Mechano growth factor

Definition

Mechano growth factor is a splice variant of insulin-like growth factor 1, produced in skeletal muscle in response to mechanical loading and damage. It is also written IGF-1Ec, which is the name the physiology literature mostly uses, and the two names describe one thing: a locally expressed peptide whose job is to signal that a muscle has been worked.

It reaches buyers as synthetic research-use-only material, in two forms. The unpegylated peptide is what this page tracks. The pegylated form, PEG-MGF, is a separate substance in the federal record with a separate and different disposition, and the distinction is invisible on the products themselves.

Evidence

Across five name variants PubMed returns 236 indexed records, of which 134 carry the Humans subject heading, 12 the clinical-trial publication type, and 11 the randomized-controlled-trial type ^[1]. The publication-type filter was proved live in the same run against a control term returning 8,906 records under the clinical-trial type and 6,115 under the randomized type, the invalid tag returned zero for that control term, and a deliberately invalid record identifier errored in the same run ^[1].

All twelve trial-type records were opened, and not one of them administers the peptide. Every one measures how much mechano growth factor a person's own muscle expresses after an intervention: resistance training with or without recombinant growth hormone ^[2], therapeutic ultrasound applied to skeletal muscle ^[3], testosterone therapy alongside resistance exercise in older men ^[4], neuromuscular electrical stimulation, high-intensity interval training, and comparable designs ^[1]. The count is a count of exercise physiology, and the exercise is the intervention.

That distinction decides what the literature can support. A study showing that heavy loading raises expression of a locally acting splice variant establishes something about how muscle responds to loading; it establishes nothing about what happens when a synthetic version of that variant is injected, because no indexed trial has done that. The gap is not that the evidence is weak. The gap is that the evidence is about a different experiment.

Lawful access

There is no lawful United States supply route. Drugs@FDA holds no approved product with mechano growth factor as an active ingredient; the same query form in the same session returned one application for bremelanotide and fourteen for liraglutide, and returned nothing for a deliberately invented ingredient name ^[5].

The section 503A bulks list FDA published May 14, 2026 lists mechano growth factor (MGF) in Category 3 — the file for substances nominated without adequate support to evaluate ^[6]. Category 3 is not a safety finding and it is not a permission; it records that the submission behind the nomination was too thin to review. The substance appears in neither Category 1 nor Category 2 of the same document.

The pegylated form is in a different position again. PEG-MGF appears in no category of that list, because its nomination was withdrawn by its nominators; FDA's Category 2 safety-risk page still carries the concern it recorded while the nomination stood, which is that the agency identified no human exposure data for the substance by any route ^[7]. Neither form has a route, and the reasons differ. That is the whole of what separates them.

Neither form was among the seven peptides the advisory committee reviewed in July 2026 ^[6]. Both are sold as research-use-only material.

Related molecules

This molecule and PEG-MGF are the two growth factor fragments in this index and the clearest available case of one substance holding two federal dispositions; the nomination tracker files them under different headings for that reason. The human trial record prints both rows with the same reading attached, because there is one literature and it belongs to neither of them as an injected drug.

Elsewhere in this index