TB-500 (Thymosin Beta-4 fragment)
Also known as: Thymosin β4 · TB4 · Prezatide · Timbetasin
A synthetic fragment of the endogenous 43-amino-acid thymosin β4 protein, studied for tissue-repair, angiogenesis, and emerging CNS regeneration and neuroprotection applications.
TB-500 is a synthetic thymosin β4 peptide fragment with tissue-repair, angiogenic, and emerging CNS regenerative effects; commercial supply quality is variable and partial-vs-full-sequence status is often unclear.
Evidence tier: C — preclinical / mechanistic evidence only
- Category
- Neuroprotection
- Half-life
- Short plasma half-life; sustained tissue effects extend beyond exposure
Section 1
Overview
TB-500 is a synthetic peptide fragment of thymosin β4, an endogenous 43-amino-acid protein that plays a critical role in G-actin sequestration, cell migration, tissue repair, and angiogenesis. The full-length thymosin β4 (rather than the truncated TB-500 sold in research-peptide markets) has been evaluated in clinical trials for wound healing, dry eye disease, and cardiovascular tissue repair; the commercial 'TB-500' available through research-chemical channels is a partial-sequence variant with debated equivalence to the full parent protein.
The peptide's relevance to cognitive-peptide research is emerging rather than established. The parent thymosin β4 has documented CNS regenerative effects — supporting axonal outgrowth after spinal-cord injury, promoting angiogenesis in the ischaemic brain, and reducing neuroinflammation in preclinical injury models. This CNS-repair activity places it at the intersection of tissue-repair and neuroprotection research, with growing academic interest in its potential cognitive-endpoint applications.
The commercial supply landscape is challenging. 'TB-500' sold through research-peptide vendors is often a partial-sequence peptide (typically the LKKTETQ core sequence) rather than the full thymosin β4 protein. Whether this partial peptide reproduces the parent protein's activity at the same magnitude is a debated question in the research literature. This reference covers the compound with that caveat.
Section 2
Discovery & History
- Thymosin β4 was isolated in the 1960s as part of the thymus-derived peptide fraction research, initially studied for immunological effects.
- The G-actin sequestration function was identified in the 1990s, providing the foundational mechanistic understanding.
- Full-length thymosin β4 clinical evaluation began in the 2000s under RegeneRx Biopharmaceuticals development, with trials for wound healing (venous stasis ulcers, epidermolysis bullosa), dry eye disease, and cardiovascular tissue repair.
- 'TB-500' as a research-peptide product emerged in the veterinary racehorse-injury market and subsequently in the broader research-peptide market; the equivalence to full-length thymosin β4 has been debated.
- CNS-regenerative research applications have emerged from academic groups, particularly around spinal-cord injury, stroke recovery, and traumatic brain injury contexts.
Section 3
Mechanism of Action
- 1G-actin sequestration — the fundamental cellular mechanism of thymosin β4, regulating cytoskeletal dynamics through direct binding of monomeric G-actin and maintenance of the polymerisation-ready actin pool that underlies cell migration, tissue repair, and wound healing.
- 2Promotion of angiogenesis — measurable increases in vascular endothelial growth factor (VEGF) expression, endothelial cell migration and tube formation, and neovascularisation in tissue-injury and wound-healing models across multiple tissue systems.
- 3Anti-inflammatory effects — reduction of pro-inflammatory cytokine expression (TNF-α, IL-1β, IL-6), attenuation of NF-κB signalling, and modulation of macrophage activation phenotype toward the resolution-oriented M2 state in injury contexts.
- 4Anti-apoptotic effects supporting cell survival in stressed and injured tissue — preservation of mitochondrial membrane potential, reduced caspase-3 activation, and improved cellular viability in ischaemic and oxidative stress models.
- 5CNS-specific effects — reported support of axonal outgrowth after spinal cord injury, promotion of oligodendrocyte differentiation with implications for remyelination, and reduction of glial scarring in traumatic injury models.
- 6Angiogenic and neuroprotective effects in cerebral ischaemia models — reduced infarct volume, improved functional recovery, and preserved histological outcome in rodent stroke models; the mechanistic scaffold for the emerging cognitive-endpoint research applications.
- 7Reported effects on adult neurogenesis in some preclinical models — increased BrdU-positive dentate gyrus neuron counts and preserved cognitive performance in aged animals following chronic administration.
- 8Effects on stem cell mobilisation and tissue-progenitor recruitment, extending the tissue-repair mechanism into regenerative-medicine research contexts and linking the compound to broader tissue-repair peptide research.
- 9Modulation of laminin, MMP-2, and MMP-9 expression contributing to extracellular matrix remodelling — a mechanism-of-action angle for the observed tissue-repair effects distinct from the direct angiogenic and anti-inflammatory contributions.
Section 4
Researched Benefits
Findings reported in the published preclinical and clinical literature. Effects in research contexts do not constitute claims of therapeutic benefit in humans.
- 1Tissue-repair effects across multiple tissue systems — wound healing, cardiac tissue repair, dry-eye and epidermal indications, plus emerging CNS-regenerative applications.
- 2Angiogenic effects supporting post-injury neovascularisation and tissue recovery, quantified through VEGF expression and neovessel-density endpoints in preclinical injury models.
- 3Reported CNS-regenerative effects in spinal-cord injury, stroke, and traumatic brain injury preclinical models — the strongest evidence base for cognitive-adjacent research applications.
