Abrogation of the inflammatory response in LPS-stimulated RAW 264.7 murine macrophages by Zn- and Cu-doped bioactive sol-gel glasses.

The attenuation of an in vitro inflammatory response in RAW 264.7 murine macrophages stimulated with lipopolysaccharide (LPS) endotoxin was tested using sol-gel-derived bioactive glasses. Three general types of sol-gel-derived samples were evaluated: 58S, zinc-containing glasses, and copper-containing glasses. Distinct experimental procedures were used to test the potential of bioactive glasses to attenuate the inflammatory response in three situations: (1) therapeutically following LPS stimulation, (2) prophylactically before LPS stimulation of macrophages, and (3) indirectly via the glass dissolution products after stimulation with LPS. A sandwich enzyme-linked immunosorbent assay (ELISA) was used to monitor the concentration of tumor necrosis factor-alpha (TNF-alpha) secreted by macrophage cells. The strongest reduction in TNF-alpha concentration was observed when macrophage cells were first incubated with bioactive glass powder and then stimulated with LPS. This suggests a possible prophylactic application of these bioactive glasses for the prevention of inflammation. The 58S glass was capable of reducing the expression of TNF-alpha by macrophages, although the zinc- and copper-containing were more effective at suppressing the inflammatory response. The additional benefit of using zinc- and copper-doped bioactive glasses may be explained by the direct interactions of zinc and copper ions in key regulatory pathways for the inflammation response.