The host immune response against foreign materials, also known as the foreign body response, poses a significant challenge for implanted biomaterials and medical devices. Macrophages and dendritic cells play a crucial role in the immune response. Thus current efforts are being made to modulate their activity and behaviour in vivo. We hypothesize that surface topography in the biological scale (nanometer to micrometer range) can modulate macrophage function, specifically phagocytosis, without necessitating the use of bioactive agents. In our study, we investigate the effect of topography using a novel, nanostructured glassy film, synthesized through the deposition of 2-50 nm of silicon dioxide on pre-stressed polystyrene. The glassy film is further subjected to high heat, inducing substrate shrinkage. The compressive stress of the shrinking substrate induces the formation of complex structures on the material surface. Murine bone marrow-derived macrophages were subsequently seeded onto the surfaces and incubated with Streptococcus pneumoniae bacteria to evaluate the effect of topography on macrophage phagocytosis. Fluorescent images showed increased phagocytic ability of macrophages cultured on the structured surfaces in comparison to flat surfaces. Both the extent and homogeneity of bacterial uptake improved in macrophages cultured on the glassy films. It was concluded that surface topography can passively modulate macrophage behaviour in vitro and serves as a promising avenue of study for the future development of novel biomaterials.
By Annie Wu