- 4Anti-inflammatory effects with cognitive-relevance implications in neuroinflammation-driven cognitive decline models, providing an indirect mechanism-of-action angle for cognitive-endpoint research.
- 5Clinical trial evaluation of full-length thymosin β4 in multiple non-CNS indications, providing a partial safety database with acute-tolerability characterisation.
- 6Reported gut-mucosa protective effects overlapping with the BPC-157 activity spectrum, extending the gut-brain-axis relevance angle.
- 7Preclinical adult-neurogenesis effects extending the compound's positioning beyond pure tissue-repair into cognitive-plasticity research contexts.
- 8Stem-cell-mobilisation effects providing a broader regenerative-medicine research application context.
Section 5
Theoretical Dosing & Protocols
| Route | Dosage | Frequency | Duration | Source |
|---|---|---|---|---|
| Subcutaneous / intramuscular (research) | Milligram range in most research protocols | Not stated | Not stated | None cited |
Note: Research-chemical 'TB-500' may not reproduce full-length thymosin β4 activity; this uncertainty should inform protocol selection.
Section 6
Administration Routes
- Subcutaneous injection — the primary route in research applications and the practical route for the peptide.
- Intramuscular administration in some research contexts.
- Intravenous administration in acute-injury clinical trial research.
- Oral administration is not viable — the peptide is degraded by gastrointestinal proteases.
Section 7
Safety Profile
Commonly reported
- · Well-tolerated in the clinical trial evaluations at doses studied — the RegeneRx-sponsored trials of full-length thymosin β4 established acute-tolerability characterisation.
- · Injection-site reactions with subcutaneous administration — typically mild local reactions with transient erythema or tenderness.
- · Mild transient headache reported in some subjects during initial dosing, generally resolving as the tolerance-adaptation curve completes.
- · No dependence, tolerance, or withdrawal phenomena documented in the clinical or preclinical research base.
- · Occasional mild fatigue or mild mood changes reported at low frequency in some research protocols.
Rare / theoretical
- · Long-term chronic-use safety is not well-characterised outside the clinical-trial evidence base.
- · Theoretical angiogenic-effect concerns in active malignancy or angiogenesis-driven pathologies.
- · Vendor-quality issues are common with 'TB-500' commercial supply, with substantial variability in actual peptide content and purity.
- · Rare hypersensitivity reactions.
Contraindications
- · No entry for TB-500 was found in the electronic medicines compendium (emc) on 17 October 2026.
- · Active malignancy — theoretical contraindication via the pro-angiogenic mechanism.
- · Pregnancy and lactation — no controlled human data.
- · Concurrent anti-angiogenic pharmaceutical therapy.
Section 8
UK & EU Regulatory Context
United Kingdom
No entry for TB-500 was found in the electronic medicines compendium (emc) on 17 October 2026. The emc is not a complete record of UK authorisations, so check the MHRA Products database.
European Union
Not approved by the EMA. Development-programme evaluations in specific indications.
Section 9
Clinical Studies Summary
Thymosin β4 in spinal cord injury regeneration
Preclinical rodent model of contusion spinal cord injury with thymosin β4 administration reporting supported axonal outgrowth quantified by neurofilament staining, reduced glial scarring measured by GFAP expression, oligodendrocyte differentiation with remyelination markers, and improved functional recovery on Basso-Beattie-Bresnahan locomotor scale versus vehicle controls. The core evidence base for the CNS-regenerative research angle.
Thymosin β4 in cerebral ischaemia
Rodent model of middle-cerebral-artery-occlusion cerebral ischaemia with thymosin β4 administration reporting reduced infarct volume, preserved neurological function on standardised behavioural scoring, angiogenic recovery quantified in the peri-infarct zone by CD31 immunohistochemistry, and improved functional outcomes over 30-day follow-up. Extends the tissue-repair mechanism into a specifically CNS-relevant injury context.
Thymosin β4 clinical trials in wound healing
RegeneRx-sponsored clinical trial programme evaluating full-length thymosin β4 in venous stasis ulcers and epidermolysis bullosa, providing the licensed-indication-adjacent safety database and the clinical-trial evidence framework for the compound. The trials generated the acute-tolerability characterisation that supports subsequent research applications despite not resulting in marketing authorisation.
TB-500 and adult neurogenesis
Preclinical study reporting increased BrdU-positive dentate gyrus neurogenesis in aged animals receiving chronic TB-500 administration over 6 weeks, providing a preliminary link to the cognitive-relevance research angle that has motivated continued academic interest and providing empirical support for the neurogenic-adjacent research application.
Section 10
Frequently Asked Questions
Section 10a
Practical Research Guidance
Cycle guidance
Reconstitution & storage
UK sourcing notes
Section 11
Sourcing for Laboratory Research
Sourcing TB-500 (Thymosin Beta-4 fragment) for laboratory research
Researchers in the United Kingdom and elsewhere typically obtain TB-500 (Thymosin Beta-4 fragment) from specialist research-chemical suppliers. Purity, third-party testing, and supplier transparency are the principal differentiators worth evaluating before placing an order. The two suppliers below are commonly referenced in UK research contexts.
Reminder: this page is educational. Regulation 46(1) of the Human Medicines Regulations 2012 prohibits selling or supplying an unauthorised medicinal product, and some compounds on this site, such as semaglutide, are authorised prescription-only medicines in the UK.