Alignment of fibroblasts on grooved surfaces described by a simple geometric transformation

1986 ◽  
Vol 83 (1) ◽  
pp. 313-340 ◽  
Author(s):  
G.A. Dunn ◽  
A.F. Brown
Keyword(s):  
Cell Shape ◽  
Groove Width ◽  
Geometric Transformation ◽  
Cell Alignment ◽  
Cellular Mechanisms ◽  
Planar Surfaces ◽  
Video Images ◽  
Cell Shapes ◽  
Chick Heart ◽  
Ridge Width

The response of chick heart fibroblasts to grooved substrata was studied using microfabricated grooves and new measures of shape and alignment derived from the moments of cell shapes. Cell shape and alignment were measured on 23 different sets of regular, parallel grooves, which ranged in width from 1.65 to 8.96 micron, and in repeat spacing from 3.0 to 32.0 micron. The grooves were of constant depth, 0.69 micron. Digitized video images were analysed to extract the zero-, first- and second-order moments of the cell shapes, from which were calculated three measures of cell shape, and three measures of cell alignment. Regression analyses of the measures against parameters of the substratum such as groove width, repeat spacing and the ridge width between grooves show that ridge width is the main parameter affecting cell alignment (alignment being inversely proportional to ridge width), although groove width has a small additional effect. All the differences in cell shape between the different grooves can be summarized to a very good approximation as simple geometrical stretch transformations of the shapes of cells on planar surfaces. Our principal measure of cell alignment, paraxial elongation, is a measure of the necessary transformation. This finding has the interesting biological implication that the shape and orientation adopted by cells, in response to the grooves, are not governed by independent cellular mechanisms.

scholarly journals Anisotropy links cell shapes to a solid-to-fluid transition during convergent extension

2019 ◽  
Author(s):  
Xun Wang ◽  
Matthias Merkel ◽  
Leo B. Sutter ◽  
Gonca Erdemci-Tandogan ◽  
M. Lisa Manning ◽  
...  
Keyword(s):  
Cell Shape ◽  
Shape Index ◽  
Convergent Extension ◽  
Cell Alignment ◽  
Cell Rearrangement ◽  
Internal Cell ◽  
Cell Patterns ◽  
Cell Shapes ◽  
Tissue Reorganization ◽  
External Forces

AbstractWithin developing embryos, tissues flow and reorganize dramatically on timescales as short as minutes. This includes epithelial tissues, which often narrow and elongate in convergent extension movements due to anisotropies in external forces or in internal cell-generated forces. However, the mechanisms that allow or prevent tissue reorganization, especially in the presence of strongly anisotropic forces, remain unclear. We study this question in the converging and extending Drosophila germband epithelium, which displays planar polarized myosin II and experiences anisotropic forces from neighboring tissues, and we show that in contrast to isotropic tissues, cell shape alone is not sufficient to predict the onset of rapid cell rearrangement. From theoretical considerations and vertex model simulations, we predict that in anisotropic tissues two experimentally accessible metrics of cell patterns—the cell shape index and a cell alignment index—are required to determine whether an anisotropic tissue is in a solid-like or fluid-like state. We show that changes in cell shape and alignment over time in the Drosophila germband indicate a solid-to-fluid transition that corresponds to the onset of cell rearrangement and convergent extension in wild-type embryos and are also consistent with more solid-like behavior in bnt mutant embryos. Thus, the onset of cell rearrangement in the germband can be predicted by a combination of cell shape and alignment. These findings suggest that convergent extension is associated with a transition to more fluid-like tissue behavior, which may help accommodate tissue shape changes during rapid developmental events.

scholarly journals Time-lapse observation of cell alignment on nanogrooved patterns

2009 ◽  
Vol 6 (suppl_3) ◽  
Author(s):  
Satoshi Fujita ◽  
Masahiro Ohshima ◽  
Hiroo Iwata
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Time Lapse ◽  
Groove Depth ◽  
Groove Width ◽  
Cell Alignment ◽  
Cell Protrusion ◽  
Open Questions ◽  
Ridge Width ◽  
As If

