Thymosin beta-4 fragment
TB-500
A short thymosin beta-4-related fragment; it should not be treated as interchangeable with full-length thymosin beta-4.
Why it is discussed
Wound-healing and soft-tissue recovery claims
TB-500 is discussed in injury-recovery communities for wound, tendon, muscle, and mobility claims. FDA identifies no human exposure data for the TB-500 fragment it reviewed, so laboratory or animal findings cannot establish a safe or effective human use.
What it is
A product name that must be tied to an actual peptide sequence.
An analytical study identified the material in a marketed TB-500 preparation as Ac-LKKTETQ, an acetylated seven-amino-acid fragment corresponding to part of thymosin beta-4. That fragment is not the full thymosin beta-4 molecule.
Because commercial naming can be ambiguous, the label TB-500 alone does not establish what a vial contains. Evidence about a fragment, a metabolite, or full-length thymosin beta-4 must remain tied to that specific material.
How it works
Investigating cell migration and metabolites.
Tissue-repair claims often borrow from research on thymosin beta-4 and cell movement. Similarity to a region of a larger peptide does not demonstrate that the smaller fragment reproduces the larger molecule's actions.
A study of TB-500 metabolism also tested the fragment and its breakdown products in a fibroblast wound-closure assay. Only one tested metabolite, Ac-LKKTE, significantly improved closure under those experimental conditions. A scratch closing in a layer of cultured cells is not the same as an injured tendon healing in a person.
These findings do not establish a validated human repair mechanism, clinical benefit, or safe use for products labeled TB-500.
Scientific / evidence sources
Evidence at a glance
What is established—and what is not.
Preclinical and molecule-adjacent evidence
Thymosin beta-4 biology and preclinical wound-healing research provide a mechanistic rationale for discussion.
The marketed TB-500 fragment is not interchangeable with full-length thymosin beta-4, and FDA reports no identified human exposure data for the reviewed fragment.
Regulatory status
Canada and the United States are checked separately.
Health Canada lists injectable TB-500 among unauthorized peptide drugs and advises consumers not to buy or use such products.
No FDA-approved product. FDA describes absent human exposure data plus immunogenicity and peptide-impurity concerns.
Regulatory status describes product authorization and relevant regulatory context. It is not a complete legal opinion about possession, importation, prescribing, sale, or professional practice.
If you are reviewing a product report
The molecule profile and the testing report answer different questions.
This page summarizes evidence and regulatory context. A laboratory report may address identity, purity, or quantity for one submitted sample; it does not transfer clinical evidence or product authorization.