Biomimetic Elastic Bacterial Cellulose/Polyurethane Micro-Nano Fibrous Grafts for Small-Diameter Vascular Replacement: Fabrication and Evaluation

No breakthrough has yet been achieved in developing small-diameter vascular grafts for clinical application. Mimicking both the native intimal architecture and the physiological elasticity of natural blood vessels is widely regarded as a highly promising strategy. Polyurethane (PU) is a mechanically suitable candidate for vascular grafts owing to its molecular tunability and intrinsic elasticity. However, conventional PU materials often suffer from inadequate biocompatibility and insufficient elastic stability. To address these challenges, we have developed a PU elastomer that demonstrates exceptional resistance to degradation and alkali solutions. Subsequently, a micronano fibrous graft integrating bacterial cellulose nanofibers (BC) with PU microfibrous (PUF) film was fabricated using a combined weaving and in situ biosynthesis approach. The resulting micronano composite fibrous film exhibits excellent elastic stability in simulated physiological fluids. Moreover, incorporation of BC significantly enhances the hydrophilicity, hemocompatibility, and cytocompatibility of the PUF. Importantly, this unique micronano architecture upregulates the expression of CD31 and VEGF, thereby promoting endothelial cell adhesion and proliferation. The bridging structure of BC nanofibers over the rough PU microfibers further facilitates cell migration. These findings suggest that the BC/PUF composite holds significant promise as an artificial graft material capable of supporting the rapid formation of an endothelial cell monolayer.