TB-500
Also known as: Thymosin Beta-4 Fragment, Ac-LKKTETQ, Tβ4 Active Fragment
Overview
TB-500 is a synthetic heptapeptide corresponding to the N-acetylated active fragment (amino acids 17–23) of the endogenous 43-amino acid signaling protein thymosin beta-4. First isolated from thymus tissue in the 1960s, thymosin beta-4 is one of the most abundant G-actin sequestering molecules in mammalian cells. The TB-500 fragment retains the key LKKTET sequence responsible for much of the biological activity while offering improved bioavailability.
Mechanism of Action
TB-500's primary mechanism involves high-affinity binding to monomeric G-actin (Kd ~0.5-0.7 μM), sequestering it and preventing polymerization into F-actin filaments. This enables rapid cytoskeletal remodeling critical for cell migration and wound closure. Additional mechanisms include VEGF mRNA upregulation (2.5-3.8 fold), enhanced endothelial cell migration and angiogenesis, NF-κB pathway inhibition reducing pro-inflammatory cytokines (TNF-α, IL-1β, IL-6 by 40-60%), stem cell mobilization via the SDF-1α/CXCR4 axis, and modulation of extracellular matrix through MMP expression regulation.
Potential Benefits
- Accelerated wound closure rates 40-55% faster than controls in diabetic models
- Reduced inflammation through NF-κB inhibition and cytokine modulation
- Improved muscle flexibility and reduced scar formation
- Cardiac protection with ejection fraction improvements of 15-25% post-MI in animal models
- Enhanced re-epithelialization and improved tissue quality
- Stem cell mobilization to sites of injury
- Corneal, dermal, and cardiac tissue repair support
Dosage Protocols
The following reflects doses used in published research studies. This is not medical advice. Consult a qualified healthcare professional.
| Typical Range | 2-5 mg/week |
| Beginner | 2 mg/week |
| Intermediate | 2.5-4 mg/week |
| Advanced | 5-7 mg/week |
| Cycle Duration | 4-8 weeks loading, then maintenance |
| Cycle Off | 4-8 weeks |
Often used in a loading phase (2x/week) for 4 weeks followed by a maintenance phase (once/week). Doses are in mg, not mcg, due to the larger peptide size.
Use our Reconstitution Calculator to determine exact syringe units for your protocol.
Routes of Administration
Subcutaneous Injection High
Standard route; well tolerated; inject into abdominal fat or near injury site
Intramuscular Injection High
Alternative to subcutaneous; may achieve faster onset for deep muscle injuries
Read our full Routes of Administration Guide for detailed comparison of all delivery methods.
Stacking Protocols
Popular research stacks involving TB-500:
Ultimate Recovery Stack
Synergistic tissue repair across all tissue types
The most popular peptide combination; TB-500 handles systemic inflammation and actin remodeling while BPC-157 provides targeted cytoprotection and vascular repair.
Cardiac Protection Stack
Cardioprotection and mitochondrial function support
TB-500's proven cardioprotective effects in post-MI models combined with mitochondrial-targeting peptides.
Athletic Performance Stack
Injury prevention, muscle growth, and recovery optimization
TB-500 supports connective tissue health while GH axis peptides drive anabolism and recovery.
Explore our complete Peptide Stacking Guide for more combinations and safety considerations.
Reconstitution
| Typical Vial Size | 5mg, 10mg |
|---|---|
| BAC Water | 1-2ml per 5mg vial |
| Storage | Refrigerate at 2-8°C after reconstitution |
| Shelf Life | 28-30 days refrigerated |
Need exact syringe measurements?
Amino Acid Sequence
Ac-SDKPDMAEIEKFDKSKLKKTETQEKNPLPSKETIEQEKQAGES (full Tβ4); Active fragment: Ac-LKKTETQ
Side Effects & Safety
- Potential tumor growth promotion (theoretical concern with angiogenic activity)
- Flu-like symptoms reported anecdotally
- Lethargy immediately post-injection in some cases
- Long-term human safety data lacking
Synergistic Compounds
The following compounds have been studied alongside TB-500 for potential complementary or synergistic effects:
Learn More
References & Further Reading
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