The role of periosteum in cartilage repair.

Periosteum, which can be grown in cell and whole tissue cultures, may meet one or more of the three prerequisites for tissue engineered cartilage repair. Periosteum contains pluripotential mesenchymal stem cells with the potential to form either cartilage or bone. Because it can be transplanted as a whole tissue, it can serve as its own scaffold or a matrix onto which other cells and/or growth factors can be adhered. Finally, it produces bioactive factors that are known to be chondrogenic. The chondrocyte precursor cells reside in the cambium layer. These vary in total density and volume with age and in different donor sites. The advantages of whole tissue periosteal transplants for cartilage repair include the fact that this tissue meets the three primary requirements for tissue engineering: a source of cells, a scaffold for delivering and retaining them, and a source of local growth factors. Many growth factors that regulate chondrocytes and cartilage development are synthesized by periosteum in conditions conducive to chondrogenesis. These include transforming growth factor-beta 1, insulinlike growth factor-1, growth and differentiation factor-5, bone morphogenetic protein-2, integrins, and the receptors for these molecules. By additional study of the molecular events in periosteal chondrogenesis, it may be possible to optimize its capacity for articular cartilage repair.