Microstring-engineered tension tissues: a novel platform for replicating tissue mechanics and advancing mechanobiology.

Replicating the mechanical tension of natural tissues is essential for maintaining organ function and stability, posing a central challenge in tissue engineering and regenerative medicine. Existing methods for constructing tension tissues often encounter limitations in flexibility, scalability, or cost-effectiveness. This study introduces a novel approach to fabricating soft microstring chips using a sacrificial template method, which is easy to operate, offers controlled preparation, and is cost-effective.

A Microactuator Array Based on Ionic Electroactive Artificial Muscles for Cell Mechanical Stimulation.

Mechanical stimulation is prevalent within organisms, and appropriate regulation of such stimulation can significantly enhance cellular functions. Consequently, the in vitro construction and simulation of mechanical stimulation have emerged as a research hotspot in biomechanics. In recent years, a class of artificial muscles named electroactive polymers (EAPs), especially ionic EAPs, have shown promising applications in biomechanics.

Engineering Soft Spring Gauges for In Situ Biomaterial and Tissue Weighing.

Hydrogels have gained great attention and broad applications in tissue engineering, regenerative medicine, and drug delivery due to their excellent biocompatibility and degradability. However, accurately and noninvasively characterizing the degradation process of hydrogels remains a challenge. To address this, we have developed a method using soft spring gauges (SSGs) for the in situ weighing of hydrogels.

Mechanotherapy in oncology: Targeting nuclear mechanics and mechanotransduction.

Mechanotherapy is proposed as a new option for cancer treatment. Increasing evidence suggests that characteristic differences are present in the nuclear mechanics and mechanotransduction of cancer cells compared with those of normal cells. Recent advances in understanding nuclear mechanics and mechanotransduction provide not only further insights into the process of malignant transformation but also useful references for developing new therapeutic approaches.

An ECM-Mimicking, Injectable, Viscoelastic Hydrogel for Treatment of Brain Lesions.

Brain lesions can arise from traumatic brain injury, infection, and craniotomy. Although injectable hydrogels show promise for promoting healing of lesions and health of surrounding tissue, enabling cellular ingrowth and restoring neural tissue continue to be challenging. It is hypothesized that these challenges arise in part from the mismatch of composition, stiffness, and viscoelasticity between the hydrogel and the brain parenchyma, and this hypothesis is tested by developing and evaluating a self-healing hydrogel that not only mimics the composition, but also the stiffness and viscoelasticity of native brain parenchyma.

Dynamic and static biomechanical traits of cardiac fibrosis.

Cardiac fibrosis is a common pathology in cardiovascular diseases which are reported as the leading cause of death globally. In recent decades, accumulating evidence has shown that the biomechanical traits of fibrosis play important roles in cardiac fibrosis initiation, progression and treatment. In this review, we summarize the four main distinct biomechanical traits (i.

A positive mechanobiological feedback loop controls bistable switching of cardiac fibroblast phenotype.

Cardiac fibrosis is associated with activation of cardiac fibroblasts (CFs), a pathological, phenotypic transition that is widely believed to be irreversible in the late stages of disease development. Sensing of a stiffened mechanical environment through regulation of integrin-based adhesion plaques and activation of the Piezo1 mechanosensitive ion channel is known to factor into this transition. Here, using integrated in vitro and in silico models, we discovered a mutually reinforcing, mechanical positive feedback loop between integrin β1 and Piezo1 activation that forms a bistable switch.

Differential Responses of Primary Astrocytes Under Hyperthermic Temperatures.

Astrocyte is the most abundant cells in brain and plays critical roles in brain homeostasis and functions. Although hyperthermia (or fever) is a common symptom in patients, its influence on astrocyte viability, morphology, and functions remains elusive. Here we developed an in vitro astrocyte culture system capable of precisely controlling culture temperature to study astrocyte responses under clinically-relevant hyperthermic temperatures (38 ∼ 41 °C).

