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Regeneration

TB-500 FRAG

The active fragment of thymosin beta-4, focused on tissue regeneration, wound healing and new vessel formation.

2 min read 7 sources

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TB-500 FRAG vial with white powder and the black TPD label on a white podium, next to a blue 3D molecule chain in a bright lab
Preclinical only · not approved

Summary

At a glance

Sources checked on 26 Oct 2026

Length of the fragment
7 amino acids

LKKTETQ, the actin-binding site of thymosin beta-44

Length of thymosin beta-4
43 amino acids

the whole body protein the fragment comes from5

Same effect on vessel cells
~50 nM

Fragment and whole thymosin beta-4 acted almost equally strongly in a cell assay3

Human trials on the fragment
0 trials

no real trial on ClinicalTrials.gov, as of 26 Oct 20266

  • TB-500 FRAG is the piece LKKTETQ (amino acids 17 to 23) of thymosin beta-4, a body protein of 43 amino acids. At this site thymosin beta-4 binds the structural protein actin.57
  • In a cell assay the fragment promoted the migration of vessel cells and the sprouting of new vessels almost as strongly as the whole molecule.3
  • In old mice it helped close skin wounds about as well as thymosin beta-4. The whole molecule sped up wound healing in rats by up to 61 percent.42
  • The fragment has not been studied in humans, there are no tolerability data.6
  • No approval is known. Everything here is the state of research, not a recommendation.6
Profile

Updated May 2026

Class
Thymosin beta-4 fragment

regenerative

Use
Subcutaneous

in mg

Half-life
moderate
Status
Preclinical

Tβ4 well studied

Sizes
10 mg

1 size in the shop

Contents 15 sections
  1. At a glance
  2. What is TB-500 FRAG?
  3. How it works
  4. What you need
  5. Reconstitution
  6. Dosing
  7. Injection
  8. What the research shows
  9. Research status
  10. Side effects
  11. Storage
  12. Related compounds
  13. FAQ
  14. Glossary
  15. Sources

What is TB-500 FRAG?

TB-500 FRAG is the active piece of thymosin beta-4 (Tβ4), an endogenous protein strongly involved in tissue regeneration. The fragment is meant to deliver the regenerative core of the effect: better healing, cell migration and new vessel formation.

Comparison

Thymosin beta-4 and its pieces

The whole molecule, its fragments and the blends in the TPD lexicon. Tap a card to open its entry.

Fragment 17 to 23 (LKKTETQ) TB-500 FRAG Actin
Whole thymosin beta-4 TB-500 (Thymosin Beta-4) ActinAc-SDKP Starting piece Ac-SDKP TB-500 FRAG 1-4 (Ac-SDKP) Ac-SDKP Blend with BPC-157 BPC-157 + TB-500 FRAG Blend ActinBPC-157

5

How it works

Thymosin beta-4 acts via actin binding on cell migration, the formation of new blood vessels (angiogenesis) and the dampening of inflammation. The fragment carries the section central to these effects and is therefore used for recovery of tendons, muscles and connective tissue.

Where it acts

Where the fragment acted in studies

Tap a point or a card. All from cell assays and mice.

  1. Blood vessels

    More vessel cell migration and vessel sprouting, almost as strong as with the whole molecule (cell assay)3

    Actin
  2. Skin

    Skin wounds in old mice repaired about as well as with thymosin beta-44

    Actin

Known targets3

Compound PubChem CID 10169788 (LKKTETQ): one described target, The fragment is the actin-binding site of thymosin beta-4. Soluble actin blocked the effect in the cell assay.

Actin (LKKTETQ binding site)
Gene
ACTB
UniProt
P60709
ChEMBL
CHEMBL2062353
Action
The fragment is the actin-binding site of thymosin beta-4. Soluble actin blocked the effect in the cell assay
Glass fibre bundles with branching fine vessels that blue and white molecule chains dock onto
Symbolic image.

What you need

Supplies

2 things, numbered as in the picture

Tick off what you already have. Vial and BAC water are our real shop photos at the same size.

TB-500 FRAG vial and bacteriostatic water at the same size with the black TPD label, next to two U-100 insulin syringes, two alcohol swabs and a sharps container with a blue lid

  1. TB-500 FRAG vial

    The TB-500 FRAG vial (lyophilized powder).

    In the shop

  2. Water and supplies

    Bacteriostatic water, U-100 insulin syringes, alcohol swabs.

    In the shop

Reconstitution

Use the peptide calculator. A 5mg vial with 2ml water gives 2.5mg per ml, 2.5mg is then 100 units on the U-100 syringe. Just add the water to the vial and let it dissolve.

