TB-500

TB-500 is a synthetic peptide closely related to thymosin beta-4 (Tβ4), a naturally occurring 43-amino-acid protein that is one of the most abundant intracellular peptides in mammalian cells and a major regulator of cellular actin dynamics. The research literature investigating TB-500 and Tβ4 has been published in journals including Nature, Trends in Molecular Medicine, Frontiers in Pharmacology, and the International Journal of Molecular Sciences, and includes preclinical mechanism work, animal-model tissue-repair studies, and one published Phase 3 trial of a topical Tβ4 ophthalmic formulation (RGN-259) in neurotrophic keratopathy.

In the foundational 2004 Bock-Marquette study published in Nature, Tβ4 was reported to activate integrin-linked kinase and promote cardiac cell migration, survival, and cardiac repair in a mouse myocardial-injury model [1]. The Sosne 2022 Phase 3 trial of 0.1% RGN-259 (Tβ4 ophthalmic solution) in neurotrophic keratopathy patients reported that the formulation promotes healing and improves comfort versus vehicle in a randomized, placebo-controlled, double-masked design [2]. Mechanistic work characterizing Tβ4 as an actin-sequestering protein that moonlights to repair injured tissues has been comprehensively reviewed by Goldstein, Hannappel, and Kleinman in Trends in Molecular Medicine [3].

TB-500 is not approved by the FDA, EMA, or any other regulatory authority for any indication. The related Regenera Pharma compound RGN-259 (a 0.1% Tβ4 ophthalmic solution) has been advanced through Phase 3 trials in neurotrophic keratopathy and dry eye disease, but a regulatory approval for the ophthalmic formulation has not yet been granted as of the most recent published trial data.

Important Note on the Evidence Base

Important note on the evidence base: Most peer-reviewed research on the TB-500 / Tβ4 axis is preclinical, involving rodent models of cardiac injury, dermal wound healing, corneal injury, and skeletal-muscle repair, alongside in vitro cell-culture mechanism work. The Sosne 2022 Phase 3 trial in neurotrophic keratopathy evaluated a topical ophthalmic formulation (RGN-259) and is the most rigorous published clinical evidence to date. There are no published Phase 3 trials of systemic TB-500 administration in humans. Researchers consulting this page should weight study design and route of administration accordingly.

Mechanism of Action

Thymosin beta-4 is a multifunctional intracellular peptide whose research literature has expanded from its original characterization as an actin-sequestering protein to encompass tissue-repair, anti-inflammatory, and pro-survival activities across multiple injury models.

Actin sequestration. The classical biochemical activity of Tβ4 is binding to monomeric (G-actin) actin molecules with 1:1 stoichiometry, preventing their polymerization into filamentous (F-actin) form. By regulating the G-actin/F-actin equilibrium, Tβ4 modulates cytoskeletal dynamics in ways that affect cell shape, migration, and division. The 2005 Goldstein, Hannappel, and Kleinman review in Trends in Molecular Medicine synthesized the actin-sequestration biology with the emerging tissue-repair literature, framing Tβ4 as a moonlighting protein whose intracellular biochemical role is complemented by extracellular signaling activities released after cell injury or secretion [3].

Cardiac repair and integrin-linked kinase activation. The Bock-Marquette 2004 study in Nature reported that intraperitoneal administration of Tβ4 in a mouse myocardial-infarction model promoted survival of cardiomyocytes, migration of embryonic and adult cardiac cells, and improved cardiac function 4 weeks post-injury [1]. The investigators characterized the mechanism as activation of integrin-linked kinase (ILK) with downstream Akt phosphorylation, providing a defined intracellular signaling pathway linking Tβ4 administration to cardioprotection. The Postrach 2014 study in Frontiers in Pharmacology subsequently reported that systemic administration of Tβ4 produced cardioprotective effects in a rat model of ischemic myocardial injury [4].

Corneal and ocular repair. The Sosne 2022 Phase 3 trial used a 0.1% RGN-259 ophthalmic solution applied topically to the affected eye in patients with neurotrophic keratopathy, a serious corneal disease characterized by impaired corneal innervation and persistent epithelial defects [2]. The investigators reported significant improvements in corneal healing and patient-reported comfort metrics. The corneal-repair indication has been supported by preclinical models of corneal injury, where Tβ4 has been reported to promote re-epithelialization, reduce inflammation, and improve healing.

