle
- Laboratory of Cell and Developmental Biology, Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Kenneth M Yamada
- Laboratory of Cell and Developmental Biology, Cell Biology Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
31
|
Feng Z, Ishiguro Y, Fujita K, Kosawada T, Nakamura T, Sato D, Kitajima T, Umezu M. A fibril-based structural constitutive theory reveals the dominant role of network characteristics on the mechanical behavior of fibroblast-compacted collagen gels. Biomaterials 2015; 67:365-81. [DOI: 10.1016/j.biomaterials.2015.07.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/17/2015] [Accepted: 07/20/2015] [Indexed: 01/02/2023]
|
32
|
Burke KA, Dawes RP, Cheema MK, Van Hove A, Benoit DSW, Perry SW, Brown E. Second-harmonic generation scattering directionality predicts tumor cell motility in collagen gels. JOURNAL OF BIOMEDICAL OPTICS 2015; 20:051024. [PMID: 25625899 PMCID: PMC4306817 DOI: 10.1117/1.jbo.20.5.051024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/09/2014] [Indexed: 05/24/2023]
Abstract
Second-harmonic generation (SHG) allows for the analysis of tumor collagen structural changes throughout metastatic progression. SHG directionality, measured through the ratio of the forward-propagating to backward-propagating signal (F/B ratio), is affected by collagen fibril diameter, spacing, and disorder of fibril packing within a fiber. As tumors progress, these parameters evolve, producing concurrent changes in F/B. It has been recently shown that the F/B of highly metastatic invasive ductal carcinoma (IDC) breast tumors is significantly different from less metastatic tumors. This suggests a possible relationship between the microstructure of collagen, as measured by the F/B, and the ability of tumor cells to locomote through that collagen. Utilizing in vitro collagen gels of different F/B ratios, we explored the relationship between collagen microstructure and motility of tumor cells in a “clean” environment, free of the myriad cells, and signals found in in vivo. We found a significant relationship between F/B and the total distance traveled by the tumor cell, as well as both the average and maximum velocities of the cells. Consequently, one possible mechanism underlying the observed relationship between tumor F/B and metastatic output in IDC patient samples is a direct influence of collagen structure on tumor cell motility.
Collapse
MESH Headings
- Animals
- Breast Neoplasms/metabolism
- Breast Neoplasms/pathology
- Carcinoma, Ductal, Breast/metabolism
- Carcinoma, Ductal, Breast/pathology
- Cell Line, Tumor
- Cell Movement
- Collagen/chemistry
- Disease Progression
- Female
- Gels/chemistry
- Image Processing, Computer-Assisted
- Mice
- Mice, Inbred BALB C
- Microscopy, Fluorescence, Multiphoton/instrumentation
- Microscopy, Fluorescence, Multiphoton/methods
- Neoplasm Metastasis
- Signal Transduction
Collapse
Affiliation(s)
- Kathleen A. Burke
- University of Rochester, Department of Biomedical Engineering, 207 Robert B. Goergen Hall, P.O. Box 270168, Rochester, New York 14627, United States
| | - Ryan P. Dawes
- University of Rochester, Department of Neurobiology and Anatomy, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Mehar K. Cheema
- State University of New York at Stony Brook, Department of Biomedical Engineering, Stony Brook, New York 11790, United States
| | - Amy Van Hove
- University of Rochester, Department of Biomedical Engineering, 207 Robert B. Goergen Hall, P.O. Box 270168, Rochester, New York 14627, United States
| | - Danielle S. W. Benoit
- University of Rochester, Department of Biomedical Engineering, 207 Robert B. Goergen Hall, P.O. Box 270168, Rochester, New York 14627, United States
- University of Rochester, Department of Biomedical Genetics, 601 Elmwood Avenue, Rochester, New York 14642, United States
- University of Rochester, Department of Chemical Engineering, 206 Gavett Hall, Rochester, New York 14627, United States
- University of Rochester Medical Center, Center for Musculoskeletal Research, 601 Elmwood Avenue, Rochester, New York 14642, United States
| | - Seth W. Perry
- University of Rochester, Department of Biomedical Engineering, 207 Robert B. Goergen Hall, P.O. Box 270168, Rochester, New York 14627, United States
| | - Edward Brown
- University of Rochester, Department of Biomedical Engineering, 207 Robert B. Goergen Hall, P.O. Box 270168, Rochester, New York 14627, United States
- University of Rochester, Department of Neurobiology and Anatomy, 601 Elmwood Avenue, Rochester, New York 14642, United States
| |
Collapse
|
33
|
