Chondrocyte Signaling and Artificial Matrices for Articular Cartilage Engineering

The proper functionality of healthy tissue requires maintenance. Even after tissue has undergone trauma, it attempts to repair itself. However, there are tissues within the body that are unable to completely regenerate when inflicted with severe stress, such as articular cartilage. The field of tissue engineering can alleviate this problem by providing cells, biological molecules and scaffolding materials to facilitate regeneration of healthy tissue. In order to achieve this task, fundamental mechanisms of cartilage tissue function needs to be understood. Cartilage is composed of components, such as cells, proteins and macromolecules, which all play a role in maintaining the well-being of the tissue. There has been considerable evidence that the interaction of chondrocytes with proteins and extracellular matrix play an important role in the homeostasis of cartilage. This is a continuously evolving area of study as biologists are intensely discovering new details of the cellular signaling pathways involved in the communication of chondrocytes. Recent studies have implicated that alterations in the signaling pathways of chondrocytes can lead to osteoarthritis, a degenerative condition of articular cartilage. We propose that the success of tissue engineers involves understanding the intricacy of chondrocytes signaling mechanisms in order to maintain their proper function while in contact with biomaterial scaffolds. To this end, we first discuss the basic biology of articular cartilage. Then we will explore the activation of signaling pathways that occur by chondrocytes due to the interaction with proteins (growth factors and cytokines) and extracellular matrix components (type II collagen, glycosaminoglycans and proteoglycans). Finally, we discuss the effects polymeric biomaterials may have on chondrocyte signaling.