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Kapustina M, Li D, Zhu J, Wall B, Weinreb V, Cheney RE. Changes in cell surface excess are coordinated with protrusion dynamics during 3D motility. Biophys J 2023; 122:3656-3677. [PMID: 37207658 PMCID: PMC10541482 DOI: 10.1016/j.bpj.2023.04.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 03/23/2023] [Accepted: 04/20/2023] [Indexed: 05/21/2023] Open
Abstract
To facilitate rapid changes in morphology without endangering cell integrity, each cell possesses a substantial amount of cell surface excess (CSE) that can be promptly deployed to cover cell extensions. CSE can be stored in different types of small surface projections such as filopodia, microvilli, and ridges, with rounded bleb-like projections being the most common and rapidly achieved form of storage. We demonstrate that, similar to rounded cells in 2D culture, rounded cells in 3D collagen contain large amounts of CSE and use it to cover developing protrusions. Upon retraction of a protrusion, the CSE this produces is stored over the cell body similar to the CSE produced by cell rounding. We present high-resolution imaging of F-actin and microtubules (MTs) for different cell lines in a 3D environment and demonstrate the correlated changes between CSE and protrusion dynamics. To coordinate CSE storage and release with protrusion formation and motility, we expect cells to have specific mechanisms for regulating CSE, and we hypothesize that MTs play a substantial role in this mechanism by reducing cell surface dynamics and stabilizing CSE. We also suggest that different effects of MT depolymerization on cell motility, such as inhibiting mesenchymal motility and enhancing amoeboid, can be explained by this role of MTs in CSE regulation.
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Affiliation(s)
- Maryna Kapustina
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
| | - Donna Li
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - James Zhu
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Brittany Wall
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Violetta Weinreb
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Richard E Cheney
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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2
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Chen R, Tang X, Zhao Y, Shen Z, Zhang M, Shen Y, Li T, Chung CHY, Zhang L, Wang J, Cui B, Fei P, Guo Y, Du S, Yao S. Single-frame deep-learning super-resolution microscopy for intracellular dynamics imaging. Nat Commun 2023; 14:2854. [PMID: 37202407 DOI: 10.1038/s41467-023-38452-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 04/28/2023] [Indexed: 05/20/2023] Open
Abstract
Single-molecule localization microscopy (SMLM) can be used to resolve subcellular structures and achieve a tenfold improvement in spatial resolution compared to that obtained by conventional fluorescence microscopy. However, the separation of single-molecule fluorescence events that requires thousands of frames dramatically increases the image acquisition time and phototoxicity, impeding the observation of instantaneous intracellular dynamics. Here we develop a deep-learning based single-frame super-resolution microscopy (SFSRM) method which utilizes a subpixel edge map and a multicomponent optimization strategy to guide the neural network to reconstruct a super-resolution image from a single frame of a diffraction-limited image. Under a tolerable signal density and an affordable signal-to-noise ratio, SFSRM enables high-fidelity live-cell imaging with spatiotemporal resolutions of 30 nm and 10 ms, allowing for prolonged monitoring of subcellular dynamics such as interplays between mitochondria and endoplasmic reticulum, the vesicle transport along microtubules, and the endosome fusion and fission. Moreover, its adaptability to different microscopes and spectra makes it a useful tool for various imaging systems.
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Affiliation(s)
- Rong Chen
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Xiao Tang
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yuxuan Zhao
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 430074, Wuhan, China
| | - Zeyu Shen
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Meng Zhang
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 430074, Wuhan, China
| | - Yusheng Shen
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Tiantian Li
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Casper Ho Yin Chung
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Lijuan Zhang
- School of Pharmaceutical Sciences, Guizhou University, 550025, Guizhou, China
| | - Ji Wang
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Binbin Cui
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Peng Fei
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 430074, Wuhan, China
| | - Yusong Guo
- Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong, China.
| | - Shengwang Du
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
- Department of Physics, The Hong Kong University of Science and Technology, Hong Kong, China.
- Department of Physics, The University of Texas at Dallas, Richardson, TX, 75080, USA.
| | - Shuhuai Yao
- Department of Chemical and Biological Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
- Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong, China.
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3
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Liu X, Wei Y, Li W, Li B, Liu L. Cytoskeleton induced the changes of microvilli and mechanical properties in living cells by atomic force microscopy. J Cell Physiol 2020; 236:3725-3733. [PMID: 33169846 DOI: 10.1002/jcp.30110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/08/2020] [Accepted: 10/05/2020] [Indexed: 01/05/2023]
Abstract
The cytoskeleton acts as a scaffold for membrane protrusion, such as microvilli. However, the relationship between the characteristics of microvilli and cytoskeleton remains poorly understood under the physiological state. To investigate the role of the cytoskeleton in regulating microvilli and cellular mechanical properties, atomic force microscopy (AFM) was used to detect the dynamic characteristics of microvillus morphology and elastic modulus of living HeLa cells. First, HeLa and MCF-7 cell lines were stained with Fluor-488-phalloidin and microtubules antibody. Then, the microvilli morphology was analyzed by high-resolution images of AFM in situ. Furthermore, changes in elastic modulus were investigated by the force curve of AFM. Fluorescence microscopy and AFM results revealed that destroyed microfilaments led to a smaller microvilli size, whereas the increase in the aggregation and number of microfilaments led to a larger microvilli size. The destruction and aggregation of microfilaments remarkably affected the mechanical properties of HeLa cells. Microtubule-related drugs induced the change of microtubule, but we failed to note significant differences in microvilli morphology and mechanical properties of cells. In summary, our results unraveled the relationship between microfilaments and the structure of microvilli and Young's modulus in living HeLa cells, which would contribute to the further understanding of the physiological function of the cytoskeleton in vivo.
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Affiliation(s)
- Xueyan Liu
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China
| | - Yuhui Wei
- Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China.,Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, China
| | - Bin Li
- Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Lin Liu
- Key Laboratory of Medicine, School of Laboratory Medicine and Life Sciences, Ministry of Education of China, Wenzhou Medical University, Wenzhou, China.,Division of Physical Biology and Bioimaging Centre, Shanghai Synchrotron Radiation Facility, CAS Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai Institute of Applied Physics, Shanghai, China.,Zhejiang Provincial Key Laboratory of Medical Genetics, Wenzhou Medical University, Wenzhou, China
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4
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Gosenca Matjaž M, Škarabot M, Gašperlin M, Janković B. Lamellar liquid crystals maintain keratinocytes' membrane fluidity: An AFM qualitative and quantitative study. Int J Pharm 2019; 572:118712. [PMID: 31593808 DOI: 10.1016/j.ijpharm.2019.118712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 09/13/2019] [Accepted: 09/16/2019] [Indexed: 01/21/2023]
Abstract
Despite extensive investigations of lamellar liquid crystals for dermal application, the effects of these systems at the cellular level are still not well elucidated. The key aim of this study was to determine the elasticity and morphological features of keratinocytes after exposure to a lamellar liquid crystal system (LLCS) using atomic force microscopy (AFM) as the method of choice. Prior to AFM assessment, a cell proliferation test and light plus fluorescence imaging were applied to determine the sub-toxic concentration of LLCS. According to the AFM results, slightly altered morphology was observed in the case of fixed keratinocytes, while an intact morphology was visualized on live cells. From the quantitative study, decreased Young's moduli were determined for fixed cells (i.e., 8.6 vs. 15.2 MPa and 1.3 vs. 2.9 MPa for ethanol or PFA-fixed LLCS-treated vs. control cells, respectively) and live cells (i.e., ranging from 0.6 to 2.8 for LLCS-treated vs. 1.1-4.5 MPa for untreated cells), clearly demonstrating increased cell elasticity. This is related to improved membrane fluidity as a consequence of interactions between the acyl chains of cell membrane phosphatidylcholine and those of LLCS. What seems to be of major importance is that the study confirms the potential clinical relevance of such systems in treatment of aged skin with characteristically more rigid epithelial cells.
