PEG-MGF
Also known as: Pegylated Mechano Growth Factor, PEG-IGF-1 Ec
Evidence: Anecdotal
Overview
PEGylated version of mechano growth factor (the IGF-1Ec splice variant), sold as a research chemical; no published pharmacology or human data exist for the PEGylated form.
PEG-MGF is a grey-market PEGylated form of the synthetic IGF-1Ec E-domain peptide (MGF, id 54). No pharmacokinetic, efficacy or safety study of the PEGylated form has been published in any species, so the claims of extended half-life and systemic availability are vendor assertions, not measurements. The unmodified peptide it is built from is itself disputed: the original proliferative result (Yang 2002) failed to replicate across two pharmaceutical companies at up to 500 ng/mL (Fornaro 2014), and no endogenous MGF peptide has been isolated from cells, medium, tissue or fluid (Matheny 2010). FDA names Mechano growth factor pegylated (PEG-MGF) in the withdrawn-nomination table of its 503A compounding safety-risk page, stating it has identified no human exposure data for the substance by any route.
Benefits
No published effect of any kind for the PEGylated form. The parent peptide increased myoblast proliferation in vitro (contested; a two-company replication found no effect) and was neuroprotective in gerbil brain ischemia (animal)
Dosing reference
- Research dose
- 200 to 500 mcg: vendor and community range, no published human or animal dose for the PEGylated form
- Range
- 200 to 500 mcg, 2-3x weekly
- Reconstitution
- 1 mL bacteriostatic water
- Common vial sizes
- 2 mg, 5 mg
No published human or animal data for the PEGylated form; doses are community convention. IGF-family signaling raises theoretical concerns about hypoglycemia and promotion of existing tumors - avoid with active or suspected malignancy.
Mechanism
Sold as the MGF E-domain peptide conjugated to polyethylene glycol. The proposed mechanism is the parent peptide's: increased myoblast proliferation with delayed differentiation through a receptor other than IGF-1R (Yang 2002). That effect is contested, since a two-company replication found none up to 500 ng/mL (Fornaro 2014), and no endogenous peptide matching MGF has been isolated from any biological source (Matheny 2010). For the PEGylated form specifically, nothing is published: no conjugation chemistry, no site of attachment, no clearance measurement, no activity assay. PEGylation generally slows proteolysis and renal clearance, but whether that holds here, and at what cost to potency, has not been tested.
Evidence
Anecdotal: no peer-reviewed data
- No study of PEG-MGF has been published: no pharmacokinetics, no efficacy, no toxicology, in any species
- The parent peptide increased myoblast proliferation and inhibited differentiation in vitro, with the effect surviving IGF-1 receptor blockade (Yang and Goldspink, 2002)
- A replication across two pharmaceutical companies found no effect of MGF peptide up to 500 ng/mL on human or mouse myoblasts or primary muscle stem cells, and no p-ERK activation in cardiac myocytes (Fornaro et al., 2014)
- No analogous peptide product of the IGF-1 gene has been isolated from cultured cells, conditioned medium, animal tissue or biological fluid (Matheny et al., 2010)
- Human-trial status: none for the PEGylated form or the parent peptide. FDA states it has identified no human exposure data for PEG-MGF administered by any route
References
- Different roles of the IGF-I Ec peptide (MGF) and mature IGF-I in myoblast proliferation and differentiation. Yang SY, Goldspink G, FEBS Letters, 2002
- 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. Fornaro M, Hinken AC, Needle S, et al., American Journal of Physiology. Endocrinology and Metabolism, 2014
- Minireview: Mechano-growth factor: a putative product of IGF-I gene expression involved in tissue repair and regeneration. Matheny RW Jr, Nindl BC, Adamo ML, Endocrinology, 2010
- A strong neuroprotective effect of the autonomous C-terminal peptide of IGF-1 Ec (MGF) in brain ischemia. Dluzniewska J, Sarnowska A, Beresewicz M, et al., FASEB Journal, 2005
- Expression of IGF-I splice variants in young and old human skeletal muscle after high resistance exercise. Hameed M, Orrell RW, Cobbold M, Goldspink G, Harridge SD, The Journal of Physiology, 2003
Side effects
No data exist for the PEGylated form in any species, and FDA states it has identified no human exposure data for PEG-MGF by any route. Repeated PEG exposure carries its own uncertainty, including anti-PEG antibody formation. Hypoglycemia is the risk usually cited for IGF-1 family peptides through insulin receptor cross-reactivity, but the E-domain peptide is not IGF-1 and its reported effects were IGF-1R-independent, so that concern is inferred rather than measured. Proliferative signaling makes use with active or suspected malignancy inadvisable.
Storage
- Storage
- Refrigerate 2-8°C (36-46°F)
- Lyophilized
- 2+ years at room temp, 3+ years refrigerated
- Reconstituted
- 28-30 days refrigerated
Pharmacology
- Half-life
- Not measured for the PEGylated form or for the parent peptide. Both figures in the old value were unsourced
- Sequence
- YQPPSTNKNTKSQRRKGSTFEERK (24 aa IGF-1Ec E domain) plus an undisclosed PEG conjugate