Cartilage repair with chondrocytes: clinical and cellular aspects.

Articular cartilage has a limited potential to repair. Unsatisfactory results with current treatment methods (e.g. osteochondral autografts, drilling or microfracturing) has triggered the development of new cartilage restoration techniques including autologous cell transplantation (mesenchymal stem cells or chondrocytes) with or without supporting scaffolds. Autologous chondrocyte transplantation (ACT) was first used in humans in 1987 and the first pilot was published in 1994. Two years after transplantation, 14 of the 16 patients with femoral condyle transplants had a restored joint function and 11 of 15 femoral transplants demonstrated a hyaline repair tissue. Results from patellar transplants were less encouraging. To date, we have treated over 1000 and other groups over 6000 patients. The technique gives stable long-term results with a high percentage of good to excellent results (84-90%) in patients with different types of single femoral condyle lesions, whereas in patients with other types of lesions in the knee it is less successful (average 74%). A better understanding of the repair mechanism induced by the cultured chondrocytes and the regulatory mechanisms controlling chondrogenic differentiation combined with identification and culture of stem cells with chondrogenic potential will be the key to new cartilage treatments.