MUSCLE GROWTHPreclinicalMUSCLE RECOVERYCARDIAC REPAIRHAIR GROWTH

TB-500

Also known as: Thymosin Beta-4 · Tβ4 · Thymosin-β4

31.4k views/week 612 citations 0 edits Updated 4/6/2026

TB-500 is a synthetic version of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide found in virtually all human and animal cells. It plays a critical role in tissue repair, wound healing, and the regulation of actin polymerization.

STRUCTURE

Molecular Composition

FORMULA
C₃₄H₅₆N₁₀O₁₄
MOL. WEIGHT
820.87 Da
SEQUENCE LENGTH
7 amino acids
CAS NUMBER
77591-33-4
ORIGIN
Thymosin β₄ fragment
SOLUBILITY
Water-soluble
AMINO ACID CHAIN VISUALIZATION
L
Leucine
actin-binding start
NH-CO
K
Lysine
charge anchor
NH-CO
K
Lysine
charge anchor
NH-CO
T
Threonine
actin sequestration
NH-CO
E
Glutamate
flexibility
NH-CO
T
Threonine
actin sequestration
NH-CO
Q
Glutamine
C-terminal cap
SEQUENCEL-K-K-T-E-T-Q
MECHANISMS

How It Works

🔗
Actin Sequestration
TB-500 binds G-actin monomers via its LKKTETQ domain, promoting cell migration and proliferation — the two key drivers of tissue repair. This mechanism is unique among peptides in the healing category.
🛡
Systemic Anti-inflammation
Downregulates pro-inflammatory cytokines (IL-1β, TNF-α) at a systemic level. Unlike BPC-157, TB-500 acts body-wide rather than locally, making it particularly effective for multi-site or chronic inflammation.
❤️
Cardiac & Muscle Repair
Strong evidence for promotion of cardiomyocyte regeneration and skeletal muscle satellite cell activation. One of the few peptides with demonstrated cardiac repair activity in animal models of MI.
🧠
Neurological Protection
Reduces neuroinflammation and promotes neural stem cell differentiation. Studies show cognitive improvement and reduced lesion size in TBI animal models.
OVERVIEW

Research Overview

Thymosin Beta-4 is one of the most abundant peptides in the body, with concentrations particularly high in platelets and wound fluid. TB-500 is a synthetic analog developed to mirror the biological activities of the naturally occurring protein.

Its unique capacity to promote cell migration and differentiation makes it particularly valuable in cardiac and skeletal muscle repair research. TB-500 has been studied extensively in animal models and is widely used in veterinary medicine for tendon and ligament injuries in racehorses.

Mechanism of Action

// ACTIN SEQUESTRATION

TB-500's primary mechanism involves binding to actin via its central domain. By sequestering G-actin, TB-500 promotes cell migration, differentiation, and proliferation — all critical steps in wound healing.

// UPREGULATES CELL SURFACE RECEPTORS

TB-500 upregulates integrin receptors and metalloproteinase enzymes that break down the extracellular matrix, allowing newly formed cells to migrate into damaged tissue.

SEQUENCE

Amino Acid Sequence

Ac-Ser-Asp-Lys-Pro-Asp-Met-Ala-Glu-Ile-Glu-Lys-Phe-Asp-Lys-Ser-Lys-Leu-Lys-Lys-Thr-Glu-Thr-Gln-Glu-Lys-Asn-Pro-Leu-Pro-Ser-Lys-Glu-Thr-Ile-Glu-Gln-Glu-Lys-Gln-Ala-Gly-Glu-Ser
DOSAGE

Dosage & Administration

INJECTABLE (SUBCUTANEOUS) — LOADING
DOSE
2–2.5 mg
FREQUENCY
Twice weekly for 4–6 weeks
NOTES
Loading phase for acute injury or systemic inflammation. Inject into subcutaneous fat near the injury site. Reconstitute with bacteriostatic water.
INJECTABLE (SUBCUTANEOUS) — MAINTENANCE
DOSE
2 mg
FREQUENCY
Once weekly
NOTES
Maintenance phase following loading. Used to sustain anti-inflammatory and repair effects over longer periods.
INJECTABLE (INTRAMUSCULAR)
DOSE
2 mg
FREQUENCY
Twice weekly
NOTES
Alternative route for deeper musculoskeletal injuries. Absorption is comparable to subcutaneous with slightly faster peak levels.

TB-500 is the synthetic analogue of the active fragment of Thymosin Beta-4, a naturally occurring peptide found in virtually all human and animal cells. It has a strong safety profile in animal research. No human clinical trials published. Store lyophilized powder at −20°C; reconstituted solution at 4°C for up to 30 days.

CYCLING

Cycle Duration Guide

ON CYCLE
4–6 weeks (loading), then maintenance as needed
OFF CYCLE
4–8 weeks after loading phase

A typical protocol consists of a 4–6 week loading phase (twice weekly injections) followed by a maintenance phase or complete off-cycle. Many researchers take an extended break after loading and resume only if symptoms return. The long half-life means effects persist well beyond the last injection.

Quick Reference
FORMULAC₂₁₂H₃₅₀N₅₆O₇₈S
MOL. WEIGHT4,963.5 Da
LENGTH43 amino acids
ORIGINNaturally occurring in most mammalian cells; synthetic version for research use
HALF-LIFE~20 hours (subcutaneous)
SOLUBILITYSoluble in bacteriostatic water or sterile saline
STATUSPreclinical
Ask AI

Ask anything about TB-500 — mechanisms, dosing protocols, interactions, or research comparisons.

TAGS
muscle recoverycardiac repairhair growthactin binding