Repair of articular osteochondral defects with composite bone marrow derived mesenchymal stem cells and chitosan/hydroxyapatite bilayered scaffold in rabbits.

Objective To evaluate the results of the treatment of osteochondral defects on the femoral condyles by using autologous bone mesenchymal stem cells (BMSCs) combined with chitosan/ hydroxyapatite (CS/HA) bilayered scaffolds in rabbit knee joints.Methods BMSCs derived from Japanese white rabbits aged 2-3 months weighting 1.7-2.0 kg were cultured in vitro with a density of 2×107/ml and seeded onto CS/HA scaffolds.The BMSCs-CS/HA complex was cultured for 10 h and transplanted into the osteochondral defects on the femoral condyles.Thirty-six knees with osteochondral defects created in the femoral condyles were treated (A) by BMSCs combined with CS/HA scaffold, (B) by simple CS/HA scaffold or (C) left untreated, respectively.Six rabbits were sacrificed at 6 and 12 weeks after operation in each group, and the reparative tissue samples evaluated grossly, histologically according to the gross and histological scale.Results The treatment of CS/HA scaffolds improved defect filling compared with that left untreated, while the regenerated tissue was mainly fibrocartilage and showed little bone formation.When implanted with CS/HA scaffold combined with BMSCs, most of the defects were filled with a well-established layer of cartilage tissue with a little bone formation observed by HE staining and toluidine blue staining.Conclusion The BMSCs combined with CS/HA scaffolds to repair osteochondral defects on the femoral condyles is a promising approach for the treatment of osteochondral defects. Key words: Mesenchymal stem cells;  Chitosan;  Hydroxyapatites;  Tissue engineering