Fig. 2.

The 3T3 fibroblasts proliferation, polarization, cytokine secretion, and relative mRNA expression levels of RAW264.7 cells incubated with the extracts of PLGA-based microspheres at 37 °C for 4 days. (a) The 3T3 fibroblasts' proliferation on each group characterized by the CCK-8 assay for 1 and 4 days at 37 °C. (b) The immunofluorescent images of RAW cells in each group and (c)–(e) the flow cytometry results of surface markers (CCR7 and CD206) of polarized RAW cells. It was obvious that the increased proportion of the M2 phenotype and decreased ratio of the M1 phenotype were observed on the PLGA/MgO-alendronate microsphere group. (f)–(i) The cytokine productions of TNF-α, IL-6, IL-1β and IL-10 secreted by RAW cells measured by ELISA kits and (j)–(m) the relative mRNA expressions of macrophage surface markers (iNOS, Arg 1) and osteogenic growth factors (BMP-2, TGF-β1) normalized to GAGDH. The control group was denoted as macrophages incubated in the normal DMEM. * represented the significantly difference (p < 0.05); ** (p < 0.01). (surface marker iNOS, CCR7: green, M1 phenotype; surface marker Arg 1, CD206: red, M2 phenotype; DAPI: blue, nuclei). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)