Fig. 4

Acute cigarette smoke exposure diminished osteoblast-specific gene expression and bone mineralization at cellular and molecular levels, with additive effects when alongside LPS administration. a Smoke exposure did not alter the number of osteoblasts on the bone interface as measured by histomorphometry in the protocol 2 mice model. b The capacity of bone mineralization was measured by alizarin red staining. c Gene expression of osteoblast differentiation markers including Runx2, OSX and OPN was determined by real-time RT-PCR. Levels of Runx2, OSX, and OPN mRNA were normalized to GAPDH. d ALP activity was normalized to the total protein level. e OPG and RANKL gene expression in the differentiated BMSCs were examined by quantitative RT-PCR. The ratio of OPG to RANKL was calculated. Data are presented as the mean ± SD from triplicates. ^*P < 0.05 compared to non-smoke group; ^**P < 0.001 compared to non-smoke group; ^†P < 0.05 compared to non-smoke with LPS group