Mean deformation metrics for quantifying 3D cell–matrix interactions without requiring information about matrix material properties

Mechanobiology relates cellular processes to mechanical signals, such as determining the effect of variations in matrix stiffness with cell tractions. Cell traction recorded via traction force microscopy (TFM) commonly takes place on materials such as polyacrylamide- and polyethylene glycol-based gels. Such experiments remain limited in physiological relevance because cells natively migrate within complex tissue microenvironments that are spatially heterogeneous and hierarchical. Yet, TFM requires determination of the matrix constitutive law (stress–strain relationship), which is not always readily available. In addition, the currently achievable displacement resolution limits the accuracy of TFM for relatively small cells. To overcome these limitations, and increase the physiological relevance of in vitro experimental design, we present a new approach and a set of associated biomechanical signatures that are based purely on measurements of the matrix's displacements without requiring any knowledge of its constitutive laws. We show that our mean deformation metrics (MDM) approach can provide significant biophysical information without the need to explicitly determine cell tractions. In the process of demonstrating the use of our MDM approach, we succeeded in expanding the capability of our displacement measurement technique such that it can now measure the 3D deformations around relatively small cells (∼10 micrometers), such as neutrophils. Furthermore, we also report previously unseen deformation patterns generated by motile neutrophils in 3D collagen gels.

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The influence of different geometries of matrix/scaffold on the remodeling process of a bone and bioresorbable material mixture with voids

Mathematics and Mechanics of Solids ◽

10.1177/1081286515616052 ◽

2015 ◽

Vol 22 (5) ◽

pp. 969-987 ◽

Cited By ~ 27

Author(s):

Ivan Giorgio ◽

Ugo Andreaus ◽

Tomasz Lekszycki ◽

Alessandro Della Corte

Keyword(s):

Bone Growth ◽

Matrix Material ◽

Porous Solids ◽

Artificial Material ◽

Matrix Deposition ◽

Aspect Ratios ◽

Adopted Model ◽

The Matrix ◽

Bioresorbable Material

Since internal architecture greatly influences crucial factors for tissue regeneration, such as nutrient diffusion, cell adhesion and matrix deposition, scaffolds have to be carefully designed, keeping in mind case-specific mechanical, mass transport and biological requirements. However, customizing scaffold architecture to better suit conflicting requirements, such as biological and mechanical ones, remains a challenging issue. Recent advances in printing technologies, together with the synthesis of novel composite biomaterials, have enabled the fabrication of various scaffolds with defined shape and controlled in vitro behavior. Thus, the influence of different geometries of the assemblage of the matrix and scaffold on the remodeling processes of living bone and artificial material should be investigated. To this end, two implant shapes are considered in this paper, namely a circular inclusion and a rectangular groove of different aspect ratios. A model of a mixture of bone tissue and bioresorbable material with voids was used to numerically analyze the physiological balance between the processes of bone growth and resorption and artificial material resorption in a plate-like sample. The adopted model was derived from a theory for the behavior of porous solids in which the matrix material is elastic and the interstices are void of material.

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Vesicle Size Regulates Nanotube Formation in the Cell

Scientific Reports ◽

10.1038/srep24002 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 20

Author(s):

Qian Peter Su ◽

Wanqing Du ◽

Qinghua Ji ◽

Boxin Xue ◽

Dong Jiang ◽

...

Keyword(s):

Single Molecule ◽

Model Systems ◽

Organelle Biogenesis ◽

Membrane Deformation ◽

Vesicle Size ◽

Cellular Processes ◽

Vesicle Recycling ◽

Physiological Relevance

Abstract Intracellular membrane nanotube formation and its dynamics play important roles for cargo transportation and organelle biogenesis. Regarding the regulation mechanisms, while much attention has been paid on the lipid composition and its associated protein molecules, effects of the vesicle size has not been studied in the cell. Giant unilamellar vesicles (GUVs) are often used for in vitro membrane deformation studies, but they are much larger than most intracellular vesicles and the in vitro studies also lack physiological relevance. Here, we use lysosomes and autolysosomes, whose sizes range between 100 nm and 1 μm, as model systems to study the size effects on nanotube formation both in vivo and in vitro. Single molecule observations indicate that driven by kinesin motors, small vesicles (100–200 nm) are mainly transported along the tracks while a remarkable portion of large vesicles (500–1000 nm) form nanotubes. This size effect is further confirmed by in vitro reconstitution assays on liposomes and purified lysosomes and autolysosomes. We also apply Atomic Force Microscopy (AFM) to measure the initiation force for nanotube formation. These results suggest that the size-dependence may be one of the mechanisms for cells to regulate cellular processes involving membrane-deformation, such as the timing of tubulation-mediated vesicle recycling.