Mohammadi H, Arora PD, Simmons CA, Janmey PA, McCulloch CA. Inelastic behaviour of collagen networks in cell-matrix interactions and mechanosensation. J R Soc Interface 2015; 12:20141074. [PMID: 25392399 PMCID: PMC4277099 DOI: 10.1098/rsif.2014.1074] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 10/17/2014] [Indexed: 12/15/2022] Open
Abstract
The mechanical properties of extracellular matrix proteins strongly influence cell-induced tension in the matrix, which in turn influences cell function. Despite progress on the impact of elastic behaviour of matrix proteins on cell-matrix interactions, little is known about the influence of inelastic behaviour, especially at the large and slow deformations that characterize cell-induced matrix remodelling. We found that collagen matrices exhibit deformation rate-dependent behaviour, which leads to a transition from pronounced elastic behaviour at fast deformations to substantially inelastic behaviour at slow deformations (1 μm min(-1), similar to cell-mediated deformation). With slow deformations, the inelastic behaviour of floating gels was sensitive to collagen concentration, whereas attached gels exhibited similar inelastic behaviour independent of collagen concentration. The presence of an underlying rigid support had a similar effect on cell-matrix interactions: cell-induced deformation and remodelling were similar on 1 or 3 mg ml(-1) attached collagen gels while deformations were two- to fourfold smaller in floating gels of high compared with low collagen concentration. In cross-linked collagen matrices, which did not exhibit inelastic behaviour, cells did not respond to the presence of the underlying rigid foundation. These data indicate that at the slow rates of collagen compaction generated by fibroblasts, the inelastic responses of collagen gels, which are influenced by collagen concentration and the presence of an underlying rigid foundation, are important determinants of cell-matrix interactions and mechanosensation.
Collapse
Affiliation(s)
- Hamid Mohammadi
- Matrix Dynamics Group, University of Toronto, Toronto, Ontario, Canada
| | - Pamma D Arora
- Matrix Dynamics Group, University of Toronto, Toronto, Ontario, Canada
| | - Craig A Simmons
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Paul A Janmey
- Institute for Medicine and Engineering, University of Pennsylvania, Philadelphia, PA, USA
| | | |
Collapse
|
34
|
Edgar LT, Hoying JB, Utzinger U, Underwood CJ, Krishnan L, Baggett BK, Maas SA, Guilkey JE, Weiss JA. Mechanical interaction of angiogenic microvessels with the extracellular matrix. J Biomech Eng 2014; 136:021001. [PMID: 24441831 DOI: 10.1115/1.4026471] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 02/05/2013] [Indexed: 12/28/2022]
Abstract
Angiogenesis is the process by which new blood vessels sprout from existing blood vessels, enabling new vascular elements to be added to an existing vasculature. This review discusses our investigations into the role of cell-matrix mechanics in the mechanical regulation of angiogenesis. The experimental aspects of the research are based on in vitro experiments using an organ culture model of sprouting angiogenesis with the goal of developing new treatments and techniques to either promote or inhibit angiogenic outgrowth, depending on the application. Computational simulations were performed to simulate angiogenic growth coupled to matrix deformation, and live two-photon microscopy was used to obtain insight into the dynamic mechanical interaction between angiogenic neovessels and the extracellular matrix. In these studies, we characterized how angiogenic neovessels remodel the extracellular matrix (ECM) and how properties of the matrix such as density and boundary conditions influence vascular growth and alignment. Angiogenic neovessels extensively deform and remodel the matrix through a combination of applied traction, proteolytic activity, and generation of new cell-matrix adhesions. The angiogenic phenotype within endothelial cells is promoted by ECM deformation and remodeling. Sensitivity analysis using our finite element model of angiogenesis suggests that cell-generated traction during growth is the most important parameter controlling the deformation of the matrix and, therefore, angiogenic growth and remodeling. Live two-photon imaging has also revealed numerous neovessel behaviors during angiogenesis that are poorly understood such as episodic growth/regression, neovessel colocation, and anastomosis. Our research demonstrates that the topology of a resulting vascular network can be manipulated directly by modifying the mechanical interaction between angiogenic neovessels and the matrix.
