MGF

A splice variant of the IGF-1 gene (IGF-1Ec in humans, IGF-1Eb in rodents) that is expressed locally in muscle tissue in response to mechanical overload and damage. The unique C-terminal E domain distinguishes it from systemic IGF-1 and is responsible for its specific role in activating quiescent satellite cells to begin the repair and growth process.

• Unique E-domain peptide activates quiescent satellite (stem) cells in damaged muscle
• Initiates satellite cell proliferation before they differentiate (priming phase)
• Acts in an autocrine/paracrine manner within mechanically stressed muscle tissue
• Signals through the IGF-1 receptor but with distinct downstream signaling kinetics due to E-domain

• Active malignancy
• Pregnancy or breastfeeding
• Acute muscle tears (may worsen inflammation acutely)

Store at 2–8°C (36–46°F) for up to 3 months. For long-term storage, keep at -20°C (-4°F). Reconstituted solution is unstable — prepare fresh each session or refrigerate and use within 24 hours.

MGF was discovered by Dr. Geoffrey Goldspink's group at University College London. Research demonstrated that mechanical overload induces MGF expression as the initial IGF-1 splice variant before shifting to IGF-1Ea (systemic). Animal studies show MGF administration increases muscle mass by 20% within weeks. The extremely short half-life of the synthetic peptide limits practical use, leading to the development of PEG-MGF for extended activity.