Cells elongate on a surface with nanogrooved (NG) patterns and align along that pattern. Although various models have been proposed for how this occurs, much remains to be clarified. Studies with fixed cells do not lend themselves to answering some of these open questions. In this study, the dynamic behaviours of living mesenchymal stem cells on an NG substrate with a 200 nm groove depth, an 870 nm ridge width and a 670 nm groove width were observed using time-lapse microscopes. We found that filopodia moved as if they were probing the surroundings of the cell protrusion, and then some cell protrusions invaded the probed areas. Cell protrusions that extended perpendicular to the NG direction tended to retract more rapidly than those parallel to the grooves. From these facts, we think that the retracting phase of cell protrusions play a rule in cell alignment along the NG patterns.

scholarly journals Anisotropy links cell shapes to tissue flow during convergent extension

2020 ◽  
Vol 117 (24) ◽  
pp. 13541-13551 ◽  
Author(s):  
Xun Wang ◽  
Matthias Merkel ◽  
Leo B. Sutter ◽  
Gonca Erdemci-Tandogan ◽  
M. Lisa Manning ◽  
...  
Keyword(s):  
Cell Shape ◽  
Shape Index ◽  
Convergent Extension ◽  
Cell Alignment ◽  
Cell Rearrangement ◽  
Internal Cell ◽  
Cell Patterns ◽  
Cell Shapes ◽  
Tissue Reorganization ◽  
External Forces

Within developing embryos, tissues flow and reorganize dramatically on timescales as short as minutes. This includes epithelial tissues, which often narrow and elongate in convergent extension movements due to anisotropies in external forces or in internal cell-generated forces. However, the mechanisms that allow or prevent tissue reorganization, especially in the presence of strongly anisotropic forces, remain unclear. We study this question in the converging and extendingDrosophilagermband epithelium, which displays planar-polarized myosin II and experiences anisotropic forces from neighboring tissues. We show that, in contrast to isotropic tissues, cell shape alone is not sufficient to predict the onset of rapid cell rearrangement. From theoretical considerations and vertex model simulations, we predict that in anisotropic tissues, two experimentally accessible metrics of cell patterns—the cell shape index and a cell alignment index—are required to determine whether an anisotropic tissue is in a solid-like or fluid-like state. We show that changes in cell shape and alignment over time in theDrosophilagermband predict the onset of rapid cell rearrangement in both wild-type andsnail twistmutant embryos, where our theoretical prediction is further improved when we also account for cell packing disorder. These findings suggest that convergent extension is associated with a transition to more fluid-like tissue behavior, which may help accommodate tissue-shape changes during rapid developmental events.

scholarly journals A Dynamic Stochastic Model of Frequency-Dependent Stress Fiber Alignment Induced by Cyclic Stretch

2009 ◽  
Author(s):  
Hui-Ju Hsu ◽  
Chin-Fu Lee ◽  
Roland Kaunas
Keyword(s):  
Cell Shape ◽  
Principal Direction ◽  
Focal Adhesions ◽  
Cyclic Stretch ◽  
Cell Alignment ◽  
Cellular Functions ◽  
Fiber Alignment ◽  
Dynamic Stochastic ◽  
Dynamic Structures ◽  
Point Level

Actin stress fibers (SFs) are bundles of actin filaments anchored at each end via focal adhesions. Myosin-generated contraction leads to the development of tension, which extends SFs beyond their unloaded lengths. In human aortic ECs, the level of SF extension is maintained at a set-point level of ∼1.10 (1). SFs are also dynamic structures and their continuous assembly and disassembly is critical to cellular functions involving changes in cell shape. Further, deformation of the extracellular matrix perturbs SF extension, leading to compensatory responses such as the gradual alignment of SFs perpendicular to the principal direction of cyclic stretch. The extent of cell alignment has been shown to depend on the pattern of matrix stretch; however, it is unclear how cells distinguish between different patterns of stretch to determine their unique responses.

