Preparation and characterization of flexible and elastic porous tubular PTMC scaffolds for vascular tissue engineering

Vascular grafts with an inner diameter less than 6 mm are urgently needed due to the increasing prevalence of vascular disease. In this study, tubular scaffolds for vascular tissue engineering were fabricated by photo-crosslinking of acrylate-functionalized poly(trimethylene carbonate) (PTMC) macromers of different molecular weights in a glass mold. Porous structures were prepared by means of salt leaching. Tubular scaffolds were obtained with an inner diameter of 3 mm, a wall thickness of 1 mm, and a length of 4.5 cm. Pore sizes ranged from 0 to 290 µm, and the porosity was around 70%. The pores were homogeneously distributed and interconnected. PTMC macromers with a molecular weight of 4, 8, 13, 17, and 22 kg/mol were used. With increasing PTMC macromer molecular weight from 4 to 22 kg/mol, the E-modulus and maximum tensile strength of the scaffolds in the radial direction increased from 0.56 to 1.12 MPa and 0.12 to 0.55 MPa, respectively. Stress–strain curves for scaffolds made of 13, 17, and 22 kg/mol PTMC macromers showed a “toe” region characteristic for native arteries, followed by a linear increase until the maximum stress was reached. The E-moduli of the latter scaffolds are comparable to those of native arteries, whereas the maximum tensile strengths are approximately fourfold lower. This can be improved, however, by cell seeding in the porous scaffolds and subsequent mechanical stimulation in a bioreactor. It is concluded that the porous tubular scaffolds made of 13, 17, and 22 kg/mol PTMC macromers are suitable scaffolds for vascular tissue engineering