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Chitosan-Based Thermo-Sensitive Hydrogel Loading Oyster Peptides for Hemostasis Application

Materials ◽

10.3390/ma13215038 ◽

2020 ◽

Vol 13 (21) ◽

pp. 5038

Author(s):

Dongying Zhang ◽

Zhang Hu ◽

Lingyu Zhang ◽

Sitong Lu ◽

Fengyan Liang ◽

...

Keyword(s):

Matrix Material ◽

Safety Evaluation ◽

Massive Hemorrhage ◽

Gelatin Sponge ◽

Glycerol Phosphate ◽

Modified Chitosan ◽

The Matrix ◽

Adsorption Rates

Uncontrolled massive hemorrhage is one of the principal causes of death in trauma emergencies. By using catechol-modified chitosan (CS-C) as the matrix material and β glycerol phosphate (β-GP) as a thermo-sensitive agent, chitosan-based thermo-sensitive hydrogel loading oyster peptides (CS-C/OP/β-GP) were prepared at physiological temperature. The hemostatic performance of CS-C/OP/β-GP hydrogel was tested in vivo and in vitro, and its biological safety was evaluated. The results showed that the in vitro coagulation time and blood coagulation index of CS-C/OP/β-GP hydrogel were better than those of a commercial gelatin sponge. Notably, compared with the gelatin sponge, CS-C/OP/β-GP hydrogel showed that the platelet adhesion and erythrocyte adsorption rates were 38.98% and 95.87% higher, respectively. Additionally, the hemostasis time in mouse liver injury was shortened by 19.5%, and the mass of blood loss in the mouse tail amputation model was reduced by 18.9%. The safety evaluation results demonstrated that CS-C/OP/β-GP had no cytotoxicity to L929 cells, and the hemolysis rates were less than 5% within 1 mg/mL, suggesting good biocompatibility. In conclusion, our results indicate that CS-C/OP/β-GP is expected to be a promising dressing in the field of medical hemostasis.

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Developing a multi-functional sensor for cell traction force, matrix remodeling and biomechanical assays in self-assembled 3D tissues in vitro

10.21203/rs.3.pex-1540/v1 ◽

2021 ◽

Author(s):

Bashar Emon ◽

M Saddam H Joy ◽

M Taher A Saif

Keyword(s):

Traction Force ◽

Patient Specific ◽

Matrix Remodeling ◽

Tissue Stiffness ◽

Cell Traction ◽

Primary Fibroblasts ◽

Multiple Cell ◽

Cell Matrix Interactions ◽

Cell Force

Abstract Cell-matrix interactions, mediated by cellular force and matrix remodeling, result in a dynamic reciprocity that drives numerous biological processes and disease progression. Currently, there is no available method for direct quantification cell traction force and matrix remodeling in 3D matrices as a function of time. To address this long-standing need, we recently developed a high-resolution microfabricated sensor1 that measures cell force, tissue-stiffness and can apply mechanical stimulation to the tissue. Here the tissue self-assembles and self-integrates with the sensor. With primary fibroblasts, cancer cells and neurons, we demonstrated the feasibility of the sensor by measuring single/multiple cell force with a resolution of 1 nN, and tissue stiffness1 due to matrix remodeling by the cells. The sensor can be translated into a high-throughput system for clinical assays such as patient-specific drug and phenotypic screening. In this paper, we present the detailed protocol for manufacturing the sensors, preparing experimental setup, developing assays with different tissues, and for imaging and analyzing the data.

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Engineered PLGA-PVP/VA based formulations to produce electro-drawn fast biodegradable microneedles for labile biomolecule delivery

Progress in Biomaterials ◽

10.1007/s40204-020-00143-2 ◽

2020 ◽

Vol 9 (4) ◽

pp. 203-217

Author(s):

Valentina Onesto ◽

Concetta Di Natale ◽

Martina Profeta ◽

Paolo Antonio Netti ◽

Raffaele Vecchione

Keyword(s):

