Constructing Hierarchical Porous Bacterial Cellulose Outer Layer for Enhanced SMCs Infiltration in a Double-Layered Vascular Graft

Natural blood vessels possess a multi-layered structure. Herein, we present a bio-inspired double-layered integrated tubular graft with a compact inner layer and a porous outer layer. The inner layer consists of nanofibrous bacterial cellulose (BC) and microfibrous cellulose acetate (CA), which favors the adhesion and proliferation of endothelial cells (ECs). The outer layer, with hierarchical pores including nano-sized pores from pristine BC, median-sized pores (dozens of microns) created by particle leaching, and a large pore (hundreds of microns) array created by laser ablation, is appropriate for the penetration of vascular smooth muscle cells (SMCs). The in-situ biosynthesis was employed to "suture" the two layers, aiming to achieve an integrated tubular structure. The morphology, mechanical properties, and cell behavior of the tubular grafts were characterized. The in vitro study demonstrates that the unique outer layer possesses enhanced SMC penetration compared to the counterpart without hierarchical pores. Overall, the findings of this study demonstrate the potential of such a biomimetic integrated vascular graft for vascular replacement and regeneration.