Extensive work by many groups has focused on searching for ideal substitute materials for cardiovascular applications for vascular bypass or replacement of obstructed blood vessels due to diseases or trauma during the last half-century. While large (>10mm ID) and medium (6-10 mm ID) -diameter vascular grafts are already commercially available (expanded poly(tetrafluoro ethylene) (ePTFE) or poly(ethylene terephthalaate) (PET), better known as Dacron)1, considerable challenges remain in the development and application of small diameter (< 6mm ID) vascular grafts due to its high failure rates owing to a thrombosis, chronic anastomotic, and intimal hyperplasia2. Thus, it is imperative to find a solution targeted to the fabrication of small-diameter vascular grafts.In this study, we employed amino acid-based poly(ester urea) (PEU) as the base material for small diameter vascular graft fabrication due to its excellent elasticity, bio-resorption characteristics, tunable mechanical properties, degradation rate, etc3. The technique used to fabricate the grafts was electrospinning, so that the fibrous nanostructure can mimic the structure of the native extracellular matrix1.The grafts have a length of ~ 3 cm with a wall thickness ranging from 50 um to 200 um. SEM images of the grafts showed randomly oriented fibers with diameters of 1.0�0.7 um and pore sizes of 25.7�11.1 um2. This morphology provides a favorable environment for the growth of vascular cells. Uniaxial tensile test of the grafts showed the tensile strength was ~12.5 MPa, elongation at break was ~300%, and Young's modulus was 1.6�0.3 MPa, which was similar to the tensile property of native tissues. Burst pressure test showed that the grafts can endure 1000 mmHg under continuous flow for 30 min without leaking, demonstrating that the grafts possess excellent physical strength and can be developed as substitutes for native blood vessels. A preliminary animal study on SCID mice showed no acute thrombosis and no graft rupture in 24 hs. The grafts continue to perform well in mice after 2-month implantation. Fabrication of vascular grafts with asymmetric functionalization by incorporating special bioactive molecules is also ongoing.  1) Walpoth, B. H.; Bowlin, G. L. Expert Rev Med Devices 2005, 2, 657-665.2)Seifalian, A. M.; Tiwari, A.; Hamilton, G. and Salacinski, H. J. Artif Organs, 2002, 26, 307-320.3) Stakleff, K. S.; Lin, F.; Callahan, L. A. S.; Wade, M. B.; Esterle, A.; Miller, J.; Graham, M.; Becker, M. L. Acta Biomaterialia, 2013, 9, 5132-5142.

Electrospinning of resorbable, amino acid-based poly(ester urea)s for small diameter vascular graft

247th National Meeting (2014)

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