Cellular micromechanics

Keywords QCM Cell-substrate interactions Cell adhesion Cell spreading Extracellular matrix Cellular micromechanics Cytoskeleton Cell elasticity ... 

An array of micromechanical stimulators are microfabricated for high-throughput cytomechanics studies and can exist in the form of two-dimensiraial or three-dimensional cultures. Besides the ability to examine the effects of varying mechanical strains on the cellular activities, this system can incorporate various nonmechanical parameters (e.g., biomaterials and chemical stimulation) to facilitate parallel combinatorial screening with mechanical strain parameters. 

Besides that, compressive force can be manipulated to facilitate cell lysis and collect their cellular components for later cell-based assay. Similarly, Wang et al. fabricated a micromechanical stimulator fliat is capable of providing controlled compressive or tensile strain to the cultured cells in vitro (Fig. 4). Experimental characterization of its PDMS membrane deformation showed that the microdevice can provide —6 % compressive to 25 % tensile radial strain to the cultured cells within the membrane center [6], which allowed simultaneous investigation of both mechanical strains on the same cells. Zhou et al. developed a microchip platform with microchannels that resembles the mechanical environment of small blood vessels in vivo (Fig. 5). They demonstrated that the deformation of the membrane by hydraulic pressure induced cyclic circumferential strains on the adhered mesenchymal stem cells and thus caused significant stmctural and biochemical changes to the cells [7]. 

Cellular Mechanotransduction in Microfluidic Systems, Fig. 3 Schematics of micromechanical device cross section, (a) At rest and (b) hydraulic deflection of PDMS membrane to provide compressive stress on the adhered cells (Reprinted with permission from Kim et al. [5])... 

Cellular Mechanotransduction in Microfluidic Systems, Fig. 5 Overview and operation of the artificial vessel micromechanical chip, (a) Biomechanical stimulation of native arteries, (b) Microfluidic artificial vessels capable of producing quasi-circumferential strain that... 

In these types of polymers the micromechanical behavior depends on the interrelation between cavitation and micronecking. Two examples of deformed SBM diblock copolymers with 76% PS and hexagonal-packed poly(butyl methacrylate) (PBMA) cylinders embedded in the PS matrix are shown in Fig. 3.9. Figure 3.9(a) shows craze-like deformation zones running perpendicular to the main strain direction (shown by an arrow). Inside the crazes, both the PBMA cylinders and PS matrix show large plastic deformation. In Fig. 3.9(b) a craze is seen, created by a cellular structure of cavitated PBMA cylinders and plastic deformation of the PS matrix [21], Several types of deformation structures and crazes can be formed in block copolymers initiated by cavitation of one phase and plastic deformation of both phases. However, due to structures on much smaller length scales, there are a number of unique characteristics of the deformation mechanisms [6]. 

Cells are endowed with the ability to sense their chemical and mechanical environment and to alter their shape, migration, and proliferation in response to environmental cues. These responses lead to the self-organizing behavior that drives morphogenesis, and are affected by changes in the balance of mechanical forces within and around the cell. The discovery of the importance of cell shape, cytoskeletal tension, and motion for control of the cell-cycle progression requires a study of the micromechanics, cellular architecture, and structural complexity of supporting materials. 

Kraynik AM, Neilsen MK, Reinelt DA, Warren WE (1999) Foam Micromechanics Structure and Rheology of Foams, Emulsions and Cellular Solids. In Sadoc F, Rivier N (eds) Foams and Emulsions. NATO ASl Series. Kluwer, Dordrecht, p 259... 

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