FIG. 6.

Effects of UBC-MSC CM on osteoclastogenesis and MLO-Y4 cells in vitro. Bone marrow macrophages (BMMs) were isolated from C57BL/6 mice and cultured with macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL) in the absence (CM 0) or presence of hUCB-MSC CM (CM 0.5× and CM 1×). Representative tartrate-resistant acid phosphatase (TRAP)-stained osteoclasts (scale bars, 100 μm) (A) and the number of TRAP-positive multinucleated cells isolated *p<0.01 versus CM 0. (B). (C) MLO-Y4 cells were observed with a scanning or transmission electron microscope (SEM or TEM) after treatment with vehicle (CM 0) or 0.5×hUCB-MSC CM (CM 0.5×) for 72 h. Scale bars, SEM=50 μm, TEM=1 μm. Average lengths of dendrite (D), ratio of mitochondria (white arrow) to cytosol area (E), and ratio of autophagosome (black arrow) to cytosol area (F) were calculated. *p<0.01 versus CM 0. To investigate the effects of CM on cellular apoptosis of MLO-Y4 cells, the cells (2×10³ cells/well) were plated and cultured for 24 h in the presence or absence of dexamethasone and/or hUCB-MSC CM (0.5× or 1×) as indicated. Cell viability was quantified with the MTT calorimetric assay. Data are the means±SD, and the graphical results are representative of three independent experiments, each performed in triplicate. *p<0.01 versus Dexa+CM 0 (G). Color images available online at www.liebertpub.com/tea