Step by step

Dissolving the powder

Four steps, the same for every vial size.

  1. 1Wipe the cap

    Clean the rubber stopper with an alcohol swab.

  2. 2Add BAC water

    Just add it, it does not matter if it hits the powder directly.

  3. 3Swirl or shake

    Until everything has dissolved, both are fine.

  4. 4Draw up

    With the U-100 insulin syringe.

Less water higher concentration fewer units on the syringe Example: 10 mg + 2 ml = 5 mg/ml

Dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts

Injection

The injection is subcutaneous, into the fat layer under the skin. Common spots are the abdomen (keep about two finger-widths clear of the navel), the front and the inner side of the thigh, or the back of the upper arm.

The short version:

Injection

Where and at what angle

Pick a spot or switch the angle. Subcutaneous means: into the fat layer, not the muscle.

Rotate the spot each time, never the same one twice in a row.

90°More fat under the skin

Rule of thumb: where there is more fat under the skin, insert straight at 90 degrees. In lean people with little fat, 45 degrees, so the needle stays in the fat layer. Simplified diagram.

  1. Clean the spot with an alcohol swab and let it dry

  2. Pinch up a small fold of skin

  3. Insert the needle: at 90 degrees where there is more fat under the skin, at 45 degrees in lean people with little fat

  4. Inject slowly, wait a moment, then withdraw

  5. Put the needle straight into the sharps container

Rotate the site each time so the tissue does not get irritated. Never the same spot twice in a row.

What the research shows

Thymosin beta-4 itself is well described (overview: Crockford, 2010) and accelerated wound healing and new vessel formation in preclinical models (Malinda, 1999). For the isolated fragment in humans the data is thinner, the regenerative mechanism comes from Tβ4 research.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

Skin wounds with whole thymosin beta-42

More than in the saline control group, in percent

Skin closed again, day 42
Whole thymosin beta-4 42%
Skin closed again, day 72
Whole thymosin beta-4 61%
Wound contracted, day 72 at least
Whole thymosin beta-4 11%

Values according to the abstract, measured with the whole molecule, not with the fragment. With the fragment alone a study in old mice showed similar wound healing as with thymosin beta-4, the abstract gives no figures.

Thymosin beta-4 and its active sites5

Length in amino acids

Whole thymosin beta-45
Whole thymosin beta-4 43%
Starting piece with Ac-SDKP5 Cell survival
Whole thymosin beta-4 15%
LKKTETQ (this fragment)5 Vessels, wound healing, cell migration
Whole thymosin beta-4 7%
Ac-SDKP5 Inflammation and scarring curbed
Whole thymosin beta-4 4%

According to the review by Sosne 2010 the effects on vessels, wound healing and cell migration sit in the LKKTETQ section. The anti-inflammatory effect belongs to Ac-SDKP at the start of the molecule, so not to this fragment.

Twisted glass fibre bundle like a tendon in a glass display case on a white plinth
Data come from cell assays and animals. Symbolic image.

Research status

Where the research stands

No real trial on the fragment is listed on ClinicalTrials.gov. Human trials exist only for whole thymosin beta-4, which is a different substance. As of 26 Oct 2026. 6

  1. Preclinical Cell assays and mice
  2. Phase 1 no registered trial
  3. Phase 2 no registered trial
  4. Phase 3 no registered trial
  5. Approval not yet
No approval is known for the fragment.6

So far there is no registered trial in humans. 6

Side effects

  • Generally well tolerated, mainly local reactions at the injection site.
  • Solid long-term human data are missing.
  • As with regenerative factors, a growth-promoting signal is theoretically critical with pre-existing growths.

Storage

Before mixing the powder is robust, normal room temperature (around 20 to 25 degrees) is fine, ideally kept in the dark. After mixing, keep in the fridge (2 to 8 degrees), do not freeze. It stays good there for at least 4 to 6 months with barely any loss of potency, in practice considerably longer. Swirl or shake to mix, both are fine.

Shelf life

How long it keeps

Undissolved (powder) Room temperature, around 20 to 25 degrees, dark

Robust, no fridge needed.

Dissolved (mixed) Fridge, 2 to 8 degrees, do not freeze

At least 4 to 6 months with barely any loss of potency.

  • Keep it dark
  • Dissolved: 2 to 8 degrees
  • Note the mixing date on the vial
Nine vials with white powder and blue caps in the door shelf of a bright fridge
Powder dark at room temperature, once dissolved into the fridge (2 to 8 degrees), do not freeze, stable there for at least 4 to 6 months. Symbolic image.

