Research Paper Advance Articles

Figure 2. FGF21 localizes to atrophic myofibers in ALS muscle. (A) Tissue sections from two ALS patients and one normal control were immunostained with an anti-FGF21 antibody and counterstained with DAPI and wheat germ agglutin (WGA). Intense immunoreactivity is observed in atrophic myofibers (asterisks) and in the endomysial space (arrows) in the ALS muscle sections. Scale bars, 100 μm in low power views and 50 μm in the enlarged views. (B) Mean fluorescence Intensity (MFI) analysis of FGF21 immunoreactivity was performed in 5 ALS patient biopsy samples and 5 normal controls. Atrophic (< 25 μm minimal Feret’s diameter) and non-atrophic myofibers were selected in the same section as shown in the micrograph (yellow outline). FGF21 MFI (per μm²) was quantitated for 46 atrophic and non-atrophic myofibers and summarized in the graph (horizontal line represents the mean). ****P < 0.0001; two-tailed Mann Whitney test. Scale bar: 50 μm.