TB-500
A synthetic fragment of thymosin beta-4 studied for tissue repair, cell migration, and systemic recovery — most famous as BPC-157's partner in the "Wolverine stack."
TB-500 is marketed as the acetylated 7-amino-acid actin-binding domain (Ac-LKKTETQ) of thymosin beta-4, a 43-amino-acid intracellular protein central to actin regulation, cell migration, angiogenesis, and wound healing. A persistent quirk of the market is that many vials sold as "TB-500" actually contain the full-length 43-amino-acid protein rather than the short fragment — only a mass-spectrometry COA resolves which. Preclinical evidence for the thymosin beta-4 biology (wound, cardiac, corneal, renal, and neural repair) is deep and reproducible, but direct human clinical data on the fragment itself is essentially absent, and the full-protein clinical program has missed its pivotal trials.
Class
Synthetic peptide fragment of thymosin beta-4 (heptapeptide, actin-binding domain)
Half-life
Reported ranges vary widely — human Phase 1 PK data (PMID 34346165) indicates ~0.5–2 hours for the fragment, animal estimates suggest ~6 hours, and some vendors claim 5–7 days; the discrepancy partly reflects fragment-vs-full-protein confusion.
Routes
Subcutaneous injection, Intramuscular injection, Nasal spray (investigational, often in combination blends)
Category
Healing & Recovery
Researched benefits
What it's studied for
Accelerated wound healing
Thymosin beta-4 promotes keratinocyte and endothelial cell migration, angiogenesis, and collagen deposition, accelerating full-thickness dermal wound closure in diabetic and aged animal models (PMID 12581423, PMID 25613625). The effect is driven by actin sequestration that mobilizes cells to injury sites.
Musculoskeletal recovery
Community and preclinical interest centers on soft-tissue, muscle, and tendon repair through matrix remodeling and cell migration. Unlike BPC-157, TB-500 is reported to act systemically rather than locally, and users describe slower onset with effects that build over weeks.
Cardiac tissue repair
In myocardial infarction models, thymosin beta-4 promotes cardiomyocyte survival, reduces infarct size, and mobilizes epicardial progenitor cells via the Akt survival pathway (PMID 18286466). Its metabolite Ac-SDKP adds antifibrotic and angiogenic activity (PMID 30854877).
Anti-inflammatory activity
The peptide suppresses inflammatory signaling (reported NF-κB suppression and cytokine reduction) at injury sites, complementing its reparative actions across muscle, tendon, and cardiac tissue.
Anti-fibrotic effects
In renal fibrosis models, thymosin beta-4 reduced late-stage fibrosis through a PAI-1-dependent mechanism, and its degradation product Ac-SDKP exerted consistent antifibrotic effects at both early and late injury stages (PMID 23739235).
Hair growth promotion
Thymosin beta-4 activates hair follicle stem cell migration and differentiation via the Wnt/β-catenin/Lef-1 pathway, upregulating MMP-2 and VEGF (PMID 27130465, PMID 17947589). Community reports note hair regrowth or thickening over weeks to months.
Corneal and ocular repair
Thymosin beta-4 eye drops accelerated corneal epithelial wound closure and reduced inflammation in injury models, forming the basis of the most advanced clinical program (Phase 2/3) in the thymosin beta-4 family — though the pivotal ophthalmic trials ultimately missed their endpoints.
Mechanism
How it works
TB-500 is derived from thymosin beta-4, one of the most abundant intracellular actin-sequestering proteins in mammalian cells. Its core mechanism is binding to monomeric G-actin through the LKKTETQ motif (residues 17–23), regulating actin polymerization and depolymerization. This cytoskeletal control governs cell motility, allowing endothelial cells, keratinocytes, and muscle satellite cells to migrate toward sites of injury.
When thymosin beta-4 is released extracellularly following tissue damage, it initiates paracrine signaling cascades that drive angiogenesis, reduce inflammation, and promote cell survival. In cardiac models it activates the Akt (protein kinase B) survival pathway and mobilizes epicardial progenitor cells; in skin it accelerates re-epithelialization and matrix remodeling. Unlike BPC-157, which appears to act locally at the administration site, TB-500 is described as acting through a more systemic mechanism and does not need to be injected near the injury.
The full-length protein is also enzymatically cleaved to generate the anti-fibrotic tetrapeptide Ac-SDKP, which contributes antifibrotic and angiogenic activity across heart, arteries, lungs, and kidneys. A central scientific caveat is that the marketed 7-amino-acid fragment retains the actin-binding active site but not necessarily the full protein's stability, cellular uptake kinetics, Ac-SDKP generation, or broader cytoskeletal interactions — so whether the fragment reproduces the full biology at clinically relevant doses remains unresolved.
