Compound hub · TB-500
What does TB-500 do? What published studies found
Published research shows little about what TB-500 does, because the FDA's briefing document (memo dated 15 May 2026) reports identifying no human study of it. In aged mice with skin wounds (number not stated in the FDA summary), the untagged fragment LKKTETQ and thymosin beta-4 each increased epidermal closure and collagen content on day 7, an animal result without a dose-response assessment that does not describe TB-500 or people (Philp et al., 2003, as summarised by the FDA). In cultured fibroblasts, TB-500 itself did not close scratch wounds significantly more than vehicle after 8 hours, a cell result that does not establish an effect in a living animal or person (Rahaman et al., 2024, as summarised by the FDA).
01In the bodyContents
When you scrape a knee, cells at the edge of the wound crawl across the gap, and new fibres and blood vessels follow. That crawling depends on protein threads inside each cell, and the molecules that manage those threads are what the TB-500 papers are about.
This page is part of the TB-500 hub. It sorts the published findings by how far they travelled: cells first, then animals, then people. Each answer is a study result, not a promise. For what the compound is, read the TB-500 explainer, and for its safety record, the side-effects page.
Key facts
| Compound | TB-500, Ac-LKKTETQ |
|---|---|
| Human studies of TB-500 | None identified in the FDA briefing document (memo dated 15 May 2026) |
| Registered TB-500 trial | NCT07487363, Phase 1/2, 80 people planned, recruiting, no results posted on 14 October 2026 |
| Mouse wound study of the untagged fragment | Aged mice, number not stated in the FDA summary; day 7 (Philp et al., 2003) |
| Cell study of TB-500 itself | Cultured fibroblasts; 8-hour wound closure not significantly different from vehicle; cell test only, no animal or human effect established (Rahaman et al., 2024) |
| Registered thymosin beta-4 trials | 17 records besides the TB-500 trial in a ClinicalTrials.gov search for 'thymosin beta 4', read 14 October 2026 |
| Largest thymosin beta-4 trial record | ARISE-3, 700 people, dry eye (NCT03937882) |
| Muscle study in mice | Dystrophin-deficient mice, number not stated in the abstract (Spurney et al., 2010) |
| Obesity-model study in mice | Mice, number not stated in the abstract (Gonzalez-Franquesa et al., 2021) |
Evidence limits
What does research show TB-500 does in the body?
Published research shows little about what TB-500 does in the body, because the FDA's briefing document (memo dated 15 May 2026) reports identifying no human study of it. A 2010 review of laboratory work reports that thymosin beta-4 binds actin, the protein that builds the cell's internal threads, through a central region that includes the LKKTETQ sequence (Sosne et al., FASEB Journal, 2010). In aged mice with skin wounds (number not stated in the FDA summary), thymosin beta-4 and the untagged fragment LKKTETQ each increased epidermal closure and collagen content on day 7, an animal result without a dose-response assessment that does not describe TB-500 (Philp et al., 2003, as summarised by the FDA). In cultured fibroblasts, TB-500 itself did not close scratch wounds significantly more than vehicle after 8 hours, while a shorter breakdown piece, Ac-LKKTE, produced a small significant closure (number of cultures not stated in the FDA summary), a cell result that does not show an effect in a living body (Rahaman et al., Journal of Chromatography B, 2024, as summarised by the FDA).
The FDA's briefing document (memo dated 15 May 2026) is blunt: nonclinical pharmacological evidence is 'currently lacking' to support the potential for TB-500 to promote wound healing, and it 'remains unknown' whether either TB-500 form has wound-healing properties in vivo. The FDA adds that acetylation, the added chemical tag, changes how a peptide behaves, so findings on the untagged fragment cannot be directly extrapolated to TB-500.
That leaves a gap between the molecule's reputation and its record. The TB-500 identity page shows which sequence each paper tested.
What have studies of TB-500 found?
Studies of TB-500 itself in the sources opened for this page concern chemistry, animals and cells rather than any health outcome in people. Esposito et al. detected Ac-LKKTETQ in a TB-500 product and made it in the laboratory, a chemistry result that says nothing about effects in animals or people (Drug Testing and Analysis, 2012). Ho et al. found TB-500 and its breakdown products in horse plasma and urine after horses were treated with a veterinary product, a result in horses (number not stated in the abstract) that is not a human finding (Journal of Chromatography A, 2012). Rahaman et al. measured breakdown products in rat urine and in human serum and found no cytotoxicity in the fibroblasts tested, a laboratory and rat result (number of rats not stated in the abstract) that is not a human safety finding (Journal of Chromatography B, 2024). None of these three papers reports whether TB-500 changes a health outcome in any animal or person.
