Coursework R: Mini-Review
Topic Selected: Topic 2: “Skeletal muscle undergoes repair and regenaration throughout normal life. Write a review on the processes involved, emphasizing the role of satellite cells.”
Muscle Cell Regeneration and the Impact of Ageing
Throughout normal life, skeletal muscles undergo repair and regeneration in response to injury through a process involving several sequential steps. A very important role in this regeneration is played by satellite cells, which are small mononuclear progenitor cells found in mature muscle tissues. In this review, we are going to explore the consequences of ageing in satellite cell numbers and their ability to maintain and preserve muscle tissue.
Steps involved when skeletal muscle is damaged:
The homeostatic process that allows muscle regeneration in response to an injury stimulus, involves four interrelated steps: degeneration, inflammation, regeneration and remodelling repair. When myofibers are damaged, extracellular calcium flows into the cell, initiating proteolysis, which causes necrosis. The necrosis of myofibers brings about an inflammatory response where neutrophils and macrophages infiltrate the injured site. Neutrophils are the first to arrive; they remove cell debris by releasing free radicals and proteases as well as secreting pro-inflammatory cytokines that stimulate the arrival of macrophages. There two different classes of macrophages arriving at the injured site: M1 (expressing CD68) and M2 (expressing CD163). The M1 class is responsible for producing a high concentration of pro-inflammatory cytokines, which promote further tissue inflammation. Arriving next, is the M2 class of macrophages that induce angiogenesis and tissue remodelling and repair, by activating stem cells. This phase of inflammation is critical to the muscle regeneration process. Experiments have shown that if the inflammation...