Tissue engineering and cell therapy of cartilage and bone

Trauma and disease of bones and joints, frequently involving structural damage to both the articular cartilage surface and the subchondral bone, result in severe pain and disability for millions of people worldwide and represent major challenges for the orthopedic surgeons. Therapeutic repair of skeletal tissues by tissue engineering has raised the interest of the scientific community, providing very promising results in preclinical animal models and clinical pilot studies. In this review, we discuss this approach. The choice of a proper cell type is addressed. The use of terminally differentiated cells, as in the case of autologous chondrocyte implantation, is compared with the advantages/disadvantages of using more undifferentiated cell types, such as stem cells or early mesenchymal progenitors that retain multi-lineage and self-renewal potentials. The need for proper scaffold matrices is also examined, and we provide a brief overview of their fundamental properties. A description of the natural and biosynthetic materials currently used for reconstruction purposes, either of cartilage or bone, is given. Finally, we highlight the positive aspects and the remaining problems that will drive future research in articular cartilage and bone repair.