BPC-157 vs TB-500: structure, mechanism and research

How are BPC-157 and TB-500 structurally different?

These two peptides are often discussed together, but they have no structural relationship. BPC-157 is a synthetic 15-residue peptide, GEPPPGKPADDAGLV, corresponding to a partial sequence of body protection compound, a protein isolated from human gastric juice. The 2003 tendon paper describes it as a stable gastric pentadecapeptide, and much of its literature concerns gastric, tendon and vascular models.

TB-500 belongs to a different family. Thymosin β4 is a naturally occurring 43-residue peptide, and its residues 17 to 23, LKKTETQ, form the region proposed to bind actin. In the analytical literature, TB-500 means a synthetic copy of that seven-residue region with an acetylated N-terminus, Ac-LKKTETQ. An equine doping-control study describes a veterinary preparation sold as TB-500 whose key ingredient is exactly that fragment.

The identity table above is generated from each product's content file and certificate, so we do not repeat the figures here, with one exception that matters for anyone comparing the two.

Which molecule does our TB-500 certificate identify?

The certificate for our TB-500 lot, ABL-TB5-2602, issued by Freedom Diagnostics, prints the CAS number, formula and molecular weight of full-length thymosin β4 (about 4963 g/mol), not those of the seven-residue fragment (about 889 g/mol). The identity table follows the certificate. The certificate lists identity by mass (LC-MS) but prints no observed mass, so it does not show which of the two molecules the laboratory actually measured. Until the laboratory confirms the observed mass, the paperwork does not settle what is in the vial.

That matters for reading the literature, because most published thymosin β4 work used the full-length peptide, and findings for one should not be assumed to apply to the other. Researchers who need to tell them apart should confirm identity by mass spectrometry. Our HPLC vs mass spec: what each test proves guide explains why a purity figure alone cannot answer that question, and our testing page lists what each certificate reports.

How are BPC-157 and TB-500 proposed to work?

They are proposed to work in unrelated ways: BPC-157 through signalling observed in particular cell types, thymosin β4 mainly through actin binding. For BPC-157, the proposed pathways come from individual cell and rodent models. In cultured rat tendon fibroblasts, it increased migration and spreading alongside increased phosphorylation of FAK and paxillin, and a later study in the same cell type reported up-regulation of growth hormone receptor. In human vascular endothelial cells, Hsieh and colleagues reported increased VEGFR2 expression and internalisation with VEGFR2-Akt-eNOS signalling, effects blocked by the endocytosis inhibitor dynasore. A Zagreb review also relates the peptide to the nitric oxide system in rodent studies.

For thymosin β4, the best-characterised activity is structural. Safer and colleagues showed that it is identical to Fx, the peptide that holds much of the unpolymerised actin in platelets, and that it binds actin monomers in a 1:1 complex and inhibits their polymerisation. Later work proposed that it stimulates cell migration, and in mouse cardiomyocytes that it forms a complex with PINCH and integrin-linked kinase, activating Akt.

The two sets of proposals do not describe a shared mechanism. BPC-157's are signalling observations in particular cell types; thymosin β4's centre on actin binding, a property localised to the very fragment that the name TB-500 usually refers to.

What models have BPC-157 and TB-500 been studied in?

Both have been studied only in cell and animal models, by different groups and in different tissues. BPC-157 has been studied mostly in rodents: rat Achilles tendon transection, where Staresinic and colleagues reported higher load to failure and more collagen formation over 14 days; rat hind-limb ischaemia, where blood flow recovered faster with more vessels; and rodent gastric and nitric oxide models. Cell work includes rat tendon explants and fibroblasts, human endothelial cells and the chick chorioallantoic membrane assay.

Thymosin β4 has been studied in purified-protein actin experiments, keratinocyte migration assays, rat full-thickness wounds, and mouse cardiac models. Work on the fragment itself is thin. Philp and colleagues tested a synthetic LKKTETQ peptide in aged mice and reported dermal repair comparable to the parent molecule; the equine study by Ho and colleagues developed a method to detect Ac-LKKTETQ and its metabolites in urine and plasma, which is an analytical study, not a test of biological activity.

