Collective cell traction force analysis on aligned smooth muscle cell sheet between three-dimensional microwalls

The modulation of lung cancer cell motility by Calponin 3 is achieved through its ability to sense and respond to changes in substrate stiffness

The influence of extracellular matrix (ECM) stiffness on cell behavior is a well-established phenomenon. Tumor development is associated with the stiffening of the ECM. However, the understanding of the role of biomechanical behavior and mechanotransduction pathways in the oncogenesis of tumor cells remains limited. In this study, we constructed in vitro models using Polydimethylsiloxane substrates to create soft and stiff substrates. We then evaluated the migration of lung cancer cells A549 using video-microscopy and transwell assays. The mechanical properties were assessed through the utilization of atomic force microscopy, Optical Magnetic Twisting Cytometry, and traction force analysis. Additionally, the expression of Calponin 3 (CNN3) was evaluated using reverse transcription‑quantitative PCR and immunofluorescence techniques. Our observations indicate that the presence of a stiff substrate enhances A549 motility, as evidenced by increased stiffness and traction force in A549 cells on the stiff substrate. Furthermore, we observed a decrease in CNN3 expression in A549 cells on the stiff substrate. Notably, when CNN3 was overexpressed, it effectively inhibited the migration and invasion of A549 cells on the stiff substrate. The results of our study provide novel perspectives on the mechanisms underlying cancer cell migration in response to substrate mechanical properties.

Subcellular Force Quantification of Endothelial Cells Using Silicone Pillar Arrays

Micropillar arrays are one of the tools that quantify the mechanical forces exerted by endothelial cells and any other adherent cell types. This chapter describes the fabrication and usage of the micropillars that reports spatial distribution of traction forces by endothelial cells. The fabrication begins with making a "master" pillar substrate using photolithography, followed by softlithography of the master with polydimethylsiloxane. The pillars can then be printed with an extracellular matrix protein in specific shape using stamp-off technique. Lastly, imaging of the micropillars with cells and the analysis of the traction force using Matlab-based software are described.

Soft Polymer-Based Technique for Cellular Force Sensing

Soft polymers have emerged as a vital type of material adopted in biomedical engineering to perform various biomechanical characterisations such as sensing cellular forces. Distinct advantages of these materials used in cellular force sensing include maintaining normal functions of cells, resembling in vivo mechanical characteristics, and adapting to the customised functionality demanded in individual applications. A wide range of techniques has been developed with various designs and fabrication processes for the desired soft polymeric structures, as well as measurement methodologies in sensing cellular forces. This review highlights the merits and demerits of these soft polymer-based techniques for measuring cellular contraction force with emphasis on their quantitativeness and cell-friendliness. Moreover, how the viscoelastic properties of soft polymers influence the force measurement is addressed. More importantly, the future trends and advancements of soft polymer-based techniques, such as new designs and fabrication processes for cellular force sensing, are also addressed in this review.

Progress in Integrative Biomaterial Systems to Approach Three-Dimensional Cell Mechanotransduction

Mechanotransduction between cells and the extracellular matrix regulates major cellular functions in physiological and pathological situations. The effect of mechanical cues on biochemical signaling triggered by cell-matrix and cell-cell interactions on model biomimetic surfaces has been extensively investigated by a combination of fabrication, biophysical, and biological methods. To simulate the in vivo physiological microenvironment in vitro, three dimensional (3D) microstructures with tailored bio-functionality have been fabricated on substrates of various materials. However, less attention has been paid to the design of 3D biomaterial systems with geometric variances, such as the possession of precise micro-features and/or bio-sensing elements for probing the mechanical responses of cells to the external microenvironment. Such precisely engineered 3D model experimental platforms pave the way for studying the mechanotransduction of multicellular aggregates under controlled geometric and mechanical parameters. Concurrently with the progress in 3D biomaterial fabrication, cell traction force microscopy (CTFM) developed in the field of cell biophysics has emerged as a highly sensitive technique for probing the mechanical stresses exerted by cells onto the opposing deformable surface. In the current work, we first review the recent advances in the fabrication of 3D micropatterned biomaterials which enable the seamless integration with experimental cell mechanics in a controlled 3D microenvironment. Then, we discuss the role of collective cell-cell interactions in the mechanotransduction of engineered tissue equivalents determined by such integrative biomaterial systems under simulated physiological conditions.

The role of bifurcation angles on collective smooth muscle cell biomechanics and the implication in atherosclerosis development

A vascular bifurcation angle affects mechanotransduction of a smooth muscle cell sheet and reveals geometrical cues related to early localization of atherosclerosis.