scholarly journals Strain amplification in bone mechanobiology: a computational investigation of the in vivo mechanics of osteocytes

2012 ◽  
Vol 9 (75) ◽  
pp. 2735-2744 ◽  
Author(s):  
Stefaan W. Verbruggen ◽  
Ted J. Vaughan ◽  
Laoise M. McNamara
Keyword(s):  
Computational Models ◽  
Bone Growth ◽  
Bone Cells ◽  
Physiological Activity ◽  
Three Dimensional ◽  
Mechanical Stimulus ◽  
Confocal Imaging ◽  
Mechanical Stimuli ◽  
Confocal Image

The osteocyte is believed to act as the main sensor of mechanical stimulus in bone, controlling signalling for bone growth and resorption in response to changes in the mechanical demands placed on our bones throughout life. However, the precise mechanical stimuli that bone cells experience in vivo are not yet fully understood. The objective of this study is to use computational methods to predict the loading conditions experienced by osteocytes during normal physiological activities. Confocal imaging of the lacunar–canalicular network was used to develop three-dimensional finite element models of osteocytes, including their cell body, and the surrounding pericellular matrix (PCM) and extracellular matrix (ECM). We investigated the role of the PCM and ECM projections for amplifying mechanical stimulation to the cells. At loading levels, representing vigorous physiological activity (3000 µ ɛ ), our results provide direct evidence that (i) confocal image-derived models predict 350–400% greater strain amplification experienced by osteocytes compared with an idealized cell, (ii) the PCM increases the cell volume stimulated more than 3500 µ ɛ by 4–10% and (iii) ECM projections amplify strain to the cell by approximately 50–420%. These are the first confocal image-derived computational models to predict osteocyte strain in vivo and provide an insight into the mechanobiology of the osteocyte.

Fluid-Structure Interaction Modelling Predicts That Strain Transfer Through Focal Attachments of Osteoblast Cells are the Primary Mediators of Mechanical Stimulation Under Fluid Flow

2013 ◽  
Author(s):  
T. J. Vaughan ◽  
M. G. Haugh ◽  
L. M. McNamara
Keyword(s):  
Fluid Flow ◽  
Mechanical Stimulation ◽  
Interstitial Fluid ◽  
Bone Cells ◽  
Mechanical Stimulus ◽  
Mechanical Stimuli ◽  
Interstitial Fluid Flow ◽  
Interaction Modelling

Bone continuously adapts its internal structure to accommodate the functional demands of its mechanical environment. It has been proposed that indirect strain-induced flow of interstitial fluid surrounding bone cells may be the primary mediator of mechanical stimuli in-vivo [1]. Due to the practical difficulties in ascertaining whether interstitial fluid flow is indeed the primary mediator of mechanical stimuli in the in vivo environment, much of the evidence supporting this theory has been established through in vitro investigations that have observed cellular activity in response to fluid flow imposed by perfusion chambers [2]. While such in vitro experiments have identified key mechanisms involved in the mechanotransduction process, the exact mechanical stimulus being imparted to cells within a monolayer is unknown [3]. Furthermoreit is not clear whether the mechanical stimulation is comparable between different experimental systems or, more importantly, is representative of physiological loading conditions experienced by bone cells in vivo.

Loading-Induced Interstitial Fluid Flow in Bone Mechanobiology: An FSI Approach to the Osteocyte Environment

2012 ◽  
Author(s):  
Stefaan W. Verbruggen ◽  
Ted J. Vaughan ◽  
Laoise M. McNamara
Keyword(s):  
Adaptive Response ◽  
Interstitial Fluid ◽  
Bone Growth ◽  
Mechanical Stimulus ◽  
Mechanical Stimuli ◽  
Interstitial Fluid Flow ◽  
Physiological Demands ◽  
Control Bone ◽  
Ubiquitous Presence

