Anisotropic electrospun poly(ε-caprolactone)/polycarbonate urethane scaffolds with improved fatigue performance for tissue-engineered heart valves

In this study, poly(ε-caprolactone) (PCL) and polycarbonate urethane (PCU) were used to fabricate electrospun scaffolds for tissue-engineered heart valves (TEHVs). The PCL/PCU scaffold containing 25 % PCU (named as 75%PCL-O) with oriented fibers exhibited pronounced anisotropy, with elastic moduli of 53.47 ± 0.93 MPa (X-axis) and 4.19 ± 0.70 MPa (Y-axis), and tensile strength of 14.21 ± 1.16 MPa (X-axis) and 1.59 ± 0.09 MPa (Y-axis), respectively, close to native heart valves. The 75%PCL-O scaffold showed good cell viability and guided cell alignment along the fibers, and no obvious hemolysis or thrombus formation. Hydrodynamic tests showed an effective orifice area (EOA) of 2.42 ± 0.12 cm² and a regurgitant fraction (RF) of 5.98 ± 2.31 % for a 25 mm surgical pulmonary valve, meeting the ISO 5840-2 standard. The accelerated fatigue testing demonstrated that the EOA and RF remained stable throughout 50 million cycles. Additionally, finite element analysis (FEA) revealed that mechanical stress concentrated at the free edge for the 75%PCL-O valve leaflet during the opening-closing cycles, correlating well with the observed fiber degradation in these regions during fatigue tests. In summary, the 75%PCL-O scaffold exhibits favorable mechanical performance, good biocompatibility and improved durability, showing great potential for TEHV applications.