HomePeptides › Thymosin Beta-4

Thymosin Beta-4

TB4, Tbeta4

Tier 3 · Limited Human Data
Class
Actin-sequestering protein
Molecular target
G-actin
Sequence / structure
43-aa acidic polypeptide
Evidence tier
Tier 3 — Limited Human Data
Category
Tissue Repair & Cytoprotection

Biology & mechanism

The full-length molecule, and the one the actual research concerns — a distinction routinely blurred by vendors selling “TB-500”. It is among the most abundant proteins in most cells, binding monomeric G-actin and regulating the polymerisation that drives cell migration. Its effects on angiogenesis, keratinocyte migration and inflammation follow from that role.

What the research actually shows

Reached genuine clinical trials — phase 2 in dry eye disease, venous stasis ulcers and epidermolysis bullosa — which is more than TB-500 can claim. Results were insufficient to carry it to approval. Extensive preclinical work in cardiac and corneal repair.

Regulatory status

Not FDA-approved. Development discontinued. Prohibited in sport (WADA S0).

Safety signals

Trial safety data exist at studied exposures. The pro-angiogenic mechanism carries the same unresolved theoretical concern as BPC-157 — an agent that promotes vessel growth does not choose which tissue benefits.

No usage guidance is published here

Forge Bioenergy does not publish dosing, reconstitution, or administration protocols for any peptide. See our editorial policy for why. If you are considering any substance on this page, that conversation belongs with a licensed physician.

References & further reading

Regulatory status changes. This page reflects our reading of public sources as of July 2026 and should be independently verified before it is relied upon.

Important notice Forge Bioenergy publishes scientific reference information only. Nothing on this site is medical advice, a therapeutic claim, or a recommendation to use any substance in humans. Many peptides described here are not approved by the FDA for any use, and several are approved only for narrow indications under prescription. We do not publish dosing, administration, or usage protocols. Consult a licensed physician before making any medical decision.