Human articular chondrocytes--plasticity and differentiation potential.

Articular cartilage has no or very low ability of self-repair, and untreated lesions may lead to the development of osteoarthritis. One method which has been proven to result in long-term repair of isolated lesions is autologous chondrocyte transplantation. In this method, culture-expanded chondrocytes isolated from full-thickness biopsies, taken from a non-weight-bearing area at the supromedial edge of the femoral condyle, are transplanted back to the patient under a cover of periosteum. The treatment is able to regenerate hyaline cartilage with long-term durability. Although the repair mechanism behind this treatment has not been fully elucidated, emerging data generated by microarray technologies reveal an interesting regeneration process involving cellular and molecular mechanisms found during fetal development. In hyaline cartilage, the human chondrocyte population is generally considered a homogenous cell population, but recently several investigators have demonstrated that cells isolated from human articular cartilage have stem cell properties and that the superficial layer contains such cells. This paper will discuss these recent data and their implications for future treatment strategies aiming to induce regeneration in articular cartilage surfaces.