TB-500
Synthetic analog of the actin-binding domain of Thymosin Beta-4; promotes cell migration, angiogenesis, and modulation of inflammation in regenerating tissue.
TB-500 is the marketed name for a synthetic heptapeptide (sequence LKKTETQ) corresponding to the active actin-binding region of Thymosin Beta-4 (Tβ4), a 43-amino-acid protein that is the most abundant member of the beta-thymosin family in mammals. Tβ4 is constitutively expressed in nearly every cell and is released systemically following injury.
The research interest in TB-500 is driven by Tβ4’s role in regulating G-actin polymerization. By sequestering monomeric actin, Tβ4 (and by extension the TB-500 fragment) modulates the cytoskeleton in ways that facilitate cell motility, a prerequisite for the migration of fibroblasts, endothelial cells, and keratinocytes into wound sites. Downstream effects observed across studies include accelerated re-epithelialization, increased collagen deposition, improved angiogenic response, and attenuation of fibrotic remodeling. In cardiac infarction models, Tβ4 administration is associated with improved post-ischemic function attributed to both anti-apoptotic signaling and progenitor-cell recruitment.
The TB-500 fragment retains a subset of Tβ4’s actin-binding activity and shows similar but not identical effects in regenerative models. Most preclinical work uses Tβ4 itself rather than the TB-500 fragment; comparative pharmacokinetic data is limited. Both molecules remain investigational and are not approved for human therapeutic use.