Risky interpretations across the length scales: continuum vs. discrete models for soft tissue mechanobiology

Biomechanics and Modeling in Mechanobiology ◽

10.1007/s10237-021-01543-4 ◽

2022 ◽

Author(s):

Alberto Stracuzzi ◽

Ben R. Britt ◽

Edoardo Mazza ◽

Alexander E. Ehret

Keyword(s):

Structural Model ◽

Mechanical Response ◽

Tissue Response ◽

Discrete Models ◽

Fibre Network ◽

Essential Question ◽

Mechanical Approach ◽

Sense And Respond ◽

Orientation Statistics

AbstractModelling and simulation in mechanobiology play an increasingly important role to unravel the complex mechanisms that allow resident cells to sense and respond to mechanical cues. Many of the in vivo mechanical loads occur on the tissue length scale, thus raising the essential question how the resulting macroscopic strains and stresses are transferred across the scales down to the cellular and subcellular levels. Since cells anchor to the collagen fibres within the extracellular matrix, the reliable representation of fibre deformation is a prerequisite for models that aim at linking tissue biomechanics and cell mechanobiology. In this paper, we consider the two-scale mechanical response of an affine structural model as an example of a continuum mechanical approach and compare it with the results of a discrete fibre network model. In particular, we shed light on the crucially different mechanical properties of the ‘fibres’ in these two approaches. While assessing the capability of the affine structural approach to capture the fibre kinematics in real tissues is beyond the scope of our study, our results clearly show that neither the macroscopic tissue response nor the microscopic fibre orientation statistics can clarify the question of affinity.

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Comprehensive Identification of Tibiofemoral Joint Anatomy and Mechanical Response: Pathway to Multiscale Characterization

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80200 ◽

2012 ◽

Author(s):

Snehal Chokhandre ◽

Craig Bennetts ◽

Jason Halloran ◽

Robb Colbrunn ◽

Tara Bonner ◽

...

Keyword(s):

Knee Joint ◽

Mechanical Response ◽

Model Development ◽

Fe Analysis ◽

Tissue Response ◽

Tissue Properties ◽

Multiscale Mechanics ◽

Human Knee Joint

The human knee joint is a complex multi-body structure, whose substructures greatly affect its mechanical response. An understanding of the multiscale mechanics of the joint is essential for the prevention and treatment of knee joint injuries and pathologies. Due to the limitations associated with in vivo experimentation, mechanical characterization of the knee joint has commonly relied on in vitro experimentation [1,2]. Predictive and descriptive studies of the mechanical function of the knee and its substructures have commonly employed computational modeling, in particular finite element (FE) analysis, which can be driven by experimental data. With the recent focus on the use of FE models of the knee joint for scientific and clinical purposes [3–5], data for model development, verification, and validation became increasingly important, especially when relying on FE analysis for decision making. An adequate representation of a joint not only depends on the specimen-specific anatomy but may also need to be informed by specimen-specific tissue properties for model development, and specimen-specific joint/tissue response to confirm model response.

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The Hierarchic Order of Intermediate Filament Structure and Assembly

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120308 ◽

1985 ◽

Vol 43 ◽

pp. 722-725

Author(s):

U. Aebi ◽

E.C. Glavaris ◽

R. Eichner

Keyword(s):

Tissue Specificity ◽

Structural Model ◽

Eukaryotic Cells ◽

Cdna Sequencing ◽

Filament Structure ◽

Keratin Filaments ◽

Isoelectric Points ◽

Immunological Crossreactivity

Five different classes of intermediate-sized filaments (IFs) have been identified in differentiated eukaryotic cells: vimentin in mesenchymal cells, desmin in muscle cells, neurofilaments in nerve cells, glial filaments in glial cells and keratin filaments in epithelial cells. Despite their tissue specificity, all IFs share several common attributes, including immunological crossreactivity, similar morphology (e.g. about 10 nm diameter - hence ‘10-nm filaments’) and the ability to reassemble in vitro from denatured subunits into filaments virtually indistinguishable from those observed in vivo. Further more, despite their proteinchemical heterogeneity (their MWs range from 40 kDa to 200 kDa and their isoelectric points from about 5 to 8), protein and cDNA sequencing of several IF polypeptides (for refs, see 1,2) have provided the framework for a common structural model of all IF subunits.

