Figure 2
Quantitative analysis of dystrophin expression in TA muscles of mdx mice after intramuscular injections of PEG-PEI-ESO polyplexes. Muscles were analyzed following 3 weekly intramuscular injections of 5 μg of ESO complexed with either PEI2K(PEG550)10, NG-PEI2K(PEG550)10, or CG-PEI2K(PEG5K)10 copolymers, and harvested 3 wks after the first injection. (A) Number of dystrophin-positive fibers for each treatment group was obtained from whole transverse sections that were immunolabeled for dystrophin. The number of dystrophin-positive fibers was significantly lower in muscles injected with NG-PEI2K(PEG550)10-ESO and CG-PEI2K(PEG5K)10-ESO polyplexes compared with the basic PEI2K(PEG550)10-ESO formulation (P < 0.05, N = 4 muscles per group). (B) Western blots show dystrophin expression in thick (60 μm) transverse cryosections taken directly adjacent to segments used for fiber counts in panel A. Images show blots of dystrophin (top) and vinculin (bottom) obtained from the same gel. All samples contained 25 μg of total protein, and dystrophin expression as a percent of normal is indicated in parentheses below each lane. (C) Quantitative western analysis of dystrophin expression as a percent of the level in age-matched normal mice for each of the three PEG-PEI-ESO polyplex formulations. No significant differences were observed between treatment groups (P > 0.05; N = 4 muscles per group).