MM cell line CM suppresses BMP-2–induced mineralized nodule formation and ALP activity in osteoblasts. MC3T3-E1 cells (A-B) and BM-derived osteoblasts (C) were cultured at 5 × 105 cells/mL in 24-well culture plates in the osteogenic medium described in “Patients, materials, and methods.” CM from the indicated cell lines or control media were added at 20% in triplicate in the presence or absence of rhBMP-2 (50 ng/mL). Culture media were changed every 3 days. Mineralized nodules were visualized at day 14 by von Kossa staining (A). The cells were harvested at day 10, and ALP activity of cell lysates was measured (B-C). Results are expressed as means ± SEM of triplicate experiments. * indicates significantly different by Student t tests, P < .05.
