TB-500
Synthetic Fragment (17-23) of Thymosin Beta-4
A synthetic 7-amino acid fragment corresponding to the actin-binding region of thymosin beta-4, originally developed for equine use with retained tissue repair properties. TB-500 acts as principal actin-sequestering protein, regulating cell migration, promoting angiogenesis, reducing inflammation, and activating stem cell differentiation.
Overview
A synthetic 7-amino acid fragment corresponding to the actin-binding region of thymosin beta-4, originally developed for equine use with retained tissue repair properties. TB-500 acts as principal actin-sequestering protein, regulating cell migration, promoting angiogenesis, reducing inflammation, and activating stem cell differentiation.
Acts as principal actin-sequestering protein, regulating cell migration, promoting angiogenesis, reducing inflammation, and activating stem cell differentiation for comprehensive regenerative effects.
Research indications
What the compound has been studied for, grouped by body system. Effect size is the reported magnitude where it was measured — not a recommendation.
Accelerated healing of muscle fibers with reduced recovery time and enhanced repair via cell migration and differentiation.
Connective tissue repair with reduced scar formation and improved biomechanical properties of healing tissues.
Enhanced dermal closure, improved angiogenesis, and reduced inflammation in acute and chronic scenarios.
Faster recovery from intense training with reduced muscle soreness and improved tissue repair.
Strengthened tissues through enhanced repair mechanisms may reduce injury risk.
Improved muscle quality through enhanced regeneration and repair pathways.
Protective effects against neuronal damage in various models.
Preclinical evidence for improved outcomes in spinal injury models.
Potential neuroprotective and regenerative effects on brain tissue.
A large effect in a weak study and a small effect in a strong one are different things. Effect size is never evidence of use in people.
- Class
- Thymosin fragment
- Chain length
- 43 residues
- Molecular weight
- 4963.44 Da
- Half-life
- ~2 h
- Typical dose
- 2-5mg per injection (higher doses for serious injuries)
- Frequency
- 2-3x weekly (e.g., Monday, Wednesday, Friday)
- Cycle length
- 6-8 weeks for active healing
- Storage
- Reconstituted: 2-8°C, use within 28 days
Molecular data
- Type
- Thymosin fragment
- Molecular weight
- 4963.44 Da
- Chain length
- 43 residues
- Half-life
- 120 min
Dosing reference
Doses reported in the literature and by suppliers. These are a record of what has been used in research — reference, never instruction.
| Context | Route | Amount | Frequency |
|---|---|---|---|
| General tissue repair | SubQ or IM | 2-3mg | 2x weekly |
| Serious injury recovery | SubQ near injury site | 4-5mg | 3x weekly |
| Athletic enhancement | SubQ | 2-3mg | 2x weekly |
| Chronic conditions | SubQ or IM | 3-4mg | 2-3x weekly |
| Maintenance | SubQ | 2mg | 1-2x weekly |
| Post-surgical recovery | SubQ | 3-5mg | 3x weekly |
| Chronic wound healing | Topical application | 0.01-0.03% concentration | 1-2x daily |
| Dry eye treatment | Ophthalmic | Eye drops formulation | As directed |
Interactions
Complementary healing mechanisms with enhanced tissue repair when combined (Wolverine Stack).
May enhance tissue sensitivity to growth hormone effects.
Combined tissue repair with GH-releasing effects for comprehensive recovery.
Enhanced muscle and tissue regeneration through complementary growth pathways.
No negative interactions; potential enhanced recovery.
Different receptor families with no pathway overlap.
Quality checklist
- ✓White lyophilized powder - fine, evenly distributed with light fluffy texture
- ✓Clear, colorless solution after reconstitution with no particles
- ✓Proper vacuum seal intact with secure rubber stopper
- !Slight powder clumping acceptable if completely dissolves with gentle swirling
- ×Colored or crystalline powder (yellow/brown indicates degradation)
- ×Persistent cloudiness, floating particles, or precipitation
- ×Damaged vial seal or contamination signs
What to expect
Safety
- Generally minimal side effects
- Possible mild injection site reactions
- Temporary fatigue in some users
- Persistent or worsening injection site infections
- Unusual swelling or prolonged redness
- Severe allergic reactions
- Unexpected systemic symptoms
- Concerning health changes
- Active cancer treatment (due to angiogenic effects)
- Pregnancy or breastfeeding
- Immunosuppressive medications (consult provider)
- WADA prohibited for competitive athletes
FAQ
Can TB-500 be injected directly at the injury site or must it be systemic?
