Particulate UBM induces alterations in macrophage phenotype in vitro. (a) RT-PCR analysis of M1 (Tnfa, Il1b, Inos) and M2 (Arg1, Retnla, Il10) genes in bone-marrow derived macrophages cultured on UBM for 24 h in M0 (growth, unstimulated), M1 (inflammatory, LPS+IFNg) or M2 (anti-inflammatory, IL-4) media conditions. (b) Flow cytometric analysis of CD86 (M1), CD206 (M2) and IL4ra (M2) on macrophages at 24 h post-seeding on UBM coated tissue culture plastic (TCP). Data are means ± SEM, n = 4 mice per group.