Matrix Material ◽

Entrapment Efficiency ◽

Active Pharmaceutical Ingredient ◽

Release Profile ◽

Drug Release Profile ◽

The Matrix ◽

Emulsion Formulation ◽

Industrial Needs ◽

Mild Temperature

AbstractBiodegradable polymer microneedles (MNs) are recognized as non-toxic, safe and stable systems for advanced drug delivery and cutaneous treatments, allowing a direct intradermal delivery and in some cases a controlled release. Most of the microneedles found in the literature are fabricated by micromolding, which is a multistep thus typically costly process. Due to industrial needs, mold-free methods represent a very intriguing approach in microneedle fabrication. Electro-drawing (ED) has been recently proposed as an alternative fast, mild temperature and one-step strategy to the mold-based techniques for the fabrication of poly(lactic-co-glycolic acid) (PLGA) biodegradable MNs. In this work, taking advantage of the flexibility of the ED technology, we engineered microneedle inner microstructure by acting on the water-in-oil (W/O) precursor emulsion formulation to tune drug release profile. Particularly, to promote a faster release of the active pharmaceutical ingredient, we substituted part of PLGA with poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP/VA), as compared to the PLGA alone in the matrix material. Moreover, we introduced lecithin and maltose as emulsion stabilizers. Microneedle inner structural analysis as well as collagenase entrapment efficiency, release and activity of different emulsion formulations were compared to reach an interconnected porosity MN structure, aimed at providing an efficient protein release profile. Furthermore, MN mechanical properties were examined as well as its ability to pierce the stratum corneum on a pig skin model, while the drug diffusion from the MN body was monitored in an in vitro collagen-based dermal model at selected time points.

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Microscopic Matrix Remodeling Precedes Endothelial Morphological Changes During Capillary Morphogenesis

Journal of Biomechanical Engineering ◽

10.1115/1.4023984 ◽

2013 ◽

Vol 135 (7) ◽

Cited By ~ 12

Author(s):

Claire McLeod ◽

John Higgins ◽

Yekaterina Miroshnikova ◽

Rachel Liu ◽

Aliesha Garrett ◽

...

Keyword(s):

Endothelial Cells ◽

Morphological Changes ◽

Umbilical Vein ◽

Microscopic Analysis ◽

Matrix Remodeling ◽

Collagen Gels ◽

Surrounding Matrix ◽

The Matrix ◽

Umbilical Vein Endothelial Cells

The formation of microvascular networks (MVNs) is influenced by many aspects of the microenvironment, including soluble and insoluble biochemical factors and the biophysical properties of the surrounding matrix. It has also become clear that a dynamic and reciprocal interaction between the matrix and cells influences cell behavior. In particular, local matrix remodeling may play a role in driving cellular behaviors, such as MVN formation. In order to explore the role of matrix remodeling, an in vitro model of MVN formation involving suspending human umbilical vein endothelial cells within collagen hydrogels was used. The resulting cell and matrix morphology were microscopically observed and quantitative metrics of MVN formation and collagen gathering were applied to the resulting images. The macroscopic compaction of collagen gels correlates with the extent of MVN formation in gels of different stiffness values, with compaction preceding elongation leading to MVN formation. Furthermore, the microscopic analysis of collagen between cells at early timepoints demonstrates the alignment and gathering of collagen between individual adjacent cells. The results presented are consistent with the hypothesis that endothelial cells need to gather and align collagen between them as an early step in MVN formation.

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Study of Drug Release Kinetics from Sustained Release Matrix Tablets of Acyclovir using Natural Polymer Obtained from Colocasia Esculenta

International Journal of PharmTech Research ◽

10.20902/ijptr.2019.130306 ◽

2020 ◽

Vol 13 (3) ◽

pp. 172-179

Author(s):

Dharmendra Solanki ◽

Mohit Motiwale ◽

Sujata Mahapatra

Keyword(s):

Drug Release ◽

Sustained Release ◽

Release Kinetics ◽

Matrix Material ◽

Colocasia Esculenta ◽

Matrix Tablets ◽

Wet Granulation ◽

The Matrix ◽

Release Data

Sustained-release (SR) matrix tablets of Acyclovir and polysaccharide isolated from corms of Colocasia esculenta, at different drug to polymer ratios, were prepared by using wet granulation method. The formulated tablets were also characterized by physical and chemical parameters and results were found in acceptable limits. The investigation focuses on the influence of the proportion of the matrix material on the mechanism and the release rate of the drug from the tablets. In vitro drug release appears to occur both by diffusion and a swelling-controlled mechanism, indicates the drug release from the tablet was non-Fickian super case II transport. The drug release data fit well to the Zero-order drug release Model and the Korsmeyer equation.

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Enhancing Cell Migration in Collagen Gels by Modulating Collagen Adhesivity

ASME 2008 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2008-192945 ◽

2008 ◽

Author(s):

Gary A. Monteiro ◽

Harini G. Sundararaghavan ◽

Anthony V. Fernandes ◽

David I. Shreiber

Keyword(s):

Wound Healing ◽

Cell Migration ◽

Collagen Gels ◽

Structural Framework ◽

Tissue Equivalents ◽

Physiological Relevance ◽

A Cell ◽

Tractional Forces ◽

Regenerative Therapies

The organized movement of cells is critical during tissue morphogenesis and wound healing. While different tissue cells use distinct mechanisms for migration, the underlying biophysical balance of adhesive and tractional forces for effective migration is similar. The extracellular matrix provides the structural framework through which a cell can migrate. In particular, collagen is an abundant and ubiquitous ECM protein that supports cell migration. The excellent biocompatibility and physiological relevance of collagen have made it a primary material for tissue engineered regenerative therapies and in vitro studies with tissue equivalents.

