Actin stress fibers (SFs), a contractile apparatus in nonmuscle cells, possess a contractile unit that is apparently similar to the sarcomere of myofibrils in muscles. The function of SFs has thus often been addressed based on well-characterized properties of muscles. However, unlike the fixed number of myosin molecules in myofibrils, the number of nonmuscle myosin II (NMII) within the contractile

Amoeboid cells often migrate using pseudopods, which are membrane protrusions that grow, bifurcate, and retract dynamically, resulting in a net cell displacement. Many cells within the human body, such as immune cells, epithelial cells, and even metastatic cancer cells, can migrate using the amoeboid phenotype. Amoeboid motility is a complex and multiscale process, where cell deformation, biochemistry

Ischemic mitral regurgitation (IMR), a frequent complication of myocardial infarction, is characterized by regurgitation of blood from the left ventricle back into the left atrium. Physical interventions via surgery or less-invasive techniques are the only available therapies for IMR, with valve repair via undersized ring annuloplasty (URA) generally preferred over valve replacement. However, recurrence

Vascular stenting is a common intervention for the treatment for atherosclerotic plaques. However, stenting still has a significant rate of restenosis caused by intimal hyperplasia formation. In this study, we evaluate whether stent overexpansion leads to Vasa Vasorum (VV) compression, which may contribute to vascular wall hypoxia and restenosis. An idealized multilayered fibroatheroma model including

The compliance of the proximal aortic wall is a major determinant of cardiac afterload. Aortic compliance is often estimated based on cross-sectional area changes over the pulse pressure, under the assumption of a negligible longitudinal stretch during the pulse. However, the proximal aorta is subjected to significant axial stretch during cardiac contraction. In the present study, we sought to evaluate

Revealing the mechanisms underlying the intracellular calcium responses in vascular endothelial cells (VECs) induced by mechanical stimuli contributes to a better understanding for vascular diseases, including hypertension, atherosclerosis, and aneurysm. Combining with experimental measurement and Computational Fluid Dynamics simulation, we developed a mechanobiological model to investigate the intracellular

The artery relies on interlamellar structural components, mainly elastin and collagen fibers, for maintaining its integrity and resisting dissection propagation. In this study, the contribution of arterial elastin and collagen fibers to interlamellar bonding was studied through mechanical testing, multiphoton imaging and finite element modeling. Steady-state peeling experiments were performed on porcine

Performing physiologically relevant simulations of the beating heart in clinical context requires to develop detailed models of the microscale force generation process. These models, however, may reveal difficult to implement in practice due to their high computational costs and complex calibration. We propose a hierarchy of three interconnected muscle contraction models—from the more refined to the

Many biomedical, orthopaedic, and industrial applications are emerging that will benefit from personalized neuromusculoskeletal models. Applications include refined diagnostics, prediction of treatment trajectories for neuromusculoskeletal diseases, in silico design, development, and testing of medical implants, and human–machine interfaces to support assistive technologies. This review proposes how

Vesiculation is a ubiquitous process undergone by most cell types and serves a variety of vital cell functions; vesiculation from erythrocytes, in particular, is a well-known example and constitutes a self-protection mechanism against premature clearance, inter alia. Herein, we explore a paradigm that red blood cell derived vesicles may form within the microvascular, in intense shear flow, where cells

A continuous model for the peristaltic locomotion of compressible and incompressible rod-like bodies is presented. Using Green and Naghdi’s theory of a directed rod, incompressibility is enforced as an internal constraint. A discussion on muscle actuation models for a single continuum is included. The resulting theory is demonstrated in a simulation of a soft-robotic device. In addition, a calibration

We propose a mechanical model of generation of vitreoretinal tractions in the presence of posterior vitreous detachment (PVD). PVD is a common occurrence with aging, and it consists in the separation of the vitreous body from the retina at the back pole of the eye, due to progressive shrinking of the vitreous gel. During this separation process, vitreoretinal tractions are generated at regions of high

In this paper, we extend the model of wound healing by Boon et al. (J Biomech 49(8):1388–1401, 2016). In addition to explaining the model explicitly regarding every component, namely cells, signalling molecules and tissue bundles, we categorized fibroblasts as regular fibroblasts and myofibroblasts. We do so since it is widely documented that myofibroblasts play a significant role during wound healing

Bone remodeling is a fundamental biological process that develops in bone tissue along its whole lifetime. It refers to a continuous bone transformation with new bone formation and old bone resorption that changes the internal microstructure and composition of the tissue. The main objectives of bone remodeling are: repair of the internal microcracks; adaptation of the macroscopic stiffness and strength

