Thymosin Beta-4
The full-length 43-amino-acid peptide naturally produced by the thymus gland — the parent molecule from which TB-500 is derived. Plays a key role in cell movement, tissue repair, wound healing, and reducing inflammation throughout the body. The full-length form may offer broader healing benefits than the TB-500 fragment alone.
Dosage
750 mcg-2 mg subcutaneous 2-3x weekly
Dosages shown are for research reference only. Always consult a qualified healthcare provider.
Administration
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Effects
Tissue Repair
Most abundant actin-sequestering protein — fundamental role in cell migration for healing.
Anti-Inflammatory
Modulates NF-kappaB, reducing TNF-alpha, IL-1beta, and other inflammatory mediators.
Cardiac Repair
Activates cardiac progenitor cells and promotes cardiomyocyte survival.
Mechanism of Action
Thymosin Beta-4 (Tβ4) is a 43-amino-acid peptide and the most abundant member of the beta-thymosin family. Despite its name (derived from its original isolation from thymus tissue), Tβ4 is expressed in virtually every nucleated cell in the body and is particularly concentrated in platelets, wound fluid, and developing tissues. TB-500 is the commercially available active fragment.
The primary molecular function is G-actin sequestration. Tβ4 binds globular actin (G-actin) monomers at a 1:1 stoichiometric ratio through a central actin-binding domain (LKKTET motif), maintaining a large intracellular pool of unpolymerized actin available for rapid mobilization. When cells need to migrate — as during wound healing, inflammation, or development — Tβ4 releases G-actin for polymerization into filamentous actin (F-actin) at the cell's leading edge. This dynamic actin cycling is the fundamental force-generating mechanism for cell migration.
Beyond actin regulation, Tβ4 has extensive signaling functions. It promotes angiogenesis by stimulating endothelial cell migration, tubule formation, and the expression of VEGF and angiopoietin-1. It reduces inflammation by modulating NF-κB signaling, decreasing production of TNF-α, IL-1β, and other pro-inflammatory mediators. In wound healing, Tβ4 upregulates laminin-5 production — a key component of the basement membrane that guides epithelial cell migration during wound re-epithelialization. It activates cardiac progenitor cells and promotes cardiomyocyte survival following ischemic injury, an effect that has generated significant interest for cardiac repair applications.
Tβ4 also promotes stem cell migration and differentiation through activation of the Akt cell survival pathway. It stimulates hair follicle stem cell migration and differentiation, which has been observed as increased hair growth in animal studies. The combination of cell migration, angiogenesis, anti-inflammation, stem cell activation, and extracellular matrix remodeling makes Tβ4 one of the most comprehensive endogenous healing molecules identified.
Regulatory Status
Not FDA approved. Available through compounding pharmacies and research suppliers. TB-500 (the active fragment) is more commonly available. Banned by WADA.
Risks & Safety
Common
injection site irritation, headache, nausea, temporary fatigue.
Serious
may promote existing tumors by stimulating new blood vessel formation and cell movement, no long-term data on effects on tissue remodeling.
Rare
allergic reactions, localized infection.
Compare Thymosin Beta-4 With
Research Papers
30Published: January 19, 2026
AI Summary
Thymosin beta-4 and its metabolite Ac-SDKP protect the kidneys in animal models by reducing cell death, inflammation, and scarring. A review maps how they work and where they may help in acute and chronic kidney injury, though delivery and stability remain hurdles.
Published: January 31, 2026
AI Summary
TB500 and Ac-SDKP, peptides derived from thymosin beta-4, reduced brain inflammation, nerve damage, and memory loss in Alzheimer's mice. They improved neuron survival and axon growth without clearing amyloid plaques, suggesting a new path for AD treatment.
Published: November 30, 2025
AI Summary
Thymosin beta-4 protected brain blood vessel cells from low-oxygen damage and restored barrier function by acting through the S1PR1 receptor. Blocking that receptor removed the benefit, pointing to S1PR1 as a key target for brain injury.
Published: November 13, 2025
AI Summary
Thymosin beta-4 released by stressed mast cells weakened the gut barrier in irritable bowel syndrome via IL22RA1/JAK1/STAT3 signaling. The abstract notes that mast cell mechanisms in IBS remain unclear; full results would clarify the peptide's role.
Published: November 2, 2025
AI Summary
A tandem version of thymosin beta-4 was engineered to last longer and cost less to make than the original peptide. The new design aims to improve corneal wound healing and scale up production for clinical use.
Published: December 30, 2025
AI Summary
The study evaluated whether recombinant human thymosin beta-4 improves heart function after a heart attack in mice and in STEMI patients. The abstract states the aim; full findings would show whether the peptide aids recovery after blood flow is restored.
