Thymosin Beta-4 (TB-500) — Wound Healing Peptide — Immunity
44-amino-acid peptide involved in tissue repair, wound healing, and anti-inflammation. Research compound, not FDA-approved.
Overview
Thymosin beta-4 (TB-4) is a 43-amino-acid peptide that is the most abundant member of the beta-thymosin family and one of the most abundant intracellular peptides in mammalian cells. It plays a central role in actin polymerization dynamics, sequestering G-actin monomers to regulate cytoskeletal organization — a process critical for cell migration, wound healing, and tissue repair. Beyond its cytoskeletal role, thymosin beta-4 has demonstrated anti-inflammatory, anti-fibrotic, and cytoprotective properties in numerous preclinical models. In rodent studies, TB-4 accelerated dermal wound healing, promoted cardiac repair after myocardial infarction, reduced corneal inflammation, and facilitated hair follicle stem cell migration. TB-500 is a synthetic fragment or analog of thymosin beta-4 used in veterinary medicine (equine) and in the research/bodybuilding community. RegeneRx Biopharmaceuticals developed RGN-259 (a sterile TB-4 ophthalmic solution) that completed Phase 3 trials for neurotrophic keratitis (persistent corneal epithelial defect). Clinical data for systemic use in humans are limited. Thymosin beta-4 is available from compounding pharmacies and peptide research suppliers, and is used in functional medicine for soft tissue injury recovery, chronic inflammation, and general tissue repair. It was banned by WADA in 2010.
Indications
- Investigational: Corneal wound healing (RGN-259 — Phase 3 for neurotrophic keratitis)
- Investigational: Cardiac repair post-MI (preclinical)
- Veterinary: Equine soft tissue injury
- Unapproved: Soft tissue injury recovery, wound healing (anti-aging/functional medicine)
Mechanism of Action
TB-4 sequesters G-actin monomers, regulating actin polymerization dynamics critical for cell migration, adhesion, and wound closure
Dosing
| Compound | Dose | Frequency | Notes |
|---|---|---|---|
| Thymosin Beta-4 (TB-500) | 2.5 mg | Twice weekly (loading phase: 4-6 weeks) | Common loading protocol in functional medicine |
| TB-500 | 2.5 mg | Once weekly (maintenance) | Maintenance dose after loading phase |
Evidence Grade
GRADE C
Safety & Contraindications
- Limited human safety data for systemic administration
- Generally well-tolerated in clinical trials (ophthalmic use)
- Injection site reactions
- Theoretical cancer promotion concern (promotes cell migration and angiogenesis — could theoretically support tumor growth)
- Not FDA-approved for systemic use
- WADA prohibited substance (since 2010)
- Research peptide quality varies