Full-length thymosin beta-4 has far more data. A 2015 narrative review reports tissue-repair studies in animals and lists trials planned or under way for eye injuries, skin wounds, heart damage after a heart attack and brain repair; it is a review, not a trial, and it concerns the full-length protein (Goldstein and Kleinman, Expert Opinion on Biological Therapy, 2015, abstract checked).
The FDA notes that websites often use the names TB-500 and thymosin beta-4 interchangeably, although the two are not the same substance. A finding quoted for one may belong to the other. The TB-500 research guide keeps the two apart.
What is TB-500 used for in the published literature?
In the papers opened for this page, TB-500 appears mainly as a substance to detect, not as a studied treatment. The two 2012 papers describe a veterinary product and laboratory methods for finding it in horse samples for anti-doping control (Ho et al., 2012; Esposito et al., 2012). The FDA's briefing document (memo dated 15 May 2026) reports that TB-500 is marketed online for a wide range of conditions and that the FDA identified no human study behind those claims. The TGA says unapproved peptide products have not been evaluated for safety, quality or effectiveness (TGA advisory, 13 April 2026).
A 'used for' answer therefore has two parts: what researchers did with the compound in the papers opened, which is detect it, and what sellers say about it, which the FDA found no human study to support. The catalogue lists TB-500 reference material as a laboratory product, and research material is not a medicine.
The TGA advisory of 13 April 2026 names TB-500 among unapproved peptide products that are promoted online with a range of claims.
Has TB-500 been studied for muscle growth?
No study of TB-500 that measured muscle growth appears in the sources opened for this page. For full-length thymosin beta-4, a six-month study of dystrophin-deficient mdx mice, a model of Duchenne muscular dystrophy, reported more regenerating muscle fibres but no significant improvement in grip strength, heart function or fibrosis, a mouse result (number not stated in the abstract) for a different molecule that does not describe people (Spurney et al., PLoS One, 2010). In a second mouse study (number not stated in the abstract), thymosin beta-4 treatment did not enhance muscle regeneration, a result for a different molecule that does not describe people (Gonzalez-Franquesa et al., American Journal of Physiology-Cell Physiology, 2021). Neither study used TB-500, and neither measured muscle size in people.
In contracting mouse muscle cells in a dish, thymosin beta-4 was the most upregulated secreted protein, a cell finding about the body's own protein that does not establish an effect of TB-500 or a result in people (Gonzalez-Franquesa et al., 2021).
A 2026 scoping review concluded that claims for such peptides in musculoskeletal recovery and performance 'remain unsubstantiated by current human trials'; it is a review of publications, and only its abstract was checked (Tewari et al., The American Journal of Sports Medicine, 2026). The World Anti-Doping Agency 2026 list names thymosin-ß4 and TB-500 under S2.3, a class that also covers growth factors affecting muscle, tendon or ligament protein synthesis; the listing is a rule, not a finding.
Has TB-500 been studied for weight loss?
No study of TB-500 that measured weight loss appears in the sources opened for this page. The nearest evidence is a 2021 mouse study (number not stated in the abstract) in which full-length thymosin beta-4 treatment did not ameliorate the metabolic disruptions associated with diet-induced obesity, a mouse result for a different molecule that does not describe people (Gonzalez-Franquesa et al., 2021). The TGA says unapproved peptide products are promoted online with a range of claims and that it has not assessed their safety, quality or effectiveness (advisory, 13 April 2026). In a PubMed search on 14 October 2026 for thymosin beta 4 with adipose, obesity or body-weight terms, the titles of the first eight results did not describe a human weight trial; this is a title screen, not a systematic search, and it does not show that no such trial exists.
The mouse study used full-length thymosin beta-4, not TB-500. In laboratory tests in the same work (number not stated in the abstract), the protein increased bone-cell growth and nerve-cell outgrowth, results in cells that the authors link to its anti-doping classification as a prohibited growth factor and that do not describe people; the metabolic result in mice was negative (Gonzalez-Franquesa et al., 2021).
What did human trials of thymosin beta-4 find in wound healing?
Three registered Phase 2 trials of full-length thymosin beta-4 in skin wounds are summarised here, all small and none with TB-500. In a 72-person pressure-ulcer trial (54 treated, 18 placebo), the trial record lists 8 of 54 treated people (15%) and 3 of 18 on placebo (17%) as healed at day 84, counts with no significance test in the record (NCT00382174). In a 30-person epidermolysis bullosa trial that ended early for lack of patients and expired study drug, the record lists 8 of 22 treated and 5 of 8 placebo participants as healed by day 56, with a reported p-value above 0.05 (NCT00311766). In a venous leg ulcer trial record of 72 people (55 treated, 17 placebo; the paper reports 73 randomised), 12 of 55 treated and 4 of 17 placebo participants had wound closure without drainage at day 84, and the record's result lists no test of treatment against placebo (NCT00832091; Guarnera et al., Annals of the New York Academy of Sciences, 2010).