Aortic dissection (AD) is one of the most catastrophic cardiovascular diseases. AD occurs when a layer inside the aorta is disrupted and gives rise to the formation of a true lumen and a false lumen. These lumens can be connected through tears in the intimal flap which are known as entries. Despite being known for about two centuries, the effects of many factors on the morbidity and mortality of this

The immersed boundary method (IBM) has been frequently utilized to simulate the motion and deformation of biological cells and capsules in various flow situations. Despite the convenience in dealing with flow-membrane interaction, direct implementation of membrane viscosity in IBM suffers severe numerical instability. It has been shown that adding an artificial elastic element in series to the viscous

A computational strategy based on the finite element method for simulating the mechanical response of arterial tissues is herein proposed. The adopted constitutive formulation accounts for rotations of the adventitial collagen fibers and introduces parameters which are directly measurable or well established. Moreover, the refined constitutive model is readily utilized in finite element analyses, enabling

In this paper, we proposed a two-state model to quantitatively illustrate the working mechanism of caveolae structure in the regulation of cell membrane stretch. First, we derived the free energy compositions of one caveola in an arbitrary state. This model predicts two local minima for the free energy of one caveola at the completely open and completely closed states at the bottom of a relatively

A nonlinear viscoelastic model for the lung is implemented and evaluated for high-rate loading. Principal features of the model include a closed-cell approximation of the bulk compressibility accounting for air inside the lung and a damage-injury component by which local trauma is induced by cumulative normalized internal energy and amplified by gradients of energy density. The latter feature is adapted

In the original publication of the article.

Menisci are fibrocartilaginous disks consisting of soft tissue with a complex biomechanical structure. They are critical determinants of the kinematics as well as the stability of the knee joint. Several studies have been carried out to formulate tissue mechanical behavior, leading to the development of a wide spectrum of constitutive laws. In addition to developing analytical tools, extensive numerical

Instability and dislocation remain leading indications for revision of total hip arthroplasty (THA). Many studies have addressed the links between implant design and dislocation; however, an understanding of the impact of alignment and kinematic variability on constraint of modern THA constructs to provide joint stability is needed. The objective of this study is to provide objective data to be considered

Fluorescence recovery after photobleaching (FRAP) is a widely used technique for studying diffusion in biological tissues. Most of the existing approaches for the analysis of FRAP experiments assume isotropic diffusion, while only a few account for anisotropic diffusion. In fibrous tissues, such as articular cartilage, tendons and ligaments, diffusion, the main mechanism for molecular transport, is

The contribution presents an extension and application of a recently proposed finite element formulation for quasi-inextensible and quasi-incompressible finite hyperelasticity to fibrous soft biological tissues and touches in particular upon computational aspects thereof. In line with theoretical framework presented by Dal (Int J Numer Methods Eng 117:118–140, 2019), the mixed variational formulation

Wrinkling is a ubiquitous surface phenomenon in many biological tissues and is believed to play an important role in arterial health. As arteries are highly nonlinear, anisotropic, multilayered composite systems, it is necessary to investigate wrinkling incorporating these material characteristics. Several studies have examined surface wrinkling mechanisms with nonlinear isotropic material relationships

Bridging veins (BVs) drain the blood from the cerebral cortex into dural sinuses. BVs have one end attached to the brain and the other to the superior sagittal sinus (SSS), which is attached to the skull. Relative movement between these two structures can cause BV to rupture producing acute subdural haematoma, a head injury with a mortality rate between 30 and 90%. A clear understanding of the BVs

We present a novel patient-specific fluid-solid-growth framework to model the mechanobiological state of clinically detected intracranial aneurysms (IAs) and their evolution. The artery and IA sac are modeled as thick-walled, non-linear elastic fiber-reinforced composites. We represent the undulation distribution of collagen fibers: the adventitia of the healthy artery is modeled as a protective sheath

In bone fracture healing, new tissue gradually forms, ossifies, and eventually remodels itself to restore mechanical stiffness and strength across injury site. Mechanical strain at the fracture site has been implicated in controlling the process of healing and numerical mechanoregulation models with strain-based fuzzy logic rules have been applied to simulate bone healing for simple fracture geometries

A micromechanical analysis is offered for the prediction of the global behavior of biological tissues. The analysis is based on the isotropic–hyperelastic behavior of the individual constituents (Collagen and Elastin), their volume fractions, and takes into account their detailed interactions. The present analysis predicts the instantaneous tensors from which the effective current first tangent tensor

The in silico simulations are widely used in contemporary systems biology including the analysis of nerve pulse propagation. As known from numerous experiments, the propagation of an action potential is accompanied by mechanical and thermal effects. This calls for an analysis at the interface of physics, physiology and mathematics. In this paper, the background of the model equations governing the

