Role of alumina nanoporosity in acute cell response

This work studied the effect of nanoporous alumina in acute cellular response in an in vivo model. Nanoporous alumina membranes, with pore size diameters of 20 and 200 nm, were fabricated by anodic oxidation of aluminium. The membranes were thereafter characterized in terms of pore size distribution and chemical composition. To evaluate acute inflammatory response, the membranes were implanted in the peritoneal cavity of mice. Cell recruitment to the implant site was determined by fluorescence activated cell sorting (FACS) analysis. Cell adhesion to material surfaces was studied in terms of cell number, type, and morphology using scanning electron microscopy (SEM) and immunocytochemical staining followed by fluorescence microscopy. The fabricated nanoporous alumina membranes were found to have narrow pore size distribution. The in vivo study showed that 200 nm alumina membranes induced stronger inflammatory response than 20 nm membranes. This was reflected by the number of implant-associated phagocytes and the number of cells recruited to the implantation site. Since both pore-size membranes possess similar chemical composition, we believe that the observed difference in cell recruitment and adhesion is an effect of the material nanotopography. Our results suggest that nanotopography can be used to subtly control the recruitment and adherence of phagocytic cells during the acute inflammatory response to alumina membranes.