Published: November 7, 2025
AI Summary
A thymosin beta-4-derived peptide made ovarian cancer cells more sensitive to cisplatin by lowering NF-kappaB. The combo slowed growth, migration, and resistance, suggesting a way to improve chemotherapy response in ovarian cancer.
Published: December 2, 2025
AI Summary
Thymosin beta-4 drives breast cancer growth by turning on SLC7A11, which blocks a form of iron-dependent cell death. Shutting down SLC7A11 reversed the cancer-promoting effects, pointing to a drug target for resistant tumors.
Published: September 30, 2025
AI Summary
A mass spectrometry method identified intact proteins and peptides, including thymosin beta-4, in human brain samples. The technique detected subtle chemical modifications and could help study protein forms in disease.
Published: September 8, 2025
AI Summary
Thymosin beta-4 was low in Alzheimer's brain organoids and patient neurons; adding it back rescued neuron development and reduced amyloid buildup. The peptide may be a target for early AD intervention.
Published: June 30, 2025
AI Summary
A hydrogel loaded with thymosin beta-4 and stem cell exosomes drew stem cells to the site, boosted blood vessel and nerve growth, and sped up skull bone repair in rats. The combo may help heal complex bone defects.
Published: April 25, 2025
AI Summary
Thymosin beta-4 reduced heart scarring after a heart attack by dampening ROCK1 and limiting fibroblast activation. The peptide may act like a ROCK1 inhibitor, offering a new angle for post-heart-attack repair.
Published: July 24, 2025
AI Summary
Microneedle patches loaded with thymosin beta-4-modified stem cell vesicles reversed cell aging and sped up diabetic wound healing in mice. The patches released the vesicles slowly and may help treat hard-to-heal wounds.
Published: July 1, 2025
AI Summary
Living heart slices from humans responded similarly to mice when given cardioprotective genes that boost thymosin beta-4 and prothymosin alpha. The model may offer a faster, cheaper way to test heart repair therapies.
Published: February 25, 2025
AI Summary
Five peptides, including one from thymosin beta-4, improved motor function in zebrafish with Parkinson's-like damage. Three fully reversed the movement impairment, suggesting they may help in Parkinson's disease.
Published: July 17, 2025
AI Summary
Plasmacytoid dendritic cells eased allergic asthma partly by triggering thymosin beta-4 in airway cells. The abstract notes limited knowledge of their role in the effector phase; full results would clarify the mechanism.
Published: February 17, 2025
AI Summary
Proteomics of first heart attack patients identified plasma protein changes, including thymosin beta-4. The abstract states the aim; full findings would show whether the peptide is a useful diagnostic marker.
Published: May 1, 2025
AI Summary
CCN5 limited artery narrowing after stent placement by curbing smooth muscle growth and aiding vessel repair via thymosin beta-4 and Cd9. The findings may help prevent restenosis after heart procedures.
Published: January 21, 2025
AI Summary
Combining stem cells with thymosin beta-4 worked best for dry eye; glutamine was key to the benefit. Blocking glutamine metabolism reversed the effect, pointing to glutamine as a target for dry eye treatment.
Published: February 15, 2025
AI Summary
Thymosin beta-4 helped stem cells pass mitochondria to fat cells through tunneling nanotubes, reducing oxidative stress and improving fat graft survival. The peptide may improve outcomes in fat transfer surgery.
Published: April 2, 2025
AI Summary
Inhaled recombinant human thymosin beta-4 reduced lung scarring in mice with pulmonary fibrosis by acting on the TGF-beta pathway. The peptide may offer a new treatment for idiopathic pulmonary fibrosis.
Published: January 5, 2025
AI Summary
A proteomic analysis of amniotic stem cell secretions identified thymosin beta-4 and beta-10 fragments linked to wound healing and tissue repair. The findings may improve use of these cells in regenerative medicine.
Published: October 22, 2024
AI Summary
Thymosin beta-4 helped zebrafish nerve cells regrow axons after injury by promoting actin assembly. The in vivo work clarifies the peptide's role in nerve regeneration, which had been debated in cell culture studies.
Published: September 23, 2024
AI Summary
Thymosin beta-4 resolved inflammation and infection in bacterial eye infections by activating pro-resolving lipid pathways. The peptide may complement antibiotics by dampening harmful inflammation in keratitis.
Published: July 23, 2025
AI Summary
A study of racehorses established normal thymosin beta-4 levels in blood and showed that synthetic TB4 can be detected via a manufacturing impurity. The work supports doping controls in equine sports.
