Recovery & Repair · IGF-1Ec splice variant · Compounded 503A
MGF: the splice variant your muscle releases after loading.
Mechano Growth Factor (MGF) is a splice variant of the IGF-1 gene — formally IGF-1Ec — expressed by skeletal muscle in response to mechanical loading and damage. It is short-acting and locally active. The PEGylated form (PEG-MGF) extends half-life for systemic dosing; native MGF is studied for short-pulse local repair.
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What Mechano Growth Factor (MGF) is
MGF is the muscle-derived splice variant of the IGF-1 gene, generated by alternative splicing of the IGF-1 transcript after mechanical loading or damage. The mature peptide includes a unique C-terminal E-domain that gives it activity distinct from systemic IGF-1.
Native MGF is short-acting — biologically it is meant to fire briefly in response to loading. The PEGylated form (PEG-MGF) extends its half-life for systemic use; this entry describes native (non-PEGylated) MGF.
It is investigational. It is not FDA-approved. U.S. use is off-label, compounded by licensed 503A pharmacies under physician prescription.
How it works
After mechanical loading or muscle damage, alternative splicing of the IGF-1 gene generates MGF (IGF-1Ec). The C-terminal E-domain activates satellite cells — the resident muscle stem cells responsible for repair and hypertrophy.
A key feature: MGF’s E-domain appears to signal through pathways at least partly independent of the classical IGF-1 receptor, which is why it functions as a distinct repair signal rather than a duplicate of systemic IGF-1.
Its short half-life suits localized pulsed dosing immediately after training or injury, matching the natural release pattern.
What patients use it for
Satellite cell activation
MGF’s defining biological role — recruiting muscle stem cells into the repair cycle.
Localized muscle repair
Pulsed local injection mimics endogenous release after loading.
Short pulse, low systemic exposure
Short half-life keeps systemic IGF-1 elevation minimal — important for cancer screening considerations.
Evidence summary
Goldspink G and colleagues characterized MGF as the mechanically-induced IGF-1 splice variant in the 1990s and 2000s.
Rodent studies show direct effect on satellite cell proliferation and muscle regeneration after injury.
Human clinical trial data is limited; most efficacy claims rest on mechanism and animal models.
Dosing and clinical context
General clinical context only. Kindr Health physicians determine the appropriate dose and protocol for each patient based on history and labs. This is not a prescription or dosing recommendation.
No FDA-approved human dosing exists. Compounded protocols typically use low-microgram subcutaneous dosing immediately post-exercise or at a target injury site.
Native (non-PEGylated) MGF is often dosed every 24–48 hours during a focused recovery cycle.
A kindr physician determines whether a trial is appropriate.
Safety and contraindications
IGF-pathway analogs require pre-treatment IGF-1 labs and active-cancer screening.
Lower systemic IGF-1 exposure than IGF-1 LR3 but the same screening principles apply.
Not for use in pregnancy, breastfeeding, or active malignancy.
Who it's typically considered for
- Adults with focal muscle injury or aggressive training cycles seeking pulsed repair support
- Patients with clean cancer screening and normal-to-low IGF-1
- Patients who prefer a short-pulse, lower-systemic-exposure IGF-axis option over IGF-1 LR3
Frequently asked questions
MGF vs PEG-MGF?
MGF is the native short-acting form; PEG-MGF is PEGylated for an extended half-life and systemic dosing. Both target satellite cell activation.
MGF vs IGF-1 LR3?
MGF specifically activates satellite cells through its E-domain. LR3 is a long-acting systemic IGF-1 analog acting through the classical IGF-1R.
Is it FDA-approved?
No. Compounded for off-label use under physician prescription.
How fast does it work?
Effects on satellite cell recruitment build over a focused recovery cycle (1–4 weeks).
Is it safe?
Within appropriately screened patients and physician supervision, the short-pulse profile is favorable. Cancer history is a contraindication.
Sources
- Yang S et al. Cloning and characterization of an IGF-1 isoform expressed in skeletal muscle subjected to stretch (MGF / IGF-1Ec). J Muscle Res Cell Motil (1996). — pubmed.ncbi.nlm.nih.gov/8923674
- Hill M, Goldspink G. Expression and splicing of the insulin-like growth factor gene in rodent muscle is associated with muscle satellite (stem) cell activation. J Physiol (2003). — pubmed.ncbi.nlm.nih.gov/12626671
- Mills P et al. A synthetic mechano growth factor E peptide enhances myogenic precursor cell transplantation success. Am J Transplant (2007). — pubmed.ncbi.nlm.nih.gov/17511671
Considering Mechano Growth Factor (MGF)?
A Kindr Health physician reviews every longevity intake — peptides are prescribed only when medically indicated based on your history and labs. There is no charge for the initial review.
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Medically reviewed by Kindr Health Clinical Team
Kindr Health Inc. — Editorial & Clinical Team (physician-supervised)
NPI 1609792902 · Last reviewed: July 3, 2026
Last reviewed July 3, 2026. Compounded medications are prepared by FDA-registered 503A pharmacies and are not FDA-approved drug products. Prescriptions require a clinical evaluation; a Kindr Health physician determines eligibility. Not for use in pregnancy. This page provides educational information and is not medical advice.