MGF

Overview

Mechano Growth Factor (MGF) is a splice variant of IGF-1 (the IGF-1Ec isoform in humans, IGF-1Eb in rodents) produced in skeletal muscle in response to mechanical load, exercise, and muscle damage. Unlike systemic IGF-1 which drives myoblast differentiation, MGF specifically activates satellite cell proliferation through a receptor distinct from IGF-1R. It expands the pool of muscle stem cells before differentiation signals arrive, representing the first response to mechanical injury. Pegylated MGF (PEG-MGF) is a stabilized research form with extended half-life.

Mechanism of Action

MGF's C-terminal E-domain peptide (MGF-Ct24E) acts through a receptor that is distinct from IGF-1R — it does not displace radiolabeled IGF-1 (IC50 >10,000 nM) and does not activate Akt via IGF-1R pathway at physiological concentrations. Instead, it keeps satellite cells in a proliferative state (expanding Pax7+ pool) without driving premature differentiation. In mechanically loaded myoblasts, endogenous MGF mRNA peaks at 2 hours post-stretch (3.2-4.4× increase), preceding systemic IGF-1 induction (peak 6-8 hours). Sequential use (MGF first, then IGF-1 LR3) produces the largest myotube formation.

Potential Benefits

• Satellite cell pool expansion for muscle repair and growth
• Mechanosensitive response mimicry enabling ex vivo satellite cell activation
• Enhanced muscle regeneration after injury (18-22% higher tetanic force recovery)
• Synergistic combination with IGF-1 LR3 for complete hypertrophy program
• More satellite cells available during recovery (34-42% greater centronucleation at day 7)
• Heart muscle and neural tissue protective effects in some studies

Research Dosage Notes

The following reflects doses used in published research studies. This is not medical advice.

Research: 200-400 mcg PEG-MGF subcutaneously post-workout in human protocols; 1-5 mg/kg in animal models. Timing relative to IGF-1 LR3 is mechanistically important (MGF first).

Amino Acid Sequence

Side Effects & Safety

• Limited human safety data
• Possible insulin-like hypoglycemic effects at high doses
• PEG addition may reduce immunogenicity but add theoretical toxicity concerns
• Injection site reactions

Synergistic Compounds

The following compounds have been studied alongside MGF for potential complementary or synergistic effects:

Related Peptides

Learn More

References & Further Reading

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