Repair of articular cartilage defects with tissue-engineered osteochondral composites in pigs

To compare the results of repair of knee cartilage defects with tissue-engineered osteochondral composites and tissue-engineered cartilage in pigs. Autologous chondrocytes and osteoblasts were seeded on scaffolds of polylactic-co-glycolic acid (PLGA) and tricalcium phosphate (TCP) to generate tissue-engineered cartilage and tissue-engineered bone, respectively. The tissue-engineered osteochondral composite was formed by a chondrocyte-PLGA construct sutured to an osteoblast-TCP construct with an absorbable suture. Cartilage defects were surgically created at the weightbearing surface of the bilateral femoral medial condyles of 12 mini-pigs. Thus, 24 defects in 12 pigs were randomly assigned to three treatment groups: tissue-engineered osteochondral composite group, tissue-engineered cartilage group, and blank control group. Six months after surgery, the regenerated cartilage was scored macroscopically and histologically. The compressive properties and glycosaminoglycan (GAG) content of the cartilage were also assessed. The gross grading scale indicated that the mean scores of the tissue-engineered osteochondral composite group were significantly higher than those of the tissue-engineered cartilage group. According to the International Cartilage Repair Society (ICRS) Visual Histological Assessment Scale, the scores of the osteochondral composite group were significantly better than those of the tissue-engineered cartilage group and blank control group. Assessment of compressive properties and GAG content showed better repair results in the osteochondral composite group than those of the tissue-engineered cartilage group. Using tissue-engineered osteochondral composites to repair cartilage defects was better than that of tissue-engineered cartilage.