A biomimetic three-dimensional porous scaffold of mineralized recombinant collagen-sodium alginate for efficiently repairing critical-size cranial defects

The reconstruction of critical-size bone defects caused by trauma, tumor resection, and congenital anomalies remains a fundamental challenge in tissue engineering. Biomimetic scaffolds have received extensive attention for the discovery of advanced artificial bone substitutes due to their inherent biocompatibility and biodegradability. Herein, we have for the first time developed a biomimetic three-dimensional porous scaffold of mineralized recombinant collagen-sodium alginate (MRCSA) with supreme healing efficacy for critical-size cranial defects. In situ biomineralization using recombinant collagen as the unique biotemplate results in the formation of nano-hydroxyapatite with well-ordered mineralized recombinant collagen with fibrous morphology. The MRCSA scaffold finely mimics the organic-inorganic composition and the uniform porous nanostructures of natural bone, which exhibits excellent biocompatibility, adequate biodegradability, superior cellular activity, and exceptional osteogenic differentiation capability. Magnetic resonance imaging (MRI), Micro-computed tomography (micro-CT), and histological characterization of rat models of critical-size cranial defects have consistently demonstrated that the MRCSA scaffold has regenerated an abundance of new bones to refill the defect sites with much higher bone mineral density, bone volume/total volume as well as trabeculae. The novel biomimetic scaffold provides a remarkably improved remedy of critical-size cranial defects, suggesting very promising applications in orthopedics and plastics.