Synthetic actin-binding fragment of thymosin β4

TB-500

Established

Also known as Thymosin β4 fragment

The migration-and-angiogenesis peptide behind the recovery hype.

Cited sources: 2
Human-tested claims: 1 of 3
Best evidence: Tier 1 · Established
Status: Research-only

A short synthetic peptide (Ac-LKKTETQ) taken from the actin-binding motif of thymosin β4. Most of the cited healing research actually used the full 43-amino-acid thymosin β4 protein — not this fragment — a distinction the recovery marketing tends to blur.

repairangiogenesisinvestigational

How it works

The LKKTET motif in thymosin β4 binds actin and is linked to cell migration, new blood-vessel formation, and wound repair. TB-500 isolates that motif as a small peptide, but it is chemically distinct from the full protein and behaves differently in the body.

Sequence: Ac-LKKTETQA synthetic ~7-residue N-acetylated fragment of thymosin β4 (full protein: 43 residues, UniProt P62328). TB-500 and native thymosin β4 are not interchangeable.

What it's studied for

One claim per card, each with its own tier and source. Tiers 1 and 2 are human data. Tiers 3 and 4 are not yet.

Full-length thymosin β4 promotes cell migration and angiogenesis in vitro and in animal wound models.
Preclinical
[1]Goldstein et al., 2005 (Ann N Y Acad Sci)(opens in a new tab)
TB-500 is a synthetic Ac-LKKTETQ fragment of thymosin β4, not the native protein.
Established
[2]UniProt — thymosin β4 (P62328)(opens in a new tab)
No human clinical trial has tested the TB-500 fragment itself for recovery or injury.
Emerging

Safety & limitations

No human safety data exist for the fragment. Its angiogenesis-promoting activity is a theoretical concern that has not been characterized in people.

[1]Goldstein et al., 2005 (Ann N Y Acad Sci)

Regulatory & legal status

Research-only

Not approved for human use. (Full-length thymosin β4 has been studied clinically for eye conditions, but that is the whole protein, not the TB-500 fragment.)

[2]UniProt — thymosin β4 (P62328)

Frequently asked

Is TB-500 the same as thymosin β4?

No. TB-500 is a small synthetic fragment (Ac-LKKTETQ); thymosin β4 is the full 43-amino-acid protein. Most healing studies used the full protein, so their results don't automatically apply to TB-500.

References

Written by Twenty Residues editorial. Medical review: pending; a named reviewer is being assigned.

Last updated September 19, 2026.

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Update history

2026-09-19 — Sourced review — every claim checked against primary literature; sequence, regulatory status, safety, and FAQs added.