The role of substrate morphology for the cytokine release profile of immature human primary macrophages

There is increasing evidence that the physicochemical nature of any given material is a dominant factor for the release of cytokines by innate immune cells, specifically of macrophages, and thus majorly influences their interaction with other cell types. Recently, we could show that the 3D structure of star shaped polytheylene oxide–polypropylene oxide co-polymers (sP(EO-stat-PO))-hydrogel coated substrates has a stronger influence on the release pattern of cytokines after 7 days of culture than surface chemistry. Here, we focused on the analysis of cytokine release over time and a more detailed analysis of cell morphology by scanning electron microscopy (SEM). Therefore, we compared different strategies for SEM sample preparation and found that using osmium tetroxide combined with aqua bidest led to best preparation results. For cytokine release we show significant changes from day 3 to day 7 of cell culture. After 3 days, the sP(EO-stat-PO)-coated substrates led to an induction of pro-angiogenic CCL3 and CCL4, and of low amounts of the anti-inflammatory IL10, which declined at day 7. In contrast, pleiotropic IL6 and the pro-inflammatory TNFα and IL1β were expressed stronger at day 7 than at day 3.