The use of microfiber composites of elastin-like protein matrix reinforced with synthetic collagen in the design of vascular grafts

Collagen and elastin networks contribute to highly specialized biomechanical responses in numerous tissues and species. Biomechanical properties such as modulus, elasticity, and strength ultimately affect tissue function and durability, as well as local cellular behavior. In the case of vascular bypass grafts, compliance at physiologic pressures is correlated with increased patency due to a reduction in anastomotic intimal hyerplasia. In this report, we combine extracellular matrix (ECM) protein analogues to yield multilamellar vascular grafts comprised of a recombinant elastin-like protein matrix reinforced with synthetic collagen microfibers. Structural analysis revealed that the fabrication scheme permits a range of fiber orientations and volume fractions, leading to tunable mechanical properties. Burst strengths of 239–2760 mm Hg, compliances of 2.8–8.4%/100 mm Hg, and suture retention strengths of 35–192 gf were observed. The design most closely approximating all target criteria displayed a burst strength of 1483 ± 143 mm Hg, a compliance of 5.1 ± 0.8%/100 mm Hg, and a suture retention strength of 173 ± 4 gf. These results indicate that through incorporation of reinforcing collagen microfibers, recombinant elastomeric protein-based biomaterials can play a significant role in load bearing tissue substitutes. We believe that similar composites can be incorporated into tissue engineering schemes that seek to integrate cells within the structure, prior to or after implantation in vivo.