Combinatorial Approaches in Tissue Engineering: Progenitor Cells, Scaffolds, and Growth Factors

T issue engineering (TE) has the potential of improving the quality of life for many thousands of people throughout the world. One particular area which presents an exciting challenge in this field is the repair and regeneration of cartilage where traumatic injuries and arthritis result in pain and restriction of movement. In order to achieve this goal of tissue engineering cartilage, there are three necessary components: cells for the generation of tissue, a scaffold to support growth and that degrades as the extracellular matrix is generated and a bioactive factor to stimulate the correct biological signals in vivo for tissue growth and integration with native cartilage. Over the last number of years there has been significant interest in progenitor stem cells for TE applications. Mesenchymal stem cells (MSCs) have been shown to differentiate into a range of tissues including bone, cartilage, muscle, tendon, skin and fat. Furthermore, a number of biocompatible biodegradable materials have been identified as carriers for these cells for transplantation. Once transplanted, however, these cell seeded scaffolds require the necessary signals to survive and assimilate in their host environment. Therefore, a number of bioactive factors including growth factors and cytokines are also required for cartilage repair and regeneration. In this chapter, the combinatorial approach of progenitor cells, biodegradable scaffolds and bioactive factors is discussed in relation to cartilage TE. The challenges for the future including cell sources, osteochondral defects and gene therapy are also examined.