Human VTB (Human vitronectin-Thymosin b4 fusion) is constructed by fusion Vitronectin (62-398 domain) with full length Thymosin b4 at its C-terminal. Human Vitronectin is a liver derived major plasma glycoprotein that exhibits multiple activities and functions as a cell adhesion molecule and regulator of coagulation. Human Thymosins are small polypeptides originally isolated from the thymus, but most are actually present in many other tissues. The archetypical b-Thymosin is Thymosin-b4, which is a cellular constituent in many tissues. In addition to its role as a major actin-sequestering molecule, Thymosin-b4 has a role in tissue repair. Such effects have been shown in animal models of tissue damage and now in human clinical trials. Recently, Recombinant Vitronectin NC terminal domain (62-398aa) has been developed as coating matrix protein for sustaining human ES or iPS cell culture(1 & 2) and Thymosin-b4 was shown to stimulate regeneration of adult cardiac progenitor cells in a paper published in Nature (3).

To develop a unique coating matrix protein for sustaining ES cell culture and benefiting ES to cardiac progenitor differentiation, recombinant human vitronectin (62–398aa) domain and full-length human Thymosin-b4 fusion protein cDNA were expressed in E. coli as inclusion bodies, refolded using our unique “temperature shift inclusion body refolding” technology and chromatographically purified. Coating this recombinant VTB protein in proper ES cell or cardiomyocytes culture medium(1) at concentration 0.5ug – 1ug per 1 cm2 may benefit for culture of human ES cell and differentiation cardiac progenitor differentiation in vitro.

1. Purity: > 95% by SDS-PAGE.

2. Endotoxin: < 30 EU per 1 µg of the protein by the LAL method.

3. Biological Activity: When coated onto tissue culture plastic, VTB fusion protein promotes one half maximal attachment of human cardiomytes cells in serum-free medium at < 0.1 µg / cm2. Maximum attachment should occur at approximately 0.5 µg / cm2.