During muscle regeneration, new skeletal muscle fiber exhibit their nuclei centrally located and then finally matures to periphery nucleated fibers [ 3 ]. Thus the number of fiber with centrally located nuclei imputes an immature muscle and/or in regeneration phase. The maturation constitutes the third and last phase of the degeneration/regeneration cycle and is characterized by fiber hypertrophy and gradual recovery functional properties of the muscle [ 3 , 48 ]. Treatment with BMMC increased soleus muscle cross-sectional area and decreased the number of fiber with centrally located nuclei suggesting a more mature phenotype of treated muscles. Therefore, increasing the pool of cells capable of differentiating into skeletal muscle cells is a promising tool to help in the treatment of serious and recidivous/recurrent injuries as in sports, aging and car accidents. Taken together, our results suggest that bone marrow injected cells might contribute to myotube formation process (repairing damaged muscle fibers) and/or form new muscle fibers regardless of fibrosis. Alternatively, as mentioned above, paracrine secretion of growth and angiogenic factors might result in improved function through hypertrophy and angiogenesis [ 49 ].