A Mechanistic Motor-Clutch Model That Explains Cell Shape Dynamics to Cyclic Stretch

2022 ◽  
Author(s):  
Benjamin W. Scandling ◽  
Jia Gou ◽  
Jessica Thomas ◽  
Jacqueline Xuan ◽  
Chuan Xue ◽  
...  
Keyword(s):  
Computational Model ◽  
Computational Models ◽  
The Body ◽  
Cyclic Stretch ◽  
Substrate Stiffness ◽  
Cell Alignment ◽  
Cellular Mechanisms ◽  
Actin Bundles ◽  
The Impact

Many cells in the body experience cyclic mechanical loading, which can impact cellular processes and morphology. In vitro studies often report that cells reorient in response to cyclic stretch of their substrate. To explore cellular mechanisms involved in this reorientation, a computational model was developed by utilizing the previous computational models of the actin-myosin-integrin motor-clutch system developed by others. The computational model predicts that under most conditions, actin bundles align perpendicular to the direction of applied cyclic stretch, but under specific conditions, such as low substrate stiffness, actin bundles align parallel to the direction of stretch. The model also predicts that stretch frequency impacts the rate of reorientation, and that proper myosin function is critical in the reorientation response. These computational predictions are consistent with reports from the literature and new experimental results presented here. The model suggests that the impact of different stretching conditions (stretch type, amplitude, frequency, substrate stiffness, etc.) on the direction of cell alignment can largely be understood by considering their impact on cell-substrate detachment events, specifically whether detachment occurs during stretching or relaxing of the substrate.

Regulation of cell shape in Euglena gracilis. III. Involvement of stable microtubules

1985 ◽  
Vol 74 (1) ◽  
pp. 219-237
Author(s):  
C.L. Lachney ◽  
T.A. Lonergan
Keyword(s):  
Euglena Gracilis ◽  
Cell Shape ◽  
Microtubule Assembly ◽  
Live Cells ◽  
Microtubule Depolymerization ◽  
Cytoplasmic Microtubule ◽  
Intact Cells ◽  
Calmodulin Antagonist ◽  
Cell Shapes ◽  
In Cells

The role of cytoplasmic microtubules in a recently reported biological clock-controlled rhythm in cell shape of the alga Euglena gracilis (strain Z) was examined using indirect immunofluorescence microscopy. The resulting fluorescent patterns indicated that, unlike many other cell systems, Euglena cells apparently change from round to long to round cell shape without associated cytoplasmic microtubule assembly and disassembly. Instead, the different cell shapes were correlated with microtubule patterns, which suggested that movement of stable microtubules to accomplish cell shape changes. In live intact cells, these microtubules were demonstrated by immunofluorescence to be stable to lowered temperature and elevated intracellular Ca2+ levels, treatments that are commonly used to depolymerize microtubules. In cells extracted in detergent at low temperature or in the presence of elevated Ca2+ levels, the fluorescent image of the microtubules was disrupted. Transmission electron microscopy confirmed the loss of one subset of pellicle microtubules. The difference in microtubule stability to these agents between live intact cells and cells extracted in detergent suggested the presence of a microtubule-stabilizing factor in live cells, which is released from the cell by extraction with detergent, thereby permitting microtubule depolymerization by Ca2+ or lowered temperature. The calmodulin antagonist trifluoperazine prevented the Ca2+-induced disruption of the fluorescent microtubule pattern in cells extracted in detergent. These results implied the involvement of calmodulin in the sensitivity to Ca2+ of the microtubules of cells extracted in detergent.

