F tier · safety concern
An exact-phrase PubMed search for 'PEG-MGF' returns exactly one indexed publication — a 2026 endocrinology review which states there are 'no peer-reviewed clinical studies in humans' — and zero records exist for 'pegylated mechano growth factor'; ClinicalTrials.gov returns zero registered studies. Every mechanistic claim made for the product belongs to unmodified MGF or to endogenous IGF-1Ec, and the pegylation is precisely the change that blocks transfer of that evidence.
peg-mgf
PEG-MGF is a polyethylene-glycol conjugate of the 24-residue C-terminal E-domain peptide of IGF-1Ec, the mechanical-load-induced splice variant of IGF-1. No study of the pegylated construct has been published in any species: the single PubMed-indexed source that mentions it is a 2026 review confirming the absence of human clinical data and noting that the effects observed with native IGF-1Ec or unmodified E-domain peptides cannot be assumed to apply to a PEG conjugate. This index grades unmodified MGF at D on the strength of its cell and rodent work; PEG-MGF has no separate evidence base at all.
// we supply this one
available as a research reagent
≥ 98% HPLC · lyophilised powder · batch certificate published. Grade F above is our own and is not adjusted because we stock it.
the explanation
PEG-MGF is the MGF muscle-repair peptide with a chain of polyethylene glycol stuck onto it, which is supposed to make it last longer in the body. Nobody has ever published a study on that pegylated version — not in people, not in animals, not even in cells. Every claim you read about it is really a claim about plain MGF, or about IGF-1, and adding the PEG is exactly the sort of change that makes borrowed results stop applying.
regulatory status
Not approved anywhere; no defined chemical entity, no clinical development, prohibited in sport
PEG-MGF holds no marketing authorisation from the MHRA, EMA, FDA or any other regulator, has never been the subject of a registered clinical trial, and has no investigational or orphan designation. In the UK it is an unlicensed substance with no medicinal authorisation, it is not a controlled drug, and it is not a lawful food-supplement ingredient; lawful supply is as a research chemical not for human use. The 2026 WADA Prohibited List names 'Mechano growth factors (MGFs)' in the plural under S2.3, so both the unmodified peptide and pegylated derivatives are prohibited at all times, in and out of competition. The 2026 endocrinology review that constitutes its entire indexed literature lists it among GH-IGF1-axis peptides circulating in self-administration protocols without clinical evidence. FDA has scheduled a Pharmacy Compounding Advisory Committee meeting before the end of February 2027 to consider whether this substance should be added to the section 503A bulks list. A committee recommendation is non-binding and confers no approval; implementation would require notice-and-comment rulemaking, which the FDA bar estimates at twelve to twenty-four months or longer.
how it works · proposed mechanism
Everything described as the mechanism of PEG-MGF is the mechanism of something else — either the endogenous IGF-1Ec splice product or the unmodified synthetic E-domain peptide.
The peptide half is plain MGF
Mechanical overload shifts IGF1 splicing toward the Ec variant, whose distinct C-terminal E-domain is 24 residues in humans. The satellite-cell and repair claims trace to work on that unmodified peptide in primary human muscle progenitor cultures and rodent injury models, and to endogenous expression studies, not to any pegylated form.
What pegylation actually changes
Covalent PEG conjugation enlarges hydrodynamic radius, slows renal filtration and shields the peptide from proteolysis. Approved PEGylated biologics use linear or branched PEG reagents up to 40 kDa, a mass more than an order of magnitude greater than a 24-residue peptide, so in such a conjugate the PEG dominates size, distribution and clearance.
Why the borrowed data cannot transfer
The 2026 review states that pegylation 'fundamentally alters pharmacokinetics and tissue exposure, such that biological effects observed with native IGF-1Ec or isolated E-domain peptides cannot be assumed to apply to PEG-conjugated constructs'. The proposed action of MGF is local, transient and load-triggered, which is the profile a long-circulating conjugate is least likely to reproduce.
Not a defined molecule
No supplier publishes PEG molar mass, linker chemistry, conjugation site or degree of substitution. The peptide carries four lysine side-chain amines and a free N-terminal amine, giving five plausible amine-directed attachment points, so nominally identical vials can contain different positional isomers and different PEG loads. That is why no molar mass, molecular formula or CAS number can honestly be stated for it.
what’s reported
evidence shape
7 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
PEG-MGF has no evidence base of its own — not thin evidence, none. One indexed publication mentions it, and that publication exists to say no clinical studies of it have been done. Every claim attached to the name is borrowed twice over: from the unmodified 24-residue E-peptide tested in cell culture and rodents, and from full-length IGF-1 biology behind that. The borrowing fails on its own terms, because the pegylation that is the product's entire selling point is exactly what changes pharmacokinetics and tissue exposure enough that E-peptide results cannot be assumed to carry across, and because a substantial part of the underlying animal literature used the 25-residue non-human E-peptide rather than the 24-residue human one. Compounding all of it, no vendor states the PEG size, linker or attachment point, so two vials labelled PEG-MGF need not contain the same substance, and no molar mass or CAS number can be assigned to it at all.
key published findings
- Literature search result: an exact-phrase PubMed search for 'PEG-MGF' returns one record, Dominikowski et al., Frontiers in Endocrinology 2026 (doi 10.3389/fendo.2026.1822475), and a search for 'pegylated mechano growth factor' returns zero records.
