The Topography of Silica Films Modulates Primary Macrophage Morphology and Function

Abstract

Macrophages are major contributors to the rejection of foreign materials introduced to living tissues. Given that cell‐surface interactions can have important effects on phagocytic capacity and cytokine production, changes in macrophage morphology have been reported for different materials and surface patterns. However, the details of how surface topography impacts morphology and function remain unclear. This study investigates whether changes in the surface topography of glassy substrates alter macrophage shape and modulate phagocytic function and the secretion of pro‐inflammatory cytokine IL‐6. The morphology of murine bone marrow–derived macrophages cultured on micro‐ and nanostructured SiO2 films is quantified through fractal analysis. It is observed that membrane protrusions increase on nanostructured surfaces and macrophages adopt unique star‐shaped morphologies on microstructures. Macrophages on both micro‐ and nanostructured surfaces display greater phagocytic capacity, compared to those on flat controls. In contrast, the secretion of pro‐inflammatory cytokine IL‐6 is not increased when cells are cultured on the structured surfaces. The diffusion of a transmembrane receptor is also measured, which reveals no impact of structuring or plasma treatment on receptor diffusion. Altogether, these data indicate that surface topography does not increase IL‐6 production or alter membrane mobility but can significantly impact phagocytosis.

Image Analysis of Structured Surfaces for Quantitative Topographical Characterization

“…The application of Fourier analysis for periodic feature size determination could be used to quantify how changes in material preparation parameters affect resulting properties including but not limited to elastic modulus, hydrophobicity or hydrophilicity, conductivity, adhesion, fouling, stretchability, and optical properties. Specifically, accurate characterization of periodic feature size could be applied to many areas of study including the extraction of mechanical moduli from buckled films; [15,16,22,23] assessment of how drying or crosslinking parameters affect the topography of wrinkled hydrogel systems; [43] analysis of cell growth, proliferation, and alignment as a function of surface topography; [44,45] quantification of the effect of structure size on anti-fouling properties; [26] and the characterization of current and resistance of stretchable electronics as a function of wrinkle size. [24]…”

Engineering Nanopatterned Structures to Orchestrate Macrophage Phenotype by Cell Shape

“…Growing evidence has revealed that morphology is heavily associated with phenotype in certain macrophages; however, the phenomenon may not be universal. We and others have observed that while M2-polarized RAW264.7 exhibited well-spread cell shape, other macrophages did not display such dramatic changes [ 25 , 26 , 27 ]. Likely contributing to conflicting reports were several factors, including the differences between murine and human macrophages used in different reports, and the sensitivity of macrophages to different substrates including polymers, ceramics and metals [ 28 , 29 , 30 , 31 ].…”

In Vitro Effect of Replicated Porous Polymeric Nano-MicroStructured Biointerfaces Characteristics on Macrophages Behavior

“…It has been reported that topography design and size scale profile induce specific morphological cellular responses that can modulate macrophage activity [ 49 , 50 , 51 , 52 ]. Distinctive morphologies of primary human macrophages were observed on nano- and micro-textured PVDF surface with a correlation with inflammatory activity [ 16 ].…”