Heparin-loaded silk fibroin microparticles/bacterial nanocellulose (Hep@SFMPs/BNC) conduits for application as small-caliber artificial blood vessels.

Small-caliber artificial blood vessels are highly demanded and face challenges, including thrombosis and intimal hyperplasia. The excellent properties of bacterial nanocellulose (BNC) make it an excellent material for preparing artificial blood vessels. Heparin (Hep)-loaded silk fibroin microparticles (SFMPs) were synthesized in situ within the conduit wall via liquid pressure injection and phase separation, aiming to improve BNC's anticoagulant properties. SFMPs served as a carrier for Hep, enabling its sustained slow release from the BNC conduits, and the Hep@SFMPs/BNC promoted the adhesion and proliferation of vascular cells. In vitro blood experiments and gene expression analysis of HUVECs showed that the composite conduits had a decreased coagulation rate, fewer platelets adsorbed, and lower levels of inflammation compared with BNC conduits. After 5 months of abdominal aortic replacement in rats, an in situ formation of a continuous endothelial layer was observed, covering 90 % of the surface with endothelial cells. The proposed preparation method is simple, efficient, and requires fewer reagents, with the added benefit of eliminating the need for crosslinking agents. The Hep@SFMPs/BNC conduit has the characteristics of anticoagulant and endothelial growth-promoting properties, with strong evidence from animal experiments supporting the potential of Hep@SFMPs/BNC conduits as small-caliber artificial blood vessels.