- That review states PEG-MGF has 'no peer-reviewed clinical studies in humans', that 'the rationale behind PEGylation (as promoted commercially) is to increase molecular stability and prolong exposure', that pegylation 'fundamentally alters pharmacokinetics and tissue exposure, such that biological effects observed with native IGF-1Ec or isolated E-domain peptides cannot be assumed to apply to PEG-conjugated constructs', and concludes that 'claims that PEG-MGF reliably accelerates recovery or improves body composition in humans remain unproven'. It also names the borrowing explicitly: 'the mechanistic literature most often cited in support of "MGF-like" regenerative effects is largely based on IGF-1Ec/MGF biology and synthetic E-domain peptide constructs, rather than on PEG-MGF as a clinically characterised drug entity'.
- Source of the borrowed data: Kandalla et al. (Mech Ageing Dev 2011;132:154-162) used the unmodified synthetic MGF E-peptide in primary human muscle progenitor cell culture, and the 2012 Frontiers in Endocrinology review co-authored by MGF's own discoverers states that its efficacy in man is not proven.
- A species and sequence problem inherited from the parent peptide: Schlegel et al. (PLOS ONE 2013;8(10):e76133) documented that the human E-domain peptide is 24 residues while it is 25 residues in the other species examined, and separately reported that adding MGF peptide was not associated with growth-plate chondrocyte proliferation — a negative result within the borrowed evidence base.
- Registry result: ClinicalTrials.gov returns zero studies for 'PEG-MGF'. The single registered study matching the exact phrase 'mechano growth factor' (NCT03087292, blood-flow-restricted low-intensity resistance training in coronary heart disease) measures MGF as a circulating biomarker and administers no peptide at all.
- Pegylation is not inert: in a review of the 12 approved PEGylated biologics, PEG reagents ranged up to 40 kDa and cellular vacuolation, seen microscopically mainly in phagocytic cells, occurred with 5 of the 12 products.
limitations of the evidence
- Zero studies exist on the actual substance in humans, animals or cells — there is no evidence to weigh, only evidence about a related molecule.
- The chemistry is undefined: without a published PEG molar mass, linker, attachment site or degree of substitution, no molecular formula, molar mass or CAS number can be assigned, and batch-to-batch identity cannot be verified even in principle.
- The borrowed evidence is entirely in vitro or rodent, includes at least one negative tissue result, and a substantial share used the 25-residue non-human E-peptide rather than the 24-residue human sequence.
- No analytical chemistry or doping-control literature describes seized or purchased PEG-MGF preparations, so nothing independently establishes what products under this name contain.
- The single source that mentions the compound is a narrative review of self-administration patterns rather than an experimental study; it is the best available reference only because nothing better exists.
documented safety signals
- No human or animal safety data exist for PEG-MGF. Absence of reported harm reflects the complete absence of study, not evidence of safety.
- The 2026 review records a theoretical proliferative concern for this class based on IGF-1Ec/MGF expression in cancer biology, alongside an explicit absence of human adverse-event data.
- The PEG moiety carries its own known findings: cellular vacuolation in phagocytic cells was observed with 5 of 12 approved PEGylated biologics, and no such assessment has ever been performed for a PEG-MGF conjugate.
- Because the conjugate is chemically undefined, immunogenicity cannot be predicted or compared between products; no supplier publishes characterisation data that would allow it.
identity
| full name | PEGylated mechano growth factor — a polyethylene-glycol conjugate of the IGF-1Ec C-terminal E-domain peptide |
| category | Growth Hormone |
| modality | peptide |
| half-life | Not established in any species. No pharmacokinetic study of PEG-MGF has ever been published, so the prolonged exposure that pegylation is commercially claimed to deliver has never been measured for this construct. |
laboratory handling
| storage | Lyophilised powder is stored desiccated at -20 °C and protected from light. Once reconstituted, laboratory practice is refrigeration at 2-8 °C for short-term use, or aliquoting and freezing to avoid repeated freeze-thaw cycles. Handling information only; this material has no approved human use. |
| solubility | Short hydrophilic peptide, readily soluble in sterile or bacteriostatic water and in dilute aqueous buffer. Lot-specific solubility is stated on the certificate of analysis. |
| co-studied with | No combination study exists, and none is possible to interpret when the single-agent evidence base is empty. PEG-MGF is typically sold beside unmodified MGF (graded D in this index), IGF-1 LR3 (F), IGF-1 DES (F) and hGH fragment 176-191 (F); the pegylated form is a distinct chemical entity from MGF and inherits none of its data. |
Handling information describes laboratory practice for a research reagent. It is not a preparation guide for use in humans.
the receipts
8 citedClinicalTrials.gov, US National Library of Medicine · 2017 · official
World Anti-Doping Agency (official list text as published for 2026) · 2026 · official
Frontiers in Endocrinology (Dominikowski A, Rękoś Z, Olejarz M, et al.) · 2026 · review
Frontiers in Endocrinology 3:131 (Zablocka B, Goldspink PH, Goldspink G, Gorecki DC) · 2012 · review
Journal of Pharmaceutical Sciences 105:460-475 (Turecek PL, Bossard MJ, Schoetens F, Ivens IA) · 2016 · review
Mechanisms of Ageing and Development 132:154-162 (Kandalla PK, Goldspink G, Butler-Browne G, Mouly V) · 2011 · preclinical
PLOS ONE 8(10):e76133 (Schlegel W, Raimann A, Halbauer D, et al.) · 2013 · preclinical
U.S. Food and Drug Administration · 2026 · regulatory
others in Growth Hormone