Preparation of osteogenic matrices from cultured cells

Bone is a composite material consisting primarily of cells, extracellular matrices, accessory proteins and the complex calcium phosphate salt hydroxyapatite. Collectively, the extracellular network of proteins and accessory molecules that provide the organic component of bone tissue is referred to as the osteogenic extracellular matrix (OECM). OECM provides tensile strength and increases the durability of bone, but the OECM also serves as an attachment site and regulatory substrate for cells and a repository for growth factors and cytokines. Increasingly, purified OECM generated by osteogenic cells in culture has attracted interest because it has the capacity to improve the growth and viability of attached cells, enhances the osteogenic program in vitro and in vivo, and shows great promise as a therapeutic tool for orthopedic tissue engineering. This chapter will describe fundamental protocols for the selection and culture of osteogenic cells and conditions for their osteogenic differentiation, and the synthesis, purification and characterization of OECM. Some examples of immobilization to surfaces for the purpose of two- and three-dimensional culture will also be described.