Silk Fibroin/Collagen/Hydroxyapatite Scaffolds Obtained by 3D Printing Technology and Loaded with Recombinant Human Erythropoietin in the Reconstruction of Alveolar Bone Defects.

The fast osteogenesis of the large alveolar fossa and the maintenance of the height of the alveolar ridge after tooth extraction have always been a clinical challenge. Therefore, this work describes the creation of innovative silk fibroin/collagen/hydroxyapatite (SCH) biological scaffolds by 3D printing technology, which are loaded with recombinant human erythropoietin (rh-EPO) for the reconstruction of bone defects. Low-temperature 3D printing can maintain the biological activity of silk fibroin and collagen. The SCH scaffolds showed the ideal water absorption and porosity, being a sustained-release carrier of rh-EPO. The optimized scaffolds had ideal mechanical properties in vitro, and MC3T3-E1 cells could easily adhere and proliferate on it. In vivo experiments in rabbits demonstrated that the composite scaffolds gradually degraded and promoted the accumulation and proliferation of osteoblasts and the formation of collagen fibers, significantly promoting the reconstruction of mandibular defects. In this study, a novel composite biological scaffold was prepared using 3D printing technology, and the scaffold was innovatively combined with the multifunctional growth factor rh-EPO. This provides a new optimized composite material for the reconstruction of irregular mandible defects, and this biomaterial is promising for clinical reconstruction of alveolar bone defects.

Effects of Fiber Cross-Angle Structures on the Mechanical Property of 3D Printed Scaffolds and Performance of Seeded MC3T3-E1 Cells.

The three-dimensional (3D) printing technology combined with bone tissue engineering has become one of the major methods for mandibular reconstruction. However, the key factor retarding mandible reconstruction is the barrier of understanding and achieving the complex 3D gridwork formed by the trabeculae. This study innovatively constructed a low-temperature 3D printing silk fibroin/collagen/hydroxyapatite (SF/COL/HA) composite scaffold with a stable structure and remarkable biocompatibility. We designed three kinds of six-layer scaffolds with mixed fiber cross-angle structures (FCAS) of [0°/90°/0°/90°/0°/90°], [0°/45°/90°/135°/180°/225°] and [0°/30°/60°/90°/120°/150°]. Material properties of these scaffolds such as porosity, water absorption rate, X-ray diffraction, Fourier transform infrared spectroscopy, and compression performance were detected. Then, the MC3T3-E1 cells were seeded on these scaffolds and the adhesion, proliferation, and differentiation were investigated. To be more convincing, the same experiments were performed on another polycaprolactone/hydroxyapatite scaffold. The results suggested that the changes of FCAS affected the mechanical properties of 3D printed scaffolds and performance of seeded cells. Besides, the 90° FCAS significantly enhanced the compressive modulus in two groups and were more conducive to the cell proliferation and osteogenesis, which provided evidence for exploring the influence of FCAS on the properties of scaffolds and the application of two composite scaffolds in tissue regeneration.