TB 500

TB-500 is a synthetic peptide derived from a naturally occurring protein called thymosin beta-4, which is found in nearly all human and animal cells. It is composed of 43 amino acids and was designed to replicate the biological activity of thymosin beta-4 for research and therapeutic use.

TB-500 is believed to promote tissue repair, reduce inflammation, and enhance cellular regeneration. Studies suggest it may accelerate healing in muscle, tendon, and skin injuries by improving cell migration and blood vessel formation in damaged tissues.

Thymosin beta-4 and its synthetic analog TB-500 accelerate wound repair by promoting cell migration, re-epithelialization, and new blood vessel formation. Animal studies showed faster closure and greater re-epithelialization of full-thickness wounds after Tβ4 treatment ¹. Laboratory and review papers describe additional actions that support tissue repair, including modulation of the actin cytoskeleton to enable cell movement and downregulation of inflammatory chemokines and cytokines ². These mechanisms have been observed across multiple animal models and injury types, supporting TB-500’s reputation for improving tissue regeneration, reducing inflammation, and enhancing angiogenesis.

Beyond skin wounds, Tβ4/TB-500 has shown benefits in muscle, tendon, and heart repair in preclinical studies. Experimental cardiac studies found reduced cardiomyocyte death, stimulated coronary re-growth, and activation of endogenous repair programs after myocardial injury in animals. These encouraging preclinical results motivated early human trials investigating Tβ4 for difficult healing wounds and venous stasis ulcers, indicating translational interest though most evidence remains preclinical ^{3, 4}. Overall, while preclinical data strongly support TB-500’s regenerative and anti-inflammatory effects, further large-scale human trials are needed to confirm its safety, efficacy, and therapeutic potential in clinical use.

In human trials of Thymosin β4 (Tβ4) conducted in healthy volunteers, adverse effects were generally mild and short-lived. One Phase I study that administered single and multiple intravenous doses of up to 1,260 mg daily for 14 days found no serious adverse events or dose-limiting toxicities ⁵. A separate first-in-human trial in China (n ≈ 54) reported only mild to moderate side-effects and no serious adverse events when escalating doses were given for up to 10 days of administration ⁶. Because these studies had short follow-up durations, long-term adverse effects of Tβ4 remain uncharacterised.

TB 500 exerts its effects primarily through regulating actin dynamics. Tβ4 binds to G-actin monomers and sequesters them, thereby modulating actin polymerisation and influencing cell shape, movement, and migration. Beyond actin regulation, Tβ4 promotes cell migration, proliferation, stem/progenitor cell differentiation, angiogenesis (new blood vessel formation), and reduced inflammation and apoptosis in animal models. For example, in rodent wound-healing models, Tβ4 accelerated re-epithelialisation and wound contraction by enhancing endothelial cell migration and vascularisation ^{7, 8}.

In cardiovascular and endothelial contexts, Tβ4 improved outcomes in preclinical studies of myocardial injury and endothelial dysfunction by activating survival signalling in damaged cells, reducing fibrosis, and enhancing new capillary formation. For instance, in a study of endothelial cells derived from induced pluripotent stem cells, Tβ4 improved viability, reduced senescence and endothelin-1 production, and enhanced angiogenic potency under diabetic conditions ⁹.

The FDA has not approved thymosin-β4 / TB-500 for human therapeutic use and has placed thymosin-β4 fragments on its lists of bulk drug substances that raise significant safety concerns for compounding (i.e., the agency lacks adequate safety data and does not support therapeutic/compounding use) ¹⁰. For sports, the World Anti-Doping Agency explicitly lists thymosin-β4 and its derivatives (e.g., TB-500) on the Prohibited List, so use by athletes in tested competition is prohibited ¹¹.