Thymosin Beta-4
Full-length 43-amino-acid G-actin sequestering peptide — the parent molecule of TB-500. Studied for wound healing, cardiac repair post-MI, corneal repair, and hair regrowth.
🔬 Mechanism of Action
Thymosin Beta-4 (Tβ4) is a 43-amino-acid peptide that is the primary intracellular G-actin sequestering molecule in mammalian cells. Unlike its fragment TB-500, full-length Tβ4 contains the complete actin-binding domain plus additional N- and C-terminal regions that contribute to anti-inflammatory and regenerative signaling. Tβ4 promotes cell migration by maintaining the G-actin monomer pool for rapid cytoskeletal remodeling, stimulates angiogenesis via induction of VEGF and angiopoietin-2, and reduces inflammation by inhibiting NF-κB nuclear translocation. In cardiac models, Tβ4 activates cardiac progenitor cells expressing Isl1+ markers, promoting cardiomyocyte differentiation after myocardial infarction.
Source: PMID: 20514133
📜Background & History
Thymosin Beta-4 is the most abundant member of the beta-thymosin family, present in virtually all nucleated cells at concentrations of 0.1-0.5 mM. TB-500, the widely used research peptide, is actually a 17-amino-acid fragment of this 43-amino-acid molecule. Full-length Tβ4 has been studied for cardiac repair (RegeneRx Biopharmaceuticals), corneal wound healing (RGN-259 eye drops), and epidermolysis bullosa. It represents one of the most promising endogenous repair molecules.
🎯 Research Use Cases
- ✓Cardiac repair post-MI
- ✓Corneal wound healing
- ✓Hair regrowth
- ✓Chronic wound healing
- ✓Epidermolysis bullosa
💉 Dosing Protocol
| Typical Dose | 750-2000 mcg/day |
| Frequency | 1× daily for 10-20 days |
| Half-Life | 2 hours |
| Common Vial Sizes | 5 mg |
🧪 Reconstitution Example
⚠️Safety & Considerations
Generally well-tolerated in animal studies and limited clinical trials. Similar safety profile to TB-500 but with potentially greater biological activity per dose. Research-only compound — not FDA-approved for any indication.
⚡Interactions & Contraindications
Research compound — no established drug interactions. Theoretical concern with tumor promotion in predisposed individuals (actin dynamics role in metastasis) though not observed in clinical studies.
🔗Synergies & Common Stacks
TB-500 is the fragment; full-length Tβ4 contains the complete molecule. Some practitioners use both at different phases of recovery.
Tβ4 + BPC-157 targets distinct repair pathways: Tβ4 for actin dynamics/cell migration, BPC-157 for angiogenesis and GH receptor upregulation.