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Affiliation(s)
- Mirjam Gosenca Matjaž
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, Ljubljana, Slovenia
| | - Miha Škarabot
- Jožef Stefan Institute, Department of Condensed Matter Physics, Jamova cesta 39, Ljubljana, Slovenia
| | - Mirjana Gašperlin
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, Ljubljana, Slovenia
| | - Biljana Janković
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, Ljubljana, Slovenia.
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5
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Merkher Y, Alvarez-Elizondo MB, Weihs D. Taxol reduces synergistic, mechanobiological invasiveness of metastatic cells. CONVERGENT SCIENCE PHYSICAL ONCOLOGY 2017. [DOI: 10.1088/2057-1739/aa8c0b] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Gefen A, Weihs D. Cytoskeleton and plasma-membrane damage resulting from exposure to sustained deformations: A review of the mechanobiology of chronic wounds. Med Eng Phys 2016; 38:828-33. [DOI: 10.1016/j.medengphy.2016.05.014] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2016] [Revised: 05/19/2016] [Accepted: 05/23/2016] [Indexed: 12/14/2022]
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7
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Gefen A, Weihs D. Mechanical cytoprotection: A review of cytoskeleton-protection approaches for cells. J Biomech 2016; 49:1321-1329. [DOI: 10.1016/j.jbiomech.2015.10.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Revised: 10/20/2015] [Accepted: 10/21/2015] [Indexed: 12/28/2022]
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8
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Park K, Mehrnezhad A, Corbin EA, Bashir R. Optomechanical measurement of the stiffness of single adherent cells. LAB ON A CHIP 2015; 15:3460-4. [PMID: 26220705 PMCID: PMC5841955 DOI: 10.1039/c5lc00444f] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recent advances in mechanobiology have accumulated strong evidence showing close correlations between the physiological conditions and mechanical properties of cells. In this paper, a novel optomechanical technique to characterize the stiffness of single adherent cells attached on a substrate is reported. The oscillation in a cell's height on a vertically vibrating reflective substrate is measured with a laser Doppler vibrometer as apparent changes in the phase of the measured velocity. This apparent phase shift and the height oscillation are shown to be affected by the mechanical properties of human colorectal adenocarcinoma cells (HT-29). The reported optomechanical technique can provide high-throughput stiffness measurement of single adherent cells over time with minimal perturbation.
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Affiliation(s)
- Kidong Park
- Division of Electrical and Computer Engineering, Louisiana State University, Baton Rouge, LA 70803, USA.
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9
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Yallapu MM, Katti KS, Katti DR, Mishra SR, Khan S, Jaggi M, Chauhan SC. The roles of cellular nanomechanics in cancer. Med Res Rev 2014; 35:198-223. [PMID: 25137233 DOI: 10.1002/med.21329] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The biomechanical properties of cells and tissues may be instrumental in increasing our understanding of cellular behavior and cellular manifestations of diseases such as cancer. Nanomechanical properties can offer clinical translation of therapies beyond what are currently employed. Nanomechanical properties, often measured by nanoindentation methods using atomic force microscopy, may identify morphological variations, cellular binding forces, and surface adhesion behaviors that efficiently differentiate normal cells and cancer cells. The aim of this review is to examine current research involving the general use of atomic force microscopy/nanoindentation in measuring cellular nanomechanics; various factors and instrumental conditions that influence the nanomechanical properties of cells; and implementation of nanoindentation methods to distinguish cancer cells from normal cells or tissues. Applying these fundamental nanomechanical properties to current discoveries in clinical treatment may result in greater efficiency in diagnosis, treatment, and prevention of cancer, which ultimately can change the lives of patients.
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Affiliation(s)
- Murali M Yallapu
- Department of Pharmaceutical Sciences and Center for Cancer Research, College of Pharmacy, University of Tennessee Health Science Center, Memphis, Tennessee, 38163
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10
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Krisenko MO, Cartagena A, Raman A, Geahlen RL. Nanomechanical property maps of breast cancer cells as determined by multiharmonic atomic force microscopy reveal Syk-dependent changes in microtubule stability mediated by MAP1B. Biochemistry 2014; 54:60-8. [PMID: 24914616 PMCID: PMC4295795 DOI: 10.1021/bi500325n] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
![]()
The
Syk protein-tyrosine kinase, a well-characterized modulator
of immune recognition receptor signaling, also plays important, but
poorly characterized, roles in tumor progression, acting as an inhibitor
of cellular motility and metastasis in highly invasive cancer cells.
Multiharmonic
atomic force microscopy (AFM) was used to map nanomechanical properties
of live MDA-MB-231 breast cancer cells either lacking or expressing
Syk. The expression of Syk dramatically altered the cellular topography,
reduced cell height, increased elasticity, increased viscosity, and
allowed visualization of a more substantial microtubule network. The
microtubules of Syk-expressing cells were more stable to nocodazole-induced
depolymerization and were more highly acetylated than those of Syk-deficient
cells. Silencing of MAP1B, a major substrate for Syk in MDA-MB-231
cells, attenuated Syk-dependent microtubule stability and reversed
much of the effect of Syk on cellular topography, stiffness, and viscosity.
This study illustrates the use of multiharmonic AFM both to quantitatively
map the local nanomechanical properties
of living cells and to identify the underlying mechanisms by which
these properties are modulated by signal transduction machinery.
