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Cell Biology for Bioprocessing
Published in Wei-Shou Hu, Cell Culture Bioprocess Engineering, 2020
Many cell types, such as fibroblasts, extend their body and spread flat on a surface, both in tissues and in culture. The edge of an adherent cell has an irregular shape, much like an egg laid on a pan. In the protruding regions, actin fibers localize in the lamellipodia and filopodia. In the protruding filopodia, actin filaments form intensely labeled parallel bundles of fibers. While in the lamellipodia, they form cross-linked non-parallel networks. The two types of network can reorganize, the filopodium region protruding out from a lamellipodium during cell movement. In stationary cells, the actin fibers form long stress fibers that may span a large fraction of the entire cell length. The stress fibers connect to the focal adhesion (the location where the cytoplasmic membrane is in contact with the substrate surface) and establish a tension force between the cell and the extracellular matrix. Stress fibers also connect to adjacent cells through adhesion junctions.
Endogenous Bioelectric Phenomena and Interfaces for Exogenous Effects
Published in Ben Greenebaum, Frank Barnes, Bioengineering and Biophysical Aspects of Electromagnetic Fields, 2018
Nerve cells find normally their way with a special elongated process and a groping hand-like triangle, the growth cone. Regarding the instructive—and many other cues overriding—role of EF, Ranjnicek et al. (104) demonstrated the involvement of dynamic microfilaments and MT in EF-directed migration and orientation. The above-mentioned authors studied the dynamics of the growth cone in cultured Xenopus embryonic spinal neurons. With the use of specific inhibitors they could reveal an orchestrated interplay of microfilaments and MT. Dynamically, the filopodia of the growth cone turned to the cathode, suggesting an instructive role in EF-induced steering. Lamellipodial asymmetry accompanied this turning. The filopodia and lamellipodia are regulated by the GTPases Cdc42 and Rac, respectively, and peptides that selectively prevented effector binding to Cdc42 or Rac abolished cathodal growth cone turning.
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.
Multi-responsive on-demand drug delivery PMMA-co-PDEAEMA platform based on CO2, electric potential, and pH switchable nanofibrous membranes
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Mohsen Gorji, Dara Zarbaf, Saeedeh Mazinani, Abolfazl Sajadi Noushabadi, Monica A. Cella, Ali Sadeghianmaryan, Ali Ahmadi
Electrospun drug-loaded nanofibrous membranes are highly favourable in tissue engineering applications due to their ability to provide necessary nutrients and metabolic exchange capabilities, which are crucial for cell adhesion and proliferation [81–84]. To evaluate the cell adhesion and growth on the CUR-loaded electrospun membrane, fibroblast cells were seeded on the samples for 1, 3, and 7 days. FE-SEM images at different magnifications were taken from the 1-day cell-seeded sample (Figure 8). According to the results, the fibroblast cells were completely attached to the surface of the membrane, exhibiting filopodia formation. The cell viability of the three samples was evaluated using the MTT assay (Figure 9). The 3-day seeded (Figure 9b) and 7-day seeded (Figure 10c) samples demonstrate minimal change to the cell shape compared to the control (Figure 9a), whereas the 1-day seeded sample was omitted from the results due to being highly similar to the control sample. The samples demonstrated high biocompatibility with approximately 95%, 87%, and 83% cell viability after 1, 3, and 7 days of cell culture, respectively (Figure 9). According to a previous study, average relative cell viability of over 60% indicates low toxicity to human dermal fibroblasts [85].
PEGylated TiO2 nanoparticles mediated inhibition of cell migration via integrin beta 1
Published in Science and Technology of Advanced Materials, 2018
Qingqing Sun, Koki Kanehira, Akiyoshi Taniguchi
pFAK is important for cell migration, as it could integrate growth factor and integrin signals to promote cell migration [51], and expression of the protein-tyrosine phosphatase (PTEN) induces dephosphorylation of FAK and inhibition of cell migration [52]. Besides that, cell spreading and migration were enhanced after overexpression of FAK, compared with those of FAK-null cells [53,54]. While FAK deficient cells display a rounded morphology, increased formation of cell-substratum contact sites and migration defects [54]. pFAK, as the transduction signaling of cell migration, is activated by integrins. So, less expression of integrin beta 1 reduced the activation of pFAK, leading to weaker signaling of cell migration. Besides that, pFAK could maintain the stability of protrusions (lamellipodia and filopodia) of f-actin to modulate cell migration [43,44,55]. Therefore, when the expression of pFAK was decreased, the integrity of bundled actin filaments was also damaged, which deceased the polarity of cellular skeleton and thereby cell migration.
The response of bone cells to titanium surfaces modified by simvastatin-loaded multilayered films
Published in Journal of Biomaterials Science, Polymer Edition, 2018
Min Lai, Xufeng Yan, Ziyang Jin
The first event to occur when a biomaterial is placed in a cellular environment is cellular adhesion. This subsequently affects other functions such as cell proliferation and differentiation. Figure 5A displays the morphology of MSCs grown onto different titanium substrates. There are many dense filopodia stretching out to anchor to the surface on LBL coated Ti and SV-LBL coated Ti substrates (Figure 5A c & d, white arrows), which is regulated by the remodeling of actin cytoskeleton and peripheral focal adhesion [35]. The results showed multilayered nano-Ti and SV multilayered nano-Ti substrates promoted cell adhesion, even simvastatin was inserted into the layers. Just because chitosan/gelatin layers displayed good biocompatibility [34].