Staggered Nanofiber Scaffolds via Electric-Field-Controlled Assembly for Bone Tissue Regeneration

Nanofibers fabricated by a typical electrospinning technology cannot simulate the highly ordered structure of the natural extracellular matrix, which restrict their applications in tissue engineering. Here, an electrospinning device is developed that utilizes auxiliary electrodes to regulate the electric field distribution and small-diameter rods to collect nanofibers with a controllable alignment. Electrospun nanofibers at different oblique angles are obtained and precisely assembled into osteon-mimetic structures: a longitudinally aligned nanofibrous tube as a vascular channel and an outer layer of staggered nanofibers mimicking bone collagen fibril networks. Physicochemical characterization demonstrates that the specially aligned scaffolds possess enhanced mechanical properties, suitable hydrophilicities, and long-term biological stabilities. In vitro bioassessment reveals that a parallel arrangement of nanofibers can induce angiogenic differentiation of human umbilical vein endothelial cells and staggered-aligned topography can enhance the expression of osteogenesis-related proteins and marker genes in MG63 cells. This study for the first time creates staggered nanofiber scaffolds by electrospinning and confirms their topography-based inductive effect on cell fate. The osteon-mimetic nanofiber scaffolds, which could induce angiogenesis and osteogenesis through nanotopographic cues without any biological factors, have great potential as biomaterial matrices for vascularized bone regeneration.