TB-500 can be injected directly near injury sites or systemically. Local injection near tendon/ligament injuries may accelerate healing by concentrating effects, but systemic SubQ or IM administration provides comprehensive tissue repair through systemic circulation and is more commonly used.
How long do TB-500 benefits persist after stopping the protocol?
TB-500's healing benefits persist for weeks to months after completing a 6-8 week cycle due to sustained improvements in tissue quality, angiogenesis, and stem cell mobilization. However, maintenance doses every 1-2 weeks may be needed for chronic conditions requiring ongoing support.
Is TB-500 banned in sports and why?
Yes, TB-500 is prohibited by WADA in competitive sports because it enhances cellular regeneration and muscle repair, providing unfair athletic advantage. Athletes should avoid use if subject to anti-doping testing.
What's the difference between TB-500 and the TB-500 fragment (Ac-LKKTETQ)?
Full TB-500 is the complete 43-amino-acid thymosin beta-4, while the fragment is just the bioactive 7-amino-acid core (LKKTETQ). Both work similarly, but the fragment is smaller, more stable, and potentially more economical while retaining core wound-healing and regenerative properties.
References
- 1Development of thymosin beta4 for treatment of patients with ischemic heart diseaseCrockford, D. · Annals of the New York Academy of Sciences · 2007
Synthetic thymosin beta-4 given intravenously was well tolerated with no dose-limiting toxicity; promotes cardiomyocyte migration and survival, and stimulates coronary vasculogenesis for cardiac ischemia treatment.
human-pilotPubMed 17947592 ↗ - 2Evaluation of skeletal and cardiac muscle function after chronic administration of thymosin beta-4 in the dystrophin deficient mouseSpurney, C.F., et al. · PLoS One · 2010
Chronic thymosin beta-4 administration increased the number of regenerating skeletal muscle fibers in exercised dystrophin-deficient (mdx) mice, showing potential for Duchenne muscular dystrophy treatment.
animalPubMed 20126456 ↗ - 3The regenerative peptide thymosin beta-4 accelerates the rate of dermal healing in preclinical animal models and in patientsTreadwell, T., Kleinman, H.K., Crockford, D., Hardy, M.A., Guarnera, G.T., Goldstein, A.L. · Annals of the New York Academy of Sciences · 2012
In two Phase 2 clinical trials, thymosin beta-4 accelerated healing of chronic pressure ulcers and venous stasis ulcers by almost a month compared to placebo, with confirmed safety and tolerability.
animalPubMed 23050815 ↗ - 4Thymosin beta-4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trialSosne, G., Dunn, S.P., Kim, C. · Cornea · 2015
Phase 2 randomized trial in 9 severe dry eye patients showed RGN-259 (0.1% thymosin beta-4) eye drops achieved statistically significant improvements in both signs and symptoms, with effects lasting 28 days post-treatment.
human-rctPubMed 25826322 ↗ - 5A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteersWang X, Liu L, Qi L, et al. · Journal of Cellular and Molecular Medicine · 2021
Phase I trial in 54 healthy subjects demonstrated recombinant thymosin β4 was well tolerated and safe across ascending IV doses up to 25 μg/kg with no significant accumulation.
human-rctPubMed 34346165 ↗ - 60.1% RGN-259 (Thymosin beta-4) Ophthalmic Solution Promotes Healing and Improves Comfort in Neurotrophic Keratopathy Patients in a Randomized, Placebo-Controlled, Double-Masked Phase III Clinical TrialSosne, G., Kleinman, H.K., Springs, C., Gross, R.H., Sung, J., Kang, S. · International Journal of Molecular Sciences · 2022
Phase III trial demonstrated thymosin beta-4 ophthalmic solution promotes corneal healing and improves comfort in neurotrophic keratopathy, advancing toward FDA approval.
human-rctPubMed 36613994 ↗