TB-500: Thymosin β4 fragment
A synthetic fragment of thymosin β4 studied (mostly as the full protein, in animals) for cell migration, tissue repair and recovery — not FDA-approved.
What is TB-500?
TB-500 is a synthetic peptide based on the actin-binding region of thymosin β4 (Tβ4), a naturally occurring protein involved in cell movement and tissue repair. An important caveat: most of the research is on the full Tβ4 protein in animal and cell models — the TB-500 fragment itself has no completed human efficacy trials, and it is not FDA-approved. It is most often discussed for soft-tissue and muscle recovery, frequently alongside BPC-157.
Published-literature summary: A synthetic fragment of Thymosin Beta-4, TB-500 promotes actin polymerization, cell migration, angiogenesis, and tissue remodeling. Animal research demonstrates accelerated muscle fiber repair, tendon healing, and reduced inflammation. Often combined with BPC-157 in research stacks. (Goldstein & Kleinman (2015) — Ann NY Acad Sci; Philp & Bhattacharya (2017) — Expert Opin Investig Drugs)
How TB-500 works (mechanism)
Thymosin β4 works largely by binding and sequestering G-actin, regulating the actin cytoskeleton that cells use to move and reshape [2]. Through this actin regulation it is linked in animal and cell studies to cell migration, focal-adhesion dynamics, new blood-vessel formation (angiogenesis, partly via VEGF) and wound healing [1][3]. TB-500 is the fragment that carries this actin-binding activity — but note that most of this mechanistic evidence comes from the full-length protein, not the fragment.
Why it's studied / reported uses
Soft-tissue & muscle recovery
Animal and cell studies of thymosin β4 report enhanced cell migration and angiogenesis relevant to muscle, tendon and other soft-tissue repair — for example, improving outcomes in an ischemic-limb model [4]. These are preclinical findings on the full protein; human evidence for the TB-500 fragment is lacking.
Wound healing & tissue repair (research)
Full-length Tβ4 has been studied for dermal wound healing and other tissue repair, and Phase 1 human safety studies of thymosin β4 have been run in healthy volunteers [5][6]. These involve the full protein — not the TB-500 fragment sold for recovery.
Dosing reported in studies
Route: subcutaneous
From community/veterinary-derived protocols; not human-trial validated.
Route: subcutaneous
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Sources: Goldstein & Kleinman (2015) — Ann NY Acad Sci · Philp & Bhattacharya (2017) — Expert Opin Investig Drugs
A synthetic Thymosin β4 fragment. Human dosing not established in controlled trials. These figures reflect what studies or protocols reported — not a recommendation and not tailored to you.
Calculate a dose in the reconstitution calculator →Common combinations & stacks
Wolverine Stack (BPC-157 + TB-500)
TB-500 is most commonly paired with BPC-157. The reported rationale: TB-500 is associated with systemic cell migration and broad soft-tissue turnover, while BPC-157 is associated with local repair and angiogenesis at an injury site. This is a community protocol with no controlled human evidence; neither peptide is FDA-approved and both are prohibited in sport by WADA.
Safety & side effects
TB-500 is not FDA-approved and is prohibited by WADA as a growth-factor modulator affecting tissue repair [7]. Critically, there are no completed human safety trials of the fragment, so short- and long-term effects are essentially unknown. Because thymosin β4 promotes cell migration and angiogenesis, reviewers raise theoretical caution in settings such as active cancer, though this is not established in humans. Research-chemical sourcing also carries purity, dosing-accuracy and contamination risks. Always consult a licensed physician.
Studies & references
- Progress on the function and application of thymosin β4 (review) — NCBI / PMC8724243
- Thymosin β4, actin sequestering, and hypoxia/NO regulation — NCBI / PMC4182666
- Thymosin β4 regulates focal adhesion formation and cell migration — NCBI / PMC6935720
- Thymosin β4 enhances stem-cell efficacy in a mouse ischemic-hindlimb model — NCBI / PMC7139370
- Phase 1a study of thymosin β4 in healthy volunteers — ClinicalTrials.gov NCT04555824
- Phase 1b study of thymosin β4 in healthy volunteers — ClinicalTrials.gov NCT04555850
- TB-500 — status, risks and bans in sport (WADA-prohibited) — BSCG (Banned Substances Control Group)
Frequently asked questions
Is TB-500 the same as thymosin beta-4?
Not exactly. TB-500 is a synthetic peptide based on the actin-binding fragment of thymosin β4. Most published research studies the full β4 protein, so fragment-specific human data are limited.
Is TB-500 FDA-approved?
No. TB-500 is not FDA-approved for any use, is generally sold as a research chemical, and is banned in competitive sport by WADA.
What is TB-500 used for?
In research it's studied mainly for cell migration, angiogenesis and soft-tissue/muscle recovery — largely in animals and largely with the full β4 protein rather than the fragment.
How is TB-500 dosed in studies?
There is no established human dose for the fragment. Commonly reported community protocols use roughly 2–2.5 mg twice weekly for a loading period, then less often (see the dosing section). This is not a recommendation.
What are TB-500's risks?
Because there are no completed human safety trials of the fragment, short- and long-term risks are largely unknown. Research-chemical products may also vary in purity and dosing accuracy.
⚠ Research & educational use only. This page is compiled from published research and does not constitute medical advice. TB-500 is not FDA-approved and generally sold as a research chemical. Nothing here is a recommendation to use or a prescription. Safe use can only be determined by a licensed physician. Last updated 2026-07-06.