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Script TB-500

EVIDENCE HEATMAP / QUESTION INDEX

TB-500 questions, answered straight

Twenty-five questions on TB-500 — identity, mechanism, the cardiac signal, safety, dosage, and access — each answered directly and graded by the heat of its evidence.

Read the researchLegal status and access

Identity and use

What TB-500 is, what its name means, and what it is studied for.

What is TB-500?

TB-500 is the synthetic N-acetylated heptapeptide Ac-LKKTETQ, corresponding to the actin-binding region (residues 17–23) of the 43-amino-acid protein thymosin beta-4. It is a single synthetic peptide fragment of about 889 Da — not the full-length parent protein, and not a blend.

What does TB-500 stand for and what does TB stand for in TB-500?

TB refers to thymosin beta. TB-500 is a research and veterinary designation for the synthetic Ac-LKKTETQ fragment of thymosin beta-4, not an abbreviation for the full protein. The number is a product-style identifier, not a measure of dose or size.

What is TB-500 used for in research?

It is studied in animal and in-vitro models of wound healing, tissue repair, angiogenesis, and cardiac and neurological injury [5]. It has no approved human therapeutic indication. The interest centers on the actin-binding and cell-migration activity of the parent protein, thymosin beta-4.

What is the difference between TB-500 and BPC-157?

TB-500 is the actin-binding heptapeptide fragment of thymosin beta-4; BPC-157 is a distinct gastric-derived pentadecapeptide. A 2026 Sports Medicine review lists both among unapproved peptides with favorable animal tissue-repair data but scarce human safety data [11].

Mechanism and the heart

How TB-500 acts on actin, and the cardiac findings that form the hottest cluster.

How does TB-500 work?

Its LKKTETQ motif binds and sequesters monomeric G-actin, regulating cytoskeletal dynamics and cell migration [1]. Full-length thymosin beta-4 additionally drives angiogenesis and PINCH-ILK-Akt survival signaling in animal models [2]. The fragment carries the actin-binding core but is not proven to reproduce all downstream effects.

Does TB-500 affect the heart?

Full-length thymosin beta-4 activates the PINCH-ILK-Akt survival pathway and mobilizes epicardial progenitors in animal hearts [2][7]. Whether the TB-500 7-mer reproduces this in humans is unproven. The cardiac evidence is animal-model and parent-protein, with no completed controlled human trial of the fragment.

Is TB-500 cardioprotective after a heart attack?

In rodent myocardial-infarction models, thymosin beta-4 was reported cardioprotective and improved cardiac function after coronary ligation [9]. A porcine ischemia-reperfusion study found no benefit, so results are mixed and not established in humans. The fragment has no completed controlled cardiac trial.

Did thymosin beta-4 improve outcomes in cardiac clinical trials?

Human thymosin beta-4 data are limited to a Phase 1 intravenous safety study [6] and topical ophthalmic RCTs. Injectable cardiac and stroke trials were registered, but an early injectable trial was withdrawn, so no efficacy outcome for the fragment is established.

Does TB-500 promote angiogenesis and is that a safety concern?

Tβ4 promotes endothelial migration and new vessel formation, which aids repair [5]. The same activity underlies the tumor-angiogenesis concern, since the protein is implicated in tumor vascularization and is overexpressed in several cancers [11]. It both helps healing and raises a theoretical risk.

Efficacy and tissue repair

What the wound, muscle, tendon, hair, and inflammation findings actually show.

Does TB-500 help wound healing?

Full-length thymosin beta-4 accelerated re-epithelialization by 42% at 4 days and up to 61% at 7 days in a rat wound model, with increased contraction, collagen, and angiogenesis [3]. The fragment carries the actin-binding domain that underlies this, but human wound efficacy is unproven.

Does TB-500 work for muscle tears and recovery from exercise?

Thymosin beta-4 recruits myoblasts to injured muscle in animal models, but in dystrophin-deficient mice it increased regenerating fibers without improving strength [5]. Human exercise-recovery efficacy for the fragment is unproven; the recruitment effect has not produced a measured functional gain.

Can TB-500 help with tendon injuries and ligament repair?

Thymosin beta-4 enhanced medial collateral ligament healing in rats, one of few direct connective-tissue findings [5]. Human tendon and ligament efficacy of the fragment is unproven. Most of the repair literature concerns wound and epithelial tissue rather than tendon specifically.

Does TB-500 increase hair growth?

Nanomolar thymosin beta-4 activated hair-follicle bulge stem cells and accelerated hair growth in rats and mice [5]. No human hair-growth evidence exists for the TB-500 fragment. The finding sits in the preclinical band and has not been tested in controlled human trials.

Does TB-500 have neuroprotective effects on the brain?

In a rat embolic-stroke dose-response study, intraperitoneal thymosin beta-4 at 2 and 12 mg/kg improved neurological function while 18 mg/kg did not — a non-monotonic response [4]. The benefit is animal-only; there is no human neuroprotection evidence for the fragment.

Does TB-500 reduce inflammation?

In vitro and in-vivo work reports anti-inflammatory and anti-apoptotic signaling for full-length Tβ4 [5], and recent rodent studies show anti-fibrotic effects in liver via the MAPK/NF-κB pathway [14]. Clinical anti-inflammatory benefit is unestablished, and the fibrosis role is context-dependent [15].

Safety and timeline

The tumor signal, long-term unknowns, side effects, and how the animal timelines read.

Does TB-500 cause cancer or promote tumor growth?

Thymosin beta-4 is overexpressed in several cancers and implicated in metastasis and tumor angiogenesis [11]. The same pro-migratory, pro-angiogenic properties that aid repair could theoretically support tumor progression. This is an unresolved safety signal, not a demonstrated human cancer risk for the fragment.

What are the side effects of TB-500?

Human safety data for the fragment are scarce. The Phase 1 intravenous study of full-length thymosin beta-4 reported only mild-to-moderate adverse events to 1260 mg, with no dose-limiting toxicities [6]. The main theoretical concern is the unresolved tumor-angiogenesis signal [11].

Is TB-500 safe for long-term use?

There are no long-term human safety studies of the TB-500 fragment. The tumor-angiogenesis signal [11] and the absence of completed controlled trials mean long-term safety is unknown. The only human data come from a short Phase 1 study of the parent protein [6], not the fragment.

Are there any human clinical trials on TB-500?

No completed controlled trials of the TB-500 fragment exist. Human data are limited to full-length thymosin beta-4: a Phase 1 intravenous safety study, well tolerated to 1260 mg [6], and topical ophthalmic dry-eye RCTs. Efficacy of the 7-mer in humans is not established.

How long does it take for TB-500 to work for injury healing?

In rat wound models, topical or intraperitoneal thymosin beta-4 increased re-epithelialization by about 42% at 4 days and up to 61% at 7 days [3]. There is no validated human healing timeline for the fragment; these are animal-model endpoints, not a predicted human schedule.

What is the half-life of TB-500?

No validated human pharmacokinetic half-life exists for the TB-500 heptapeptide. In the intravenous Phase 1 study of full-length thymosin beta-4, half-life increased with dose [6], but that is the parent protein. Anti-doping assays characterize the fragment for detection, not for human PK.