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Ficarella E, Minooei M, Santoro L, Toma E, Trentadue B, De Spirito M, Papi M, Pruncu CI, Lamberti L. Visco-Hyperelastic Characterization of the Equine Immature Zona Pellucida. MATERIALS 2021; 14:ma14051223. [PMID: 33807624 PMCID: PMC7961360 DOI: 10.3390/ma14051223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 12/13/2022]
Abstract
This article presents a very detailed study on the mechanical characterization of a highly nonlinear material, the immature equine zona pellucida (ZP) membrane. The ZP is modeled as a visco-hyperelastic soft matter. The Arruda–Boyce constitutive equation and the two-term Prony series are identified as the most suitable models for describing the hyperelastic and viscous components, respectively, of the ZP’s mechanical response. Material properties are identified via inverse analysis based on nonlinear optimization which fits nanoindentation curves recorded at different rates. The suitability of the proposed approach is fully demonstrated by the very good agreement between AFM data and numerically reconstructed force–indentation curves. A critical comparison of mechanical behavior of two immature ZP membranes (i.e., equine and porcine ZPs) is also carried out considering the information on the structure of these materials available from electron microscopy investigations documented in the literature.
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Affiliation(s)
- Elisa Ficarella
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, 70125 Bari, Italy; (E.F.); (M.M.); (L.S.); (E.T.); (B.T.)
| | - Mohammad Minooei
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, 70125 Bari, Italy; (E.F.); (M.M.); (L.S.); (E.T.); (B.T.)
| | - Lorenzo Santoro
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, 70125 Bari, Italy; (E.F.); (M.M.); (L.S.); (E.T.); (B.T.)
| | - Elisabetta Toma
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, 70125 Bari, Italy; (E.F.); (M.M.); (L.S.); (E.T.); (B.T.)
| | - Bartolomeo Trentadue
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, 70125 Bari, Italy; (E.F.); (M.M.); (L.S.); (E.T.); (B.T.)
| | - Marco De Spirito
- Istituto di Fisica, Università Cattolica del S. Cuore, 00168 Roma, Italy; (M.D.S.); (M.P.)
| | - Massimiliano Papi
- Istituto di Fisica, Università Cattolica del S. Cuore, 00168 Roma, Italy; (M.D.S.); (M.P.)
| | - Catalin I. Pruncu
- Department of Mechanical Engineering, Imperial College London, Exhibition Rd., London SW7 2AZ, UK
- Department of Design, Manufacturing & Engineering Management, University of Strathclyde, Glasgow G1 1XJ, UK
- Correspondence: or (C.I.P.); (L.L.)
| | - Luciano Lamberti
- Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, 70125 Bari, Italy; (E.F.); (M.M.); (L.S.); (E.T.); (B.T.)
- Correspondence: or (C.I.P.); (L.L.)
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Xia Y, Cho S, Vashisth M, Ivanovska IL, Dingal PCDP, Discher DE. Manipulating the mechanics of extracellular matrix to study effects on the nucleus and its structure. Methods 2018; 157:3-14. [PMID: 30593865 DOI: 10.1016/j.ymeth.2018.12.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 12/18/2018] [Accepted: 12/21/2018] [Indexed: 12/29/2022] Open
Abstract
Tissues such as brain, muscle, and bone differ greatly not only in their biological functions but also in their mechanical properties. Brain is far softer than muscle while bone is the stiffest tissue. Stiffness of extracellular microenvironments affects fundamental cell biological processes such as polarization and DNA replication, which affect nuclear size, shape, and levels of nuclear proteins such as the lamins that modulate gene expression. Reductionist approaches have helped dissect the effects of matrix mechanics away from confounding biochemical signals. Here, we summarize materials and methods for synthesizing and characterizing soft and stiff synthetic hydrogels widely used for mechanobiological studies. Such gels are also easily made to mimic the mechanical heterogeneity of fibrotic tissues. We further describe a nano-thin collagen fiber system, which enables control of anisotropy in addition to stiffness. With the different systems, we illustrate the effects of matrix mechanics on nuclear size, shape, and proteins including the lamins.