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Affiliation(s)
- Mariya O Krisenko
- Department of Medicinal Chemistry and Molecular Pharmacology, ‡School of Mechanical Engineering, §Purdue Center for Cancer Research, and ∥Birck Nanotechnology Center, Purdue University , West Lafayette, Indiana 47907, United States
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11
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Ogneva IV, Buravkov SV, Shubenkov AN, Buravkova LB. Mechanical characteristics of mesenchymal stem cells under impact of silica-based nanoparticles. NANOSCALE RESEARCH LETTERS 2014; 9:284. [PMID: 24948901 PMCID: PMC4055799 DOI: 10.1186/1556-276x-9-284] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 05/24/2014] [Indexed: 05/07/2023]
Abstract
Silica-based nanoparticles (NPs) pose great potential for medical and biological applications; however, their interactions with living cells have not been investigated in full. The objective of this study was to analyze the mechanical characteristics of mesenchymal stem cells when cultured in the presence of silica (Si) and silica-boron (SiB) nanoparticles. Cell stiffness was measured using atomic force microscopy; F-actin structure was evaluated using TRITC-phalloidin by confocal microscopy. The obtained data suggested that the cell stiffness increased within the following line: 'Control' - 'Si' - 'SiB' (either after 1-h cultivation or 24-h incubation). Moreover, the cell stiffness was found to be higher after 1-h cultivation as compared to 24-h cultivation. This result shows that there is a two-phase process of particle diffusion into cells and that the particles interact directly with the membrane and, further, with the submembranous cytoskeleton. Conversely, the intensity of phalloidin fluorescence dropped within the same line: Control - Si - SiB. It could be suggested that the effects of silica-based particles may result in structural reorganization of cortical cytoskeleton with subsequent stiffness increase and concomitant F-actin content decrease (for example, in recruitment of additional actin-binding proteins within membrane and regrouping of actin filaments).
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Affiliation(s)
- Irina V Ogneva
- Department of Molecular and Cell Biomedicine, State Scientific Center of Russian Federation Institute of Biomedical Problems of the Russian Academy of Sciences, Khoroshevskoyoe shosse, 76a, Moscow 123007, Russia
- I.M. Sechenov First Moscow State Medical University, Moscow 119991, Russia
| | - Sergey V Buravkov
- Faculty of Fundamental Medicine, Lomonosov Moscow State University, Moscow 119192, Russia
| | - Alexander N Shubenkov
- Department of Molecular and Cell Biomedicine, State Scientific Center of Russian Federation Institute of Biomedical Problems of the Russian Academy of Sciences, Khoroshevskoyoe shosse, 76a, Moscow 123007, Russia
| | - Ludmila B Buravkova
- Department of Molecular and Cell Biomedicine, State Scientific Center of Russian Federation Institute of Biomedical Problems of the Russian Academy of Sciences, Khoroshevskoyoe shosse, 76a, Moscow 123007, Russia
- Faculty of Fundamental Medicine, Lomonosov Moscow State University, Moscow 119192, Russia
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12
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Xia P, Zhou J, Song X, Wu B, Liu X, Li D, Zhang S, Wang Z, Yu H, Ward T, Zhang J, Li Y, Wang X, Chen Y, Guo Z, Yao X. Aurora A orchestrates entosis by regulating a dynamic MCAK-TIP150 interaction. J Mol Cell Biol 2014; 6:240-54. [PMID: 24847103 DOI: 10.1093/jmcb/mju016] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Entosis, a cell-in-cell process, has been implicated in the formation of aneuploidy associated with an aberrant cell division control. Microtubule plus-end-tracking protein TIP150 facilitates the loading of MCAK onto the microtubule plus ends and orchestrates microtubule plus-end dynamics during cell division. Here we show that TIP150 cooperates with MCAK to govern entosis via a regulatory circuitry that involves Aurora A-mediated phosphorylation of MCAK. Our biochemical analyses show that MCAK forms an intra-molecular association, which is essential for TIP150 binding. Interestingly, Aurora A-mediated phosphorylation of MCAK modulates its intra-molecular association, which perturbs the MCAK-TIP150 interaction in vitro and inhibits entosis in vivo. To probe if MCAK-TIP150 interaction regulates microtubule plasticity to affect the mechanical properties of cells during entosis, we used an optical trap to measure the mechanical rigidity of live MCF7 cells. We find that the MCAK cooperates with TIP150 to promote microtubule dynamics and modulate the mechanical rigidity of the cells during entosis. Our results show that a dynamic interaction of MCAK-TIP150 orchestrated by Aurora A-mediated phosphorylation governs entosis via regulating microtubule plus-end dynamics and cell rigidity. These data reveal a previously unknown mechanism of Aurora A regulation in the control of microtubule plasticity during cell-in-cell processes.
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Affiliation(s)
- Peng Xia
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Jinhua Zhou
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Xiaoyu Song
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Bing Wu
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Xing Liu
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China Molecular Imaging Center, Atlanta Clinical and Translational Science Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Di Li
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Shuyuan Zhang
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Zhikai Wang
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China Molecular Imaging Center, Atlanta Clinical and Translational Science Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Huijuan Yu
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | - Tarsha Ward
- Molecular Imaging Center, Atlanta Clinical and Translational Science Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA Harvard Medical School, Boston, MA 02115, USA
| | - Jiancun Zhang
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China Guangzhou Institutes of Biomedicine and Health, Guangzhou 510513, China
| | - Yinmei Li
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
| | | | - Yong Chen
- Xijing Hospital, The Fourth Military Medical University, Xi'an 710032, China
| | - Zhen Guo
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China Molecular Imaging Center, Atlanta Clinical and Translational Science Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Xuebiao Yao
- Anhui Key Laboratory of Cellular Dynamics & Chemical Biology, Department of Optics and Optical Engineering, and Hefei National Laboratory for Physical Sciences at Nanoscale, University of Science and Technology of China, Hefei 230027, China
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13
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Microtubules mediate changes in membrane cortical elasticity during contractile activation. Exp Cell Res 2014; 322:21-9. [DOI: 10.1016/j.yexcr.2013.12.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 12/17/2013] [Accepted: 12/31/2013] [Indexed: 12/20/2022]
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14
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Yoo L, Reed J, Shin A, Demer JL. Atomic force microscopy determination of Young׳s modulus of bovine extra-ocular tendon fiber bundles. J Biomech 2014; 47:1899-903. [PMID: 24767704 DOI: 10.1016/j.jbiomech.2014.02.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 12/30/2013] [Accepted: 02/06/2014] [Indexed: 12/29/2022]
Abstract
Extra-ocular tendons (EOTs) transmit the oculorotary force of the muscles to the eyeball to generate dynamic eye movements and align the eyes, yet the mechanical properties of the EOTs remain undefined. The EOTs are known to be composed of parallel bundles of small fibers whose mechanical properties must be determined in order to characterize the overall behavior of EOTs. The current study aimed to investigate the transverse Young׳s modulus of EOT fiber bundles using atomic force microscopy (AFM). Fresh bovine EOT fiber bundle specimens were maintained under temperature and humidity control, and indented 100nm by the inverted pyramid tip of an AFM (Veeco Digital Instruments, NY). Ten indentations were conducted for each of 3 different locations of 10 different specimens from each of 6 EOTs, comprising a total of 1800 indentations. Young׳s modulus for each EOT was determined using a Hertzian contact model. Young׳s moduli for fiber bundles from all six EOTs were determined. Mean Young׳s moduli for fiber bundles were similar for the six anatomical EOTs: lateral rectus 60.12±2.69 (±SD)MPa, inferior rectus 59.69±5.34MPa, medial rectus 56.92±1.91MPa, superior rectus 59.66±2.64MPa, inferior oblique 57.7±1.36MPa, and superior oblique 59.15±2.03. Variation in Young׳s moduli among the six EOTs was not significant (P>0.25). The Young׳s modulus of bovine EOT fibers is highly uniform among the six extraocular muscles, suggesting that each EOT is assembled from fiber bundles representing the same biomechanical elements. This uniformity will simplify overall modeling.
