MGF

MGF (mechano growth factor) is a synthetic peptide based on a splice variant of IGF-1 that muscles briefly produce in response to mechanical stress and injury, and it's linked to activating the muscle stem cells that repair and rebuild tissue after that stress. It's pursued for muscle growth and repair on the strength of that biology. It's not FDA-approved for any use, human efficacy trials of the injectable peptide don't exist, and it's banned in drug-tested sport. Some researchers also question whether a natural MGF peptide has ever actually been isolated from animal tissue.

MGF (mechano growth factor), a splice variant of IGF-1, has been studied for muscle growth and repair, and the evidence is almost entirely preclinical. Foundational work in rabbits showed mechanical loading upregulates MGF in muscle, and mouse studies reported it protects motor neurons in an ALS model and increases neurogenesis in the aging brain. Importantly, a detailed review cautions that no natural MGF peptide has been isolated from animal tissue — the effects described come from a synthetically made peptide, and how well they translate to humans is unresolved. There are no human clinical trials of the injectable MGF peptide.

Not FDA-approved for any indication. Investigational / research-supply only. MGF is a synthetic peptide corresponding to the C-terminal region of the IGF-1Ec splice variant; there is no approved MGF product in any jurisdiction. WADA status: prohibited at all times. "Mechano growth factors (MGFs)" are explicitly named on the WADA 2026 Prohibited List under S2.3 (Growth Factors and Growth Factor Modulators), alongside IGF-1 (mecasermin) and its analogues. Not DEA-scheduled.

MGF is not FDA-approved, and there are no human trials establishing its safety or effectiveness. Because it is a growth-factor peptide, it is prohibited in regulated sport at all times — "mechano growth factors (MGFs)" are named directly on the WADA 2026 Prohibited List under S2.3 (growth factors and growth factor modulators), alongside IGF-1 and its analogues. A general concern for any IGF-1-related growth factor is that promoting cell growth could be undesirable in the presence of undiagnosed cancer, though this is theoretical for MGF specifically. VialWise is a research and educational reference, not medical advice.

⚠️ For research and educational purposes only. MGF (mechano growth factor) is not approved by the FDA for any indication. It is a research-supply peptide with no human efficacy trials. Information in this entry is informational, not medical advice. Always confirm dose calculations with the in-app calculator and consult appropriate professional guidance before any protocol decisions.

⚠️ The evidence is preclinical, and the "synthetic MGF" caveat is central. Almost all MGF data comes from cell and animal studies. A key review of the field emphasizes that no endogenous MGF peptide has ever been isolated from tissue or body fluid — the biological effects attributed to "MGF" come from a synthetically manufactured peptide corresponding to the C-terminal residues of the IGF-1Ec splice variant.[²] Whether that synthetic peptide reproduces a real physiological signal in humans is unresolved. Read the mechanisms and effects below with that limitation in mind.

⚠️ Prohibited in sport at all times (WADA S2.3). "Mechano growth factors (MGFs)" are named by name on the WADA 2026 Prohibited List under S2.3 (Growth Factors and Growth Factor Modulators), alongside IGF-1 (mecasermin) and its analogues — prohibited at all times, in and out of competition, as a non-Specified Substance. Researchers in regulated sport should verify current status with their anti-doping organization.

MGF (mechano growth factor) is a synthetic peptide based on a naturally occurring splice variant of insulin-like growth factor 1 (IGF-1). The IGF-1 gene can be alternatively spliced into more than one isoform. One isoform (often called IGF-1Ea) resembles the main circulating, liver-derived IGF-1 and acts in an endocrine (hormone-like) fashion. A second isoform — IGF-1Ec in humans, IGF-1Eb in rodents — carries a different C-terminal exon sequence and is associated with a local, autocrine/paracrine action. This second form was named "mechano growth factor" because its expression is upregulated by mechanical stress.[¹][²]

Foundational finding. In a foundational rabbit study, mechanical stretch (via cast immobilization) and stretch combined with electrical stimulation markedly upregulated both IGF-1 isoforms in skeletal muscle, whereas electrical stimulation *without* stretch did not — establishing that the MGF splice event is a response to mechanical loading and tissue remodeling, not merely muscle activity.[¹] The concept that followed: after loading or injury, muscle briefly produces the MGF isoform, which is linked to activating satellite cells (muscle stem cells) that drive repair and growth.

The synthetic-vs-endogenous caveat. An authoritative minireview reviewed the field and made an important point that is easy to lose in marketing copy: a synthetically manufactured peptide corresponding to the 24 most C-terminal residues of IGF-1Eb has been shown to promote cell proliferation and survival in the lab — but no analogous peptide product of the IGF-1 gene has been isolated from cultured cells, their medium, or animal tissues or fluids.[²] In other words, the "MGF peptide" that research suppliers sell is a laboratory construct whose status as a real, circulating physiological molecule is unproven. This distinguishes MGF from peptides where the injected molecule matches a well-characterized natural hormone.

