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PEG-MGF

Mechano growth factor

Grade D: Preclinical or anecdotal only

TL;DR: Grade D: animal/preclinical only, no human clinical trials of exogenous PEG-MGF or unmodified MGF have been published. All evidence for tissue repair, muscle regeneration, and neuroprotection effects comes from rodent models and cell culture. One human observational study measuring endogenous IGF-1 splice variants after exercise does not constitute evidence for exogenous PEG-MGF efficacy; endogenous production in response to mechanical loading is a separate phenomenon from injecting a synthetic PEGylated peptide. No human dose, pharmacokinetic, or safety data exists.

Key Takeaways

  • Grade D: Preclinical or anecdotal only
  • Not FDA approved: Not FDA-approved. Not on the 503A Bulks List. Banned by WADA under S2 (Peptide Hormones, Growth Factors, Related Substances, and Mimetics). Regulatory pathway for potential compounding access is pending PCAC review; no timeline for approval.
  • Compounding: The nomination to add PEG-MGF to the FDA 503A or 503B bulk-substances list was withdrawn; it is not on an active FDA bulks list and is not eligible for routine pharmacy compounding.

Mechanism

Mechano Growth Factor (MGF) is an alternatively spliced variant of the IGF-1 gene, generated in skeletal muscle and other tissues in response to mechanical stress or injury. The MGF-specific E-domain peptide is believed to activate muscle satellite cells (stem cells required for muscle repair), while the shared IGF-1 domain binds the IGF-1 receptor and promotes protein synthesis and cell survival. PEGylation (attachment of polyethylene glycol chains) is a pharmaceutical modification intended to slow proteolytic degradation and extend the circulating half-life of the peptide, since native MGF is very short-lived in plasma. Whether systemic injection of a PEGylated synthetic version replicates the localized, tissue-specific signaling of endogenously produced MGF is unresolved.

Evidence

Grade D: animal/preclinical only, no human clinical trials of exogenous PEG-MGF or unmodified MGF have been published. All evidence for tissue repair, muscle regeneration, and neuroprotection effects comes from rodent models and cell culture. One human observational study measuring endogenous IGF-1 splice variants after exercise does not constitute evidence for exogenous PEG-MGF efficacy; endogenous production in response to mechanical loading is a separate phenomenon from injecting a synthetic PEGylated peptide. No human dose, pharmacokinetic, or safety data exists.

Safety and risks

No human safety data exists, the risk profile is entirely unknown. Theoretical concerns include: (1) MGF signals through the IGF-1 receptor pathway, which promotes cell proliferation; uncontrolled IGF-1R stimulation is associated with tumor promotion in multiple cancer models; (2) PEGylation, used to extend half-life, can induce anti-PEG antibodies with repeated dosing, potentially causing accelerated drug clearance or, rarely, hypersensitivity reactions; (3) product purity from research-chemical or informal compounding sources is unverified and contamination risk is real. WADA bans PEG-MGF as a prohibited growth factor. Self-administration carries unquantifiable risk.

Interactions

No human data. Theoretical concern: concurrent use with insulin or IGF-1-pathway agents could compound anabolic and hypoglycemic effects. Use alongside anabolic steroids, common in the bodybuilding contexts where PEG-MGF circulates, has no safety characterization. Interaction with cancer therapies is a theoretical concern given IGF-1R pathway overlap.

Federal compounding status

Nomination withdrawn (was Category 2) as of 2026-06-02.

This substance was nominated for the FDA 503A or 503B bulk-substances list and previously sat in the Category 2 (significant safety risk) group; the nomination was later withdrawn, so it is not on an active FDA bulks list and is not eligible for routine pharmacy compounding. FDA source

Federal status only, from public FDA records. State pharmacy-board rules vary and are not covered here. This is regulatory reporting, not legal advice. All compounds.

Compounding legality

The nomination to add PEG-MGF to the FDA 503A or 503B bulk-substances list was withdrawn; it is not on an active FDA bulks list and is not eligible for routine pharmacy compounding.

Sources

  1. Overexpression of Mechano-Growth Factor Modulates Inflammatory Cytokine Expression and Macrophage Resolution in Skeletal Muscle Injury. (2018) other
  2. Improved Muscle Regeneration into a Joint Prosthesis with Mechano-Growth Factor Loaded within Mesoporous Silica Combined with Carbon Nanotubes on a Porous Titanium Alloy. (2022) other
  3. Mechano growth factor, a splice variant of IGF-1, promotes neurogenesis in the aging mouse brain. (2017) other
  4. Increased IGF-IEc expression and mechano-growth factor production in intestinal muscle of fibrostenotic Crohn's disease and smooth muscle hypertrophy. (2015) other
  5. Mechano-growth factor, an IGF-I splice variant, rescues motoneurons and improves muscle function in SOD1(G93A) mice. (2009) other
  6. The effect of anabolic steroid administration on passive stretching-induced expression of mechano-growth factor in skeletal muscle. (2013) other
  7. Minireview: Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration. (2010) review
  8. Therapeutic ultrasound decreases mechano-growth factor messenger ribonucleic acid expression after muscle contusion injury. (2007) other
  9. Mechano-growth factor peptide, the COOH terminus of unprocessed insulin-like growth factor 1, has no apparent effect on myoblasts or primary muscle stem cells. (2014) other
  10. Muscle mechano growth factor is preferentially induced by growth hormone in growth hormone-deficient lit/lit mice. (2004) other
  11. Insulin-like growth factor I (IGF-1) Ec/Mechano Growth factor--a splice variant of IGF-1 within the growth plate. (2013) other
  12. Mechano Growth Factor E peptide (MGF-E), derived from an isoform of IGF-1, activates human muscle progenitor cells and induces an increase in their fusion potential at different ages. (2011) other
  13. Growth hormone stimulates mechano growth factor expression and activates myoblast transformation in C2C12 cells. (2008) other
  14. Mechano-growth factor reduces loss of cardiac function in acute myocardial infarction. (2008) other
  15. Producing human mechano growth factor (MGF) in Escherichia coli. (2008) other
  16. Androgen-mediated improvement of body composition and muscle function involves a novel early transcriptional program including IGF1, mechano growth factor, and induction of {beta}-catenin. (2010) other

PEG-MGF is Not FDA approved. PeptideGrids presents evidence and regulatory status for informational purposes only. We do not sell, supply, source, or help anyone obtain this compound, and we provide no dosing or administration guidance. This is not medical advice; consult a licensed clinician. Full disclaimer.

Last reviewed June 1, 2026 by PeptideGrids editorial team (independently audited).