Stem Cell Engineering for Regeneration of Bone Tissue

Due to their great potential, mesenchymal stem cells (MSC) arc of special interest for regenerative therapies. One of the most investigated areas in this field is the regeneration of bone tissue using tissue engineering strategies. This chapter focuses on osteogenic differentiation and cultivation of human MSC in vitro and their utilisation for tissue engineering of bone tissue, discussing a number of protocols to induce and influence the osteogenic differentiation of MSC into the osteoblastic lineage in vitro. According to the tissue engineering approach, 3D porous biomaterials (scaffolds) are seeded with autologous cells, followed by a period of in vitro cultivation which can he carried out under differentiation-inducing conditions and finally by implantation of the cell-matrix constructs into the defect. Here we describe as an example the in vitro cultivation and osteogenic differentiation of human MSC in porous scaffolds consisting of biomimetically mineralised collagen. This artificial extracellular bone matrix that resemble the nanocomposite made of fibrillar collagen type I and hydroxyapatite crystals in natural hone tissue was furthermore used to establish an in vitro model of the hone remodelling process: osteoblasts derived from human MSC and osteoclast-like cells which were also differentiated from their natural precursors were co-cultured on membranes of mineralised collagen to learn more about the cellular cross talk between both cell types. The concept of in situ tissue engineering, a novel strategy to accelerate bone defect healing, aims at the utilization of natural chemotactic mechanisms to colonise scaffolds with MSC in vivo. Exemplarily, the chemoattraction of human MSC into porous 3D scaffolds of mineralised collagen using the stromal-derived factor In (SDF-1 alpha) is demonstrated.