Bilayer nicorandil-loaded small-diameter vascular grafts improve endothelial cell function via PI3K/AKT/eNOS pathway

For the surgical treatment of cardiovascular disease (CVD), there is a clear and unmet need in developing small-diameter (diameter < 6 mm) vascular grafts. In our previous work, sulfated silk fibroin (SF) was successfully fabricated as a potential candidate for preparing vascular grafts due to the great cytocompatibility and hemocompatibility. However, vascular graft with single layer is difficult to adapt to the complex internal environment. In this work, polycaprolactone (PCL) and sulfated SF were used to fabricate bilayer vascular graft (BLVG) to mimic the structure of natural blood vessels. To enhance the biological activity of BLVG, nicorandil (NIC), an FDA-approved drug with multi-bioactivity, was loaded in the BLVG to fabricate NIC-loaded BLVG. The morphology, chemical composition and mechanical properties of NIC-loaded BLVG were assessed. The results showed that the bilayer structure of NIC-loaded BLVG endowed the graft with a biphasic drug release behavior. The in vitro studies indicated that NIC-loaded BLVG could significantly increase the proliferation, migration and antioxidation capability of endothelial cells (ECs). Moreover, we found that the potential biological mechanism was the activation of PI3K/AKT/eNOS signaling pathway. Overall, the results effectively demonstrated that NIC-loaded BLVG had a promising in vitro performance as a functional small-diameter vascular graft.