Mouse gastrocnemius muscle regeneration after mechanical or cardiotoxin injury

Abstract

Abstract:The goal of our study was to compare the skeletal muscle regeneration induced by two types of injury: either crushing, that causes muscle degeneration as a result of mechanical devastation of myofibers, or the injection of a cardiotoxin that is a myotoxic agent causing myolysis of myofibers leading to muscle degeneration. Regenerating muscles were analyzed at selected intervals, until the 14 th day following the injury. We analyzed their weight and morphology. We also studied the expression of different myosin heavy chain isoforms as a molecular marker of the regeneration progress. Histological analysis revealed that inflammatory response and myotube formation in crushed muscles was delayed compared to cardiotoxin-injected ones. Moreover, the expression of myosin heavy chain isoforms was observed earlier in cardiotoxin-injured versus crushed muscles. We conclude that the dynamics of skeletal muscle regeneration depends on the method of injury.

Inflammatory response during slow- and fast-twitch muscle regeneration

“…In the current study, we focused on a developmental marker of myogenesis, i.e., embryonic MyHC, which during muscle regeneration is expressed exclusively in newly formed multinucleated myotubes. The dynamics of its expression may differ, however, depending on the method of muscle injury . Nevertheless, it marks newly formed muscle fibers.…”

“…The dynamics of its expression may differ, however, depending on the method of muscle injury. 11,12,29,36,37,48 Nevertheless, it marks newly formed muscle fibers.…”

“…The characteristics and efficiency of skeletal muscle regeneration depend on the method of injury and on the type of skeletal muscle, i.e., fast‐ versus slow‐twitch. For example, freezing, notexin, or cardiotoxin induced regeneration are not accompanied by progressive replacement of muscle by fibrous tissue, but in the crush‐induced model, as applied in our study, regeneration proceeds differently in slow‐twitch and fast‐twitch muscles . Fast‐twitch muscles, such as extensor digitorum (EDL), where 95% of myofibers are of the fast type, regenerate efficiently, and the structure becomes normal at the end of the process.…”

“…For example, freezing, notexin, or cardiotoxin induced regeneration are not accompanied by progressive replacement of muscle by fibrous tissue, but in the crush-induced model, as applied in our study, regeneration proceeds differently in slow-twitch and fast-twitch muscles. 4,8,[10][11][12][13] Fast-twitch muscles, such as extensor digitorum (EDL), where 95% of myofibers are of the fast type, regenerate efficiently, and the structure becomes normal at the end of the process. In contrast, slow-twitch muscles, such as the soleus, with 80-100% of fibers of slow type, fail to properly reconstruct; their regeneration is associated with development of fibrosis.…”

The molecular mechanisms underlying sketetal and cardiac muscle remodeling in the hibernating thirteen-lined ground squirrel

“…The regulation of myomaker may depend on the severity of injury induced on the muscle, since it was up-regulated following cardiotoxin-induced injury. Cardiotoxin is a myotoxic agent that leads to the myolysis of the myofiber by inducing rapid plasma membrane depolarization and the characteristics of muscle regeneration depend on the type of injury induced (Czerwinska, Streminska, Ciemerych, & Grabowska, 2012). Therefore, the levels of skeletal muscle atrophy that the ground squirrel goes through during hibernation may not be enough to induce an increase in myomaker.…”