MGF (Mechano Growth Factor): Dosage, Reconstitution & the Replication That Failed

MGF at a glance

What it is

The 24-amino-acid C-terminal E-domain peptide of IGF-1Ec, a splice variant of IGF-1 upregulated in muscle after loading or injury. Named 'mechano growth factor' by Goldspink and Yang after the stimulus that induces the transcript.

Researched for

Satellite-cell activation and local muscle repair in the original work. The largest current body of research on this exact peptide is oncology, where it is studied as a tumour-associated marker and drug target rather than a repair agent.

The replication problem

Fornaro et al. 2014, working at Novartis and GSK, tested synthetic MGF peptide up to 500 ng/mL in C2C12 cells, primary human myoblasts, primary mouse muscle stem cells and cardiac myocytes. It failed to increase proliferation, failed to delay differentiation and failed to activate p-ERK, while IGF-1 and full-length IGF-1Eb worked in the same assays.

Commonly reported range

200-400 mcg per injection in community reports, with a wider span of roughly 100-600 mcg. No trial of any kind establishes a dose for this peptide.

Route reported

Local intramuscular injection into the trained or injured muscle, on the rationale that the native transcript acts as an autocrine/paracrine signal rather than a circulating hormone.

Plasma half-life

Never measured. No published pharmacokinetic study reports a half-life for the MGF E-peptide in any species. A figure of '5-7 minutes' previously appeared on this page and has been withdrawn — see the half-life section.

Regulatory status

Not FDA-approved. Prohibited in sport at all times by WADA under class S2. Research use only.

Not the same as PEG-MGF

PEG-MGF is this peptide with polyethylene glycol chains attached. It is covered in a separate guide; dosage, half-life claims and the anti-PEG immunogenicity question belong there.

Reported ranges from research/community — examples, not recommendations.

What it is / mechanism

MGF is not a separate gene product. The IGF-1 gene is alternatively spliced, and one of its variants — IGF-1Ec in humans, IGF-1Eb in rodents — is preferentially transcribed in skeletal muscle after mechanical loading or damage. A reading-frame shift in the E-domain of that transcript produces a distinct C-terminal sequence. When the precursor is processed, the mature 70-amino-acid IGF-1 protein is cleaved from a 24-amino-acid C-terminal peptide, and it is that C-terminal fragment, not the whole splice variant, that is sold as 'MGF'. The original proposal, from Goldspink and Yang's work in the early 2000s, was that this E-peptide has activity of its own, separate from IGF-1: that it drives quiescent satellite cells into the cell cycle and delays their fusion into myotubes, expanding the pool of muscle stem cells available for repair, and that it does so through some receptor other than IGF-1R, since the effect was reported not to be blocked by IGF-1 receptor antibodies. That model — MGF expands the satellite pool, systemic IGF-1 later drives differentiation — is the mechanism every commercial page describes. It is important to be clear about the status of that model. The receptor was never identified. In more than two decades since the peptide was named, no binding partner has been characterised, which is unusual for a signalling peptide with an ascribed physiological role. And the central cell-biology claim did not survive an independent replication attempt, described in the next section. The mechanism above is what was proposed; it is not settled biology.

Researched effects

In the original literature and in the animal and cell-culture work that followed it, the MGF E-peptide has been associated with satellite-cell proliferation, protection against apoptosis, stem-cell recruitment and local repair signalling in muscle, cardiac tissue, nerve, cartilage and bone. That literature is substantial in volume — several hundred indexed papers reference mechano growth factor — and much of it is genuine cell and tissue work. What it does not contain is a human trial. No controlled study has tested injected MGF peptide in people for muscle growth, recovery or anything else. Community reports of faster perceived recovery or a localised pump after injection are uncontrolled self-reports of a peptide whose in vitro activity has itself been contested. They are not evidence of effect, and they should not be presented as such. One strand of that literature deserves to be stated because it is systematically omitted from pages selling this peptide. The IGF-1Ec E-peptide is under active study as a cancer-associated factor: expression has been reported to rise with colonic polyp dysplasia and colorectal cancer, in endometrial carcinoma, and in prostate tumours, where IL-6 has been associated with IGF-1Ec upregulation and Ec peptide secretion. In 2024 a monoclonal antibody against the Ec peptide was developed and tested specifically to block it — anti-PEc reduced prostate cancer cell proliferation, migration and invasion, and reduced tumour size and metastasis rate in mice. That is the most active present-day research direction for this exact peptide, and its logic runs opposite to the one used to sell it: the peptide is the thing being targeted, not the therapy.

Dosage — reported ranges (overview)

There is no established dose for this peptide, because there has never been a dose-finding study of any kind — not in humans, and not as an injected agent in animals at doses that could be scaled. What circulates is community practice. Reported per-injection amounts cluster around 200-400 mcg, with a wider span of roughly 100-600 mcg. The usual description is a local intramuscular injection into the muscle trained that session, given shortly after the workout, on training days only. The reasoning offered is that the native transcript is induced locally by loading and acts as an autocrine signal, so the injected peptide should be placed where the signal is wanted and timed to the stimulus. That reasoning is internally coherent and entirely untested. It also sits on top of a claimed activity that an independent replication could not reproduce. The figures below are given because people search for them and because concentration arithmetic is useful regardless; they are not a recommendation, and they should not be read as evidence that any amount of this peptide does anything.

A printable protocol sheet with a reconstitution reference and an injection log comes with All-Access Lifetime.

