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Safe TB-500

Where to find each study and rule

TB-500 references for every numbered claim

The list includes journal articles, a Phase 1 human safety test, a withdrawn ClinicalTrials.gov public record, and dated FDA pages.

Back to study resultsRead federal rules

What each bracketed number points to

Research teams tested two different things. One was TB-500, the small lab-made copy. The other was the full thymosin beta-4 protein. Their lab weights are 889 daltons and 4963 daltons, in that order. A dalton is an atom-sized lab weight unit. Most studies listed below used the full protein. Each results page tells you which form the team gave. Square-bracket numbers match the numbered entries below. Entries [16]–[18] are dated FDA pages about pharmacy rules. The full reference list is directly below this note.

  1. Irobi E, Aguda AH, Larsson M, et al. Structural basis of actin sequestration by thymosin-beta4: implications for WH2 proteins. EMBO J. 2004;23(18):3599-3608. ↗
  2. Malinda KM, Sidhu GS, Mani H, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. ↗
  3. Bock-Marquette I, Saxena A, White MD, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. ↗
  4. Ruff D, Crockford D, Girardi G, Zhang Y. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. ↗
  5. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin beta4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. ↗
  6. Tokura Y, Nakayama Y, Fukada S, et al. Muscle injury-induced thymosin beta4 acts as a chemoattractant for myoblasts. J Biochem. 2011;149(1):43-48. ↗
  7. Xiong Y, Mahmood A, Meng Y, et al. Thymosin beta4 enhances the healing of medial collateral ligament injury in rats. Regul Pept. 2013;184:1-8. ↗
  8. Morris DC, Chopp M, Zhang L, Zhang ZG. A dose-response study of thymosin beta4 for the treatment of acute stroke. J Neurol Sci. 2014;345(1-2):61-67. ↗
  9. Spurney CF, Cha HJ, Sali A, et al. Evaluation of skeletal and cardiac muscle function after chronic administration of thymosin beta-4 in the dystrophin deficient mouse. PLoS One. 2010;5(1):e8976. ↗
  10. Kleinman HK, Sosne G. Thymosin beta4 promotes dermal healing. Animal studies with thymosin beta, a multifunctional tissue repair and regeneration peptide (including porcine ischemia-reperfusion data). Ann N Y Acad Sci. 2010;1194:118-122. ↗
  11. RegeneRx Biopharmaceuticals (sponsor). A Study of the Safety and Efficacy of Injectable Thymosin Beta 4 for Treating Acute Stroke (withdrawn). ClinicalTrials.gov identifier NCT01311518. 2011. ↗
  12. Jo JO, Kang YJ, Ock MS, et al. Thymosin beta4 induces the expression of vascular endothelial growth factor (VEGF) in a hypoxia-inducible factor (HIF)-1alpha-dependent manner. Biochim Biophys Acta. 2010;1803(11):1244-1251. ↗
  13. Kleinman HK, Sosne G, Goldstein AL. Thymosin beta4 and cancer: pro-migratory and pro-angiogenic properties implicated in tumor progression and metastasis (review of the oncologic safety signal). Expert Opin Biol Ther. 2012;12(Suppl 1). ↗
  14. Qiu P, Wheater MK, Qiu Y, Sosne G. Thymosin beta4 promotes matrix metalloproteinase expression during wound repair. J Cell Physiol. 2006;209(2):611-617. ↗
  15. Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med. 2026. ↗
  16. Gonzalez-Franquesa A, Stocks B, Borg ML, et al. Discovery of thymosin beta4 as a human exerkine and growth factor. Am J Physiol Cell Physiol. 2021;321(5):C770-C778. ↗
  17. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding That May Present Significant Safety Risks (list entry: 'Thymosin beta-4, fragment (LKKTETQ), also known as TB-500'; Category 2, effective September 29, 2023). ↗
  18. U.S. Food and Drug Administration. Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act (Category 1 and Category 2 definitions; 503A/503B framework; nomination and PCAC process). ↗
  19. U.S. Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee (agenda lists 'TB-500 (free base)' / 'TB-500 acetate', BPC-157, KPV, and MOTs-C as substances being considered for inclusion on the 503A Bulks List; a scheduled discussion, not a decision). ↗
  20. Cha HJ, Jeong MJ, Kleinman HK. Role of thymosin beta4 in tumor metastasis and angiogenesis. J Natl Cancer Inst. 2003. ↗
  21. Wang WS, et al. Thymosin beta 4 is overexpressed in human pancreatic cancer cells and stimulates proinflammatory cytokine secretion and JNK activation. Cancer Biol Ther. 2008. ↗
  22. Cooper TM, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry. J Chromatogr A. 2012. ↗
  23. Thomas A, et al. TB500/TB1000 and SGF1000: A scientific approach for a better understanding of doping-relevant peptide preparations. Drug Test Anal. 2023. ↗