TB-500
Not FDA-approved
Also known as: Ac-LKKTETQ, Thymosin beta-4 fragment (LKKTETQ)
TB-500 is a lab-made fragment of thymosin beta-4: seven of the protein's 43 amino acids, with an acetyl group added at the front. It is a different substance from full-length thymosin beta-4. No clinical trial has tested it in people.
How it works
- It copies amino acids 17 to 23 of thymosin beta-4, the stretch that binds actin, a protein cells use to move. Researchers credit this region with part of the full protein's role in wound healing.
- The acetyl cap is artificial, added when the peptide is made. It removes a positive charge at the front end, which may change how it binds.
- In lab tests and in horses, it is broken down into shorter peptides.
Evidence
Wound and tissue repair
No clinical trial in people has tested TB-500. In a small 2026 rat study, material labelled TB-500 made repaired Achilles tendons stronger and better organized. The paper did not confirm what the material contained. A 2025 animal study of eye burns used a modified version of the fragment in a gel.
Caveats
- Human trials of thymosin beta-4, in eye, heart and leg-ulcer patients, used the full 43-amino-acid protein. Those results do not apply to TB-500.
- No published safety studies of this fragment in people or animals were found.
- In lab studies, colon cancer cells that made extra thymosin beta-4 became more invasive and migrated more. Whether TB-500 has any such effect is unknown; it has not been tested.
- The name TB-500 is often confused with full-length thymosin beta-4, and products sold under it raise concerns about identity and purity.
References
This page is for education only. It is not medical advice. Decisions about any treatment belong with a physician who knows your history.