Mechanism (as described in preclinical work). Beyond muscle, synthetic MGF has been studied for neuroprotection and neurogenesis. In the SOD1(G93A) mouse model of ALS, delivery of an MGF-encoding plasmid to hindlimb muscle improved muscle strength and increased motor-unit and motoneuron survival, with *more* motoneurons surviving than with standard IGF-1.[³] In the aging mouse brain, MGF overexpression increased proliferating cells and mature neurons in neurogenic zones and was associated with preserved olfactory function, suggesting a role in adult neurogenesis.[⁴] A study of growth-plate cartilage found MGF is expressed there but that adding MGF peptide did not increase chondrocyte proliferation — a useful counterweight showing MGF's proliferative effect is not universal across tissues.[⁵]

Evidence quality. The MGF evidence base is preclinical — rabbits, mice, and cell culture. There are no human clinical trials of the injectable synthetic MGF peptide. The muscle-repair and neuroprotection signals are biologically interesting but have not been tested in people, and the synthetic-vs-endogenous question above adds a layer of uncertainty specific to this compound.

Regulatory status (US). MGF is not FDA-approved for any indication and is not DEA-scheduled. It is available only as a research-supply peptide outside the FDA-recognized supply chain.

Regulatory status (sport — WADA). MGF is prohibited at all times. It is not merely captured by a general category: the 2026 Prohibited List names "Mechano growth factors (MGFs)" explicitly under S2.3 (Growth Factors and Growth Factor Modulators), in the same bulleted list as IGF-1 (mecasermin) and its analogues, VEGF, PDGF, HGF, FGFs, and thymosin-β4/TB-500. Verify current status directly via the WADA Prohibited List and your National Anti-Doping Organization.

Common research interests. MGF is discussed in the research community for muscle repair and hypertrophy (satellite-cell activation), post-injury recovery, and — from the animal literature — neuroprotection and neurogenesis. These interests are extrapolated from preclinical data and are not established human uses.

Commonly reported

• Injection-site reactions (redness, soreness, swelling)
• Non-specific reactions to research-supply material of variable purity
• Growth-promoting signaling. IGF-1 and related growth factors promote cell proliferation. The theoretical concern for any IGF-1-family compound is that this could be undesirable in the presence of undiagnosed malignancy. This is a class-level caution, not an MGF-specific finding.
• Hypoglycemia. IGF-1 itself can lower blood glucose; whether the MGF peptide shares this is not characterized, but it is a reason for caution given the family.
• Unknown long-term effects. No long-term human data of any kind exist.

Pregnancy and lactation — no data; default to contraindicated

Pediatric use — no data; should not be used in researchers under 18

Active or history of malignancy — caution; growth-factor signaling in the cancer context is a recognized theoretical concern for the IGF-1 family

Known hypersensitivity to the peptide — contraindicated

Regulatory note (US): MGF is not FDA-approved and is available only as a research-supply peptide outside the FDA-recognized supply chain.

Regulatory note (sport): MGF is prohibited at all times — named explicitly on the WADA 2026 Prohibited List under S2.3 (growth factors and growth factor modulators). Verify with your anti-doping organization before use.

Not DEA-scheduled.

IGF-1 (insulin-like growth factor 1)

A hormone that mediates many of growth hormone's effects and helps drive tissue growth and repair. MGF is one of the alternatively spliced forms of the IGF-1 gene.

Splice variant

The same gene can be read in different ways to make slightly different proteins. MGF is one splice variant of IGF-1, distinguished by a different tail sequence.

Satellite cells

Muscle stem cells that sit alongside muscle fibers and are activated to repair and grow muscle after exercise or injury. MGF is studied for its role in activating them.

Preclinical

Research done in cells or animals, before any human testing. Preclinical results often do not carry over to people.

Half-life

How long it takes for half of a substance to clear from the blood. MGF is reported to have a very short half-life.

1. McKoy G, Ashley W, Mander J, Yang SY, Williams N, Russell B, Goldspink G. (1999). Expression of insulin growth factor-1 splice variants and structural genes in rabbit skeletal muscle induced by stretch and stimulation. The Journal of Physiology, 516(Pt 2):583–592.(PMID 10087355)
2. Matheny RW Jr, Nindl BC, Adamo ML. (2010). Minireview: Mechano-growth factor: a putative product of igf-I gene expression involved in tissue repair and regeneration. Endocrinology, 151(3):865–875.(PMID 20130113)
3. Riddoch-Contreras J, Yang SY, Dick JRT, Goldspink G, Orrell RW, Greensmith L. (2008). Mechano-growth factor, an igf-I splice variant, rescues motoneurons and improves muscle function in SOD1(G93A) mice. Experimental Neurology, 215(2):281–289.(PMID 19038252)
4. Tang JJ, Podratz JL, Lange M, Scrable HJ, Jang MH, Windebank AJ. (2017). Mechano growth factor, a splice variant of IGF-1, promotes neurogenesis in the aging mouse brain. Molecular Brain, 10(1):23.(PMID 28683812)
5. Schlegel W, Raimann A, Halbauer D, Scharmer D, Sagmeister S, Wessner B, Helmreich M, Haeusler G, Egerbacher M. (2013). Insulin-like growth factor I (IGF-1) Ec/Mechano Growth factor — a splice variant of IGF-1 within the growth plate. PLoS One, 8(10):e76133.(PMID 24146828)

• IGF-1 LR3 — discussed together in this entry's stacks section
• BPC-157 / TB-500 Blend — discussed together in this entry's stacks section
• AOD-9604 — same mechanism class
• HGH (Human Growth Hormone) / Somatropin — same mechanism class
• ACE-031 — shared research area
• AICAR — shared research area