scholarly journals Resolving Filament Level Mechanics in Collagen Networks using Activity Microscopy

2018 ◽  
Author(s):  
Emanuel N. Lissek ◽  
Tobias F. Bartsch ◽  
Ernst-Ludwig Florin
Keyword(s):  
Mechanical Properties ◽  
Local Environment ◽  
Thermal Fluctuations ◽  
Primary Component ◽  
Local Network ◽  
Two Dimensional ◽  
Single Filament ◽  
Matrix Interaction ◽  
Cell Matrix

AbstractCollagen is the most abundant protein in humans and the primary component of the extracellular matrix, a meshwork of biopolymer networks, which provides structure and integrity to tissues. Its mechanical properties profoundly influence the fate of cells. The cell-matrix interaction, however, is not well understood due to a lack of experimental techniques to study the mechanical interplay between cells and their local environment. Here we introduce Activity Microscopy, a new way to visualize local network mechanics with single filament resolution. Using collagen I networks in vitro, we localize fibril positions in two-dimensional slices through the network with nanometer precision and quantify the fibrils’ transverse thermal fluctuations with megahertz bandwidth. Using a fibril’s thermal fluctuations as an indicator for its tension, we find a heterogeneous stress distribution, where “cold” fibrils with small thermal fluctuations surround regions of highly fluctuating “hot” fibrils. We seed HeLa cells into collagen networks and quantify the anisotropy in the propagation of their forces.

Tunicamycin inhibits mouse tooth morphogenesis and odontoblast differentiation in vitro

Development ◽  
1980 ◽  
Vol 58 (1) ◽  
pp. 195-208
Author(s):  
Irma Thesleff ◽  
Robert M. Pratt
Keyword(s):  
Basement Membrane ◽  
Tooth Germ ◽  
Mesenchymal Cells ◽  
Protein Glycosylation ◽  
Molar Tooth ◽  
Odontoblast Differentiation ◽  
Matrix Interaction ◽  
Cell Matrix ◽  
Dose Dependent

Tunicamycin (TM), an antibiotic that selectively inhibits dolichol-mediated protein glycosylation, inhibited morphogenesis and differentiation of odontoblasts in the molar tooth germ in vitro. These effects of TM are reversible and dose-dependent, and in advanced teeth the effect of TM was not complete unless the basement membrane was removed prior to culture. TM did not prevent secretion of predentin or enamel when added to the cultures after initiation of predentin secretion. TM dramatically inhibited protein glycosylation and the accumulation of labeled proteoglycans and glycoproteins in the basement membrane. Our previous studies indicated that odontoblast differentiation is triggered by an interaction between the basement membrane and mesenchymal cells. We suggest that TM inhibits odontoblast differentiation by causing alterations in the basement membrane which prevent the necessary cell-matrix interaction required for odontoblast differentiation.

Understanding and Regulating Cell-Matrix Interactions Using Hydrogels of Designable Mechanical Properties

2021 ◽  
Vol 17 (2) ◽  
pp. 149-168
Author(s):  
Jiapeng Yang ◽  
Yu Zhang ◽  
Meng Qin ◽  
Wei Cheng ◽  
Wei Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Response ◽  
Research Direction ◽  
Mechanical Environment ◽  
Cell Functions ◽  
Cell Matrix ◽  
Matrix Interactions ◽  
Sense And Respond ◽  
Cell Matrix Interactions

Similar to natural tissues, hydrogels contain abundant water, so they are considered as promising biomaterials for studying the influence of the mechanical properties of extracellular matrices (ECM) on various cell functions. In recent years, the growing research on cellular mechanical response has revealed that many cell functions, including cell spreading, migration, tumorigenesis and differentiation, are related to the mechanical properties of ECM. Therefore, how cells sense and respond to the extracellular mechanical environment has gained considerable attention. In these studies, hydrogels are widely used as the in vitro model system. Hydrogels of tunable stiffness, viscoelasticity, degradability, plasticity, and dynamical properties have been engineered to reveal how cells respond to specific mechanical features. In this review, we summarize recent process in this research direction and specifically focus on the influence of the mechanical properties of the ECM on cell functions, how cells sense and respond to the extracellular mechanical environment, and approaches to adjusting the stiffness of hydrogels.

A REVIEW OF TWO-DIMENSIONAL IN VITRO CELL STRETCH PLATFORMS

2017 ◽  
Vol 17 (08) ◽  
pp. 1730003
Author(s):  
H. GHAZIZADEH ◽  
S. ARAVAMUDHAN
Keyword(s):  
Mechanical Properties ◽  
Biological System ◽  
Cellular Response ◽  
Mechanical Forces ◽  
Two Dimensional ◽  
Cell Stretch ◽  
And Behavior ◽  
Dimensional Cell

The focus of this paper is to describe the mechanism and behavior of two-dimensional in vitro cell stretch platforms, as well as discussing designs for the evaluation of mechanical properties of cells. It is extremely important to understand the cellular response to extrinsic mechanical forces as living biological system is constantly subjected to mechanical forces in vivo. In addition, this mechanistic understanding of cellular response will provide valuable information towards the design and fabrication of bioengineered tissues and organs, which are expected to replace and/or aid bodily functions. This paper will primarily focus on the development, advantages and limitations of two-dimensional cell stretch platforms.

scholarly journals Frustration-induced phases in migrating cell clusters

2018 ◽  
Vol 4 (9) ◽  
pp. eaar8483 ◽  
Author(s):  
Katherine Copenhagen ◽  
Gema Malet-Engra ◽  
Weimiao Yu ◽  
Giorgio Scita ◽  
Nir Gov ◽  
...  
Keyword(s):  
Experimental Data ◽  
Velocity Field ◽  
Cancer Cells ◽  
Collective Motion ◽  
Topological Defects ◽  
Local Environment ◽  
Two Dimensional ◽  
Agent Based ◽  
Heterogeneous Behavior

