Update — August 17, 2026
FDA reviewers flagged a fragment-vs-full-protein gap in the TB-500 literature.
In its review ahead of the July 23–24, 2026 Pharmacy Compounding Advisory Committee meeting, FDA staff noted a specific gap in the TB-500 evidence base: the wound-healing studies submitted in support of the substance were conducted using the full-length thymosin beta-4 protein rather than the TB-500 fragment itself, and reviewers identified no human study in which TB-500 had been administered. This distinction between the parent protein and the shorter fragment is a recurring point of confusion in the published literature and is worth noting when evaluating any citation attributed to TB-500.
The committee subsequently voted 8–6 with one abstention to recommend TB-500 for inclusion on the Section 503A Bulk Drug Substances List. That recommendation is non-binding, FDA has not issued a final determination, and it does not constitute approval or any finding of safety or efficacy.
Evidence & Research Status
Educational overview of a compound studied in tissue-repair research. Everything here reflects the published literature — largely preclinical — and is for research and educational purposes only. Not…
Evidence Level reflects the general state of published research for this compound category and is not a claim about the safety, efficacy, or approval status of any product sold on this site. All compounds are offered strictly for research use.
By Charles Fowler, Founder of Portal to Wellness · Last reviewed: June 2026 · ~6 min read
Educational overview of a compound studied in tissue-repair research. Everything here reflects the published literature — largely preclinical — and is for research and educational purposes only. Not medical advice, not a dosing instruction, and not a description of use in humans.
TB-500 is one of the two best-known names in recovery research, usually mentioned in the same breath as BPC-157. This is the focused look at what it actually is and what the science explores. For how it fits the broader picture, see our Recovery & Repair Research Compounds guide.
Key Takeaways
- TB-500 is studied for its role in actin regulation and cell migration during tissue repair.
- Its proposed mechanism centers on promoting cell movement to injury sites.
- Research has explored its use across multiple tissue-repair contexts.
- It’s frequently studied in combination with BPC-157 based on complementary proposed mechanisms.
What TB-500 is
TB-500 is a synthetic peptide based on Thymosin Beta-4 (Tβ4), a naturally occurring 43–amino-acid protein. Specifically it centers on Tβ4’s actin-binding domain (the sequence LKKTETQ). Thymosin Beta-4 is one of the most abundant actin-regulating proteins in cells, which is the key to understanding what researchers study it for.
How it works — actin and cell migration
Tβ4 is an actin-sequestering peptide: it binds actin and holds it in a polymerization-incompetent state until cellular signals call for it. Actin is the protein that drives cell movement, so by regulating the actin pool, Tβ4 is studied for its role in cell migration — helping cells move toward sites of injury. In research models this links to faster re-epithelialization, increased collagen deposition, and angiogenesis (new blood-vessel formation).[1]
What the research explores
Beyond general wound-healing models, Tβ4’s most distinctive research area is cardiac repair: a landmark mouse study found Tβ4 could activate cardiac progenitor cells and support cardiomyocyte survival after induced injury — a regenerative-biology angle that sets it apart from other recovery peptides.[2] It’s also studied for anti-inflammatory and anti-fibrotic signaling. As always, much of this is preclinical.
Why it’s paired with BPC-157
BPC-157 and TB-500 are studied for overlapping but distinct steps of repair — BPC-157 more for structural tissue, TB-500 for cell migration and signaling — which is why they’re the classic research pairing. We break the combination down in BPC-157 and TB-500: Two Mechanisms Compared. Available research-use-only as TB-500 (10mg) or in the BPC-157 + TB-500 blend. If COAs are new to you, read How to Read a Peptide COA.
Frequently asked questions
What is TB-500?
A synthetic peptide based on the actin-binding region of Thymosin Beta-4, studied in research for cell migration, angiogenesis, and tissue repair.
How is TB-500 different from BPC-157?
In the literature TB-500 is studied more for cell migration/signaling and BPC-157 for structural tissue repair; they’re often researched together.
Is TB-500 approved for human use?
No — it’s sold for laboratory and research use only, and much of the data is preclinical. It is also banned in competitive sport.
