PEG-MGF
From PeptidePlaza, the free peptide reference · Entry #043 · Recovery · Hand-curated entry · Editorial standards
PEG-MGF (also known as MGF, Mechano Growth Factor, IGF-1Ec, PEG-MGF) is a recovery research peptide. The splice variant of IGF-1 that muscle produces after mechanical damage. Its job is to wake up satellite cells — PEGylation extends a half-life measured in minutes.
Mechano Growth Factor is the IGF-1Ec splice variant, produced locally in skeletal muscle in response to mechanical overload or damage. Alternative splicing of the IGF-1 gene generates a unique C-terminal E-domain peptide; the 24-amino-acid E-domain fragment, which acts independently of the IGF-1 receptor, is what is sold as "MGF". Its documented role is in the earliest phase of muscle repair: activating satellite cells, promoting their proliferation and delaying their differentiation so the pool expands before fusing into damaged fibres. Native MGF is cleared within minutes, so the commercially available form is PEGylated — polyethylene glycol conjugation reduces renal clearance and proteolysis, extending the half-life to a reported 2–3 days. The mechanistic literature on MGF in muscle regeneration is solid; what does not exist is human clinical trial evidence for administered MGF or PEG-MGF as a therapeutic. It is prohibited by WADA as a growth factor and is routinely screened for in sports drug testing. PEGylation itself carries under-discussed concerns: anti-PEG antibodies are increasingly documented, and long-term tissue accumulation of PEG conjugates is not characterised for research-grade material.
1 Mechanism of action
The IGF-1Ec E-domain peptide acts through an IGF-1R-independent pathway to activate quiescent satellite cells, drive their proliferation and delay myogenic differentiation, expanding the progenitor pool available for fibre repair. Also reported to have anti-apoptotic and neuroprotective effects in preclinical models. PEGylation extends circulation time without altering the receptor pharmacology.
Primary targets: IGF-1R-independent E-domain pathway (receptor not definitively identified)
2 Reported effects
Effects below are those reported in the published literature cited on this page. They are not claims of clinical benefit and not medical advice.
2.1 Reported benefits
- Activates satellite cells and expands the muscle progenitor pool in preclinical models
- Targets the earliest phase of muscle repair, distinct from IGF-1's anabolic signalling
- PEGylation extends half-life from minutes to a reported 2–3 days
- Anti-apoptotic and neuroprotective effects reported in animal models
- Investigated in cardiac and neural repair models beyond skeletal muscle
2.2 Side effects
- No human trial safety data
- Injection site reactions and localised swelling
- Anti-PEG antibody formation with repeated exposure
- Theoretical hypoglycaemia from IGF-family cross-reactivity at high doses
- Unknown tissue accumulation of PEG conjugates
- Theoretical tumour promotion via growth factor signalling
3 Chemical and physical properties
| Molar mass | ~2,888 g/mol (unPEGylated peptide) |
|---|---|
| Purity (typical) | >98% |
| Half-life | Native MGF: minutes. PEGylated form: reported 2–3 days |
| Storage | −20 °C, lyophilised powder, desiccated |
| Solubility | Sterile water / bacteriostatic water |
| Receptors / targets | IGF-1R-independent E-domain pathway (receptor not definitively identified) |
3.1 Amino acid sequence
Tyr-Gln-Pro-Pro-Ser-Thr-Asn-Lys-Asn-Thr-Lys-Ser-Gln-Arg-Arg-Lys-Gly-Ser-Thr-Phe-Glu-Glu-Arg-Lys (IGF-1Ec E-domain, PEG-conjugated)
4 Research dosages
No validated protocol. Research conventions cite 200–400 μg two to three times weekly for the PEGylated form, extrapolated from animal data rather than clinical evidence.
5 Research studies (7)
- Mechano-Growth Factor E-Domain Peptide Enhances Satellite Cell Proliferation
Journal of Physiology (2003) · Preclinical · N/A (cell and animal models)Foundational work characterising the IGF-1Ec splice variant response to mechanical loading and its distinct action on muscle precursor cells.Key finding: The MGF E-domain acts independently of mature IGF-1 to activate satellite cells and delay their differentiation. - The role of mechano growth factor in chondrocytes and cartilage defects: a concise review.
Acta biochimica et biophysica Sinica (2023) · ReviewMechano growth factor (MGF), an isoform of insulin-like growth factor 1 (IGF-1), is recognized as a typical mechanically sensitive growth factor and has been shown to play an indispensable role in the skeletal... - Mechano-growth factor E-domain modulates cardiac contractile function through 14-3-3 protein interactomes.