Nearly all mechanistic evidence derives from thymosin beta-4 and Ac-SDKP preclinical research rather than from the TB-500 fragment specifically. Animal studies consistently demonstrate tissue-reparative and anti-fibrotic effects across cardiovascular, renal, dermal, corneal, and musculoskeletal models, but human clinical translation has not been established for either the parent protein or the fragment.
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
Reconstitution
Reconstitute the lyophilized vial with bacteriostatic water. A common approach adds 1–2 mL BAC water to the vial — e.g., a 5 mg vial with 1 mL yields 5 mg/mL, while a 2.5 mg vial with 2 mL yields 1.25 mg/mL. Use a 0.5 mL insulin syringe for injection. Store lyophilized powder at -20°C; keep the reconstituted solution refrigerated at 2–8°C and use within roughly 3–4 weeks.
Beginner
- Dose
- 2.5 mg
- Frequency
- Twice per week
- Timing
- Space injections 3–4 days apart
- Duration
- 4–6 weeks
- Route
- Subcutaneous
Standard flat dosing loading phase; TB-500 is systemic and does not need to be injected near the injury site.
Intermediate
- Dose
- 5 mg loading, then 2.5 mg maintenance
- Frequency
- Twice per week loading, then once per week
- Timing
- Loading injections spaced across the week
- Duration
- 6 weeks loading, then 4 weeks maintenance
- Route
- Subcutaneous
Higher loading saturation followed by a reduced maintenance dose to sustain effects.
Advanced
- Dose
- 5 mg loading, then 5 mg maintenance
- Frequency
- Twice per week for 8 weeks, then once weekly
- Timing
- Loading twice weekly, transition to weekly ongoing
- Duration
- 8 weeks loading, then ongoing maintenance
- Route
- Subcutaneous
Often stacked with BPC-157 (500 mcg twice daily) for the "Wolverine" tissue-repair protocol.
Maintenance / Titration
- Dose
- 2.0–2.5 mg loading (weeks 1–4), 2.0 mg maintenance (weeks 5+)
- Frequency
- 2–3x weekly loading, then weekly
- Timing
- Consistent weekly scheduling
- Duration
- 4 weeks loading, then ongoing weekly
- Route
- Subcutaneous
Loading aims to saturate tissue and initiate repair; maintenance sustains angiogenic and healing effects.
- Community protocols typically use a loading phase (higher, more frequent doses for 4–8 weeks) followed by a lower-dose weekly maintenance phase.
- Dosing is generally flat rather than weight-based; standard injections are 2–5 mg.
- Because TB-500 acts systemically, it does not need to be injected at or near the injury site.
- Effects are commonly reported to have a slower onset than BPC-157, building over weeks rather than days.
- No FDA-approved human dosing framework exists; all regimens are drawn from community and veterinary practice, not controlled human trials.
- Verify whether a product is the 7-amino-acid fragment or full-length thymosin beta-4 (mass-spec COA), and whether it is the acetate or free-base form, since potency assumptions differ.
Evidence
Research & clinical studies (8)
Tβ4-Ac-SDKP pathway: Any relevance for the cardiovascular system?
Reviews experimental evidence that thymosin beta-4 and its metabolite Ac-SDKP promote cardiac repair after infarction by stimulating endothelial cell migration and cardiomyocyte survival, with antifibrotic, anti-inflammatory, and angiogenic effects across heart, arteries, lungs, and kidneys.
PMID 30854877Thymosin β4 and its degradation product, Ac-SDKP, are novel reparative factors in renal fibrosis
In mouse renal fibrosis models, thymosin beta-4 reduced late-stage fibrosis through a PAI-1-dependent mechanism while Ac-SDKP exerted consistent antifibrotic effects at both early and late injury stages.
PMID 23739235Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice
Thymosin beta-4 accelerated full-thickness dermal wound healing in diabetic and aged mice, and a seven-amino-acid synthetic fragment replicating its actin-binding domain (LKKTETQ) produced comparable repair activity in aged animals.
PMID 12581423Role of thymosin beta 4 in hair growth
In thymosin beta-4 overexpressing and knockout mice, Tβ4 promoted hair shaft formation and follicle regeneration via Wnt/β-catenin/Lef-1 signaling, upregulating MMP-2 and VEGF.
PMID 27130465Thymosin beta 4 induces hair growth via stem cell migration and differentiation
In multiple rat and mouse models, thymosin beta-4 promoted hair growth by stimulating follicle stem cell migration, differentiation, and protease production.
PMID 17947589Thymosin beta-4 promotes cardiomyocyte survival and cardiac repair after myocardial infarction
Demonstrated cardiac tissue protection and repair following myocardial infarction, with reduced infarct size and improved cardiac function attributed to progenitor cell migration and survival signaling.
