Fabrication of a tailor-made conductive polyaniline/ascorbic acid-coated nanofibrous mat as a conductive and antioxidant cell-free cardiac patch.

Polyaniline (PANI) waspolymerized on nanofibrous polycaprolactone mats as cell-free antioxidant cardiac patches (CPs), providing electrical conductivity and antioxidant properties. The fabricated CPs took advantage of intrinsic and additive antioxidant properties in the presence of PANI backbone and ascorbic acid as a biocompatible dopant of PANI. The antioxidant nature of CPs may reduce the serious repercussions of oxidative stress, produced during the ischemia-reperfusion (I/R) process following myocardial infarction.

Nanoscale vibration could promote tenogenic differentiation of umbilical cord mesenchymal stem cells.

Regulation of mesenchymal stem cell (MSC) fate for targeted cell therapy applications has been a subject of interest, particularly for tissues such as tendons that possess a marginal regenerative capacity. Control of MSCs' fate into the tendon-specific lineage has mainly been achieved by implementation of chemical growth factors. Mechanical stimuli or 3-dimensional (D) scaffolds have been used as an additional tool for the differentiation of MSCs into tenocytes, but oftentimes, they require a sophisticated bioreactor or a complex scaffold fabrication technique which reduces the feasibility of the proposed method to be used in practice.

Analysis of EMT induction in a non-invasive breast cancer cell line by mesenchymal stem cell supernatant: Study of 2D and 3D microfluidic based aggregate formation and migration ability, and cytoskeleton remodeling.

Aims: The process of Epithelial-to-mesenchymal transition (EMT) as a phenotypic invasive shift and the factors affecting it, are under extensive research. Application of supernatants of human adipose-derived mesenchymal stem cells (hADMSCs) on non-invasive cancer cells is a well known method of in vitro induction of EMT like process. While previous researches have focused on the effects of hADMSCs supernatant on the biochemical signaling pathways of the cells through expression of different proteins and genes, we investigated pro-carcinogic alterations of physico-mechanical cues in terms of changes in cell motility and aggregated formation in 3D microenvironments, and cytoskeletal actin-myosin content and fiber arrangement.

Effects of chemically EGFR targeting on non-targeted physical cell behaviors in 2D and 3D microfluidic cultures of invasive and non-invasive breast cancer cell lines.

Cancer development comprehends changes in cell structural and physical states. Cancer cells are softer than normal cells, produce higher contractile forces, and migrate more easily. While chemotherapy, targets proteins involved in biological behaviors, it may affect cell physicomechanical state due to the interconnections among signaling pathways.

The functional cross talk between cancer cells and cancer associated fibroblasts from a cancer mechanics perspective.

The function of biological tissues in health and disease is regulated at cellular level and is highly influenced by the physical microenvironment, through the interaction of forces between cells and ECM, which are perceived through mechanosensing pathways. In cancer, both chemical and physical signaling cascades and their interactions are involved during cell-cell and cell-ECM communications to meet requirements of tumor growth. Among stroma cells, cancer associated fibroblasts (CAFs) play key role in tumor growth and pave the way for cancer cells to initiate metastasis and invasion to other tissues, and without recruitment of CAFs, the process of cancer invasion is dysfunctional.

Chemical inhibitor anticancer drugs regulate mechanical properties and cytoskeletal structure of non-invasive and invasive breast cancer cell lines: Study of effects of Letrozole, Exemestane, and Everolimus.

Regardless of their target and mechanism, anticancer drugs directly influence biological behavior of cancer cells by activating chemical signaling pathways. Due to the complex interaction between diverse signaling pathways, these drugs may profoundly impact the physical characteristics of cancer cells and regulate their mechanical properties. In this study, the effects of two Aromatase Inhibitor (Letrozole and Exemestane), and one mTOR Inhibitor (Everolimus) on cell mechanical properties, actin content/distribution, and nuclear areas of two invasive and non-invasive breast cancer cell line after 24 h treatment with concentrations previously reported were investigated.

Contribution of atherosclerotic plaque location and severity to the near-wall hemodynamics of the carotid bifurcation: an experimental study and FSI modeling.

