Polymer Nanopillars Induce Increased Paxillin Adhesion Assembly and Promote Axon Growth in Primary Cortical Neurons

Abstract

The complexity of the extracellular matrix consists of micro‐ and nanoscale structures that influence neuronal development through contact guidance. Substrates with defined topographic cues mimic the complex extracellular environment and can improve the interface between cells and biomedical devices as well as potentially serve as tissue engineering scaffolds. This study investigates axon development and growth of primary cortical neurons on OrmoComp nanopillars of various dimensions. Neuronal somas and neurites form adhesions and F‐actin accumulations around the pillars indicating a close contact to the topography. In addition, higher pillars (400 nm) confine the growing neurites, resulting in greater neurite alignment to the topographical pattern compared to lower pillars (100 nm). A comprehensive analysis of growth cone dynamics during axon development shows that nanopillars induce earlier axon establishment and change the periodicity of growth cone dynamics by promoting elongation. This results in longer axons compared to the flat substrate. Finally, the increase in surface area available for growth cone coupling provided by nanopillar sidewalls is correlated with increased assembly of paxillin‐rich point contact adhesions and a reduction in actin retrograde flow rates allowing for accelerated and persistent neurite outgrowth.

Culturing human iPSC-derived neural progenitor cells on nanowire arrays: mapping the impact of nanowire length and array pitch on proliferation, viability, and membrane deformation

“…In literature, it is reported that well-ordered NW arrays can generate guiding forces to polarize cells or to direct neurite growth. 41,[54][55][56][57]75,98 Many array parameters were modified in these studies, but in the end, primarily the spacing of the nanostructures was contributing decisively, and guiding only occurs within a certain range of array pitches. Nonetheless, a direct comparison can only be made with Bucaro et al because they used comparable array pitches from 0.8 to 5 µm (but only at a fixed NW length of 5 µm) to fine-tune the polarization of human mesenchymal and rodent stem cells.…”

“…[40][41][42][43] Furthermore, NW arrays have been used to measure mechanical properties, [44][45][46] to interact with the cell's nucleus, 47 to constrain movement and spreading, [48][49][50][51][52] or to direct cell polarization such as outgrowth of neurites. [53][54][55][56][57] In addition to the aforementioned passive applications, functionalized NW arrays were employed to incorporate an executing role, such as drug delivery, 29,[58][59][60][61][62][63] cell transfection, [64][65][66][67] electrical stimulation/sensing, [68][69][70][71][72] or biosensing, 73 to name a few. To address specific applications, the interaction of the cell and the NWs can be tuned by adjusting the length and diameter of the NWs and the pitch of the array.…”

Recent Developments in Surface Topography-Modulated Neurogenesis

“…Furthermore, growing neurites seemed to have a greater alignment in the higher pillars due to their stronger confinement. All in all, the topography resulted in longer axons compared to culture on flat surfaces [20].…”

“…2e) [18]. Similarly, Milos et al examined whether a different topography pattern could promote axonal growth of E18 rat embryo cortical neurons [20]. To do so, they produced a nanopillar silicon mold based on electron beam lithography of photoresist with variable diameters (500, 750, and 1000 nm) and heights (100 and 400 nm).…”

Advances in Cell-Conductive Polymer Biointerfaces and Role of the Plasma Membrane

“…Here, the stabilization of the cell–electrode interface is achieved by the topography-induced formation of organized actin rings around the stalk of the engulfed microstructure. 168 , 184 − 186 The ability of protruding electrodes to induce the shape rearrangement necessary for the cell to accommodate the pseudo-3D structures was further confirmed by recent observations on the topography-driven recruitment of curvature sensitive proteins (e.g., Bin/Amphiphysin/Rvs (BAR) proteins) at the cell–material interface, 177 , 187 as shown in Figure 7 A. Among these, F-actin typically accumulates at nanopillars tips, 188 where high positive curvature is strongly induced by the pseudo-3D geometry.…”