Single cell enzymatic dissociation of human embryonic stem cells: a straightforward, robust, and standardized culture method.

The routine culture and expansion of human embryonic stem (hES) cells has been and is still posing a challenge to researchers wishing to take advantage of the cells' unique potential. In contrast to mouse embryonic stem cells, hES cells usually have to be expanded by tedious mechanical microdissection or by enzymatic dissociation to cell clusters of a very narrow size range.It is essential to use a culture system that allows the robust and reproducible enzymatic dissociation of viable hES cell cultures to single cells to allow the scale-up of hES cell cultures as well as the application of hES cells in various experiments, such as FACS, electroporation, and clonal selection.By the development of enzyme-based protocols, which are less labor intensive and less time consuming, much progress has been made over the recent years with regard to improved culture systems for hES cell. We have developed a culture system that is based on single cell enzymatic dissociation (SCED) in combination with a highly supportive feeder cell layer of human foreskin fibroblasts (hFFs). The culture system allows defined enzymatic propagation while maintaining the hES cell lines in an undifferentiated, pluripotent, and normal state.In this chapter, we will show how hES cells, which have been derived and passaged by traditional mechanical dissection, can be rapidly adjusted to propagation by enzymatic dissociation to single cells. The protocols we describe are widely applicable and should therefore be of general use for the reliable mass cultivation of hES cells for various experiments.