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Tissue Repair & Anti-Inflammatory

TB-500 / Thymosin Beta-4

Thymosin beta-4 fragment that promotes cell migration and angiogenesis; strong animal repair data, no human trials of TB-500.

RestrictedEvidence level 2 of 5: Animal data, minimal humanAlso: Thymosin β4, Tβ4, Ac-LKKTETQ, RGN-259 (ophthalmic Tβ4), RGN-137 (topical Tβ4)

Overview

Thymosin beta-4 is a 43-amino-acid peptide present in nearly all cells, where it binds actin and controls how cells move and remodel. Released at injury sites, it promotes migration of endothelial and progenitor cells, new blood vessel growth, reduced inflammation and wound closure. 'TB-500' usually refers to a short synthetic fragment (Ac-LKKTETQ) containing the actin-binding region, sold as a research peptide. Animal studies show faster healing of skin, tendon, muscle, heart and cornea. Human studies have used the full-length protein as eye drops for dry eye and neurotrophic keratitis and as a topical gel for chronic ulcers, with mixed results. No controlled studies have tested the TB-500 fragment in people, and its angiogenic action warrants caution with cancer.

Classification
Synthetic fragment (Ac-LKKTETQ) of thymosin beta-4, a 43-amino-acid endogenous actin-binding peptide
Route
Subcutaneous
Half-life
~2–3 hours (SC, estimated); human PK of TB-500 not characterized

Mechanism of action

Primary targetG-actin sequestration and cell-migration signaling
  1. Subcutaneous injectionPeptide distributes systemically, reaching injured tissue.
  2. G-actin bindingRegulates actin polymerization, enabling cell shape change and movement.
  3. Cell migration and angiogenesisEndothelial and keratinocyte migration and new vessel formation increase.
  4. Progenitor cell mobilizationStem and progenitor cells are recruited to the injury site.
  5. Inflammation dampenedNF-κB signaling and TNF-α, IL-1β levels decline.
Downstream effects
  • Soft-tissue repair
  • Wound closure
  • Reduced inflammation

Researched for

  • Soft-tissue and tendon injury
  • Chronic wounds and ulcers
  • Dry eye and neurotrophic keratitis (Tβ4)
  • Cardiac repair after infarction (animal)
  • Hair regrowth (animal)

Research notes

  • Animal studies (Bock-Marquette 2004; Malinda 1999) show improved cardiac repair and dermal wound healing.
  • Full-length Tβ4 eye drops (RGN-259) showed some sign/symptom improvements in Phase 3 dry-eye trials but inconsistent primary endpoints.
  • Topical Tβ4 gel (RGN-137) produced trends toward faster healing of venous ulcers in Phase 2.
  • The TB-500 fragment has no published human safety or efficacy data; product purity varies.

Reported side effects

  • Injection-site reactions
  • Headache
  • Transient fatigue or lightheadedness
  • Theoretical tumor-growth promotion (angiogenic)

Contraindications & cautions

  • Active cancer or malignancy within 5 years
  • Pregnancy and breastfeeding
  • Proliferative retinopathy (caution)
  • Competitive athletes (WADA-prohibited)

Lab monitoring

  • CBC, CMP
  • CRP, ESR
  • Vitamin D, zinc
  • Imaging of injured area as indicated
  • Baseline pain and function scores

Dosing and pricing for TB-500 / Thymosin Beta-4

Dosing references and compound pricing are available to established patients in the secure portal after a medical evaluation.

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