TB-500
TB-500 is a synthetic fragment of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid protein found in virtually all mammalian cells. Thymosin Beta-4 was first isolated from bovine thymus tissue and later discovered to be one of the most abundant intracellular peptides in the human body. TB-500 consists specifically of the amino acid sequence 17–23 of the full Tβ4 protein, the region responsible for most of its biological activity.
- also known as
- Thymosin Beta-4 fragment
- route
- subcutaneous or IM
- cadence
- 2× per week (loading), weekly (maintenance)
- storage
- refrigerated · 28-day max
- typical dose
- 2–2.5 mg per injection
- cycle
- 4–6 week loading · ongoing maintenance
What is TB-500?
TB-500 is a synthetic fragment of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid protein found in virtually all mammalian cells. Thymosin Beta-4 was first isolated from bovine thymus tissue and later discovered to be one of the most abundant intracellular peptides in the human body. TB-500 consists specifically of the amino acid sequence 17–23 of the full Tβ4 protein, the region responsible for most of its biological activity.
The primary mechanism of TB-500 centers on actin regulation. Actin is the structural protein that forms the cytoskeleton of cells; Thymosin Beta-4 sequesters G-actin (the soluble monomer form), influencing how cells migrate, differentiate, and respond to injury. This has downstream effects on three key repair processes: angiogenesis (formation of new capillaries to restore blood supply to damaged tissue), anti-inflammatory modulation (reducing cytokine activity at injury sites), and satellite cell activation (the muscle stem cells responsible for muscle fiber repair and growth).
In animal models, TB-500 has demonstrated consistent healing acceleration in cardiac tissue (particularly relevant post-myocardial injury), tendons, ligaments, muscles, and even central nervous system tissue. A series of rodent studies showed TB-500 reduced cardiac scar formation after induced heart attacks and promoted recruitment of cardiac progenitor cells. For musculoskeletal applications, healing of tendon and ligament tears was significantly accelerated compared to controls.
Reconstituting TB-500 follows standard peptide protocol. Add bacteriostatic water slowly to the lyophilized powder and gently roll the vial to mix, never shake. A 5 mg vial with 2 mL BAC water gives 2,500 mcg/mL. At a 2.5 mg dose, you would draw 1 mL (100 units on U-100). Refrigerate at 2–8°C after reconstitution; stable for approximately 28 days. Common injection sites are the abdomen or thigh subcutaneously, though intramuscular injection into the site of injury is sometimes used.
TB-500 is often used in a two-phase protocol: a loading phase of 2–2.5 mg two or three times per week for 4–6 weeks to saturate tissue, followed by a maintenance phase of 2–2.5 mg once weekly. The loading phase is intended to establish elevated Tβ4 fragment levels in the circulation more rapidly. TB-500 is sometimes stacked with BPC-157 for synergistic injury recovery, both peptides promote healing but through distinct and complementary pathways.