Educational reference, not medical advice. This page summarizes information from published research and regulatory filings for educational purposes. It is not a recommendation to use any compound and should not replace guidance from a licensed healthcare provider. Most peptides discussed here are not approved for the uses described.
What it is
MGF — Mechano Growth Factor — is the colloquial name for the IGF-1 Ec splice variant: an alternatively spliced isoform of the IGF-1 gene whose hallmark is a unique C-terminal "E-domain" peptide. The full IGF-1 Ec precursor contains the mature IGF-1 sequence plus an extension of 24 amino acids; the standalone E-domain peptide is often referred to in the research literature as "MGF-E" or simply "MGF."
The variant was characterized in the 1990s by Geoffrey Goldspink and colleagues at University College London, who noticed that skeletal muscle subjected to mechanical loading or damage upregulated this particular splice form much more than the systemic IGF-1 Ea variant produced by the liver. Hence "mechano growth factor": an IGF-1 isoform whose expression is gated by mechanical stimulus and tissue injury.
History
The Goldspink lab published a series of papers in the late 1990s and early 2000s describing differential splicing of IGF-1 in stretched and damaged muscle. The 2001 review by Goldspink and Yang in International Journal of Sport Nutrition and Exercise Metabolism set out the conceptual framework: a single IGF-1 gene producing distinct isoforms with distinct biological roles.
Subsequent work by Kandalla and colleagues in 2011 showed that synthetic MGF-E peptide activates satellite cells (the resident muscle stem cells) in culture and accelerates regeneration after injury in young muscle, but is less effective in aged tissue. Riddoch-Contreras and colleagues reported neuroprotective effects in the SOD1(G93A) mouse model of amyotrophic lateral sclerosis, and Mavrommatis and colleagues described cardioprotective effects of the E-domain peptide in myocardial infarction models.
No Phase II human trial of MGF has been published.
Regulatory status
MGF has no approved medical use anywhere in the world. It is sold as a research reagent under not-for-human-use labeling. The World Anti-Doping Agency lists IGF-1 and its splice variants and analogs under S2 of the Prohibited List, prohibiting use in competitive sport in and out of competition.
The peptide most commonly sold as "MGF" by research-chemical suppliers is the synthetic 24-amino-acid E-domain peptide rather than the full IGF-1 Ec precursor.
How researchers describe its action
The published literature describes two related modes of action. First, the full IGF-1 Ec precursor is processed to mature IGF-1, which engages the type-1 IGF receptor like any other IGF-1 isoform. Second, the cleaved E-domain peptide has receptor-independent effects in cell culture, including activation of satellite cells, modulation of MAPK signaling, and reduction of apoptosis in stressed cells. The molecular target of the E-domain peptide has not been definitively identified.
The mechanistic case for MGF rests largely on cell-culture and rodent injury models. The proposed link between mechanical loading, MGF upregulation, and muscle hypertrophy or repair has been examined in human exercise biopsy studies, but exogenous MGF administration has not been tested in controlled human trials.
Half-life and dosing intervals
The synthetic E-domain peptide is small and unstable in plasma; published estimates of its circulating half-life are very short, on the order of 5 to 7 minutes. This is one reason why a so-called "PEG-MGF" variant (the E-domain peptide conjugated to polyethylene glycol) is also marketed by research suppliers — pegylation slows renal clearance and proteolytic degradation.
There is no established human dose for either form. In animal studies, intramuscular doses of the E-domain peptide on the order of 25 to 100 micrograms have been used. Observational non-medical use is typically reported in the 100 to 200 mcg range per administration, with sites rotated to match the muscle group targeted — but these patterns have no clinical-trial basis.
Reconstitution example
MGF is sold as a lyophilized powder, often in 2 mg or 5 mg vials. A 2 mg vial reconstituted with 2 mL of bacteriostatic water yields 1 mg/mL — meaning 0.1 mL on a 1 mL insulin syringe (10 units on a U-100 syringe) contains 100 mcg. For a 5 mg vial reconstituted with 2 mL, the same 10-unit mark contains 250 mcg. Vial's calculator handles the unit-to-mcg conversion automatically when you enter the vial mass and water volume.
What to know
- Limited human data. Almost all efficacy evidence is from cell culture and rodents. No Phase II human trial has been published.
- Very short half-life. The synthetic E-domain peptide is cleared from circulation within minutes; PEG-MGF is the pegylated longer-lived variant.
- Banned in sport. WADA prohibits IGF-1 and its splice variants under S2.
- Storage. Lyophilized MGF is stable refrigerated and most stable frozen for long-term storage. Once reconstituted, refrigerate and use within the stability window quoted by the supplier (typically 1 to 2 weeks for the unmodified peptide).
- Naming confusion. "MGF" in supplier catalogs almost always refers to the 24-amino-acid E-domain peptide, not the full IGF-1 Ec precursor. The two molecules have different pharmacology.
Sources
- 1.Goldspink G, Yang SY (2001). Method for Determining the Expression of Mechano Growth Factor and Its Implications for Tissue Engineering and Sport Performance. International Journal of Sport Nutrition and Exercise Metabolism.
- 2.Kandalla PK, Goldspink G, Butler-Browne G, Mouly V (2011). Mechano Growth Factor E peptide (MGF-E), derived by alternative splicing of IGF-1, is activated upon injury and stimulates muscle progenitor cells. Mechanisms of Ageing and Development.
- 3.Riddoch-Contreras J, Yang SY, Dick JR, Goldspink G, Orrell RW, Greensmith L (2009). Mechano-growth factor, an IGF-I splice variant, rescues motoneurons and improves muscle function in SOD1(G93A) mice. Experimental Neurology.
- 4.Mavrommatis E, Shioura KM, Los T, Goldspink PH (2013). The E-domain region of mechano-growth factor inhibits cellular apoptosis and preserves cardiac function during myocardial infarction. Molecular and Cellular Biochemistry.
- 5.World Anti-Doping Agency — Prohibited List, S2 Peptide Hormones, Growth Factors, Related Substances and Mimetics.