MGF

MGF (Mechano Growth Factor) is a splice variant of insulin-like growth factor-1 (IGF-1) produced locally in muscle tissue in response to mechanical overload or damage. When muscles are subjected to intense exercise or physical stress, the IGF-1 gene is alternatively spliced to produce MGF rather than the systemic form of IGF-1. This localized production plays a crucial role in the initial phases of muscle repair and adaptation.

The primary mechanism of MGF involves activation of muscle satellite cells, the resident stem cells of skeletal muscle. When released in response to muscle damage, MGF stimulates satellite cells to proliferate and fuse with existing muscle fibers. This is distinct from systemic IGF-1, which primarily promotes differentiation of already-activated satellite cells. MGF provides the initial signal to mobilize the muscle repair machinery.

Research has shown that MGF production declines with age, which may contribute to sarcopenia. Studies comparing MGF expression in young versus old muscle following exercise have demonstrated significantly reduced MGF response in aged muscle. This has led to interest in exogenous MGF as a strategy for combating age-related muscle decline.

Synthetic MGF and its PEGylated form (PEG-MGF, with a longer half-life) have been studied in animal models showing enhanced muscle repair following injury. However, unmodified MGF has a very short half-life of only minutes in circulation, which led to PEG-MGF development. Human clinical data remains very limited.