Figure 6.

MEK inhibition promotes tibial fracture-healing in Col2.3Cre; Nf1^flox/−mice in vivo. Tibial fractures were generated for WT and Col2.3Cre;Nf1^flox/− mice. Osmotic pumps containing either vehicle control (PBS) or PD98059 were implanted subcutaneously in the contralateral dorsal flank of Col2.3Cre;Nf1^flox/− mice. WT mice received vehicle control (PBS) implants. (A) Showing are representative radiographs acquired at 0, 14, 21, 28 days post-fracture in WT mice with PBS vehicle and Col2.3Cre;Nf1^flox/− mice with or without PD98059 (10 mg/kg/day). (B, a) Representative photomicrographs (20×) of MacNeal's/Von Kossa counter stain shows accumulation of cartilage and infiltration of marrow cells filling the fracture area in the control pump group. (B, b) Representative photomicrographs (20×) of TRACP stains are shown. Red area represents TRACP-positive-staining osteoclasts. (C) TRACP-positive osteoclasts to the bone surface ratio (Oc.N/BS) was enumerated as shown (***P < 0.01). (D) The ratio of bone volume/tissue volume was quantified to calculate percent tissue mineralization (***P < 0.01). (E) The number of OBLs per bone surface (Ob.N/BS) was quantified as shown (**P < 0.01).). Data represent mean ± SEM from five mice per treatment group.