Amoeboid migration mode adaption in quasi-3D spatial density gradients of varying lattice geometry

Abstract

Cell migration processes are controlled by sensitive interaction with external cues such as topographic structures of the cell's environment. Here, we present systematically controlled assays to investigate the specific effects of spatial density and local geometry of topographic structure on amoeboid migration of Dictyostelium discoideum cells. This is realized by well-controlled fabrication of quasi-3D pillar fields exhibiting a systematic variation of inter-pillar distance and pillar lattice geometry. By time-resolved local mean-squared displacement analysis of amoeboid migration, we can extract motility parameters in order to elucidate the details of amoeboid migration mechanisms and consolidate them in a two-state contact-controlled motility model, distinguishing directed and random phases. Specifically, we find that directed pillar-to-pillar runs are found preferably in high pillar density regions, and cells in directed motion states sense pillars as attractive topographic stimuli. In contrast, cell motion in random probing states is inhibited by high pillar density, where pillars act as obstacles for cell motion. In a gradient spatial density, these mechanisms lead to topographic guidance of cells, with a general trend towards a regime of inter-pillar spacing close to the cell diameter. In locally anisotropic pillar environments, cell migration is often found to be damped due to competing attraction by different pillars in close proximity and due to lack of other potential stimuli in the vicinity 3 These authors contributed equally to this work. of the cell. Further, we demonstrate topographic cell guidance reflecting the lattice geometry of the quasi-3D environment by distinct preferences in migration direction. Our findings allow to specifically control amoeboid cell migration by purely topographic effects and thus, to induce active cell guidance. These tools hold prospects for medical applications like improved wound treatment, or invasion assays for immune cells.S Online supplementary data available from stacks.iop.org/NJP/16/075012/ mmedia Keywords: amoeboid migration, topographic guidance, 3D environmental structure, cell motility, cell migration assay New J. Phys. 16 (2014) 075012 M Gorelashvili et al geometry with defined density gradients, providing spatially controlled quasi-3D environments for cell migration. In doing so, we take advantage of the fact that PDMS is a comprehensively characterized standard material, which provides a well-controllable model environment for systematic cell migration studies [29,32]. To exclude surface-induced or chemically related side-effects, the pillar samples were produced from bulk material, exhibiting uniform surface structure and chemical composition. This way, we make sure that the pillars and the bottom in between them are of the same material. For all experiments the pillars are non-flexible posts of the same diameter d = 4 μm. This way, changes in the migration behavior of cells in contact with the pillar structures can be related solely to the topographi...

Chemotaxis and topotaxis add vectorially for amoeboid cell migration

“…The height and diameter of the pillars is the same (8 µm) and comparable to the typical size of a D. discoideum cell, which varies between 8-15 µm 40 . This ratio between pillar height and cell size is sufficient to keep the motion of starved D. discoideum two-dimensional, meaning the pillars act as obstacles, as observed in previous studies 38,41 . Cells fully mounting the pillars are rarely observed and excluded from the data.…”

“…Fabrication of pillar gradient structures. PDMS (Sylgard 184 Silicon Elastomer Kit, Dow Corning, MI, USA) micro-pillars were made as previously described in 41 using standard photolithography techniques. The micro-pillars were positioned in a trigonal array.…”

“…We analyzed the xytrajectories with in-house Matlab (version 2018b, The Mathworks, Inc., Natick, MA, U.S.A.) analysis program. Using the recorded displacements, and registered imaging times, we calculated movement statistics, like instantaneous velocities, turning angles and mean-square displacements (MSD), as previously published 38,41 .…”

Nanostructured surfaces of biodegradable silica fibers enhance directed amoeboid cell migration in a microtubule-dependent process

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Recovering a stochastic process from super-resolution noisy ensembles of single-particle trajectories

“…Depending on the obstacle density, crawling was found at low density of obstacles [11] and directed and random phases can even be differentiated. In high density regions, the motion is rather directed from obstacle-to-obstacle [12].…”