FIG. 1.

Ectopic bone formation at 6 weeks after intramuscular transplantation. (A–C) Radiographic examination revealed the presence of ectopic bone at implantation sites of bone morphogenetic protein 4–secreting muscle-derived stem cells (MDSC-B4) but not at implantation sites of MDSCs transduced with a retroviral vector–expressing LacZ reporter gene (MDSC-Lac) in each scaffold group. (D–F) Deposition of mineralized matrix within the thigh muscles receiving MDSC-B4 implants detected using von Kossa histological staining. Original magnification: ×40. Color images available online at www.liebertonline.com/ten.