BMP9-induced ectopic bone formation from iMEFs is potentiated by Wnt3A but attenuated by β-catenin knockdown.

<p>(<b>A</b>) Gross images. Subconfluent iMEF-simBC3 and iMEF-siControl cells were infected with AdBMP9, AdWnt3A, AdBMP9+AdWnt3A, or AdGFP for 16 h. Cells were collected for subcutaneous injections (3×10⁶ cells/site in 100 μl PBS) into the flanks of athymic nude mice (n = 5 each group). At 4 weeks after injection, the animals were sacrificed. Masses formed at the injection sites were retrieved from the groups injected with the iMEF-siControl cells transduced with BMP9 (<b><i>a</i></b>) or BMP9+Wnt3A (<b><i>b</i></b>), while very small masses were retrieved from the animals injected with the iMEFs transduced BMP9+Wnt3A (c) or BMP9 (not shown). No masses were retrieved from the animals injected with Wnt3A- or GFP-transduced iMEF cells. Representative results are shown. (<b>B</b>) and (<b>C</b>) Histologic evaluation and Trichrome staining. The retrieved samples were decalcified and subjected to paraffin-embedded sectioning for histologic evaluation, including H & E staining (<b><i>B</i></b>) and Trichrome staining (<b><i>C</i></b>). Representative results are shown. TB, trabecular bone; MBM, mineralized bone matrix; OM, osteoid matrix; CM, chondroid matrix.