Chondrogenesis of mesenchymal stem cells for cartilage tissue engineering

Despite its remarkable ability to resist mechanical loading, articular cartilage is not capable of mounting a useful reparative reaction in response to damage caused by trauma or disease. As a result numerous surgical and medical approaches have been developed to aid the healing of articular cartilage. Despite the success of surgical techniques such as microfracture, recently attentions have been turned to cell based therapies such as autologous chondrocyte implantation (ACI). ACI has produced encouraging results, however better results may be achievable through an evolution of this surgical approach. Since the first generation of ACI techniques changes have been made in the technique e.g. the introduction of collagen membranes instead of periosteal flaps, and more recently the use of collagen scaffolds for cellular delivery. The procedure has also moved on from being performed as an open operation and can now be performed arthroscopically. Despite these advances the procedure still uses chondrocytes harvested from the joint being repaired. These cells are vulnerable to dedifferentiation during the required in vitro expansion, and as a result may not be capable of producing repair tissue once implanted back into the joint. Mesenchymal stem cells (MSCs) may provide a dedifferentiation resistant alternative to chondrocytes. MSCs would also allow for the use of one arthroscopic operation on the affected joint, as opposed to the two operations that are currently required for ACI.