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Affiliation(s)
- Lawrence Yoo
- Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, CA 90095-7002, USA
| | - Jason Reed
- Department of Physics, Virginia Commonwealth University, Richmond, VA, USA
| | - Andrew Shin
- Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, CA 90095-7002, USA; Department of Mechanical Engineering, University of California, Los Angeles, CA, USA
| | - Joseph L Demer
- Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, CA 90095-7002, USA; Biomedical Engineering Interdepartmental Program, University of California, Los Angeles, CA, USA; Neuroscience Interdepartmental Program, University of California, Los Angeles, CA, USA; Department of Neurology, University of California, Los Angeles, CA, USA.
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15
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Ramos JR, Pabijan J, Garcia R, Lekka M. The softening of human bladder cancer cells happens at an early stage of the malignancy process. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2014; 5:447-57. [PMID: 24778971 PMCID: PMC3999871 DOI: 10.3762/bjnano.5.52] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Accepted: 03/11/2014] [Indexed: 05/20/2023]
Abstract
Various studies have demonstrated that alterations in the deformability of cancerous cells are strongly linked to the actin cytoskeleton. By using atomic force microscopy (AFM), it is possible to determine such changes in a quantitative way in order to distinguish cancerous from non-malignant cells. In the work presented here, the elastic properties of human bladder cells were determined by means of AFM. The measurements show that non-malignant bladder HCV29 cells are stiffer (higher Young's modulus) than cancerous cells (HTB-9, HT1376, and T24 cell lines). However, independently of the histological grade of the studied bladder cancer cells, all cancerous cells possess a similar level of the deformability of about a few kilopascals, significantly lower than non-malignant cells. This underlines the diagnostic character of stiffness that can be used as a biomarker of bladder cancer. Similar stiffness levels, observed for cancerous cells, cannot be fully explained by the organization of the actin cytoskeleton since it is different in all malignant cells. Our results underline that it is neither the spatial organization of the actin filaments nor the presence of stress fibers, but the overall density and their 3D-organization in a probing volume play the dominant role in controlling the elastic response of the cancerous cell to an external force.
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Affiliation(s)
- Jorge R Ramos
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
- Centro de Estudios Avanzados de Cuba, Carretera de San Antonio de los Baños, km 1 ½, Valle Grande, La Habana, Cuba
| | - Joanna Pabijan
- The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland
| | - Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3, 28049 Madrid, Spain
| | - Malgorzata Lekka
- The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, Radzikowskiego 152, 31-342 Kraków, Poland
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16
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Wilhelm KR, Roan E, Ghosh MC, Parthasarathi K, Waters CM. Hyperoxia increases the elastic modulus of alveolar epithelial cells through Rho kinase. FEBS J 2013; 281:957-69. [PMID: 24289040 DOI: 10.1111/febs.12661] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 11/05/2013] [Accepted: 11/26/2013] [Indexed: 12/31/2022]
Abstract
Patients with acute lung injury are administered high concentrations of oxygen during mechanical ventilation, and while both hyperoxia and mechanical ventilation are necessary, each can independently cause additional injury. However, the precise mechanisms that lead to injury are not well understood. We hypothesized that alveolar epithelial cells may be more susceptible to injury caused by mechanical ventilation because hyperoxia causes cells to be stiffer due to increased filamentous actin (f-actin) formation via the GTPase RhoA and its effecter Rho kinase (ROCK). We examined cytoskeletal structures in cultured murine lung alveolar epithelial cells (MLE-12) under normoxic and hyperoxic (48 h) conditions. We also measured cell elasticity (E) using an atomic force microscope in the indenter mode. Hyperoxia caused increased f-actin stress fibers and bundle formation, an increase in g- and f-actin, an increase in nuclear area and a decrease in nuclear height, and cells became stiffer (higher E). Treatment with an inhibitor (Y-27632) of ROCK significantly decreased E and prevented the cytoskeletal changes, while it did not influence the nuclear height and area. Pre-exposure of cells to hyperoxia promoted detachment when cells were subsequently stretched cyclically, but the ROCK inhibitor prevented this effect. Hyperoxia caused thickening of vinculin focal adhesion plaques, and inhibition of ROCK reduced the formation of distinct focal adhesion plaques. Phosphorylation of focal adhesion kinase was significantly reduced by both hyperoxia and treatment with Y-27632. Hyperoxia caused increased cell stiffness and promoted cell detachment during stretch. These effects were ameliorated by inhibition of ROCK.
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Affiliation(s)
- Kristina R Wilhelm
- Department of Physiology, University of Tennessee Health Science Center, Memphis, TN, USA
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17
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Chiou YW, Lin HK, Tang MJ, Lin HH, Yeh ML. The influence of physical and physiological cues on atomic force microscopy-based cell stiffness assessment. PLoS One 2013; 8:e77384. [PMID: 24194882 PMCID: PMC3806741 DOI: 10.1371/journal.pone.0077384] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 09/04/2013] [Indexed: 01/16/2023] Open
Abstract
Atomic force microscopy provides a novel technique for differentiating the mechanical properties of various cell types. Cell elasticity is abundantly used to represent the structural strength of cells in different conditions. In this study, we are interested in whether physical or physiological cues affect cell elasticity in Atomic force microscopy (AFM)-based assessments. The physical cues include the geometry of the AFM tips, the indenting force and the operating temperature of the AFM. All of these cues show a significant influence on the cell elasticity assessment. Sharp AFM tips create a two-fold increase in the value of the effective Young's modulus (E(eff)) relative to that of the blunt tips. Higher indenting force at the same loading rate generates higher estimated cell elasticity. Increasing the operation temperature of the AFM leads to decreases in the cell stiffness because the structure of actin filaments becomes disorganized. The physiological cues include the presence of fetal bovine serum or extracellular matrix-coated surfaces, the culture passage number, and the culture density. Both fetal bovine serum and the extracellular matrix are critical for cells to maintain the integrity of actin filaments and consequently exhibit higher elasticity. Unlike primary cells, mouse kidney progenitor cells can be passaged and maintain their morphology and elasticity for a very long period without a senescence phenotype. Finally, cell elasticity increases with increasing culture density only in MDCK epithelial cells. In summary, for researchers who use AFM to assess cell elasticity, our results provide basic and significant information about the suitable selection of physical and physiological cues.
