Cell-binding Domain Context Affects Cell Behavior on Engineered Proteins

A family of artificial extracellular matrix proteins developed for application in small-diameter vascular grafts is used to examine the importance of cell-binding domain context on cell adhesion and spreading. The engineered protein sequences are derived from the naturally occurring extracellular matrix proteins elastin and fibronectin. While each engineered protein contains identical CS5 cell-binding domain sequences, the lysine residues that serve as cross-linking sites are either (i) within the elastin cassettes or (ii) confined to the ends of the protein. Endothelial cells adhere specifically to the CS5 sequence in both of these proteins, but cell adhesion and spreading are more robust on proteins in which the lysine residues are confined to the terminal regions of the chain. These results may be due to altered protein conformations that affect either the accessibility of the CS5 sequence or its affinity for the alpha(4)beta(1) integrin receptor on the endothelial cell surface. Amino acid choice outside the cell-binding domain can thus have a significant impact on the behavior of cells cultured on artificial extracellular matrix proteins.