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In vivo behavior of trimethylene carbonate and ε-caprolactone-based (co)polymer networks: Degradation and tissue response

Journal of Biomedical Materials Research Part A ◽

10.1002/jbm.a.32921 ◽

2010 ◽

Vol 95A (3) ◽

pp. 940-949 ◽

Cited By ~ 33

Author(s):

Erhan Bat ◽

Josée A. Plantinga ◽

Martin C. Harmsen ◽

Marja J. A. van Luyn ◽

Jan Feijen ◽

...

Keyword(s):

Polymer Networks ◽

Tissue Response ◽

Trimethylene Carbonate

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The Role of Mechanical Tension in Neurons

MRS Proceedings ◽

10.1557/proc-1274-qq01-06 ◽

2010 ◽

Vol 1274 ◽

Cited By ~ 1

Author(s):

Taher Saif ◽

Jagannathan Rajagopalan ◽

Alireza Tofangchi

Keyword(s):

Mechanical Response ◽

Mechanical Forces ◽

Active Tension ◽

Mechanical Tension ◽

Deformation Response ◽

Linear Force ◽

Tension Regulation ◽

Over Time

AbstractWe used high resolution micromechanical force sensors to study the in vivo mechanical response of embryonic Drosophila neurons. Our experiments show that Drosophila axons have a rest tension of a few nN and respond to mechanical forces in a manner characteristic of viscoelastic solids. In response to fast externally applied stretch they show a linear force-deformation response and when the applied stretch is held constant the force in the axons relaxes to a steady state value over time. More importantly, when the tension in the axons is suddenly reduced by releasing the external force the neurons actively restore the tension, sometimes close to their resting value. Along with the recent findings of Siechen et al (Proc. Natl. Acad. Sci. USA 106, 12611 (2009)) showing a link between mechanical tension and synaptic plasticity, our observation of active tension regulation in neurons suggest an important role for mechanical forces in the functioning of neurons in vivo.

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Improvement of biohistological response of facial implant materials by tantalum surface treatment

Maxillofacial Plastic and Reconstructive Surgery ◽

10.1186/s40902-019-0231-3 ◽

2019 ◽

Vol 41 (1) ◽

Author(s):

Mohammed Mousa Bakri ◽

Sung Ho Lee ◽

Jong Ho Lee

Keyword(s):

Foreign Body ◽

Soft Tissue ◽

Surface Treatment ◽

Clinical Applications ◽

Tissue Response ◽

Bone Surface ◽

Tissue Thickness ◽

Implant Materials ◽

Soft Tissue Thickness

Abstract Background A compact passive oxide layer can grow on tantalum (Ta). It has been reported that this oxide layer can facilitate bone ingrowth in vivo though the development of bone-like apatite, which promotes hard and soft tissue adhesion. Thus, Ta surface treatment on facial implant materials may improve the tissue response, which could result in less fibrotic encapsulation and make the implant more stable on the bone surface. The purposes of this study were to verify whether surface treatment of facial implant materials using Ta can improve the biohistobiological response and to determine the possibility of potential clinical applications. Methods Two different and commonly used implant materials, silicone and expanded polytetrafluoroethylene (ePTFE), were treated via Ta ion implantation using a Ta sputtering gun. Ta-treated samples were compared with untreated samples using in vitro and in vivo evaluations. Osteoblast (MG-63) and fibroblast (NIH3T3) cell viability with the Ta-treated implant material was assessed, and the tissue response was observed by placing the implants over the rat calvarium (n = 48) for two different lengths of time. Foreign body and inflammatory reactions were observed, and soft tissue thickness between the calvarium and the implant as well as the bone response was measured. Results The treatment of facial implant materials using Ta showed a tendency toward increased fibroblast and osteoblast viability, although this result was not statistically significant. During the in vivo study, both Ta-treated and untreated implants showed similar foreign body reactions. However, the Ta-treated implant materials (silicone and ePTFE) showed a tendency toward better histological features: lower soft tissue thickness between the implant and the underlying calvarium as well as an increase in new bone activity. Conclusion Ta surface treatment using ion implantation on silicone and ePTFE facial implant materials showed the possibility of reducing soft tissue intervention between the calvarium and the implant to make the implant more stable on the bone surface. Although no statistically significant improvement was observed, Ta treatment revealed a tendency toward an improved biohistological response of silicone and ePTFE facial implants. Conclusively, tantalum treatment is beneficial and has the potential for clinical applications.