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Affiliation(s)
- Yu-Wei Chiou
- Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan
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18
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Biological Water Dynamics and Entropy: A Biophysical Origin of Cancer and Other Diseases. ENTROPY 2013. [DOI: 10.3390/e15093822] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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19
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Actin-based biomechanical features of suspended normal and cancer cells. J Biosci Bioeng 2013; 116:380-5. [PMID: 23567154 DOI: 10.1016/j.jbiosc.2013.03.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 03/04/2013] [Accepted: 03/05/2013] [Indexed: 11/20/2022]
Abstract
The mechanical features of individual cells have been regarded as unique indicators of their states, which could constantly change in accordance with cellular events and diseases. Particularly, cancer progression was characterized by the disruption and/or reorganization of actin filaments causing mechanical changes. Thus, mechanical characterization of cells could become an effective cytotechnological approach for early detection of cancer. To develop mechanical cytotechnology, it would be necessary to clarify the mechanical properties in various cell adhesion states. In this study, we investigated the surface mechanical behavior of cancer and normal cells in the adherent and suspended states using atomic force microscopy. Adherent normal stromal cells showed high surface stiffness due to developed actin cap structures on their apical surface, whereas cancer cells did not have developed filamentous actin structures, and their surface stiffness was low. Upon cell detachment from the substrate, filamentous actin structures of adherent normal stromal cells reorganized to the cortical region and their surface stiffness decreased consequently however, the stiffness of suspended normal cells remained higher than that of cancer cells. These suspended state actin structures were similar, regardless of the cell type. Furthermore, the mechanical responses of the cancer and normal stromal cells to perturbation of the actin cytoskeleton were different, suggesting distinct regulatory mechanisms for actin cytoskeleton in cancer and normal cells in both adherent and suspended states. Therefore, cancer cells possess specific mechanical and actin cytoskeleton features different from normal stromal cells.
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20
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Intracellular mechanics and activity of breast cancer cells correlate with metastatic potential. Cell Biochem Biophys 2012; 63:199-209. [PMID: 22555560 DOI: 10.1007/s12013-012-9356-z] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Mechanics of cancer cells are directly linked to their metastatic potential, or ability to produce a secondary tumor at a distant site. Metastatic cells survive in the circulatory system in a non-adherent state, and can squeeze through barriers in the body. Such considerable structural changes in cells rely on rapid remodeling of internal structure and mechanics. While external mechanical measurements have demonstrated enhanced pliability of cancer cells with increased metastatic potential, little is known about dynamics of their interior and we expect that to change significantly in metastatic cells. We perform a comparative study, using particle-tracking to evaluate the intracellular mechanics of living epithelial breast cells with varying invasiveness. Particles in all examined cell lines exhibit super-diffusion with a scaling exponent of 1.4 at short lag times, likely related to active transport by fluctuating microtubules and their associated molecular motors. Specifics of probe-particle transport differ between the cell types, depending on the cytoskeleton network-structure and interactions with it. Our study shows that the internal microenvironment of the highly metastatic cells evaluated here is more pliable and their cytoskeleton is less dense than the poorly metastatic and benign cells. We thus reveal intracellular structure and mechanics that can support the unique function and invasive capabilities of highly metastatic cells.
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21
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Guolla L, Bertrand M, Haase K, Pelling AE. Force transduction and strain dynamics in actin stress fibres in response to nanonewton forces. J Cell Sci 2012; 125:603-13. [PMID: 22389400 DOI: 10.1242/jcs.088302] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
It is becoming clear that mechanical stimuli are crucial factors in regulating the biology of the cell, but the short-term structural response of a cell to mechanical forces remains relatively poorly understood. We mechanically stimulated cells transiently expressing actin-EGFP with controlled forces (0-20 nN) in order to investigate the structural response of the cell. Two clear force-dependent responses were observed: a short-term (seconds) local deformation of actin stress fibres and a long-term (minutes) force-induced remodelling of stress fibres at cell edges, far from the point of contact. By photobleaching markers along stress fibres we were also able to quantify strain dynamics occurring along the fibres throughout the cell. The results reveal that the cell exhibits complex heterogeneous negative and positive strain fluctuations along stress fibres in resting cells that indicate localized contraction and stretch dynamics. The application of mechanical force results in the activation of myosin contractile activity reflected in an ~50% increase in strain fluctuations. This approach has allowed us to directly observe the activation of myosin in response to mechanical force and the effects of cytoskeletal crosslinking on local deformation and strain dynamics. The results demonstrate that force application does not result in simplistic isotropic deformation of the cytoarchitecture, but rather a complex and localized response that is highly dependent on an intact microtubule network. Direct visualization of force-propagation and stress fibre strain dynamics have revealed several crucial phenomena that take place and ultimately govern the downstream response of a cell to a mechanical stimulus.
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Affiliation(s)
- Louise Guolla
- Department of Physics, MacDonald Hall, 150 Louis Pasteur, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
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22
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Roan E, Wilhelm K, Bada A, Makena PS, Gorantla VK, Sinclair SE, Waters CM. Hyperoxia alters the mechanical properties of alveolar epithelial cells. Am J Physiol Lung Cell Mol Physiol 2012; 302:L1235-41. [PMID: 22467640 DOI: 10.1152/ajplung.00223.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Patients with severe acute lung injury are frequently administered high concentrations of oxygen (>50%) during mechanical ventilation. Long-term exposure to high levels of oxygen can cause lung injury in the absence of mechanical ventilation, but the combination of the two accelerates and increases injury. Hyperoxia causes injury to cells through the generation of excessive reactive oxygen species. However, the precise mechanisms that lead to epithelial injury and the reasons for increased injury caused by mechanical ventilation are not well understood. We hypothesized that alveolar epithelial cells (AECs) may be more susceptible to injury caused by mechanical ventilation if hyperoxia alters the mechanical properties of the cells causing them to resist deformation. To test this hypothesis, we used atomic force microscopy in the indentation mode to measure the mechanical properties of cultured AECs. Exposure of AECs to hyperoxia for 24 to 48 h caused a significant increase in the elastic modulus (a measure of resistance to deformation) of both primary rat type II AECs and a cell line of mouse AECs (MLE-12). Hyperoxia also caused remodeling of both actin and microtubules. The increase in elastic modulus was blocked by treatment with cytochalasin D. Using finite element analysis, we showed that the increase in elastic modulus can lead to increased stress near the cell perimeter in the presence of stretch. We then demonstrated that cyclic stretch of hyperoxia-treated cells caused significant cell detachment. Our results suggest that exposure to hyperoxia causes structural remodeling of AECs that leads to decreased cell deformability.
