Shellac: a bioactive coating for surface engineering of cardiovascular devices

Neointimal hyperplasia and thrombosis are the main factors contributing to implantation failure of blood-contacting devices. Here, the excellent potential of shellac (lac), a naturally-sourced, non-toxic, and biodegradable resin, as a multifunctional coating to address these critical issues in blood-contacting devices is reported. Shellac coatings with varied thicknesses of 95.1–518.6 nm are fabricated using spin coating. The viability and proliferation of endothelial cells and smooth muscle cells cultured on the coatings with a relatively low thickness (95.1 nm) have no significant difference compared with that of 316L stainless steel (316L SS), while the viability and proliferation of the cells decrease significantly for the shellac coatings with thicknesses higher than 308.5 nm. Hemolysis ratios for all shellac coatings are less than 5%. The results of anticoagulation tests manifest that shellac coatings show superior anticoagulant performance compared with 316L SS through inhibiting coagulation pathways. Through implantation in the abdominal aorta of rats, it is shown for the first time that shellac coatings can inhibit neointimal hyperplasia, most likely due to the inhibition of vascular smooth muscle cell phenotypic transformation. Bio-resin, multifunctional shellac coatings studied here, can be easily administered from ethanol solutions onto almost any type of solid material, ushering a new dimension for surface engineering of cardiovascular devices such as inferior vena cava filters and stents.