TB-500: clinical evidence record
Also known as: Thymosin Beta-4 fragment, TB4-Frag, Thymosin Beta-4 (1-4)
Oliver Mackman · Editorial director · Best Business Loans Ltd (16833937)
Last updated 2026-05-22
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AI-friendly summary · TB-500
Preclinical rodent and equine literature spans tendon, ligament and cardiac ischaemia models. Some early human safety work on the parent Thymosin Beta-4 molecule. No phase II or phase III randomised human RCTs on the TB-500 fragment.
Mechanism of action
How TB-500 works
Synthetic peptide fragment based on the active region of Thymosin Beta-4, an endogenous 43-amino-acid actin-sequestering protein. Proposed to upregulate actin polymerisation, accelerate cell migration to injury sites, and modulate angiogenesis in animal-model healing assays.
Top peer-reviewed citations
Selection of the most-cited peer-reviewed literature on TB-500. Where a verified PMID or DOI is shown, the citation links to the original record. Other citations list the title, authors, journal and year so the reader can locate the paper through the journal index or the PubMed search linked below. PeptideClear publishes editorial commentary, not clinical guidance.
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Thymosin beta-4 and tissue repair
Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Expert Opinion on Biological Therapy, 2012.
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Thymosin beta-4 promotes corneal wound healing
Sosne G, Szliter EA, Barrett R, et al.. Experimental Eye Research, 2002.
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Thymosin beta-4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair
Bock-Marquette I, Saxena A, White MD, et al.. Nature, 2004.
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The effect of thymosin treatment of venous ulcers
Guarnera G, DeRosa A, Camerini R. Annals of the New York Academy of Sciences, 2010.
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Thymosin beta 4 (Fx peptide) is a potent regulator of actin polymerization in living cells
Sanders MC, Goldstein AL, Wang YL. Proceedings of the National Academy of Sciences USA, 1992.
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Thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable
Safer D, Elzinga M, Nachmias VT. Journal of Biological Chemistry, 1991.
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Progress on the Function and Application of Thymosin β4
Xing Y, Ye Y, Zuo H, et al.. Frontiers in endocrinology, 2021.
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Thymosin β4 and Actin: Binding Modes, Biological Functions and Clinical Applications
Ying Y, Lin C, Tao N, et al.. Current protein & peptide science, 2023.
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Thymosin β(4) and β(10) Expression in Human Organs during Development: A Review
Faa G, Messana I, Coni P, et al.. Cells, 2024.
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Purinergic Signaling Involvement in Thymosin β4-mediated Corneal Epithelial Cell Migration
Yang HM, Kang SW, Sung J, et al.. Current eye research, 2020.
Full PubMed search: https://pubmed.ncbi.nlm.nih.gov/?term=thymosin+beta-4+TB-500.
UK regulatory status
Plain-English summary of where TB-500 sits under the four UK and international frameworks that govern peptide supply. Editorial commentary, not legal advice.
- Misuse of Drugs Act 1971: Not controlled under the Misuse of Drugs Act 1971.
- Psychoactive Substances Act 2016: Not scheduled under the Psychoactive Substances Act 2016.
- MHRA medicines classification: No UK marketing authorisation as a medicine.
- WADA Prohibited List: WADA Prohibited List S2 (peptide hormones, growth factors), prohibited at all times.
Full regulatory record: TB-500 UK regulatory status.
Risks and unknowns
What the literature does not yet show about TB-500
Known concerns
- Most published efficacy claims for TB-500 require careful interpretation. Read the cited papers in full before drawing conclusions.
- Purity of UK research-peptide supply varies between retailers. Certificates of analysis and HPLC documentation differ.
- Cold-chain handling between manufacture and delivery is not standardised across the research-peptide market.
- Independent replication of single-group findings is the key check on any preclinical claim.
Open questions in the literature
- Where human pharmacokinetics have not been formally characterised, dose translation from animal models is not reliable.
- Long-term safety profile beyond the duration of published studies remains an open question.
- Interactions with other prescribed or unlicensed substances are typically not studied.
Regulatory note
No UK marketing authorisation as a medicine. Prohibited at all times under WADA S2 (peptide hormones, growth factors). The moment a UK seller or commentator makes a therapeutic claim, MHRA can treat the product as an unlicensed medicinal product.
Important: PeptideClear publishes encyclopedia commentary only and does not recommend human use. Speak to a UK-registered prescriber before any medical decision.
Related reading on PeptideClear
Frequently asked questions
What is the evidence level for TB-500?
What is the UK regulatory status of TB-500?
Has TB-500 been tested in human clinical trials?
Where can I read the source literature for TB-500?
Last verified 2026-05-22. Editorial commentary, not legal or clinical advice. Citations without a linked identifier can be located through the PubMed search and the journal index.