The venous ulcer trial record and its paper differ on size, 72 participants on the record and 73 randomised in the paper, and this page reports both as found without reconciling them; the paper's abstract describes efficacy as a possibility, not a finding (NCT00832091; Guarnera et al., 2010).
Eye trials reported both signs and misses. In a single-centre Phase 2 dry eye trial of 72 people, neither primary endpoint reached significance, though some secondary measures did, such as a 27% lower discomfort score than placebo in the controlled-environment challenge on day 28, and the trial tested no TB-500 (Sosne and Ousler, Clinical Ophthalmology, 2015). In a nine-patient Phase 2 trial in severe dry eye, the abstract reports 35.1% less ocular discomfort than vehicle at day 56 in 12 treated and 6 vehicle eyes, in a small trial with no TB-500 (Sosne et al., Cornea, 2015).
In nine patients with chronic neurotrophic corneal defects, reported as compassionate-use cases without a control group, the authors report that six with geographic defects showed 'dramatic healing' and that stromal thinning was observed in one patient, with three patients with punctate defects showing no demonstrable change (Dunn et al., Annals of the New York Academy of Sciences, 2010). None of these studies tested TB-500.
How many clinical trials of TB-500 and thymosin beta-4 are registered?
ClinicalTrials.gov returned 18 records for the search term thymosin beta 4 on 14 October 2026, and searches for TB-500 and for TB500 on the same date returned one record each, the same TB-500 trial. NCT07487363 is a Phase 1/2 study of 80 people planned with stable atherosclerotic cardiovascular disease, recruiting since 5 February 2026 at a hospital in Shenzhen, China. The other 17 records cover full-length thymosin beta-4: 11 completed, 2 terminated, 2 withdrawn, 1 recruiting and 1 not yet recruiting, across conditions that include dry eye, skin ulcers, heart attack, neurotrophic keratopathy and healthy volunteers.
A registry entry shows that a trial exists, not that it produced results. Two records were withdrawn before enrolling anyone; NCT00743769, a Phase 1 safety study in healthy volunteers, gives 'study never initiated due to contract manufacturing issues' as its reason.
The published papers sit in PubMed. A single 2010 journal volume carried several of them, including the Guarnera and Dunn papers cited on this page.
What did heart studies of thymosin beta-4 find?
In mice (number not stated in the abstract), thymosin beta-4 treatment after coronary artery ligation was followed by greater early heart-cell survival and improved heart function, a mouse result that does not show an effect in people (Bock-Marquette et al., Nature, 2004). In a 2025 randomised, double-blind, placebo-controlled trial of 96 people after a ST-segment elevation heart attack, recombinant thymosin beta-4 was followed by a reduced infarct area at 90 days in a 43-person subgroup, but the overall difference across all 96 was not statistically significant (Zhang et al., Cardiovascular Research, 2025). Both findings are for full-length thymosin beta-4, and neither concerns TB-500.
The trial product is a recombinant protein and the mouse work used the natural sequence, so the two are different forms. The trial authors call for further rigorous randomised studies (Zhang et al., 2025).
Comparison
Human wound-healing and eye studies of full-length thymosin beta-4, with the result each reported, its main limit and its source. None tested TB-500. Rows are not pooled.
| Study | Who | Result, limit and source |
|---|---|---|
| Venous leg ulcers, Phase 2 | 72 people on the trial record (55 treated, 17 placebo); the paper reports 73 randomised; wound outcome assessed through day 84 | In 72 people with venous leg ulcers on the trial record (the paper reports 73 randomised), the record lists closed wounds without drainage at day 84 in 12 of 55 treated and 4 of 17 placebo participants, with no superiority test in the record's result; small trial with similar proportions in both groups, and the authors' abstract describes efficacy as a possibility (Guarnera et al., 2010; NCT00832091) |
| Pressure ulcers, Phase 2 | 72 people (54 treated, 18 placebo); wound outcome assessed through day 84 | In 72 people with pressure ulcers, the trial record lists 8 of 54 treated and 3 of 18 placebo participants as healed at day 84; counts only, with no significance test read from the record and no paper cited (NCT00382174) |
| Epidermolysis bullosa, Phase 2 | 30 people (22 treated, 8 placebo); wound outcome at day 56; ended early | In 30 people with epidermolysis bullosa, the trial record lists 8 of 22 treated and 5 of 8 placebo participants as healed by day 56, with a reported p-value above 0.05; ended early for lack of patients and expired study drug (NCT00311766) |
| Neurotrophic corneal defects | 9 people; 30-day follow-up | In 9 people with chronic neurotrophic corneal defects, six patients with geographic defects showed 'dramatic healing' and stromal thinning was observed in one; no control group, compassionate-use cases (Dunn et al., 2010) |
| Dry eye, Phase 2 | 72 people; 32-day study | In 72 people with dry eye, neither primary endpoint was significant; the discomfort score was 27% lower than placebo in the controlled-environment challenge on day 28; single centre, and the significant result was a secondary endpoint (Sosne and Ousler, 2015) |
| Severe dry eye, Phase 2 | 9 people with severe dry eye; 56 days in total, including 28 days of follow-up | In 9 people with severe dry eye, at day 56, 35.1% less ocular discomfort and 59.1% less total corneal fluorescein staining than vehicle, in 12 treated and 6 vehicle eyes; nine people only (Sosne et al., 2015) |
FAQ
Has TB-500 been shown to affect muscle growth in studies?
