Cell Deformation Mechanisms Studied

Miyata, Hidetake, see Akashi, Kenichirou, 6, 45 see also Cell deformation Mechanisms Studied with Actin-containing Giant Vesicles, a Cell-mimicking System.,... 

Cell Deformation Mechanisms Studied with Actin-containing Giant Vesicles, a Cell-mimicking System... 

A collection of polyolefin foams with closed cell structure and different chemical compositions and densities was studied by using SEM, DSC and dynamic mechanical analysis. Deformation mechanisms were also studied. 26 refs. 

The mechanical properties of fibrin are essential for its functions in hemostasis and wound healing, since the clot must stop bleeding and yet allow the penetration of cells. The mechanical properties of a thrombus will determine how it responds to flowing blood, including elastic or plastic deformation and embolization. Epidemiological studies have revealed a relationship between myocardial infarction and clot stiffness (Fatah et al., 1996 Scrutton et al., 1994). 

Mammalian cells and tissues reside in mechanically dynamic microenvironments in the body. Abnormal or excessive physical loads on tissues result in tissue deformation. Numerous studies have confirmed that proper mechanical stimuli applied to cells or tissues contribute to maintaining cell/tissue morphology and inducing specialized functions. Mechanical stimuli have recently been applied to regenerate functional tissues, in particular tissues for the cardiovascular system. To reconstruct functionally active SM tissues that are comparable to native tissues, the re-creation in vitro of in vivo mechano-active microenvironments may be a necessary part of the tissueengineering process. 

Membrane thickness can generally be neglected when it is compared to any cell size. To study the role of the membrane mechanical properties in cell deformability, bilayers or membranes are described as mathematical surfaces, that are homogeneous and of vanishing thickness, whose small shape changes are simply understood using three different elementary deformations characterized by their elastic moduli (Figure 13.1). 

In the study of Smith et al. [1999], a high temporal and spatial resolution microscopy is used to reveal features that previous studies could not capture [Alon et al, 1995]. They found that the measured dissociation constants for neutrophil tethering events at 250 pN/bond are lower than the values predicted by the Bell and Hookean spring models. The plateau observed in the graph of the shear stress vs. the reaction rate kr suggests that there is a force value above which the Bell and spring models are not valid. Since the model proposed so far considers the cell as a rigid body, whether the plateau is due to molecular, mechanical or cell deformation is not clear at this time. 

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