Interactions with the ECM induce a wide variety of cellular responses, whose nature, extent and duration are regulated by multiple features of the surface. These include the specificity of the adhesive ligand, its local density as well as surface topography and stiffness. In collaboration with the group of J. Spatz, from U. Heidelberg, nano-patterned surfaces presenting RGD ligands at variable spacings (ranging from 20-200 nm) are tested for their effect on focal adhesion formation, cell spreading and migration, Mechanisms of cell adhesion and migration Benjamin Geiger Irina Lavelin Yael Paran Ilana Sabanay Victoria Simchaev Tova Volberg Masha Khoutorsky Jens Ulmer Sabina Winograd-Katz Miriam Cohen Elad Landoy Chen Luxenburg Liat Nadav Suha Naffar Abu-Amara Ronen Zaidel-Bar Anat Florentin www.weizmann.ac.il/mcb/Geiger as well as other adhesion-dependent processes.
An example of a nano-patterned surface with a spacing of 58 nm is shown in Fig 2, top left panel (insert shows long range order in the nanodots). Another form of ECM consists of fibronectin (FN) fibrils. Jens Ulmer is characterizing FN fibrilliogenesis, using an elastic topographic micro-pattern, and following the stretched fibers using scanning EM and fluorescence microscopy (insert, Fig 2, top right panel). The organization and stability of the FN matrix is also studied by Tova Volberg, who characterized the de-stabilization of FN network, using a FN fragment, known as anastellin (Fig 2, bottom). Another insight into the matrix, associated with the cell surface, was obtained by Miriam Cohen (in collaboration with Lia Addadi and Derk Joster), who studied the properties of surfacebound hyaluronan, and cell adhesion mediated by the hyaluronanbased pericellular matrix. These studies demonstrated that early stages of cell-surface interaction, preceding the integrin-dependent adhesion, are mediated by a hyaluronan gel.
Fig. 2
Top. left: Nano-pattern of RGD-coupled gold dots, with typical spacing of 58 nm (from J. Spatz); Top, right: Fibrils of bovine serum FN, formed between PDMS posts (10 μm height, diameter of 5 μm and inter-spacing of 3 μm). Samples where either immunostained with polyclonal anti-FN antibody (insert) or critical point dried and examined by SEM. Bottom panel: Effect of anastellin treatment (20μM, 6 hours) on FN fibrils (right), formed by Porcine aortic endothelial cells, compared to untreated control culture (left).
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