Atherosclerosis is initiated by endothelial injury that is related to abnormal values of hemodynamic parameters such as wall shear stress (WSS), oscillatory shear index (OSI) and stress phase angle (SPA), which are more common in arterial bifurcations due to the complex structure. An experimental model of human carotid bifurcation with accurate geometrical and mechanical features was set up, and using realistic pulsatile flow rates, the inlet and outlet pressure pulses were measured for normal and stenosed models with 40% and 80% severities at common carotid (CCA), internal carotid (ICA) and external carotid (ECA) arteries. Based on the obtained experimental data, fluid-structure models were developed to obtain WSS, OSI, and SPA and evaluate pathological consequences at different locations.

Altered mechanical properties of actin fibers due to breast cancer invasion: parameter identification based on micropipette aspiration and multiscale tensegrity modeling.

The biophysical properties of cells change with cancer invasion to fulfill their metastatic behavior. Cell softening induced by cancer is highly associated with alterations in cytoskeleton fibers. Changes in the mechanical properties of cytoskeletal fibers have not been quantified due to technical limitations.

Nonlinear viscoelastic properties of human dentin under uniaxial tension.

Objective: Dentin is a viscoelastic tissue that contributes to the load distribution in human teeth and leads to their fracture resistance. Despite previous researches on the time-dependent behavior of dentin, it is not very clear whether the viscoelastic behavior of this tissue is linear or nonlinear, and what viscoelastic constitutive equations mechanically characterize it. Therefore, the aim of this study was to describe the viscoelastic behavior of human dentin and determine the best-fitting viscoelastic model for this tissue.

Characterizing the effect of substrate stiffness on the extravasation potential of breast cancer cells using a 3D microfluidic model.

Different biochemical and biomechanical cues from tumor microenvironment affect the extravasation of cancer cells to distant organs; among them, the mechanical signals are poorly understood. Although the effect of substrate stiffness on the primary migration of cancer cells has been previously probed, its role in regulating the extravasation ability of cancer cells is still vague. Herein, we used a microfluidic device to mimic the extravasation of tumor cells in a 3D microenvironment containing cancer cells, endothelial cells, and the biological matrix.

The microenvironment and cytoskeletal remodeling in tumor cell invasion.

The physical cues of tumor microenvironment (TME) contribute greatly to the initiation and progression of cancer. Tumor tissues usually become stiffer than healthy tissues with more aligned fibers and changed porosity. In recent years, numerous studies attempted to investigate whether biophysical cues from the surrounding environment affect the biophysical, biochemical, and biological behavior of cells and consequently attribute to the development of cancer.

Mechanics of actin filaments in cancer onset and progress.

Cancer, as a major cause of mortality, is highly related to alterations in the structure and behavior of cells of cancerous tissues. The invasive nature of cancer cells is correlated with their increased traction force, high deformability and altered cell adhesion. These changes are directly attributed to the remodeling of cell cytoskeleton mostly in actin structure.

An AFM-Based Nanomechanical Study of Ovarian Tissues with Pathological Conditions.

Background: Different diseases affect both mechanical and chemical features of the involved tissue, enhancing the symptoms.

Methods: In this study, using atomic force microscopy, we mechanically characterized human ovarian tissues with four distinct pathological conditions: mucinous, serous, and mature teratoma tumors, and non-tumorous endometriosis. Mechanical elasticity profiles were quantified and the resultant data were categorized using K-means clustering method, as well as fuzzy C-means, to evaluate elastic moduli of cellular and non-cellular parts of diseased tissues and compare them among four disease conditions.

Effects of substrate mechanics on angiogenic capacity and nitric oxide release in human endothelial cells.

Loss of vascular elasticity results from progressive degeneration of the extracellular matrix of elastic arteries under the effect of aging and certain diseases, including atherosclerosis. To investigate the influence of vessel wall stiffening on endothelial cell (EC) function, we seeded human umbilical vein ECs onto variably compliant polydimethylsiloxane substrates. When plated on the more compliant substrate, ECs assembled into capillary-like structures.

Correlation of the cell mechanical behavior and quantified cytoskeletal parameters in normal and cancerous breast cell lines.

Background: Cancerous transformation of cells affects their mechanical behavior and cytoskeleton structure.

Objective: The objective of this research is to investigate a correlation between mechanical properties and cytoskeletal structure features in cancer cell formation.

Methods: Micropipette aspiration was used to compare mechanical properties of normal (MCF10A) and cancerous (T47D) epithelial breast cell lines.

Modulating cancer cell mechanics and actin cytoskeleton structure by chemical and mechanical stimulations.

To date, a myriad of strategies has been suggested for targeting the chemical signaling of cancer cells. Also, biomechanical features are gaining much more attention. These features can be used as biomarkers which influence cancer progression.

