TB-500
Synthetic fragment of thymosin β4
A name used for synthetic versions of thymosin β4, a small actin-binding protein present in most cells. Products sold as TB-500 range from a short fragment to the full 43-residue protein. Research on the full protein is far larger than on the fragment.
Structure
Shown here as the acetylated 7-residue actin-binding fragment. Some suppliers sell full-length thymosin β4 (43 residues, about 4963 g/mol) under the same name, so check the COA. Select any residue to see what it is.
Evidence at a glance
Where the published research on TB-500 comes from, by type of study.
Cell studies
Actin sequestration, cell migration and wound-closure assays, mostly with full thymosin β4.
Animal studies
Cardiac injury, corneal wounds and skin repair in mice and rats.
Human studies
Eye-drop and wound trials have tested full thymosin β4. The short fragment sold as TB-500 has no published human trials.
Research areas
What laboratories have studied TB-500 for, and in which models. These are research questions, not proven uses.
Cell migration and actin
Scratch-wound assaysEndothelial cells- Binds G-actin and regulates the actin cytoskeleton.
- Promotes migration of endothelial cells and keratinocytes in vitro.
Cardiac repair models
Mouse myocardial infarction- Full thymosin β4 improved cardiac cell survival and vessel growth in mice.
- Studied for activation of epicardial progenitor cells.
Corneal and skin wounds
Rodent corneal injuryRodent skin wounds- Faster corneal epithelial healing in animal models.
- Faster skin wound closure in rats.
Legal status
TB-500 is not an approved medicine anywhere we cover. Suppliers may sell it for laboratory research only, and regulators judge that by the whole website, not the label.
United States Not approved
Not FDA-approved. In July 2026 an FDA advisory committee voted to recommend TB-500 for the 503A bulks list; the vote is not binding and no rule had been proposed as of 27 October 2026. Research material may be sold for laboratory use only.
United Kingdom Not licensed
No MHRA licence. Sold with medicinal claims it counts as a medicine under the Human Medicines Regulations 2012.
European Union Not authorised
No EMA authorisation. Under Directive 2001/83/EC a substance can be a medicine by function, whatever its label says.
Sport Prohibited
Thymosin β4 and its derivatives, including TB-500, are named on the WADA Prohibited List.
Lab handling
General good practice for research materials. Follow the supplier's datasheet where it differs.
Storage
Keep the sealed material at −20 °C, dry and away from light. Let the vial reach room temperature before opening to stop condensation.
Solubility
Generally soluble in sterile water or buffer. Add solvent down the vial wall and swirl gently rather than shaking.
Aliquots
Split solutions into single-use aliquots, label with lot number and date, and freeze. Avoid repeated freeze-thaw cycles.
Work out your stock solution
Stock concentration, molarity and dilutions for TB-500, using MW 889 g/mol.
Before you buy for your lab
Tick each check as you confirm it with the supplier. Do not order until all six are done.
Questions researchers ask
What is TB-500?
A name used for synthetic versions of thymosin β4, a small actin-binding protein present in most cells. Products sold as TB-500 range from a short fragment to the full 43-residue protein. Research on the full protein is far larger than on the fragment.
What is the molecular weight of TB-500?
About ≈889 g/mol for the free peptide. Salt forms such as acetate weigh more, so use the figure on your batch certificate of analysis.
Is TB-500 approved for human use?
No. Not FDA-approved. In July 2026 an FDA advisory committee voted to recommend TB-500 for the 503A bulks list; the vote is not binding and no rule had been proposed as of 27 October 2026. Research material may be sold for laboratory use only.
How should TB-500 be stored in the lab?
Keep the sealed material cold, dry and away from light, typically at −20 °C. Once in solution, split it into single-use aliquots and freeze to avoid repeated freeze-thaw cycles.
Does this page give doses?
No. We publish laboratory and educational information only, never doses, injection guidance or treatment advice.
Is TB-500 legal in the US after the July 2026 FDA vote?
It is still not FDA-approved. On 23–24 July 2026 the FDA Pharmacy Compounding Advisory Committee narrowly voted to recommend adding BPC-157, KPV, TB-500, MOTS-c, Epitalon and Semax to the 503A bulks list, against the advice of FDA staff. The vote is not binding. As of 27 October 2026 no rule has been proposed, and an interim access policy for compounding pharmacies has been under White House review since 14 October 2026. None of this changes the position of research-use-only sellers. Read our explainer on the July 2026 FDA vote.
Is TB-500 legal in the UK?
TB-500 it is not licensed by the MHRA. Selling it with medicinal claims makes it an unlicensed medicine under the Human Medicines Regulations 2012, so UK suppliers can only offer it for laboratory research.
Is TB-500 the same as thymosin beta-4?
No. Thymosin β4 is a 43-amino-acid protein. TB-500 is a synthetic 7-amino-acid fragment (Ac-LKKTETQ) based on its actin-binding region. Sellers sometimes use the names interchangeably, so check the sequence and molecular weight on the certificate of analysis.
What is the amino acid sequence of TB-500?
TB-500 is usually described as Ac-Leu-Lys-Lys-Thr-Glu-Thr-Gln (Ac-LKKTETQ), with a molecular weight of about 889 g/mol.
What is the half-life of TB-500?
There is no reliable published half-life for TB-500 in humans. No reliable human pharmacokinetic data have been published, so treat any half-life figure quoted by sellers with caution.
TB-500 vs BPC-157: what is the difference?
TB-500 comes from thymosin β4 and is linked to actin binding and cell migration. BPC-157 is a fragment of a gastric protein. Both are studied in tissue-repair models and both are banned by WADA. See our BPC-157 profile or the full BPC-157 vs TB-500 comparison.
Is TB-500 banned by WADA?
Yes. Thymosin β4 and its derivatives, including TB-500, are named on the WADA Prohibited List.
