The Peptide Atlas
TB-500 (Thymosin Beta-4)
A synthetic version of thymosin beta-4, a 43-amino-acid protein found in almost every cell, concentrated where the body is repairing itself. Products sold as TB-500 are the full peptide or a short active fragment of it.
Class
Repair peptide (actin-regulating)
Evidence
Early research
Status
Studied in research settings.
Forms
Studied as injection; eye drops in ophthalmic trials
What people use it for
Injury and soft-tissue recovery, often stacked with BPC-157.
The signal
After an injury, cells at the damage site reorganize their internal scaffolding to move, cover the wound, and rebuild. Thymosin beta-4 regulates actin, the protein that scaffolding is made of, which puts it near the center of how repair cells get where they need to go.
How it works
In lab research it promotes the migration of repair cells into damaged tissue and supports new blood-vessel growth [1], with the earliest wound-healing results published in 1999 [2].
What the research shows
The animal wound-healing literature is substantial and consistent. Human trials exist in one area: thymosin beta-4 eye drops have been through randomized trials for severe dry eye, with improvements in signs and symptoms [3]. For the injury-and-recovery use most people mean by TB-500, there are no published human trials, so that use rests on animal data.
What people get wrong
That it's a growth-hormone-related peptide (the name sounds like the secretagogues, but it has nothing to do with growth hormone). And that the eye-drop trial results transfer to injections for muscle or tendon injuries. Different route, different use, different evidence.
References
- Malinda KM et al., FASEB J (1997). Thymosin beta 4 stimulates directional migration of human umbilical vein endothelial cells. PubMed
- Malinda KM et al., J Invest Dermatol (1999). Thymosin beta4 accelerates wound healing. PubMed
- Sosne G et al., Cornea (2015). Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial. PubMed
Last reviewed 2026-08-24. Every reference is verified against the primary literature at review time. How the Atlas grades evidence