Thymosin beta-4 

it is a naturally-occurring peptide found in all cells in the body, except for red blood cells (erythrocytes). Thymosin beta-4 contains 43 amino acids and has a mass of 4.9 kDa. In humans, this peptide binds to the G-actin cytoskeleton to promote cellular migration, proliferation, and differentiation.¹ Thymosin beta-4 is also found in high concentrations at wound sites, highlighting its healing role. It is released by platelets and macrophages, which are the first cells to respond during injury.² Due to its mobilizing properties and functions in healing and angiogenesis, thymosin beta-4 has been studied extensively in in vitro and in vivo models of cardiac injury caused by ischemia, stroke, ischemic limbs, liver fibrosis, and corneal injury.² Both chemically-synthesized and recombinant versions of this peptide are used in these studies. One study using a mouse model of coronary ligation found that thymosin beta-4 interacts with Akt and integrin-linked kinase (ILK) to improve heart function by promoting cardiomyocyte mobility and survival.¹ Similar properties were observed in embryonic hearts, where a migration phenotype and improved survival are seen, even in postnatal cardiomyocytes.¹ In an in vitro model of liver fibrosis using hematopoietic stem cells (HSCs), the addition of exogenous thymosin beta-4 blocked the proliferation of activated HSCs, which may contribute to decreased fibrosis. However, the authors noted that endogenous thymosin beta-4 appeared to have the opposite effect, highlighting the need for more studies using exogenous peptides.³ In a model of corneal injury, thymosin beta-4 promotes cell migration and differentiation to the cornea to facilitate wound repair. This is important because the cornea is an avascular tissue that can be difficult to heal without causing fibrosis.⁴

Thymosin beta-4 is available as a white lyophilized powder in a 5 mg vial.