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 SiO 2 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.