TB-500 vs Thymosin Beta-4: A Research Guide

“TB-500” and “thymosin beta-4” are used almost interchangeably online, but they are not always the same molecule. This guide covers what thymosin beta-4 is, what the actin-binding fragment called TB-500 is, and what the research on each has found.

Thymosin beta-4 vs. TB-500

Thymosin beta-4 (Tβ4) is a naturally occurring 43-amino-acid protein of about 4.9 kDa, found in most cells. Its best-known job is binding G-actin, the single-unit form of actin. By sequestering G-actin, Tβ4 regulates how quickly cells can build actin filaments, which in turn affects how cells move and change shape [1].

TB-500 is the name used for a synthetic research peptide built around the actin-binding region of Tβ4. A 2012 analytical study of a product sold as TB-500 identified the N-terminally acetylated 17–23 fragment of Tβ4 (Ac-LKKTETQ) [2]. The seven-amino-acid sequence LKKTETQ is the core of Tβ4’s actin-binding domain.

Because the name is used loosely across the market, the only reliable way to know what a vial contains is its analytical data. Always check the mass-spec identity and HPLC purity on the Certificate of Analysis.

What has the research looked at?

Cell migration and angiogenesis

Tβ4 has been studied heavily for its effects on cell movement. In a 1997 FASEB Journal study, Tβ4 acted as a chemoattractant for human umbilical vein endothelial cells, increasing their migration four- to six-fold over media alone. It also sped closure of scratch wounds in cell monolayers and stimulated cell migration in an implanted-gel model. The authors called this the first direct evidence that Tβ4 promotes angiogenesis by stimulating endothelial cell migration [3].

Dermal wound models

A 2003 study in Wound Repair and Regeneration tested Tβ4 in full-thickness skin wounds in diabetic (db/db) mice and in 26-month-old mice, two models where healing is delayed. Tβ4 increased wound contracture and collagen deposition. A synthetic seven-amino-acid peptide containing the actin-binding sequence LKKTETQ was also active in these models [4]. This is the main reason researchers study the fragment on its own.

Cardiac models

A 2004 paper in Nature reported that Tβ4 promoted migration and survival of heart-muscle cells in culture. It formed a complex with PINCH and integrin-linked kinase (ILK) that activated the survival kinase Akt. In mice with a ligated coronary artery, Tβ4 treatment improved early cell survival and cardiac function [5].

Where the evidence stops

Nearly all of these findings come from cell culture and animal models. Many were run with full-length Tβ4, and those results cannot be assumed to transfer to short fragments. TB-500 is not an FDA-approved drug.

Laboratory handling

• Store lyophilized material cold, dry and protected from light, following the label and COA.
• Confirm which molecule you have (full-length Tβ4 or the 17–23 fragment) from the mass-spec data before designing an experiment.
• Log lot numbers so results trace back to a specific batch.

FAQ

Is TB-500 the same as BPC-157?
No. They are unrelated peptides, though they are often studied side by side in tissue-repair research. See our BPC-157 research guide.

Is TB-500 approved for human use?
No. Ares Labs sells TB-500 for laboratory research only.

View TB-500 research vials and the current COA →

References

1. Hannappel E. beta-Thymosins. Ann N Y Acad Sci. 2007. PMID 17468232
2. Esposito S, Deventer K, Goeman J, et al. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500. Drug Test Anal. 2012;4(9):733-738. PMID 22962027
3. Malinda KM, Goldstein AL, Kleinman HK. Thymosin beta 4 stimulates directional migration of human umbilical vein endothelial cells. FASEB J. 1997;11(6):474-481. PMID 9194528
4. Philp D, Badamchian M, Scheremeta B, et al. Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice. Wound Repair Regen. 2003;11(1):19-24. PMID 12581423
5. 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. PMID 15565145

For laboratory research use only. Not for human or animal consumption. This article summarizes published research for reference. It is not medical advice and makes no claim that any product treats, cures or prevents any condition.