Electrospun anisotropic fiber reinforced composites for artificial heart valves

Anisotropic composite valves that approximate natural heart valves are essential for the successful construction of tissue-engineered heart valves. In this work, anisotropic nylon (polyamides, PA) fiber membranes were prepared via electrospinning and further composited with thermoplastic polyurethane (TPU) by the impregnation method to obtain anisotropic PA/TPU composite valves. Young's modulus of the PA/TPU composite valves in the axial and radial directions along the fibers was 85.07 +/- 4.22 MPa and 28.72 +/- 1.16 MPa, respectively. The anisotropic PA/TPU composite valve exhibited excellent anisotropy, and its anisotropy ratio was 3.03, which was close to that of natural valves. Besides, the anisotropic PA/TPU composite valve exhibits high transparency (similar to 87%). The in vitro experiments revealed that anisotropic PA/TPU composite valves have better resistance to calcification and good blood compatibility compared with anisotropic nylon fiber membranes. Moreover, the hydrophilicity presented by the anisotropic PA/TPU composite valve reduced the adhesion of calcified particles. The good anticoagulant properties exhibited by the anisotropic PA/TPU composite valve effectively reduced the formation of thrombus after implantation. Cellular experiments and subcutaneous implantation experiments in rats showed that anisotropic PA/TPU composite valves exhibit cellular nontoxicity and good biocompatibility, contributing to cellular differentiation and growth. This preparation method has great potential in preparing anisotropic composite valves.