TB-500 (Thymosin Beta-4): Research Overview, Mechanisms, and Current Evidence
TB-500 is a synthetic peptide related to thymosin beta-4 (Tb4), a naturally occurring 43-amino-acid actin-binding protein found in nearly all human cells. Much of the published research uses full-length thymosin beta-4, which has been studied in preclinical and early clinical settings for cell migration, angiogenesis, and tissue repair. The information below summarizes published research for educational and research purposes only. It is not medical advice and is not guidance for use in humans.
Available for research use from our preferred vendor, Project Zero. For laboratory research use only.
How It Works (Preclinical Mechanisms)
In preclinical models, thymosin beta-4 has been reported to bind actin and influence pathways linked to cell migration, blood vessel formation, and tissue repair.
- Binds and sequesters monomeric G-actin, a function studied in cell migration and cytoskeletal remodeling.
- Reported to promote angiogenesis (new blood vessel formation) and endothelial cell migration in experimental models.
- Investigated for anti-inflammatory and anti-apoptotic effects in tissue-injury models, including activation of survival signaling.
- In cardiac models, reported to act through the ErbB2 signaling pathway to limit cardiomyocyte loss after ischemia.
Areas of Research Interest
Published studies have examined thymosin beta-4 and related peptides in the following research contexts. Evidence ranges from animal models to early-phase human trials.
Cardiac repair after ischemia
Studied in animal models of myocardial infarction and in early human trials for effects on cardiac function and infarct size.
Corneal and wound healing
Investigated in eye and skin models, with thymosin beta-4 reaching clinical trials for dry eye and corneal repair.
Angiogenesis and tissue remodeling
Examined in models of blood vessel formation and cell migration relevant to repair after injury.
Fibrosis models
Studied in kidney and other organ models, where its degradation product Ac-SDKP has shown antifibrotic activity.
Reported Study Parameters
For laboratory research use only. The table below reports the doses and routes used in specific published studies, with sources. It describes what researchers administered in these models and is not a protocol, recommendation, or guidance for use in humans or animals. Animal-study doses are expressed per kilogram of body weight.
| Research Model | Dose and Route Reported | Source |
|---|---|---|
| Healthy volunteers (Phase I, recombinant human Tb4) | Single intravenous dose 0.05 to 25.0 ug/kg; repeat dosing 0.5, 2.0, or 5.0 ug/kg per day for 10 days | Wang 2021·DOI |
| Healthy volunteers (Phase I, synthetic Tb4) | Single intravenous dose 42 to 1260 mg, then the same dose daily for 14 days | Ruff 2010·DOI |
| Human research (acute myocardial infarction, Phase II) | Recombinant human Tb4 given within 8 hours after PCI in a 96-patient trial; no validated regimen established | Zhang 2025·DOI |
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Latest Research (2021 to 2026)
Recent peer-reviewed literature indexed on PubMed continues to characterize how thymosin beta-4 works while clarifying how early the human evidence remains, especially for the marketed TB-500 fragment.
Peptides in sports medicine (review)
A 2026 narrative review examined approved and unapproved peptides marketed to patients, including TB-500 and thymosin beta-4, and reported that many show favorable tissue-repair outcomes in animal models while rigorous human safety data remain scarce. PubMed·DOI
Cardiac repair (mouse and human)
A 2025 study reported that recombinant human thymosin beta-4 improved cardiac function and reduced fibrosis in a mouse ischemia-reperfusion model through ErbB2 signaling, and described a randomized trial in 96 patients with ST-elevation myocardial infarction, while noting that larger studies are needed. PubMed·DOI
Corneal infection and healing
A 2023 paper reviewed thymosin beta-4 as an adjunct to antibiotics in bacterial keratitis, reporting that topical thymosin beta-4 reduced inflammation and supported corneal wound healing in experimental models, with the peptide also in Phase 3 trials for dry eye disease. PubMed·DOI
Phase I safety and pharmacokinetics
A 2021 first-in-human Phase I trial of recombinant human thymosin beta-4 in healthy volunteers reported that single and multiple intravenous doses were well tolerated with no dose-limiting toxicities, supporting further study in acute myocardial infarction. PubMed·DOI
Research Questions
How does TB-500 relate to thymosin beta-4?
TB-500 is a synthetic peptide marketed as being related to thymosin beta-4, the naturally occurring actin-binding protein. Most published research uses full-length thymosin beta-4 rather than the marketed fragment, so findings should be read with that distinction in mind.
What is the current state of human evidence?
Human research includes Phase I safety trials and early-phase trials for acute myocardial infarction and ophthalmic conditions. No regimen has been validated for general use.
What does the available safety literature suggest?
Phase I trials of recombinant human thymosin beta-4 reported good tolerability without dose-limiting toxicity, but human data remain limited and long-term safety has not been established, particularly for the unapproved TB-500 fragment.
Referenced Citations
Literature indexed on PubMed.
- Mendias, C.L., & Awan, T.M. (2026). Safety and efficacy of approved and unapproved peptide therapies for musculoskeletal injuries and athletic performance. Sports Med. PubMed·DOI
- Zhang, Y., et al. (2025). Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion. Cardiovasc. Res., 121(17), 2747-2758. PubMed·DOI
- Sosne, G., & Berger, E.A. (2023). Thymosin beta 4: A potential novel adjunct treatment for bacterial keratitis. Int. Immunopharmacol., 118, 109953. PubMed·DOI
- Wang, X., et al. (2021). A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin beta 4 in healthy Chinese volunteers. J. Cell. Mol. Med., 25(17), 8222-8228. PubMed·DOI
- Ruff, D., et al. (2010). A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta 4 in healthy volunteers. Ann. N. Y. Acad. Sci., 1194, 223-229. PubMed·DOI
- Zuo, Y., et al. (2013). Thymosin beta 4 and its degradation product, Ac-SDKP, are novel reparative factors in renal fibrosis. Kidney Int., 84(6), 1166-1175. PubMed·DOI
PeptideInfo.org provides information strictly for educational and research purposes. All referenced products are intended for laboratory and research use only and are not approved for human consumption, medical use, or self-administration. Nothing on this page constitutes medical advice. Research summaries reference literature indexed on PubMed.