Thymosin beta-4 (Tβ4) is a natural protein made of 43 amino acids, found throughout the body. Researchers describe it as playing a role in cell movement and wound repair.[1]
Unlike most peptides in this glossary, Tβ4 has real human trial history. Researchers tested a topical eye-drop form of Tβ4, called RGN-259, in human trials for dry eye and corneal healing.[2]
That trial history is limited to the eyes, and to a topical drop — not an injection. No published human trial has tested Tβ4 for tendon, muscle, or joint healing. The peptide sold as TB-500 is only a small fragment of this protein, and it does not inherit Tβ4’s dry-eye trial results — that data was never generated for the fragment itself.