No study of TB-500 that measured muscle growth appears in the sources opened for this page. In dystrophin-deficient mice (number not stated in the abstract), full-length thymosin beta-4 increased regenerating fibres but not strength, a mouse result for a different molecule that does not establish a human result (Spurney et al., 2010). In a second mouse study (number not stated in the abstract), thymosin beta-4 did not enhance muscle regeneration, also a mouse result for a different molecule that does not establish a human result (Gonzalez-Franquesa et al., 2021).
Do mouse wound studies show what TB-500 does in people?
No. The FDA says the 2003 mouse study lacked a dose-response assessment and used the untagged fragment, whose profile cannot be directly extrapolated to the acetylated TB-500 (briefing document, memo dated 15 May 2026). An animal result is not a human result.
What is the registered TB-500 trial measuring?
NCT07487363 lists adverse events as its primary outcomes and four secondary measures: brachial artery flow-mediated dilation, high-sensitivity C-reactive protein, NT-proBNP and carotid-femoral pulse wave velocity. The record's outcome time frames run from 28 days to 12 weeks, and it showed no results on 14 October 2026.
What do TB-500 peptides do to the body according to the FDA?
The FDA's briefing document (memo dated 15 May 2026) states that it found no information in which TB-500 was given to patients to treat any condition. In the same briefing document (15 May 2026), the FDA summarises Ho et al. (2012) as reporting that TB-500 reached the plasma of treated horses (number not stated in the FDA summary) and was broken into smaller peptides, a horse result that does not describe people. The FDA's briefing document of 15 May 2026 also summarises Rahaman et al. (2024) as reporting broken-down peptides in the urine of treated rats (number not stated in the FDA summary) and one fibroblast study (number of cultures not stated) in which TB-500 did not significantly close scratch wounds, animal and cell results that do not establish a result in people.
More in this hub
Citations
15 sourcesSosne G, Qiu P, Goldstein AL, Wheater M. FASEB Journal. 2010;24(7):2144-2151.
doi:10.1096/fj.09-142307Philp D et al. Wound Repair and Regeneration. 2003;11(1):19-24.
doi:10.1046/j.1524-475x.2003.11105.xRahaman KA et al. Journal of Chromatography B. 2024;1235:124033.
doi:10.1016/j.jchromb.2024.124033Esposito S et al. Drug Testing and Analysis. 2012;4(9):733-738.
doi:10.1002/dta.1402Ho EN et al. Journal of Chromatography A. 2012;1265:57-69.
doi:10.1016/j.chroma.2012.09.043Goldstein AL, Kleinman HK. Expert Opinion on Biological Therapy. 2015;15(Suppl 1):S139-S145.
doi:10.1517/14712598.2015.1011617Spurney CF et al. PLoS One. 2010;5(1):e8976.
doi:10.1371/journal.pone.0008976Gonzalez-Franquesa A et al. American Journal of Physiology-Cell Physiology. 2021;321(5):C770-C778.
doi:10.1152/ajpcell.00263.2021Tewari K et al. The American Journal of Sports Medicine. 2026, online 11 August.
doi:10.1177/03635465261464420Guarnera G, De Rosa A, Camerini R. Annals of the New York Academy of Sciences. 2010;1194:207-212.
doi:10.1111/j.1749-6632.2010.05490.xSosne G, Ousler GW. Clinical Ophthalmology. 2015;9:877-884.
doi:10.2147/OPTH.S80954Sosne G, Dunn SP, Kim C. Cornea. 2015;34(5):491-496.
doi:10.1097/ICO.0000000000000379Dunn SP et al. Annals of the New York Academy of Sciences. 2010;1194:199-206.
doi:10.1111/j.1749-6632.2010.05471.xBock-Marquette I et al. Nature. 2004;432:466-472.
doi:10.1038/nature03000Zhang Y et al. Cardiovascular Research. 2025;121:2747-2758.
doi:10.1093/cvr/cvaf223
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TB-500 reference materialResearch use only — not for human or animal use.
Read the TB-500 research guideForm Laboratories supplies research-use-only reference material. This article is an educational summary of published third-party literature. It is not medical advice, not a use instruction, and research material is not for human or animal use.