Relation between microcurrent therapy and satellite cells in the regeneration of induced skeletal muscle injury in rat

Severe injuries in skeletal muscle result in muscle weakness, which delays recovery and contributes to progressive decline in muscle function. Microcurrent therapy is a novel treatment method used in soft-tissue injury and tissue regeneration therapy. The regenerative capacity of skeletal muscle tissue resides in satellite cells, the quiescent adult stem cells. The present work aimed at investigating the possible relation between microcurrent therapy and satellite cells in regeneration of induced skeletal muscle injury in albino rats. Twenty-four male albino rats were divided into 2 groups: Control group and experimental group [II]: rats were subjected to gastrocnemius-soleus muscle injury [subgroup IIa], they were subdivided into subgroups IIa1 and IIa2 sacrificed 1 and 3 weeks after injury respectively. Subgroup IIb: Rats were subjected to muscle injury and micro-current electric stimulator, was applied for 20 minutes for three sessions per week. The animals were subdivided into subgroups IIb1 and IIb2 sacrificed 1 and 3 weeks following the day of injury. Muscle sections were stained with hematoxylin and eosin, alpha smooth muscle actin [alpha-SMA] and CD34 immunostaining. Morphometric studies and statistical analysis were performed. Atypical fibers were widely separated by connective tissue cells and revealed partial loss of striations in subgroup IIa. Some fibers recruited strong acidophilic sarcoplasm with focal vacuolations in subgroup IIa1. In subgroup IIb1, some typical fibers, some centrally located nuclei, and a few deeply acidophilic fibers were found. Striations were found in some areas of the sarcoplasm. In subgroup IIb2 striations were found in most areas of the sarcoplasm. A significant decrease in the mean area of atypical fibers, a significant increase in the mean area% of alpha-smooth muscle actin-positive cells, and a significant increase in the mean area% of CD34-positive cells were found in subgroup IIb compared with subgroup IIa. A definite therapeutic effect of the microcurrent was found on induced skeletal muscle injury, which was time dependent. This effect was proved to be related to satellite cell activation