Collapse
|
35
|
Collagen I self-assembly: revealing the developing structures that generate turbidity. Biophys J 2014; 106:1822-31. [PMID: 24739181 DOI: 10.1016/j.bpj.2014.03.011] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/13/2014] [Accepted: 03/11/2014] [Indexed: 01/13/2023] Open
Abstract
Type I collagen gels are routinely used in biophysical studies and bioengineering applications. The structural and mechanical properties of these fibrillar matrices depend on the conditions under which collagen fibrillogenesis proceeds, and developing a fuller understanding of this process will enhance control over gel properties. Turbidity measurements have long been the method of choice for monitoring developing gels, whereas imaging methods are regularly used to visualize fully developed gels. In this study, turbidity and confocal reflectance microscopy (CRM) were simultaneously employed to track collagen fibrillogenesis and reconcile the information reported by the two techniques, with confocal fluorescence microscopy (CFM) used to supplement information about early events in fibrillogenesis. Time-lapse images of 0.5 mg/ml, 1.0 mg/ml, and 2.0 mg/ml acid-solubilized collagen I gels forming at 27°C, 32°C, and 37°C were collected. It was found that in situ turbidity measured in a scanning transmittance configuration was interchangeable with traditional turbidity measurements using a spectrophotometer. CRM and CFM were employed to reveal the structures responsible for the turbidity that develops during collagen self-assembly. Information from CRM and transmittance images was collapsed into straightforward single variables; total intensity in CRM images tracked turbidity development closely for all collagen gels investigated, and the two techniques were similarly sensitive to fibril number and dimension. Complementary CRM, CFM, and in situ turbidity measurements revealed that fibril and network formation occurred before substantial turbidity was present, and the majority of increasing turbidity during collagen self-assembly was due to increasing fibril thickness.
Collapse
|
36
|
Antoine EE, Vlachos PP, Rylander MN. Review of collagen I hydrogels for bioengineered tissue microenvironments: characterization of mechanics, structure, and transport. TISSUE ENGINEERING. PART B, REVIEWS 2014; 20:683-96. [PMID: 24923709 PMCID: PMC4241868 DOI: 10.1089/ten.teb.2014.0086] [Citation(s) in RCA: 326] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Accepted: 05/29/2014] [Indexed: 01/13/2023]
Abstract
Type I collagen hydrogels have been used successfully as three-dimensional substrates for cell culture and have shown promise as scaffolds for engineered tissues and tumors. A critical step in the development of collagen hydrogels as viable tissue mimics is quantitative characterization of hydrogel properties and their correlation with fabrication parameters, which enables hydrogels to be tuned to match specific tissues or fulfill engineering requirements. A significant body of work has been devoted to characterization of collagen I hydrogels; however, due to the breadth of materials and techniques used for characterization, published data are often disjoint and hence their utility to the community is reduced. This review aims to determine the parameter space covered by existing data and identify key gaps in the literature so that future characterization and use of collagen I hydrogels for research can be most efficiently conducted. This review is divided into three sections: (1) relevant fabrication parameters are introduced and several of the most popular methods of controlling and regulating them are described, (2) hydrogel properties most relevant for tissue engineering are presented and discussed along with their characterization techniques, (3) the state of collagen I hydrogel characterization is recapitulated and future directions are proposed. Ultimately, this review can serve as a resource for selection of fabrication parameters and material characterization methodologies in order to increase the usefulness of future collagen-hydrogel-based characterization studies and tissue engineering experiments.
Collapse
Affiliation(s)
| | - Pavlos P. Vlachos
- School of Mechanical Engineering, Purdue University, West Lafayette, Indiana
| | - Marissa Nichole Rylander
- Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia
- Virginia Tech-Wake Forest School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, Virginia
| |
Collapse
|
37
|
Edgar LT, Maas SA, Guilkey JE, Weiss JA. A coupled model of neovessel growth and matrix mechanics describes and predicts angiogenesis in vitro. Biomech Model Mechanobiol 2014; 14:767-82. [PMID: 25429840 DOI: 10.1007/s10237-014-0635-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Accepted: 11/12/2014] [Indexed: 12/26/2022]
Abstract
During angiogenesis, sprouting microvessels interact with the extracellular matrix (ECM) by degrading and reorganizing the matrix, applying traction forces, and producing deformation. Morphometric features of the resulting microvascular network are affected by the interaction between the matrix and angiogenic microvessels. The objective of this study was to develop a continuous-discrete modeling approach to simulate mechanical interactions between growing neovessels and the deformation of the matrix in vitro. This was accomplished by coupling an existing angiogenesis growth model which uses properties of the ECM to regulate angiogenic growth with the nonlinear finite element software FEBio (www.febio.org). FEBio solves for the deformation and remodeling of the matrix caused by active stress generated by neovessel sprouts, and this deformation was used to update the ECM into the current configuration. After mesh resolution and parameter sensitivity studies, the model was used to accurately predict vascular alignment for various matrix boundary conditions. Alignment primarily arises passively as microvessels convect with the deformation of the matrix, but active alignment along collagen fibrils plays a role as well. Predictions of alignment were most sensitive to the range over which active stresses were applied and the viscoelastic time constant in the material model. The computational framework provides a flexible platform for interpreting in vitro investigations of vessel-matrix interactions, predicting new experiments, and simulating conditions that are outside current experimental capabilities.
