Some embodiments provide a method of treating skeletal muscular myopathy, e.g., Duchenne muscular dystrophy (DMD), with cardiosphere-derived cells (CDCs), wherein a therapeutically effective amount of CDCs is delivered to a targeted dystrophic skeletal muscle. Some embodiment enable delivery of a therapeutically effective amount of CDCs via intramuscular injection directly at a skeletal muscle or systemic administration, intravenous injection, in a single dose or multiple doses, to treat a targeted dystrophic skeletal muscle. Some embodiments provide a method for improving exercise capabilities in DMD patients. Additional embodiments relate to exosome, mediated transfer of noncoding RNAs ameliorates Duchenne muscular dystrophy by restoring dystrophin in heart and skeletal muscle. Delivery of noncoding RNA species found in CDC-derived exosomes mimics the ability of CDCs and CDC-derived exosomes to increase dystrophin protein levels.