# TB-500 References: Cited Studies on Thymosin Beta-4 and the LKKTETQ Fragment

> TB-500 references — the peer-reviewed studies, the FDA 503A source pages, and the PCAC agenda cited across this digest, with DOIs, PMIDs and URLs for thymosin beta-4 and the Ac-LKKTETQ fragment.

Every quantitative claim on this site maps to a numbered entry below — peer-reviewed studies, FDA pages, and the PCAC meeting agenda.

## How these references are used

This is the full study reference list for the digest. Research findings come from the peer-reviewed literature on thymosin beta-4 and the Ac-LKKTETQ fragment; the regulatory facts on the [TB-500 legal status](/legal-status) page come from FDA pages and the FDA Pharmacy Compounding Advisory Committee agenda, listed separately below [16][17][18]. Where a study used full-length thymosin beta-4 rather than the 7-mer, that is noted in the body where the finding appears.

## Peer-reviewed studies and reviews

Entries 1–15 are the research citations carried inline across the digest. Hair-follicle and tissue-repair findings (1–5, 8), mechanism and structural work (6), consolidated reviews (7, 12), cardiac, neurological and angiogenic studies (9, 10, 11), the human Phase 1 of full-length thymosin beta-4 (13), the withdrawn stroke trial (14), and the 2026 Sports Medicine review of unapproved peptides (15) are all listed in the index with DOIs, PMIDs or trial identifiers.

## Regulatory sources

Entries 16–19 are the FDA and FDA-advisory sources behind the legal-status page: the FDA significant-safety-risks listing that places the LKKTETQ fragment (also known as TB-500) in Category 2 [16], the FDA Section 503A bulk-substances framework page [17], the July 23–24, 2026 PCAC meeting agenda naming TB-500 among substances being considered for the bulks list [18], and the FDA access-pathway framework for compounded medications [19].

## References

[1] Philp D, et al. Thymosin beta4 increases hair growth by activation of hair follicle stem cells. FASEB J. 2004;18(2):385-387. https://pubmed.ncbi.nlm.nih.gov/14657002/
[2] Philp D, et al. Thymosin beta 4 induces hair growth via stem cell migration and differentiation. Ann N Y Acad Sci. 2007;1112:95-103. https://pubmed.ncbi.nlm.nih.gov/17947589/
[3] Gao X, et al. Thymosin Beta-4 Induces Mouse Hair Growth. PLoS One. 2015;10(6):e0130040. https://pubmed.ncbi.nlm.nih.gov/26083021/
[4] Xiao X, et al. Multiple potential roles of thymosin β4 in the growth and development of hair follicles. J Cell Mol Med. 2021;25(3):1350-1358. https://pubmed.ncbi.nlm.nih.gov/33393222/
[5] Philp D, et al. Thymosin beta4 promotes angiogenesis, wound healing, and hair follicle development. Mech Ageing Dev. 2004;125(2):113-115. https://pubmed.ncbi.nlm.nih.gov/15037013/
[6] Irobi E, et al. Structural basis of actin sequestration by thymosin-beta4: implications for WH2 proteins. EMBO J. 2004;23(18):3599-3608. https://pubmed.ncbi.nlm.nih.gov/15329672/
[7] Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. 2012;12(1):37-51. https://pubmed.ncbi.nlm.nih.gov/22074294/
[8] Malinda KM, et al. Thymosin beta4 accelerates wound healing. J Invest Dermatol. 1999;113(3):364-368. https://pubmed.ncbi.nlm.nih.gov/10469335/
[9] Bock-Marquette I, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. 2004;432(7016):466-472. https://pubmed.ncbi.nlm.nih.gov/15565145/
[10] Morris DC, et al. A dose-response study of thymosin β4 for the treatment of acute stroke. J Neurol Sci. 2014;345(1-2):61-67. https://pubmed.ncbi.nlm.nih.gov/25060418/
[11] Jo JO, et al. Thymosin β4 induces the expression of vascular endothelial growth factor (VEGF) in a hypoxia-inducible factor (HIF)-1α-dependent manner. Biochim Biophys Acta. 2010;1803(11):1244-1251. https://pubmed.ncbi.nlm.nih.gov/20691219/
[12] Kleinman HK, Sosne G. Animal studies with thymosin beta, a multifunctional tissue repair and regeneration peptide. Ann N Y Acad Sci. 2010;1194:118-122. https://pubmed.ncbi.nlm.nih.gov/20536453/
[13] Ruff D, et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin β4 in healthy volunteers. Ann N Y Acad Sci. 2010;1194:223-229. https://pubmed.ncbi.nlm.nih.gov/20536472/
[14] RegeneRx (sponsor). A Study of the Safety and Efficacy of Injectable Thymosin Beta 4 for Treating Acute Stroke (WITHDRAWN). ClinicalTrials.gov, 2011. Identifier NCT01311518. https://clinicaltrials.gov/study/NCT01311518
[15] Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Med. 2026. https://pubmed.ncbi.nlm.nih.gov/41966639/
[16] 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'; effective 2023-09-29). https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
[17] 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; bulks-list and nomination framework). https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act
[18] U.S. Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee (agenda listing BPC-157, KPV, TB-500, and MOTs-C as bulk drug substances being considered for inclusion on the 503A Bulks List). https://www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026
[19] U.S. Food and Drug Administration. Human Drug Compounding — Section 503A patient-specific compounding and 503B outsourcing-facility framework (access pathway: licensed-prescriber evaluation, valid prescription, dispensing by a 503A pharmacy or sourcing from a 503B outsourcing facility, subject to ingredient-eligibility requirements). https://www.fda.gov/drugs/guidance-compliance-regulatory-information/human-drug-compounding

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A luminous reading of the TB-500 record — the Ac-LKKTETQ fragment lit where the studies confirm it, the full-length thymosin beta-4 substitutions and the dark human-evidence gap left plainly visible, and the FDA 503A status read first; no clinic behind the aurora and nothing here ordered, dispensed, or sold.