Interleukin-15 (IL-15) is a novel anabolic factor for skeletal muscle which inhibits muscle wasting associated with cancer. IL-15 overexpression can induce a hypertrophic myotube morphology similar to that described for cultured myotubes which overexpresse the well-characterized anabolic factor insulin-like growth factor-I (IGF-I). However, in contrast to IGF-I, the hypertrophic action of IL-15 on skeletal myogenic cells does not involve stimulation of skeletal myoblast proliferation or differentiation. IL-15 can induce myotube hypertrophy at both low and high IGF-I concentrations. Furthermore, in contrast to IGF-I, which stimulates only protein synthesis under these culture conditions, IL-15 both stimulates protein synthesis and inhibites protein degradation in cultured skeletal myotubes.
Therefore igf-1 might be superior because of its ability to stimulate proliferation and differentiation of satellite cells which is the first step to muscle repair and hypertrophy. The only distinct effect IL-15 has is its inhibitory effects on protien degradation as both IL-15 and igf-1 increase protien synthesis, this inhibitory effect on protien degredation is useless to us unless you were putting your body in catabolic conditions in which this product would protect against muscle loss.
