Healing · Cardiovascular · Ophthalmic
TB-500 (Thymosin Beta-4)
Also known as: Thymosin Beta-4, Tβ4, TB4, RGN-352 (acetate fragment)
A naturally occurring 43-amino-acid actin-sequestering peptide investigated for wound healing, dry eye, and cardiac repair, with mixed Phase 2 readouts and no FDA approval.
Sign in to add to watchlistEvidence strength
Strength of human clinical evidence — A (strongest) to D (mostly preclinical). This reflects research maturity, not safety or suitability.
Vial Theory provides educational research summaries only. Content is not medical advice, diagnosis, treatment, dosing guidance, or individualized suitability screening. Regulatory status can change over time and varies by jurisdiction.
Key Takeaways
- ›Thymosin beta-4 (marketed as 'TB-500') is a natural cell-repair peptide that regulates the actin cytoskeleton.
- ›Phase 2 trials in eye and wound conditions were mixed; there is no FDA approval.
- ›'TB-500' is used inconsistently and online/veterinary products may not match the trial molecule.
- ›It is on the WADA prohibited list, and a theoretical cancer-biology concern is unresolved.
- ›Athletic-recovery claims exceed the evidence. Speak with a licensed healthcare professional.
What It Is
Thymosin beta-4 is a naturally occurring 43-amino-acid peptide first isolated from thymic tissue and now known to be the principal G-actin-sequestering peptide in most mammalian cells. It is highly conserved across species and present at high intracellular concentrations, where it regulates the actin cytoskeleton by binding monomeric G-actin and preventing its polymerization into F-actin filaments.
The terms 'thymosin beta-4' and 'TB-500' are used inconsistently in the literature and online discussion. RegeneRx Biopharmaceuticals developed the synthetic full-length peptide under research designations including RGN-259 (ophthalmic) and RGN-352 (systemic), and pursued indications in dry eye disease, neurotrophic keratopathy, venous stasis ulcers, and cardiac repair. 'TB-500' is sometimes used to refer to the same full-length molecule and sometimes to a smaller bioactive fragment, which is a relevant ambiguity when interpreting online claims.
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Disclaimer: This content is for educational and research purposes only and is not medical advice. Always consult a licensed healthcare professional before making health-related decisions.