Figure 3.

Activin‐A inhibits osteoclast formation in cocultures. Control or FOP PLF were cocultured with CD14+ cells from a healthy subject without and with Activin‐A 50 ng/ml for 21 days on plastic and on bone. Typical micrographs of osteoclast formation on plastic in a coculture of CD14+ cells with (a) control PLF without Activin‐A (b) control PLF with Activin‐A (c) FOP PLF without Activin‐A (d) FOP PLF with Activin‐A are shown, osteoclasts indicated with arrows. Osteoclasts indicated with solid arrowheads are shown at a higher magnification in the left lower corner of the corresponding micrographs. The number of TRAcP positive multinucleated (more than three nuclei) cells were counted on (d) plastic and (e) bone and were conferred to the number of cells/cm². Activin‐A inhibits osteoclast formation in cocultures with FOP PLF. n = 6 for both control and FOP (Wilcoxon matched‐pairs signed rank test, ^* p ≤ 0.05). FOP: fibrodysplasia ossificans progressiva; PLF: periodontal ligament fibroblasts; TRAcP: tartrate resistant acid phosphatase [Color figure can be viewed at wileyonlinelibrary.com]