PEG-MGF
Mechano growth factor, IGF-1Ec, pegylated MGF
A splice variant of IGF-1 released by damaged muscle, sold as a local repair signal, with a thin literature that includes at least one retraction.
Preclinical only
Not approved anywhere and never entered human trials. Sold as research material.
What it is
The IGF-1 gene is spliced into more than one product. IGF-1Ec, commonly called mechano growth factor, is a variant whose expression rises in skeletal muscle after mechanical loading or damage. The appealing story is that it acts locally to recruit satellite cells and initiate repair, which would make it exercise's own regeneration signal.
PEG-MGF is a synthetic version of the C-terminal peptide with polyethylene glycol attached to slow clearance, since the unmodified peptide survives only minutes.
Why this entry is thinner than most
Because the literature is.
There is no human trial. There is no human pharmacokinetic characterisation, which matters unusually much here because the entire product concept is a modification intended to extend a half-life nobody has measured in a person.
The animal and cell literature is modest in size and has quality problems. A paper on mechano growth factor and cell apoptosis has been retracted, and other MGF work has required published corrections. A small field with retractions in it is a weaker evidence base than a small field without them, and it is worth saying so plainly rather than counting papers.
The local signalling premise cuts against the product
MGF's proposed function is autocrine and paracrine: muscle fibres make it, and it acts on satellite cells next to them, in response to that specific fibre being loaded.
If that is the mechanism, then a subcutaneous injection is the wrong intervention. Systemic delivery of a locally acting signal does not reproduce local expression at a damaged site, which is the same problem follistatin-344 has: the evidence concerns something the product does not do.
Injecting into the trained muscle, as some protocols suggest, is closer in spirit and still nothing like endogenous expression by the fibres themselves.
Practical notes
- The pegylation is unvalidated. PEG attachment is a real pharmaceutical technique with real regulatory scrutiny when done properly. On a research-grade vial, neither the degree of pegylation nor the fate of the PEG has been characterised.
- IGF-1 isoform biology intersects with cancer. Reviews of IGF-1 isoforms including IGF-1Ec in tumour biology are the reason the red flag above is mechanistic rather than boilerplate.
- Training is the intervention with the evidence. The signal this compound imitates is one that resistance exercise produces for free, in the right tissue, at the right time.
Side effects and warning signs
Commonly reported
- Injection-site irritation and localised swelling
- Unknown systemically. No human safety study exists
Stop and get medical help
- IGF-1 isoforms including IGF-1Ec are implicated in tumour biology, and injecting a mitogenic splice variant has a mechanistic risk nobody has characterised
- Any active or suspected malignancy
- Pegylation raises its own questions, since the clearance and tissue accumulation of the PEG moiety in this product have never been studied
Sources
From the community
Discussion for this compound concentrates in r/Peptides.
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