TB-500
Actin-binding peptide fragment
A synthetic fragment of Thymosin Beta-4 frequently studied alongside BPC-157 in repair-related research.
Also referenced as: Thymosin Beta-4
Overview
TB-500 is a synthetic peptide commonly described as corresponding to the actin-binding domain (a short fragment, often the LKKTETQ region) of Thymosin Beta-4, a naturally occurring 43-amino-acid protein involved in actin regulation. TB-500 is produced synthetically and is not identical to full-length Thymosin Beta-4.
At a glance
What TB-500 does
TB-500 refers to a synthetic peptide corresponding to thymosin beta-4 (Tβ4) or its active fragment, and its defining action is regulation of the actin cytoskeleton. Thymosin beta-4 is the body's principal G-actin-sequestering protein: it binds monomeric (globular) actin and holds a large intracellular pool in a polymerization-ready but inactive state, releasing it when a cell needs to migrate, extend, or remodel. By governing this actin supply, TB-500 accelerates the cell movement that underlies wound closure, tissue repair, and blood-vessel formation.
Beyond actin binding, preclinical work shows Tβ4 promotes endothelial cell migration and tube formation (angiogenesis), upregulates matrix and repair-related genes, and reduces pro-inflammatory cytokine signaling, which dampens excess inflammation and may limit fibrotic scarring. In injury models it increases collagen deposition and vascular density in healing wounds, and it has been studied for cardiac, corneal, dermal, and neural repair. Its actions are systemic in the sense that circulating peptide can reach distant injury sites rather than acting only where applied.
The state of the evidence is important: most published data on the TB-500 fragment itself come from rodent and cell-culture studies. The strongest human clinical evidence involves the full-length parent protein thymosin beta-4 (for example, topical formulations for corneal and skin wounds), not the shortened TB-500 sequence sold for research. So while the mechanistic story is well characterized, human efficacy for TB-500 specifically remains largely unproven.
Effects reported in research
- Sequesters monomeric G-actin and regulates actin polymerization, enabling faster cell migration and tissue remodeling (established biochemistry).
- Promoted increased collagen deposition and vascular density in preclinical excisional and diabetic wound-healing models (animal only).
- Stimulated endothelial cell migration and tube formation, supporting angiogenesis (in-vitro and animal).
- Reduced pro-inflammatory cytokine output, associated with dampened inflammation and less scar/fibrosis in injury models (animal/in-vitro).
- Improved recovery in cardiac injury models, promoting cardiomyocyte survival and vessel growth (animal, mostly full-length Tβ4).
- Supported corneal and dermal wound repair, with the strongest human data coming from full-length thymosin beta-4 formulations, not the TB-500 fragment.
- Upregulated cell-surface receptors and repair-associated gene expression involved in migration and regeneration (in-vitro).
- Human clinical evidence for the TB-500 fragment specifically is limited; most rigorous results use the larger parent protein.
Effects listed reflect findings reported in the research literature — many in animal or in-vitro models. Listing an effect is not a claim of efficacy or a therapeutic indication in humans.
Mechanism of action
Thymosin Beta-4 and its actin-binding fragment are studied for their ability to sequester G-actin and influence actin polymerization, which relates to cell migration. In preclinical models, this activity has been linked to cell migration, angiogenesis and tissue-repair processes. These mechanisms are drawn largely from animal and cell-culture research and are not established in controlled human trials for TB-500 itself.
Mechanistic description reflects published research-literature understanding. Much peptide research is preclinical (in-vitro or animal-model); mechanism in humans may differ and is not established for many compounds.
What it's studied for
Research contexts in which TB-500 appears in the literature. Listing a research area is not a claim of efficacy or a therapeutic indication.
Key characteristics
- Marketed as a fragment related to the actin-binding region of Thymosin Beta-4
- The parent protein Thymosin Beta-4 is a well-characterized natural actin-sequestering peptide
- Research on repair endpoints is predominantly preclinical
- Prohibited in sport by the World Anti-Doping Agency
- Not an approved drug and not identical to full-length Thymosin Beta-4
Reported research dosing reference only
Educational reference, not dosing guidance. The figures below summarize amounts reported in published research and research-community protocols, provided for educational and research context only. They are not medical advice, not a recommendation, and not instructions for human use. TB-500 is a research compound.