Frontiers in physiology (2022) · PreclinicalIn the heart, alternative splicing of the igf-I gene produces two isoforms: IGF-IEa and IGF-IEc, (Mechano-growth factor, MGF). - Mechano growth factor interacts with nucleolin to protect against cisplatin-induced neurotoxicity.
Experimental neurology (2020) · PreclinicalMechano growth factor (MGF) is an alternatively spliced form of insulin-like growth factor-1 (IGF-1) that has shown to be neuroprotective against 6-hydroxydopamine toxicity and ischemic injury in the brain. - Immunohistochemical expression of insulin-like growth factor-1Ec in primary endometrial carcinoma: Association with PTEN, p53 and survivin expression.
Oncology letters (2020) · PreclinicalChronic hyperinsulinemia due to insulin resistance and elevated levels of insulin-like growth factor (IGF)-1 and IGF-2 are suggestive of a significantly higher risk of endometrial carcinoma. - Mechano growth factor, a splice variant of IGF-1, promotes neurogenesis in the aging mouse brain.
Molecular brain (2017) · PreclinicalMechano growth factor (MGF) is a splice variant of IGF-1 first described in skeletal muscle. - Mechano-growth factor E peptide promotes healing of rat injured tendon.
Biotechnology letters (2016) · PreclinicalMGF-C25E plays an important role in promoting healing of injured rat tendon and could be used as a potential therapeutic factor for tendon repair.
6 Safety and risk profile
6.1 Regulatory status
PEG-MGF is currently classified as Not approved. It has no approved human indication in the United States; availability elsewhere does not imply demonstrated safety or efficacy.
Safety score: 45/100 — moderate concern. Derived from clinical data volume, known risks and regulatory status.
6.2 Contraindications
Conditions and populations in which use is contraindicated:
- Known or suspected malignancy
- Active proliferative retinopathy
- Pregnancy or lactation
- Known hypersensitivity to PEGylated products
6.3 Drug interactions
| Drug or class | Interaction | Risk |
|---|---|---|
| IGF-1 / IGF-1 LR3 | Overlapping growth factor signalling with additive hypoglycaemia and proliferative risk. | High |
| Insulin | Potential additive glucose lowering via IGF-family receptor cross-talk. | Moderate |
| Growth hormone secretagogues | Complementary anabolic pathways; entirely uncharacterised in combination. | Moderate |
6.4 Long-term risks
- Anti-PEG antibody development reducing efficacy and risking hypersensitivity
- Unknown consequences of repeated growth factor stimulation of satellite cells
- Theoretical malignancy risk from chronic growth factor exposure
- No data on PEG tissue accumulation from long-term use
6.5 Research best practices
- Store lyophilised at −20 °C; protect from light
- Reconstitute gently — do not shake, as PEGylated peptides are shear-sensitive
- Avoid freeze-thaw cycles entirely
- Verify PEGylation by mass spec; unPEGylated material has drastically different kinetics
7 Frequently asked questions
- How is MGF different from IGF-1?
- Same gene, different splice product. Mature IGF-1 signals through the IGF-1 receptor to drive systemic anabolism; the MGF E-domain peptide acts through a separate, still incompletely identified pathway and is specialised for the early satellite-cell activation phase of muscle repair.
- Why is it PEGylated?
- Native MGF is cleared in minutes, which makes practical dosing impossible. Attaching polyethylene glycol increases hydrodynamic size, reducing renal filtration and proteolytic attack, and stretches the reported half-life to days.
- Is there human evidence it works?
- No. The mechanistic and animal literature on MGF in muscle regeneration is real, but no controlled human trial has evaluated administered MGF or PEG-MGF for muscle growth or recovery. It is banned by WADA and screened in doping tests.
8 References
- The role of mechano growth factor in chondrocytes and cartilage defects: a concise review. PubMed (2023). Liu Y, et al.. View source
- Mechano-growth factor E-domain modulates cardiac contractile function through 14-3-3 protein interactomes. PubMed (2022). Solís C, et al.. View source
- Mechano growth factor interacts with nucleolin to protect against cisplatin-induced neurotoxicity. PubMed (2020). Podratz JL, et al.. View source
- Immunohistochemical expression of insulin-like growth factor-1Ec in primary endometrial carcinoma: Association with PTEN, p53 and survivin expression. PubMed (2020). Stavropoulos A, et al.. View source
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