Influence of nanopillar arrays on fibroblast motility, adhesion and migration mechanisms

Abstract

Surfaces decorated with high aspect ratio nanostructures are a promising tool to study cellular processes and design novel devices to control cellular behaviour, perform intracellular sensing or deliver effector molecules to cells in culture. However, little is known about the dynamics of cellular phenomenon such as adhesion, spreading and migration on such surfaces. In particular, how these are influenced by the surface properties. In this work, we investigate fibroblast behaviour on regular arrays of 1 micrometer high, polymer nanopillars with varying pillar to pillar distance (array pitch).NIH-3T3 fibroblasts spread on all arrays, and on contact with the substrate engulf nanopillars independently of the array pitch. As the cells start to spread, different behaviour is observed. On dense arrays which have the pitch equal or below 1 micrometer, cells are suspended on top of the nanopillars, making only sporadic contact with the glass support. Cells stay attached to the glass support and fully engulf nanopillars during spreading and migration on the sparse arrays which are characterized by a pitch of 2 micrometers and above. These alternate states have a profound effect on cell migration rates, which are strongly reduced on nanopillar sparse arrays. Dynamic actin puncta colocalize with nanopillars during cell spreading and migration. Strong membrane association with engulfed nanopillars might explain the reduced migration rates on sparse arrays. This work reveals several interesting phenomenon of dynamical cell behaviour on nanopillar arrays, and provides important perspectives on design and applications of high aspect ratio nanostructures.

Cellular nanointerface of vertical nanostructure arrays and its applications

“…The cytoskeleton, especially F-actin, regulates the transfer of the mechanical force between nanostructures and the nucleus. 24,49,95 Studies on nuclear deformation and mechanical coupling between the cell membrane and the nucleus showed that vertical nanostructure-induced nuclear deformation is determined by nuclear stiffness, as well as the opposing effects from actin and intermediate laments. The nuclear membrane deformation induced by vertically protruding nanostructures can activate nuclear mechanical conduction, change the nuclear morphology, and even cause gene expression changes.…”

“…At low densities, the cell membrane comes into contact with the substrate, allowing the nanoneedle to be completely engulfed through endocytosis. 24,104 3.1.4 Cell migration. The cells' adhesion on the nanostructures is the rst step for the cellular response to the nanointerface and other fundamental functions.…”

“…6. 24 Cells' migration is related to the actin on the cytomembrane, and the actin recruitment was transient on both dense and sparse nanoarrays. While on the sparse nanoarrays, F-actin is assembled for a longer time, 12,101 so that the migration of cells on sparse nanoarrays was restricted on the sparse nanoarrays.…”

“…Images presented are representative of n $ 50 cells for both dense and sparse arrays. 24 Reprinted with permission Copyright 2019, Small. adhesion, morphology, and division.…”

“…When the cells come in contact with nano-needle arrays initially, the nano-needle arrays with different densities and modications can also cause different cell behavior changes, such as adhesion, 20,21 diffusion, and migration, 22,23 which need systematic study. Therefore, cells can be articially regulated or promoted into specic functional cells by designing nanostructures with different structures and functions, 24 which could be further applied for applications such as regulating cell signal transmission, guiding cell migration, 25,26 stimulating stem cell differentiation, 27,28 promoting the maturation of osteoblasts, regulating the activity of macrophages, etc. Measurements of biomolecules inside cells usually require the insertion of nanoprobes (mainly as solvated, in the solid state, or as photonic crystals) through the cell membrane, or placing the nanoprobes very close to the cell membrane.…”