Bone is an adaptive material, which is particularly responsive to mechanical loading and can adapt its mass and structure to meet the mechanical demands experienced throughout life. The osteocyte, due to its ubiquitous presence throughout bone, is believed to act as the main sensor of mechanical stimulus in bone, recruiting other cells to control bone growth and resorption in response to changes in physiological demands. However the precise mechanical stimuli that osteocytes experience in vivo, and what type of stimulus instigates an adaptive response, are not fully understood.

scholarly journals Prediction of Aerosol Deposition in the Human Respiratory Tract via Computational Models: A Review with Recent Updates

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 137 ◽  
Author(s):  
Vu Khac Hoang Bui ◽  
Ju-Young Moon ◽  
Minhe Chae ◽  
Duckshin Park ◽  
Young-Chul Lee
Keyword(s):  
Respiratory Tract ◽  
Particle Deposition ◽  
Computational Models ◽  
Aerosol Particles ◽  
Three Dimensional ◽  
Aerosol Deposition ◽  
Research Area ◽  
Human Respiratory Tract

The measurement of deposited aerosol particles in the respiratory tract via in vivo and in vitro approaches is difficult due to those approaches’ many limitations. In order to overcome these obstacles, different computational models have been developed to predict the deposition of aerosol particles inside the lung. Recently, some remarkable models have been developed based on conventional semi-empirical models, one-dimensional whole-lung models, three-dimensional computational fluid dynamics models, and artificial neural networks for the prediction of aerosol-particle deposition with a high accuracy relative to experimental data. However, these models still have some disadvantages that should be overcome shortly. In this paper, we take a closer look at the current research trends as well as the future directions of this research area.

Evaluation and Control of Crystallographic Alignment of Biological Apatite Crystallites in Bones

2010 ◽  
Vol 654-656 ◽  
pp. 2212-2215
Author(s):  
Takayoshi Nakano ◽  
Takuya Ishimoto ◽  
Jee Wook Lee ◽  
Sayaka Miyabe ◽  
Naoko Ikeo ◽  
...  
Keyword(s):  
Bone Growth ◽  
Bone Cells ◽  
Quality Parameter ◽  
Gene Defect ◽  
Axis Orientation ◽  
Biological Apatite ◽  
Microstructural Anisotropy ◽  
And Control ◽  
Preferential Alignment

Our group focused on the preferential degree of biological apatite (BAp) c-axis, an important bone quality parameter based on the microstructural anisotropy in intact, pathological, and regenerated bones. The preferential degree of the BAp c-axis strongly depends on the bone position, in vivo stress distribution, bone growth, degree of pathology and regeneration, activity of bone cells, gene defect, etc. We attempted to challenge clarification of the BAp preferential alignment formation mechanism and control the degree of BAp orientation by using an anisotropic biomaterial design to develop suitable distribution of the BAp c-axis orientation.

Noninvasive In Vivo Characterization of Pediatric Human Spine: 3-D Finite Element Study

2011 ◽  
Author(s):  
Elizabeth S. Doughty ◽  
Nesrin Sarigul-Klijn
Keyword(s):  
Finite Element ◽  
Computational Model ◽  
Muscle Activation ◽  
Computational Models ◽  
Three Dimensional ◽  
Pediatric Spine ◽  
Element Analysis ◽  
Spine Stabilization ◽  
Surgical Tool

There are no full three-dimensional computational models of the pediatric spine to study the many diseases and disorders that afflict the immature spine using finite element analysis. To fully characterize the pediatric spine, we created a pediatric specific computational model of C1-L5 using noninvasive in vivo techniques to incorporate the differences between the adult and pediatric spines: un-fused vertebrae, lax ligaments, and higher water content in the intervertebral discs. Muscle follower loads were included in the model to simulate muscle activation for five muscles involved in spine stabilization. This paper is the first pediatric three-dimensional model developed to date. Due to a lack of experimental pediatric spinal studies, this 3-D computational model has the potential to become a surgical tool to ensure that the most appropriate technique is chosen for treating pediatric spinal dysfunctions such as congenital abnormalities, idiopathic scoliosis, and vertebral fractures.

