Fig. 1.

Decreased myoblast fusion and myotube formation in cerebral palsy (CP). A: example of a normalized differentiation assay performed over ~42 h with the iCELLigence RTCA system. Green curve represents a typically developing (TD) myoblast preparation (average of 3 wells). Blue and red curves correspond to cell preparations from two different CP children, CP1 and CP2, under the same conditions (average of 3 wells per sample). Differentiation was promoted by switching from high-serum to low-serum medium. Myotube formation is associated with a significant increase in cell impedance. B: slopes of growth curves are used to quantify the rate of fusion and myotube formation over time; ***CP vs. TD, P < 0.001; analysis by one-way ANOVA (n = 8/group). C: myoblasts from CP and TD preparations were differentiated for 42 h and stained for slow myosin heavy chain (MYH7) and a nuclear stain (4′,6′-diamidino-2-phenylindole, DAPI). CP myotubes appeared spindly, thin, and with fewer nuclei per myotube. Gray scale panels show MYH7 staining as a single channel. D: quantification of fusion index for CP and TD myoblasts. Quantification was performed after 42 h of differentiation; ***CP vs. TD, P < 0.001; Analysis by one-way ANOVA (n = 8/group).