Published: June 26, 2024
AI Summary
A review tracks thymosin beta-4 and beta-10 expression from fetal life through adulthood in human tissues. The work sheds light on their roles in development, cancer, and the so-called beta-thymosin enigma.
Published: June 12, 2024
AI Summary
A brain gland called the subcommissural organ secretes thymosin beta-4 and beta-10, and restoring these peptides rescued brain development defects in mice. The gland is critical for normal brain formation.
Published: April 10, 2024
AI Summary
Small spleen peptides rich in thymosins shifted dendritic cells toward tolerance by changing extracellular ATP. The peptides reduced psoriatic skin inflammation in mice and may help treat autoimmune disease.
Published: March 30, 2024
AI Summary
The subcommissural organ secretes thymosin beta-4 and beta-10; giving these peptides back to mice with the gland removed rescued brain development. The gland plays a key role in normal brain formation.
Published: June 25, 2024
AI Summary
Lab studies showed thymosin beta-4 improves fat graft survival by acting on adipose-derived stem cells. The abstract notes the mechanism is unclear; full results would clarify how the peptide supports fat retention.
Frequently Asked Questions
What is Thymosin Beta-4?
The full-length 43-amino-acid peptide naturally produced by the thymus gland — the parent molecule from which TB-500 is derived. Plays a key role in cell movement, tissue repair, wound healing, and reducing inflammation throughout the body. The full-length form may offer broader healing benefits than the TB-500 fragment alone.
What is Thymosin Beta-4 used for?
The full-length 43-amino-acid peptide naturally produced by the thymus gland — the parent molecule from which TB-500 is derived. Plays a key role in cell movement, tissue repair, wound healing, and reducing inflammation throughout the body. The full-length form may offer broader healing benefits than the TB-500 fragment alone.
What is the dosage for Thymosin Beta-4?
Loading: 750 mcg-2 mg subcutaneous two or three times weekly for 2-4 weeks. Maintenance: 750 mcg-2 mg subcutaneous once or twice weekly. Some protocols use higher loading doses for acute injuries.
What are the side effects of Thymosin Beta-4?
Common: injection site irritation, headache, nausea, temporary fatigue. Serious: may promote existing tumors by stimulating new blood vessel formation and cell movement, no long-term data on effects on tissue remodeling. Rare: allergic reactions, localized infection.
How does Thymosin Beta-4 work?
Thymosin Beta-4 (Tβ4) is a 43-amino-acid peptide and the most abundant member of the beta-thymosin family. Despite its name (derived from its original isolation from thymus tissue), Tβ4 is expressed in virtually every nucleated cell in the body and is particularly concentrated in platelets, wound fluid, and developing tissues. TB-500 is the commercially available active fragment. The primary molecular function is G-actin sequestration. Tβ4 binds globular actin (G-actin) monomers at a 1:1 stoichiometric ratio through a central actin-binding domain (LKKTET motif), maintaining a large intracellular pool of unpolymerized actin available for rapid mobilization. When cells need to migrate — as during wound healing, inflammation, or development — Tβ4 releases G-actin for polymerization into filamentous actin (F-actin) at the cell's leading edge. This dynamic actin cycling is the fundamental force-generating mechanism for cell migration. Beyond actin regulation, Tβ4 has extensive signaling functions. It promotes angiogenesis by stimulating endothelial cell migration, tubule formation, and the expression of VEGF and angiopoietin-1. It reduces inflammation by modulating NF-κB signaling, decreasing production of TNF-α, IL-1β, and other pro-inflammatory mediators. In wound healing, Tβ4 upregulates laminin-5 production — a key component of the basement membrane that guides epithelial cell migration during wound re-epithelialization. It activates cardiac progenitor cells and promotes cardiomyocyte survival following ischemic injury, an effect that has generated significant interest for cardiac repair applications. Tβ4 also promotes stem cell migration and differentiation through activation of the Akt cell survival pathway. It stimulates hair follicle stem cell migration and differentiation, which has been observed as increased hair growth in animal studies. The combination of cell migration, angiogenesis, anti-inflammation, stem cell activation, and extracellular matrix remodeling makes Tβ4 one of the most comprehensive endogenous healing molecules identified.
How is Thymosin Beta-4 administered?
Thymosin Beta-4 is administered via subcutaneous injection.
What is the half-life of Thymosin Beta-4?
The half-life of Thymosin Beta-4 is 1-2 hours.
Is Thymosin Beta-4 legal?
Not FDA approved. Available through compounding pharmacies and research suppliers. TB-500 (the active fragment) is more commonly available. Banned by WADA.
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