Repairing critical-size bone defects with engineered scaffolds remains a challenge in orthopedic practice. Insufficient vascularization is a major reason causing the failure of bone regeneration within scaffolds. Loading exogenous vascular endothelial growth factor (VEGF) in biodegradable polymer scaffolds and controlling its release rate can promote vascularization in scaffolds and accelerate bone

The minor type IV collagen chain, which is a significant component of the glomerular basement membrane in healthy individuals, is known to assemble into large structures (supercoils) that may contribute to the mechanical stability of the collagen network and the glomerular basement membrane as a whole. The absence of the minor chain, as in Alport syndrome, leads to glomerular capillary demise and eventually

Every group of microorganism utilizes a diverse mechanical strategy to propel through complex environments. These swimming problems deal with the fluid-organism interaction at micro-scales in which Reynolds number is of the order of 10-3. By adopting the same propulsion mechanism of so-called Taylor's sheet, here we address the biomechanical principle of swimming via different wavy surfaces. The passage

There lacks a comprehensive understanding of the correlation between head kinematics and brain strain especially deep-brain strain, partially resulting the deficiency of understanding brain injury mechanisms and the difficulty of choosing appropriate brain injury metrics. Hence, we simulated 76 impacts that were focused on concussion-relevant rotational kinematics and evaluated cumulative strain damage

Finite element human body models (HBMs) are used to assess injury risk in a variety of impact scenarios. The ribs are a key structural component within the chest, so their accuracy within HBMs is vitally important for modeling human biomechanics. We assessed the geometric correspondence between the ribs defined within five widely used HBMs and measures drawn from population-wide studies of rib geometry

The malfunctioning of semicircular canals (SCCs) in the vestibular system results in diseases that disrupt the individual's daily life. Vestibular diseases can be treated more effectively if the functioning of the SCCs is better understood. However, the SCC is difficult to dissect, because it is a complex structure buried deep in the inner ear. To thoroughly understand the function of SCCs and provide

Magnetic drug delivery as a potential method to treat diseases such as cancer tumors has attracted the attention of many researchers. One of the problems in conventional and ineffective therapies is the spread of drug in the circulatory system. The method of magnetic drug delivery aims at directing the drug to the localized area of disease by using a magnetic field. Considering the effects of parameters

The extracellular matrix (ECM) comprises a large proportion of the lung parenchymal tissue and is an important contributor to the mechanical properties of the lung. The lung tissue is a biologically active scaffold with a complex ECM matrix structure and composition that provides physical support to the surrounding cells. Nearly all respiratory pathologies result in changes in the structure and composition

The coated porous section of stem surface is initially filled with callus that undergoes osseointegration process, which develops a bond between stem and bone, lessens the micromotions and transfers stresses to the bone, proximally. This phenomenon attributes to primary and secondary stabilities of the stems that exhibit trade-off the stem stiffness. This study attempts to ascertain the influence of

The ability to measure bone tissue material properties plays a major role in diagnosis of diseases and material modeling. Bone's response to loading is complex and shows a viscous contribution to stiffness, yield and failure. It is also ductile and damaging and exhibits plastic hardening until failure. When performing mechanical tests on bone tissue, these constitutive effects are difficult to quantify

Lower urinary tract dysfunction pertains to symptoms related to the lower urinary tract (LUT), with consequent incontinence. Artificial urinary sphincters (AUS) are adopted to obtain continence conditions, mainly in male subjects, via urethral occlusion by applying pressure load, mostly operating on the basis of an empirical approach. Considering the frequent access of elderly patients to this surgical

It is widely accepted that biomechanics plays an important role in glaucoma pathophysiology, but the mechanisms involved are largely unknown. Rats are a common animal model of glaucoma, and finite element models are being developed to provide much-needed insight into the biomechanical environment of the posterior rat eye. However, material properties of rat ocular tissues, including the sclera, are

Cardiac growth is an important mechanism for the human body to respond to changes in blood flow demand. Being able to predict the development of chronic growth is clinically relevant, but so far models to predict growth have not reached consensus on the stimulus-effect relation. In a previously published study, we modeled cardiac and hemodynamic function through a lumped parameter approach. We evaluated

A mechanical model is presented to analyze the mechanics and dynamics of the cell cortex during indentation. We investigate the impact of active contraction on the cross-linked actin network for different probe sizes and indentation rates. The essential molecular mechanisms of filament stretching, cross-linking and motor activity, are represented by an active and viscous mechanical continuum. The filaments