Wound healing and inflammation. Across multiple preclinical wound-healing models — dermal, hepatic, neural, and others — Tβ4 has been reported to promote tissue repair through a combination of pro-migratory, pro-survival, and anti-inflammatory effects. The mechanistic literature has invoked actin sequestration, ILK–Akt signaling, vascular endothelial growth factor (VEGF) modulation, and inhibition of NF-κB–driven inflammatory gene programs as contributors to the integrated tissue-repair phenotype.

Available Forms

Omnix Peptides currently supplies TB-500 in a single research format. Each lot is independently characterized by HPLC and LC–MS, with a batch-specific Certificate of Analysis available on the product page.

• TB-500 Vial — lyophilized powder for reconstitution. Multiple strengths available per vial. The vial is the canonical research format used in the preclinical literature evaluating Tβ4 and Tβ4-derived peptides via parenteral administration. (The Phase 3 RGN-259 ophthalmic formulation studied by Sosne and colleagues uses a topical 0.1% aqueous formulation, which is not Omnix’s research format.)

TB-500 is classified under the Recovery & Healing research category. For research framed around tissue repair more broadly, see also the related compound hubs for BPC-157, GHK-Cu, and the combination BPC+TB Blend — all classified under the recovery research category, with complementary but mechanistically distinct profiles.

Amount in the Published Research Literature

The following amount ranges describe the protocols used in the peer-reviewed Tβ4 / TB-500 literature. They are reported here for research-reference purposes only and do not constitute administration recommendations of any kind.

Bock-Marquette 2004 cardiac repair model. The foundational Nature study used intraperitoneal administration of Tβ4 at approximately 150 µg per mouse, administered before and after coronary artery ligation, in a mouse myocardial-infarction model [1]. The investigators assessed cardiomyocyte survival, cardiac cell migration, and ventricular function over a 4-week post-injury period.

Postrach 2014 systemic cardioprotection model. The rat ischemic myocardial-injury study evaluated systemic Tβ4 administration via intravenous infusion, reporting cardioprotective effects on infarct size and ventricular remodeling [4]. Researchers should consult the primary article for full amount schedule and vehicle-composition detail.

Sosne 2022 Phase 3 ophthalmic trial. The Phase 3 trial in neurotrophic keratopathy patients used 0.1% RGN-259 (Tβ4 ophthalmic solution) applied topically to the affected eye, with the administration frequency and duration specified in the trial protocol [2]. The topical ophthalmic route is not directly translatable to systemic administration protocols.

Note on TB-500 vs. Tβ4. TB-500 is widely used as a research-chemical name for peptides related to thymosin beta-4. The published preclinical and clinical literature is on the parent Tβ4 protein or on defined fragments of it; researchers using TB-500 in research protocols should be explicit about the exact peptide sequence, length, and stability profile of their material, since these characteristics affect biological activity and study reproducibility.

Researchers planning protocols are referred to the original primary literature cited in the References section for full methodological detail.

Frequently Asked Questions

References

1. Bock-Marquette I, Saxena A, White MD, DiMaio JM, Srivastava D. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. doi:10.1038/nature03000
2. Sosne G, Kleinman HK, Springs C, Gross RH, Sung J, Kang S. 0.1% RGN-259 (Thymosin β4) ophthalmic solution promotes healing and improves comfort in neurotrophic keratopathy patients in a randomized, placebo-controlled, double-masked Phase III clinical trial. Int J Mol Sci. 2022;24(1):554. doi:10.3390/ijms24010554 · PubMed: 36613994
3. Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. 2005;11(9):421-429. doi:10.1016/j.molmed.2005.07.004
4. Postrach J, Schmidt M, Thörmer J, et al. Cardioprotection by systemic administration of thymosin beta four following ischemic myocardial injury. Front Pharmacol. 2014;5:36. doi:10.3389/fphar.2014.00036

For Research Use Only. The product described on this page is sold strictly for in vitro laboratory research and is not intended for human or animal consumption, diagnostic use, or therapeutic use. The published research summarized above is provided as scientific reference material. Nothing on this page constitutes medical advice, a therapeutic claim, or a recommendation for any use outside of a properly resourced and ethically reviewed research setting.