Thymosin b4 is a naturally occurring actin-sequestering peptide produced by cells of the human bone marrow. It is found at high concentrations within thymus and spleen cells as well as a variety of other cell types and is known to affect the organization of the actin cytoskeleton.
TB-4 has been shown to promote tissue repair and regeneration including enhanced wound healing, accelerated scar recovery, improved hair growth, and stronger tendons and ligaments. It also reduces the severity of traumatic injuries to tissues and organs such as the brain, heart, eyes, and muscles. In addition, it has been shown to prevent or slow the progression of liver fibrosis, and enhances recovery following hepatic injury.
Thymosin B4 (TB-4), the largest member of the b-thymosin family, is the most abundant in mammalian tissues and cells, where it acts as the main G-actin sequestering peptide. TB-4 binds monomeric actin in a 1:1 complex, acting as an actin buffer to prevent its polymerisation into filaments, while supplying a pool of actin monomers that can be rapidly accessed by the cell when required.
Studies have shown that exogenous thymosin b4 is capable of preventing or retarding the development of hepatic fibrosis, a major characteristic of chronic liver disease, by suppressing the induced expression of key proteins such as matrix metalloproteinases, tumor necrosis factor-a, interleukin-1b, and transforming growth factor-beta1. Additionally, it has been demonstrated to enhance the apoptosis of hepatic stellate cells, a primary source of collagen deposition in hepatic fibrosis, through the induction of caspase-3.