Articular Cartilage Engineering With Autologous Chondrocyte Transplantation

Although several attempts to improve the repair of injured articular cartilage have recently been described 1-6, articular cartilage resurfacing remains a formidable challenge. Most current cartilage-repair methods depend on an introduction of chondrogenic cells into the defect area. Which cells are best to use and which donor tissue is best for harvesting the cells have yet to be determined. However, since chondrocytes are responsible for the unique features of articular cartilage, it seems rational to use truly committed chondrocytes to repair an articular cartilage defect. In Gothenburg, Sweden, the experience with biological articular resurfacing dates back to the early 1980s. This research has been focused on the use of autologous articular chondrocytes 7-10 for the repair of focal articular cartilage defects, even though other chondrogenic cells are possible alternatives. The primary goal of the initial in vitro chondrocyte cell culture is to increase the number of cells in order to provide a sufficient number to fill a focal defect of articular cartilage. To accomplish this, chondrocytes are isolated from small slices of cartilage harvested arthroscopically from a minor weight-bearing area of the injured knee. The extracellular matrix is removed by enzymatic digestion, and the cells are then expanded in monolayer culture. Once a sufficient number of cells has been obtained, the chondrocytes are suspended in culture medium and are implanted into the cartilage defect with use of a periosteal patch over the defect as a method of cell containment. The expansion of chondrocytes in vitro results in the selection of a limited number of chondrocyte progenitor clones, and the culture process allows the cells to dedifferentiate and revert to a fetal stage. Implantation of the cells into the defect initiates cell condensation and cartilage formation, which is similar to the mesenchymal condensation that occurs during …