(62ap) Macrophage Responses to Fluid Pressure: A Potential Effector at the Tissue-Implant Interface

The objective of this study was to assess the sensitivity of macrophages to fluid pressures as a first step towards identifying parameters that modulate the tissue implant interface. We hypothesized that fluid pressure at an implant interface influences macrophage activity. To address this hypothesis, we assessed superoxide production by, and the F-actin cytoskeletal organization of, HL-60 derived macrophages after a 2 h exposure to multiple pressure oscillations by varying either their mean (MP) (5?40 mm Hg), pulse pressure (PP) (0-7.5 mm Hg), or frequency (0-1.5Hz). From these experiments, we observed significantly (p<0.05) reduced superoxide production by the cells under all conditions tested. Interestingly, the reductions in superoxide release were independent of the MPs and oscillation frequencies, and instead depended on the PPs. We also observed a reorganization of the cytoskeleton in cells exposed to 20 mm Hg MP at PPs ranging from 0-7.5 mm Hg at 1.5 Hz relative to paired uncompressed controls. These results demonstrate that fluid pressure modulates macrophage activity and function at a cellular level. Pressure may be a potential parameter that plays a role in wound healing, e.g. at the tissue-implant interface.