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23
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Ketene AN, Roberts PC, Shea AA, Schmelz EM, Agah M. Actin filaments play a primary role for structural integrity and viscoelastic response in cells. Integr Biol (Camb) 2012; 4:540-9. [DOI: 10.1039/c2ib00168c] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Alperen N. Ketene
- Department of Mechanical Engineering, 100 Randolph Hall, Blacksburg, VA, USA. Fax: +1-540-231-3362; Tel: +1-540-231-4180
| | - Paul C. Roberts
- Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Corporate Research Center, Building 23 (ILSB), 1981 Kraft Drive (0913), Blacksburg, VA 24061, USA. Fax: +1-540-231-3414; Tel: +1-540-231-7949
| | - Amanda A. Shea
- Department of Human Nutrition Food & Exercise, Corporate Research Center, Building 23 (ILSB) 1981 Kraft Drive (0913), Blacksburg, VA 24061, USA. Fax: +1-540-231-5522; Tel: +1-540-231-0099
| | - Eva M. Schmelz
- Department of Human Nutrition Food & Exercise, Corporate Research Center, Building 23 (ILSB) 1981 Kraft Drive, Blacksburg, VA 24061, USA. Fax: +1-540-231-5522; Tel: +1-540-231-3649
| | - Masoud Agah
- VT MEMS Laboratory, The Bradley Department of Electrical and Computer Engineering, 469 Whittemore Hall, Blacksburg, VA 24061, USA. Fax: +1-540-231-3362; Tel: +1-540-231-2653
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24
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The effects of cancer progression on the viscoelasticity of ovarian cell cytoskeleton structures. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2012; 8:93-102. [DOI: 10.1016/j.nano.2011.05.012] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 04/13/2011] [Accepted: 05/19/2011] [Indexed: 01/17/2023]
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25
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26
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Zhou ZL, Ngan AHW, Tang B, Wang AX. Reliable measurement of elastic modulus of cells by nanoindentation in an atomic force microscope. J Mech Behav Biomed Mater 2011; 8:134-42. [PMID: 22402160 DOI: 10.1016/j.jmbbm.2011.11.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 11/04/2011] [Accepted: 11/07/2011] [Indexed: 01/02/2023]
Abstract
The elastic modulus of an oral cancer cell line UM1 is investigated by nanoindentation in an atomic force microscope with a flat-ended tip. The commonly used Hertzian method gives apparent elastic modulus which increases with the loading rate, indicating strong effects of viscoelasticity. On the contrary, a rate-jump method developed for viscoelastic materials gives elastic modulus values which are independent of the rate-jump magnitude. The results show that the rate-jump method can be used as a standard protocol for measuring elastic stiffness of living cells, since the measured values are intrinsic properties of the cells.
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Affiliation(s)
- Z L Zhou
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China
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27
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Ho QP, Wang SL, Wang MJ. Creation of biofunctionalized micropatterns on poly(methyl methacrylate) by single-step phase separation method. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4496-4503. [PMID: 22022975 DOI: 10.1021/am201188x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this study, the polymer thin films containing micropatterns and biological functionalities were created by one-step procedure. The adjustable compositions among poly(methyl methacrylate) (PMMA), solvents, nonsolvent, and additional macromolecules formed the polymer thin films with different diameters ranging from 5 to 37 μm. The influences of topographical and chemical cues were investigated by directly cultivating L-929 fibroblasts on the prepared samples. The results revealed the predominant effect of surface topography that the cell density of L-929 fibroblasts increased proportionally with the average diameter of microconcaves. The cell number raised significantly on the PMMA thin films containing type I collagen and dopamine, with or without microstructures. On the other hand, the addition of bovine serum albumin in PMMA limited the growth of cells. The surface chemical composition and cell responses were evaluated by electron spectroscopy for chemical analysis (ESCA), viability assay, and immunostaining, respectively. This work proposed a simple and effective approach to incorporate the biological functions and surface topography simultaneously onto surface of materials that provided further applications for biomedical materials.
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Affiliation(s)
- Quoc-Phong Ho
- Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan
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28
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Prandi S, Sala GL, Bellocci M, Alessandrini A, Facci P, Bigiani A, Rossini GP. Palytoxin induces cell lysis by priming a two-step process in mcf-7 cells. Chem Res Toxicol 2011; 24:1283-96. [PMID: 21728342 DOI: 10.1021/tx2001866] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The cytolytic action of palytoxin (PlTX) was recognized long ago, but its features have remained largely undetermined. We used biochemical, morphological, physiological, and physical tools, to study the cytolytic response in MCF-7 cells, as our model system. Cytolysis represented a stereotyped response induced by the addition of isotonic phosphate buffer (PBS) to cells that had been exposed to PlTX, after toxin removal and under optimal and suboptimal experimental conditions. Cytolysis was sensitive to osmolytes present during cell exposure to PlTX but not in the course of the lytic phase. Fluorescence microscopy showed that PlTX caused cell rounding and rearrangement of the actin cytoskeleton. Atomic force microscopy (AFM) was used to monitor PlTX effects in real time, and we found that morphological and mechanical properties of MCF-7 cells did not change during toxin exposure, but increased cell height and decreased stiffness at its surface were observed when PBS was added to PlTX-treated cells. The presence of an osmolyte during PlTX treatment prevented the detection of changes in morphological and mechanical properties caused by PBS addition to toxin-treated cells, as detected by AFM. By patch-clamp technique, we confirmed that PlTX action involved the transformation of the Na(+),K(+)-ATPase into a channel and found that cell membrane capacitance was not changed by PlTX, indicating that the membrane surface area was not greatly affected in our model system. Overall, our findings show that the cytolytic response triggered by PlTX in MCF-7 cells includes a first phase, which is toxin-dependent and osmolyte-sensitive, priming cells to lytic events taking place in a separate phase, which does not require the presence of the toxin and is osmolyte-insensitive but is accompanied by marked reorganization of actin-based cytoskeleton and altered mechanical properties at the cell's surface. A model of the two-step process of PlTX-induced cytolysis is presented.
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Affiliation(s)
- Simone Prandi
- Dipartimento di Scienze Biomediche, Università di Modena e Reggio Emilia , Via Campi 287, I-41125 Modena, Italy
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29
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Jackson VC, Dewilde S, Albo AG, Lis K, Corpillo D, Canepa B. The activity of aminoacyl-tRNA synthetase-interacting multi-functional protein 1 (AIMP1) on endothelial cells is mediated by the assembly of a cytoskeletal protein complex. J Cell Biochem 2011; 112:1857-68. [DOI: 10.1002/jcb.23104] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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30
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The nanomechanical properties of rat fibroblasts are modulated by interfering with the vimentin intermediate filament system. J Struct Biol 2011; 174:476-84. [DOI: 10.1016/j.jsb.2011.03.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/05/2011] [Accepted: 03/15/2011] [Indexed: 11/20/2022]
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31
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Cross SE, Jin YS, Lu QY, Rao J, Gimzewski JK. Green tea extract selectively targets nanomechanics of live metastatic cancer cells. NANOTECHNOLOGY 2011; 22:215101. [PMID: 21451222 PMCID: PMC3151463 DOI: 10.1088/0957-4484/22/21/215101] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Green tea extract (GTE) is known to be a potential anticancer agent (Yang et al 2009 Nat. Rev. Cancer 9 429-39) with various biological activities (Lu et al 2005 Clin. Cancer Res. 11 1675-83; Yang et al 1998 Carcinogenesis 19 611-6) yet the precise mechanism of action is still unclear. The biomechanical response of GTE treated cells taken directly from patient's body samples was measured using atomic force microscopy (AFM) (Binnig et al 1986 Phys. Rev. Lett. 56 930). We found significant increase in stiffness of GTE treated metastatic tumor cells, with a resulting value similar to untreated normal mesothelial cells, whereas mesothelial cell stiffness after GTE treatment is unchanged. Immunofluorescence analysis showed an increase in cytoskeletal-F-actin in GTE treated tumor cells, suggesting GTE treated tumor cells display mechanical, structural and morphological features similar to normal cells, which appears to be mediated by annexin-I expression, as determined by siRNA analysis of an in vitro cell line model. Our data indicates that GTE selectively targets human metastatic cancer cells but not normal mesothelial cells, a finding that is significantly advantageous compared to conventional chemotherapy agents.