Reconstitution — bac-water math

This is concentration arithmetic only, not a personal dose. MGF is dosed in micrograms, so the working figure is mcg per mL: concentration = (vial mg x 1000) / mL of bacteriostatic water. On a U-100 insulin syringe 100 units is 1 mL, so units to draw = dose (mcg) / concentration (mcg/mL) x 100. Worked example on a 2 mg vial: adding 2 mL of bacteriostatic water gives (2 x 1000) / 2 = 1,000 mcg/mL. A 200 mcg reference amount is then 200 / 1000 x 100 = 20 units on a U-100 syringe, and 400 mcg is 40 units. Every row in the table below was recomputed independently and every draw falls within a single 100-unit syringe. Add the water slowly against the vial wall and swirl gently; do not shake.

This is concentration math, not a dose recommendation.

Injection / administration basics

Community protocols describe MGF as an intramuscular injection into the specific muscle worked, using a small-gauge insulin syringe, drawn to the calculated unit mark, with sites rotated between sessions. The local rather than subcutaneous placement is the whole rationale of the reported practice, since the peptide is proposed to act where it is delivered. This describes reported handling and is not instruction for personal use; no study has validated any route or timing for this peptide.

Half-life & frequency rationale

No half-life has ever been measured for the MGF E-peptide, and a figure that previously appeared on this page has been withdrawn. This page formerly stated a native MGF half-life of 'about 5-7 minutes'. On re-checking that figure against the primary literature we could not trace it to any published measurement, so it has been removed rather than softened. A targeted search for pharmacokinetic, half-life or clearance data on the MGF peptide returns no study reporting a value in any species. The nearest published statement is from Goldspink and Yang themselves (PMID 11915923), who wrote that MGF 'has a shorter half-life in the unbound state than the systemic liver type IGF-1' — a comparative claim with no number attached, and one made about the endogenously expressed peptide rather than an injected synthetic version. We are stating the retraction rather than quietly correcting it because the number had been live on this page and had been read. If you find a specific half-life for MGF quoted elsewhere, the useful question is which study produced it. As far as the indexed literature goes, none did. The practical consequence is that the standard argument for PEGylation — that the native peptide is cleared too fast to be useful, so a PEG chain is required — rests on an unmeasured premise on both sides. That question is taken up in full on the PEG-MGF guide, where the PEGylated form's own half-life claim is examined.

Stacking — overview

The pairing most often described is MGF with IGF-1 LR3, on the original two-stage model: the E-peptide expands the satellite-cell pool, and a long-acting IGF-1 analog then drives differentiation and protein synthesis. Pairings with GH secretagogues such as GHRP-6 or a GHRH analog are described on the reasoning that raising endogenous GH and IGF-1 supports the same axis. Both rationales inherit the problem above: the first stage of the two-stage model is the stage that failed independent replication. A stack built on a mechanism that could not be reproduced is a stack of one working component and one contested one. Combination effects have never been studied for any of these pairings.

For how combinations are grouped by research context, the named blends, and why a pre-mixed blend vial cannot be calculated from its total milligrams, see the peptide stacks guide.

Storage & handling

• Lyophilized vials are described as stored refrigerated at 2-8 C and protected from light; frozen storage is described for longer holding of the sealed powder.
• After reconstitution, refrigerate at about 2-8 C, protect from light, do not freeze and do not shake. No published stability study covers this peptide in bacteriostatic water, so any 'use within X weeks' figure is handling practice rather than data.
• Bacteriostatic water is the diluent assumed throughout this page; its benzyl alcohol is what allows a reconstituted vial to be entered more than once.

Evidence File

The MGF Evidence File

The free guide gives the verdict; this module is the audit trail underneath it. Six ClinicalTrials.gov searches and the PubMed queries behind every absence claim are named verbatim, so the finding can be re-run rather than taken on trust. The 2014 replication is read for what its design forecloses rather than for its headline. Each circulating figure is followed back to the document it actually came from, the retraction notice is read in machine-readable full text for its stated reason, and the positive literature is named and weighted rather than omitted.

• 6 registry searches, 0 studies administering it
• 4 cell systems, 2 companies, 0 responses
• 1 retailer blog behind a peer-reviewed dosing table
• 25 papers in the batch that swept up the MGF retraction

Sourcing File

The MGF Sourcing File

This compound removes the check most peptide buyers rely on. The public chemistry database record that normally supplies a canonical formula and mass does not exist for it, and the federal substance register carries more than one entry under this compound's name. This module works through what is left to verify identity with: the sequence and the three authorities that agree on it, the mass arithmetic computed from that sequence with every basis stated, the substitution and degradation species that would actually be seen here, the salt arithmetic behind a labelled milligram, and a certificate read field by field with a verdict on each line.

• 0 PubChem CIDs, 2 FDA UNIIs, 1 checkable sequence
• 0.98 Da between two substances both named MGF
• 8 basic sites on a 24-residue peptide
• 174 mcg delivered from a draw calculated as 200 mcg

Benefit & Outcome Review

The MGF Benefit and Outcome Review

Ten claims circulate commercially for this peptide. Each is taken here on its own, and for each the review states the species it was measured in, the design that produced the measurement, what the comparator did in the same experiment, and who generated the material and the data. Species and design come first every time, because those are the details the marketing omits most often. Where a claim was tested and failed, it is recorded as a failure rather than as an absence; where nothing was measured, the searches establishing that are named. The register closes with what the peptide has actually been shown to do.

• 10 marketed claims reviewed, 0 rated supported
• 2 contradicted, 5 with no study of the peptide being given
• 3 plausible-unproven, none in a marketed context
• 0 human studies of the administered peptide, at any tier

Guide FAQ

Quick answers about guide scope, access, and educational use context.