Figure 2

Suppression of osteoclastic resorption activity by MK CM. (a) Tartrate-resistant acid phosphatase (TRAP) staining of osteoclasts in the presence or absence of the indicated doses of conditioned medias (CMs) for 4 days. TRAP-positive cells with more than three nuclei were counted. (b) TRAP staining of osteoclasts in the presence of the indicated doses of phorbol 12-myristate 13-acetate (PMA) for 4 days. (c) TRAP staining of osteoclasts in the presence or absence of 30% (v/v) MK and pro-MK CM fractions derived from murine fetal livers for 4 days. (d) Viability of mouse BMMϕ was assessed using a CCK-8 assay in the presence or absence of the indicated doses of CM for 48 hours. (e) TRAP staining of osteoclasts in the presence of 10% (v/v) MK and pro-MK CMs for the indicated times. (f,g) Resorption activity of osteoclasts. After the full differentiation of BMMs into osteoclasts, cells were seeded on a dentine disc with M-CSF and RANKL, and then cultured in the presence of 10% (v/v) MK or pro-MK CM for the indicated times. MK and pro-MK cells were derived from K562 cells (f) or from murine fetal livers (g). Resorbed areas were quantified as percentages of the total area. MK and pro-MK were derived from K562 cells, unless otherwise specified. Data are presented as mean ± SEM. *P < 0.05 vs. non-CM (α-MEM media); ^#P < 0.05 vs. pro-MK CM. NS, not significant.