Experimental study of rhBMP-2 chitosan nano-sustained release carrier-loaded PLGA/nHA scaffolds to construct mandibular tissue-engineered bone

Objectives: To develop PLGA/nHA scaffold containing BMP-2 cell growth factor chitosan sustained release system as tissue engineered bone for repairing large jaw defects, test its sustained release rhBMP-2 efficiency in vitro, and evaluate its Osteogenesis in rabbit mandibular defects. Methods: Tissue engineered bone scaffold complexes were prepared by complexing rhBMP-2 loaded chitosan (CS / rhBMP-2) nano sustained release carrier with PLGA / nHA scaffold carrier by 3D printing. In vitro, the porosity, pore size and degradation rate and the dose-time effect relationship of cytokine release were examined. Micro-CT, hematoxylin/eosin staining, Masson staining and immunohistochemistry were determined at week 4, week 8 and week 12 in 18 rabbits. Results: In vitro, the porosity was (73.64 +/- 1.82)%, and the average pore diameter was (431.31 +/- 18.40) mu m. The cumulative release was only 9.54 +/- 0.86% within 48 h and 61.38 +/- 2.39% on the 30th day. In vivo, Micro-CT examination showed that the BMD and the bone volume fraction at 4, 8, and 12 weeks were higher in the implantation group than in the control group. In the 12th week, Masson staining showed that new bone occupied 19.2% of the defect area in the control group, whereas the proportion of new bone reached 45.5% in the experimental group. Conclusions: PLGA/nHA/CS/rhBMP-2 scaffold complex effectively controlled the early burst effect of rhBMP-2. The bone tissue engineering scaffold complex had good biocompatibility and induced osteogenic effects. It successfully repaired the experimental bone defect area of the rabbit mandible.