PMID 18286466Accelerated wound healing through enhanced cell migration and angiogenesis
Reported accelerated wound healing driven by enhanced cell migration and angiogenesis, consistent with thymosin beta-4's actin-regulatory repair mechanism.
PMID 25613625Human Phase 1 pharmacokinetics of thymosin beta-4-derived peptide
Human Phase 1 pharmacokinetic data indicate a short, dose-dependent plasma half-life on the order of ~0.5–2 hours for the peptide.
PMID 34346165Combinations
Stacking & blends
The Wolverine Stack (BPC-157 + TB-500)
Comprehensive tissue repair and injury recovery
The flagship peptide-clinic healing pairing. BPC-157 provides localized, angiogenic, gut- and tendon-focused repair while TB-500 adds systemic cell migration and broader soft-tissue recovery — complementary steps in the healing cascade with minimal mechanistic overlap. No controlled head-to-head trial data exists, but community reports are consistent.
GLOW Blend (BPC-157 + TB-500 + GHK-Cu)
Synergistic tissue repair, collagen synthesis, and anti-inflammatory support
Adds GHK-Cu's collagen-synthesis and anti-inflammatory signaling to the BPC-157/TB-500 pairing, studied in research contexts for combined effects across musculoskeletal, connective-tissue, and wound-healing applications.
TB-500 + PEG-MGF
Muscle repair and regeneration
Pairs TB-500's systemic anti-inflammatory and actin-binding tissue-repair properties with PEG-MGF's localized satellite cell activation, researched for accelerating recovery from muscle injury and supporting lean tissue regeneration.
Safety
Side effects & considerations
Commonly reported effects
Contraindications & cautions
- Active cancer or cancer history (theoretical concern given angiogenic and tissue-growth-promoting properties)
- Pregnancy or breastfeeding
- Known hypersensitivity to thymosin beta-4 fragments
No serious adverse events have been documented in the available preclinical literature, and community reports are generally clean. However, human safety data are limited, long-term effects at sustained research-use dosing are uncharacterized, and the theoretical angiogenesis/tumor-proliferation concern has not been clinically resolved. Anyone with a cancer history should consult a physician before use.
FAQ
TB-500 — common questions
What is TB-500?
TB-500 is marketed as the acetylated 7-amino-acid actin-binding fragment (Ac-LKKTETQ, residues 17–23) of thymosin beta-4, a 43-amino-acid intracellular protein involved in actin regulation, cell migration, angiogenesis, and wound healing. It is sold as a research chemical for tissue-repair and anti-inflammatory applications, mostly in the sports-recovery community.
Is TB-500 the same as thymosin beta-4?
Not exactly. The name "TB-500" denotes the short 7-amino-acid fragment, but independent mass spectrometry finds that many vials sold as TB-500 actually contain the full 43-amino-acid protein (~4963 Da), and the same CAS number is used for both. Only a COA with a measured mass tells you which molecule is in the vial.
How does TB-500 compare to BPC-157?
They are the two flagship tissue-repair peptides and are often paired in the "Wolverine stack." BPC-157 tends to act locally and skews toward gut and tendon repair, while TB-500 acts more systemically and is reported to favor muscle and broader soft-tissue recovery with a slower onset. No formal head-to-head comparison data exists.
How is TB-500 dosed?
Community protocols typically use a loading phase of 2.5–5 mg subcutaneously twice weekly for 4–8 weeks, followed by a 2–2.5 mg weekly maintenance dose. Dosing is flat rather than weight-based, and because the peptide acts systemically it does not need to be injected near the injury. No FDA-approved human dosing framework exists.
Does TB-500 cause cancer?
A theoretical concern about angiogenesis promoting the growth of existing tumors has been raised (similar to BPC-157), given thymosin beta-4's role in vascular development, but it has not been clinically substantiated. Anyone with active cancer or a cancer history should consult a physician before considering it.
Is TB-500 FDA approved or legal?
No. TB-500 is not approved for any indication anywhere. It was removed from the FDA's Category 2 bulk-substances list in April 2026 and scheduled for PCAC review in July 2026 for a proposed wound-healing use, but it remains sold only as a research chemical and is not approved for human consumption.
Does TB-500 show up on a drug test?
Yes. TB-500 and thymosin beta-4 derivatives are on the WADA Prohibited List (Section S2 — Peptide Hormones, Growth Factors). A detection method was first published in 2011, and methods have since improved, so it is prohibited in competition for tested athletes.
What is TB-500 Frag, and is it the same thing?
TB-500 Frag is the explicitly stripped 7-amino-acid LKKTETQ heptapeptide (CAS 885340-08-9, ~858 Da), sold as a cheaper alternative because it is roughly 6x cheaper to synthesize than the full protein. It retains the actin-binding chemistry in vitro, but community reports and evidence favor the full peptide for injury-recovery outcomes, and direct comparative human data is absent.