Collapse
Affiliation(s)
- Lowell T Edgar
- Department of Bioengineering, University of Utah, 72 South Central Campus Drive, Rm 2646, Salt Lake City, UT, 84112, USA
| | | | | | | |
Collapse
|
38
|
A histological and mechanical analysis of the cardiac lead-tissue interface: implications for lead extraction. Acta Biomater 2014; 10:2200-8. [PMID: 24434537 DOI: 10.1016/j.actbio.2014.01.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/19/2013] [Accepted: 01/07/2014] [Indexed: 11/21/2022]
Abstract
The major risks of pacemaker and implantable cardioverter defibrillator extraction are attributable to the fibrotic tissue that encases them in situ, yet little is known about the cellular and functional properties of this response. In the present research, we performed a histological and mechanical analysis of human tissue collected from the lead-tissue interface to better understand this process and provide insights for the improvement of lead design and extraction. The lead-tissue interface consisted of a thin cellular layer underlying a smooth, acellular surface, followed by a circumferentially organized collagen-rich matrix. 51.8±4.9% of cells were myofibroblasts via immunohistochemistry, with these cells displaying a similar circumferential organization. Upon mechanical testing, samples exhibited a triphasic force-displacement response consisting of a toe region during initial tensioning, a linear elastic region and a yield and failure region. Mean fracture load was 5.6±2.1N, and mean circumferential stress at failure was 9.5±4.1MPa. While the low cellularity and fibrotic composition of tissue observed herein is consistent with a foreign body reaction to an implanted material, the significant myofibroblast response provides a mechanical explanation for the contractile forces complicating extractions. Moreover, the tensile properties of this tissue suggest the feasibility of circumferential mechanical tissue disruption, similar to balloon angioplasty devices, as a novel approach to assist with lead extraction.
Collapse
|
39
|
Nonlinear strain stiffening is not sufficient to explain how far cells can feel on fibrous protein gels. Biophys J 2014; 105:11-20. [PMID: 23823219 DOI: 10.1016/j.bpj.2013.05.032] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 05/06/2013] [Accepted: 05/10/2013] [Indexed: 01/15/2023] Open
Abstract
Recent observations suggest that cells on fibrous extracellular matrix materials sense mechanical signals over much larger distances than they do on linearly elastic synthetic materials. In this work, we systematically investigate the distance fibroblasts can sense a rigid boundary through fibrous gels by quantifying the spread areas of human lung fibroblasts and 3T3 fibroblasts cultured on sloped collagen and fibrin gels. The cell areas gradually decrease as gel thickness increases from 0 to 150 μm, with characteristic sensing distances of >65 μm below fibrin and collagen gels, and spreading affected on gels as thick as 150 μm. These results demonstrate that fibroblasts sense deeper into collagen and fibrin gels than they do into polyacrylamide gels, with the latter exhibiting characteristic sensing distances of <5 μm. We apply finite-element analysis to explore the role of strain stiffening, a characteristic mechanical property of collagen and fibrin that is not observed in polyacrylamide, in facilitating mechanosensing over long distances. Our analysis shows that the effective stiffness of both linear and nonlinear materials sharply increases once the thickness is reduced below 5 μm, with only a slight enhancement in sensitivity to depth for the nonlinear material at very low thickness and high applied traction. Multiscale simulations with a simplified geometry predict changes in fiber alignment deep into the gel and a large increase in effective stiffness with a decrease in substrate thickness that is not predicted by nonlinear elasticity. These results suggest that the observed cell-spreading response to gel thickness is not explained by the nonlinear strain-stiffening behavior of the material alone and is likely due to the fibrous nature of the proteins.
