Mechanical properties of artificial protein matrices engineered for control of cell and tissue behavior

Genetic engineering methods were used for the preparation of artificial proteins containing sequences designed to reproduce essential features of the extracellular matrix (ECM). The long-term objective of the work is to develop matrices for use in the engineering of small-diameter vascular grafts. The CS5 domain of fibronectin provides binding sites for vascular endothelial cells, while an elastin-like repeat, [(VPGIG)(2)(VPGKG)(VPGIG)(2)], controls the mechanical properties and includes sites for covalent cross-linking. Bis(sulfosuccinimidyl) suberate and disuccinimidyl suberate were used to cross-link artificial ECM protein films for uniaxial tensile testing. Variation in the amount of cross-linker and protein weight fraction allowed preparation of films with Young's moduli ranging from 0.07 to 0.97 MPa. The weight fraction of protein in the hydrated, cross-linked films was measured to be between 0.2 and 0.4; the molecular weight between cross-links (M-c) varied from 3000 to 38 000. The moduli and M, of the films span the ranges reported for natural elastins.