In Vitro Differentiation of Mouse ES Cells: Bone and Cartilage

The in vitro differentiation of ES cells, which closely recapitulates embryonic cell differentiation processes, has been used as a model system to analyze cell differentiation. This is an alternative way to investigate the consequences of loss of function mutations after gene targeting if knock-out mice cannot be generated. Because of their broad differentiation capacity ES cells are also discussed as an experimental approach to generate cells for transplantation. A common method to differentiate ES cells in vitro is their cultivation as cell aggregates, so-called “embryoid bodies (EBs).” The efficiency of ES cell-derived chondrocyte differentiation is found to be influenced by several parameters, such as the batch of fetal calf serum used for cultivation or the size of EBs. For a reproducible pattern of chondrogenic and osteogenic differentiation it is an important prerequisite to generate EBs of the same size. This is achieved by differentiation of ES cells via hanging drop-cultivation. This chapter describes some basic techniques of ES cell cultivation, the methods used for chondrogenic and osteogenic differentiation of ES cells, for characterization of the specific cell types and for isolation of chondrocytes from EBs. Furthermore, the chapter briefly summarizes approaches to enhance the differentiation efficiency.