scholarly journals Noninvasive Pigment Identification in Single Cells from Living Phototrophic Biofilms by Confocal Imaging Spectrofluorometry

2004 ◽  
Vol 70 (6) ◽  
pp. 3745-3750 ◽  
Author(s):  
M. Rold�n ◽  
F. Thomas ◽  
S. Castel ◽  
A. Quesada ◽  
M. Hern�ndez-Marin�
Keyword(s):  
Single Cells ◽  
Three Dimensional ◽  
Confocal Imaging ◽  
Confocal Scanning Laser Microscopy ◽  
Pigment Analysis ◽  
Phototrophic Biofilms ◽  
Scanning Laser Microscopy ◽  
Confocal Scanning ◽  
Confocal Scanning Laser

ABSTRACT A new imaging technique for the analysis of fluorescent pigments from a single cell is reported. It is based on confocal scanning laser microscopy coupled with spectrofluorometric methods. The setup allows simultaneous establishment of the relationships among pigment analysis in vivo, morphology, and three-dimensional localization inside thick intact microbial assemblages.

scholarly journals 3-D Volumetric Evaluation of Human Mandibular Growth

2011 ◽  
Vol 5 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Mathew Reynolds ◽  
Michael Reynolds ◽  
Samer Adeeb ◽  
Tarek El-Bialy
Keyword(s):  
Bone Growth ◽  
Three Dimensional ◽  
Mandibular Growth ◽  
Virtual Models ◽  
Complex Process ◽  
Simple Basis ◽  
Marker Studies ◽  
One Year ◽  
Reported Data

Bone growth is a complex process that is controlled by a multitude of mechanisms that are not fully understood.Most of the current methods employed to measure the growth of bones focus on either studying cadaveric bones from different individuals of different ages, or successive two-dimensional (2D) radiographs. Both techniques have their known limitations. The purpose of this study was to explore a technique for quantifying the three dimensional (3D) growth of an adolescent human mandible over the period of one year utilizing cone beam computed tomography (CBCT) scans taken for regular orthodontic records. Three -dimensional virtual models were created from the CBCT data using mainstream medical imaging software. A comparison between computer-generated surface meshes of successive 3-D virtual models illustrates the magnitude of relative mandible growth. The results of this work are in agreement with previously reported data from human cadaveric studies and implantable marker studies. The presented method provides a new relatively simple basis (utilizing commercially available software) to visualize and evaluate individualized 3D (mandibular) growth in vivo.

scholarly journals Evaluation of a modified Cheatham-Platinum stent for the treatment of aortic coarctation by finite element modelling

2018 ◽  
Vol 7 ◽  
pp. 204800401877395 ◽  
Author(s):  
Barbara EU Burkhardt ◽  
Nicholas Byrne ◽  
Marí Nieves Velasco Forte ◽  
Francesco Iannaccone ◽  
Matthieu De Beule ◽  
...  
Keyword(s):  
Finite Element ◽  
Aortic Coarctation ◽  
Computational Models ◽  
Three Dimensional ◽  
Computational Modelling ◽  
Patient Specific ◽  
Stent Design ◽  
Initial Length ◽  
Element Analysis

Objectives Stent implantation for the treatment of aortic coarctation has become a standard approach for the management of older children and adults. Criteria for optimal stent design and construction remain undefined. This study used computational modelling to compare the performance of two generations of the Cheatham-Platinum stent (NuMED, Hopkinton, NY, USA) deployed in aortic coarctation using finite element analysis. Design Three-dimensional models of both stents, reverse engineered from microCT scans, were implanted in the aortic model of one representative patient. They were virtually expanded in the vessel with a 16 mm balloon and a pressure of 2 atm. Results The conventional stent foreshortened to 96.5% of its initial length, whereas the new stent to 99.2% of its initial length. Diameters in 15 slices across the conventional stent were 11.6–15 mm (median 14.2 mm) and slightly higher across the new stent: 10.7–15.3 mm (median 14.5 mm) (p= 0.021). Apposition to the vessel wall was similar: conventional stent 31.1% and new stent 28.6% of total stent area. Conclusions The new design Cheatham-Platinum stent showed similar deployment results compared to the conventional design. The new stent design showed slightly higher expansion, using the same delivery balloon. Patient-specific computational models can be used for virtual implantation of new aortic stents and promise to inform subsequent in vivo trials.

