The Effect of the Endothelial Cell Cortex on Atomic Force Microscopy Measurements

Vargas-Pinto, Rocio; Gong, Haiyan; Vahabikashi, Amir; Johnson, Mark

doi:10.1016/j.bpj.2013.05.034

Cited by 160 publications

(204 citation statements)

References 58 publications

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“…The related elastic moduli are calculated using the Hertz model (SI Text) (23,24). Note that the determined absolute moduli values depend on the tip shape and the used fitting model; sharp tips are expected to rather probe the local mechanics of the underlying fibrous network (SI Text) (25)(26)(27). The deduced elastic moduli recorded along the follicle axis are shown as boxplots in Fig.…”

Section: Resultsmentioning

confidence: 99%

Keratin network modifications lead to the mechanical stiffening of the hair follicle fiber

Bornschlögl

Bildstein

Thibaut

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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The complex mechanical properties of biomaterials such as hair, horn, skin, or bone are determined by the architecture of the underlying fibrous bionetworks. Although much is known about the influence of the cytoskeleton on the mechanics of isolated cells, this has been less studied in tridimensional tissues. We used the hair follicle as a model to link changes in the keratin network composition and architecture to the mechanical properties of the nascent hair. We show using atomic force microscopy that the soft keratinocyte matrix at the base of the follicle stiffens by a factor of ∼360, from 30 kPa to 11 MPa along the first millimeter of the follicle. The early mechanical stiffening is concomitant to an increase in diameter of the keratin macrofibrils, their continuous compaction, and increasingly parallel orientation. The related stiffening of the material follows a power law, typical of the mechanics of nonthermal bending-dominated fiber networks. In addition, we used X-ray diffraction to monitor changes in the (supra)molecular organization within the keratin fibers. At later keratinization stages, the inner mechanical properties of the macrofibrils dominate the stiffening due to the progressive setting up of the cystine network. Our findings corroborate existing models on the sequence of biological and structural events during hair keratinization.atomic force microscopy | elastic modulus | human hair follicle | biomechanics | X-ray diffraction B iological tissues are structurally complex materials with remarkable mechanics and elastic moduli that can range from a few pascals to several gigapascals (1-3). An active field aims at understanding how the local structural and mechanical properties of bionetworks define its macroscopic mechanics from a molecular scale toward a cellular and tissue scale (4-6). One challenge is that the properties of these networks have to be considered over multiple length and force scales with macroscopic mechanical forces being transduced from the whole tissue scale down to the cellular and molecular level and vice versa.At the cellular level, the last decades witnessed for a considerable advancement toward a better understanding of how the cytoskeleton composed of actin, microtubules, and intermediate filaments (IFs) determines cellular mechanics (1,(6)(7)(8). In vitro studies on isolated cells (6) and reconstituted in vitro bionetworks with controllable architecture and composition (9-12) considerably advanced our knowledge of cytoskeletal mechanics. However, these models are only approximations of the complex tridimensional architecture of most tissues. At the tissue level, the mechanical anisotropy together with the variety of mechanically different constituents usually hamper direct correlations between network architecture and mechanical properties (3, 13). Analytical models and computer modeling allow to theoretically link the macroscopic mechanical properties of the network with parameters of the local network architecture (5, 14, 15).The human hair follicle was used here...

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Section: Resultsmentioning

confidence: 99%

Keratin network modifications lead to the mechanical stiffening of the hair follicle fiber

Bornschlögl

Bildstein

Thibaut

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…In our simulations of cell indentation, the endothelial cell is modeled as a nearly incompressible (14,27) hyperelastic neo-Hookean (13,28,29) material, with a Poisson's ratio of 0.49 and a Young's modulus of 1 kPa. The microindenter's spherical tip is considered infinitely rigid compared to the cell.…”

Section: Simulations Of Cell Indentationmentioning

confidence: 99%

Mechanical Criterion for the Rupture of a Cell Membrane under Compression

Gonzalez‐Rodriguez

Guillou

Cornat

et al. 2016

Biophysical Journal

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We investigate the mechanical conditions leading to the rupture of the plasma membrane of an endothelial cell subjected to a local, compressive force. Membrane rupture is induced by tilted microindentation, a technique used to perform mechanical measurements on adherent cells. In this technique, the applied force can be deduced from the measured horizontal displacement of a microindenter's tip, as imaged with an inverted microscope and without the need for optical sensors to measure the microindenter's deflection. We show that plasma membrane rupture of endothelial cells occurs at a well-defined value of the applied compressive stress. As a point of reference, we use numerical simulations to estimate the magnitude of the compressive stresses exerted on endothelial cells during the deployment of a stent.

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“…where υ is the Poisson ratio of cell; cells are often considered as incompressible material and thus υ=0.5 (Vargas-Pinto et al, 2013;Nijenhuis et al, 2014;Hecht et al, 2015). F is the applied loading force of AFM probe; δ is the indentation depth; E is the Young's modulus of the celll θ is the half-opening angle of the conical tip; and R is the radius of spherical tip.…”

Section: Discussionmentioning

confidence: 99%

Atomic force microscopy studies on cellular elastic and viscoelastic properties

Liu

et al. 2017

Sci. China Life Sci.

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In this work, a method based on atomic force microscopy (AFM) approach-reside-retract experiments was established to simultaneously quantify the elastic and viscoelastic properties of single cells. First, the elastic and viscoelastic properties of normal breast cells and cancerous breast cells were measured, showing significant differences in Young's modulus and relaxation times between normal and cancerous breast cells. Remarkable differences in cellular topography between normal and cancerous breast cells were also revealed by AFM imaging. Next, the elastic and viscoelasitc properties of three other types of cell lines and primary normal B lymphocytes were measured; results demonstrated the potential of cellular viscoelastic properties in complementing cellular Young's modulus for discerning different states of cells. This research provides a novel way to quantify the mechanical properties of cells by AFM, which allows investigation of the biomechanical behaviors of single cells from multiple aspects.

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The Effect of the Endothelial Cell Cortex on Atomic Force Microscopy Measurements

Cited by 160 publications

References 58 publications

Keratin network modifications lead to the mechanical stiffening of the hair follicle fiber

Keratin network modifications lead to the mechanical stiffening of the hair follicle fiber

Mechanical Criterion for the Rupture of a Cell Membrane under Compression

Atomic force microscopy studies on cellular elastic and viscoelastic properties

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