Collapse
|
40
|
Whittington CF, Brandner E, Teo KY, Han B, Nauman E, Voytik-Harbin SL. Oligomers modulate interfibril branching and mass transport properties of collagen matrices. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2013; 19:1323-33. [PMID: 23842082 PMCID: PMC3778042 DOI: 10.1017/s1431927613001931] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Mass transport within collagen-based matrices is critical to tissue development, repair, and pathogenesis, as well as the design of next-generation tissue engineering strategies. This work shows how collagen precursors, specified by intermolecular cross-link composition, provide independent control of collagen matrix mechanical and transport properties. Collagen matrices were prepared from tissue-extracted monomers or oligomers. Viscoelastic behavior was measured in oscillatory shear and unconfined compression. Matrix permeability and diffusivity were measured using gravity-driven permeametry and integrated optical imaging, respectively. Both collagen types showed an increase in stiffness and permeability hindrance with increasing collagen concentration (fibril density); however, different physical property–concentration relationships were noted. Diffusivity was not affected by concentration for either collagen type over the range tested. In general, oligomer matrices exhibited a substantial increase in stiffness and only a modest decrease in transport properties when compared with monomer matrices prepared at the same concentration. The observed differences in viscoelastic and transport properties were largely attributed to increased levels of interfibril branching within oligomer matrices. The ability to relate physical properties to relevant microstructure parameters, including fibril density and interfibril branching, is expected to advance the understanding of cell–matrix signaling, as well as facilitate model-based prediction and design of matrix-based therapeutic strategies.
Collapse
Affiliation(s)
- Catherine F. Whittington
- Weldon School of Biomedical Engineering, Collage of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Eric Brandner
- Weldon School of Biomedical Engineering, Collage of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Ka Yaw Teo
- School of Mechanical Engineering, College of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Bumsoo Han
- Weldon School of Biomedical Engineering, Collage of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
- School of Mechanical Engineering, College of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Eric Nauman
- Weldon School of Biomedical Engineering, Collage of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
- School of Mechanical Engineering, College of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
- Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana, 47907, USA
| | - Sherry L. Voytik-Harbin
- Weldon School of Biomedical Engineering, Collage of Engineering, Purdue University, West Lafayette, Indiana, 47907, USA
- Department of Basic Medical Sciences, School of Veterinary Medicine, Purdue University, West Lafayette, Indiana, 47907, USA
| |
Collapse
|
41
|
Reese SP, Underwood CJ, Weiss JA. Effects of decorin proteoglycan on fibrillogenesis, ultrastructure, and mechanics of type I collagen gels. Matrix Biol 2013; 32:414-23. [PMID: 23608680 DOI: 10.1016/j.matbio.2013.04.004] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2012] [Revised: 03/17/2013] [Accepted: 04/01/2013] [Indexed: 11/24/2022]
Abstract
The proteoglycan decorin is known to affect both the fibrillogenesis and the resulting ultrastructure of in vitro polymerized collagen gels. However, little is known about its effects on mechanical properties. In this study, 3D collagen gels were polymerized into tensile test specimens in the presence of decorin proteoglycan, decorin core protein, or dermatan sulfate (DS). Collagen fibrillogenesis, ultrastructure, and mechanical properties were then quantified using a turbidity assay, 2 forms of microscopy (SEM and confocal), and tensile testing. The presence of decorin proteoglycan or core protein decreased the rate and ultimate turbidity during fibrillogenesis and decreased the number of fibril aggregates (fibers) compared to control gels. The addition of decorin and core protein increased the linear modulus by a factor of 2 compared to controls, while the addition of DS reduced the linear modulus by a factor of 3. Adding decorin after fibrillogenesis had no effect, suggesting that decorin must be present during fibrillogenesis to increase the mechanical properties of the resulting gels. These results show that the inclusion of decorin proteoglycan during fibrillogenesis of type I collagen increases the modulus and tensile strength of resulting collagen gels. The increase in mechanical properties when polymerization occurs in the presence of the decorin proteoglycan is due to a reduction in the aggregation of fibrils into larger order structures such as fibers and fiber bundles.
Collapse
Affiliation(s)
- Shawn P Reese
- Department of Bioengineering, University of Utah, United States
| | | | | |
Collapse
|
42
|
Susilo ME, Bell BJ, Roeder BA, Voytik-Harbin SL, Kokini K, Nauman EA. Prediction of equibiaxial loading stress in collagen-based extracellular matrix using a three-dimensional unit cell model. Acta Biomater 2013; 9:5544-53. [PMID: 23107798 DOI: 10.1016/j.actbio.2012.10.028] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2012] [Revised: 10/14/2012] [Accepted: 10/19/2012] [Indexed: 10/27/2022]
Abstract
Mechanical signals are important factors in determining cell fate. Therefore, insights as to how mechanical signals are transferred between the cell and its surrounding three-dimensional collagen fibril network will provide a basis for designing the optimum extracellular matrix (ECM) microenvironment for tissue regeneration. Previously we described a cellular solid model to predict fibril microstructure-mechanical relationships of reconstituted collagen matrices due to unidirectional loads (Acta Biomater 2010;6:1471-86). The model consisted of representative volume elements made up of an interconnected network of flexible struts. The present study extends this work by adapting the model to account for microstructural anisotropy of the collagen fibrils and a biaxial loading environment. The model was calibrated based on uniaxial tensile data and used to predict the equibiaxial tensile stress-stretch relationship. Modifications to the model significantly improved its predictive capacity for equibiaxial loading data. With a comparable fibril length (model 5.9-8μm, measured 7.5μm) and appropriate fibril anisotropy the anisotropic model provides a better representation of the collagen fibril microstructure. Such models are important tools for tissue engineering because they facilitate prediction of microstructure-mechanical relationships for collagen matrices over a wide range of microstructures and provide a framework for predicting cell-ECM interactions.
