Effect of Exercise on Stem Cells in Skeletal Muscle It is well known that exerci

Question

Effect of Exercise on Stem Cells in Skeletal Muscle It is well known that exercise, especially strength training, helps to maintain muscle m Muscles that cannot contract due to diseases such as muscular dystrophy or that are not u to sedentary behavior show muscle fibers that strengthen and increase the size of the muscle. ass. sed due atrophy. Exercise, on the other hand, may result in formation of new Studies within the past 10 years have clearly demonstrated that stem cells are present in skeletal muscle tissue. Shown below are data from one of these studies. 14 12 10 4 2 Sed Ex Figure 1. Quantitation of skeletal muscle mesenchymal stem cells in the sedentary state (Sed) and 24 hours post exercise (Ex). Data are means 1 SE. Taken from Valero et al. 2012. PloS ONE 7 e29760 1. Describe the data..what are the results? Be sure to use statistics terminology in your description. 2. What might these results suggest about the relationship between stem cells in skeletal muscle tissue and the beneficial effects of exercise?

Explanation / Answer

1. Mesenchymal stem cells are multipotent adult stem cells that can be form different tissues like myocytes (muscle), chondrocytes (cartilage), osteoblasts (bone) and adipose cells. The experiment measure the % number of these mesenchymal stem cells in the skeletal muscle. The cells were isolated from tissues under two conditions: animals at rest (t=0) and animals at 24 hr post completing a single bout of downhill running exercise (t=24hr). The skeletal muscles were dissected and the mesenchymal stem cells were isolated by flow cytometry. Skeletal muscle mesenchymal stem cells express specific markers such as Sca1 but lacked CD45.

The data indicates that mesenchymal stem cells population increased significantly (p<0.05) in the skeletal muscle after exercise as compared to the skeletal muscle in sedentary condition. Data is represented as mean ± standard error. There was very less deviation in the data for both conditions.

2. Skeletal muscle contains mesenchymal stem cells that are capable of regenerating the muscle fibers. When the animals are subjected to exercise, these stem cells are stimulated to proliferate and self renew. They will not only form myocytes, but will also self renew and divide to increase in numbers. When the animals are at rest, the stem cells are not stimulated. Hence, their numbers will remain the same. During exercise, the muscles are subjected to stress. There is decreased amount of oxygen to the muscle tissue during exercise, promoting anaerobic respiration in the cells. As a result, strain will affect the myocytes, resulting in death. Myocytes are not capable of cell division as they are terminally differentiated. During the period of rest after exercise, the mesenchymal stem cells will be stimulated to repair the damage and differentiate into myocytes to increase myocytes number. This will ultimately increase the muscle tone. Hence, exercise will cause development of new muscle fibers.

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