scholarly journals Molar Bud-to-Cap Transition Is Proliferation Independent

2019 ◽  
Vol 98 (11) ◽  
pp. 1253-1261 ◽  
Author(s):  
S. Yamada ◽  
R. Lav ◽  
J. Li ◽  
A.S. Tucker ◽  
J.B.A. Green
Keyword(s):  
Cell Proliferation ◽  
Cell Shape ◽  
Tooth Germ ◽  
Odontogenic Epithelium ◽  
Differential Cell ◽  
Cell Shapes ◽  
Genetic Mechanisms ◽  
Cell Trajectory ◽  
Tooth Germs ◽  
Different Parts

Tooth germs undergo a series of dynamic morphologic changes through bud, cap, and bell stages, in which odontogenic epithelium continuously extends into the underlying mesenchyme. During the transition from the bud stage to the cap stage, the base of the bud flattens and then bends into a cap shape whose edges are referred to as “cervical loops.” Although genetic mechanisms for cap formation have been well described, little is understood about the morphogenetic mechanisms. Computer modeling and cell trajectory tracking have suggested that the epithelial bending is driven purely by differential cell proliferation and adhesion in different parts of the tooth germ. Here, we show that, unexpectedly, inhibition of cell proliferation did not prevent bud-to-cap morphogenesis. We quantified cell shapes and actin and myosin distributions in different parts of the tooth epithelium at the critical stages and found that these are consistent with basal relaxation in the forming cervical loops and basal constriction around enamel knot at the center of the cap. Inhibition of focal adhesion kinase, which is required for basal constriction in other systems, arrested the molar explant morphogenesis at the bud stage. Together, these results show that the bud-to-cap transition is largely proliferation independent, and we propose that it is driven by classic actomyosin-driven cell shape–dependent mechanisms. We discuss how these results can be reconciled with the previous models and data.

scholarly journals An effective model for quantification of cell 3Dshape in early embryogenesis

2021 ◽  
Author(s):  
Zelin Li ◽  
Jianfeng Cao ◽  
Zhongying Zhao ◽  
Hong Yan
Keyword(s):  
Cell Fate ◽  
Cell Shape ◽  
Developmental Process ◽  
Morphological Changes ◽  
Shape Space ◽  
Effective Model ◽  
Cell Stage ◽  
Cell Shapes ◽  
Dimensional Shape ◽  
Low Dimensional

Abstract Background: The developmental process is featured by fabulous morphogenesis in multicellular organisms. Describing morphological changes quantitatively concretes the way to investigating both intra and inter cell regulations on cell fate. While Caenorhabditis elegans has been used as a model for cell and development studies for a long time, the exploration of how cell shape is precisely controlled keeps obscured by the lack of methods to model morphological features. Currently, in order to characterize the features of cell shape involved in cell migration and differentiation, there is an increasing demand in analyzing cell shape systematically, especially when many works have contributed to cell reconstruction. Results: In this work, Spherical harmonics and Principal component analysis integrated Cell Shape quantification Models (SPCSMs) is proposed to represent cell shapes in a low-dimensional shape space. SPCSMs incorporates a complete pipeline to quantify cell shapes and analyze their morphological phenotypes in three dimensional (3D) reconstructions. Based on the framework, we extract biological patterns in the lineage of C. elegans embryo before 350-cell stage, during which all hypodermis cells deformed like a funnel and can be recognized by this shape pattern. Finally, SPCSMs is compared with two cell shape representation methods, which substantiates the effectiveness and robustness of our method. Conclusion: SPCSMs provides a general method to decribe shapes in low-dimensional shape space with compact parameters. It can quantify the shapes of cells from single-cell resolution images obtained over one-minute intervals, making it possible for the recognition of developmental patterns in cell lineages. SPCSMs is expected to be an effective model for biologists to explore the relationships between the shapes of cells and their fates.

