Macro- or Microfiber Scaffolds with Different Fiber Arrangements: Determining the Best Design for Osteogenesis

Bone tissue engineering scaffolds with varied 3D structures have been investigated extensively. The arrangements and diameters of scaffold fibers are usually considered during the scaffold manufacturing processes. There is still controversy over the optimal angle of arrangement and fiber diameter of scaffolds for bone tissue engineering. To highlight the problem, we herein designed macrofiber (diameter: 551.3 ± 22.11 μm) and microfiber (diameter: 10.8 ± 0.85 μm) scaffolds with fibers arranged at 90, 60, 30, and 15°. Physicochemical characterization revealed that macrofiber scaffolds had better mechanical properties and hydrophilicity than microfiber ones. Although the different fiber arrangements of the macrofiber scaffold showed no significant differences in alkaline phosphatase expression and calcium nodule deposition, the macrofiber scaffold enhanced new bone formation obviously in the skull defect model. The microfiber scaffolds with deposition angles of 90 and 60° efficiently promoted cell osteogenic differentiation by regulating the YAP pathway and enhancing the expression of Runx2 and OCN. However, microfiber scaffolds seemed to be a barrier to new bone formation when applied for bone tissue repair of skull defects. Poor mechanical properties severely limited the biological application of microfiber scaffolds. The macrostructures guaranteed sufficient mechanical strength for osteogenic space maintenance. For clinical application, macrofiber scaffolds with high mechanical strength might be a promising therapy for repairing large bone tissue defects.