Related reading
Recovery & Repair guide · BPC-157 Deep Dive · BPC-157 and TB-500: Two Mechanisms Compared
About the author
Charles Fowler is the founder and researcher behind Portal to Wellness. After a career in management consulting, he spent the past two years immersed in the wellness and research-compound space — sourcing products, vetting suppliers, and reading the primary literature daily. He isn’t a physician or a scientist, and he’ll tell you so.
How we research our content
Our Research Library articles are written from peer-reviewed scientific literature and reputable references, and we date every article. We don’t make therapeutic, dosing, or “cure” claims, and we flag where the science is preclinical or unsettled.
References
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin beta-4: actin-sequestering protein moonlights to repair injured tissues. Trends Mol Med. https://pubmed.ncbi.nlm.nih.gov/16002257/
- Bock-Marquette I, et al. Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature. https://pubmed.ncbi.nlm.nih.gov/15457259/
All products sold on this website are intended for research and identification purposes only. They are not intended for human dosing, injection, ingestion, or veterinary use. Must be 18 or older to purchase. This content is educational and is not medical advice.
📚 Part of our Recovery & Repair research guide.
TB-500 — Research-Grade, Research Use Only
Amounts used in the published research
Human trials — full-length Tβ4 only
| Study | Amount | Route | Schedule | n |
|---|---|---|---|---|
| Ruff 2010, healthy volunteers | 42, 140, 420, 1260 mg | IV | Single dose, then same dose daily for 14 days | 40 |
| Wang 2021, recombinant hTβ4 Phase 1a | 0.05 – 25 µg/kg | IV push | Single dose, 28-day observation | 54 |
| Wang 2021, Phase 1b | 0.5, 2.0, 5.0 µg/kg | IV | Once daily for 10 days | 30 |
| RGN-259 dry eye / neurotrophic keratopathy | 0.1% solution | Eye drops | Typically 2–4× daily, 14–28 days | up to 700 |
| RGN-137 chronic wounds | 0.01–0.1% gel | Topical | Once daily, up to 84 days | 72 |
Note the 1000-fold gap. The US programme dosed in hundreds of milligrams IV; the later recombinant programme dosed in micrograms per kilogram. These are not reconcilable into a single “human dose,” and the large Phase 3 eye trials (ARISE-3, SEER-3) missed their primary endpoints. No human subcutaneous study of Tβ4 or TB-500 exists — and subcutaneous is the route this compound is usually associated with.
Animal and in vitro
| Model | Amount | Route | Detail |
|---|---|---|---|
| Rat Achilles tendon repair — actual TB-500 fragment | 60 µg/kg/day | Intraperitoneal | Daily for 4 weeks |
| Rat stroke (Tβ4) | 2, 6, 12, 18 mg/kg; estimated optimum ~3.75 mg/kg | Intraperitoneal | From 24 h post-event, then every 3 days |
| Pig cardiac ischemia (Tβ4) | 6 mg/kg | IV infusion | Negative study — no cardioprotection found |
| In vitro, endothelial migration | ~50 nM | Cell culture | Tβ4 and the actin-binding fragment showed near-identical activity |
Half-life and metabolism
Recombinant Tβ4 given IV in humans: half-life 0.5–2.08 h, Tmax 3–15 minutes, no accumulation over 10 daily doses. No half-life has been published for TB-500 itself. A 2024 metabolism study found TB-500 is cleaved rapidly, and that the fragment showing wound-healing activity in culture was a metabolite (Ac-LKKTE) rather than the parent compound — so what the body is exposed to may not be what was injected.
Sources
Ruff D et al. Ann NY Acad Sci 2010 — PMID 20536472
Wang L et al. J Cell Mol Med 2021, recombinant hTβ4 Phase 1 PK — PMC8419156
Sosne G et al. Int J Mol Sci 2023, 0.1% RGN-259 Phase 3 — PMC9820614
Ho ENM et al. J Chromatogr A 2012, TB-500 identified as N-acetylated LKKTETQ — PMID 23084823
Kim J et al. J Chromatogr B 2024, TB-500 metabolism — PMID 38382158
Philp D et al. Angiogenesis 2003, ~50 nM activity — PMID 14500546
Nystedt J et al. Front Pharmacol 2016, negative porcine study — PMC4853610