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TB-500

Thymosin Beta-4 (synthetic fragment)

Synthetic fragment of thymosin beta-4, an actin-sequestering peptide studied in preclinical models of tissue repair, angiogenesis, and inflammation modulation.

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Molecular weight
4963 Da (full Tβ4); fragment varies
Sequence
Variable depending on supplier and fragment
Synonyms
Thymosin β-4, Tβ4 fragment, TB500

What is TB-500?

TB-500 refers to synthetic fragments of thymosin beta-4, a 43-amino-acid peptide naturally present in nearly all human and animal cells. Thymosin beta-4 is best known as the major intracellular G-actin sequestering peptide. Research interest in TB-500 stems from preclinical observations of its effects on cell migration, angiogenesis, and tissue regeneration in animal injury models.

Mechanism of action (preclinical evidence)

TB-500 acts primarily through its actin-binding sequence, mirroring a key functional region of Thymosin Beta-4 (Tβ4). The hexapeptide LKKTET within Tβ4 is the actin-binding site, and TB-500 (residues 17-23) overlaps with this region. Once delivered into cells, TB-500 has been described to sequester G-actin monomers and modulate the actin cytoskeleton, which in turn affects cell motility, migration, and shape change - all critical for wound repair and tissue regeneration. Beyond direct actin interaction, preclinical literature reports that TB-500 upregulates VEGF expression and promotes endothelial cell migration, supporting angiogenesis in injury models. It has also been associated with downregulation of pro-inflammatory cytokines (IL-1β, TNF-α) and induction of anti-inflammatory mediators in macrophage cultures. In cardiac ischemia-reperfusion models, TB-500 has been linked to reduction of infarct size and modulation of cardiomyocyte survival pathways. The protease resistance of TB-500 in plasma (relative to full Tβ4) gives it a longer effective half-life in circulation, which has motivated its choice over full Tβ4 in some preclinical workflows. As with BPC-157, no single high-affinity receptor has been canonically identified - the activity appears to be mediated through multiple intracellular targets and through extracellular actin sequestration.

Research applications

  • Cutaneous wound healing models (full-thickness skin injury)
  • Cardiac infarct repair (rodent ischaemia-reperfusion)
  • Corneal epithelial repair studies
  • Muscle regeneration in dystrophic models
  • Investigation of cell migration and angiogenesis

Storage and handling

Lyophilised TB-500 should be stored at -20 °C, protected from light. Reconstituted solutions are generally less stable - handle in single-use aliquots when possible and follow your laboratory's freeze-thaw protocols.

Deep dive

Read the full research guide for TB-500 to

Mechanism, trial data, sourcing criteria, and verified CoA.

Regulatory status

TB-500 is not approved for human use by any regulator. The natural full-length thymosin beta-4 has been investigated as Tβ4 in some clinical studies for ophthalmic indications, but the synthetic fragments commonly sold as 'TB-500' have a separate research profile. WADA prohibits TB-500 in sport (S0).

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Purity data where applicable · CoA available where applicable · EU shipping

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Frequently asked questions

What is TB-500 and how does it differ from Thymosin Beta-4?+
TB-500 is a synthetic fragment corresponding to residues 17-23 of native Thymosin Beta-4 (Tβ4), specifically the actin-binding region. Full-length Tβ4 is a 43-amino-acid endogenous peptide; TB-500 retains some of its actin-binding and cell-migration effects in a smaller, more accessible form. Some preclinical evidence suggests TB-500 reproduces a subset of Tβ4 activities.
Is TB-500 approved by the FDA?+
No. TB-500 is not approved by FDA, EMA, or any major regulatory body for human or veterinary use. It is sold strictly as a research compound for preclinical laboratory studies.
What research applications does TB-500 have?+
TB-500 is investigated in preclinical models of wound healing, cardiac repair after ischemia, corneal regeneration, and hair follicle biology. Studies often examine its role in promoting cell migration, angiogenesis via VEGF upregulation, and reduction of inflammation in injury models. It has also been studied in equine sports medicine literature.
How is TB-500 stored?+
Lyophilized TB-500 should be kept at -20°C, sealed, protected from light. Once reconstituted in sterile or bacteriostatic water, aliquot and store at 2-8°C; use within 28 days. Avoid repeated freeze-thaw cycles.
Is TB-500 banned in competitive sports?+
Yes. WADA (World Anti-Doping Agency) prohibits TB-500 under category S2 (peptide hormones, growth factors, related substances). The Fédération Equestre Internationale (FEI) also prohibits its use in equine competition.

References

  1. Goldstein AL, et al. Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421-429.
  2. Crockford D, et al. Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications. Ann N Y Acad Sci. 2010;1194:179-189.

Last reviewed: 4 May 2026