Finite element (FE) modeling is becoming increasingly prevalent in the world of cardiac mechanics; however, many existing FE models are phenomenological and thus do not capture cellular-level mechanics. This work implements a cellular-level contraction scheme into an existing nonlinear FE code to model ventricular contraction. Specifically, this contraction model incorporates three myosin states: OFF-

On March 11, 2020, the World Health Organization declared the coronavirus disease 2019, COVID-19, a global pandemic. In an unprecedented collective effort, massive amounts of data are now being collected worldwide to estimate the immediate and long-term impact of this pandemic on the health system and the global economy. However, the precise timeline of the disease, its transmissibility, and the effect

Cancer progression involves biomechanical changes within transformed cells and the surrounding extracellular matrix (ECM). The viscoelastic features of fluidity and elasticity that are based on a novel Kelvin-Voigt fractional derivative (KVFD) model were found capable of discriminating normal, benign and malignant breast biopsy tissues on the cellular scale. The improved specificity of KVFD model parameters

In this study, 3D finite element analyses (FEA) are conducted to quantify the orthotropic elastic properties and investigate the load transfer mechanism of bone at the sub-lamellar level. Three finite element (FE) unit cells with periodic boundary conditions are presented to model a two-scale microstructure of bone including a mineralized collagen fibril (MCF), the extrafibrillar matrix (EFM) and the

The load distribution among lumbar spinal structures-still an unanswered question-has been in the focus of this hybrid experimental and simulation study. First, the overall passive resistive torque-angle characteristics of healthy subjects' lumbar spines during flexion-extension cycles in the sagittal plane were determined experimentally by use of a custom-made trunk-bending machine. Second, a forward

A three-dimensional finite-element fluid/structure interaction model of an intravascular lymphatic valve was constructed, and its properties were investigated under both favourable and adverse pressure differences, simulating valve opening and valve closure, respectively. The shear modulus of the neo-Hookean material of both vascular wall and valve leaflet was varied, as was the degree of valve opening

This is to inform that the original article was published without the "Conflict of Interest" statement.

In the published paper, we argued that, although there appear to be no data available on the subject, it is inherently unlikely that lymph having traversed a network of initial lymphatics and pre-collectors then encounters an abrupt transition to vessels with all of the typical properties of collecting lymphatics.

A mechanics-based mathematical model of retinal detachment due to the geometric changes of the eye associated with the evolution of myopia is developed. This includes deformation of the retina due to biological growth of the retina, as well as elastic deformation imposed on the retina by the myopic change in shape of the much stiffer choroid and sclera. The problem is formulated as a propagating boundary

Endothelial cells (ECs) play a major role in the healing process following angioplasty to inhibit excessive neointima. This makes the process of EC healing after injury, in particular EC migration in a stented vessel, important for recovery of normal vessel function. In that context, we present a novel particle-based model of EC migration and validate it against in vitro experimental data. We have

During morphogenesis in development, multicellular tissues deform by mechanical forces induced by spatiotemporally regulated cellular activities, such as cell proliferation and constriction. Various morphologies are formed because of various spatiotemporal combinations and sequences of multicellular activities. Despite its potential to variations, morphogenesis is a surprisingly robust process, in

Proximal femoral deformities can result from altered hip joint loading patterns during growth. The growth plate hyaline cartilage has low resistance to shear stress. Therefore, we hypothesized that the growth plate orients in a direction which minimizes the shear stress on its surface. A finite element model of the proximal femur was generated with a simplified flat growth plate. Hip joint forces were

Transcatheter aortic valve implantation (TAVI) is currently recommended in practice guidelines for patients who are at intermediate to high surgical risk for surgical aortic valve replacement. Coronary artery obstruction is a fatal complication of TAVI that occurs in up to 3.5% of the implantations inside a failed surgical bioprosthetic valve (valve-in-valve, ViV). A new technique to address this problem

In many fiber-reinforced tissues, collagen fibers are embedded within a glycosaminoglycan-rich extrafibrillar matrix. Knowledge of the structure-function relationship between the sub-tissue properties and bulk tissue mechanics is important for understanding tissue failure mechanics and developing biological repair strategies. Difficulties in directly measuring sub-tissue properties led to a growing

Quantitative computed tomography (QCT)-based finite element (FE) models of the vertebra are widely used in studying spine biomechanics and mechanobiology, but their accuracy has not been fully established. Although the models typically assign material properties based only on local bone mineral density (BMD), the mechanical behavior of trabecular bone also depends on fabric. The goal of this study

Hemolysis is a major concern in blood-circulating devices, which arises due to non-physiological stresses on red blood cells from ambient flow environment or moving mechanical structures. Computational fluid dynamics (CFD) and empirical hemolysis prediction models have been increasingly used for the design and optimization of blood-circulating devices. The commonly used power-law models for hemolysis