A novel quantitative morphometry approach to assess regeneration in dystrophic skeletal muscle.
Duchenne muscular dystrophy is an inherited degenerative muscle disease with progressive weakness of skeletal and cardiac muscle. Disturbed calcium homeostasis and signalling pathways result in degeneration/regeneration cycles with fibrotic remodelling of muscle tissue, sustained by chronic inflammation. In addition to altered microarchitecture, regeneration in dystrophic muscle fibres is often only classified by centrally located nuclei but correlation of the regeneration process to nuclear volumes, myosin amounts, architecture and functional quality are missing, in particular in old muscles where the regenerative capacity is exhausted. Such information could yield novel regeneration-to-function biomarkers. Here we used second harmonic generation and multi photon fluorescence microscopy in intact single muscle fibres from wild-type, dystrophic mdx and transgenic mdx mice expressing an Δex 17-48 mini-dystrophin to determine the percentage of centronucleated fibres and nucleus-to-myosin volume ratio as a function of age. Based on this ratio we define a 'biomotoric efficiency' as an optical measure for fibre maturation, which is close to unity in adult wild-type and mini-dystrophin fibres, but smaller in very young and old mdx mice as a result of ongoing cell maturation (young) and regeneration (aged). With these parameters it is possible to provide a quantitative measure about muscle fibre regeneration.
['Buttgereit|Andreas|A|', 'Weber|Cornelia|C|', 'Friedrich|Oliver|O|']
D000367:Age Factors D000818:Animals D015153:Blotting, Western D007090:Image Interpretation, Computer-Assisted D021621:Imaging, Three-Dimensional D008810:Mice, Inbred C57BL D018101:Mice, Inbred mdx D008822:Mice, Transgenic D036641:Microscopy, Fluorescence, Multiphoton D018485:Muscle Fibers, Skeletal D018482:Muscle, Skeletal D009137:Muscular Dystrophy, Animal D012038:Regeneration D025801:Ubiquitin
Regeneration Muscular dystrophy Myosin Second harmonic generation Efficiency Myonuclear domain Nucleus