Collapse
|
43
|
Harjanto D, Zaman MH. Modeling extracellular matrix reorganization in 3D environments. PLoS One 2013; 8:e52509. [PMID: 23341900 PMCID: PMC3544844 DOI: 10.1371/journal.pone.0052509] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 11/19/2012] [Indexed: 01/03/2023] Open
Abstract
Extracellular matrix (ECM) remodeling is a key physiological process that occurs in a number of contexts, including cell migration, and is especially important for cellular form and function in three-dimensional (3D) matrices. However, there have been few attempts to computationally model how cells modify their environment in a manner that accounts for both cellular properties and the architecture of the surrounding ECM. To this end, we have developed and validated a novel model to simulate matrix remodeling that explicitly defines cells in a 3D collagenous matrix. In our simulation, cells can degrade, deposit, or pull on local fibers, depending on the fiber density around each cell. The cells can also move within the 3D matrix. Different cell phenotypes can be modeled by varying key cellular parameters. Using the model we have studied how two model cancer cell lines, of differing invasiveness, modify matrices with varying fiber density in their vicinity by tracking the metric of fraction of matrix occupied by fibers. Our results quantitatively demonstrate that in low density environments, cells deposit more collagen to uniformly increase fibril fraction. On the other hand, in higher density environments, the less invasive model cell line reduced the fibril fraction as compared to the highly invasive phenotype. These results show good qualitative and quantitative agreement with existing experimental literature. Our simulation is therefore able to function as a novel platform to provide new insights into the clinically relevant and physiologically critical process of matrix remodeling by helping identify critical parameters that dictate cellular behavior in complex native-like environments.
Collapse
Affiliation(s)
- Dewi Harjanto
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Muhammad H. Zaman
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
44
|
Duncan NA, Bruehlmann SB, Hunter CJ, Shao X, Kelly EJ. In situ cell-matrix mechanics in tendon fascicles and seeded collagen gels: implications for the multiscale design of biomaterials. Comput Methods Biomech Biomed Engin 2012; 17:39-47. [PMID: 23237459 DOI: 10.1080/10255842.2012.742075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Designing biomaterials to mimic and function within the complex mechanobiological conditions of connective tissues requires a detailed understanding of the micromechanical environment of the cell. The objective of our study was to measure the in situ cell-matrix strains from applied tension in both tendon fascicles and cell-seeded type I collagen scaffolds using laser scanning confocal microscopy techniques. Tendon fascicles and collagen gels were fluorescently labelled to simultaneously visualise the extracellular matrix and cell nuclei under applied tensile strains of 5%. There were significant differences observed in the micromechanics at the cell-matrix scale suggesting that the type I collagen scaffold did not replicate the pattern of native tendon strains. In particular, although the overall in situ tensile strains in the matrix were quite similar (∼2.5%) between the tendon fascicles and the collagen scaffolds, there were significant differences at the cell-matrix boundary with visible shear across cell nuclei of >1 μm measured in native tendon which was not observed at all in the collagen scaffolds. Similarly, there was significant non-uniformity of intercellular strains with relative sliding observed between cell rows in tendon which again was not observed in the collagen scaffolds where the strain environment was much more uniform. If the native micromechanical environment is not replicated in biomaterial scaffolds, then the cells may receive incorrect or mixed mechanical signals which could affect their biosynthetic response to mechanical load in tissue engineering applications. This study highlights the importance of considering the microscale mechanics in the design of biomaterial scaffolds and the need to incorporate such features in computational models of connective tissues.
