Synthetic thymosin beta-4 fragment
Synthetic ~7-amino-acid fragment reproducing the actin-binding region of thymosin beta-4; marketed for tissue repair. (Not full-length TB4.)
| Class / type | Synthetic thymosin beta-4 fragment |
|---|---|
| Category | Healing, Recovery & Immune |
| Status (Jul 2026) | Research use only |
TB-500 is a synthetic peptide that reproduces the active, actin-binding region of thymosin beta-4 (a natural protein involved in cell movement and repair). It is marketed for tissue repair and recovery and is frequently paired with BPC-157.
Note that TB-500 is not the same molecule as full-length thymosin beta-4 - it is a fragment with different properties. Evidence is preclinical, and it is not approved for human use.
TB-500 binds G-actin and helps regulate actin dynamics, which supports cell migration - moving repair cells into damaged tissue. In animal work it also promotes recruitment of stem/progenitor cells, new blood-vessel growth, and reduced inflammation.
Promising animal data span wound, tendon, muscle, corneal and cardiac repair. As with BPC-157, controlled human efficacy trials are lacking, so soft-tissue benefits in people remain anecdotal.
Separately, research on the parent protein thymosin beta-4 has linked it to tumor progression and metastasis in some cancer contexts, which is why the tumor concern is taken slightly more seriously here.
Users most often report improved whole-body recovery, mobility and flexibility for muscle and tendon strains, and value its synergy in blends.
Broad preclinical repair signals across many tissue types give a biological rationale.
No FDA-approved human use and limited human data mean the safety profile is not established.
It aids repair partly by encouraging new blood-vessel growth and cell migration - the same processes tumors use to grow and spread - so there is a theoretical, unproven concern it could help an undiagnosed cancer along, reinforced by thymosin beta-4's links to tumor progression. It is also banned in competitive sport (WADA), and gray-market purity is a concern.
Sold 'for research use only,' with no FDA-sanctioned human dose. Athletes should be aware it is explicitly on the WADA prohibited list.
Perceived whole-body recovery and mobility; synergy in blends.
NOT FDA-approved. Removed from Category 2 (Apr 2026); under PCAC review Jul 23, 2026 (FDA proposing NOT to list). Prohibited in sport. Verify.