D tier · weak
A genuine, well-characterised IGF-1 splice product with reproducible effects on human muscle progenitor cells and rodent injury models, but with no human interventional trial and an authoritative review co-authored by its own discoverers stating that its efficacy in man is not proven.
mgf
MGF is the 24-amino-acid C-terminal E-domain peptide of IGF-1Ec, a splice variant of IGF-1 that is upregulated in skeletal muscle after mechanical loading and damage. Preclinical work supports a role in activating muscle satellite cells and in rodent cardiac and neuromuscular injury models, but no controlled human trial of the synthetic peptide has been published.
// we supply this one
available as a research reagent
≥ 99% HPLC · lyophilised powder · batch certificate published. Grade D above is our own and is not adjusted because we stock it.
the explanation
When muscle is stressed or damaged, the body makes a special short-lived version of the IGF-1 growth signal, and MGF is the small tail piece of that molecule. It looks genuinely interesting in human muscle cells and in animals, but nobody has published a proper human trial of the synthetic version.
regulatory status
Not approved in any jurisdiction; research chemical only
MGF holds no marketing authorisation anywhere and is not a recognised medicine in any regulatory system. The 2026 Frontiers in Endocrinology review of GH-IGF1 axis peptides lists pegylated MGF (PEG-MGF) among IGF-1 analogues commonly encountered in online self-administration protocols despite the absence of human trial data. Growth factors of this class fall within the peptide hormone and growth factor category prohibited in sport.
how it works · proposed mechanism
MGF is proposed to act as a locally released repair signal that mobilises muscle satellite cells after mechanical damage.
Load-induced alternative splicing
Mechanical overload and damage shift IGF1 splicing toward the Ec variant, in which part of exon 5 joins exon 6 and causes a reading-frame shift. The resulting transcript encodes a distinct C-terminal E-domain absent from the predominant systemic IGF-1Ea isoform.
Satellite cell activation
Review work from the group that named MGF reports that the MGF-24aa-E peptide activates satellite cells to replicate while holding them from further differentiation until they fuse with existing muscle fibres. In primary human myoblast cultures the peptide increased proliferative lifespan and fusion potential in neonatal and young adult donors.
Acts without IGF-1 core
The isolated E-domain shows activity in cardiac and neural models, including reduced apoptosis and preserved function after experimental myocardial infarction in rodents. Reported partners include 14-3-3 protein interactomes rather than classical IGF-1 receptor signalling.
what’s reported
evidence shape
5 sourcesThe composition of the cited literature by study type. This describes the shape of the evidence, not its quality — and it does not by itself set the grade.
⚠ the catch
The human E-peptide is 24 residues while most animal work uses the 25-residue version, so a substantial part of the preclinical base was generated with a different molecule from the one sold as MGF. Beyond that, the 2012 review authored by the researchers who characterised MGF states plainly that its efficacy in man is not proven while acknowledging it is nonetheless used by athletes.
key published findings
- Human cells (in vitro): Kandalla et al. (Mech Ageing Dev 2011;132:154-162) reported that MGF-E peptide significantly increased proliferative lifespan and delayed senescence in primary human muscle progenitor cells from neonatal and young adult donors, with the senescence effect absent in cells from elderly donors, and hypertrophy with a reduced percentage of reserve cells across all cultures.
- Rodent: Riddoch-Contreras et al. (Exp Neurol 2009;215:281-289) reported that mechano-growth factor rescued motoneurons and improved muscle function in SOD1(G93A) transgenic mice.
- Tissue expression (negative result): Schlegel et al. (PLOS ONE 2013;8(10):e76133) found MGF substantially expressed in growth plate tissue but reported that adding MGF peptide was not associated with growth plate chondrocyte proliferation, contrasting with the effects described in muscle.
- Sequence (human vs animal): the human MGF E-domain peptide is YQPPSTNKNTKSQRRKGSTFEEHK at 24 residues, whereas the peptide consists of 25 amino acids in the other species examined, a species difference explicitly documented by Schlegel et al. and consistent with the 25-residue C-terminus described by Zablocka et al.
- Human trials: no interventional human study of synthetic MGF appears in the indexed literature, and the 2012 Frontiers in Endocrinology review by Zablocka, Goldspink and colleagues states that its efficacy in man is not proven.
limitations of the evidence
- No human interventional trial, no human pharmacokinetics, and no quantitative half-life data exist for the synthetic peptide.
- A large share of the animal literature uses the 25-residue non-human E-peptide, which limits transfer of reported effects to the 24-residue human sequence sold as MGF.
- Negative findings sit alongside positive ones, including the absence of a chondrocyte proliferation effect in growth plate tissue, and there is no systematic review or meta-analysis to weigh the body of evidence.
documented safety signals
- No published human safety data; the 2026 Frontiers in Endocrinology review lists PEG-MGF among IGF-1 analogues self-administered without clinical evidence and documents adverse effects associated with unregulated use of this peptide class.
- Theoretical concern shared across IGF-1 axis agents: effects on proliferation of unwanted cell populations have not been evaluated in any long-term study, in either direction.
identity
| full name | Mechano growth factor (IGF-1Ec C-terminal E-domain peptide, MGF-24aa-E) |
| category | Growth Hormone |
| modality | peptide |
| formula | C121H194N40O40 |
| molar mass | 2849.1 g/mol |
| half-life | Not established. The review literature predicts a very short half-life for the endogenous E-peptide and notes that synthetic versions benefit from chemical stabilisation, but no quantitative human or animal pharmacokinetic data have been published. |
| sequence | YQPPSTNKNTKSQRRKGSTFEEHK |
laboratory handling
| storage | Supplied as a lyophilised powder; research peptide is generally stored desiccated at -20 °C and protected from light. |
| solubility | Soluble in water; the sequence is strongly basic with two arginines and three lysines, and the review literature notes that synthetic E-peptides benefit from chemical stabilisation. |
| co-studied with | No published study evaluates MGF in combination with any other compound, and the pegylated variant PEG-MGF is a distinct chemical entity with its own separate and equally absent evidence base. |
Handling information describes laboratory practice for a research reagent. It is not a preparation guide for use in humans.
the receipts
5 citedFrontiers in Endocrinology 3:131 · 2012 · review
Frontiers in Endocrinology · 2026 · review
PLOS ONE 8(10):e76133 · 2013 · preclinical
Mechanisms of Ageing and Development 132:154-162 · 2011 · preclinical
Experimental Neurology 215:281-289 · 2009 · preclinical
others in Growth Hormone