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Affiliation(s)
- Yuntao Xia
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physical Sciences Oncology Center at Penn, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sangkyun Cho
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physical Sciences Oncology Center at Penn, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Manasvita Vashisth
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physical Sciences Oncology Center at Penn, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Irena L Ivanovska
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physical Sciences Oncology Center at Penn, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - P C Dave P Dingal
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physical Sciences Oncology Center at Penn, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dennis E Discher
- Molecular & Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104, USA; Physical Sciences Oncology Center at Penn, University of Pennsylvania, Philadelphia, PA 19104, USA.
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3
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Deng X, Xiong F, Li X, Xiang B, Li Z, Wu X, Guo C, Li X, Li Y, Li G, Xiong W, Zeng Z. Application of atomic force microscopy in cancer research. J Nanobiotechnology 2018; 16:102. [PMID: 30538002 PMCID: PMC6288943 DOI: 10.1186/s12951-018-0428-0] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 11/24/2018] [Indexed: 12/16/2022] Open
Abstract
Atomic force microscopy (AFM) allows for nanometer-scale investigation of cells and molecules. Recent advances have enabled its application in cancer research and diagnosis. The physicochemical properties of live cells undergo changes when their physiological conditions are altered. These physicochemical properties can therefore reflect complex physiological processes occurring in cells. When cells are in the process of carcinogenesis and stimulated by external stimuli, their morphology, elasticity, and adhesion properties may change. AFM can perform surface imaging and ultrastructural observation of live cells with atomic resolution under near-physiological conditions, collecting force spectroscopy information which allows for the study of the mechanical properties of cells. For this reason, AFM has potential to be used as a tool for high resolution research into the ultrastructure and mechanical properties of tumor cells. This review describes the working principle, working mode, and technical points of atomic force microscopy, and reviews the applications and prospects of atomic force microscopy in cancer research.
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Affiliation(s)
- Xiangying Deng
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Fang Xiong
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
| | - Xiayu Li
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Bo Xiang
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Zheng Li
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Xu Wu
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Department of Chemistry, University of North Dakota, Grand Forks, ND, 58202, USA
| | - Can Guo
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
| | - Xiaoling Li
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Yong Li
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Guiyuan Li
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China
| | - Wei Xiong
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China.
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China.
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China.
| | - Zhaoyang Zeng
- The Key Laboratory of Carcinogenesis of the Chinese Ministry of Health and Hunan Key Laboratory of Translational Radiation Oncology, Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, 410013, Hunan, China.
- The Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute and School of Basic Medical Science, Xiangya School of Medicine, Central South University, Changsha, 410078, China.
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, 410013, Hunan, China.
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Abstract
Peptidoglycan is an essential component of the cell wall that protects bacteria from environmental stress. A carefully coordinated biosynthesis of peptidoglycan during cell elongation and division is required for cell viability. This biosynthesis involves sophisticated enzyme machineries that dynamically synthesize, remodel, and degrade peptidoglycan. However, when and where bacteria build peptidoglycan, and how this is coordinated with cell growth, have been long-standing questions in the field. The improvement of microscopy techniques has provided powerful approaches to study peptidoglycan biosynthesis with high spatiotemporal resolution. Recent development of molecular probes further accelerated the growth of the field, which has advanced our knowledge of peptidoglycan biosynthesis dynamics and mechanisms. Here, we review the technologies for imaging the bacterial cell wall and its biosynthesis activity. We focus on the applications of fluorescent d-amino acids, a newly developed type of probe, to visualize and study peptidoglycan synthesis and dynamics, and we provide direction for prospective research.
