FSS induces osteogenic differentiation MC3T3-E1 cells.

<p>(A) FSS induced rearrangement of stress fibers. F-actin microfilaments were visualized with rhodamine phalloidin. Relative means and standard deviations of fluorescence intensity were given upon the images (<i>P</i><0.01; Scale bar: 20 µm). Transcriptional levels of <i>ALP</i> (B), <i>RUNX2</i> (C) and <i>SP7</i> (D) in MC3T3-E1 cells were determined by qRT-PCR in a series of time points after FSS. Data were shown as fold change relative to control. (E) ALP activities were detected by using nitrophenyl phosphate (PNPP) method at 24 h pf.. (F) Extracellular type I collagen was determined by immunostaining at 24 h pf.. Relative integrated optical density (IOD) of immunostaining was calculated and the relative means and standard deviations were shown under each picture. (<i>P</i><0.001; Scale bar: 50 µm) (G) Microscopic view of extracellular matrix (ECM) mineralization. Cells treated with FSS and stained with Alizarin Red S at day 12 pf. Quantification of Alizarin Red S (ARS) staining was determined via extraction with cetyl-pyridinium chloride. Absorbance was read at 560 nm. Relative means and standard deviations were shown underneath (<i>P</i><0.001; Scale bar: 50 µm). Transcriptional levels of <i>ALP</i> (H), <i>RUNX2</i> (I) and <i>SP7</i> (J), ALP activities (K) and ECM mineralization (L) in primary isolated mesenchymal stem cells from mouse bone marrow were determined after FSS treatment. (pf., post-FSS treatment. Scale bar: 50 µm. Data were shown as mean ± SD. <i>n</i> = 3; **, <i>P</i><0.001; ***, <i>P</i><0.001.)</p>