Thymosin Beta-4
WellnessAlso known as: TB-4, Tβ4, Thymosin β4
Limited EvidenceWhat is Thymosin Beta-4?
The full 43-amino acid thymic peptide from which TB-500 is derived. TB-500 is only the active fragment (amino acids 17–23: LKKTET). TB-4 itself has broader biological activity including actin sequestration, anti-inflammatory effects, and tissue repair — though most consumer products labeled TB-4 actually contain the shorter TB-500 fragment.
How it works
Sequesters G-actin monomers through a central LKKTET sequence, modulating actin dynamics critical for cell migration and tissue repair. Also upregulates cell survival proteins, promotes angiogenesis, and reduces inflammatory cytokines. The LKKTET fragment (TB-500) retains actin-binding and pro-healing properties but lacks TB-4's full receptor interactions and systemic immunomodulatory activity.
What marketers claim
- ▸identical to and interchangeable with TB-500
- ▸complete tissue regeneration
- ▸repairs tendons and ligaments in days
- ▸safe for repeated use with no side effects
What evidence supports
- ✓regulates actin dynamics through G-actin sequestration in multiple in vitro and animal models
- ✓promotes wound healing and corneal repair in animal studies
- ✓Phase 2 clinical trial (RegeneRx) for dry eye syndrome showed modest efficacy
- ✓Phase 2 data for venous stasis ulcers and cardiac repair published but inconclusive
Research evidence
Key studies on Thymosin Beta-4, summarized in plain language. This is not an exhaustive list — it highlights the most relevant findings.
Thymosin beta-4 promotes dermal healing
Finding: Significant wound healing acceleration observed in diabetic mouse models treated with thymosin beta-4, including enhanced collagen deposition and re-epithelialization.
Limitation: Animal models; diabetic wound healing may not represent typical human tissue repair scenarios.
Phase 2 trial of thymosin beta4 for pressure ulcers
Finding: Trend toward improved wound healing with thymosin beta-4 vs placebo, but the primary endpoint did not reach statistical significance.
Limitation: Underpowered trial; primary endpoint not met.
Best for
What to expect
Realistic timeline based on available research. Individual results vary.
Week 1–2
Based on animal data: anti-inflammatory effects and early tissue remodeling signals. Human timeline is unknown.
Week 3–6
Animal wound-healing models show measurable repair acceleration. Whether this translates to humans at similar timescales is not established.
Month 2+
Structural repair of tendons and ligaments would require sustained signaling over months. Human data for this timeline does not exist.
Safety notes & concerns
Full safety guide →- ⚠no approved human use anywhere — research chemical only
- ⚠TB-500 and TB-4 are frequently conflated; most products sold as TB-4 are actually the shorter fragment
- ⚠Phase 2 human trials for cardiac repair (MI) were inconclusive and not advanced to Phase 3
- ⚠full TB-4 protein significantly more expensive and less stable than TB-500 fragment
- ⚠no long-term human safety data
Pairs well with
Use caution with
Frequently asked questions
What is the difference between TB-4 and TB-500?
TB-4 is the full 43-amino acid peptide naturally present in human cells. TB-500 is just the active fragment at positions 17–23 (the LKKTET sequence) responsible for actin-binding and healing properties. TB-500 is cheaper, more chemically stable, and easier to synthesize correctly. Most research on "TB-4" in the wellness community is actually conducted using this shorter fragment.
Did TB-4 advance to Phase 3 clinical trials?
No. RegeneRx conducted Phase 2 trials for dry eye syndrome, venous stasis ulcers, and acute myocardial infarction. Results were either modestly positive or inconclusive — none reached statistical thresholds or commercial viability to advance to Phase 3. Development has not meaningfully progressed beyond Phase 2.
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Last updated: 2026-06-10
Medical Disclaimer
The information on this site is for educational and informational purposes only. It is not intended as medical advice and should not be used to diagnose, treat, or prevent any condition. Always consult with a qualified healthcare professional before starting any new supplement, peptide, or treatment protocol.