Plasmonic Ag Nanoparticle-Loaded n-p BiOCO/α-BiO Heterojunction Microtubes with Enhanced Visible-Light-Driven Photocatalytic Activity.

In this study, n-p Bi2O2CO3/α-Bi2O3 heterojunction microtubes were prepared via a one-step solvothermal route in an H2O-ethylenediamine mixed solvent for the first time. Then, Ag nanoparticles were loaded onto the microtubes using a photo-deposition process. It was found that a Bi2O2CO3/α-Bi2O3 heterostructure was formed as a result of the in situ carbonatization of α-Bi2O3microtubes on the surface.

Effect of gene mutation of plants on their mechano-sensibility: the mutant of EXO70H4 influences the buckling of Arabidopsis trichomes.

With the development of molecular biology, more and more mutants of plants have been constructed, where gene mutants have been found to influence not only the biological processes but also biophysical behaviors of plant cells. Trichomes are an important appendage, which has been found to act as an active mechanosensory switch transducing mechanical signals into physiology changes, where the mechanical property of trichomes is vital for such functions. Up to now, over 40 different genes have been found with the function of regulating trichome cell morphogenesis; however, the effect of gene mutants on trichome mechanosensory function remains elusive.

A new model of myofibroblast-cardiomyocyte interactions and their differences across species.

Although coupling between cardiomyocytes and myofibroblasts is well known to affect the physiology and pathophysiology of cardiac tissues across species, relating these observations to humans is challenging because the effect of this coupling varies across species and because the sources of these effects are not known. To identify the sources of cross-species variation, we built upon previous mathematical models of myofibroblast electrophysiology and developed a mechanoelectrical model of cardiomyocyte-myofibroblast interactions as mediated by electrotonic coupling and transforming growth factor-β1. The model, as verified by experimental data from the literature, predicted that both electrotonic coupling and transforming growth factor-β1 interaction between myocytes and myofibroblast prolonged action potential in rat myocytes but shortened action potential in human myocytes.

Bioinspired Microstructure Platform for Modular Cell-Laden Microgel Fabrication.

Cell-laden microgels have attracted increasing interest in various biomedical fields, as living building blocks to construct spatially organized multicellular structures or complex tissue features (e.g., cell spheroids and aligned cells/fibers).

Investigating the Effect of Substrate Stiffness on the Redox State of Cardiac Fibroblasts Using Scanning Electrochemical Microscopy.

Cardiac fibrosis, in which cardiac fibroblasts differentiate into myofibroblasts, leads to oversecretion of the extracellular matrix, results in increased stiffness, and facilitates disequilibrium of cellular redox state, further leading to oxidative stress and various degrees of cell death. However, the relationship between the matrix stiffness and the redox status of cardiac fibroblasts remains unclear. In this work, we constructed an cardiac fibrosis model by culturing cardiac fibroblasts on polyacrylamide gels with tunable stiffness and characterized the differentiation of cardiac fibroblasts to myofibroblasts by immunofluorescence staining of α-smooth muscle actin.

The Plasticity of Nanofibrous Matrix Regulates Fibroblast Activation in Fibrosis.

Natural extracellular matrix (ECM) mostly has a fibrous structure that supports and mechanically interacts with local residing cells to guide their behaviors. The effect of ECM elasticity on cell behaviors has been extensively investigated, while less attention has been paid to the effect of matrix fiber-network plasticity at microscale, although plastic remodeling of fibrous matrix is a common phenomenon in fibrosis. Here, a significant decrease is found in plasticity of native fibrotic tissues, which is associated with an increase in matrix crosslinking.

Solvent-Free Fabrication of Carbon Nanotube/Silk Fibroin Electrospun Matrices for Enhancing Cardiomyocyte Functionalities.

Cardiac tissue engineering holds great potential in regenerating functional cardiac tissues for various applications. The major strategy is to design scaffolds recapitulating the native cardiac microenvironment to enhance cell and tissue functionalities. Among various biomaterial systems, nanofibrous matrices with aligned morphologies and enhanced conductivity incline to induce the formation of oriented engineered cardiac tissues with enhanced functionalities.

