Thymosin Beta-4

Last Updated: July 2026

Thymosin Beta-4 (Tβ4) is a ubiquitous, naturally occurring 43-amino-acid peptide — the body's principal G-actin-sequestering molecule, concentrated in platelets, wound fluid, and many tissues. It is the full-length parent of the widely sold TB-500, and the molecule used in most published tissue-repair, wound-healing, and cardiac research. It is not approved and is supplied for research use only.

What is Thymosin Beta-4, and how does it differ from TB-500?

This is the single most important framing for the compound: TB-4 is the complete 43-amino-acid peptide with several functional domains, while "TB-500" most rigorously refers to a shorter synthetic fragment (the Ac-LKKTETQ actin-binding motif, residues 17–23) — they are related but not necessarily the same molecule, and much of the efficacy literature was generated with full-length TB-4. Vendors often use the two names loosely, which is a real source of confusion; if a study you're relying on used full-length TB-4, a fragment labeled "TB-500" may not reproduce it. Note that some suppliers also sell full-length 43-aa material under the "TB-500" name — another reason identity testing matters.

How does Thymosin Beta-4 work?

By binding and sequestering monomeric G-actin, TB-4 maintains a reservoir that cells draw on to rapidly build the actin filaments needed for migration — the basis for its roles in wound healing, angiogenesis, and tissue repair. Full-length TB-4 also carries signaling sequences the isolated fragment lacks, and can be cleaved at its N-terminus to the separately active peptide Ac-SDKP.

What does the research on Thymosin Beta-4 show?

Preclinical studies show TB-4 promotes dermal wound healing and activates cardioprotective (Akt) survival signaling after simulated myocardial infarction, with additional work in corneal and neural repair; human clinical work has reached early-phase (e.g. cardiac and dermal) but there are no large approved outcomes trials. Evidence level: Extensive preclinical + early-phase human; not approved.

What are the safety concerns and regulatory status?

Thymosin Beta-4 is not approved for human use, its long-term human safety is not established, and it is prohibited in sport (WADA). See the legal status guide.

Why does vendor verification matter, and how does Peptigrity verify?

Because "TB-4" and "TB-500" are used interchangeably in the market despite referring to different molecules, mass-spec identity (full-length peptide vs the ~889 Da fragment) and HPLC purity are exactly the checks a buyer needs. Peptigrity buys it anonymously, tests it at independent ISO-accredited labs, and publishes the unedited COA; the trust score weights lab purity and reviews equally (50/50). See how to read lab results.

Educational information only; not medical advice. Thymosin Beta-4 is not approved for human use. Consult a qualified healthcare provider. Peptigrity does not sell, endorse, or recommend products or vendors.