Amniotic fluid-derived stem cells for bone tissue engineering

Implantation of bone substitute materials and autologous bone grafting have been used for the treatment of extensive bone defects. Recent advances in tissue engineering have led to integration of viable, biological bone grafts composed of osteogenic cells proliferating within three-dimensional (3D) scaffolds. Not only could these novel grafts be used for implantation, but also they could serve in basic and translational studies of bone development, disease, and drug discovery. The ability to isolate human cells, expand them to a large density, and differentiate them into bone-forming cells remains critical to the success of human bone graft engineering. This chapter will focus on the characteristics and limitations of human amniotic stem cells and their application in bone tissue engineering. Stem cells have proved to be an ideal source of cells for bone tissue engineering due to their ability to differentiate into osteogenic lineages. Recently, amniotic fluid-derived stem (AFS) cells that are isolated from amniotic fluid removed by amniocentesis have been identified as a novel stem cell source. The proliferative potential of these cells, along with their anti-immunogenic and non-tumorigenic properties, make them an ideal therapeutic candidate for bone tissue regeneration without ethical issues. In this chapter, the current knowledge of AFS cell isolation, characterization, and osteogenic differentiation, as well as tissue engineering approaches for the use of these cells in bone regeneration, is discussed.