Engineering Biomaterials and Approaches for Mechanical Stretching of Cells in Three Dimensions.

Mechanical stretch is widely experienced by cells of different tissues in the human body and plays critical roles in regulating their behaviors. Numerous studies have been devoted to investigating the responses of cells to mechanical stretch, providing us with fruitful findings. However, these findings have been mostly observed from two-dimensional studies and increasing evidence suggests that cells in three dimensions may behave more closely to their behaviors.

Fluorescent conjugated polymer nanovector for in vivo tracking and regulating the fate of stem cells for restoring infarcted myocardium.

Stem cell therapy holds great promise for cardiac regeneration. However, the lack of ability to control stem cell fate after in vivo transplantation greatly restricts its therapeutic outcomes. MicroRNA delivery has emerged as a powerful tool to control stem cell fate for enhanced cardiac regeneration.

Matrix stiffness controls cardiac fibroblast activation through regulating YAP via AT R.

Cardiac fibrosis is a common pathway leading to heart failure and involves continued activation of cardiac fibroblasts (CFs) into myofibroblasts during myocardium damage, causing excessive deposition of the extracellular matrix (ECM) and thus increases matrix stiffness. Increasing evidence has shown that stiffened matrix plays an important role in promoting CF activation and cardiac fibrosis, and several signaling factors mediating CF mechanotransduction have been identified. However, the key molecules that perceive matrix stiffness to regulate CF activation remain to be further explored.

Nanoscale integrin cluster dynamics controls cellular mechanosensing via FAKY397 phosphorylation.

Transduction of extracellular matrix mechanics affects cell migration, proliferation, and differentiation. While this mechanotransduction is known to depend on the regulation of focal adhesion kinase phosphorylation on Y397 (FAKpY397), the mechanism remains elusive. To address this, we developed a mathematical model to test the hypothesis that FAKpY397-based mechanosensing arises from the dynamics of nanoscale integrin clustering, stiffness-dependent disassembly of integrin clusters, and FAKY397 phosphorylation within integrin clusters.

Differential Effects of Directional Cyclic Stretching on the Functionalities of Engineered Cardiac Tissues.

Cardiac tissue engineering aims to regenerate functional cardiac tissues through recapitulating the native microenvironmental cues, where cardiomyocytes are highly oriented and rhythmically contract along their long-axis direction in the native myocardium. In addition, the different oriented layers of the left ventricle lead to a dynamic biaxial stretching on cardiomyocytes, which makes the mechanical microenvironment in the myocardium much more complex. Thus, it is important to investigate the effect of dynamic mechanical stimulation along different directions to preoriented cardiomyocytes on the functionalities of engineered cardiac tissues.

Microchannel Stiffness and Confinement Jointly Induce the Mesenchymal-Amoeboid Transition of Cancer Cell Migration.

The physical confinement of cell microenvironment could enhance the invasive capability and drug resistance of cancer cells. However, due to the lack of in vitro experimental platform to mimic both stiffness and confinement of the tumor microenvironment, the underlying mechanism remains elusive. Here, we developed a hydrogel-based microchannel platform with independently tunable channel stiffness and width in a physiological range.

Improved Resolution and Fidelity of Droplet-Based Bioprinting by Upward Ejection.

Bioprinting has emerged as a powerful biofabrication technology with widespread applications in biomedical fields because of its superiority in high-throughput, high-precision, 3D structure fabrication. For bioprinting, two of the most important parameters are the printing precision (i.e.

A mechanoelectrical coupling model of neurons under stretching.

Neurons are situated in a microenvironment composed of various mechanical cues, where stretching is thought to have a major impact on neurons, resulting in microstructural changes in neural tissue and further leading to abnormal electrophysiological function. In spite of significant experimental efforts, the underlying mechanism remains elusive, more works are needed to provide a detailed description of the process that leads to the observed phenomena. Here, we developed a mechanoelectrical coupling model of central neurons under stretching and specially considered the plastic deformation of neurons.