Certain malignant cancer cells form clusters in a chemoattractant gradient, which can spontaneously show three different phases of motion: translational, rotational, and random. Guided by our experiments on the motion of two-dimensional clusters in vitro, we developed an agent-based model in which the cells form a cohesive cluster due to attractive and alignment interactions. We find that when cells at the cluster rim are more motile, all three phases of motion coexist, in agreement with our observations. Using the model, we show that the transitions between different phases are driven by competition between an ordered rim and a disordered core accompanied by the creation and annihilation of topological defects in the velocity field. The model makes specific predictions, which we verify with our experimental data. Our results suggest that heterogeneous behavior of individuals, based on local environment, can lead to novel, experimentally observed phases of collective motion.

Specific Labeling of Protein Domains with Antibody Fragments

1981 ◽  
Vol 39 ◽  
pp. 416-417
Author(s):  
U. Aebi ◽  
L.E. Buhle ◽  
W.E. Fowler
Keyword(s):  
Image Processing ◽  
Specific Protein ◽  
Antibody Fragments ◽  
Supramolecular Organization ◽  
Two Dimensional ◽  
Ordered Structures ◽  
Virus Capsids ◽  
Processing Techniques

Many important supramolecular structures such as filaments, microtubules, virus capsids and certain membrane proteins and bacterial cell walls exist as ordered polymers or two-dimensional crystalline arrays in vivo. In several instances it has been possible to induce soluble proteins to form ordered polymers or two-dimensional crystalline arrays in vitro. In both cases a combination of electron microscopy of negatively stained specimens with analog or digital image processing techniques has proven extremely useful for elucidating the molecular and supramolecular organization of the constituent proteins. However from the reconstructed stain exclusion patterns it is often difficult to identify distinct stain excluding regions with specific protein subunits. To this end it has been demonstrated that in some cases this ambiguity can be resolved by a combination of stoichiometric labeling of the ordered structures with subunit-specific antibody fragments (e.g. Fab) and image processing of the electron micrographs recorded from labeled and unlabeled structures.

Cytocompatibility and Material Properties of Poly-carbonate Urethane/Carbon Nanofiber Composites for Neural Applications

2003 ◽  
Vol 774 ◽  
Author(s):  
Janice L. McKenzie ◽  
Michael C. Waid ◽  
Riyi Shi ◽  
Thomas J. Webster
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanofibers ◽  
Material Properties ◽  
Carbon Nanofiber ◽  
Scar Tissue ◽  
Tissue Response ◽  
Positive Interactions ◽  
Weight Percentage ◽  
Poly Carbonate

AbstractCarbon nanofibers possess excellent conductivity properties, which may be beneficial in the design of more effective neural prostheses, however, limited evidence on their cytocompatibility properties exists. The objective of the present in vitro study was to determine cytocompatibility and material properties of formulations containing carbon nanofibers to predict the gliotic scar tissue response. Poly-carbonate urethane was combined with carbon nanofibers in varying weight percentages to provide a supportive matrix with beneficial bulk electrical and mechanical properties. The substrates were tested for mechanical properties and conductivity. Astrocytes (glial scar tissue-forming cells) were seeded onto the substrates for adhesion. Results provided the first evidence that astrocytes preferentially adhered to the composite material that contained the lowest weight percentage of carbon nanofibers. Positive interactions with neurons, and, at the same time, limited astrocyte functions leading to decreased gliotic scar tissue formation are essential for increased neuronal implant efficacy.

scholarly journals Anti-Inflammatory Properties of Injectable Betamethasone-Loaded Tyramine-Modified Gellan Gum/Silk Fibroin Hydrogels

Biomolecules ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1456
Author(s):  
Isabel Matos Oliveira ◽  
Cristiana Gonçalves ◽  
Myeong Eun Shin ◽  
Sumi Lee ◽  
Rui Luis Reis ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Mechanical Properties ◽  
Silk Fibroin ◽  
Therapeutic Efficacy ◽  
Composite Structures ◽  
Gelation Time ◽  
Polymeric Materials ◽  
Gellan Gum ◽  
Traditional Use

Rheumatoid arthritis is a rheumatic disease for which a healing treatment does not presently exist. Silk fibroin has been extensively studied for use in drug delivery systems due to its uniqueness, versatility and strong clinical track record in medicine. However, in general, natural polymeric materials are not mechanically stable enough, and have high rates of biodegradation. Thus, synthetic materials such as gellan gum can be used to produce composite structures with biological signals to promote tissue-specific interactions while providing the desired mechanical properties. In this work, we aimed to produce hydrogels of tyramine-modified gellan gum with silk fibroin (Ty–GG/SF) via horseradish peroxidase (HRP), with encapsulated betamethasone, to improve the biocompatibility and mechanical properties, and further increase therapeutic efficacy to treat rheumatoid arthritis (RA). The Ty–GG/SF hydrogels presented a β-sheet secondary structure, with gelation time around 2–5 min, good resistance to enzymatic degradation, a suitable injectability profile, viscoelastic capacity with a significant solid component and a betamethasone-controlled release profile over time. In vitro studies showed that Ty–GG/SF hydrogels did not produce a deleterious effect on cellular metabolic activity, morphology or proliferation. Furthermore, Ty–GG/SF hydrogels with encapsulated betamethasone revealed greater therapeutic efficacy than the drug applied alone. Therefore, this strategy can provide an improvement in therapeutic efficacy when compared to the traditional use of drugs for the treatment of rheumatoid arthritis.

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