Progressive changes of elastic moduli of arterial wall and atherosclerotic plaque components during plaque development in human coronary arteries.

Stiffness of the arterial wall and atherosclerotic plaque components is a determinant of the stress field within plaques, which has been suggested to be an indicator of plaque vulnerability. The diversity and inhomogeneous structure of atherosclerotic lesions complicate the characterization of plaque components. In the present study, stiffness of the arterial wall and atherosclerotic plaque components in human coronary arteries was examined in early and developed atherosclerotic lesions.

Effect of equiaxial cyclic strain on cardiomyogenic induction in mesenchymal stem cells.

Differentiation of stem cells and functionality of target cells are regulated by microenvironmental stimuli to which the cells are exposed. Chemical agents such as growth factors and physical parameters including mechanical loadings are among major stimuli. In this study, equiaxial cyclic strain with two amplitudes was applied on rat adipose-derived mesenchymal stem cells (rAMSCs) with or without 5-azacytidine.

Substrate topography interacts with substrate stiffness and culture time to regulate mechanical properties and smooth muscle differentiation of mesenchymal stem cells.

Substrate stiffness and topography are two powerful means by which mesenchymal stem cells (MSCs) activities can be modulated. The effects of substrate stiffness on the MSCs mechanical properties were investigated previously, however, the role of substrate topography in this regard is not yet well understood. Moreover, in vessel wall, these two physical cues act simultaneously to regulate cellular function, hence it is important to investigate their cooperative effects on cellular activity.

Cytoskeletal remodeling induced by substrate rigidity regulates rheological behaviors in endothelial cells.

Altered microenvrionmental mechanical cues induce cytoskeletal remodeling in cells and have a profound impact on their functions as well as rheological properties. This article is aimed to characterize the viscoelastic behavior of endothelial cells, cultivated on variably compliant substrates. Synthetic tunable poly(dimethylsyloxane) substrates, with elastic moduli ranging from 1.

The effects of short-term uniaxial strain on the mechanical properties of mesenchymal stem cells upon TGF-β stimulation.

Cellular mechanical characteristics represent cell ability to produce tissue-specific metabolites. Therefore, to achieve effective cell therapy, a better understanding of the effects of chemo-mechanical stimuli on the mechanical properties of in vitro-treated cells is essential. Herein, we investigated the effects of uniaxial strain on the mechanical properties of mesenchymal stem cells (MSCs) upon transforming growth factor beta 1 (TGF-β) stimulation.

Mechanical Characterization of the Lamellar Structure of Human Abdominal Aorta in the Development of Atherosclerosis: An Atomic Force Microscopy Study.

Atherosclerosis is a major risk factor for cardiovascular disease. However, mechanisms of interaction of atherosclerotic plaque development and local stiffness of the lamellar structure of the arterial wall are not well established. In the current study, the local Young's modulus of the wall and plaque components were determined for three different groups of healthy, mildly diseased and advanced atherosclerotic human abdominal aortas.

Behavioral remodeling of normal and cancerous epithelial cell lines with differing invasion potential induced by substrate elastic modulus.

The micro-environment of cancer cells in the body is mechanically stiffer than that of normal cells. We cultured three breast cell lines of MCF10A-normal, MCF7-noninvasive, and MDA-MB-231-invasive on PDMS substrates with different elastic moduli and different cellular features were examined.Effects of substrate stiffness on cell behavior were evident among all cell lines.

Radiation therapy affects the mechanical behavior of human umbilical vein endothelial cells.

Radiation therapy has been widely utilized as an effective method to eliminate malignant tumors and cancerous cells. However, subjection of healthy tissues and the related networks of blood vessels adjacent to the tumor area to irradiation is inevitable. The aim of this study was to investigate the consequent effects of fractionation radiotherapy on the mechanical characteristics of human umbilical vein endothelial cells (HUVECs) through alterations in cytoskeleton organization and cell and nucleus morphology.

Stress phase angle regulates differentiation of human adipose-derived stem cells toward endothelial phenotype.

Endothelial cells are subjected to cyclic shear by pulsatile blood flow and pressures due to circumferential stresses. Although most of the researches on this topic have considered the effects of these two biomechanical forces separately or concurrently, few studies have noticed the interaction of these cyclic loadings on endothelial behavior. Negative temporal stress phase angle, defined by the phase lag between cyclic shear and tensile stresses, is an established parameter which is known to have substantial effects on blood vessel remodeling and progression of some serious cardiovascular diseases.