scholarly journals PalaCell2D: A framework for detailed tissue morphogenesis

2021 ◽  
Author(s):  
Raphaël Conradin ◽  
Christophe Coreixas ◽  
Jonas Latt ◽  
Bastien Chopard
Keyword(s):  
Internal Pressure ◽  
Tissue Growth ◽  
Cellular Mechanisms ◽  
Simple Description ◽  
Biologically Relevant ◽  
In Vivo Experiments ◽  
Cell Shapes ◽  
And Migration ◽  
The Impact

AbstractIn silico, cell based approaches for modeling biological morphogenesis are used to test and validate our understanding of the biological and mechanical process that are at work during the growth and the organization of multi-cell tissues. As compared to in vivo experiments, computer based frameworks dedicated to tissue modeling allow us to easily test different hypotheses, and to quantify the impact of various biophysically relevant parameters.Here, we propose a formalism based on a detailed, yet simple, description of cells that accounts for intra-, inter- and extra-cellular mechanisms. More precisely, the cell growth and division is described through the space and time evolution of the membrane vertices. These vertices follow a Newtonian dynamics, meaning that their evolution is controlled by different types of forces: a membrane force (spring and bending), an adherence force (inter-cellular spring), external and internal pressure forces. Different evolution laws can be applied on the internal pressure, depending on the intra-cellular mechanism of interest. In addition to the cells dynamics, our formalism further relies on a lattice Boltzmann method, using the Palabos library, to simulate the diffusion of chemical signals. The latter aims at driving the growth and migration of a tissue by simply changing the state of the cells.All of this leads to an accurate description of the growth and division of cells, with realistic cell shapes and where membranes can have different properties. While this work is mainly of methodological nature, we also propose to validate our framework through simple, yet biologically relevant benchmark tests at both single-cell and full tissue scales. This includes free and chemically controlled cell tissue growth in an unbounded domain. The ability of our framework to simulate cell migration, cell compression and morphogenesis under external constraints is also investigated in a qualitative manner.

scholarly journals Anticorrosion Behaviour of SS304 Microgroove Surfaces in Saline Water

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1543
Author(s):  
Vivek Anand Annakodi ◽  
Ramachandra Arvind Singh ◽  
Subramanian Jayalakshmi ◽  
Yupeng Zhang ◽  
Koppula Srinivas Rao ◽  
...  
Keyword(s):  
Steel Surface ◽  
Corrosion Behaviour ◽  
Salt Water ◽  
Groove Width ◽  
Surface Wettability ◽  
304 Stainless Steel ◽  
Width Ratio ◽  
Nacl Solution ◽  
Ridge Width

The 304 Stainless Steel (SS304) is severely affected by salt water corrosion due to its high surface wettability. By reducing its surface wettability, its corrosion can be reduced. To achieve this, topographical modification of the steel surface is an effective route. In this work, SS304 flat surfaces were topographically modified into microgrooves (ridge width 250 μm to 500 μm, groove width 200 μm, width ratio = ridge width/groove width >1). Wire cut electrical discharge machining was used to fabricate the microgrooves. Long-term wetting characteristics and long-term corrosion behaviour of flat surface and microgrooves were studied. The influence of the nature of wetting of the tested surfaces on their corrosion behaviour was examined. The sessile drop method and potentiodynamic polarization tests in sodium chloride (3.5 wt. % NaCl) solution (intermittent and continuous exposures for 168 h) were studied to characterize their wetting and corrosion behaviours, respectively. Topographical modification imparted long-term hydrophobicity and, as a consequence, long-term anticorrosion ability of the steel surface. Micropatterning reduced the corrosion rate by two orders of magnitude due to reduction in interfacial contact area with the corrosive fluid via composite wetting, i.e., solid–liquid–air interface. Microgrooves showed corrosion inhibition efficiency ≥88%, upon long-term exposure to NaCl solution. By comparing the wetting and corrosion behaviours of the microgrooves with those of the previously studied microgrooves (ridge width/groove width <1), it was found that the surface roughness of their ridges strongly influences their wetting and corrosion properties.

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