Induction of specific macrophage subtypes by defined micro-patterned structures

In this study, we investigated the influence of different perfluoropolyether (PFPE) microstructures on the inflammatory response of human macrophages. We generated four different microstructured PFPE surfaces by replica molding from silicon masters. The function-associated surface markers 27E10 and CD163 were monitored using flow cytometry to measure the pro- and anti-inflammatory reactions. Inflammatory mediator expression was measured at the protein and mRNA level. Lipopolysaccharide treatment served as positive control for pro-inflammatory activation. We observed that each micropattern induced a specific morphology, phenotype and mediator profile. A microstructure of regular grooves induced a pro-inflammatory phenotype (M1) which was not accompanied by release of pro-inflammatory mediators. However, the larger cylindrical posts induced an anti-inflammatory phenotype (M2) with a remarkable down-regulation of CXCL10. Smaller posts with a shorter distance exhibited a stronger pro-inflammatory response than those with a longer distance, on the levels of both phenotype and mediator release. Regression analysis suggests that the geometrical parameters of the microstructures, specifically the period of structures, may play an important role in macrophage response. Optimization of such microstructures may provide a method to invoke a predictable response of macrophages to implants and control the mediator release.