Side-by-side · Research reference
LL-37vsMGF
Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.
AHuman-MechanisticHUMAN-REVIEWED15/35 cited
BAnimal-StrongHUMAN-REVIEWED14/55 cited
LL-37
Cathelicidin · Human AMP
Broad-spectrumAntimicrobial activity
Endogenous · Secreted at inflammation sites
MGF
IGF-1Ec Splice Variant · Muscle-Specific
SQ · Research context only
01Mechanism of Action
Parameter
LL-37
MGF
Primary target
Satellite cells (Pax7+) in skeletal muscleMoore 2018
Pathway
hCAP-18 precursor → Proteinase-3 cleavage → LL-37 release → Membrane insertion/disruption
Mechanical stress → IGF-1Ec mRNA upregulation → Local E-domain peptide release → Satellite cell activation
Downstream effect
Membrane permeabilization, cytokine induction, autophagy, phagosome-lysosome fusion, chemotaxisAhmad 2026Zhang 2026
Satellite cell proliferation, myoblast differentiation, muscle fiber repair
Feedback intact?
—
—
Origin
Endogenous human cathelicidin (37-AA fragment, residues 134–170 of hCAP-18)
Alternative splicing of IGF-1 gene (exons 4-6) produces IGF-1Ec precursor; E-domain cleaved post-translationallyArmakolas 2016Vassilakos 2017
Antibody development
—
—
02Dosage Protocols
Parameter
LL-37
MGF
Endogenous expression
Constitutive in neutrophils, epithelial tissues
Upregulated during infection and inflammation.Pinheiro 2026
—
Exogenous (experimental)
Dose varies by study; antimalarial ~10–50 μM in vitro
No FDA-approved exogenous formulation.
—
Plasma levels (malaria)
Elevated in infected patients and miceHe 2026
Exogenous administration reduced parasitemia in murine models.He 2026
—
Evidence basis
In vitro, animal models, human observational
Animal models + in vitro only
Synthetic peptide
—
24-amino-acid E-domain sequence
Corresponds to human IGF-1Ec exons 4-6 region.
Rodent cardiac model
—
200 μg/kg via peptide-eluting microstructures
Post-MI injection; improved ejection fraction by 8 weeks.
Acute delivery (mouse MI)
—
Single bolus within 12 hrs post-infarctionShioura 2014
Delayed decompensation; no human protocol established.
Human evidence
—
None — no published clinical trials
All dosing extrapolated from animal models.
Detection in doping
—
Full-length MGF detected via LC-MS in illicit productsThevis 2014
WADA-prohibited since 2005; no therapeutic indication.
04Side Effects & Safety
Parameter
LL-37
MGF
Cytotoxicity (high dose)
Membrane disruption in host cells at supraphysiological concentrations
—
Pro-inflammatory signaling
Can exacerbate inflammation in certain contexts (context-dependent)Pinheiro 2026
—
Theoretical cancer risk
Immunomodulatory roles in tumor microenvironment under investigation
—
Human safety data
—
None — no clinical trials published
Theoretical IGF-1 axis risk
—
Chronic IGF-1Ec overexpression linked to cancer progression (prostate, colorectal, breast)
Tumor promotion
—
IGF-1Ec overexpressed in osteosarcoma, colorectal polyps with dysplasia, endometrial cancer
Antibody development
—
Unknown — no longitudinal human exposure data
Local injection reaction
—
Presumed similar to other peptides (erythema, induration) — no direct evidence
Dysregulated expression with age
—
Older adults (70+ yrs) show blunted IGF-1Ec response post-exercise vs youngMoore 2018
Absolute Contraindications
LL-37
—MGF
- ·Active malignancy or history of IGF-1-sensitive cancers (prostate, colorectal, breast, osteosarcoma)
- ·No established therapeutic use — investigational only
Relative Contraindications
LL-37
- ·Active autoimmune disease (theoretical immune dysregulation)
MGF
- ·Family history of IGF-1-axis malignancies
- ·Use outside research setting
05Administration Protocol
Parameter
LL-37
MGF
1. Natural secretion
LL-37 is constitutively expressed in neutrophils and epithelial cells, cleaved from hCAP-18 by proteinase-3 at sites of infection or inflammation.
MGF (E-domain peptide) has no approved clinical protocol. All published data derive from animal models or in vitro experiments.
2. Experimental formulations
Synthetic LL-37 and derivatives (e.g., SAMP-12aa) tested in vitro and animal models. Administered via topical, intraperitoneal, or intravenous routes in research settings.
Commercially available MGF corresponds to the 24-amino-acid human E-domain (hEc). Rodent E-domain (Eb) is structurally distinct and not interchangeable.
3. Stability considerations
LL-37 is resistant to pepsin degradation at gastric pH. Synthetic short peptides designed to retain this stability while reducing toxicity.Lu 2026
Rodent studies used peptide-eluting polymeric microstructures (cardiac) or direct intramuscular injection. Routes and doses non-translatable to humans.Peña 2015Shioura 2014
4. WADA prohibition
—
MGF peptides prohibited in sport since 2005. Detection via LC-MS established for full-length MGF products.Thevis 2014
5. Research context only
—
Any human use falls outside approved medical practice and regulatory frameworks. No safety or efficacy data exist.
06Stack Synergy
LL-37
— no documented stacks
MGF
+ BPC-157
Multi-pathwayMGF activates satellite cells for muscle fiber repair; BPC-157 promotes angiogenesis, collagen synthesis, and tendon healing via distinct pathways (VEGF, FAK, integrin signaling). Theoretical synergy in post-injury contexts combines myogenic (MGF) and stromal (BPC-157) repair mechanisms. Both lack human validation.
- MGF
- No established dose
- BPC-157
- 250–500 mcg SQ near injury site
- Context
- Animal models only
- Primary benefit
- Theoretical multi-tissue repair (muscle + tendon/ligament)
+ TB-500
ModerateTB-500 (thymosin beta-4 fragment) enhances actin polymerization, cell migration, and angiogenesis—complementary to MGF satellite cell activation. Both upregulated post-injury; combined use presumed additive for muscle regeneration in preclinical models.
- MGF
- No established dose
- TB-500
- 2–5 mg SQ weekly
- Context
- Animal models only
- Primary benefit
- Satellite cell activation + enhanced migration/angiogenesis