Sustained Release of Bone Morphogenetic Protein 2/Chitosan‐Collagen Scaffold Repairs Rabbit Knee Joint Cartilage Defects

To explore the effects of a collagen‐binding domains‐bone morphogenetic protein 2 (CBD‐BMP‐2) scaffold on repairing cartilage defects. A chitosan‐collagen scaffold was prepared and its physicochemical properties were evaluated. A plasmid encoding the CBD and BMP‐2 was constructed, a CBD‐BMP‐2 composite scaffold was prepared, and the controlled release of BMP‐2 was assessed in vitro. Knee cartilage defect model rabbits were divided into the control, CBD, and CBD‐BMP‐2 groups ( n = 9). Gross observation, MRI, staining, and IHC were performed to evaluate the cartilage repair outcomes. CBD‐BMP‐2 composite scaffold provided sufficient support and promoting cell attachment and proliferation. It consistently released BMP‐2 for over 30 days in vitro. It significantly enhanced cartilage regeneration and repair. After surgery, cartilage growth in the CBD‐BMP‐2 group was superior to the control and CBD groups. The CBD‐BMP‐2 group demonstrated better coverage of new cartilage tissue. In the CBD‐BMP‐2 group, new cartilage tissue was tightly structured and cells were neatly arranged, and there were a rich cartilage matrix and dense collagen fibers. Type II collagen expression was significantly increased in the CBD‐BMP‐2 group. CBD‐BMP‐2 composite scaffold has excellent physicochemical properties and controlled‐release functionality, providing superior repair effects for rabbit knee joint cartilage defects.