Regeneration, hyperplasia and decrease in overall fiber size of R406W desmin expressing muscles compared to E413K expressing muscles. (A) Percentage of neonatal myosin heavy chain (MHC) expressing muscle fibers, (B) total number (dots filled bars) and c-Myc expressing (empty bar) muscle fibers, (C) Western blot quantification of c-Myc, (D) size distribution of total and (E) c-Myc expressing muscle fibers; were examined in WT (n = 3), R406W (n = 3) and E413K (n = 3) desmin expressing tibialis anterior muscles 1 month after AAV vectors injection. For all morphometric analysis, all muscle fibers in whole muscle sections were analyzed. Note the strong increase in regeneration of tibialis anterior expressing R406W desmin compared to the slight increase with E413K desmin (A). Note also hyperplasia of R406W desmin expressing muscle demonstrated after counting the exogenous desmin expressing (Myc-positive, empty bars) and the total number of fibers (dots filled bars) (B). To compare size distribution of total (D) and exogenous desmin expressing (Myc-positive) (E) muscle fibers of WT, R406W or E413K desmin muscles, the Gaussian curve was plotted and grouped. Note the overall decrease in the size of both total and exogenous desmin expressing muscle fibers in R406W muscles, and, to a much lesser extent, the decrease in the size of fibers expressing desmin E413K. Asterisks indicate a significant difference compared to the WT (*P ≤0.05, **P ≤0.01, ***P ≤0.001). AAV, adeno-associated virus; MHC, myosin heavy chain; WT, wild-type.