MGF vs PEG-MGF: What PEGylation Changes and the Evidence
MGF vs PEG-MGF at a glance
| Fact | MGF | PEG-MGF |
|---|---|---|
| Also known as | Mechano growth factor, IGF-1Ec | Pegylated mechano growth factor, Mechano growth factor, pegylated |
| What it is | Peptide based on mechano growth factor, an isoform of insulin-like growth factor 1 (IGF-1) | Pegylated form of mechano growth factor (MGF), an isoform of insulin-like growth factor 1 |
| Evidence level | Preclinical (lab and animal studies) | Preclinical (lab and animal studies) |
| Approved products | None | None |
| United States | Not FDA-approved; FDA lists mechano growth factor (MGF) in Category 3 (nominated without adequate support) for pharmacy compounding [7][8]. | Not FDA-approved; the compounding nomination for PEG-MGF was withdrawn after FDA said it may pose a significant risk of immune reactions for some routes of administration and found no human exposure data, and FDA plans to consult its advisory committee on it before the end of February 2027 [7][5][14]. |
| United Kingdom | No UK-licensed medicine containing mechano growth factor (MGF) appears in the MHRA products database [9]. | No UK-licensed medicine containing PEG-MGF appears in the MHRA products database [15]. |
| European Union | No medicine containing mechano growth factor (MGF) is authorized in the EU, according to EMA's central and Article 57 product data [10][11]. | No medicine containing PEG-MGF is authorized in the EU, according to EMA's central and Article 57 product data [10][11]. |
| Canada | No product containing mechano growth factor (MGF) appears in Health Canada's Drug Product Database [12]. | No product containing PEG-MGF appears in Health Canada's Drug Product Database [12]. |
| Australia | Mechano growth factor is not named in Australia's Poisons Standard (October 2026), which lists insulin-like growth factors in Schedule 4 with Appendix D possession controls [13]. | PEG-MGF is not named in Australia's Poisons Standard (October 2026), which lists insulin-like growth factors in Schedule 4 with Appendix D possession controls [13]. |
| Sport (WADA) | Mechano growth factors (MGFs) are named under S2 of the 2026 Prohibited List and banned at all times [6]. | Mechano growth factors (MGFs) are named under S2 of the 2026 Prohibited List and banned at all times [6]. |
| Vendors we track | 9 vendors | 14 vendors |
| Our lab tests | None yet | None yet |
MGF (mechano growth factor) and PEG-MGF are both sold as research peptides based on the same natural molecule, an isoform of insulin-like growth factor 1 (IGF-1) [1, 3]. The difference is chemical: PEG-MGF is marketed as MGF with polyethylene glycol (PEG) chains attached, a change meant to make it more stable and longer-lasting [3]. That change matters for the evidence. Effects seen in studies of MGF can’t be assumed to carry over to PEG-MGF, and a 2026 review found no peer-reviewed human studies of PEG-MGF at all [3].
What each one is
The IGF1 gene produces several precursor forms of IGF-1 through alternative splicing. In humans these are called IGF-IEa, IGF-IEb and IGF-IEc; each carries an extra tail, the E-peptide, which is cut off when mature IGF-1 is made, and some of these isoforms and E-peptides appear to have biological activity of their own [2].
MGF corresponds to one of these splice variants, often referred to as IGF-1Ec [3]. It is described as a mechanically sensitive growth factor that responds to mechanical stimuli [1]. Much of the research cited for “MGF” used either the natural IGF-1Ec isoform or synthetic peptides based on its E-domain [3].
PEG-MGF is marketed as a PEGylated form of MGF [3]. PEGylation means attaching PEG chains to a protein or peptide. It increases the molecule’s size and shields it from the enzymes that break peptides down; without it, many peptide drugs are degraded quickly, cleared rapidly by the kidneys and have a short half-life [4]. The commercial rationale for PEG-MGF is to increase stability and prolong exposure [3].
How the evidence compares
The evidence for MGF is preclinical. Cell and animal studies link it to the behavior of cartilage cells, but a 2023 review described its role in cartilage development and disease as still controversial and its mechanism as still elusive [1]. Experimental studies of synthetic MGF E-domain peptides report effects in muscle-cell transplantation and heart-injury models in animals [3]. The same 2026 review concludes that the evidence base is predominantly preclinical and that robust randomized trials in humans are lacking [3].
For PEG-MGF, the gap is larger. The 2026 review placed it in its lowest evidence tier: no peer-reviewed human studies, with claims resting on extrapolation from preclinical work [3]. It also cautions that PEGylation fundamentally alters a compound’s pharmacokinetics and the tissues it reaches, so effects observed with native IGF-1Ec or isolated E-domain peptides cannot be assumed to apply to PEG-conjugated versions [3]. FDA has not identified any human exposure data for drug products containing PEG-MGF, given by any route [5].
Regulation and sport
As the table above shows, neither is an approved medicine in the markets we track. FDA had placed PEG-MGF in category 2 of compounding substances that may present significant safety risks, but the nomination was later withdrawn [5], and WADA bans mechano growth factors in sport at all times [6].
Quality risks when buying
FDA says compounded drugs containing PEG-MGF may pose a significant risk of immune reactions (immunogenicity) for certain routes of administration, and may involve complexities with peptide-related impurities and with characterizing the active ingredient. It also says it lacks important information on whether PEG-MGF would cause harm in humans [5]. A 2026 clinical review points to uncertainty about the composition of products in unregulated supply chains [3].
The two products have similar names but different molecules: PEGylation increases molecular mass [4], so a certificate of analysis for one can’t stand in for the other. Check that the report names the exact product and gives a mass consistent with it. We price them separately for the same reason, on the MGF price page and the PEG-MGF price page.
Our guides explain how to read a peptide COA, how to check a peptide vendor and what “research use only” means.
More on each
We haven’t published full overviews of these two compounds yet. The MGF page and the PEG-MGF page carry the cited legal status in each market and the latest prices.
Frequently asked questions
What is the difference between MGF and PEG-MGF?
PEG-MGF is marketed as MGF with polyethylene glycol (PEG) chains attached. PEGylation makes a peptide larger and shields it from enzymes, which changes how the body handles it, so results for MGF can't be assumed to apply to PEG-MGF.
Is MGF the same as IGF-1?
No. MGF corresponds to one splice variant of the IGF1 gene, often called IGF-1Ec. Much of the research on MGF used that isoform or synthetic peptides based on its E-domain, not mature IGF-1.
Has PEG-MGF been tested in humans?
A 2026 review found no peer-reviewed human studies of PEG-MGF, and FDA has not identified any human exposure data for products containing it.
Are MGF and PEG-MGF allowed in sport?
No. WADA's 2026 Prohibited List bans mechano growth factors at all times.