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Affiliation(s)
- Atanas D Radkov
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.,Current affiliation: Biophysics and Biochemistry Department, University of California, San Francisco, California 94158, USA;
| | - Yen-Pang Hsu
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, USA; , ,
| | - Garrett Booher
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, USA; , ,
| | - Michael S VanNieuwenhze
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.,Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405, USA; , ,
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Even C, Abramovici G, Delort F, Rigato AF, Bailleux V, de Sousa Moreira A, Vicart P, Rico F, Batonnet-Pichon S, Briki F. Mutation in the Core Structure of Desmin Intermediate Filaments Affects Myoblast Elasticity. Biophys J 2017; 113:627-636. [PMID: 28793217 DOI: 10.1016/j.bpj.2017.06.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 06/08/2017] [Accepted: 06/09/2017] [Indexed: 10/19/2022] Open
Abstract
Elastic properties of cells are mainly derived from the actin cytoskeleton. However, intermediate filaments are emerging as major contributors to the mechanical properties of cells. Using atomic force microscopy, we studied the elasticity of mouse myoblasts expressing a mutant form of the gene encoding for desmin intermediate filaments, p.D399Y. This variant produces desmin aggregates, the main pathological symptom of myofibrillar myopathies. Here we show that desmin-mutated cells display a 39% increased median elastic modulus compared to wild-type cells. Desmin-mutated cells required higher forces than wild-type cells to reach high indentation depths, where desmin intermediate filaments are typically located. In addition, heat-shock treatment increased the proportion of cells with aggregates and induced a secondary peak in the distribution of Young's moduli. By performing atomic force microscopy mechanical mapping combined with fluorescence microscopy, we show that higher Young's moduli were measured where desmin aggregates were located, indicating that desmin aggregates are rigid. Therefore, we provide evidence that p.D399Y stiffens mouse myoblasts. Based on these results, we suggest that p.D399Y-related myofibrillar myopathy is at least partly due to altered mechanical properties at the single-cell scale, which are propagated to the tissue scale.
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Affiliation(s)
- Catherine Even
- Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris-Saclay, Orsay, France.
| | - Gilles Abramovici
- Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris-Saclay, Orsay, France
| | - Florence Delort
- Unité de Biologie Fonctionnelle et Adaptative,UMR 8251, CNRS, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Anna F Rigato
- Bio AFM Lab, U1006, Inserm, Aix-Marseille Université, Marseille, France
| | - Virginie Bailleux
- Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris-Saclay, Orsay, France
| | - Abel de Sousa Moreira
- Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris-Saclay, Orsay, France
| | - Patrick Vicart
- Unité de Biologie Fonctionnelle et Adaptative,UMR 8251, CNRS, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Felix Rico
- Bio AFM Lab, U1006, Inserm, Aix-Marseille Université, Marseille, France
| | - Sabrina Batonnet-Pichon
- Unité de Biologie Fonctionnelle et Adaptative,UMR 8251, CNRS, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Fatma Briki
- Laboratoire de Physique des Solides, CNRS, Université Paris Sud, Université Paris-Saclay, Orsay, France.
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Guz NV, Dokukin ME, Woodworth CD, Cardin A, Sokolov I. Towards early detection of cervical cancer: Fractal dimension of AFM images of human cervical epithelial cells at different stages of progression to cancer. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2015; 11:1667-75. [PMID: 25959926 DOI: 10.1016/j.nano.2015.04.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Revised: 04/21/2015] [Accepted: 04/22/2015] [Indexed: 01/22/2023]
Abstract
UNLABELLED We used AFM HarmoniX modality to analyse the surface of individual human cervical epithelial cells at three stages of progression to cancer, normal, immortal (pre-malignant) and carcinoma cells. Primary cells from 6 normal strains, 6 cancer, and 6 immortalized lines (derived by plasmid DNA-HPV-16 transfection of cells from 6 healthy individuals) were tested. This cell model allowed for good control of the cell phenotype down to the single cell level, which is impractical to attain in clinical screening tests (ex-vivo). AFM maps of physical (nonspecific) adhesion are collected on fixed dried cells. We show that a surface parameter called fractal dimension can be used to segregate normal from both immortal pre-malignant and malignant cells with sensitivity and specificity of more than 99%. The reported method of analysis can be directly applied to cells collected in liquid cytology screening tests and identified as abnormal with regular optical methods to increase sensitivity. FROM THE CLINICAL EDITOR Despite cervical smear screening, sometimes it is very difficult to differentiate cancers cells from pre-malignant cells. By using AFM to analyze the surface properties of human cervical epithelial cells, the authors were able to accurately identify normal from abnormal cells. This method could augment existing protocols to increase diagnostic accuracy.
