Gene expression profile of macrophage-like U937 cells in response to polyethylene particles: a novel cell-particle culture system.

We investigated the gene expression profiles of U937 cells after contact with polyethylene particles. U937 cells were differentiated with phorbol 12-myristate 13-acetate, and cocultured with either retrieved polyethylene particles or commercially produced polyethylene particles (Ceridust 3615, Clariant Japan, Tokyo, Japan). To achieve consistent contact with the polyethylene particles, we used a rotating device. Phagocytosis of the polyethylene particles or retrieved polyethylene particles by differentiated U937 cells stimulated the release of cytokines including interleukin 1β, interleukin 6, interleukin 8, and vascular endothelial growth factor. Microarray analysis revealed that the expression of IL8, CCL4, CXCR4, and some other genes was up-regulated after contact with retrieved polyethylene particles. This study first reports the gene expression profiles of U937 cells after contact with polyethylene particles. We believe that this experimental model is applicable to all other particulate materials.