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Mechanobiological Evidence for the Control of Neutrophil Activity by Fluid Shear Stress
Published in Jiro Nagatomi, Eno Essien Ebong, Mechanobiology Handbook, 2018
Hainsworth Y. Shin, Xiaoyan Zhang, Ayako Makino, Geert W. Schmid-Schönbein
Pseudopods are local cytoplasmic projections physically supported by polymerized cytoskeletal proteins such as F-actin. These structures are formed following a process whereby the cell surface projects membrane processes called lamellipodia (i.e., membrane ruffles; not to be confused with smaller membrane folds on a passive neutrophil surface) resulting from polymerization of monomeric cytoskeletal proteins (e.g., G-actin to F-actin fibers) into a filamentous network at the leading edge (Zhelev and Alteraifi, 2002). As these structures increase in size, cytoplasmic material flows. Hence, pseudopods projected by activated neutrophils are actin-enriched cellular projections (Figure 12.10) filled with cytoplasmic material and typically of a width that is on the same order of magnitude as the diameter of the neutrophil (Ehrengruber et al., 1996). In comparison, inactivated neutrophils (e.g., after shear stress exposure) do not extend pseudopods and exhibit F-actin localized to the cell cortex (Figure 12.10).
CelIs as physical objects
Published in A. Šiber, P. Ziherl, Cellular Patterns, 2018
The microscopic workings of cell‐cell interaction are rather complex, and so is the interaction of cells with the extracellular matrix. This network of protein fibers such as collagen, elastin, fibronectin, and laminin is a key component of many body structures including connective tissue, and some migratory cells, such as mesenchymal cells discussed in Sections 5.4 and 5.5, move in space by attaching to the matrix. These cells extend protrusions to nearby objects including the extracellular matrix, attach to them, and then actively contract the protrusions so as to move toward the anchor. The large protrusions are known as lamellipodia, thin sheet‐like projections of membrane from the leading edge of the cell (Figure 2.11). A lamellipodium consists mainly of a network of actin filaments capable of generating contractile stresses and its leading edge contains many filopodia, smaller finger‐like protrusions containing bundles of actin filaments bound together by fascin.
Tuning Cellular Behaviors during Self-Organization of Cells in Hydrogel by Changing Inner Nano-Structure of Hydrogel
Published in Xiaolu Zhu, Zheng Wang, Self-Organized 3D Tissue Patterns, 2022
In our observation, filopodia and lamellipodia were the two main cellular growing structures during sprouting and spreading. Lamellipodia are cytoskeletal protein actin projections on the front edge of the cell. Filopodia are slender cytoplasmic projections extending from the front edge of lamellipodia in migration cells. In 3D, most 3T3 and C2C12 cells were usually observed growing out some slender filopodia, while their lamellipodia were relatively inconspicuous in the hydrogel (Figure 6.5a). In 2D, both 3T3 and C2C12 cells had attachment, with their filopodia and lamellipodia adherent on the surface of petri dishes (Figures 6.5a). The polygon-shape of cells in 2D was mainly associated to the amount and morphology of their cellular lamellipodia.
A minimal biomechanical model for random cell migration
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
I. Manifacier, A. Chauvière, C. Verdier, G. Chagnon, I. Cheddadi, N. Glade, A. Stéphanou
The cell movement is achieved by the collective interaction between all of the protrusions. Lamellipodia expand the reach of the cell and then mature into a contractile protrusion that pulls together, from both ends, on the rest of the cell.