Also known as: IGF-1Ec, Mechano Growth Factor, PEG-MGF
Half-life: ~5-7 minutes (MGF); ~2-3 days (PEG-MGF)
Last reviewed: · Published:
Mechano Growth Factor (MGF) is the natural local splice variant of insulin-like growth factor 1 (IGF-1), formally designated IGF-1Ec in humans (IGF-1Eb in rodents). It is produced inside skeletal muscle in response to mechanical strain and damage, and unlike systemic IGF-1 it acts in a paracrine fashion at the site of injury. MGF's 24-amino-acid C-terminal "E-domain" appears to be the bioactive portion responsible for activating muscle satellite cells, promoting their proliferation, and recruiting them to fuse with damaged muscle fibers — a key step in hypertrophy and repair.
Synthetic MGF used in research replicates this C-terminal E-domain peptide rather than the full IGF-1Ec sequence. Because the unmodified peptide has a very short half-life in circulation (minutes), a pegylated version (PEG-MGF) is commonly produced to extend its activity to several days, allowing systemic dosing rather than direct local injection. PEG-MGF is the form most often sold by peptide vendors.
MGF is sometimes confused with mainstream IGF-1 analogs (IGF-1 LR3, IGF-1 DES). It is biologically distinct: where IGF-1 LR3 produces sustained systemic IGF-1 receptor activation, MGF's E-domain peptide acts on a different (and not fully characterized) receptor pathway and is specifically associated with satellite cell activation rather than general anabolic signaling. Evidence in humans is much thinner than for IGF-1 itself, with most data coming from animal models and in vitro work.
MGF was first described in the early 1990s by Geoffrey Goldspink's group at the Royal Free Hospital in London, who showed that exercising muscle produced an alternative splice form of IGF-1 distinct from the systemic liver-derived isoform. The E-domain peptide was synthesized and tested in animal models throughout the late 1990s and 2000s, demonstrating accelerated muscle repair and hypertrophy after injury. Pegylated synthetic MGF (PEG-MGF) emerged in the research peptide market in the mid-2000s. Despite promising preclinical results, no human clinical program has carried MGF to regulatory approval.
Short-term tolerability of MGF and PEG-MGF in research and self-experimentation reports is generally good at typical doses, with the most common complaint being mild injection-site reactions. Because MGF activates pathways that drive cell proliferation, theoretical concerns exist around growth of any tissue with the right receptor profile — particularly relevant for anyone with undiagnosed neoplasia. Human safety data are limited and any chronic use should be approached with caution.
Dose Range
200-300 mcg per site
Frequency
Post-workout, into the worked muscle (intramuscular)
Duration
3-4 weeks per cycle
Dose Range
200-400 mcg
Frequency
Twice weekly (SubQ)
Duration
4-6 weeks per cycle
Dosing information is for educational purposes only. Consult a healthcare professional before using any peptide.
Typical Vial Size
2 mg
Water Type
Bacteriostatic water (BAC water)
Mixing Volume
1-2 mL
Half-Life
~5-7 minutes (MGF); ~2-3 days (PEG-MGF)
Molecular Weight
~2,867 Da (E-domain peptide)
Store reconstituted vial refrigerated at 2-8°C. Use within 14 days for non-pegylated MGF; PEG-MGF is more stable and can be used for up to 30 days. Localized intramuscular injection directly into the worked muscle within ~1 hour post-training is the traditional protocol for non-pegylated MGF.
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FDA Status
Not FDA approved for any indication.
Legal Status
Unregulated research chemical. Prohibited by WADA.
USA
Not approvedResearch-only; sold as a research chemical
EU
Not approvedNot authorized as medicinal product
UK
Not approvedClassified as research chemical
Australia
Not approvedTGA has not authorized
Canada
Not approvedNot authorized for human use
Goldspink G
Physiology (2005)
Comprehensive review by the discoverer of MGF describing how mechanical strain triggers alternative splicing of the IGF-1 gene to produce IGF-1Ec (MGF), and how the resulting peptide regulates satellite-cell activation and muscle adaptation.
View Study →Hill M, Goldspink G
Journal of Physiology (2003)
Demonstrated that synthetic MGF E-domain peptide (and its pegylated form) activate muscle satellite cells and accelerate repair following damage in animal models.
View Study →Yang SY, Goldspink G
FEBS Letters (2002)
Showed that the C-terminal E-domain peptide of MGF, administered locally to skeletal muscle, increased muscle fiber cross-sectional area in mice via satellite-cell activation — establishing the bioactive role of the E-peptide independent of the IGF-1 portion.
View Study →Selective growth hormone secretagogue with minimal side effects.
Long-acting growth hormone releasing hormone analog for sustained GH and IGF-1 elevation.
FDA-approved GHRH analog for HIV-associated lipodystrophy with potent GH-releasing activity.
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