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Somatostatin modulates cholinergic neurotransmission in canine antral muscle

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1988.254.2.g201 ◽

1988 ◽

Vol 254 (2) ◽

pp. G201-G209 ◽

Cited By ~ 1

Author(s):

C. B. Koelbel ◽

G. van Deventer ◽

S. Khawaja ◽

M. Mogard ◽

J. H. Walsh ◽

...

Keyword(s):

Electrical Stimulation ◽

Substance P ◽

Prostaglandin E2 ◽

Positive Inotropic Effect ◽

Mechanical Response ◽

Inhibitory Effect ◽

Inotropic Effect ◽

Inotropic Response ◽

Cholinergic Neurotransmission

Somatostatin has been shown to inhibit antral motility in vivo. To examine the effect of somatostatin on cholinergic neurotransmission in the canine antrum, we studied the mechanical response of and the release of [3H]acetylcholine from canine longitudinal antral muscle in response to substance P, gastrin 17, and electrical stimulation. In unstimulated tissues, somatostatin had a positive inotropic effect on spontaneous phasic contractions. In tissues stimulated with substance P and gastrin 17, but not with electrical stimulation, somatostatin inhibited the phasic inotropic response dose dependently. This inhibitory effect was abolished by indomethacin. Somatostatin stimulated the release of prostaglandin E2 radioimmunoreactivity, and prostaglandin E2 inhibited the release of [3H]acetylcholine induced by substance P and electrical stimulation. Somatostatin increased the release of [3H]acetylcholine from unstimulated tissues by a tetrodotoxin-sensitive mechanism but inhibited the release induced by substance P and electrical stimulation. These results suggest that somatostatin has a dual modulatory effect on cholinergic neurotransmission in canine longitudinal antral muscle. This effect is excitatory in unstimulated tissues and inhibitory in stimulated tissues. The inhibitory effect is partially mediated by prostaglandins.

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The Biological Effects of Combining Metals in a Posterior Spinal Implant: In Vivo Model Development Report of the First Two Cases

Advances in Orthopedic Surgery ◽

10.1155/2014/761967 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Christine L. Farnsworth ◽

Peter O. Newton ◽

Eric Breisch ◽

Michael T. Rohmiller ◽

Jung Ryul Kim ◽

...

Keyword(s):

Galvanic Corrosion ◽

Biological Effects ◽

Model Development ◽

Spinal Instrumentation ◽

Pedicle Screws ◽

Tissue Response ◽

In Vivo Model ◽

Particle Count ◽

Spinal Implant

Study Design. Combinations of metal implants (stainless steel (SS), titanium (Ti), and cobalt chrome (CC)) were placed in porcine spines. After 12 months, tissue response and implant corrosion were compared between mixed and single metal junctions. Objective. Model development and an attempt to determine any detriment of combining different metals in posterior spinal instrumentation. Methods. Yucatan mini-pigs underwent instrumentation over five unfused lumbar levels. A SS rod and a Ti rod were secured with Ti and SS pedicle screws, SS and Ti crosslinks, SS and CC sublaminar wires, and Ti sublaminar cable. The resulting 4 SS/SS, 3 Ti/Ti, and 11 connections between dissimilar metals per animal were studied after 12 months using radiographs, gross observation, and histology (foreign body reaction (FBR), metal particle count, and inflammation analyzed). Results. Two animals had constructs in place for 12 months with no complications. Histology of tissue over SS/SS connections demonstrated 11.1 ± 7.6 FBR cells, 2.1 ± 1.7 metal particles, and moderate to extensive inflammation. Ti/Ti tissue showed 6.3 ± 3.8 FBR cells, 5.2 ± 6.7 particles, and no to extensive inflammation (83% extensive). Tissue over mixed components had 14.1 ± 12.6 FBR cells and 13.4 ± 27.8 particles. Samples surrounding wires/cables versus other combinations demonstrated FBR (12.4 ± 13.5 versus 12.0 ± 9.6 cells, P = 0.96), particles (19.8 ± 32.6 versus 4.3 ± 12.7, P = 0.24), and inflammation (50% versus 75% extensive, P = 0.12). Conclusions. A nonfusion model was developed to study corrosion and analyze biological responses. Although no statistical differences were found in overlying tissue response to single versus mixed metal combinations, galvanic corrosion between differing metals is not ruled out. This pilot study supports further investigation to answer concerns when mixing metals in spinal constructs.

