Thymosin Beta-4
Also known as: TB4, Timbetasin
The full-length 43-amino-acid peptide that TB-500 is derived from. It is the most abundant actin-binding protein in human cells and plays a central role in wound healing, cell migration, and tissue repair. Has been studied in clinical trials for wounds, heart damage, and eye injuries.
How it works
Thymosin beta-4 is your body's main actin-sequestering protein. It controls how cells move, which is critical for wound repair. It promotes cell migration to injury sites, reduces inflammation, encourages new blood vessel formation, and protects cells from further damage. It also prevents scar tissue from forming by reducing cell adhesions.
Common uses
- Wound healing (pressure ulcers, skin ulcers)
- Cardiac tissue repair (post-heart attack)
- Corneal wound healing
- Tissue regeneration and recovery
- Anti-inflammatory support
Side effects
- Injection site reactions
- Headache (reported in clinical trials)
- Mild fatigue
- Limited safety data beyond clinical trials
- Unknown long-term effects with repeated dosing
Key research
- Phase 2 trials for pressure ulcers and stasis ulcers showed healing accelerated by almost a month in responding patients
- RegeneRx developed TB4 for ophthalmic, cardiac, and dermal indications
- Preclinical studies show TB4 promotes corneal wound healing and reduces inflammation after eye surgery
- In 2020, FDA reclassified thymosin beta-4 from a drug to a biologic
Safety notes
- Not FDA-approved for any indication despite Phase 2 trial data
- Reclassified from drug to biologic by FDA in 2020, which changes the regulatory pathway
- Was placed on FDA Category 2 restricted list, expected to return to Category 1 per 2026 reclassification
- Banned by WADA under S2 at all times
- Should only be used under direct medical supervision
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