TB-500
Thymosin Beta-4 Fragment (TB-500)
Also known as: Thymosin Beta-4, Tβ4, TB4
Prompted by Jack Butcher (Visualize Value) · AI-authored by Claude · Research-sourced
The active fragment of Thymosin Beta-4, promoting cell migration and tissue repair through actin regulation. Frequently combined with BPC-157 for complementary healing pathways.
Quick Facts
Not FDA-approved for human use. Research compound only. Banned by WADA in competitive sports.
Overview
TB-500 is a synthetic version of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide found in virtually all human and animal cells. Thymosin Beta-4 is one of the most abundant intracellular peptides and plays a central role in actin regulation — the protein system that governs cell structure, migration, and tissue repair.
TB-500 specifically refers to the synthetic fragment that replicates the active region of Tβ4. The key active sequence is the N-terminal fragment Ac-SDKP, which is responsible for many of the anti-inflammatory and tissue-repair properties attributed to the full peptide.
Research has demonstrated that TB-500 promotes healing across a range of tissue types including muscle, tendon, ligament, cornea, and cardiac tissue. Its ability to upregulate cell-building proteins such as actin and to promote new blood vessel growth (angiogenesis) makes it a highly studied compound in wound healing and tissue regeneration research.
Mechanism of Action
TB-500 exerts its biological effects primarily through regulation of actin, a critical structural protein in all cells. By sequestering G-actin (globular actin monomers), TB-500 promotes actin polymerization into F-actin filaments, which are essential for cell migration, division, and differentiation.
The peptide upregulates cell surface receptors and promotes the migration of endothelial cells and keratinocytes to injury sites — a process critical for wound closure and tissue repair. It also promotes angiogenesis via upregulation of VEGF and other growth factors, establishing new blood supply to damaged tissues.
TB-500 has potent anti-inflammatory properties, partly mediated through its metabolite Ac-SDKP, which suppresses NF-kB signaling and reduces pro-inflammatory cytokine release. It also reduces oxidative stress and has been shown to decrease fibrosis (scar tissue formation) in cardiac and hepatic injury models, promoting more functional tissue regeneration rather than scarring.
Additionally, TB-500 modulates matrix metalloproteinases (MMPs) which are responsible for extracellular matrix remodeling — a key step in the healing process.
Research Summary
Thymosin Beta-4 and its fragments have been studied in over 70 preclinical studies and several human clinical trials. Dermal wound healing research has shown accelerated closure of full-thickness skin wounds in animal models, with improved angiogenesis and collagen deposition.
Cardiac research is among the most advanced. Studies in murine myocardial infarction models demonstrate that Tβ4 treatment reduces infarct size, decreases fibrosis, and promotes cardiomyocyte survival. The peptide activates resident cardiac progenitor cells, suggesting a mechanism for cardiac regeneration rather than simple repair.
Ophthalmic research led to the development of RGN-259, a topical Tβ4 formulation for dry eye and neurotrophic keratopathy, which advanced to Phase III clinical trials (RegeneRx Biopharmaceuticals). This represents the most advanced clinical development of any Tβ4-based therapy.
Neurological studies show neuroprotective effects in traumatic brain injury and stroke models, with improved functional recovery and reduced inflammation. TB-500 promotes oligodendrocyte differentiation and remyelination in experimental autoimmune encephalomyelitis models.
In musculoskeletal research, TB-500 has been studied for tendon and ligament repair, showing accelerated healing and improved biomechanical properties in Achilles tendon injury models.
Key References
Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair
Bock-Marquette I, et al. · Nature (2004) · 10.1038/nature02517
Landmark study demonstrating that Tβ4 promotes cardiac cell migration and survival after myocardial infarction via integrin-linked kinase (ILK) activation.
Thymosin β4 promotes dermal wound healing via its actin-binding domain
Philp D, et al. · Journal of Investigative Dermatology (2004) · 10.1111/j.0022-202X.2004.22603.x
Demonstrated that the actin-binding domain of Tβ4 is essential for its wound healing effects, including increased angiogenesis, collagen deposition, and keratinocyte migration.
Thymosin beta-4 and the eye: the peptide with many functions
Sosne G, Ousler GW. · Expert Opinion on Biological Therapy (2015) · 10.1517/14712598.2015.1044887
Review of the ophthalmic applications of Tβ4, including clinical trial results for dry eye and corneal wound healing with the RGN-259 formulation.
Ac-SDKP, a peptide released from thymosin β4, inhibits collagen deposition in cardiac fibroblasts
Peng H, et al. · Cardiovascular Research (2014) · 10.1093/cvr/cvu039
Demonstrated the anti-fibrotic mechanism of Ac-SDKP (Tβ4 metabolite) in cardiac tissue, showing reduced collagen I and III synthesis in fibroblasts.
Thymosin β4 promotes angiogenesis, wound healing, and hair follicle development
Philp D, et al. · Annals of the New York Academy of Sciences (2007) · 10.1196/annals.1389.024
Broad review of Tβ4 tissue-repair properties including angiogenesis, wound healing, and stimulation of hair follicle stem cells.
Protocols
Systemic healing / injury recovery
Common loading protocol: 2.5 mg twice weekly for 4–6 weeks, followed by 2.5 mg every 2 weeks for maintenance. Inject subcutaneously in the abdominal area or near the injury site.
Acute injury protocol
Higher loading dose used in community protocols for acute injuries. Taper to 2.5 mg twice weekly after the initial period. Often combined with BPC-157.
Research dose (preclinical reference)
Preclinical doses are significantly higher on a per-kg basis than typical community protocols. Human equivalent doses (HED) calculated using FDA body surface area scaling.
Side Effects & Safety
| Frequency | Effect |
|---|---|
| common | Injection site redness or irritation Mild and typically resolves within hours. Rotating injection sites helps minimize this. |
| uncommon | Temporary lethargy or fatigue Some users report mild tiredness in the hours following injection, particularly at higher doses. |
| uncommon | Headache Usually mild and transient. More commonly reported during the loading phase. |
| rare | Head rush or lightheadedness Reported anecdotally, typically immediately after injection. |
| rare | Nausea Infrequently reported, usually resolves without intervention. |
Contraindications
- —Active cancer or history of cancer (theoretical concern due to angiogenic and cell-proliferative properties)
- —Pregnancy or breastfeeding
- —Active infections (Tβ4 may theoretically promote pathogen spread via increased cell migration)
- —Competitive athletes subject to WADA testing (TB-500 is a prohibited substance)
Interactions
- —May interact with anticoagulant medications due to effects on blood vessel formation and remodeling
- —Theoretical interaction with immunosuppressive drugs via immune cell modulation
- —May potentiate the effects of other angiogenic agents or growth factors
Reconstitution & Storage
Related Peptides
TB-500 is most commonly combined with BPC-157 for enhanced tissue healing. The two peptides target complementary mechanisms — TB-500 promotes actin regulation and cell migration while BPC-157 drives angiogenesis and growth factor upregulation. This combination is widely used in community healing protocols.