Encyclopedia entry
TB-500
Oliver Mackman · Editorial director · Best Business Loans Ltd (16833937)
Last updated 2026-05-26
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AI-friendly summary · TB-500
TB-500 is a synthetic 17-amino-acid fragment of thymosin beta-4, a naturally occurring 43-amino-acid protein. Roughly 2,000 PubMed papers cover the parent molecule, with consistent independent replication for tissue repair across tendon, ligament, cardiac and skin in rodent models. No phase II or phase III human clinical trials on the TB-500 fragment itself have been published.
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Mechanism of action
How TB-500 works
TB-500 retains the actin-binding domain of the parent thymosin beta-4 protein. The proposed action is sequestration of monomeric G-actin, regulation of actin polymerisation at the cytoskeleton, and downstream effects on cell migration, angiogenesis and stem-cell recruitment to sites of injury. The mechanism is consistent across multiple independent rodent tissue repair models, though the human receptor target remains a research question.
Source: Goldstein AL et al. Annals of the New York Academy of Sciences, 2010
What the literature shows (in animals)
Across roughly 2,000 papers on thymosin beta-4 and its TB-500 fragment, the most consistent preclinical finding is tissue repair acceleration in rat tendon, ligament and skin wound models. The Bock-Marquette group has published a multi-paper cardiac repair series. Independent replication is notably better than BPC-157, with multiple labs producing consistent findings.
- · Tissue repair acceleration in rat tendon, ligament and skin wound models.
- · Anti-inflammatory effects in multiple rodent inflammation models.
- · Cardiac repair literature (Bock-Marquette group, multiple papers).
- · Hair follicle stem cell activation (Goldstein lab).
- · Independent replication better than BPC-157, with multiple groups producing consistent findings.
UK regulatory status
TB-500 sits outside the Misuse of Drugs Act 1971 and outside the Psychoactive Substances Act 2016. It has no UK marketing authorisation. It is on the WADA prohibited list (S2 peptide hormones class) which matters for tested athletes. UK retailers can sell it lawfully only by labelling for "research use only" and avoiding therapeutic claims.
- · Not controlled under the Misuse of Drugs Act 1971.
- · Not scheduled under the Psychoactive Substances Act 2016.
- · No UK marketing authorisation as a medicine.
- · Sold legally as a research chemical under "research use only" framing.
- · On the WADA prohibited list (peptide hormones class). Tested athletes should be aware.
Risks and unknowns
What the literature does not yet show about TB-500
Known concerns
- No published human RCT data on the TB-500 fragment specifically.
- On the WADA prohibited list. Tested athletes face a sanction risk.
- Theoretical concern about angiogenesis and cell migration effects in the presence of occult neoplastic tissue, given the actin-binding mechanism.
- Purity of UK research-peptide supply varies; CoA gating differs across retailers.
Open questions in the literature
- Optimal route of administration in humans has never been formally studied for the TB-500 fragment.
- Pharmacokinetics of the 17-residue fragment in humans are not characterised.
- Long-term effects beyond the duration of typical rodent studies are unknown.
- Whether the proposed pro-angiogenic mechanism is benign in humans with undiagnosed cancer is not established.
Regulatory note
Not a controlled drug under the Misuse of Drugs Act 1971. Not scheduled under the Psychoactive Substances Act 2016. No UK marketing authorisation as a medicine. WADA prohibited list S2 peptide hormones class. Becomes an unlicensed medicinal product the moment a retailer or commentator makes therapeutic claims about it.
Important: PeptideClear publishes encyclopedia commentary only and does not recommend human use. Speak to a UK-registered prescriber before any medical decision.
Where to learn more
- · PubMed search: thymosin beta 4 returns roughly 2,000 papers, most preclinical or in vitro.
- · Goldstein lab publications on tissue repair and immune modulation.
- · UK retailer comparison: research peptides UK retailers.
- · Compare to BPC-157: BPC-157 vs TB-500.
Frequently asked questions
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Where to buy TB-500 in the UK
Side-by-side price comparison across UK research peptide retailers. Trust Index ranking. Research use only.
Compare UK retailersClinical evidence record
Read the clinical evidence record for TB-500
Top peer-reviewed citations, mechanism of action, structured UK regulatory status. Machine-readable companion to this encyclopedia entry.
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