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Affiliation(s)
- Sarah E. Cross
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
| | - Yu-Sheng Jin
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA 90095, USA
| | - Qing-Yi Lu
- Department of Medicine, Center for Human Nutrition, University of California, Los Angeles, CA 90095, USA
| | - JianYu Rao
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, CA 90095, USA
| | - James K. Gimzewski
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
- International Center for Materials Nanoarchitectonics Satellite (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan
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32
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Contractility dominates adhesive ligand density in regulating cellular de-adhesion and retraction kinetics. Ann Biomed Eng 2010; 39:1163-73. [PMID: 21046466 PMCID: PMC3069333 DOI: 10.1007/s10439-010-0195-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Accepted: 10/17/2010] [Indexed: 01/09/2023]
Abstract
Cells that are enzymatically detached from a solid substrate rapidly round up as the tensile prestress in the cytoskeleton is suddenly unopposed by cell-ECM adhesions. We recently showed that this retraction follows sigmoidal kinetics with time constants that correlate closely with cortical stiffness values. This raises the promising prospect that these de-adhesion measurements may be used for high-throughput screening of cell mechanical properties; however, an important limitation to doing so is the possibility that the retraction kinetics may also be influenced and potentially rate-limited by the time needed to sever matrix adhesions. In this study, we address this open question by separating contributions of contractility and adhesion to cellular de-adhesion and retraction kinetics. We first develop serum-free conditions under which U373 MG glioma cells can be cultured on substrates of fixed fibronectin density without direct matrix contributions from the medium. We show that while spreading area increases with ECM protein density, cortical stiffness and the time constants of retraction do not. Conversely, addition of lysophosphatidic acid (LPA) to stimulate cell contractility strongly speeds retraction, independent of the initial matrix protein density and LPA's contributions to spreading area. All of these trends hold in serum-rich medium commonly used in tissue culture, with the time constants of retraction much more closely tracking cortical stiffness than adhesive ligand density or cell spreading. These results support the use of cellular de-adhesion measurements to track cellular mechanical properties.
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33
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Analysis of Cytoskeleton-Destabilizing Agents by Optimized Optical Navigation and AFM Force Measurements. ACTA ACUST UNITED AC 2010. [DOI: 10.1017/s1551929510000131] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mechanical properties of cells are determined by the dynamic behavior of the cytoskeleton and physical interactions with the environment. The cytoskeleton, composed of actin filaments, intermediate filaments, and microtubules, is vital for numerous key cellular processes, such as cell division, vesicle trafficking, cell contraction, cell motility, and cell signaling. There is increasing evidence that deregulation of cytoskeletal components like disassembly of actin and tubulin filaments is an important parameter in cellular pathology. Thus, significant alterations of the mechanical phenotype of the cell and its surrounding microenvironment are reported to be involved in aberrant cellular processes and successively contribute to onset and progression of diseases such as cancer, malaria, and possibly neurodegeneration. In vitro and ex vivo biomechanical studies have shown that cancer cells have significantly decreased elastic moduli than their normal counterparts, a characteristic that is attributed to the ability of cancer cells to metastasize or spread.
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34
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Pelling AE, Veraitch FS, Chu CPK, Mason C, Horton MA. Mechanical dynamics of single cells during early apoptosis. ACTA ACUST UNITED AC 2009; 66:409-22. [PMID: 19492400 DOI: 10.1002/cm.20391] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Dynamic mechanical properties of cells are becoming recognized as indicators and regulators of physiological processes such as differentiation, malignant phenotypes and mitosis. A key process in development and homeostasis is apoptosis and whilst the molecular control over this pathway is well studied, little is known about the mechanical consequences of cell death. Here, we study the caspase-dependent mechanical kinetics of single cells during early apoptosis initiated with the general protein-kinase inhibitor staurosporine. This results in internal remodelling of the cytoskeleton and nucleus which is reflected in dynamic changes in the mechanical properties of the cell. Utilizing simultaneous confocal and atomic force microscopy (AFM), we measured distinct mechanical dynamics in the instantaneous cellular Young's Modulus and longer timescale viscous deformation. This allowed us to visualize time-dependent nuclear and cytoskeletal control of force dissipation with fluorescent fusion proteins throughout the cell. This work reveals that the cell death program not only orchestrates biochemical dynamics but also controls the mechanical breakdown of the cell. Importantly, the consequences of mechanical disregulation during apoptosis may be a contributing factor to several human pathologies through the poorly timed release of dead cells and cell debris.
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Affiliation(s)
- Andrew E Pelling
- Centre for Nanomedicine, The London Centre for Nanotechnology, University College London, London, United Kingdom.
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35
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Silberberg YR, Yakubov GE, Horton MA, Pelling AE. Cell nanomechanics and focal adhesions are regulated by retinol and conjugated linoleic acid in a dose-dependent manner. NANOTECHNOLOGY 2009; 20:285103. [PMID: 19546491 DOI: 10.1088/0957-4484/20/28/285103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Retinol and conjugated linoleic acid (CLA) have previously been shown to have an important role in gene expression and various cellular processes, including differentiation, proliferation and cell death. In this study we have investigated the effect of retinol and CLA, both individually and in combination, on the intracellular cytoskeleton, focal adhesions (FAs) and the nanomechanical properties of 3T3 fibroblasts. We observed a dose-dependent decrease in the formation of FAs following treatment with either compound, which was directly correlated to an increase in cell height (>30%) and a decrease in the measured Young's modulus (approximately 28%). Furthermore, treatments with both compounds demonstrated an increased effect and led to a reduction of >70% in the average number of FAs per cell and a decrease of >50% in average cell stiffness. These data reveal that retinol and CLA disrupt FA formation, leading to an increase in cell height and a significant decrease in stiffness. These results may broaden our understanding of the interplay between cell nanomechanics and cellular contact with the external microenvironment, and help to shed light on the important role of retinoids and CLA in health and disease.
