A synthetic fragment of Thymosin Beta-4, a 43-amino-acid protein involved in cell migration, wound healing, and anti-inflammation. Widely used in veterinary and research settings for tissue repair.
TB-500 is a synthetic version of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid protein found in nearly all human and animal cells. Tβ4 is one of the most abundant intracellular peptides and plays a critical role in cell motility, wound healing, and anti-inflammatory signaling.
Unlike BPC-157 (which promotes healing primarily through angiogenesis), TB-500 works by sequestering G-actin — the monomeric form of actin — which promotes cell migration, blood vessel formation, and tissue remodeling. It has been most extensively studied in equine (horse racing) veterinary medicine and is commonly stacked with BPC-157 for complementary healing effects.
TB-500 is rich in charged residues (Lys, Glu, Asp), making it highly hydrophilic and water-soluble. The key functional motif is the actin-binding domain LKKTETQ (residues 17-23), which is essential for G-actin interaction. The N-terminal tetrapeptide AcSDKP has independent anti-fibrotic activity.
TB-500's primary mechanism is actin cytoskeleton regulation. Actin is the most abundant protein in eukaryotic cells and is essential for cell movement, division, and structural integrity. By controlling the G-actin/F-actin balance, TB-500 directly influences how quickly cells can migrate to damaged tissue.
| Pathway | Effect | Significance |
|---|---|---|
| G-actin sequestration | Binds monomeric actin to prevent premature polymerization | Ensures actin availability for cell migration when needed |
| AcSDKP release | The N-terminal tetrapeptide AcSDKP is anti-fibrotic | Reduces scar tissue formation and promotes functional tissue regeneration |
| Laminin/integrin upregulation | Increases cell surface adhesion receptors | Enhances cell attachment to extracellular matrix at injury sites |
| Anti-inflammatory | Reduces IL-1β, TNF-α, and other inflammatory cytokines | Creates an environment conducive to healing rather than chronic inflammation |
TB-500's preclinical evidence spans cardiac, dermal, neurological, and musculoskeletal applications.
| Study Area | Design | Key Findings | Evidence |
|---|---|---|---|
| Cardiac repair | Mouse MI model | Reduced infarct size, improved ejection fraction, promoted cardiomyocyte survival post-heart attack | Preclinical |
| Wound healing | Rat/mouse dermal wounds | Accelerated wound closure, increased angiogenesis and collagen deposition | Preclinical |
| Corneal healing | Rat corneal injury | Accelerated epithelial migration and wound closure | Preclinical (Phase II human attempted) |
| Equine tendon | Horse tendon injuries | Widely used in horse racing; improved tendon healing and return to performance | Veterinary clinical |
| Neurological | Rat TBI/stroke models | Promoted neuronal survival and functional recovery; stimulated oligodendrocyte differentiation | Preclinical |
Generally well-tolerated: No significant adverse effects reported in preclinical studies at standard doses.
Cancer concern (theoretical): Tβ4 is overexpressed in some tumor cells. While TB-500 has not been shown to promote cancer, caution is advised in patients with active malignancies.
Lack of long-term data: No chronic toxicity studies in humans. Long-term effects unknown.
Quality control: As a research peptide, purity varies between suppliers. No pharmaceutical-grade consumer products exist.
| Jurisdiction | Status |
|---|---|
| FDA | Not approved for any indication |
| WADA | Banned under S0 (non-approved substances) |
| Veterinary | Widely used in equine medicine (not FDA-approved for animals) |
| Feature | TB-500 | BPC-157 |
|---|---|---|
| Size | 43 amino acids (4,963 Da) | 15 amino acids (1,419 Da) |
| Origin | Thymus gland (Thymosin β4) | Human gastric juice protein |
| Primary mechanism | G-actin sequestration → cell migration | VEGFR2-Akt-eNOS → angiogenesis |
| Key action | Promotes cell migration to injury site | Builds new blood vessels to injured tissue |
| Oral bioavailability | No (injection only) | Yes (stable in gastric juice) |
| Best for | Systemic inflammation, muscle, cardiac | Tendons, gut, localized injuries |
| Combined use | Commonly stacked — complementary mechanisms (angiogenesis + cell migration) |