Collapse
Affiliation(s)
- Neil A Duncan
- a McCaig Institute for Bone and Joint Health, University of Calgary , 2500 University Drive, NW, Calgary AB Canada T2N 1N4
| | | | | | | | | |
Collapse
|
45
|
Han WM, Nerurkar NL, Smith LJ, Jacobs NT, Mauck RL, Elliott DM. Multi-scale structural and tensile mechanical response of annulus fibrosus to osmotic loading. Ann Biomed Eng 2012; 40:1610-21. [PMID: 22314837 DOI: 10.1007/s10439-012-0525-4] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/27/2012] [Indexed: 01/04/2023]
Abstract
This study investigates differential multi-scale structure and function relationships of the outer and inner annulus fibrosus (AF) to osmotic swelling in different buffer solutions by quantifying tensile mechanics, glycoasamino-glycan(GAG) content, water content and tissue swelling, and collagen fibril ultrastructure. In the outer AF, the tensile modulus decreased by over 70% with 0.15 M PBS treatment but was unchanged with 2 M PBS treatment. Moreover, the modulus loss following 0.15 M PBS treatment was reversed when followed by 2 M PBS treatment, potentially from increased interfibrillar and interlamellar shearing associated with fibril swelling. In contrast, the inner AF tensile modulus was unchanged by 0.15 M PBS treatment and increased following 2 M treatment. Transmission electron microscopy revealed that the mean collagen fibril diameters of the untreated outer and inner AF were 87.8 ± 27.9 and 71.0 ± 26.9 nm, respectively. In the outer AF, collagen fibril swelling was observed with both 0.15 M and 2 M PBS treatments, but inherently low GAG content remained unchanged. In the inner AF, 2 M PBS treatment caused fibril swelling and GAG loss, suggesting that GAG plays a role in maintaining the structure of collagen fibrils leading to modulation of the native tissue mechanical properties. These results demonstrate important regional variations in structure and composition, and their influence on the heterogeneous mechanics of the AF. Moreover, because the composition and structure is altered as a consequence of progressive disk degeneration, quantification of these interactions is critical for study of the AF pathogenesis of degeneration and tissue engineering
Collapse
Affiliation(s)
- Woojin M Han
- Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | | | | | |
Collapse
|
46
|
Bell BJ, Nauman E, Voytik-Harbin SL. Multiscale strain analysis of tissue equivalents using a custom-designed biaxial testing device. Biophys J 2012; 102:1303-12. [PMID: 22455913 DOI: 10.1016/j.bpj.2012.02.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2011] [Revised: 12/21/2011] [Accepted: 02/03/2012] [Indexed: 01/13/2023] Open
Abstract
Mechanical signals transferred between a cell and its extracellular matrix play an important role in regulating fundamental cell behavior. To further define the complex mechanical interactions between cells and matrix from a multiscale perspective, a biaxial testing device was designed and built. Finite element analysis was used to optimize the cruciform specimen geometry so that stresses within the central region were concentrated and homogenous while minimizing shear and grip effects. This system was used to apply an equibiaxial loading and unloading regimen to fibroblast-seeded tissue equivalents. Digital image correlation and spot tracking were used to calculate three-dimensional strains and associated strain transfer ratios at macro (construct), meso, matrix (collagen fibril), cell (mitochondria), and nuclear levels. At meso and matrix levels, strains in the 1- and 2-direction were statistically similar throughout the loading-unloading cycle. Interestingly, a significant amplification of cellular and nuclear strains was observed in the direction perpendicular to the cell axis. Findings indicate that strain transfer is dependent upon local anisotropies generated by the cell-matrix force balance. Such multiscale approaches to tissue mechanics will assist in advancement of modern biomechanical theories as well as development and optimization of preconditioning regimens for functional engineered tissue constructs.
Collapse
Affiliation(s)
- B J Bell
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA
| | | | | |
Collapse
|
47
|
Carey SP, Kraning-Rush CM, Williams RM, Reinhart-King CA. Biophysical control of invasive tumor cell behavior by extracellular matrix microarchitecture. Biomaterials 2012; 33:4157-65. [PMID: 22405848 DOI: 10.1016/j.biomaterials.2012.02.029] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 02/14/2012] [Indexed: 01/16/2023]
Abstract
Fibrillar collagen gels, which are used extensively in vitro to study tumor-microenvironment interactions, are composed of a cell-instructive network of interconnected fibers and pores whose organization is sensitive to polymerization conditions such as bulk concentration, pH, and temperature. Using confocal reflectance microscopy and image autocorrelation analysis to quantitatively assess gel microarchitecture, we show that additional polymerization parameters including culture media formulation and gel thickness significantly affect the dimensions and organization of fibers and pores in collagen gels. These findings enabled the development of a three-dimensional culture system in which cell-scale gel microarchitecture was decoupled from bulk gel collagen concentration. Interestingly, morphology and migration characteristics of embedded MDA-MB-231 cells were sensitive to gel microarchitecture independently of collagen gel concentration. Cells adopted a polarized, motile phenotype in gels with larger fibers and pores and a rounded or stellate, less motile phenotype in gels with small fibers and pores regardless of bulk gel density. Conversely, cell proliferation was sensitive to gel concentration but not microarchitecture. These results indicate that cell-scale gel microarchitecture may trump bulk-scale gel density in controlling specific cell behaviors, underscoring the biophysical role of gel microarchitecture in influencing cell behavior.
