Cartilage Tissue Engineering

This chapter provides an introduction to tissue engineering for cartilage repair. Tissue engineering scaffolds are designed to provide a 3D environment to support and direct cellular processes in their migration, proliferation, and differentiation toward functional tissue. The selection of bioscaffolds for cartilage engineering requires excellent mechanical properties to support cellular functions, biocompatibility, capability of waste and nutrient transport, and sufficient structural integrity for joint reconstruction. Both natural and synthetic materials are applied as cartilage tissue engineering scaffolds in a variety of forms, including fibrous structures, porous sponges, woven or nonwoven meshes, and hydrogels. Biological factors are commonly applied to guide cellular differentiation, migration, adhesion, and gene expression. These factors include soluble biochemical signals, transfection of gene vectors, and cell-cell interactions. Soluble signaling molecules are used to instruct cells to proliferate, differentiate, and generate cartilage matrix during cartilage tissue reconstruction. The signaling molecules of growth factors are investigated intensively, especially TGFβ superfamily, several bone morphogenetic protein (BMPs), insulin-like growth factor (IGF)-1, fibroblast growth factors (FGFs), and epidermal growth factor (EGF). Gene therapy techniques are developed to deliver therapeutic genes encoding necessary gene products to cells at the site of cartilage injury to synthesize biological factors of interest for sustained local expression. Bioreactors are developed to provide adequate mass transfer and mechanical stimulation in order to enhance the biochemical and mechanical properties of engineered cartilage tissues.