Skeletal muscle cells are sensitive to sustained compression, which can lead to the development of pressure sores. Although it is known that this type of tissue breakdown depends on the magnitude and duration of the applied load, the exact relationship between cell deformation and damage remains unclear. To gain more insight into this process, a method has been developed, that incorporates the use of a new loading device and confocal microscopy. The loading device is able to compress individual cells, either statically or dynamically, while measuring the resulting forces. Experiments can be performed under ideal environmental conditions, comparable with those of a CO2 incubator. First compression experiments on C2C12 mouse myoblasts showed the shape changes that cells undergo during static compression by the loading device. Calculations using the three-dimensional confocal images showed no change in volume and an increase in the surface area of the cell as a result of compression. The device presented here provides a useful way to monitor the biomechanical response of skeletal muscle cells during long-term compression experiments. Therefore it will contribute to the knowledge about strain-induced cell damage, as seen in pressure sores and other mechanically induced clinical conditions.
"However, various cell types behave as the elastic bodies. Young's modulus for animal cells is in the range of E c ¼ 0:1 À 100 kPa (Peeters et al., 2003). Young's modulus for living cells is lower than for dead cells. "
[Show abstract][Hide abstract] ABSTRACT: Abstract Various modeling approaches have been applied to describe the rearrangement of immobilized cell clusters within the extracellular matrix. The cell rearrangement has been related with the micro-environmental restrictions to cell growth. Herein, an attempt is made to discuss and connect various modeling approaches on various time scales which have been proposed in the literature in order to shed further light to this complex phenomenon which induces micro-environmental restrictions to cell growth. The rearrangement is driven by internal stress generated within the cluster. The internal stress represents a consequence of the matrix rheological response to cell expansion. The rearrangement includes the interplay between the processes of: (1) single and collective cell migrations, (2) cell deformation and orientation, (3) decrease of cell-to-cell separation distances and (4) cell growth. It has been considered on two time scales: a short time scale (i.e. the rearrangement time) and a long time scale (i.e. the growing time). The results indicate that short and long times cell rearrangement induces energy dissipation. The dissipation provokes biological responses of cells which cause the resistance effects to cell growth. Deeper insight in the anomalous nature of the energy dissipation would be useful for understanding the biological mechanisms which causes the resistance effects to cell growth.
"D. Cell Compression 1. Microindentor or microplate made from regular borosilicate bars using a micropipette puller (Sutter Instrument Company, Broers et al., 2004; Peeters et al., 2003). 2. A probe attached to micromanipulators, piezoelectric system, and force transducer (Broers et al., 2004; Peeters et al., 2003). "
[Show abstract][Hide abstract] ABSTRACT: In eukaryotic cells, the nucleus is the largest and most rigid organelle. Therefore, its physical properties contribute critically to the biomechanical behavior of cells, e.g., during amoeboid migration or perfusion through narrow capillaries. Furthermore, it has been speculated that nuclear deformations could directly allow cells to sense mechanical stress, e.g., by modulating the access of specific transcription factors to their binding sites. Defects in nuclear mechanics have also been reported in a variety of muscular dystrophies caused by mutations in nuclear envelope proteins, indicating an important role in the maintenance of cells in mechanically stressed tissue. These findings have prompted the growing field of nuclear mechanics to develop advanced experimental methods to study the physical properties of the nucleus as a function of nuclear structure and organization, and to understand its role in physiology and disease. These experimental techniques include micropipette aspiration, atomic force microscopy of isolated nuclei, cellular strain and compression experiments, and microneedle manipulation of intact cells. These experiments have provided important insights into the mechanical behavior of the nucleus under physiological conditions, the distinct mechanical contributions of the nuclear lamina and interior, and how mutations in nuclear envelope proteins associated with a variety of human diseases can cause distinct alterations in the physical properties of the nucleus and contribute to the disease mechanism. Here, we provide a brief overview of the most common experimental techniques and their application and discuss the implication of their results on our current understanding of nuclear mechanics.
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