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.