Figure 5. Treatment of Krox20;Nf1^flox/− Mice with Imatinib Mesylate.

(A) Change in mean FDG-PET-positive tumors after a 12 week treatment with imatinib mesylate. The temporal sequence of scans in three individual mice, and the experimental treatment groups are identified (panels1–6). A schematic identifying a high resolution region of interest and representative regions of interest prior and subsequent to treatment with imatinib mesylate are shown (panels 7 and 8). (B) Summary of changes in mean FDG-PET intensity after a 12 week treatment with imatinib mesylate or PBS. Data are presented as mean ± SEM. (C) Dissection of the peripheral nerves. Mean volume of dorsal root ganglia from all sciatic nerves of Krox20;Nf1^flox/− mice treated with vehicle versus imatinib mesylate. The solid line indicates mean volume of each respective group. Each symbol indicates the volume of an individual nerve. *p < 0.001 comparing vehicle to imatinib mesylate. (D) Histological analysis of the Krox20;Nf1^flox/− mice treated with imatinib mesylate or vehicle. Representative sections were shown following H&E staining, Alcian blue staining, and Masson's trichrome staining. The experimental therapy, the stains utilized to prepare the specimens, and the magnification are indicated. Red arrows identify mast cells found on the respective sections. (E) Imatinib mesylate reduces mast cell numbers in plexiform neurofibromas. Summary data of mast cells per 100× field of Krox20;Nf1^flox/− mice treated with imatinib mesylate or vehicle. Data represent mean ± SEM of mast cells/ high power field from 10 fields of 12 tumors/DRG; an asterisk indicates p < 0.01 statistical difference between groups. (F and G) Imatinib mesylate induces apoptosis (F) and reduces proliferation (G) in plexiform neurofibromas. Summary data (mean ± SEM) of (F) apoptotic and (G) BrdU+ cells / high power field imatinib mesylate versus placebo; an asterisk indicates p < 0.01 statistical difference between groups.