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Structural model of the gas vesicle protein GvpA and analysis of GvpA mutants in vivo

Molecular Microbiology ◽

10.1111/j.1365-2958.2011.07669.x ◽

2011 ◽

Vol 81 (1) ◽

pp. 56-68 ◽

Cited By ~ 26

Author(s):

Timo Strunk ◽

Kay Hamacher ◽

Franziska Hoffgaard ◽

Harald Engelhardt ◽

Martina Daniela Zillig ◽

...

Keyword(s):

Structural Model ◽

Vesicle Protein

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Dependence of Mechanical Behavior of the Murine Tail Disc on Regional Material Properties: A Parametric Finite Element Study

Journal of Biomechanical Engineering ◽

10.1115/1.2073467 ◽

2005 ◽

Vol 127 (7) ◽

pp. 1158-1167 ◽

Cited By ~ 26

Author(s):

Adam H. Hsieh ◽

Diane R. Wagner ◽

Louis Y. Cheng ◽

Jeffrey C. Lotz

Keyword(s):

Finite Element ◽

Mechanical Behavior ◽

Nucleus Pulposus ◽

Material Properties ◽

Mechanical Response ◽

Swelling Pressure ◽

Transient Behavior ◽

Sensitivity Analyses ◽

Intact Mouse

In vivo rodent tail models are becoming more widely used for exploring the role of mechanical loading on the initiation and progression of intervertebral disc degeneration. Historically, finite element models (FEMs) have been useful for predicting disc mechanics in humans. However, differences in geometry and tissue properties may limit the predictive utility of these models for rodent discs. Clearly, models that are specific for rodent tail discs and accurately simulate the disc’s transient mechanical behavior would serve as important tools for clarifying disc mechanics in these animal models. An FEM was developed based on the structure, geometry, and scale of the mouse tail disc. Importantly, two sources of time-dependent mechanical behavior were incorporated: viscoelasticity of the matrix, and fluid permeation. In addition, a novel strain-dependent swelling pressure was implemented through the introduction of a dilatational stress in nuclear elements. The model was then validated against data from quasi-static tension-compression and compressive creep experiments performed previously using mouse tail discs. Finally, sensitivity analyses were performed in which material parameters of each disc subregion were individually varied. During disc compression, matrix consolidation was observed to occur preferentially at the periphery of the nucleus pulposus. Sensitivity analyses revealed that disc mechanics was greatly influenced by changes in nucleus pulposus material properties, but rather insensitive to variations in any of the endplate properties. Moreover, three key features of the model—nuclear swelling pressure, lamellar collagen viscoelasticity, and interstitial fluid permeation—were found to be critical for accurate simulation of disc mechanics. In particular, collagen viscoelasticity dominated the transient behavior of the disc during the initial 2200s of creep loading, while fluid permeation governed disc deformation thereafter. The FEM developed in this study exhibited excellent agreement with transient creep behavior of intact mouse tail motion segments. Notably, the model was able to produce spatial variations in nucleus pulposus matrix consolidation that are consistent with previous observations in nuclear cell morphology made in mouse discs using confocal microscopy. Results of this study emphasize the need for including nucleus swelling pressure, collagen viscoelasticity, and fluid permeation when simulating transient changes in matrix and fluid stress/strain. Sensitivity analyses suggest that further characterization of nucleus pulposus material properties should be pursued, due to its significance in steady-state and transient disc mechanical response.

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