Summary

Thymosin Beta-4 (Tβ4) is a 43-amino-acid peptide found in virtually all human cells. Its primary biological function is binding to G-actin, regulating the cellular cytoskeleton and promoting cell migration — making it a key mediator of wound healing, tissue repair, and inflammation control. Tβ4 has been investigated in clinical trials for acute myocardial infarction, dry eye disease, and multiple sclerosis, with the strongest signal in preclinical wound healing models. TB-500 is the market name commonly applied to synthetic Tβ4 or its active fragments. The peptide is not licensed as a medicine by the MHRA in the UK.

Mechanism

Tβ4's primary mechanism is the binding and sequestration of G-actin (globular actin), preventing its polymerisation into F-actin (filamentous actin). By maintaining a pool of monomeric actin, Tβ4 enables rapid actin polymerisation at sites where cell motility is needed — such as wound edges. This actin-regulating function underlies its effects on cell migration (keratinocytes, endothelial cells, cardiac cells), angiogenesis (through upregulation of VEGF and promotion of endothelial cell tube formation), and tissue repair. Tβ4 also has anti-inflammatory properties, including downregulation of pro-inflammatory cytokines (TNF-α, IL-1β) and modulation of NF-κB signalling. Additionally, Tβ4 has been shown to promote anti-apoptotic signalling and protect cells from oxidative stress.

Protocols

In clinical trials, Tβ4 has been administered at 0.5–6 mg intravenously or subcutaneously. The STEMI trial used a single 6 mg IV dose. In research peptide contexts, 2–5 mg per week subcutaneously over 4–6 week cycles is commonly discussed. These figures are from published literature and community discussion only; Tβ4 is not licensed in the UK.

Thymosin Beta-4 / TB-500 is not licensed by the MHRA in the UK. It is not a controlled substance. Sold as a research peptide, it is legal to purchase for legitimate laboratory research but not for human consumption without appropriate regulatory authorisation.

Vendor notes

TB-500 is widely available from UK research peptide suppliers. Because products labelled TB-500 may contain full-length Tβ4 or truncated fragments, researchers should verify the exact sequence and purity via independent COAs. Look for vendors specifying the 43-amino-acid sequence and providing mass spectrometry data.

References

  1. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin beta4: a multi-functional regenerative peptide. Expert Opin Biol Ther. 2020;20(7):755-766. doi:10.1080/14712598.2020.1745770
  2. Sosne G, Qiu P, Goldstein AL, Wheater M. Biological activities of thymosin beta4 defined by active sites in short peptide sequences. Ann N Y Acad Sci. 2010;1194:14-26. doi:10.1111/j.1749-6632.2010.05470.x
  3. Crockford DN, Rosenberg M, Bhatt D, et al. Thymosin beta4 improves cardiac function in a mouse model of myocardial infarction. J Mol Cell Cardiol. 2009;47(6):796-804. doi:10.1016/j.yjmcc.2009.03.130
  4. Smart N, Risebro CA, Melville AA, et al. Thymosin beta4 induces adult epicardial progenitor mobilization and neovascularization. Nature. 2007;445(7124):177-182. doi:10.1038/nature05383
  5. Sosne G, Szliter EA, Barrett R, et al. Thymosin beta 4 promotes corneal wound healing and decreases inflammation in alkali-injured mouse cornea. Immunol Lett. 2002;82(1-2):69-74. doi:10.1016/s0165-2478(02)00017-x
  6. Philp D, Kleinman HK. Animal studies with thymosin beta4, a multifunctional tissue repair and regeneration peptide. Ann N Y Acad Sci. 2010;1192:81-86. doi:10.1111/j.1749-6632.2010.05547.x
  7. Low TL, Hu SK, Goldstein AL. Complete amino acid sequence of bovine thymosin beta 4: a thymic hormone that induces terminal deoxynucleotidyl transferase activity in thymocyte populations. Proc Natl Acad Sci USA. 1981;78(2):1162-1166. doi:10.1073/pnas.78.2.1162