ABSTRACT
BACKGROUND: Preliminary experiments have confirmed that poly(hydroxybutyrate-co-hydroxyoctanoate) (PHBHOx)/collagen composite osteochondral scaffold exhibits desirable pore structure and biocompatibility. OBJECTIVE: To investigate the effect of PHBHOx/collagen composite osteochondral scaffold carrying bone marrow mesenchymal stem cells in the repair of articular osteochondral defects in the weight-bearing area of rabbits. METHODS: Cone-shaped osteochondral defects were created in the femoral medial condyle of the right knee of 30 New Zealand white rabbits. Then, the rabbit models were randomized into three groups and underwent implantation of PHBHOx/collagen composite osteochondral scaffold carrying bone marrow mesenchymal stem cells in the scaffold-cell group, PHBHOx/collagen composite osteochondral scaffold in the scaffold group and no intervention in the control group. At 4 and 12 weeks after surgery, animals were sacrificed for gross, Micro-CT, histological and immunohistochemical collagen II observations. RESULTS AND CONCLUSION: At 12 weeks after surgery, Micro-CT scanning results suggested that osteochondral defects were not repaired in the control group, repaired incompletely in the scaffold group with many new bone trabeculae, and repaired completely in the scaffold-cell group. Histological results showed that at 4 weeks after surgery, the defects in the control group were filled with amorphous tissues, subchondral bone formation just occurred in the scaffold group but increased in the scaffold-cell group. At 12 weeks after surgery, trabecular bone structure with no cartilage lacuna was observed in the control group; incomplete subchondral bone formation was observed in the scaffold group, and the cartilage layer was repaired by the fibrous tissues; in the scaffold-cell group, osteochondral defect repair was complete, with the emergence of tidal line, and the newborn cartilage was completely integrated with the surrounding normal tissue in addition to a similar thickness. At 12 weeks after surgery, collagen II basically did not express in the control group, weakly expressed in the scaffold group and highly expressed in the scaffold-cell group. In short, the PHBHOx/collagen composite osteochondral scaffold promotes the repair of articular osteochondral defects in the weight-bearing area.