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Affiliation(s)
- Yaron R Silberberg
- The London Centre for Nanotechnology and Centre for NanoMedicine, University College London, London, UK
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Silberberg YR, Pelling AE, Yakubov GE, Crum WR, Hawkes DJ, Horton MA. Mitochondrial displacements in response to nanomechanical forces. J Mol Recognit 2008; 21:30-6. [PMID: 18247356 DOI: 10.1002/jmr.868] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mechanical stress affects and regulates many aspects of the cell, including morphology, growth, differentiation, gene expression and apoptosis. In this study we show how mechanical stress perturbs the intracellular structures of the cell and induces mechanical responses. In order to correlate mechanical perturbations to cellular responses, we used a combined fluorescence-atomic force microscope (AFM) to produce well defined nanomechanical perturbations of 10 nN while simultaneously tracking the real-time motion of fluorescently labelled mitochondria in live cells. The spatial displacement of the organelles in response to applied loads demonstrates the highly dynamic mechanical response of mitochondria in fibroblast cells. The average displacement of all mitochondrial structures analysed showed an increase of approximately 40%, post-perturbation ( approximately 160 nm in comparison to basal displacements of approximately 110 nm). These results show that local forces can produce organelle displacements at locations far from the initial point of contact (up to approximately 40 microm). In order to examine the role of the cytoskeleton in force transmission and its effect on mitochondrial displacements, both the actin and microtubule cytoskeleton were disrupted using Cytochalasin D and Nocodazole, respectively. Our results show that there is no significant change in mitochondrial displacement following indentation after such treatments. These results demonstrate the role of the cytoskeleton in force transmission through the cell and on mitochondrial displacements. In addition, it is suggested that care must be taken when performing mechanical experiments on living cells with the AFM, as these local mechanical perturbations may have significant structural and even biochemical effects on the cell.
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Affiliation(s)
- Yaron R Silberberg
- The London Centre for Nanotechnology and Centre for NanoMedicine, University College London, 17-19 Gordon Street, London, WC1H 0AH, UK
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Cross SE, Jin YS, Tondre J, Wong R, Rao J, Gimzewski JK. AFM-based analysis of human metastatic cancer cells. NANOTECHNOLOGY 2008; 19:384003. [PMID: 21832563 DOI: 10.1088/0957-4484/19/38/384003] [Citation(s) in RCA: 231] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Recently biomechanics of cancer cells, in particular stiffness or elasticity, has been identified as an important factor relating to cancer cell function, adherence, motility, transformation and invasion. We report on the nanomechanical responses of metastatic cancer cells and benign mesothelial cells taken from human body cavity fluids using atomic force microscopy. Following our initial study (Cross et al 2007 Nat. Nanotechnol. 2 780-3), we report on the biophysical properties of patient-derived effusion cells and address the influence of cell morphology on measured cell stiffness. Using a cytocentrifugation method, which yields morphologically indistinguishable cells that can be prepared in 1 min and avoids any possible artifacts due to 12 h ex vivo culture, we find that metastatic tumor cells are more than 80% softer than benign cells with a distribution over six times narrower than that of normal cells. Consistent with our previous study, which yielded distinguishable cell populations based on ex vivo growth and morphological characteristics, our results show it is unlikely that morphology alone is sufficient to explain the difference in elastic moduli for these two cell types. Moreover, analysis of non-specific cell adhesion inherent to tumor and normal cells collected from patients show surface adhesion of tumor cells is ∼33% less adhesive compared to that of normal cells. Our findings indicate that biomechanical-based functional analysis may provide an additional platform for cytological evaluation and diagnosis of cancer in the future.
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Affiliation(s)
- Sarah E Cross
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA. California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA
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An historical perspective on cell mechanics. Pflugers Arch 2007; 456:3-12. [DOI: 10.1007/s00424-007-0405-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2007] [Revised: 11/12/2007] [Accepted: 11/15/2007] [Indexed: 11/26/2022]
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Pelling AE, Veraitch FS, Pui-Kei Chu C, Nicholls BM, Hemsley AL, Mason C, Horton MA. Mapping correlated membrane pulsations and fluctuations in human cells. J Mol Recognit 2007; 20:467-75. [PMID: 17712774 DOI: 10.1002/jmr.832] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The cell membrane and cytoskeleton are dynamic structures that are strongly influenced by the thermo-mechanical background in addition to biologically driven mechanical processes. We used atomic force microscopy (AFM) to measure the local membrane motion of human foreskin fibroblasts (HFFs) which were found to be governed by random and non-random correlated mechanical processes. Interphase cells displayed distinct membrane pulsations in which the membrane was observed to slowly contract upwards followed by a recovery to its initial position. These pulsations occurred one to three times per minute with variable amplitudes (20-100 pN) separated by periods of random baseline fluctuations with amplitudes of <20 pN. Cells were exposed to actin and microtubule (MT) destabilizing drugs and induced into early apoptosis. Mechanical pulsations (20-80 pN) were not prevented by actin or MT depolymerization but were prevented in early apoptotic cells which only displayed small amplitude baseline fluctuations (<20 pN). Correlation analysis revealed that the cell membrane motion is largely random; however several non-random processes, with time constants varying between approximately 2 and 35 s are present. Results were compared to measured cardiomyocyte motion which was well defined and highly correlated. Employing automated positioning of the AFM tip, interphase HFF correlation time constants were also mapped over a 10 microm2 area above the nucleus providing some insights into the spatial variability of membrane correlations. Here, we are able to show that membrane pulsations and fluctuations can be linked to physiological state and cytoskeletal dynamics through distinct sets of correlation time constants in human cells.
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Affiliation(s)
- Andrew E Pelling
- The London Centre for Nanotechnology, Centre for Nanomedicine, University College London, 17-19 Gordon Street, London WC1H 0AH, UK.
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Weihs D, Mason TG, Teitell MA. Effects of cytoskeletal disruption on transport, structure, and rheology within mammalian cells. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2007; 19:103102. [PMID: 19816550 PMCID: PMC2758690 DOI: 10.1063/1.2795130] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Quantification of cellular responses to stimuli is challenging. Cells respond to changing external conditions through internal structural and compositional and functional modifications, thereby altering their transport and mechanical properties. By properly interpreting particle-tracking microrheology, we evaluate the response of live cells to cytoskeletal disruption mediated by the drug nocodazole. Prior to administering the drug, the particles exhibit an apparently diffusive behavior that is actually a combination of temporally heterogeneous ballistic and caged motion. Selectively depolymerizing microtubules with the drug causes actively crawling cells to halt, providing a means for assessing drug efficacy, and making the caged motion of the probes readily apparent.
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Affiliation(s)
- Daphne Weihs
- Department of Pathology and Laboratory Medicine and Department of Chemistry and Biochemistry, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Thomas G. Mason
- Department of Chemistry and Biochemistry, Department of Physics and Astronomy, and California NanoSystems Institute, University of California at Los Angeles, Los Angeles, California 90095, USA
| | - Michael A. Teitell
- Department of Pathology and Laboratory Medicine, California NanoSystems Institute, Institute for Cell Mimetic Studies, Broad Center of Regenerative Medicine and Stem Cell Research, and Jonsson Comprehensive Cancer Center, University of California at Los Angeles, Los Angeles, California 90095, USA
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