Archive: January 2026

What is TB-500?

TB-500 is a synthetic peptide fragment corresponding to the active region of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid protein involved in cell motility, differentiation, and survival. CAS number: 77591-33-4. It is supplied as a lyophilized powder for in vitro and preclinical research.

Thymosin Beta-4 was first isolated from the thymus gland in the 1960s and has since been identified in virtually all mammalian cell types. The synthetic fragment TB-500 replicates the actin-binding domain of the full protein, which is central to its biological activity in research models.

Mechanism of Action

Actin Sequestration and Polymerization

The primary documented mechanism of TB-500 involves its interaction with the actin cytoskeleton. TB-500 binds to monomeric G-actin, preventing premature polymerization into F-actin filaments. This sequestration creates a pool of available actin monomers that can be rapidly deployed for cytoskeletal reorganization — a process essential for cell migration, wound closure, and tissue remodeling.

Cell Migration Promotion

In both in vitro scratch assays and in vivo wound models, TB-500 has been observed to promote directional cell migration. The mechanism appears related to its effects on actin dynamics: by maintaining a readily available pool of G-actin, cells at wound edges can rapidly extend lamellipodia and migrate into the wound space.

Anti-Inflammatory Observations

Several published studies have reported anti-inflammatory effects associated with TB-500 administration in preclinical models. In rodent cardiac injury models, TB-500 treatment was associated with reduced inflammatory cell infiltration and decreased expression of pro-inflammatory cytokines relative to controls. The mechanism underlying these observations has not been fully elucidated.

Research Applications

Wound Healing and Dermal Repair

The most established research application for TB-500 involves wound healing models. Multiple studies have demonstrated accelerated wound closure in rodent models, with increased angiogenesis (new blood vessel formation) at wound sites. These effects have been attributed to both the actin-related migration enhancement and upregulation of vascular endothelial growth factor.

Cardiac Injury Models

Published work in mouse models of myocardial infarction has shown that TB-500 administration post-injury was associated with reduced scar size and improved cardiac function metrics compared to untreated controls. These studies have generated significant interest in Tβ4 biology, though translation to human cardiac research remains in early stages.

Corneal and Ocular Research

TB-500 has been studied in corneal wound healing models, where its effects on epithelial cell migration are particularly relevant. This research has progressed further toward clinical investigation than most other applications, with the full-length Tβ4 protein having entered clinical trials for ophthalmic indications under the name RGN-259.

Limitations and Considerations

As with most peptide research, the TB-500 literature is predominantly preclinical. Rodent and cell culture models make up the vast majority of published data. The translation gap between these models and any human application remains significant.

Researchers should also note that TB-500 (the synthetic fragment) and full-length Thymosin Beta-4 are not identical in all contexts. While they share the actin-binding domain, the full protein contains additional functional regions that may contribute to biological effects observed in some studies.

Specifications

CAS Number: 77591-33-4. Form: Lyophilized powder. Purity: ≥98% (HPLC). Storage: -20°C. Available strength: 10 mg.

All TB-500 from Vial & Error Labs includes a lot-specific COA and GHS-compliant SDS. For research use only.