Collapse
Affiliation(s)
- Shawn P Carey
- Department of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | | | | | | |
Collapse
|
48
|
Thambyah A, Zhao JY, Bevill SL, Broom ND. Macro-, micro- and ultrastructural investigation of how degeneration influences the response of cartilage to loading. J Mech Behav Biomed Mater 2012; 5:206-15. [DOI: 10.1016/j.jmbbm.2011.08.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Revised: 08/26/2011] [Accepted: 08/30/2011] [Indexed: 10/17/2022]
|
49
|
Harjanto D, Maffei JS, Zaman MH. Quantitative analysis of the effect of cancer invasiveness and collagen concentration on 3D matrix remodeling. PLoS One 2011; 6:e24891. [PMID: 21980363 PMCID: PMC3181246 DOI: 10.1371/journal.pone.0024891] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Accepted: 08/23/2011] [Indexed: 12/31/2022] Open
Abstract
Extracellular matrix (ECM) remodeling is a key component of cell migration and tumor metastasis, and has been associated with cancer progression. Despite the importance of matrix remodeling, systematic and quantitative studies on the process have largely been lacking. Furthermore, it remains unclear if the disrupted tensional homeostasis characteristic of malignancy is due to initially altered ECM and tissue properties, or to the alteration of the tissue by tumor cells. To explore these questions, we studied matrix remodeling by two different prostate cancer cell lines in a three-dimensional collagen system. Over one week, we monitored structural changes in gels of varying collagen content using confocal reflection microscopy and quantitative image analysis, tracking metrics of fibril fraction, pore size, and fiber length and diameter. Gels that were seeded with no cells (control), LNCaP cells, and DU-145 cells were quantitatively compared. Gels with higher collagen content initially had smaller pore sizes and higher fibril fractions, as expected. However, over time, LNCaP- and DU-145-populated matrices showed different structural properties compared both to each other and to the control gels, with LNCaP cells appearing to favor microenvironments with lower collagen fiber fractions and larger pores than DU-145 cells. We posit that the DU-145 cells' preference for denser matrices is due to their higher invasiveness and proteolytic capabilities. Inhibition of matrix proteases resulted in reduced fibril fractions for high concentration gels seeded with either cell type, supporting our hypothesis. Our novel quantitative results probe the dynamics of gel remodeling in three dimensions and suggest that prostate cancer cells remodel their ECM in a synergistic manner that is dependent on both initial matrix properties as well as their invasiveness.
Collapse
Affiliation(s)
- Dewi Harjanto
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Joseph S. Maffei
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
| | - Muhammad H. Zaman
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
50
|
Gillette BM, Rossen NS, Das N, Leong D, Wang M, Dugar A, Sia SK. Engineering extracellular matrix structure in 3D multiphase tissues. Biomaterials 2011; 32:8067-76. [PMID: 21840047 DOI: 10.1016/j.biomaterials.2011.05.043] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 05/12/2011] [Indexed: 01/12/2023]
Abstract
In native tissues, microscale variations in the extracellular matrix (ECM) structure can drive different cellular behaviors. Although control over ECM structure could prove useful in tissue engineering and in studies of cellular behavior, isotropic 3D matrices poorly replicate variations in local microenvironments. In this paper, we demonstrate a method to engineer local variations in the density and size of collagen fibers throughout 3D tissues. The results showed that, in engineered multiphase tissues, the structures of collagen fibers in both the bulk ECM phases (as measured by mesh size and width of fibers) as well as at tissue interfaces (as measured by density of fibers and thickness of tissue interfaces) could be modulated by varying the collagen concentrations and gelling temperatures. As the method makes use of a previously published technique for tissue bonding, we also confirmed that significant adhesion strength at tissue interfaces was achieved under all conditions tested. Hence, this study demonstrates how collagen fiber structures can be engineered within all regions of a multiphase tissue scaffold by exploiting knowledge of collagen assembly, and presents an approach to engineer local collagen structure that complements methods such as flow alignment and electrospinning.
Collapse
Affiliation(s)
- Brian M Gillette
- Department of Biomedical Engineering Columbia University, New York, NY 10027, USA
| | | | | | | | | | | | | |
Collapse
|