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Affiliation(s)
- Nataliia V Guz
- Department of Physics, Clarkson University, Potsdam, NY, USA
| | - Maxim E Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA
| | | | - Andrew Cardin
- Department of Physics, Clarkson University, Potsdam, NY, USA
| | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, MA, USA; Department of Biomedical Engineering, Tufts University, Medford, MA, USA; Department of Physics, Tufts University, Medford, MA, USA.
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Marine polysaccharide networks and diatoms at the nanometric scale. Int J Mol Sci 2013; 14:20064-78. [PMID: 24113585 PMCID: PMC3821603 DOI: 10.3390/ijms141020064] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/14/2013] [Accepted: 09/18/2013] [Indexed: 11/16/2022] Open
Abstract
Despite many advances in research on photosynthetic carbon fixation in marine diatoms, the biophysical and biochemical mechanisms of extracellular polysaccharide production remain significant challenges to be resolved at the molecular scale in order to proceed toward an understanding of their functions at the cellular level, as well as their interactions and fate in the ocean. This review covers studies of diatom extracellular polysaccharides using atomic force microscopy (AFM) imaging and the quantification of physical forces. Following a brief summary of the basic principle of the AFM experiment and the first AFM studies of diatom extracellular polymeric substance (EPS), we focus on the detection of supramolecular structures in polysaccharide systems produced by marine diatoms. Extracellular polysaccharide fibrils, attached to the diatom cell wall or released into the surrounding seawater, form distinct supramolecular assemblies best described as gel networks. AFM makes characterization of the diatom polysaccharide networks at the micro and nanometric scales and a clear distinction between the self-assembly and self-organization of these complex systems in marine environments possible.
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Dokukin M, Guz N, Sokolov I. Quantitative study of the elastic modulus of loosely attached cells in AFM indentation experiments. Biophys J 2013; 104:2123-31. [PMID: 23708352 PMCID: PMC3660635 DOI: 10.1016/j.bpj.2013.04.019] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2012] [Revised: 03/31/2013] [Accepted: 04/04/2013] [Indexed: 02/07/2023] Open
Abstract
When measuring the elastic (Young's) modulus of cells using AFM, good attachment of cells to a substrate is paramount. However, many cells cannot be firmly attached to many substrates. A loosely attached cell is more compliant under indenting. It may result in artificially low elastic modulus when analyzed with the elasticity models assuming firm attachment. Here we suggest an AFM-based method/model that can be applied to extract the correct Young's modulus of cells loosely attached to a substrate. The method is verified by using primary breast epithelial cancer cells (MCF-7) at passage 4. At this passage, approximately one-half of cells develop enough adhesion with the substrate to be firmly attached to the substrate. These cells look well spread. The other one-half of cells do not develop sufficient adhesion, and are loosely attached to the substrate. These cells look spherical. When processing the AFM indentation data, a straightforward use of the Hertz model results in a substantial difference of the Young's modulus between these two types of cells. If we use the model presented here, we see no statistical difference between the values of the Young's modulus of both poorly attached (round) and firmly attached (close to flat) cells. In addition, the presented model allows obtaining parameters of the brush surrounding the cells. The cellular brush observed is also statistically identical for both types of cells. The method described here can be applied to study mechanics of many other types of cells loosely attached to substrates, e.g., blood cells, some stem cells, cancerous cells, etc.