scholarly journals Sex-dependent differences in central artery haemodynamics in normal and fibulin-5 deficient mice: implications for ageing

2019 ◽  
Vol 475 (2221) ◽  
pp. 20180076 ◽  
Author(s):  
Federica Cuomo ◽  
Jacopo Ferruzzi ◽  
Pradyumn Agarwal ◽  
Chen Li ◽  
Zhen W. Zhuang ◽  
...  
Keyword(s):  
Computational Models ◽  
Pulse Wave ◽  
Three Dimensional ◽  
Micro Computed Tomography ◽  
Central Artery ◽  
Wall Stiffness ◽  
Outflow Boundary ◽  
Deficient Mice

Mouse models provide unique opportunities to study vascular disease, but they demand increased experimental and computational resolution. We describe a workflow for combining in vivo and in vitro biomechanical data to build mouse-specific computational models of the central vasculature including regional variations in biaxial wall stiffness, thickness and perivascular support. These fluid–solid interaction models are informed by micro-computed tomography imaging and in vivo ultrasound and pressure measurements, and include mouse-specific inflow and outflow boundary conditions. Hence, the model can capture three-dimensional unsteady flows and pulse wave characteristics. The utility of this experimental–computational approach is illustrated by comparing central artery biomechanics in adult wild-type and fibulin-5 deficient mice, a model of early vascular ageing. Findings are also examined as a function of sex. Computational results compare well with measurements and data available in the literature and suggest that pulse wave velocity, a spatially integrated measure of arterial stiffness, does not reflect well the presence of regional differences in stiffening, particularly those manifested in male versus female mice. Modelling results are also useful for comparing quantities that are difficult to measure or infer experimentally, including local pulse pressures at the renal arteries and characteristics of the peripheral vascular bed that may differ with disease.

scholarly journals A fluid–structure interaction model to characterize bone cell stimulation in parallel-plate flow chamber systems

2013 ◽  
Vol 10 (81) ◽  
pp. 20120900 ◽  
Author(s):  
T. J. Vaughan ◽  
M. G. Haugh ◽  
L. M. McNamara
Keyword(s):  
Shear Stress ◽  
Fluid Flow ◽  
Parallel Plate ◽  
Bone Cells ◽  
Mechanical Stimulus ◽  
Flow Chamber ◽  
Parallel Plate Flow Chamber ◽  
Structure Interaction

Bone continuously adapts its internal structure to accommodate the functional demands of its mechanical environment and strain-induced flow of interstitial fluid is believed to be the primary mediator of mechanical stimuli to bone cells in vivo. In vitro investigations have shown that bone cells produce important biochemical signals in response to fluid flow applied using parallel-plate flow chamber (PPFC) systems. However, the exact mechanical stimulus experienced by the cells within these systems remains unclear. To fully understand this behaviour represents a most challenging multi-physics problem involving the interaction between deformable cellular structures and adjacent fluid flows. In this study, we use a fluid–structure interaction computational approach to investigate the nature of the mechanical stimulus being applied to a single osteoblast cell under fluid flow within a PPFC system. The analysis decouples the contribution of pressure and shear stress on cellular deformation and for the first time highlights that cell strain under flow is dominated by the pressure in the PPFC system rather than the applied shear stress. Furthermore, it was found that strains imparted on the cell membrane were relatively low whereas significant strain amplification occurred at the cell–substrate interface. These results suggest that strain transfer through focal attachments at the base of the cell are the primary mediators of mechanical signals to the cell under flow in a PPFC system. Such information is vital in order to correctly interpret biological responses of bone cells under in vitro stimulation and elucidate the mechanisms associated with mechanotransduction in vivo .

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