A splice variant of IGF-1 produced by damaged muscle tissue — activates satellite cells for muscle repair.
Mechano Growth Factor (MGF) is a splice variant of IGF-1 that is produced locally in muscle tissue in response to mechanical stress (exercise) or damage. Unlike systemic IGF-1 (produced by the liver), MGF acts in an autocrine/paracrine manner — meaning it works locally at the site of production.
MGF's primary function is activating muscle satellite cells — the stem cells responsible for muscle repair and growth. When muscle is damaged through exercise or injury, MGF is rapidly expressed, triggering satellite cell proliferation and differentiation into new myonuclei that can repair and enlarge muscle fibers.
The E-domain of MGF (the C-terminal extension unique to this splice variant) is believed to be the active component responsible for satellite cell activation. This E-peptide has been synthesized independently for research purposes.
Research demonstrates MGF is expressed rapidly (within hours) after muscle damage, preceding the expression of other IGF-1 isoforms. It uniquely activates satellite cells without promoting differentiation — maintaining the stem cell pool while initiating the repair process. In aged muscle, MGF expression is significantly reduced, contributing to impaired repair capacity.
Synthetic MGF has a very short half-life in circulation (minutes) due to rapid degradation, leading to the development of PEG-MGF (PEGylated version) with extended activity. Local injection into damaged muscle may provide the best pharmacological effect.
📚 Key Reference: PMID: 12855822 (MGF splice variant discovery)
Limited human data. Short half-life limits systemic exposure. Local injection site reactions possible. Same IGF-1 family cancer concerns apply theoretically. Research use only. Consult your provider.
NOT FDA-approved. Research use only. WADA prohibited.