Extracellular matrix (EMC) and growth factor signaling environments are part of the nature mechanism for regulating stem cell fate. These micro-environmental stimuli are processed through a veritable network of intracellular signaling pathway. Evidence to date suggests that understanding of interactions between these pathway in defined cell culture condition are critical in controlling cell fate in vitro in the development of cell based therapeutic applications. Laminins are high-molecular weight (>400kD) protein of the extracellular matrix. The laminins are an important and biologically active part of the basal lamina, influencing cell differentiation, migration and adhesion. Currently many active domain (peptide) from various laminins have been identified, which provide a opportunity for protein – engineering for its production.

To develop a specific coating matrix protein for representing human laminin a3, two active peptide domain from human laminin a1, were joint together with small linker and then fusion with human vitronectin (62-398aa). As human vitronectin provides an excellent polystyrene surface binding capacity, this recombinant VTN-laminin peptide fusion might serve as a unique coating matrix for various stem cell differentiation applications in vitro.

Two active peptide fusion fragments of human laminin a1 (86aa) was further fused to human vitronectin protein (62- 398aa with flexible linker domain GGGS in between) to generate a fusion protein, Named as VTN- LAMAα3. This VTN-LAMAα3 peptide cDNA was constructed with codon optimization gene synthesis technology. This protein was expressed in E. coli as inclusion bodies. The final product was refolded using our unique “temperature shift inclusion body refolding” technology and chromatographically purified.