Related

Related compounds

Same targets, blends with TB-500 FRAG or a different path: all in the TPD lexicon.

TB-500 FRAG
TB-500 (Thymosin Beta-4) The whole molecule the fragment comes from TB-500 FRAG 1-4 (Ac-SDKP) Another piece: Ac-SDKP from the start BPC-157 + TB-500 FRAG Blend Fragment together with BPC-157 BPC + TB Blend BPC-157 with whole TB-500 BPC-157 Another peptide from healing research

FAQ

Common questions about TB-500 FRAG

Short answers, each backed by the sources below.

What exactly is TB-500 FRAG?

The piece LKKTETQ from thymosin beta-4, amino acids 17 to 23. At this site the whole molecule binds the structural protein actin. According to a review this is the part that promotes new vessel growth, wound healing and cell migration.54

Has the fragment been studied in humans?

No. There is no human study on the fragment and no real trial on ClinicalTrials.gov. Human trials exist only for whole thymosin beta-4. No approval is known. The information here is not a recommendation for use.61

What did the cell assay show?

With vessel cells from the umbilical cord and vessel rings from chick embryos the whole molecule and the fragment acted almost equally strongly on cell migration and vessel sprouting at about 50 nM. Pieces without the actin-binding site had no effect. Soluble actin blocked the effect.3

What is known about wound healing?

In 26-month-old mice, whose wounds heal slowly, the fragment promoted healing similarly to whole thymosin beta-4. The whole molecule sped up skin closure in rats by 42 percent on day 4 and by up to 61 percent on day 7.42

How does it differ from TB-500 and TB-500 Frag 1-4?

TB-500 stands for whole thymosin beta-4 with 43 amino acids. TB-500 FRAG is only the section 17 to 23 with the actin-binding site. Frag 1-4 is another piece from the start (Ac-SDKP), to which the review attributes rather an anti-inflammatory and anti-scarring effect.5

Which side effects are known?

There are no solid data because the fragment has not been studied in humans. The regular entry mentions as a theoretical point that a signal for new vessel growth could be unfavourable with existing growths. This is not proven.63

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

Actin
Structural protein that forms the cell's scaffold and is needed for cells to move and migrate.
Angiogenesis
Formation of new blood vessels from existing ones. Important for wound healing, but also for the growth of tumours.
Cell migration
Movement of cells to another place, for example into a wound.
Fragment
A short piece of a larger protein, here seven amino acids from thymosin beta-4.
Lyophilisate
Freeze-dried powder. Without water a peptide keeps much longer.
nM (nanomolar)
Measure of concentration in a lab assay. The smaller the value at which a substance acts, the more potent it is.
Preclinical
Research before use in humans, in cell cultures and animal models.
Subcutaneous
Into the fat layer just under the skin.
Thymosin beta-4
Body protein of 43 amino acids found in almost all cells that binds the structural protein actin.

Evidence

Sources

Show all 7 sourcesHide sources 4 Studies1 Trial registry2 Database checked 26 Oct 2026

Studies

  1. Thymosin beta-4 speeds up wound healing (rats)

    Malinda et al., Journal of Investigative Dermatology, 1999

    DOI 10.1046/j.1523-1747.1999.00708.x PMID 10469335
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  2. The actin-binding site of thymosin beta-4 promotes new vessel growth

    Philp et al., The FASEB Journal, 2003

    DOI 10.1096/fj.03-0121fje PMID 14500546
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Thymosin beta-4 and LKKTETQ in wounds of diabetic and old mice

    Philp et al., Wound Repair and Regeneration, 2003

    DOI 10.1046/j.1524-475x.2003.11105.x PMID 12581423
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Review of the active sites of thymosin beta-4

    Sosne et al., The FASEB Journal, 2010

    DOI 10.1096/fj.09-142307 PMID 20179146
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Search for the fragment on ClinicalTrials.gov (0 results)

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. Review of structure, function and clinical potential of thymosin beta-4 (PubMed record)

    Crockford et al., Annals of the New York Academy of Sciences, 2010 (DOI 10.1111/j.1749-6632.2010.05492.x)

    PMID 20536467
    Checked 26 Oct 2026 via PubMed, doi.org, Crossref
  2. Structure of LKKTETQ in PubChem

    PubChem, U.S. National Library of Medicine (CID 10169788)

    Checked 26 Oct 2026 via PubChem

In the shop

TB-500 FRAG in the catalog

Sizes, prices and shipping times are on the product page.

To the product