Figure 2

Recombinant IL-15 stimulation of differentiating primary human myoblasts partially reverses TNFα-induced inhibition of myogenic differentiation of cells from both young and old individuals. Subconfluent myoblasts were switched to differentiation medium containing the indicated recombinant cytokines (IL-15, 25 ng/mL; TNFα, 1 ng/mL) for 8 d. Media were renewed every 2 d. Myotubes were fixed, immunofluorescence stained for desmin and DAPI and imaged on an epifluorescence microscope. (a) Representative images at 20x magnification. (b) Myotube thickness data represents the mean ± SEM of 450 total measurements taken at 63x magnification from 90 myotubes per treatment condition (from 3 biological replicates). (c) Nuclear fusion index data represents the mean ± SEM values from 45 images taken at 20x magnification (from 3 biological replicates). *p < 0.05, **p < 0.01, ***p < 0.001 vs. unstimulated condition by 2-way ANOVA with post-hoc Bonferroni correction.