Fig. 4. The anti-dystrophin humoral response and loss of muscle dystrophin expression was delayed in mdx mice treated with high dose irradiation followed by dystrophin gene transfer using a high-capacity adenoviral vector.

(A) Sera from mdx mice that 1) were irradiated at 900 rads and received an intramuscular injection of dystrophin vector (IR + DYS+B10 BM), 2) were irradiated and received B10 BM only (IR+B10 BM), 3) received an intramuscular injection of dystrophin vector without irradiation (no IR + DYS), or 4) received neither irradiation nor dystrophin vector (untreated mdx) were incubated with membrane-immobilized dystrophin protein. Sera were collected from treated and control mice at 4, 8, and 12 weeks (Wk) after treatment (n=5 for IR+DYS+B10 BM and n=3 for all control groups). No serum indicates a negative control without mouse serum labeling. DYS-2 indicates a positive immunoblotting control using a monoclonal anti-dystrophin antibody as the primary antibody. All experimental samples and representative control samples are presented here. (B) Dystrophin-expressing fibers per TA muscle section were counted for all experimental mice shown in (A) and all untreated mdx control mice. Dystrophin-expressing fibers were labeled on muscle cryosections using an anti-dystrophin monoclonal antibody and were counted per cryosection of treated TA muscles. The percentages on the bars for each time point indicate the average percentage of dystrophin-expressing fibers per total fibers per section. Muscle cross-sections of each vector-injected and uninjected TA muscles were analyzed and the mean of the fibers counted in sections from treated and control mice were calculated. Dystrophin-expressing fibers were counted to be 10%, 20%, and 5% of total muscle fibers per section at weeks 4, 8, and 12, respectively. Data is expressed as mean ± standard error (SE). *(P<0.05) and **(P<0.001) indicate significant differences from untreated mdx control.