Figure 4.

Lack of a direct effect of Botulinum toxin type A (BtxA) on primary bone cells. Data from three independent experiments. (a) Bone marrow macrophages (BMM) cultured in osteoclastogenic medium were exposed to varying concentrations of BtxA for 24 h. Tamoxifen (10 μM) was used as an inhibitor of osteoclastogenesis. Cell viability was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl assay. (b) BMM were cultured as in a, and stained for TRAcP-positive osteoclasts (large multinucleated cells with a minimum of seven nuclei). (c) Bone marrow stromal cells (BMSCs) were cultured in osteoblastogenic medium and exposed to different concentrations of BtxA for 24 h. Ethanol was used as an inhibitor of osteoblastogenesis. Cell viability was assessed using the MTT assay. Data were analyzed using one-way analysis of variance. No statistical differences were detected in any of the BtxA-treated cultures relative to their respective controls.