Research-protocol summaries for TB-500 generally describe weekly milligram-range dosing split into a few subcutaneous administrations, with a multi-week loading phase followed by a lower maintenance phase. These are literature/protocol reference figures for research context only, not human dosing guidance.
- Common research-protocol reference: ~2-10 mg per week, divided into 2-3 subcutaneous doses
- Reported loading phase: ~5-10 mg/week for 4-6 weeks, then maintenance ~2-5 mg/week
Reported elimination half-life ~2-3 hours with effects described as persisting for days. Identity varies by vendor between full-length thymosin beta-4 and the 17-23 fragment, so confirm against the COA.
How it compares
TB-500 is defined by its actin-binding fragment identity, distinguishing it from BPC-157's growth-factor/angiogenesis focus and from copper tripeptides used cosmetically.
Commonly studied alongside
Compounds frequently researched together with TB-500 in the literature. Cross-referenced for research context — not a usage or combination recommendation.
Handling & Stability
Lyophilized peptides are stored cold, protected from light, and reconstituted only at the time of intended in-vitro work.
- Avoid repeated freeze-thaw cycles
- Verify supplier lot and Certificate of Analysis
- Follow institutional lab-safety protocols
Analytical & COA Concepts
Reputable research suppliers publish a third-party Certificate of Analysis per batch. Key analytical concepts referenced in COAs include:
Category Context
TB-500 sits in the Healing & Recovery area of the PeptiDex library.
- Entry type: Research compound reference
- Browse the full library →
- Glossary of terms →
Where researchers source TB-500
For researchers studying TB-500, third-party suppliers such as Practically Natty Peptides offer research-grade material with third-party Certificates of Analysis and US-based shipping.
View research-supplier listing →
Outbound link to a third-party research supplier. Inclusion does not constitute endorsement; all editorial content is developed independently.
Frequently asked questions
What is TB-500 and how does it relate to thymosin beta-4?
TB-500 is a research peptide associated with thymosin beta-4 (Tbeta4), a 43-amino-acid actin-binding regulatory peptide. The name TB-500 is used in the research-chemical market for both full-length thymosin beta-4 (MW ~4921 Da) and, in some references, the acetylated active fragment covering residues 17-23 (Ac-LKKTETQ). Buyers should check each vendor's COA, since what is shipped as 'TB-500' varies.
What is TB-500 studied for?
In animal models it is researched for tissue repair, wound healing, angiogenesis, and cell migration, largely through thymosin beta-4's role in sequestering G-actin and regulating the actin cytoskeleton. It has also been examined in cardiac and corneal repair models. Human clinical efficacy has not been established.
What does TB-500's half-life imply for research protocols?
Reported elimination half-life is roughly 2-3 hours, but downstream tissue effects are described as persisting for days through signaling cascades. Because of this, research protocols typically use infrequent dosing (e.g. a few times per week) rather than daily, loading over several weeks before a maintenance phase.
How does TB-500 differ from BPC-157?
TB-500 works largely through actin regulation and cell migration and is dosed on the order of milligrams per week, whereas BPC-157 is a smaller gastric-derived pentadecapeptide dosed in micrograms and linked to nitric-oxide and angiogenic pathways. They are commonly co-studied as complementary repair agents rather than substitutes.
Is TB-500 permitted in sport, and is it an approved drug?
TB-500 is not an approved drug and is sold only for research use. Thymosin beta-4 and its fragments are prohibited in sport under WADA. Reported human safety data comes from limited Phase I work on the parent molecule rather than from efficacy trials.
How is TB-500 reconstituted and stored?
It is supplied lyophilized and reconstituted with bacteriostatic water, added gently and swirled rather than shaken. Reconstituted solution is stored refrigerated at 2-8 C and protected from light, while lyophilized powder is more stable and can be frozen for longer-term storage.
Answers are educational summaries of research-literature context and do not constitute medical advice. See the Research Library, COA guide, and Storage & Handling guide for more.