Both compounds sit in our Tissue Repair research area, which is the only sense in which their literatures overlap: both have been examined in injury-repair models, by different groups, in different tissues.

How does the evidence for BPC-157 and TB-500 differ?

Both literatures are preclinical. The difference is in who produced them. A large share of the published BPC-157 work comes from one group at the University of Zagreb, including the 2003 tendon study, and a 2019 critical review by Gwyer, Wragg and Wilson noted that most studies used small rodent models and that only a handful of research groups have studied the peptide in depth. The tendon-cell and vascular studies from Chang Gung University in Taiwan are among the few independent lines of work.

Thymosin β4 has a broader and older base, from several laboratories, beginning with protein biochemistry in 1991 and extending to wound and cardiac models. But that base is mostly about the 43-residue peptide. For the seven-residue fragment, the evidence is a single aged-mouse wound study and analytical chemistry.

What does research on BPC-157 and TB-500 not show?

Neither body of work establishes a mechanism: the reviews for both describe the pathways as proposals from individual models. Neither has been confirmed in human clinical studies. There is no published study comparing BPC-157 with thymosin β4 or its fragment head to head, so no ranking of the two is possible from the literature, and we do not offer one.

Our GLOW blend contains both, together with GHK-Cu. We know of no published study of that combination, and nothing on this page should be read as evidence that the compounds act together.

If you are comparing lots from any supplier, read each certificate for what it actually measured. Our guide on How to read a peptide certificate of analysis covers that in detail, and Red flags in a peptide COA: spotting a fake lists the problems to look for.

References

1. Staresinic M, Sebecic B, et al. (2003). Gastric pentadecapeptide BPC 157 accelerates healing of transected rat Achilles tendon and in vitro stimulates tendocytes growth. J Orthop Res. [RODENT] PubMed record for reference 1, Staresinic 2003
2. Hsieh MJ, Liu HT, et al. (2017). Therapeutic potential of pro-angiogenic BPC157 is associated with VEGFR2 activation and up-regulation. J Mol Med (Berl). [RODENT] PubMed record for reference 2, Hsieh 2017
3. Gwyer D, Wragg NM, Wilson SL (2019). Gastric pentadecapeptide body protection compound BPC 157 and its role in accelerating musculoskeletal soft tissue healing. Cell Tissue Res. [REVIEW] PubMed record for reference 3, Gwyer 2019
4. Safer D, Elzinga M, Nachmias VT (1991). Thymosin beta 4 and Fx, an actin-sequestering peptide, are indistinguishable. J Biol Chem. [IN VITRO] PubMed record for reference 4, Safer 1991
5. Philp D, Badamchian M, Scheremeta B, et al. (2003). 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. [RODENT] PubMed record for reference 5, Philp 2003
6. Ho EN, Kwok WH, Lau MY, et al. (2012). 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. [OTHER ANIMAL] PubMed record for reference 6, Ho 2012
7. Sikiric P, Seiwerth S, et al. (2014). Stable gastric pentadecapeptide BPC 157-NO-system relation. Curr Pharm Des. [REVIEW] PubMed record for reference 7, Sikiric 2014
8. Chang CH, Tsai WC, et al. (2011). The promoting effect of pentadecapeptide BPC 157 on tendon healing involves tendon outgrowth, cell survival, and cell migration. J Appl Physiol (1985). [IN VITRO] PubMed record for reference 8, Chang 2011
9. Chang CH, Tsai WC, et al. (2014). Pentadecapeptide BPC 157 enhances the growth hormone receptor expression in tendon fibroblasts. Molecules. [IN VITRO] PubMed record for reference 9, Chang 2014
10. Bock-Marquette I, Saxena A, White MD, et al. (2004). Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. [RODENT] PubMed record for reference 10, Bock-Marquette 2004
11. Malinda KM, Sidhu GS, Mani H, et al. (1999). Thymosin beta4 accelerates wound healing. J Invest Dermatol. [RODENT] PubMed record for reference 11, Malinda 1999
12. Goldstein AL, Hannappel E, Sosne G, et al. (2012). Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opin Biol Ther. [REVIEW] PubMed record for reference 12, Goldstein 2012

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