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An Agent-Based Discrete Collagen Fiber Network Model of Dynamic Traction Force-Induced Remodeling

Journal of Biomechanical Engineering ◽

10.1115/1.4037947 ◽

2018 ◽

Vol 140 (5) ◽

Cited By ~ 3

Author(s):

James W. Reinhardt ◽

Keith J. Gooch

Keyword(s):

Strain Energy ◽

Traction Force ◽

Matrix Remodeling ◽

Microstructural Properties ◽

Collagen Gels ◽

Stress Strain ◽

Fiber Network ◽

Agent Based ◽

Collagen Remodeling

Microstructural properties of extracellular matrix (ECM) promote cell and tissue homeostasis as well as contribute to the formation and progression of disease. In order to understand how microstructural properties influence the mechanical properties and traction force-induced remodeling of ECM, we developed an agent-based model that incorporates repetitively applied traction force within a discrete fiber network. An important difference between our model and similar finite element models is that by implementing more biologically realistic dynamic traction, we can explore a greater range of matrix remodeling. Here, we validated our model by reproducing qualitative trends observed in three sets of experimental data reported by others: tensile and shear testing of cell-free collagen gels, collagen remodeling around a single isolated cell, and collagen remodeling between pairs of cells. In response to tensile and shear strain, simulated acellular networks with straight fibrils exhibited biphasic stress–strain curves indicative of strain-stiffening. When fibril curvature was introduced, stress–strain curves shifted to the right, delaying the onset of strain-stiffening. Our data support the notion that strain-stiffening might occur as individual fibrils successively align along the axis of strain and become engaged in tension. In simulations with a single, contractile cell, peak collagen displacement occurred closest to the cell and decreased with increasing distance. In simulations with two cells, compaction of collagen between cells appeared inversely related to the initial distance between cells. These results for cell-populated collagen networks match in vitro findings. A demonstrable benefit of modeling is that it allows for further analysis not feasible with experimentation. Within two-cell simulations, strain energy within the collagen network measured from the final state was relatively uniform around the outer surface of cells separated by 250 μm, but became increasingly nonuniform as the distance between cells decreased. For cells separated by 75 and 100 μm, strain energy peaked in the direction toward the other cell in the region in which fibrils become highly aligned and reached a minimum adjacent to this region, not on the opposite side of the cell as might be expected. This pattern of strain energy was partly attributable to the pattern of collagen compaction, but was still present when mapping strain energy divided by collagen density. Findings like these are of interest because fibril alignment, density, and strain energy may each contribute to contact guidance during tissue morphogenesis.

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The Modulus of Fibroblast-Populated Collagen Gels is not Determined by Final Collagen and Cell Concentration: Experiments and an Inclusion-Based Model

Journal of Biomechanical Engineering ◽

10.1115/1.4000064 ◽

2009 ◽

Vol 131 (10) ◽

Cited By ~ 23

Author(s):

Michael C. Evans ◽

Victor H. Barocas

Keyword(s):

Experimental Studies ◽

Model Fit ◽

Unexpected Result ◽

Collagen Gels ◽

Collagen Concentration ◽

Equilibrium Modulus ◽

The Matrix ◽

Material Theory ◽

Final Composition

The fibroblast-populated collagen lattice is an attractive model tissue for in vitro studies of cell behavior and as the basis for bioartificial tissues. In spite of its simplicity—containing only collagen and cells—the system is surprisingly difficult to describe mechanically because of the ability of the cells to remodel the matrix, including compaction at short times and synthesis and/or degradation (and cell proliferation) at longer times. The objectives of this work were to measure the equilibrium modulus of fibroblast-populated gels with different collagen and cell concentrations, and to use that characterization as the basis for a theoretical model that could be used to predict gel mechanics based on conditions. Although many observations were as expected (e.g., the gel compacts more when there are more cells in it, and the gel is stiffer when there is more collagen in it), an unexpected result arose: the final modulus of the gel was not dependent solely on the final composition. Even if it compacted more than a gel that was originally at a high collagen concentration, a gel that started at a low collagen concentration remained less stiff than the higher-concentration gel. In light of these results and experimental studies by others, we propose a model in which the gel compaction is not homogeneous but consists instead of extreme densification near the cells in an otherwise unchanged matrix. By treating the dense regions as spherical inclusions, we used classical composite material theory to develop an expression for the modulus of a compacted gel based on the initial collagen density and the final inclusion (i.e., cell) density. The new model fit the data for moderately compacted gels well but broke down, as expected, for larger volume fractions at which the underlying model assumptions did not apply.

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