Osteoclast formation is inhibited dose dependently by 3 weeks of treatment with CC-4047 and thalidomide. (A, B) For osteoclast assays, nonadherent cells from HBM and MMBM were cultured with 10 ng/mL CSF-M and 50 ng/mL RANKL for 21 days; 0.1% DMSO (control), CC-4047, or thalidomide (Thal) was added to the culture twice a week to maintain a concentration of 100 μM. After 3 weeks of treatment, cells were fixed and stained for 23c6⁺ multinucleated OCLs. For all the micrographs, original magnification is ×20. Each value represents the mean plus or minus SD of multinucleated cells per well of at least 8 wells. All experiments were performed independently 4 times. (C) Nonadherent HBM cells were cultured with 10 ng/mL CSF-M and 50 ng/mL RANKL for 21 days and DMSO (control) at 0.1%, CC-4047 or thalidomide at 1, 25, 50, 75, 100 μM. Half-media change was performed twice a week. Following 3 weeks of treatment, cells were fixed and stained with 23c6 antibody to determine multinucleated OCLs. An asterisk indicates a significant difference from control (P < .05). MNC indicates multinucleated cells.