Thymosin Beta-4 (Tβ4), also called TB-500 is a synthetic version of natural peptide consisting of 43 amino acids. This naturally occurring peptide plays a vital role in repairing and regeneration of injured cells and tissues by reducing apoptosis, inflammation, and microbial growth after injury.

It is released by various cell types, including platelets and macrophages, and binds to actin, promoting cell migration and differentiation of stem/progenitor cells to form new blood vessels and regenerate tissue. It was studied also for wound healin.