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Affiliation(s)
- Maxim E. Dokukin
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts
- Department of Physics, Clarkson University, Potsdam, New York
| | - Nataliia V. Guz
- Department of Physics, Clarkson University, Potsdam, New York
| | - Igor Sokolov
- Department of Mechanical Engineering, Tufts University, Medford, Massachusetts
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts
- Department of Physics, Clarkson University, Potsdam, New York
- Nanoengineering and Biotechnology Laboratories Center, Clarkson University, Potsdam, New York
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9
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Sanchez-Adams J, Athanasiou KA. Biomechanics of meniscus cells: regional variation and comparison to articular chondrocytes and ligament cells. Biomech Model Mechanobiol 2012; 11:1047-56. [PMID: 22231673 DOI: 10.1007/s10237-012-0372-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Accepted: 01/02/2012] [Indexed: 11/29/2022]
Abstract
Central to understanding mechanotransduction in the knee meniscus is the characterization of meniscus cell mechanics. In addition to biochemical and geometric differences, the inner and outer regions of the meniscus contain cells that are distinct in morphology and phenotype. This study investigated the regional variation in meniscus cell mechanics in comparison with articular chondrocytes and ligament cells. It was found that the meniscus contains two biomechanically distinct cell populations, with outer meniscus cells being stiffer (1.59 ± 0.19 kPa) than inner meniscus cells (1.07 ± 0.14 kPa). Additionally, it was found that both outer and inner meniscus cell stiffnesses were similar to ligament cells (1.32 ± 0.20 kPa), and articular chondrocytes showed the highest stiffness overall (2.51 ± 0.20 kPa). Comparison of compressibility characteristics of the cells showed similarities between articular chondrocytes and inner meniscus cells, as well as between outer meniscus cells and ligament cells. These results show that cellular biomechanics vary regionally in the knee meniscus and that meniscus cells are biomechanically similar to ligament cells. The mechanical properties of musculoskeletal cells determined in this study may be useful for the development of mathematical models or the design of experiments studying mechanotransduction in a variety of soft tissues.
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Darling EM, Pritchett PE, Evans BA, Superfine R, Zauscher S, Guilak F. Mechanical properties and gene expression of chondrocytes on micropatterned substrates following dedifferentiation in monolayer. Cell Mol Bioeng 2009; 2:395-404. [PMID: 20625462 DOI: 10.1007/s12195-009-0077-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Chondrocytes in articular cartilage normally exhibit high expression of collagen II and aggrecan but rapidly dedifferentiate to a fibroblastic phenotype if passaged in culture. Previous studies have suggested that the loss of chondrocyte phenotype is associated with changes in the structure of the F-actin cytoskeleton, which also controls cell mechanical properties. In this study, we examined how dedifferentiation in monolayer influences the mechanical properties of chondrocytes isolated from different zones of articular cartilage. Atomic force microscopy was used to measure the mechanical properties of superficial and middle/deep zone chondrocytes as they underwent serial passaging and subsequent growth on fibronectin-coated, micropatterned self-assembled monolayers (MSAMs) that restored a rounded cell shape in 2D culture. Chondrocytes exhibited significant increases in elastic and viscoelastic moduli with dedifferentiation in culture. These changes were only partially ameliorated by the restoration of a rounded shape on micropatterned surfaces. Furthermore, intrinsic zonal differences in cell mechanical properties were rapidly lost with passage. These findings indicate that cell mechanical properties may provide additional measures of phenotypic expression of chondrocytes as they undergo dedifferentiation and possibly redifferentiation in culture.
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Affiliation(s)
- Eric M Darling
- Department of Surgery, Duke University Medical Center, Durham, NC 27710 USA
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